* [kernel-hardening][PATCH v3 3/3] arm: mm: dump: add checking for writable and executable pages
@ 2017-12-04 14:27 Jinbum Park
2017-12-05 23:51 ` Laura Abbott
0 siblings, 1 reply; 3+ messages in thread
From: Jinbum Park @ 2017-12-04 14:27 UTC (permalink / raw)
To: linux-arm-kernel, linux-kernel, kernel-hardening
Cc: afzal.mohd.ma, mark.rutland, labbott, linux, gregkh, keescook,
vladimir.murzin, arnd
Page mappings with full RWX permissions are a security risk.
x86, arm64 has an option to walk the page tables
and dump any bad pages.
(1404d6f13e47
("arm64: dump: Add checking for writable and exectuable pages"))
Add a similar implementation for arm.
Signed-off-by: Jinbum Park <jinb.park7@gmail.com>
---
v3: Reuse pg_level, prot_bits to check ro, nx prot.
arch/arm/Kconfig.debug | 27 +++++++++++++++++++++++
arch/arm/include/asm/ptdump.h | 8 +++++++
arch/arm/mm/dump.c | 51 +++++++++++++++++++++++++++++++++++++++++++
arch/arm/mm/init.c | 2 ++
4 files changed, 88 insertions(+)
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index e7b94db..78a6470 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -20,6 +20,33 @@ config ARM_PTDUMP_DEBUGFS
kernel.
If in doubt, say "N"
+config DEBUG_WX
+ bool "Warn on W+X mappings at boot"
+ select ARM_PTDUMP_CORE
+ ---help---
+ Generate a warning if any W+X mappings are found at boot.
+
+ This is useful for discovering cases where the kernel is leaving
+ W+X mappings after applying NX, as such mappings are a security risk.
+
+ Look for a message in dmesg output like this:
+
+ arm/mm: Checked W+X mappings: passed, no W+X pages found.
+
+ or like this, if the check failed:
+
+ arm/mm: Checked W+X mappings: FAILED, <N> W+X pages found.
+
+ Note that even if the check fails, your kernel is possibly
+ still fine, as W+X mappings are not a security hole in
+ themselves, what they do is that they make the exploitation
+ of other unfixed kernel bugs easier.
+
+ There is no runtime or memory usage effect of this option
+ once the kernel has booted up - it's a one time check.
+
+ If in doubt, say "Y".
+
# RMK wants arm kernels compiled with frame pointers or stack unwinding.
# If you know what you are doing and are willing to live without stack
# traces, you can get a slightly smaller kernel by setting this option to
diff --git a/arch/arm/include/asm/ptdump.h b/arch/arm/include/asm/ptdump.h
index 3a6c0b7..b6a0162 100644
--- a/arch/arm/include/asm/ptdump.h
+++ b/arch/arm/include/asm/ptdump.h
@@ -43,6 +43,14 @@ static inline int ptdump_debugfs_register(struct ptdump_info *info,
}
#endif /* CONFIG_ARM_PTDUMP_DEBUGFS */
+void ptdump_check_wx(void);
+
#endif /* CONFIG_ARM_PTDUMP_CORE */
+#ifdef CONFIG_DEBUG_WX
+#define debug_checkwx() ptdump_check_wx()
+#else
+#define debug_checkwx() do { } while (0)
+#endif
+
#endif /* __ASM_PTDUMP_H */
diff --git a/arch/arm/mm/dump.c b/arch/arm/mm/dump.c
index 43a2bee..3e2e6f0 100644
--- a/arch/arm/mm/dump.c
+++ b/arch/arm/mm/dump.c
@@ -52,6 +52,8 @@ struct pg_state {
unsigned long start_address;
unsigned level;
u64 current_prot;
+ bool check_wx;
+ unsigned long wx_pages;
const char *current_domain;
};
@@ -194,6 +196,8 @@ struct pg_level {
const struct prot_bits *bits;
size_t num;
u64 mask;
+ const struct prot_bits *ro_bit;
+ const struct prot_bits *nx_bit;
};
