* [PATCH v4 01/17] arm64: cpufeature: Fix meta-capability cpufeature check
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 23:07 ` Suzuki K Poulose
2020-01-23 10:20 ` [PATCH v4 02/17] arm64: cpufeature: add pointer auth meta-capabilities Amit Daniel Kachhap
` (15 subsequent siblings)
16 siblings, 1 reply; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
Some existing meta cpucaps match needs the presence of individual
cpucaps. Currently the individual cpucaps checks it via an array
based flag and this introduces dependency on the array entry order.
This limitation exists only for system scope cpufeature.
This patch introduces a helper function (system_has_cap) to invoke
the matching handler for system scope. This is similar to the
existing helper function (this_cpu_has_cap) for local cpu scope.
Use this new helper function for an existing meta cpucaps.
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
* New patch.
* This is added as suggested by Catalin [1] to avoid the array entry order
dependency.
* A new helper system_has_cap is added.
[1]: http://lists.infradead.org/pipermail/linux-arm-kernel/2020-January/705845.html
arch/arm64/include/asm/cpufeature.h | 1 +
arch/arm64/kernel/cpufeature.c | 13 ++++++++++++-
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 4261d55..695e538 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -382,6 +382,7 @@ extern DECLARE_BITMAP(boot_capabilities, ARM64_NPATCHABLE);
for_each_set_bit(cap, cpu_hwcaps, ARM64_NCAPS)
bool this_cpu_has_cap(unsigned int cap);
+bool system_has_cap(unsigned int cap);
void cpu_set_feature(unsigned int num);
bool cpu_have_feature(unsigned int num);
unsigned long cpu_get_elf_hwcap(void);
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 04cf64e..74d6c13 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -2008,6 +2008,17 @@ bool this_cpu_has_cap(unsigned int n)
return false;
}
+bool system_has_cap(unsigned int n)
+{
+ if (n < ARM64_NCAPS) {
+ const struct arm64_cpu_capabilities *cap = cpu_hwcaps_ptrs[n];
+
+ if (cap)
+ return cap->matches(cap, SCOPE_SYSTEM);
+ }
+ return false;
+}
+
void cpu_set_feature(unsigned int num)
{
WARN_ON(num >= MAX_CPU_FEATURES);
@@ -2081,7 +2092,7 @@ void __init setup_cpu_features(void)
static bool __maybe_unused
cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int __unused)
{
- return (cpus_have_const_cap(ARM64_HAS_PAN) && !cpus_have_const_cap(ARM64_HAS_UAO));
+ return (system_has_cap(ARM64_HAS_PAN) && !system_has_cap(ARM64_HAS_UAO));
}
static void __maybe_unused cpu_enable_cnp(struct arm64_cpu_capabilities const *cap)
--
2.7.4
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^ permalink raw reply related [flat|nested] 24+ messages in thread* Re: [PATCH v4 01/17] arm64: cpufeature: Fix meta-capability cpufeature check
2020-01-23 10:20 ` [PATCH v4 01/17] arm64: cpufeature: Fix meta-capability cpufeature check Amit Daniel Kachhap
@ 2020-01-23 23:07 ` Suzuki K Poulose
2020-01-24 11:58 ` Amit Kachhap
0 siblings, 1 reply; 24+ messages in thread
From: Suzuki K Poulose @ 2020-01-23 23:07 UTC (permalink / raw)
To: amit.kachhap, linux-arm-kernel
Cc: mark.rutland, keescook, catalin.marinas, kristina.martsenko,
dave.martin, broonie, james.morse, ramana.radhakrishnan,
Vincenzo.Frascino, will, ardb
Hi Amit
On 01/23/2020 10:20 AM, Amit Daniel Kachhap wrote:
> Some existing meta cpucaps match needs the presence of individual
> cpucaps. Currently the individual cpucaps checks it via an array
> based flag and this introduces dependency on the array entry order.
> This limitation exists only for system scope cpufeature.
>
> This patch introduces a helper function (system_has_cap) to invoke
> the matching handler for system scope. This is similar to the
> existing helper function (this_cpu_has_cap) for local cpu scope.
It is similar (in name, see more on that below) but this must be limited
to very narrow "window" where :
- We have the system wide safe registers set with all the SMP CPUs
*and*
- The SYSTEM_FEATURE cpu_hwcaps may not have been set.
The normal users must continue to use the existing
cpus_have_{const_}cap() helper(s).
>
> Use this new helper function for an existing meta cpucaps.
>
> Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
> ---
> Changes since v3:
> * New patch.
> * This is added as suggested by Catalin [1] to avoid the array entry order
> dependency.
> * A new helper system_has_cap is added.
>
> [1]: http://lists.infradead.org/pipermail/linux-arm-kernel/2020-January/705845.html
>
> arch/arm64/include/asm/cpufeature.h | 1 +
> arch/arm64/kernel/cpufeature.c | 13 ++++++++++++-
> 2 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> index 4261d55..695e538 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -382,6 +382,7 @@ extern DECLARE_BITMAP(boot_capabilities, ARM64_NPATCHABLE);
> for_each_set_bit(cap, cpu_hwcaps, ARM64_NCAPS)
>
> bool this_cpu_has_cap(unsigned int cap);
> +bool system_has_cap(unsigned int cap);
You don't need this.
> void cpu_set_feature(unsigned int num);
> bool cpu_have_feature(unsigned int num);
> unsigned long cpu_get_elf_hwcap(void);
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 04cf64e..74d6c13 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -2008,6 +2008,17 @@ bool this_cpu_has_cap(unsigned int n)
> return false;
> }
>
> +bool system_has_cap(unsigned int n)
> +{
nit: This could be made static for now.
More importantly, the name is very much similar to "cap" specific
wrappers, e.g, system_has_fpsimd() etc, which could create a confusion
and make people use this instead of the "cpus_have_cap() or
cpus_have_const_cap()". It would be a good idea to make this explicitly
look like an internal helper.
e.g:
__system_matches_cap() to avoid abusing this helper.
Otherwise looks good to me.
Suzuki
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^ permalink raw reply [flat|nested] 24+ messages in thread* Re: [PATCH v4 01/17] arm64: cpufeature: Fix meta-capability cpufeature check
2020-01-23 23:07 ` Suzuki K Poulose
@ 2020-01-24 11:58 ` Amit Kachhap
0 siblings, 0 replies; 24+ messages in thread
From: Amit Kachhap @ 2020-01-24 11:58 UTC (permalink / raw)
To: Suzuki K Poulose, linux-arm-kernel
Cc: mark.rutland, keescook, catalin.marinas, kristina.martsenko,
dave.martin, broonie, james.morse, ramana.radhakrishnan,
Vincenzo.Frascino, will, ardb
Hi Suzuki,
On 1/23/20 11:07 PM, Suzuki K Poulose wrote:
> Hi Amit
>
> On 01/23/2020 10:20 AM, Amit Daniel Kachhap wrote:
>> Some existing meta cpucaps match needs the presence of individual
>> cpucaps. Currently the individual cpucaps checks it via an array
>> based flag and this introduces dependency on the array entry order.
>> This limitation exists only for system scope cpufeature.
>>
>> This patch introduces a helper function (system_has_cap) to invoke
>> the matching handler for system scope. This is similar to the
>> existing helper function (this_cpu_has_cap) for local cpu scope.
>
> It is similar (in name, see more on that below) but this must be limited
> to very narrow "window" where :
> - We have the system wide safe registers set with all the SMP CPUs
> *and*
> - The SYSTEM_FEATURE cpu_hwcaps may not have been set.
>
> The normal users must continue to use the existing
> cpus_have_{const_}cap() helper(s).
>
Thanks for the details. I will update my commit message.
>>
>> Use this new helper function for an existing meta cpucaps.
>>
>> Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
>> ---
>> Changes since v3:
>> * New patch.
>> * This is added as suggested by Catalin [1] to avoid the array entry
>> order
>> dependency.
>> * A new helper system_has_cap is added.
>>
>> [1]:
>> http://lists.infradead.org/pipermail/linux-arm-kernel/2020-January/705845.html
>>
>>
>> arch/arm64/include/asm/cpufeature.h | 1 +
>> arch/arm64/kernel/cpufeature.c | 13 ++++++++++++-
>> 2 files changed, 13 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/include/asm/cpufeature.h
>> b/arch/arm64/include/asm/cpufeature.h
>> index 4261d55..695e538 100644
>> --- a/arch/arm64/include/asm/cpufeature.h
>> +++ b/arch/arm64/include/asm/cpufeature.h
>> @@ -382,6 +382,7 @@ extern DECLARE_BITMAP(boot_capabilities,
>> ARM64_NPATCHABLE);
>> for_each_set_bit(cap, cpu_hwcaps, ARM64_NCAPS)
>> bool this_cpu_has_cap(unsigned int cap);
>> +bool system_has_cap(unsigned int cap);
>
> You don't need this.
ok agreed.
>
>> void cpu_set_feature(unsigned int num);
>> bool cpu_have_feature(unsigned int num);
>> unsigned long cpu_get_elf_hwcap(void);
>> diff --git a/arch/arm64/kernel/cpufeature.c
>> b/arch/arm64/kernel/cpufeature.c
>> index 04cf64e..74d6c13 100644
>> --- a/arch/arm64/kernel/cpufeature.c
>> +++ b/arch/arm64/kernel/cpufeature.c
>> @@ -2008,6 +2008,17 @@ bool this_cpu_has_cap(unsigned int n)
>> return false;
>> }
>> +bool system_has_cap(unsigned int n)
>> +{
>
> nit: This could be made static for now.
>
> More importantly, the name is very much similar to "cap" specific
> wrappers, e.g, system_has_fpsimd() etc, which could create a confusion
> and make people use this instead of the "cpus_have_cap() or
> cpus_have_const_cap()". It would be a good idea to make this explicitly
> look like an internal helper.
> e.g:
>
> __system_matches_cap() to avoid abusing this helper.
Sure. I will change the name.
>
>
> Otherwise looks good to me.
Thanks,
Amit
>
> Suzuki
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^ permalink raw reply [flat|nested] 24+ messages in thread
* [PATCH v4 02/17] arm64: cpufeature: add pointer auth meta-capabilities
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 01/17] arm64: cpufeature: Fix meta-capability cpufeature check Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 03/17] arm64: rename ptrauth key structures to be user-specific Amit Daniel Kachhap
` (14 subsequent siblings)
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
From: Kristina Martsenko <kristina.martsenko@arm.com>
To enable pointer auth for the kernel, we're going to need to check for
the presence of address auth and generic auth using alternative_if. We
currently have two cpucaps for each, but alternative_if needs to check a
single cpucap. So define meta-capabilities that are present when either
of the current two capabilities is present.
Leave the existing four cpucaps in place, as they are still needed to
check for mismatched systems where one CPU has the architected algorithm
but another has the IMP DEF algorithm.
Note, the meta-capabilities were present before but were removed in
commit a56005d32105 ("arm64: cpufeature: Reduce number of pointer auth
CPU caps from 6 to 4") and commit 1e013d06120c ("arm64: cpufeature: Rework
ptr auth hwcaps using multi_entry_cap_matches"), as they were not needed
then. Note, unlike before, the current patch checks the cpucap values
directly, instead of reading the CPU ID register value.