static struct pg_level pg_level[] = {
@@ -203,9 +207,17 @@ struct pg_level {
}, { /* pmd */
.bits = section_bits,
.num = ARRAY_SIZE(section_bits),
+ #ifdef CONFIG_ARM_LPAE
+ .ro_bit = section_bits + 1,
+ #else
+ .ro_bit = section_bits,
+ #endif
+ .nx_bit = section_bits + ARRAY_SIZE(section_bits) - 2,
}, { /* pte */
.bits = pte_bits,
.num = ARRAY_SIZE(pte_bits),
+ .ro_bit = pte_bits + 1,
+ .nx_bit = pte_bits + 2,
},
};
@@ -226,6 +238,23 @@ static void dump_prot(struct pg_state *st, const struct prot_bits *bits, size_t
}
}
+static void note_prot_wx(struct pg_state *st, unsigned long addr)
+{
+ if (!st->check_wx)
+ return;
+ if ((st->current_prot & pg_level[st->level].ro_bit->mask) ==
+ pg_level[st->level].ro_bit->val)
+ return;
+ if ((st->current_prot & pg_level[st->level].nx_bit->mask) ==
+ pg_level[st->level].nx_bit->val)
+ return;
+
+ WARN_ONCE(1, "arm/mm: Found insecure W+X mapping at address %p/%pS\n",
+ (void *)st->start_address, (void *)st->start_address);
+
+ st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
+}
+
static void note_page(struct pg_state *st, unsigned long addr,
unsigned int level, u64 val, const char *domain)
{
@@ -244,6 +273,7 @@ static void note_page(struct pg_state *st, unsigned long addr,
unsigned long delta;
if (st->current_prot) {
+ note_prot_wx(st, addr);
pt_dump_seq_printf(st->seq, "0x%08lx-0x%08lx ",
st->start_address, addr);
@@ -367,6 +397,7 @@ void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info)
struct pg_state st = {
.seq = m,
.marker = info->markers,
+ .check_wx = false,
};
walk_pgd(&st, info->mm, info->base_addr);
@@ -391,6 +422,26 @@ static void ptdump_initialize(void)
.base_addr = 0,
};
+void ptdump_check_wx(void)
+{
+ struct pg_state st = {
+ .seq = NULL,
+ .marker = (struct addr_marker[]) {
+ { 0, NULL},
+ { -1, NULL},
+ },
+ .check_wx = true,
+ };
+
+ walk_pgd(&st, &init_mm, 0);
+ note_page(&st, 0, 0, 0, NULL);
+ if (st.wx_pages)
+ pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n",
+ st.wx_pages);
+ else
+ pr_info("Checked W+X mappings: passed, no W+X pages found\n");
+}
+
static int ptdump_init(void)
{
ptdump_initialize();
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index a1f11a7..bd6f451 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -36,6 +36,7 @@
#include <asm/system_info.h>
#include <asm/tlb.h>
#include <asm/fixmap.h>
+#include <asm/ptdump.h>
#include <asm/mach/arch.h>
#include <asm/mach/map.h>
@@ -738,6 +739,7 @@ static int __mark_rodata_ro(void *unused)
void mark_rodata_ro(void)
{
stop_machine(__mark_rodata_ro, NULL, NULL);
+ debug_checkwx();
}
void set_kernel_text_rw(void)
--
1.9.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [kernel-hardening][PATCH v3 3/3] arm: mm: dump: add checking for writable and executable pages
2017-12-04 14:27 [kernel-hardening][PATCH v3 3/3] arm: mm: dump: add checking for writable and executable pages Jinbum Park
@ 2017-12-05 23:51 ` Laura Abbott
2017-12-06 9:17 ` Jinbum Park
0 siblings, 1 reply; 3+ messages in thread
From: Laura Abbott @ 2017-12-05 23:51 UTC (permalink / raw)
To: Jinbum Park, linux-arm-kernel, linux-kernel, kernel-hardening
Cc: afzal.mohd.ma, mark.rutland, linux, gregkh, keescook,
vladimir.murzin, arnd
On 12/04/2017 06:27 AM, Jinbum Park wrote:
> Page mappings with full RWX permissions are a security risk.