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: commit message and macro rebase, use system_has_cap]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
* uses the new helper system_has_cap added earlier.
arch/arm64/include/asm/cpucaps.h | 4 +++-
arch/arm64/include/asm/cpufeature.h | 6 ++----
arch/arm64/kernel/cpufeature.c | 25 ++++++++++++++++++++++++-
3 files changed, 29 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index b926838..6674ad1 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -56,7 +56,9 @@
#define ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM 46
#define ARM64_WORKAROUND_1542419 47
#define ARM64_WORKAROUND_1319367 48
+#define ARM64_HAS_ADDRESS_AUTH 49
+#define ARM64_HAS_GENERIC_AUTH 50
-#define ARM64_NCAPS 49
+#define ARM64_NCAPS 51
#endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 695e538..8579427 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -591,15 +591,13 @@ static inline bool system_supports_cnp(void)
static inline bool system_supports_address_auth(void)
{
return IS_ENABLED(CONFIG_ARM64_PTR_AUTH) &&
- (cpus_have_const_cap(ARM64_HAS_ADDRESS_AUTH_ARCH) ||
- cpus_have_const_cap(ARM64_HAS_ADDRESS_AUTH_IMP_DEF));
+ cpus_have_const_cap(ARM64_HAS_ADDRESS_AUTH);
}
static inline bool system_supports_generic_auth(void)
{
return IS_ENABLED(CONFIG_ARM64_PTR_AUTH) &&
- (cpus_have_const_cap(ARM64_HAS_GENERIC_AUTH_ARCH) ||
- cpus_have_const_cap(ARM64_HAS_GENERIC_AUTH_IMP_DEF));
+ cpus_have_const_cap(ARM64_HAS_GENERIC_AUTH);
}
static inline bool system_uses_irq_prio_masking(void)
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 74d6c13..378329d6 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1249,6 +1249,20 @@ static void cpu_enable_address_auth(struct arm64_cpu_capabilities const *cap)
sysreg_clear_set(sctlr_el1, 0, SCTLR_ELx_ENIA | SCTLR_ELx_ENIB |
SCTLR_ELx_ENDA | SCTLR_ELx_ENDB);
}
+
+static bool has_address_auth(const struct arm64_cpu_capabilities *entry,
+ int __unused)
+{
+ return system_has_cap(ARM64_HAS_ADDRESS_AUTH_ARCH) ||
+ system_has_cap(ARM64_HAS_ADDRESS_AUTH_IMP_DEF);
+}
+
+static bool has_generic_auth(const struct arm64_cpu_capabilities *entry,
+ int __unused)
+{
+ return system_has_cap(ARM64_HAS_GENERIC_AUTH_ARCH) ||
+ system_has_cap(ARM64_HAS_GENERIC_AUTH_IMP_DEF);
+}
#endif /* CONFIG_ARM64_PTR_AUTH */
#ifdef CONFIG_ARM64_PSEUDO_NMI
@@ -1518,7 +1532,6 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.field_pos = ID_AA64ISAR1_APA_SHIFT,
.min_field_value = ID_AA64ISAR1_APA_ARCHITECTED,
.matches = has_cpuid_feature,
- .cpu_enable = cpu_enable_address_auth,
},
{
.desc = "Address authentication (IMP DEF algorithm)",
@@ -1529,6 +1542,11 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.field_pos = ID_AA64ISAR1_API_SHIFT,
.min_field_value = ID_AA64ISAR1_API_IMP_DEF,
.matches = has_cpuid_feature,
+ },
+ {
+ .capability = ARM64_HAS_ADDRESS_AUTH,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .matches = has_address_auth,
.cpu_enable = cpu_enable_address_auth,
},
{
@@ -1551,6 +1569,11 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.min_field_value = ID_AA64ISAR1_GPI_IMP_DEF,
.matches = has_cpuid_feature,
},
+ {
+ .capability = ARM64_HAS_GENERIC_AUTH,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .matches = has_generic_auth,
+ },
#endif /* CONFIG_ARM64_PTR_AUTH */
#ifdef CONFIG_ARM64_PSEUDO_NMI
{
--
2.7.4
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^ permalink raw reply related [flat|nested] 24+ messages in thread* [PATCH v4 03/17] arm64: rename ptrauth key structures to be user-specific
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 01/17] arm64: cpufeature: Fix meta-capability cpufeature check Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 02/17] arm64: cpufeature: add pointer auth meta-capabilities Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 04/17] arm64: install user ptrauth keys at kernel exit time Amit Daniel Kachhap
` (13 subsequent siblings)
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
From: Kristina Martsenko <kristina.martsenko@arm.com>
We currently enable ptrauth for userspace, but do not use it within the
kernel. We're going to enable it for the kernel, and will need to manage
a separate set of ptrauth keys for the kernel.
We currently keep all 5 keys in struct ptrauth_keys. However, as the
kernel will only need to use 1 key, it is a bit wasteful to allocate a
whole ptrauth_keys struct for every thread.
Therefore, a subsequent patch will define a separate struct, with only 1
key, for the kernel. In preparation for that, rename the existing struct
(and associated macros and functions) to reflect that they are specific
to userspace.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: Re-positioned the patch to reduce the diff]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
*) Added Catalin's Acked-by.
arch/arm64/include/asm/pointer_auth.h | 12 ++++++------
arch/arm64/include/asm/processor.h | 2 +-
arch/arm64/kernel/pointer_auth.c | 8 ++++----
arch/arm64/kernel/ptrace.c | 16 ++++++++--------
4 files changed, 19 insertions(+), 19 deletions(-)
diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h
index 7a24bad..799b079 100644
--- a/arch/arm64/include/asm/pointer_auth.h
+++ b/arch/arm64/include/asm/pointer_auth.h
@@ -22,7 +22,7 @@ struct ptrauth_key {
* We give each process its own keys, which are shared by all threads. The keys
* are inherited upon fork(), and reinitialised upon exec*().
*/
-struct ptrauth_keys {
+struct ptrauth_keys_user {
struct ptrauth_key apia;
struct ptrauth_key apib;
struct ptrauth_key apda;
@@ -30,7 +30,7 @@ struct ptrauth_keys {
struct ptrauth_key apga;
};
-static inline void ptrauth_keys_init(struct ptrauth_keys *keys)
+static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
{
if (system_supports_address_auth()) {
get_random_bytes(&keys->apia, sizeof(keys->apia));
@@ -50,7 +50,7 @@ do { \
write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \
} while (0)
-static inline void ptrauth_keys_switch(struct ptrauth_keys *keys)
+static inline void ptrauth_keys_switch_user(struct ptrauth_keys_user *keys)
{
if (system_supports_address_auth()) {
__ptrauth_key_install(APIA, keys->apia);
@@ -80,12 +80,12 @@ static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
#define ptrauth_thread_init_user(tsk) \
do { \
struct task_struct *__ptiu_tsk = (tsk); \
- ptrauth_keys_init(&__ptiu_tsk->thread.keys_user); \
- ptrauth_keys_switch(&__ptiu_tsk->thread.keys_user); \
+ ptrauth_keys_init_user(&__ptiu_tsk->thread.keys_user); \
+ ptrauth_keys_switch_user(&__ptiu_tsk->thread.keys_user); \
} while (0)
#define ptrauth_thread_switch(tsk) \
- ptrauth_keys_switch(&(tsk)->thread.keys_user)
+ ptrauth_keys_switch_user(&(tsk)->thread.keys_user)
#else /* CONFIG_ARM64_PTR_AUTH */
#define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL)
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 5ba6320..496a928 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -146,7 +146,7 @@ struct thread_struct {
unsigned long fault_code; /* ESR_EL1 value */
struct debug_info debug; /* debugging */
#ifdef CONFIG_ARM64_PTR_AUTH
- struct ptrauth_keys keys_user;
+ struct ptrauth_keys_user keys_user;
#endif
};
diff --git a/arch/arm64/kernel/pointer_auth.c b/arch/arm64/kernel/pointer_auth.c
index c507b58..af5a638 100644
--- a/arch/arm64/kernel/pointer_auth.c
+++ b/arch/arm64/kernel/pointer_auth.c
@@ -9,7 +9,7 @@
int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg)
{
- struct ptrauth_keys *keys = &tsk->thread.keys_user;
+ struct ptrauth_keys_user *keys = &tsk->thread.keys_user;
unsigned long addr_key_mask = PR_PAC_APIAKEY | PR_PAC_APIBKEY |
PR_PAC_APDAKEY | PR_PAC_APDBKEY;
unsigned long key_mask = addr_key_mask | PR_PAC_APGAKEY;
@@ -18,8 +18,8 @@ int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg)
return -EINVAL;
if (!arg) {
- ptrauth_keys_init(keys);
- ptrauth_keys_switch(keys);
+ ptrauth_keys_init_user(keys);
+ ptrauth_keys_switch_user(keys);
return 0;
}
@@ -41,7 +41,7 @@ int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg)
if (arg & PR_PAC_APGAKEY)
get_random_bytes(&keys->apga, sizeof(keys->apga));
- ptrauth_keys_switch(keys);
+ ptrauth_keys_switch_user(keys);
return 0;
}
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 6771c39..ddaff0f 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -986,7 +986,7 @@ static struct ptrauth_key pac_key_from_user(__uint128_t ukey)
}
static void pac_address_keys_to_user(struct user_pac_address_keys *ukeys,
- const struct ptrauth_keys *keys)
+ const struct ptrauth_keys_user *keys)
{
ukeys->apiakey = pac_key_to_user(&keys->apia);
ukeys->apibkey = pac_key_to_user(&keys->apib);
@@ -994,7 +994,7 @@ static void pac_address_keys_to_user(struct user_pac_address_keys *ukeys,
ukeys->apdbkey = pac_key_to_user(&keys->apdb);
}
-static void pac_address_keys_from_user(struct ptrauth_keys *keys,
+static void pac_address_keys_from_user(struct ptrauth_keys_user *keys,
const struct user_pac_address_keys *ukeys)
{
keys->apia = pac_key_from_user(ukeys->apiakey);
@@ -1008,7 +1008,7 @@ static int pac_address_keys_get(struct task_struct *target,
unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf)
{
- struct ptrauth_keys *keys = &target->thread.keys_user;
+ struct ptrauth_keys_user *keys = &target->thread.keys_user;
struct user_pac_address_keys user_keys;
if (!system_supports_address_auth())
@@ -1025,7 +1025,7 @@ static int pac_address_keys_set(struct task_struct *target,
unsigned int pos, unsigned int count,
const void *kbuf, const void __user *ubuf)
{
- struct ptrauth_keys *keys = &target->thread.keys_user;
+ struct ptrauth_keys_user *keys = &target->thread.keys_user;
struct user_pac_address_keys user_keys;
int ret;
@@ -1043,12 +1043,12 @@ static int pac_address_keys_set(struct task_struct *target,
}
static void pac_generic_keys_to_user(struct user_pac_generic_keys *ukeys,
- const struct ptrauth_keys *keys)
+ const struct ptrauth_keys_user *keys)
{
ukeys->apgakey = pac_key_to_user(&keys->apga);
}
-static void pac_generic_keys_from_user(struct ptrauth_keys *keys,
+static void pac_generic_keys_from_user(struct ptrauth_keys_user *keys,
const struct user_pac_generic_keys *ukeys)
{
keys->apga = pac_key_from_user(ukeys->apgakey);
@@ -1059,7 +1059,7 @@ static int pac_generic_keys_get(struct task_struct *target,
unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf)
{
- struct ptrauth_keys *keys = &target->thread.keys_user;
+ struct ptrauth_keys_user *keys = &target->thread.keys_user;
struct user_pac_generic_keys user_keys;
if (!system_supports_generic_auth())
@@ -1076,7 +1076,7 @@ static int pac_generic_keys_set(struct task_struct *target,
unsigned int pos, unsigned int count,
const void *kbuf, const void __user *ubuf)
{
- struct ptrauth_keys *keys = &target->thread.keys_user;
+ struct ptrauth_keys_user *keys = &target->thread.keys_user;
struct user_pac_generic_keys user_keys;
int ret;
--
2.7.4
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^ permalink raw reply related [flat|nested] 24+ messages in thread* [PATCH v4 04/17] arm64: install user ptrauth keys at kernel exit time
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
` (2 preceding siblings ...)
2020-01-23 10:20 ` [PATCH v4 03/17] arm64: rename ptrauth key structures to be user-specific Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 05/17] arm64: create macro to park cpu in an infinite loop Amit Daniel Kachhap
` (12 subsequent siblings)
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
From: Kristina Martsenko <kristina.martsenko@arm.com>
As we're going to enable pointer auth within the kernel and use a
different APIAKey for the kernel itself, so move the user APIAKey
switch to EL0 exception return.
The other 4 keys could remain switched during task switch, but are also
moved to keep things consistent.
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: commit msg, re-positioned the patch, comments]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
* Added a comment to clarify that thread.keys_user.ap* as offset
exceeds the range of ldp instruction.
arch/arm64/include/asm/asm_pointer_auth.h | 49 +++++++++++++++++++++++++++++++
arch/arm64/include/asm/pointer_auth.h | 23 +--------------
arch/arm64/kernel/asm-offsets.c | 11 +++++++
arch/arm64/kernel/entry.S | 3 ++
arch/arm64/kernel/pointer_auth.c | 3 --
arch/arm64/kernel/process.c | 1 -
6 files changed, 64 insertions(+), 26 deletions(-)
create mode 100644 arch/arm64/include/asm/asm_pointer_auth.h
diff --git a/arch/arm64/include/asm/asm_pointer_auth.h b/arch/arm64/include/asm/asm_pointer_auth.h
new file mode 100644
index 0000000..f820a13
--- /dev/null
+++ b/arch/arm64/include/asm/asm_pointer_auth.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_ASM_POINTER_AUTH_H
+#define __ASM_ASM_POINTER_AUTH_H
+
+#include <asm/alternative.h>
+#include <asm/asm-offsets.h>
+#include <asm/cpufeature.h>
+#include <asm/sysreg.h>
+
+#ifdef CONFIG_ARM64_PTR_AUTH
+/*
+ * thread.keys_user.ap* as offset exceeds the #imm offset range
+ * so use the base value of ldp as thread.keys_user and offset as
+ * keys_user.ap*.
+ */
+ .macro ptrauth_keys_install_user tsk, tmp1, tmp2, tmp3
+ mov \tmp1, #THREAD_KEYS_USER
+ add \tmp1, \tsk, \tmp1
+alternative_if_not ARM64_HAS_ADDRESS_AUTH
+ b .Laddr_auth_skip_\@
+alternative_else_nop_endif
+ ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_USER_KEY_APIA]
+ msr_s SYS_APIAKEYLO_EL1, \tmp2
+ msr_s SYS_APIAKEYHI_EL1, \tmp3
+ ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_USER_KEY_APIB]
+ msr_s SYS_APIBKEYLO_EL1, \tmp2
+ msr_s SYS_APIBKEYHI_EL1, \tmp3
+ ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_USER_KEY_APDA]
+ msr_s SYS_APDAKEYLO_EL1, \tmp2
+ msr_s SYS_APDAKEYHI_EL1, \tmp3
+ ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_USER_KEY_APDB]
+ msr_s SYS_APDBKEYLO_EL1, \tmp2
+ msr_s SYS_APDBKEYHI_EL1, \tmp3
+.Laddr_auth_skip_\@:
+alternative_if ARM64_HAS_GENERIC_AUTH
+ ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_USER_KEY_APGA]
+ msr_s SYS_APGAKEYLO_EL1, \tmp2
+ msr_s SYS_APGAKEYHI_EL1, \tmp3
+alternative_else_nop_endif
+ .endm
+
+#else /* CONFIG_ARM64_PTR_AUTH */
+
+ .macro ptrauth_keys_install_user tsk, tmp1, tmp2, tmp3
+ .endm
+
+#endif /* CONFIG_ARM64_PTR_AUTH */
+
+#endif /* __ASM_ASM_POINTER_AUTH_H */
diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h
index 799b079..dabe026 100644
--- a/arch/arm64/include/asm/pointer_auth.h
+++ b/arch/arm64/include/asm/pointer_auth.h
@@ -50,19 +50,6 @@ do { \
write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \
} while (0)
-static inline void ptrauth_keys_switch_user(struct ptrauth_keys_user *keys)
-{
- if (system_supports_address_auth()) {
- __ptrauth_key_install(APIA, keys->apia);
- __ptrauth_key_install(APIB, keys->apib);
- __ptrauth_key_install(APDA, keys->apda);
- __ptrauth_key_install(APDB, keys->apdb);
- }
-
- if (system_supports_generic_auth())
- __ptrauth_key_install(APGA, keys->apga);
-}
-
extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
/*
@@ -78,20 +65,12 @@ static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
}
#define ptrauth_thread_init_user(tsk) \
-do { \
- struct task_struct *__ptiu_tsk = (tsk); \
- ptrauth_keys_init_user(&__ptiu_tsk->thread.keys_user); \
- ptrauth_keys_switch_user(&__ptiu_tsk->thread.keys_user); \
-} while (0)
-
-#define ptrauth_thread_switch(tsk) \
- ptrauth_keys_switch_user(&(tsk)->thread.keys_user)
+ ptrauth_keys_init_user(&(tsk)->thread.keys_user)
#else /* CONFIG_ARM64_PTR_AUTH */
#define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL)
#define ptrauth_strip_insn_pac(lr) (lr)
#define ptrauth_thread_init_user(tsk)
-#define ptrauth_thread_switch(tsk)
#endif /* CONFIG_ARM64_PTR_AUTH */
#endif /* __ASM_POINTER_AUTH_H */
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index a5bdce8..7b1ea2a 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -40,6 +40,9 @@ int main(void)
#endif
BLANK();
DEFINE(THREAD_CPU_CONTEXT, offsetof(struct task_struct, thread.cpu_context));
+#ifdef CONFIG_ARM64_PTR_AUTH
+ DEFINE(THREAD_KEYS_USER, offsetof(struct task_struct, thread.keys_user));
+#endif
BLANK();
DEFINE(S_X0, offsetof(struct pt_regs, regs[0]));
DEFINE(S_X2, offsetof(struct pt_regs, regs[2]));
@@ -128,5 +131,13 @@ int main(void)
DEFINE(SDEI_EVENT_INTREGS, offsetof(struct sdei_registered_event, interrupted_regs));
DEFINE(SDEI_EVENT_PRIORITY, offsetof(struct sdei_registered_event, priority));
#endif
+#ifdef CONFIG_ARM64_PTR_AUTH
+ DEFINE(PTRAUTH_USER_KEY_APIA, offsetof(struct ptrauth_keys_user, apia));
+ DEFINE(PTRAUTH_USER_KEY_APIB, offsetof(struct ptrauth_keys_user, apib));
+ DEFINE(PTRAUTH_USER_KEY_APDA, offsetof(struct ptrauth_keys_user, apda));
+ DEFINE(PTRAUTH_USER_KEY_APDB, offsetof(struct ptrauth_keys_user, apdb));
+ DEFINE(PTRAUTH_USER_KEY_APGA, offsetof(struct ptrauth_keys_user, apga));
+ BLANK();
+#endif
return 0;
}
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 7c6a0a4..18067bb 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -14,6 +14,7 @@
#include <asm/alternative.h>
#include <asm/assembler.h>
#include <asm/asm-offsets.h>
+#include <asm/asm_pointer_auth.h>
#include <asm/cpufeature.h>
#include <asm/errno.h>
#include <asm/esr.h>
@@ -344,6 +345,8 @@ alternative_else_nop_endif
msr cntkctl_el1, x1
4:
#endif
+ ptrauth_keys_install_user tsk, x0, x1, x2
+
apply_ssbd 0, x0, x1
.endif
diff --git a/arch/arm64/kernel/pointer_auth.c b/arch/arm64/kernel/pointer_auth.c
index af5a638..1e77736 100644
--- a/arch/arm64/kernel/pointer_auth.c
+++ b/arch/arm64/kernel/pointer_auth.c
@@ -19,7 +19,6 @@ int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg)
if (!arg) {
ptrauth_keys_init_user(keys);
- ptrauth_keys_switch_user(keys);
return 0;
}
@@ -41,7 +40,5 @@ int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg)
if (arg & PR_PAC_APGAKEY)
get_random_bytes(&keys->apga, sizeof(keys->apga));
- ptrauth_keys_switch_user(keys);
-
return 0;
}
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index d54586d..a7e60a3 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -505,7 +505,6 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,
contextidr_thread_switch(next);
entry_task_switch(next);
uao_thread_switch(next);
- ptrauth_thread_switch(next);
ssbs_thread_switch(next);
/*
--
2.7.4
_______________________________________________
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 24+ messages in thread* [PATCH v4 05/17] arm64: create macro to park cpu in an infinite loop
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
` (3 preceding siblings ...)
2020-01-23 10:20 ` [PATCH v4 04/17] arm64: install user ptrauth keys at kernel exit time Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 06/17] arm64: ptrauth: Add bootup/runtime flags for __cpu_setup Amit Daniel Kachhap
` (11 subsequent siblings)
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
A macro early_park_cpu is added to park the faulted cpu in an infinite
loop. Currently, this macro is substituted in two instances and may be
reused in future.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
* Added Catalins Acked-by.
* After dropping the code to park the ptrauth mismatched cpu in assembly,
this change is not used by ptrauth. But it is retained here as a code
cleanup.
arch/arm64/kernel/head.S | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 989b194..3d18163 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -761,6 +761,17 @@ ENDPROC(__secondary_too_slow)
.endm
/*
+ * Macro to park the cpu in an infinite loop.
+ */
+ .macro early_park_cpu status
+ update_early_cpu_boot_status \status | CPU_STUCK_IN_KERNEL, x1, x2
+.Lepc_\@:
+ wfe
+ wfi
+ b .Lepc_\@
+ .endm
+
+/*
* Enable the MMU.
*
* x0 = SCTLR_EL1 value for turning on the MMU.
@@ -808,24 +819,14 @@ ENTRY(__cpu_secondary_check52bitva)
and x0, x0, #(0xf << ID_AA64MMFR2_LVA_SHIFT)
cbnz x0, 2f
- update_early_cpu_boot_status \
- CPU_STUCK_IN_KERNEL | CPU_STUCK_REASON_52_BIT_VA, x0, x1
-1: wfe
- wfi
- b 1b
-
+ early_park_cpu CPU_STUCK_REASON_52_BIT_VA
#endif
2: ret
ENDPROC(__cpu_secondary_check52bitva)
__no_granule_support:
/* Indicate that this CPU can't boot and is stuck in the kernel */
- update_early_cpu_boot_status \
- CPU_STUCK_IN_KERNEL | CPU_STUCK_REASON_NO_GRAN, x1, x2
-1:
- wfe
- wfi
- b 1b
+ early_park_cpu CPU_STUCK_REASON_NO_GRAN
ENDPROC(__no_granule_support)
#ifdef CONFIG_RELOCATABLE
--
2.7.4
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^ permalink raw reply related [flat|nested] 24+ messages in thread* [PATCH v4 06/17] arm64: ptrauth: Add bootup/runtime flags for __cpu_setup
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
` (4 preceding siblings ...)
2020-01-23 10:20 ` [PATCH v4 05/17] arm64: create macro to park cpu in an infinite loop Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 07/17] arm64: cpufeature: handle conflicts based on capability Amit Daniel Kachhap
` (10 subsequent siblings)
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
This patch allows __cpu_setup to be invoked with one of these flags,
ARM64_CPU_BOOT_PRIMARY, ARM64_CPU_BOOT_SECONDARY or ARM64_CPU_RUNTIME.
This is required as some cpufeatures need different handling during
different scenarios.
The input parameter in x0 is preserved till the end to be used inside
this function.
There should be no functional change with this patch and is useful
for the subsequent ptrauth patch which utilizes it. Some upcoming
arm cpufeatures can also utilize these flags.
Suggested-by: James Morse <james.morse@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
* Renamed macro ARM64_CPU_BOOT_LATE to ARM64_CPU_BOOT_SECONDARY
* Added James Suggested-by and Suzuki Reviewed-by tags.
arch/arm64/include/asm/smp.h | 5 +++++
arch/arm64/kernel/head.S | 2 ++
arch/arm64/kernel/sleep.S | 2 ++
arch/arm64/mm/proc.S | 26 +++++++++++++++-----------
4 files changed, 24 insertions(+), 11 deletions(-)
diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index a0c8a0b..8159000 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -23,6 +23,11 @@
#define CPU_STUCK_REASON_52_BIT_VA (UL(1) << CPU_STUCK_REASON_SHIFT)
#define CPU_STUCK_REASON_NO_GRAN (UL(2) << CPU_STUCK_REASON_SHIFT)
+/* Options for __cpu_setup */
+#define ARM64_CPU_BOOT_PRIMARY (1)
+#define ARM64_CPU_BOOT_SECONDARY (2)
+#define ARM64_CPU_RUNTIME (3)
+
#ifndef __ASSEMBLY__
#include <asm/percpu.h>
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 3d18163..5a7ce15 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -118,6 +118,7 @@ ENTRY(stext)
* On return, the CPU will be ready for the MMU to be turned on and
* the TCR will have been set.
*/
+ mov x0, #ARM64_CPU_BOOT_PRIMARY
bl __cpu_setup // initialise processor
b __primary_switch
ENDPROC(stext)
@@ -712,6 +713,7 @@ secondary_startup:
* Common entry point for secondary CPUs.