> x86, arm64 has an option to walk the page tables
> and dump any bad pages.
>
> (1404d6f13e47
> ("arm64: dump: Add checking for writable and exectuable pages"))
> Add a similar implementation for arm.
>
> Signed-off-by: Jinbum Park <jinb.park7@gmail.com>
> ---
> v3: Reuse pg_level, prot_bits to check ro, nx prot.
>
> arch/arm/Kconfig.debug | 27 +++++++++++++++++++++++
> arch/arm/include/asm/ptdump.h | 8 +++++++
> arch/arm/mm/dump.c | 51 +++++++++++++++++++++++++++++++++++++++++++
> arch/arm/mm/init.c | 2 ++
> 4 files changed, 88 insertions(+)
>
> diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
> index e7b94db..78a6470 100644
> --- a/arch/arm/Kconfig.debug
> +++ b/arch/arm/Kconfig.debug
> @@ -20,6 +20,33 @@ config ARM_PTDUMP_DEBUGFS
> kernel.
> If in doubt, say "N"
>
> +config DEBUG_WX
> + bool "Warn on W+X mappings at boot"
> + select ARM_PTDUMP_CORE
> + ---help---
> + Generate a warning if any W+X mappings are found at boot.
> +
> + This is useful for discovering cases where the kernel is leaving
> + W+X mappings after applying NX, as such mappings are a security risk.
> +
> + Look for a message in dmesg output like this:
> +
> + arm/mm: Checked W+X mappings: passed, no W+X pages found.
> +
> + or like this, if the check failed:
> +
> + arm/mm: Checked W+X mappings: FAILED, <N> W+X pages found.
> +
> + Note that even if the check fails, your kernel is possibly
> + still fine, as W+X mappings are not a security hole in
> + themselves, what they do is that they make the exploitation
> + of other unfixed kernel bugs easier.
> +
> + There is no runtime or memory usage effect of this option
> + once the kernel has booted up - it's a one time check.
> +
> + If in doubt, say "Y".
> +
> # RMK wants arm kernels compiled with frame pointers or stack unwinding.
> # If you know what you are doing and are willing to live without stack
> # traces, you can get a slightly smaller kernel by setting this option to
> diff --git a/arch/arm/include/asm/ptdump.h b/arch/arm/include/asm/ptdump.h
> index 3a6c0b7..b6a0162 100644
> --- a/arch/arm/include/asm/ptdump.h
> +++ b/arch/arm/include/asm/ptdump.h
> @@ -43,6 +43,14 @@ static inline int ptdump_debugfs_register(struct ptdump_info *info,
> }
> #endif /* CONFIG_ARM_PTDUMP_DEBUGFS */
>
> +void ptdump_check_wx(void);
> +
> #endif /* CONFIG_ARM_PTDUMP_CORE */
>
> +#ifdef CONFIG_DEBUG_WX
> +#define debug_checkwx() ptdump_check_wx()
> +#else
> +#define debug_checkwx() do { } while (0)
> +#endif
> +
> #endif /* __ASM_PTDUMP_H */
> diff --git a/arch/arm/mm/dump.c b/arch/arm/mm/dump.c
> index 43a2bee..3e2e6f0 100644
> --- a/arch/arm/mm/dump.c
> +++ b/arch/arm/mm/dump.c
> @@ -52,6 +52,8 @@ struct pg_state {
> unsigned long start_address;
> unsigned level;
> u64 current_prot;
> + bool check_wx;
> + unsigned long wx_pages;
> const char *current_domain;
> };
>
> @@ -194,6 +196,8 @@ struct pg_level {
> const struct prot_bits *bits;
> size_t num;
> u64 mask;
> + const struct prot_bits *ro_bit;
> + const struct prot_bits *nx_bit;
> };
>
> static struct pg_level pg_level[] = {
> @@ -203,9 +207,17 @@ struct pg_level {
> }, { /* pmd */
> .bits = section_bits,
> .num = ARRAY_SIZE(section_bits),
> + #ifdef CONFIG_ARM_LPAE
> + .ro_bit = section_bits + 1,
> + #else
> + .ro_bit = section_bits,
> + #endif