*/
bl __cpu_secondary_check52bitva
+ mov x0, #ARM64_CPU_BOOT_SECONDARY
bl __cpu_setup // initialise processor
adrp x1, swapper_pg_dir
bl __enable_mmu
diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
index f5b04dd..7b2f2e6 100644
--- a/arch/arm64/kernel/sleep.S
+++ b/arch/arm64/kernel/sleep.S
@@ -3,6 +3,7 @@
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/assembler.h>
+#include <asm/smp.h>
.text
/*
@@ -99,6 +100,7 @@ ENDPROC(__cpu_suspend_enter)
.pushsection ".idmap.text", "awx"
ENTRY(cpu_resume)
bl el2_setup // if in EL2 drop to EL1 cleanly
+ mov x0, #ARM64_CPU_RUNTIME
bl __cpu_setup
/* enable the MMU early - so we can access sleep_save_stash by va */
adrp x1, swapper_pg_dir
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index a1e0592..081b946 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -400,21 +400,25 @@ ENDPROC(idmap_kpti_install_ng_mappings)
/*
* __cpu_setup
*
- * Initialise the processor for turning the MMU on. Return in x0 the
- * value of the SCTLR_EL1 register.
+ * Initialise the processor for turning the MMU on.
+ *
+ * Input:
+ * x0 with a flag ARM64_CPU_BOOT_PRIMARY/ARM64_CPU_BOOT_SECONDARY/ARM64_CPU_RUNTIME.
+ * Output:
+ * Return in x0 the value of the SCTLR_EL1 register.
*/
.pushsection ".idmap.text", "awx"
ENTRY(__cpu_setup)
tlbi vmalle1 // Invalidate local TLB
dsb nsh
- mov x0, #3 << 20
- msr cpacr_el1, x0 // Enable FP/ASIMD
- mov x0, #1 << 12 // Reset mdscr_el1 and disable
- msr mdscr_el1, x0 // access to the DCC from EL0
+ mov x1, #3 << 20
+ msr cpacr_el1, x1 // Enable FP/ASIMD
+ mov x1, #1 << 12 // Reset mdscr_el1 and disable
+ msr mdscr_el1, x1 // access to the DCC from EL0
isb // Unmask debug exceptions now,
enable_dbg // since this is per-cpu
- reset_pmuserenr_el0 x0 // Disable PMU access from EL0
+ reset_pmuserenr_el0 x1 // Disable PMU access from EL0
/*
* Memory region attributes for LPAE:
*
@@ -435,10 +439,6 @@ ENTRY(__cpu_setup)
MAIR(0xbb, MT_NORMAL_WT)
msr mair_el1, x5
/*
- * Prepare SCTLR
- */
- mov_q x0, SCTLR_EL1_SET
- /*
* Set/prepare TCR and TTBR. We use 512GB (39-bit) address range for
* both user and kernel.
*/
@@ -474,5 +474,9 @@ ENTRY(__cpu_setup)
1:
#endif /* CONFIG_ARM64_HW_AFDBM */
msr tcr_el1, x10
+ /*
+ * Prepare SCTLR
+ */
+ mov_q x0, SCTLR_EL1_SET
ret // return to head.S
ENDPROC(__cpu_setup)
--
2.7.4
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^ permalink raw reply related [flat|nested] 24+ messages in thread* [PATCH v4 07/17] arm64: cpufeature: handle conflicts based on capability
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
` (5 preceding siblings ...)
2020-01-23 10:20 ` [PATCH v4 06/17] arm64: ptrauth: Add bootup/runtime flags for __cpu_setup Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 08/17] arm64: enable ptrauth earlier Amit Daniel Kachhap
` (9 subsequent siblings)
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
From: Kristina Martsenko <kristina.martsenko@arm.com>
Each system capability can be of either boot, local, or system scope,
depending on when the state of the capability is finalized. When we
detect a conflict on a late CPU, we either offline the CPU or panic the
system. We currently always panic if the conflict is caused by a boot
scope capability, and offline the CPU if the conflict is caused by a
local or system scope capability.
We're going to want to add a new capability (for pointer authentication)
which needs to be boot scope but doesn't need to panic the system when a
conflict is detected. So add a new flag to specify whether the
capability requires the system to panic or not. Current boot scope
capabilities are updated to set the flag, so there should be no
functional change as a result of this patch.
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
* This patch was present in v1 version but was dropped due to
enabling ptrauth in the assembly. However as discussed with Catalin [1]
it is better to park cpu with mismatched ptrauth from the cpufeature
framework itself.
* Retained the earlier Reviewed-by tags.
[1]: http://lists.infradead.org/pipermail/linux-arm-kernel/2020-January/706628.html
arch/arm64/include/asm/cpufeature.h | 18 ++++++++++++++++--
arch/arm64/kernel/cpufeature.c | 23 +++++++++--------------
2 files changed, 25 insertions(+), 16 deletions(-)
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 8579427..bb33c93 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -208,6 +208,10 @@ extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0;
* In some non-typical cases either both (a) and (b), or neither,
* should be permitted. This can be described by including neither
* or both flags in the capability's type field.
+ *
+ * In case of a conflict, the CPU is prevented from booting. If the
+ * ARM64_CPUCAP_PANIC_ON_CONFLICT flag is specified for the capability,
+ * then a kernel panic is triggered.
*/
@@ -240,6 +244,8 @@ extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0;
#define ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU ((u16)BIT(4))
/* Is it safe for a late CPU to miss this capability when system has it */
#define ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU ((u16)BIT(5))
+/* Panic when a conflict is detected */
+#define ARM64_CPUCAP_PANIC_ON_CONFLICT ((u16)BIT(6))
/*
* CPU errata workarounds that need to be enabled at boot time if one or
@@ -279,9 +285,11 @@ extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0;
/*
* CPU feature used early in the boot based on the boot CPU. All secondary
- * CPUs must match the state of the capability as detected by the boot CPU.
+ * CPUs must match the state of the capability as detected by the boot CPU. In
+ * case of a conflict, a kernel panic is triggered.
*/
-#define ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE ARM64_CPUCAP_SCOPE_BOOT_CPU
+#define ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE \
+ (ARM64_CPUCAP_SCOPE_BOOT_CPU | ARM64_CPUCAP_PANIC_ON_CONFLICT)
struct arm64_cpu_capabilities {
const char *desc;
@@ -352,6 +360,12 @@ cpucap_late_cpu_permitted(const struct arm64_cpu_capabilities *cap)
return !!(cap->type & ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU);
}
+static inline bool
+cpucap_panic_on_conflict(const struct arm64_cpu_capabilities *cap)
+{
+ return !!(cap->type & ARM64_CPUCAP_PANIC_ON_CONFLICT);
+}
+
/*
* Generic helper for handling capabilties with multiple (match,enable) pairs
* of call backs, sharing the same capability bit.
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 378329d6..664b77e 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1857,10 +1857,8 @@ static void __init enable_cpu_capabilities(u16 scope_mask)
* Run through the list of capabilities to check for conflicts.
* If the system has already detected a capability, take necessary
* action on this CPU.
- *
- * Returns "false" on conflicts.
*/
-static bool verify_local_cpu_caps(u16 scope_mask)
+static void verify_local_cpu_caps(u16 scope_mask)
{
int i;
bool cpu_has_cap, system_has_cap;
@@ -1905,10 +1903,12 @@ static bool verify_local_cpu_caps(u16 scope_mask)
pr_crit("CPU%d: Detected conflict for capability %d (%s), System: %d, CPU: %d\n",
smp_processor_id(), caps->capability,
caps->desc, system_has_cap, cpu_has_cap);
- return false;
- }
- return true;
+ if (cpucap_panic_on_conflict(caps))
+ cpu_panic_kernel();
+ else
+ cpu_die_early();
+ }
}
/*
@@ -1918,12 +1918,8 @@ static bool verify_local_cpu_caps(u16 scope_mask)
static void check_early_cpu_features(void)
{
verify_cpu_asid_bits();
- /*
- * Early features are used by the kernel already. If there
- * is a conflict, we cannot proceed further.
- */
- if (!verify_local_cpu_caps(SCOPE_BOOT_CPU))
- cpu_panic_kernel();
+
+ verify_local_cpu_caps(SCOPE_BOOT_CPU);
}
static void
@@ -1971,8 +1967,7 @@ static void verify_local_cpu_capabilities(void)
* check_early_cpu_features(), as they need to be verified
* on all secondary CPUs.
*/
- if (!verify_local_cpu_caps(SCOPE_ALL & ~SCOPE_BOOT_CPU))
- cpu_die_early();
+ verify_local_cpu_caps(SCOPE_ALL & ~SCOPE_BOOT_CPU);
verify_local_elf_hwcaps(arm64_elf_hwcaps);
--
2.7.4
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^ permalink raw reply related [flat|nested] 24+ messages in thread* [PATCH v4 08/17] arm64: enable ptrauth earlier
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
` (6 preceding siblings ...)
2020-01-23 10:20 ` [PATCH v4 07/17] arm64: cpufeature: handle conflicts based on capability Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 09/17] arm64: initialize and switch ptrauth kernel keys Amit Daniel Kachhap
` (8 subsequent siblings)
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
From: Kristina Martsenko <kristina.martsenko@arm.com>
When the kernel is compiled with pointer auth instructions, the boot CPU
needs to start using address auth very early, so change the cpucap to
account for this.
Pointer auth must be enabled before we call C functions, because it is
not possible to enter a function with pointer auth disabled and exit it
with pointer auth enabled. Note, mismatches between architected and
IMPDEF algorithms will still be caught by the cpufeature framework (the
separate *_ARCH and *_IMP_DEF cpucaps).
Note the change in behavior: if the boot CPU has address auth and a
late CPU does not, then the late CPU is parked by the cpufeature
framework. Also, if the boot CPU does not have address auth and the late
CPU has then the late cpu will still boot but with ptrauth feature
disabled.
Leave generic authentication as a "system scope" cpucap for now, since
initially the kernel will only use address authentication.
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: Re-worked ptrauth setup logic, comments]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
* Changed the parking position of secondary cpu's with missing ptrauth features from
assembly to cpufeature framework. This was pointed by Catalin [1].
[1]: http://lists.infradead.org/pipermail/linux-arm-kernel/2020-January/706628.html
arch/arm64/Kconfig | 6 ++++++
arch/arm64/include/asm/cpufeature.h | 9 +++++++++
arch/arm64/include/asm/smp.h | 1 +
arch/arm64/kernel/cpufeature.c | 13 +++----------
arch/arm64/kernel/head.S | 1 +
arch/arm64/kernel/smp.c | 2 ++
arch/arm64/mm/proc.S | 31 +++++++++++++++++++++++++++++++
7 files changed, 53 insertions(+), 10 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index e688dfa..86cb782 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1483,6 +1483,12 @@ config ARM64_PTR_AUTH
be enabled. However, KVM guest also require VHE mode and hence
CONFIG_ARM64_VHE=y option to use this feature.
+ If the feature is present on the boot CPU but not on a late CPU, then
+ the late CPU will be parked. Also, if the boot CPU does not have
+ address auth and the late CPU has then the late CPU will still boot
+ but with the feature disabled. On such a system, this option should
+ not be selected.
+
endmenu
config ARM64_SVE
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index bb33c93..ad06dd5 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -291,6 +291,15 @@ extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0;
#define ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE \
(ARM64_CPUCAP_SCOPE_BOOT_CPU | ARM64_CPUCAP_PANIC_ON_CONFLICT)
+/*
+ * CPU feature used early in the boot based on the boot CPU. It is safe for a
+ * late CPU to have this feature even though the boot CPU hasn't enabled it,
+ * although the feature will not be used by Linux in this case. If the boot CPU
+ * has enabled this feature already, then every late CPU must have it.