> + .nx_bit = section_bits + ARRAY_SIZE(section_bits) - 2,
> }, { /* pte */
> .bits = pte_bits,
> .num = ARRAY_SIZE(pte_bits),
> + .ro_bit = pte_bits + 1,
> + .nx_bit = pte_bits + 2,
> },
> };
>
This is better but the addition offset from the array is still
prone to breakage if we add entries. Maybe something like this
on top of yours:
diff --git a/arch/arm/mm/dump.c b/arch/arm/mm/dump.c
index 3e2e6f06e4d9..572cbc4dc247 100644
--- a/arch/arm/mm/dump.c
+++ b/arch/arm/mm/dump.c
@@ -62,6 +62,8 @@ struct prot_bits {
u64 val;
const char *set;
const char *clear;
+ bool ro_bit;
+ bool x_bit;
};
static const struct prot_bits pte_bits[] = {
@@ -75,11 +77,13 @@ static const struct prot_bits pte_bits[] = {
.val = L_PTE_RDONLY,
.set = "ro",
.clear = "RW",
+ .ro_bit = true,
}, {
.mask = L_PTE_XN,
.val = L_PTE_XN,
.set = "NX",
.clear = "x ",
+ .x_bit = true,
}, {
.mask = L_PTE_SHARED,
.val = L_PTE_SHARED,
@@ -143,11 +147,13 @@ static const struct prot_bits section_bits[] = {
.val = L_PMD_SECT_RDONLY | PMD_SECT_AP2,
.set = "ro",
.clear = "RW",
+ .ro_bit = true,
#elif __LINUX_ARM_ARCH__ >= 6
{
.mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = PMD_SECT_APX | PMD_SECT_AP_WRITE,
.set = " ro",
+ .ro_bit = true,
}, {
.mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = PMD_SECT_AP_WRITE,
@@ -166,6 +172,7 @@ static const struct prot_bits section_bits[] = {
.mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = 0,
.set = " ro",
+ .ro_bit = true,
}, {
.mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = PMD_SECT_AP_WRITE,
@@ -184,6 +191,7 @@ static const struct prot_bits section_bits[] = {
.val = PMD_SECT_XN,
.set = "NX",
.clear = "x ",
+ .x_bit = true,
}, {
.mask = PMD_SECT_S,
.val = PMD_SECT_S,
@@ -207,17 +215,9 @@ static struct pg_level pg_level[] = {
}, { /* pmd */
.bits = section_bits,
.num = ARRAY_SIZE(section_bits),
- #ifdef CONFIG_ARM_LPAE
- .ro_bit = section_bits + 1,
- #else
- .ro_bit = section_bits,
- #endif
- .nx_bit = section_bits + ARRAY_SIZE(section_bits) - 2,
}, { /* pte */
.bits = pte_bits,
.num = ARRAY_SIZE(pte_bits),
- .ro_bit = pte_bits + 1,
- .nx_bit = pte_bits + 2,
},
};
@@ -410,8 +410,13 @@ static void ptdump_initialize(void)
for (i = 0; i < ARRAY_SIZE(pg_level); i++)
if (pg_level[i].bits)
- for (j = 0; j < pg_level[i].num; j++)
+ for (j = 0; j < pg_level[i].num; j++) {
pg_level[i].mask |= pg_level[i].bits[j].mask;
+ if (pg_level[i].bits[j].ro_bit)
+ pg_level[i].ro_bit = &pg_level[i].bits[j];
+ if (pg_level[i].bits[j].x_bit)
+ pg_level[i].nx_bit = &pg_level[i].bits[j];
+ }
address_markers[2].start_address = VMALLOC_START;
}
> @@ -226,6 +238,23 @@ static void dump_prot(struct pg_state *st, const struct prot_bits *bits, size_t
> }
> }
>
> +static void note_prot_wx(struct pg_state *st, unsigned long addr)
> +{
> + if (!st->check_wx)
> + return;
> + if ((st->current_prot & pg_level[st->level].ro_bit->mask) ==
> + pg_level[st->level].ro_bit->val)
> + return;
> + if ((st->current_prot & pg_level[st->level].nx_bit->mask) ==
> + pg_level[st->level].nx_bit->val)
> + return;
> +
> + WARN_ONCE(1, "arm/mm: Found insecure W+X mapping at address %p/%pS\n",
> + (void *)st->start_address, (void *)st->start_address);
> +
With the new %p hashing, printing just %p is not useful, so just drop
it and just have the %pS.