+ */
+#define ARM64_CPUCAP_BOOT_CPU_FEATURE \
+ (ARM64_CPUCAP_SCOPE_BOOT_CPU | ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU)
+
struct arm64_cpu_capabilities {
const char *desc;
u16 capability;
diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index 8159000..5334d69 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -22,6 +22,7 @@
#define CPU_STUCK_REASON_52_BIT_VA (UL(1) << CPU_STUCK_REASON_SHIFT)
#define CPU_STUCK_REASON_NO_GRAN (UL(2) << CPU_STUCK_REASON_SHIFT)
+#define CPU_STUCK_REASON_NO_PTRAUTH (UL(4) << CPU_STUCK_REASON_SHIFT)
/* Options for __cpu_setup */
#define ARM64_CPU_BOOT_PRIMARY (1)
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 664b77e..9582acc 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1244,12 +1244,6 @@ static void cpu_clear_disr(const struct arm64_cpu_capabilities *__unused)
#endif /* CONFIG_ARM64_RAS_EXTN */
#ifdef CONFIG_ARM64_PTR_AUTH
-static void cpu_enable_address_auth(struct arm64_cpu_capabilities const *cap)
-{
- sysreg_clear_set(sctlr_el1, 0, SCTLR_ELx_ENIA | SCTLR_ELx_ENIB |
- SCTLR_ELx_ENDA | SCTLR_ELx_ENDB);
-}
-
static bool has_address_auth(const struct arm64_cpu_capabilities *entry,
int __unused)
{
@@ -1526,7 +1520,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
{
.desc = "Address authentication (architected algorithm)",
.capability = ARM64_HAS_ADDRESS_AUTH_ARCH,
- .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .type = ARM64_CPUCAP_BOOT_CPU_FEATURE,
.sys_reg = SYS_ID_AA64ISAR1_EL1,
.sign = FTR_UNSIGNED,
.field_pos = ID_AA64ISAR1_APA_SHIFT,
@@ -1536,7 +1530,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
{
.desc = "Address authentication (IMP DEF algorithm)",
.capability = ARM64_HAS_ADDRESS_AUTH_IMP_DEF,
- .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .type = ARM64_CPUCAP_BOOT_CPU_FEATURE,
.sys_reg = SYS_ID_AA64ISAR1_EL1,
.sign = FTR_UNSIGNED,
.field_pos = ID_AA64ISAR1_API_SHIFT,
@@ -1545,9 +1539,8 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
},
{
.capability = ARM64_HAS_ADDRESS_AUTH,
- .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .type = ARM64_CPUCAP_BOOT_CPU_FEATURE,
.matches = has_address_auth,
- .cpu_enable = cpu_enable_address_auth,
},
{
.desc = "Generic authentication (architected algorithm)",
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 5a7ce15..cc21a10 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -13,6 +13,7 @@
#include <linux/init.h>
#include <linux/irqchip/arm-gic-v3.h>
+#include <asm/alternative.h>
#include <asm/assembler.h>
#include <asm/boot.h>
#include <asm/ptrace.h>
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index d4ed9a1..f2761a9 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -164,6 +164,8 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
pr_crit("CPU%u: does not support 52-bit VAs\n", cpu);
if (status & CPU_STUCK_REASON_NO_GRAN)
pr_crit("CPU%u: does not support %luK granule \n", cpu, PAGE_SIZE / SZ_1K);
+ if (status & CPU_STUCK_REASON_NO_PTRAUTH)
+ pr_crit("CPU%u: does not support pointer authentication\n", cpu);
cpus_stuck_in_kernel++;
break;
case CPU_PANIC_KERNEL:
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 081b946..fe2b126 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -16,6 +16,7 @@
#include <asm/pgtable-hwdef.h>
#include <asm/cpufeature.h>
#include <asm/alternative.h>
+#include <asm/smp.h>
#ifdef CONFIG_ARM64_64K_PAGES
#define TCR_TG_FLAGS TCR_TG0_64K | TCR_TG1_64K
@@ -474,9 +475,39 @@ ENTRY(__cpu_setup)
1:
#endif /* CONFIG_ARM64_HW_AFDBM */
msr tcr_el1, x10
+ mov x1, x0
/*
* Prepare SCTLR
*/
mov_q x0, SCTLR_EL1_SET
+
+#ifdef CONFIG_ARM64_PTR_AUTH
+ /* No ptrauth setup for run time cpus */
+ cmp x1, #ARM64_CPU_RUNTIME
+ b.eq 3f
+
+ /* Check if the CPU supports ptrauth */
+ mrs x2, id_aa64isar1_el1
+ ubfx x2, x2, #ID_AA64ISAR1_APA_SHIFT, #8
+ cbz x2, 3f
+
+ msr_s SYS_APIAKEYLO_EL1, xzr
+ msr_s SYS_APIAKEYHI_EL1, xzr
+
+ /* Just enable ptrauth for primary cpu */
+ cmp x1, #ARM64_CPU_BOOT_PRIMARY
+ b.eq 2f
+
+ /* if !system_supports_address_auth() then skip enable */
+alternative_if_not ARM64_HAS_ADDRESS_AUTH
+ b 3f
+alternative_else_nop_endif
+
+2: /* Enable ptrauth instructions */
+ ldr x2, =SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | \
+ SCTLR_ELx_ENDA | SCTLR_ELx_ENDB
+ orr x0, x0, x2
+3:
+#endif
ret // return to head.S
ENDPROC(__cpu_setup)
--
2.7.4
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^ permalink raw reply related [flat|nested] 24+ messages in thread* [PATCH v4 09/17] arm64: initialize and switch ptrauth kernel keys
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
` (7 preceding siblings ...)
2020-01-23 10:20 ` [PATCH v4 08/17] arm64: enable ptrauth earlier Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 10/17] arm64: initialize ptrauth keys for kernel booting task Amit Daniel Kachhap
` (7 subsequent siblings)
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
From: Kristina Martsenko <kristina.martsenko@arm.com>
Set up keys to use pointer authentication within the kernel. The kernel
will be compiled with APIAKey instructions, the other keys are currently
unused. Each task is given its own APIAKey, which is initialized during
fork. The key is changed during context switch and on kernel entry from
EL0.
The keys for idle threads need to be set before calling any C functions,
because it is not possible to enter and exit a function with different
keys.
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: Modified secondary cores key structure, comments]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
*) Added Catalin's Reviewed-by.
arch/arm64/include/asm/asm_pointer_auth.h | 14 ++++++++++++++
arch/arm64/include/asm/pointer_auth.h | 13 +++++++++++++
arch/arm64/include/asm/processor.h | 1 +
arch/arm64/include/asm/smp.h | 4 ++++
arch/arm64/kernel/asm-offsets.c | 5 +++++
arch/arm64/kernel/entry.S | 3 +++
arch/arm64/kernel/process.c | 2 ++
arch/arm64/kernel/smp.c | 8 ++++++++
arch/arm64/mm/proc.S | 12 ++++++++++++
9 files changed, 62 insertions(+)
diff --git a/arch/arm64/include/asm/asm_pointer_auth.h b/arch/arm64/include/asm/asm_pointer_auth.h
index f820a13..4152afe 100644
--- a/arch/arm64/include/asm/asm_pointer_auth.h
+++ b/arch/arm64/include/asm/asm_pointer_auth.h
@@ -39,11 +39,25 @@ alternative_if ARM64_HAS_GENERIC_AUTH
alternative_else_nop_endif
.endm
+ .macro ptrauth_keys_install_kernel tsk, tmp1, tmp2, tmp3
+alternative_if ARM64_HAS_ADDRESS_AUTH
+ mov \tmp1, #THREAD_KEYS_KERNEL
+ add \tmp1, \tsk, \tmp1
+ ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_KERNEL_KEY_APIA]
+ msr_s SYS_APIAKEYLO_EL1, \tmp2
+ msr_s SYS_APIAKEYHI_EL1, \tmp3
+ isb
+alternative_else_nop_endif
+ .endm
+
#else /* CONFIG_ARM64_PTR_AUTH */
.macro ptrauth_keys_install_user tsk, tmp1, tmp2, tmp3
.endm
+ .macro ptrauth_keys_install_kernel tsk, tmp1, tmp2, tmp3
+ .endm
+
#endif /* CONFIG_ARM64_PTR_AUTH */
#endif /* __ASM_ASM_POINTER_AUTH_H */
diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h
index dabe026..aa956ca 100644
--- a/arch/arm64/include/asm/pointer_auth.h
+++ b/arch/arm64/include/asm/pointer_auth.h
@@ -30,6 +30,10 @@ struct ptrauth_keys_user {
struct ptrauth_key apga;
};
+struct ptrauth_keys_kernel {
+ struct ptrauth_key apia;
+};
+
static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
{
if (system_supports_address_auth()) {
@@ -50,6 +54,12 @@ do { \
write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \
} while (0)
+static inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
+{
+ if (system_supports_address_auth())
+ get_random_bytes(&keys->apia, sizeof(keys->apia));
+}
+
extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
/*
@@ -66,11 +76,14 @@ static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
#define ptrauth_thread_init_user(tsk) \
ptrauth_keys_init_user(&(tsk)->thread.keys_user)
+#define ptrauth_thread_init_kernel(tsk) \
+ ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
#else /* CONFIG_ARM64_PTR_AUTH */
#define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL)
#define ptrauth_strip_insn_pac(lr) (lr)
#define ptrauth_thread_init_user(tsk)
+#define ptrauth_thread_init_kernel(tsk)
#endif /* CONFIG_ARM64_PTR_AUTH */
#endif /* __ASM_POINTER_AUTH_H */
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 496a928..4c77da5 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -147,6 +147,7 @@ struct thread_struct {
struct debug_info debug; /* debugging */
#ifdef CONFIG_ARM64_PTR_AUTH
struct ptrauth_keys_user keys_user;
+ struct ptrauth_keys_kernel keys_kernel;
#endif
};
diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index 5334d69..4e92150 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -36,6 +36,7 @@
#include <linux/threads.h>
#include <linux/cpumask.h>
#include <linux/thread_info.h>
+#include <asm/pointer_auth.h>
DECLARE_PER_CPU_READ_MOSTLY(int, cpu_number);
@@ -93,6 +94,9 @@ asmlinkage void secondary_start_kernel(void);
struct secondary_data {
void *stack;
struct task_struct *task;
+#ifdef CONFIG_ARM64_PTR_AUTH
+ struct ptrauth_keys_kernel ptrauth_key;
+#endif
long status;
};
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 7b1ea2a..9981a0a 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -42,6 +42,7 @@ int main(void)
DEFINE(THREAD_CPU_CONTEXT, offsetof(struct task_struct, thread.cpu_context));
#ifdef CONFIG_ARM64_PTR_AUTH
DEFINE(THREAD_KEYS_USER, offsetof(struct task_struct, thread.keys_user));
+ DEFINE(THREAD_KEYS_KERNEL, offsetof(struct task_struct, thread.keys_kernel));
#endif
BLANK();
DEFINE(S_X0, offsetof(struct pt_regs, regs[0]));
@@ -91,6 +92,9 @@ int main(void)
BLANK();
DEFINE(CPU_BOOT_STACK, offsetof(struct secondary_data, stack));
DEFINE(CPU_BOOT_TASK, offsetof(struct secondary_data, task));
+#ifdef CONFIG_ARM64_PTR_AUTH
+ DEFINE(CPU_BOOT_PTRAUTH_KEY, offsetof(struct secondary_data, ptrauth_key));
+#endif
BLANK();
#ifdef CONFIG_KVM_ARM_HOST
DEFINE(VCPU_CONTEXT, offsetof(struct kvm_vcpu, arch.ctxt));
@@ -137,6 +141,7 @@ int main(void)
DEFINE(PTRAUTH_USER_KEY_APDA, offsetof(struct ptrauth_keys_user, apda));
DEFINE(PTRAUTH_USER_KEY_APDB, offsetof(struct ptrauth_keys_user, apdb));
DEFINE(PTRAUTH_USER_KEY_APGA, offsetof(struct ptrauth_keys_user, apga));
+ DEFINE(PTRAUTH_KERNEL_KEY_APIA, offsetof(struct ptrauth_keys_kernel, apia));
BLANK();
#endif
return 0;
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 18067bb..5e6ebcc 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -174,6 +174,7 @@ alternative_cb_end
apply_ssbd 1, x22, x23
+ ptrauth_keys_install_kernel tsk, x20, x22, x23
.else
add x21, sp, #S_FRAME_SIZE
get_current_task tsk
@@ -345,6 +346,7 @@ alternative_else_nop_endif
msr cntkctl_el1, x1
4:
#endif
+ /* No kernel C function calls after this as user keys are set. */
ptrauth_keys_install_user tsk, x0, x1, x2
apply_ssbd 0, x0, x1
@@ -898,6 +900,7 @@ ENTRY(cpu_switch_to)
ldr lr, [x8]
mov sp, x9
msr sp_el0, x1
+ ptrauth_keys_install_kernel x1, x8, x9, x10
ret
ENDPROC(cpu_switch_to)
NOKPROBE(cpu_switch_to)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index a7e60a3..58b4736 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -376,6 +376,8 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long stack_start,
*/
fpsimd_flush_task_state(p);
+ ptrauth_thread_init_kernel(p);
+
if (likely(!(p->flags & PF_KTHREAD))) {
*childregs = *current_pt_regs();
childregs->regs[0] = 0;
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index f2761a9..3fa0fbf 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -112,6 +112,10 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
*/
secondary_data.task = idle;
secondary_data.stack = task_stack_page(idle) + THREAD_SIZE;
+#if defined(CONFIG_ARM64_PTR_AUTH)
+ secondary_data.ptrauth_key.apia.lo = idle->thread.keys_kernel.apia.lo;
+ secondary_data.ptrauth_key.apia.hi = idle->thread.keys_kernel.apia.hi;
+#endif
update_cpu_boot_status(CPU_MMU_OFF);
__flush_dcache_area(&secondary_data, sizeof(secondary_data));
@@ -138,6 +142,10 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
secondary_data.task = NULL;
secondary_data.stack = NULL;
+#if defined(CONFIG_ARM64_PTR_AUTH)
+ secondary_data.ptrauth_key.apia.lo = 0;
+ secondary_data.ptrauth_key.apia.hi = 0;
+#endif
__flush_dcache_area(&secondary_data, sizeof(secondary_data));
status = READ_ONCE(secondary_data.status);
if (ret && status) {
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index fe2b126..796734f 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -491,6 +491,10 @@ ENTRY(__cpu_setup)
ubfx x2, x2, #ID_AA64ISAR1_APA_SHIFT, #8
cbz x2, 3f
+ /*
+ * The primary cpu keys are reset here and can be
+ * re-initialised with some proper values later.