Thanks,
Laura
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [kernel-hardening][PATCH v3 3/3] arm: mm: dump: add checking for writable and executable pages
2017-12-05 23:51 ` Laura Abbott
@ 2017-12-06 9:17 ` Jinbum Park
0 siblings, 0 replies; 3+ messages in thread
From: Jinbum Park @ 2017-12-06 9:17 UTC (permalink / raw)
To: Laura Abbott
Cc: linux-arm-kernel, LKML, kernel-hardening, Afzal Mohammed,
Mark Rutland, linux, gregkh, Kees Cook, vladimir.murzin,
Arnd Bergmann
2017-12-06 8:51 GMT+09:00 Laura Abbott <labbott@redhat.com>:
> On 12/04/2017 06:27 AM, Jinbum Park wrote:
>>
>> Page mappings with full RWX permissions are a security risk.
>> x86, arm64 has an option to walk the page tables
>> and dump any bad pages.
>>
>> (1404d6f13e47
>> ("arm64: dump: Add checking for writable and exectuable pages"))
>> Add a similar implementation for arm.
>>
>> Signed-off-by: Jinbum Park <jinb.park7@gmail.com>
>> ---
>> v3: Reuse pg_level, prot_bits to check ro, nx prot.
>>
>> arch/arm/Kconfig.debug | 27 +++++++++++++++++++++++
>> arch/arm/include/asm/ptdump.h | 8 +++++++
>> arch/arm/mm/dump.c | 51
>> +++++++++++++++++++++++++++++++++++++++++++
>> arch/arm/mm/init.c | 2 ++
>> 4 files changed, 88 insertions(+)
>>
>> diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
>> index e7b94db..78a6470 100644
>> --- a/arch/arm/Kconfig.debug
>> +++ b/arch/arm/Kconfig.debug
>> @@ -20,6 +20,33 @@ config ARM_PTDUMP_DEBUGFS
>> kernel.
>> If in doubt, say "N"
>> +config DEBUG_WX
>> + bool "Warn on W+X mappings at boot"
>> + select ARM_PTDUMP_CORE
>> + ---help---
>> + Generate a warning if any W+X mappings are found at boot.
>> +
>> + This is useful for discovering cases where the kernel is
>> leaving
>> + W+X mappings after applying NX, as such mappings are a
>> security risk.
>> +
>> + Look for a message in dmesg output like this:
>> +
>> + arm/mm: Checked W+X mappings: passed, no W+X pages
>> found.
>> +
>> + or like this, if the check failed:
>> +
>> + arm/mm: Checked W+X mappings: FAILED, <N> W+X
>> pages found.
>> +
>> + Note that even if the check fails, your kernel is possibly
>> + still fine, as W+X mappings are not a security hole in
>> + themselves, what they do is that they make the
>> exploitation
>> + of other unfixed kernel bugs easier.
>> +
>> + There is no runtime or memory usage effect of this option
>> + once the kernel has booted up - it's a one time check.
>> +
>> + If in doubt, say "Y".
>> +
>> # RMK wants arm kernels compiled with frame pointers or stack unwinding.