+ */
msr_s SYS_APIAKEYLO_EL1, xzr
msr_s SYS_APIAKEYHI_EL1, xzr
@@ -503,6 +507,14 @@ alternative_if_not ARM64_HAS_ADDRESS_AUTH
b 3f
alternative_else_nop_endif
+ /* Install ptrauth key for secondary cpus */
+ adr_l x2, secondary_data
+ ldr x3, [x2, #CPU_BOOT_TASK] // get secondary_data.task
+ cbz x3, 2f // check for slow booting cpus
+ ldp x3, x4, [x2, #CPU_BOOT_PTRAUTH_KEY]
+ msr_s SYS_APIAKEYLO_EL1, x3
+ msr_s SYS_APIAKEYHI_EL1, x4
+
2: /* Enable ptrauth instructions */
ldr x2, =SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | \
SCTLR_ELx_ENDA | SCTLR_ELx_ENDB
--
2.7.4
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^ permalink raw reply related [flat|nested] 24+ messages in thread* [PATCH v4 10/17] arm64: initialize ptrauth keys for kernel booting task
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
` (8 preceding siblings ...)
2020-01-23 10:20 ` [PATCH v4 09/17] arm64: initialize and switch ptrauth kernel keys Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 11/17] arm64: mask PAC bits of __builtin_return_address Amit Daniel Kachhap
` (6 subsequent siblings)
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
This patch uses the existing boot_init_stack_canary arch function
to initialize the ptrauth keys for the booting task in the primary
core. The requirement here is that it should be always inline and
the caller must never return.
As pointer authentication too detects a subset of stack corruption
so it makes sense to place this code here.
Both pointer authentication and stack canary codes are protected
by their respective config option.
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
*) Fixed inline attribute as __always_inline.
*) Added Catalin's Reviewed-by.
arch/arm64/include/asm/pointer_auth.h | 11 ++++++++++-
arch/arm64/include/asm/stackprotector.h | 5 +++++
include/linux/stackprotector.h | 2 +-
3 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h
index aa956ca..833d3f9 100644
--- a/arch/arm64/include/asm/pointer_auth.h
+++ b/arch/arm64/include/asm/pointer_auth.h
@@ -54,12 +54,18 @@ do { \
write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \
} while (0)
-static inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
+static __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
{
if (system_supports_address_auth())
get_random_bytes(&keys->apia, sizeof(keys->apia));
}
+static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kernel *keys)
+{
+ if (system_supports_address_auth())
+ __ptrauth_key_install(APIA, keys->apia);
+}
+
extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
/*
@@ -78,12 +84,15 @@ static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
ptrauth_keys_init_user(&(tsk)->thread.keys_user)
#define ptrauth_thread_init_kernel(tsk) \
ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
+#define ptrauth_thread_switch_kernel(tsk) \
+ ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
#else /* CONFIG_ARM64_PTR_AUTH */
#define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL)
#define ptrauth_strip_insn_pac(lr) (lr)
#define ptrauth_thread_init_user(tsk)
#define ptrauth_thread_init_kernel(tsk)
+#define ptrauth_thread_switch_kernel(tsk)
#endif /* CONFIG_ARM64_PTR_AUTH */
#endif /* __ASM_POINTER_AUTH_H */
diff --git a/arch/arm64/include/asm/stackprotector.h b/arch/arm64/include/asm/stackprotector.h
index 5884a2b..7263e0b 100644
--- a/arch/arm64/include/asm/stackprotector.h
+++ b/arch/arm64/include/asm/stackprotector.h
@@ -15,6 +15,7 @@
#include <linux/random.h>
#include <linux/version.h>
+#include <asm/pointer_auth.h>
extern unsigned long __stack_chk_guard;
@@ -26,6 +27,7 @@ extern unsigned long __stack_chk_guard;
*/
static __always_inline void boot_init_stack_canary(void)
{
+#if defined(CONFIG_STACKPROTECTOR)
unsigned long canary;
/* Try to get a semi random initial value. */
@@ -36,6 +38,9 @@ static __always_inline void boot_init_stack_canary(void)
current->stack_canary = canary;
if (!IS_ENABLED(CONFIG_STACKPROTECTOR_PER_TASK))
__stack_chk_guard = current->stack_canary;
+#endif
+ ptrauth_thread_init_kernel(current);
+ ptrauth_thread_switch_kernel(current);
}
#endif /* _ASM_STACKPROTECTOR_H */
diff --git a/include/linux/stackprotector.h b/include/linux/stackprotector.h
index 6b792d0..4c678c4 100644
--- a/include/linux/stackprotector.h
+++ b/include/linux/stackprotector.h
@@ -6,7 +6,7 @@
#include <linux/sched.h>
#include <linux/random.h>
-#ifdef CONFIG_STACKPROTECTOR
+#if defined(CONFIG_STACKPROTECTOR) || defined(CONFIG_ARM64_PTR_AUTH)
# include <asm/stackprotector.h>
#else
static inline void boot_init_stack_canary(void)
--
2.7.4
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^ permalink raw reply related [flat|nested] 24+ messages in thread* [PATCH v4 11/17] arm64: mask PAC bits of __builtin_return_address
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
` (9 preceding siblings ...)
2020-01-23 10:20 ` [PATCH v4 10/17] arm64: initialize ptrauth keys for kernel booting task Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 12/17] arm64: unwind: strip PAC from kernel addresses Amit Daniel Kachhap
` (5 subsequent siblings)
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
This redefines __builtin_return_address to mask pac bits
when Pointer Authentication is enabled. As __builtin_return_address
is used mostly used to refer to the caller function symbol address
so masking runtime generated pac bits will help to find the match.
This patch adds a new file (asm/compiler.h) and is transitively
included (via include/compiler_types.h) on the compiler command line
so it is guaranteed to be loaded and the users of this macro will
not find a wrong version.
A helper macro ptrauth_kernel_pac_mask is created for this purpose
and added in this file. A similar macro ptrauth_user_pac_mask exists
in pointer_auth.h and is now moved here for the sake of consistency.
This change fixes the utilities like cat /proc/vmallocinfo to show
correct symbol names.
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
* Changed VA_BITS to vabits_actual for kernel pacmask as pointed by Catalin [1].
[1]: http://lists.infradead.org/pipermail/linux-arm-kernel/2020-January/706604.html
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/compiler.h | 20 ++++++++++++++++++++
arch/arm64/include/asm/pointer_auth.h | 13 +++++--------
3 files changed, 26 insertions(+), 8 deletions(-)
create mode 100644 arch/arm64/include/asm/compiler.h
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 86cb782..beded60 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -116,6 +116,7 @@ config ARM64
select HAVE_ALIGNED_STRUCT_PAGE if SLUB
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_BITREVERSE
+ select HAVE_ARCH_COMPILER_H
select HAVE_ARCH_HUGE_VMAP
select HAVE_ARCH_JUMP_LABEL
select HAVE_ARCH_JUMP_LABEL_RELATIVE
diff --git a/arch/arm64/include/asm/compiler.h b/arch/arm64/include/asm/compiler.h
new file mode 100644
index 0000000..085e7cd0
--- /dev/null
+++ b/arch/arm64/include/asm/compiler.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_COMPILER_H
+#define __ASM_COMPILER_H
+
+#if defined(CONFIG_ARM64_PTR_AUTH)
+
+/*
+ * The EL0/EL1 pointer bits used by a pointer authentication code.
+ * This is dependent on TBI0/TBI1 being enabled, or bits 63:56 would also apply.
+ */
+#define ptrauth_user_pac_mask() GENMASK_ULL(54, vabits_actual)
+#define ptrauth_kernel_pac_mask() GENMASK_ULL(63, vabits_actual)
+
+#define __builtin_return_address(val) \
+ (void *)((unsigned long)__builtin_return_address(val) | \
+ ptrauth_kernel_pac_mask())
+
+#endif /* CONFIG_ARM64_PTR_AUTH */
+
+#endif /* __ASM_COMPILER_H */
diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h
index 833d3f9..5340dbb 100644
--- a/arch/arm64/include/asm/pointer_auth.h
+++ b/arch/arm64/include/asm/pointer_auth.h
@@ -68,16 +68,13 @@ static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kerne
extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
-/*
- * The EL0 pointer bits used by a pointer authentication code.
- * This is dependent on TBI0 being enabled, or bits 63:56 would also apply.
- */
-#define ptrauth_user_pac_mask() GENMASK(54, vabits_actual)
-
-/* Only valid for EL0 TTBR0 instruction pointers */
+/* Valid for EL0 TTBR0 and EL1 TTBR1 instruction pointers */
static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
{
- return ptr & ~ptrauth_user_pac_mask();
+ if (ptr & BIT_ULL(55))
+ return ptr | ptrauth_kernel_pac_mask();
+ else
+ return ptr & ~ptrauth_user_pac_mask();
}
#define ptrauth_thread_init_user(tsk) \
--
2.7.4
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^ permalink raw reply related [flat|nested] 24+ messages in thread* [PATCH v4 12/17] arm64: unwind: strip PAC from kernel addresses
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
` (10 preceding siblings ...)
2020-01-23 10:20 ` [PATCH v4 11/17] arm64: mask PAC bits of __builtin_return_address Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 13/17] arm64: __show_regs: strip PAC from lr in printk Amit Daniel Kachhap
` (4 subsequent siblings)
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
From: Mark Rutland <mark.rutland@arm.com>
When we enable pointer authentication in the kernel, LR values saved to
the stack will have a PAC which we must strip in order to retrieve the
real return address.
Strip PACs when unwinding the stack in order to account for this.
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: Re-position ptrauth_strip_insn_pac, comment]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
*) Added Catalin's Acked-by.
arch/arm64/kernel/stacktrace.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index a336cb1..b479df7 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -14,6 +14,7 @@
#include <linux/stacktrace.h>
#include <asm/irq.h>
+#include <asm/pointer_auth.h>
#include <asm/stack_pointer.h>
#include <asm/stacktrace.h>
@@ -101,6 +102,8 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+ frame->pc = ptrauth_strip_insn_pac(frame->pc);
+
/*
* Frames created upon entry from EL0 have NULL FP and PC values, so
* don't bother reporting these. Frames created by __noreturn functions
--
2.7.4
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^ permalink raw reply related [flat|nested] 24+ messages in thread* [PATCH v4 13/17] arm64: __show_regs: strip PAC from lr in printk
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
` (11 preceding siblings ...)
2020-01-23 10:20 ` [PATCH v4 12/17] arm64: unwind: strip PAC from kernel addresses Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 14/17] arm64: suspend: restore the kernel ptrauth keys Amit Daniel Kachhap
` (3 subsequent siblings)
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
lr is printed with %pS which will try to find an entry in kallsyms.
After enabling pointer authentication, this match will fail due to
PAC present in the lr.
Strip PAC from the lr to display the correct symbol name.
Suggested-by: James Morse <james.morse@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
*) Added Catalin's Acked-by.
arch/arm64/kernel/process.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 58b4736..883bc2a0 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -262,7 +262,7 @@ void __show_regs(struct pt_regs *regs)
if (!user_mode(regs)) {
printk("pc : %pS\n", (void *)regs->pc);
- printk("lr : %pS\n", (void *)lr);
+ printk("lr : %pS\n", (void *)ptrauth_strip_insn_pac(lr));
} else {
printk("pc : %016llx\n", regs->pc);
printk("lr : %016llx\n", lr);
--
2.7.4
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^ permalink raw reply related [flat|nested] 24+ messages in thread* [PATCH v4 14/17] arm64: suspend: restore the kernel ptrauth keys
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
` (12 preceding siblings ...)
2020-01-23 10:20 ` [PATCH v4 13/17] arm64: __show_regs: strip PAC from lr in printk Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 15/17] kconfig: Add support for 'as-option' Amit Daniel Kachhap
` (2 subsequent siblings)
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
This patch restores the kernel keys from current task during
cpu resume after the mmu is turned on and ptrauth is enabled.
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
arch/arm64/kernel/sleep.S | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
index 7b2f2e6..f9db925 100644
--- a/arch/arm64/kernel/sleep.S
+++ b/arch/arm64/kernel/sleep.S
@@ -2,6 +2,7 @@
#include <linux/errno.h>
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
+#include <asm/asm_pointer_auth.h>
#include <asm/assembler.h>
#include <asm/smp.h>
@@ -134,6 +135,11 @@ ENTRY(_cpu_resume)
*/
bl cpu_do_resume
+#ifdef CONFIG_ARM64_PTR_AUTH
+ get_current_task x1
+ ptrauth_keys_install_kernel x1, x2, x3, x4
+#endif
+
#ifdef CONFIG_KASAN
mov x0, sp
bl kasan_unpoison_task_stack_below
--
2.7.4
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^ permalink raw reply related [flat|nested] 24+ messages in thread* [PATCH v4 15/17] kconfig: Add support for 'as-option'
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
` (13 preceding siblings ...)
2020-01-23 10:20 ` [PATCH v4 14/17] arm64: suspend: restore the kernel ptrauth keys Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:30 ` Ard Biesheuvel
2020-01-23 10:20 ` [PATCH v4 16/17] arm64: compile the kernel with ptrauth return address signing Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 17/17] lkdtm: arm64: test kernel pointer authentication Amit Daniel Kachhap
16 siblings, 1 reply; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
linux-kbuild, Kristina Martsenko, Dave Martin, Masahiro Yamada,
Mark Brown, James Morse, Ramana Radhakrishnan,
Amit Daniel Kachhap, Vincenzo Frascino, Will Deacon,
Ard Biesheuvel
From: Vincenzo Frascino <vincenzo.frascino@arm.com>
Currently kconfig does not have a feature that allows to detect if the
used assembler supports a specific compilation option.
Introduce 'as-option' to serve this purpose in the context of Kconfig:
config X
def_bool $(as-option,...)
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: linux-kbuild@vger.kernel.org
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
*) Changed the assembler option to -c instead of earlier -E.
*) Added Masahiro Acked-by.
scripts/Kconfig.include | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
index d4adfbe..c4b4424 100644
--- a/scripts/Kconfig.include
+++ b/scripts/Kconfig.include
@@ -31,6 +31,10 @@ cc-option = $(success,$(CC) -Werror $(CLANG_FLAGS) $(1) -E -x c /dev/null -o /de
# Return y if the linker supports <flag>, n otherwise
ld-option = $(success,$(LD) -v $(1))
+# $(as-option,<flag>)
+# Return y if the assembler supports <flag>, n otherwise
+as-option = $(success, $(CC) $(CLANG_FLAGS) $(1) -c -x assembler /dev/null -o /dev/zero)
+
# check if $(CC) and $(LD) exist
$(error-if,$(failure,command -v $(CC)),compiler '$(CC)' not found)
$(error-if,$(failure,command -v $(LD)),linker '$(LD)' not found)
--
2.7.4
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 24+ messages in thread* Re: [PATCH v4 15/17] kconfig: Add support for 'as-option'
2020-01-23 10:20 ` [PATCH v4 15/17] kconfig: Add support for 'as-option' Amit Daniel Kachhap
@ 2020-01-23 10:30 ` Ard Biesheuvel
2020-01-23 10:52 ` Vincenzo Frascino
0 siblings, 1 reply; 24+ messages in thread
From: Ard Biesheuvel @ 2020-01-23 10:30 UTC (permalink / raw)
To: Amit Daniel Kachhap
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Linux Kbuild mailing list, Kristina Martsenko, Dave Martin,
Masahiro Yamada, Mark Brown, James Morse, Ramana Radhakrishnan,
Vincenzo Frascino, Will Deacon, Ard Biesheuvel, linux-arm-kernel
On Thu, 23 Jan 2020 at 11:22, Amit Daniel Kachhap <amit.kachhap@arm.com> wrote:
>
> From: Vincenzo Frascino <vincenzo.frascino@arm.com>
>
> Currently kconfig does not have a feature that allows to detect if the
> used assembler supports a specific compilation option.
>
> Introduce 'as-option' to serve this purpose in the context of Kconfig:
>
> config X
> def_bool $(as-option,...)
>
> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> Cc: linux-kbuild@vger.kernel.org
> Acked-by: Masahiro Yamada <masahiroy@kernel.org>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
> ---
> Changes since v3:
> *) Changed the assembler option to -c instead of earlier -E.
> *) Added Masahiro Acked-by.
>
> scripts/Kconfig.include | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
> index d4adfbe..c4b4424 100644
> --- a/scripts/Kconfig.include
> +++ b/scripts/Kconfig.include
> @@ -31,6 +31,10 @@ cc-option = $(success,$(CC) -Werror $(CLANG_FLAGS) $(1) -E -x c /dev/null -o /de
> # Return y if the linker supports <flag>, n otherwise
> ld-option = $(success,$(LD) -v $(1))
>
> +# $(as-option,<flag>)
> +# Return y if the assembler supports <flag>, n otherwise
> +as-option = $(success, $(CC) $(CLANG_FLAGS) $(1) -c -x assembler /dev/null -o /dev/zero)
Did you mean '-o /dev/null' here?
> +
> # check if $(CC) and $(LD) exist
> $(error-if,$(failure,command -v $(CC)),compiler '$(CC)' not found)
> $(error-if,$(failure,command -v $(LD)),linker '$(LD)' not found)
> --
> 2.7.4
>
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: [PATCH v4 15/17] kconfig: Add support for 'as-option'
2020-01-23 10:30 ` Ard Biesheuvel
@ 2020-01-23 10:52 ` Vincenzo Frascino
2020-01-26 14:45 ` Masahiro Yamada
0 siblings, 1 reply; 24+ messages in thread
From: Vincenzo Frascino @ 2020-01-23 10:52 UTC (permalink / raw)
To: Ard Biesheuvel, Amit Daniel Kachhap
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Linux Kbuild mailing list, Kristina Martsenko, Dave Martin,
Masahiro Yamada, Mark Brown, James Morse, Ramana Radhakrishnan,
Will Deacon, Ard Biesheuvel, linux-arm-kernel
[-- Attachment #1: Type: text/plain, Size: 2041 bytes --]
On 23/01/2020 10:30, Ard Biesheuvel wrote:
> On Thu, 23 Jan 2020 at 11:22, Amit Daniel Kachhap <amit.kachhap@arm.com> wrote:
>>
>> From: Vincenzo Frascino <vincenzo.frascino@arm.com>
>>
>> Currently kconfig does not have a feature that allows to detect if the
>> used assembler supports a specific compilation option.
>>
>> Introduce 'as-option' to serve this purpose in the context of Kconfig:
>>
>> config X
>> def_bool $(as-option,...)
>>
>> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
>> Cc: linux-kbuild@vger.kernel.org
>> Acked-by: Masahiro Yamada <masahiroy@kernel.org>
>> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
>> ---
>> Changes since v3:
>> *) Changed the assembler option to -c instead of earlier -E.
>> *) Added Masahiro Acked-by.
>>
>> scripts/Kconfig.include | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
>> index d4adfbe..c4b4424 100644
>> --- a/scripts/Kconfig.include
>> +++ b/scripts/Kconfig.include
>> @@ -31,6 +31,10 @@ cc-option = $(success,$(CC) -Werror $(CLANG_FLAGS) $(1) -E -x c /dev/null -o /de
>> # Return y if the linker supports <flag>, n otherwise
>> ld-option = $(success,$(LD) -v $(1))
>>
>> +# $(as-option,<flag>)
>> +# Return y if the assembler supports <flag>, n otherwise
>> +as-option = $(success, $(CC) $(CLANG_FLAGS) $(1) -c -x assembler /dev/null -o /dev/zero)
>
> Did you mean '-o /dev/null' here?
>
No /dev/zero because otherwise I get a warning that says that I am trying to
compile an object into the same file.
If I invert /dev/zero and /dev/null this trashes the compilation. It took me a
while to get the right combination.
>> +
>> # check if $(CC) and $(LD) exist
>> $(error-if,$(failure,command -v $(CC)),compiler '$(CC)' not found)
>> $(error-if,$(failure,command -v $(LD)),linker '$(LD)' not found)
>> --
>> 2.7.4
>>
--
Regards,
Vincenzo
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_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: [PATCH v4 15/17] kconfig: Add support for 'as-option'
2020-01-23 10:52 ` Vincenzo Frascino
@ 2020-01-26 14:45 ` Masahiro Yamada
2020-01-27 9:33 ` Vincenzo Frascino
0 siblings, 1 reply; 24+ messages in thread
From: Masahiro Yamada @ 2020-01-26 14:45 UTC (permalink / raw)
To: Vincenzo Frascino
Cc: Mark Rutland, Kees Cook, Ard Biesheuvel,
Linux Kbuild mailing list, Catalin Marinas, Suzuki K Poulose,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Will Deacon,
Ard Biesheuvel, linux-arm-kernel
On Thu, Jan 23, 2020 at 7:52 PM Vincenzo Frascino
<vincenzo.frascino@arm.com> wrote:
>
> On 23/01/2020 10:30, Ard Biesheuvel wrote:
> > On Thu, 23 Jan 2020 at 11:22, Amit Daniel Kachhap <amit.kachhap@arm.com> wrote:
> >>
> >> From: Vincenzo Frascino <vincenzo.frascino@arm.com>
> >>
> >> Currently kconfig does not have a feature that allows to detect if the
> >> used assembler supports a specific compilation option.
> >>
> >> Introduce 'as-option' to serve this purpose in the context of Kconfig:
> >>
> >> config X
> >> def_bool $(as-option,...)
> >>
> >> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> >> Cc: linux-kbuild@vger.kernel.org
> >> Acked-by: Masahiro Yamada <masahiroy@kernel.org>
> >> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> >> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
> >> ---
> >> Changes since v3:
> >> *) Changed the assembler option to -c instead of earlier -E.
> >> *) Added Masahiro Acked-by.
> >>
> >> scripts/Kconfig.include | 4 ++++
> >> 1 file changed, 4 insertions(+)
> >>
> >> diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
> >> index d4adfbe..c4b4424 100644
> >> --- a/scripts/Kconfig.include
> >> +++ b/scripts/Kconfig.include
> >> @@ -31,6 +31,10 @@ cc-option = $(success,$(CC) -Werror $(CLANG_FLAGS) $(1) -E -x c /dev/null -o /de
> >> # Return y if the linker supports <flag>, n otherwise
> >> ld-option = $(success,$(LD) -v $(1))
> >>
> >> +# $(as-option,<flag>)
> >> +# Return y if the assembler supports <flag>, n otherwise
> >> +as-option = $(success, $(CC) $(CLANG_FLAGS) $(1) -c -x assembler /dev/null -o /dev/zero)
> >
> > Did you mean '-o /dev/null' here?
> >
>
> No /dev/zero because otherwise I get a warning that says that I am trying to
> compile an object into the same file.
>
> If I invert /dev/zero and /dev/null this trashes the compilation. It took me a
> while to get the right combination.
What compiler produces such a warning?
GCC? Clang?
--
Best Regards
Masahiro Yamada
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: [PATCH v4 15/17] kconfig: Add support for 'as-option'
2020-01-26 14:45 ` Masahiro Yamada
@ 2020-01-27 9:33 ` Vincenzo Frascino
0 siblings, 0 replies; 24+ messages in thread
From: Vincenzo Frascino @ 2020-01-27 9:33 UTC (permalink / raw)
To: Masahiro Yamada
Cc: Mark Rutland, Kees Cook, Ard Biesheuvel,
Linux Kbuild mailing list, Catalin Marinas, Suzuki K Poulose,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Will Deacon,
Ard Biesheuvel, linux-arm-kernel
[-- Attachment #1: Type: text/plain, Size: 762 bytes --]
Hi Masahiro,
On 26/01/2020 14:45, Masahiro Yamada wrote:
> On Thu, Jan 23, 2020 at 7:52 PM Vincenzo Frascino
> <vincenzo.frascino@arm.com> wrote:
>>
[...]
>>
>> No /dev/zero because otherwise I get a warning that says that I am trying to
>> compile an object into the same file.
>>
>> If I invert /dev/zero and /dev/null this trashes the compilation. It took me a
>> while to get the right combination.
>
>
> What compiler produces such a warning?
> GCC? Clang?
>
It is GCC:
$ aarch64-none-linux-gnu-gcc -c -x assembler /dev/null -o /dev/null
Assembler messages:
Fatal error: The input '/dev/null' and output '/dev/null' files are the same
>
>
>
> --
> Best Regards
> Masahiro Yamada
>
--
Regards,
Vincenzo
[-- Attachment #2: pEpkey.asc --]
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[-- Attachment #3: Type: text/plain, Size: 176 bytes --]
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 24+ messages in thread
* [PATCH v4 16/17] arm64: compile the kernel with ptrauth return address signing
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
` (14 preceding siblings ...)
2020-01-23 10:20 ` [PATCH v4 15/17] kconfig: Add support for 'as-option' Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
2020-01-23 10:20 ` [PATCH v4 17/17] lkdtm: arm64: test kernel pointer authentication Amit Daniel Kachhap
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Masahiro Yamada, Mark Brown,
James Morse, Ramana Radhakrishnan, Amit Daniel Kachhap,
Vincenzo Frascino, Will Deacon, Ard Biesheuvel
From: Kristina Martsenko <kristina.martsenko@arm.com>
Compile all functions with two ptrauth instructions: PACIASP in the
prologue to sign the return address, and AUTIASP in the epilogue to
authenticate the return address (from the stack). If authentication
fails, the return will cause an instruction abort to be taken, followed
by an oops and killing the task.
This should help protect the kernel against attacks using
return-oriented programming. As ptrauth protects the return address, it
can also serve as a replacement for CONFIG_STACKPROTECTOR, although note
that it does not protect other parts of the stack.
The new instructions are in the HINT encoding space, so on a system
without ptrauth they execute as NOPs.
CONFIG_ARM64_PTR_AUTH now not only enables ptrauth for userspace and KVM
guests, but also automatically builds the kernel with ptrauth
instructions if the compiler supports it. If there is no compiler
support, we do not warn that the kernel was built without ptrauth
instructions.
GCC 7 and 8 support the -msign-return-address option, while GCC 9
deprecates that option and replaces it with -mbranch-protection. Support
both options.
Clang uses an external assembler hence this patch makes sure that the
correct parameters (-march=armv8.3-a) are passed down to help it recognize
the ptrauth instructions. This option is not used for GNU toolchain.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Co-developed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: Cover leaf function, comments]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
*) Removed compiler version check and added compiler Kconfig dependencies
as pointed by Catalin [1].
*) Enabling warnings for incompatile compilers/assemblers will be done separately.
[1]: http://lists.infradead.org/pipermail/linux-arm-kernel/2020-January/706623.html
arch/arm64/Kconfig | 20 +++++++++++++++++++-
arch/arm64/Makefile | 11 +++++++++++
2 files changed, 30 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index beded60..da04b78 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1467,6 +1467,7 @@ config ARM64_PTR_AUTH
bool "Enable support for pointer authentication"
default y
depends on !KVM || ARM64_VHE
+ depends on (CC_HAS_SIGN_RETURN_ADDRESS || CC_HAS_BRANCH_PROT_PAC_RET) && AS_HAS_PAC
help
Pointer authentication (part of the ARMv8.3 Extensions) provides
instructions for signing and authenticating pointers against secret
@@ -1474,11 +1475,17 @@ config ARM64_PTR_AUTH
and other attacks.
This option enables these instructions at EL0 (i.e. for userspace).
-
Choosing this option will cause the kernel to initialise secret keys
for each process at exec() time, with these keys being
context-switched along with the process.
+ If the compiler supports the -mbranch-protection or
+ -msign-return-address flag (e.g. GCC 7 or later), then this option
+ will also cause the kernel itself to be compiled with return address
+ protection. In this case, and if the target hardware is known to
+ support pointer authentication, then CONFIG_STACKPROTECTOR can be
+ disabled with minimal loss of protection.
+
The feature is detected at runtime. If the feature is not present in
hardware it will not be advertised to userspace/KVM guest nor will it
be enabled. However, KVM guest also require VHE mode and hence
@@ -1490,6 +1497,17 @@ config ARM64_PTR_AUTH
but with the feature disabled. On such a system, this option should
not be selected.
+config CC_HAS_BRANCH_PROT_PAC_RET
+ # GCC 9 or later, clang 8 or later
+ def_bool $(cc-option,-mbranch-protection=pac-ret+leaf)
+
+config CC_HAS_SIGN_RETURN_ADDRESS
+ # GCC 7, 8
+ def_bool $(cc-option,-msign-return-address=all)
+
+config AS_HAS_PAC
+ def_bool $(as-option,-Wa$(comma)-march=armv8.3-a)
+
endmenu
config ARM64_SVE
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 1fbe24d..6a1da59 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -72,6 +72,17 @@ stack_protector_prepare: prepare0
include/generated/asm-offsets.h))
endif
+ifeq ($(CONFIG_ARM64_PTR_AUTH),y)
+branch-prot-flags-$(CONFIG_CC_HAS_SIGN_RETURN_ADDRESS) := -msign-return-address=all
+branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET) := -mbranch-protection=pac-ret+leaf
+# -march=armv8.3-a enables the non-nops instructions for PAC, to avoid the compiler
+# to generate them and consequently to break the single image contract we pass it
+# only to the assembler when clang is selected as a compiler. For the GNU toolchain
+# this option is not used.
+branch-prot-flags-$(CONFIG_AS_HAS_PAC) += -Wa,-march=armv8.3-a
+KBUILD_CFLAGS += $(branch-prot-flags-y)
+endif
+
ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
KBUILD_CPPFLAGS += -mbig-endian
CHECKFLAGS += -D__AARCH64EB__
--
2.7.4
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^ permalink raw reply related [flat|nested] 24+ messages in thread* [PATCH v4 17/17] lkdtm: arm64: test kernel pointer authentication
2020-01-23 10:20 [PATCH v4 00/17] arm64: return address signing Amit Daniel Kachhap
` (15 preceding siblings ...)
2020-01-23 10:20 ` [PATCH v4 16/17] arm64: compile the kernel with ptrauth return address signing Amit Daniel Kachhap
@ 2020-01-23 10:20 ` Amit Daniel Kachhap
16 siblings, 0 replies; 24+ messages in thread
From: Amit Daniel Kachhap @ 2020-01-23 10:20 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Mark Rutland, Kees Cook, Suzuki K Poulose, Catalin Marinas,
Kristina Martsenko, Dave Martin, Mark Brown, James Morse,
Ramana Radhakrishnan, Amit Daniel Kachhap, Vincenzo Frascino,
Will Deacon, Ard Biesheuvel
This test is specific for arm64. When in-kernel Pointer Authentication
config is enabled, the return address stored in the stack is signed.
This feature helps in ROP kind of attack. If any parameters used to
generate the pac (<key, sp, lr>) is modified then this will fail in
the authentication stage and will lead to abort.
This test changes the input parameter APIA kernel keys to cause abort.
The pac computed from the new key can be same as last due to hash
collision so this is retried for few times as there is no reliable way
to compare the pacs. Even though this test may fail even after retries
but this may cause authentication failure at a later stage in earlier
function returns.
This test can be invoked as,
echo CORRUPT_PAC > /sys/kernel/debug/provoke-crash/DIRECT
or as below if inserted as a module,
insmod lkdtm.ko cpoint_name=DIRECT cpoint_type=CORRUPT_PAC cpoint_count=1
[ 13.118166] lkdtm: Performing direct entry CORRUPT_PAC
[ 13.118298] lkdtm: Clearing PAC from the return address
[ 13.118466] Unable to handle kernel paging request at virtual address bfff8000108648ec
[ 13.118626] Mem abort info:
[ 13.118666] ESR = 0x86000004
[ 13.118866] EC = 0x21: IABT (current EL), IL = 32 bits
[ 13.118966] SET = 0, FnV = 0
[ 13.119117] EA = 0, S1PTW = 0
Cc: Kees Cook <keescook@chromium.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
*) Added Catalin's Acked-by.
drivers/misc/lkdtm/bugs.c | 36 ++++++++++++++++++++++++++++++++++++
drivers/misc/lkdtm/core.c | 1 +
drivers/misc/lkdtm/lkdtm.h | 1 +
3 files changed, 38 insertions(+)
diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
index de87693..cc92bc3 100644
--- a/drivers/misc/lkdtm/bugs.c
+++ b/drivers/misc/lkdtm/bugs.c
@@ -378,3 +378,39 @@ void lkdtm_DOUBLE_FAULT(void)
pr_err("XFAIL: this test is ia32-only\n");
#endif
}
+
+#ifdef CONFIG_ARM64_PTR_AUTH
+static noinline void change_pac_parameters(void)
+{
+ /* Reset the keys of current task */
+ ptrauth_thread_init_kernel(current);
+ ptrauth_thread_switch_kernel(current);
+}
+
+#define CORRUPT_PAC_ITERATE 10
+noinline void lkdtm_CORRUPT_PAC(void)
+{
+ int i;
+
+ if (!system_supports_address_auth()) {
+ pr_err("FAIL: arm64 pointer authentication feature not present\n");
+ return;
+ }
+
+ pr_info("Change the PAC parameters to force function return failure\n");
+ /*
+ * Pac is a hash value computed from input keys, return address and
+ * stack pointer. As pac has fewer bits so there is a chance of
+ * collision, so iterate few times to reduce the collision probability.
+ */
+ for (i = 0; i < CORRUPT_PAC_ITERATE; i++)
+ change_pac_parameters();
+
+ pr_err("FAIL: %s test failed. Kernel may be unstable from here\n", __func__);
+}
+#else /* !CONFIG_ARM64_PTR_AUTH */
+noinline void lkdtm_CORRUPT_PAC(void)
+{
+ pr_err("FAIL: arm64 pointer authentication config disabled\n");
+}
+#endif
diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
index ee0d6e7..5ce4ac8 100644
--- a/drivers/misc/lkdtm/core.c
+++ b/drivers/misc/lkdtm/core.c
@@ -116,6 +116,7 @@ static const struct crashtype crashtypes[] = {
CRASHTYPE(STACK_GUARD_PAGE_LEADING),
CRASHTYPE(STACK_GUARD_PAGE_TRAILING),
CRASHTYPE(UNSET_SMEP),
+ CRASHTYPE(CORRUPT_PAC),
CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),
CRASHTYPE(OVERWRITE_ALLOCATION),
CRASHTYPE(WRITE_AFTER_FREE),
diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h
index c56d23e..8d13d01 100644
--- a/drivers/misc/lkdtm/lkdtm.h
+++ b/drivers/misc/lkdtm/lkdtm.h
@@ -31,6 +31,7 @@ void lkdtm_UNSET_SMEP(void);
#ifdef CONFIG_X86_32
void lkdtm_DOUBLE_FAULT(void);
#endif
+void lkdtm_CORRUPT_PAC(void);
/* lkdtm_heap.c */
void __init lkdtm_heap_init(void);
--
2.7.4
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