>> # If you know what you are doing and are willing to live without stack
>> # traces, you can get a slightly smaller kernel by setting this option
>> to
>> diff --git a/arch/arm/include/asm/ptdump.h b/arch/arm/include/asm/ptdump.h
>> index 3a6c0b7..b6a0162 100644
>> --- a/arch/arm/include/asm/ptdump.h
>> +++ b/arch/arm/include/asm/ptdump.h
>> @@ -43,6 +43,14 @@ static inline int ptdump_debugfs_register(struct
>> ptdump_info *info,
>> }
>> #endif /* CONFIG_ARM_PTDUMP_DEBUGFS */
>> +void ptdump_check_wx(void);
>> +
>> #endif /* CONFIG_ARM_PTDUMP_CORE */
>> +#ifdef CONFIG_DEBUG_WX
>> +#define debug_checkwx() ptdump_check_wx()
>> +#else
>> +#define debug_checkwx() do { } while (0)
>> +#endif
>> +
>> #endif /* __ASM_PTDUMP_H */
>> diff --git a/arch/arm/mm/dump.c b/arch/arm/mm/dump.c
>> index 43a2bee..3e2e6f0 100644
>> --- a/arch/arm/mm/dump.c
>> +++ b/arch/arm/mm/dump.c
>> @@ -52,6 +52,8 @@ struct pg_state {
>> unsigned long start_address;
>> unsigned level;
>> u64 current_prot;
>> + bool check_wx;
>> + unsigned long wx_pages;
>> const char *current_domain;
>> };
>> @@ -194,6 +196,8 @@ struct pg_level {
>> const struct prot_bits *bits;
>> size_t num;
>> u64 mask;
>> + const struct prot_bits *ro_bit;
>> + const struct prot_bits *nx_bit;
>> };
It looks better~:)
I'll prepare new version.
>> static struct pg_level pg_level[] = {
>> @@ -203,9 +207,17 @@ struct pg_level {
>> }, { /* pmd */
>> .bits = section_bits,
>> .num = ARRAY_SIZE(section_bits),
>> + #ifdef CONFIG_ARM_LPAE
>> + .ro_bit = section_bits + 1,
>> + #else
>> + .ro_bit = section_bits,
>> + #endif
>> + .nx_bit = section_bits + ARRAY_SIZE(section_bits) - 2,
>> }, { /* pte */
>> .bits = pte_bits,
>> .num = ARRAY_SIZE(pte_bits),
>> + .ro_bit = pte_bits + 1,
>> + .nx_bit = pte_bits + 2,
>> },
>> };
>>
>
>
> This is better but the addition offset from the array is still
> prone to breakage if we add entries. Maybe something like this
> on top of yours:
>
> diff --git a/arch/arm/mm/dump.c b/arch/arm/mm/dump.c
> index 3e2e6f06e4d9..572cbc4dc247 100644
> --- a/arch/arm/mm/dump.c
> +++ b/arch/arm/mm/dump.c
> @@ -62,6 +62,8 @@ struct prot_bits {
> u64 val;
> const char *set;
> const char *clear;
> + bool ro_bit;
> + bool x_bit;
> };
> static const struct prot_bits pte_bits[] = {
> @@ -75,11 +77,13 @@ static const struct prot_bits pte_bits[] = {
> .val = L_PTE_RDONLY,
> .set = "ro",
> .clear = "RW",
> + .ro_bit = true,
> }, {
> .mask = L_PTE_XN,
> .val = L_PTE_XN,
> .set = "NX",
> .clear = "x ",
> + .x_bit = true,
> }, {
> .mask = L_PTE_SHARED,
> .val = L_PTE_SHARED,
> @@ -143,11 +147,13 @@ static const struct prot_bits section_bits[] = {
> .val = L_PMD_SECT_RDONLY | PMD_SECT_AP2,
> .set = "ro",
> .clear = "RW",
> + .ro_bit = true,
> #elif __LINUX_ARM_ARCH__ >= 6
> {
> .mask = PMD_SECT_APX | PMD_SECT_AP_READ |
> PMD_SECT_AP_WRITE,
> .val = PMD_SECT_APX | PMD_SECT_AP_WRITE,
> .set = " ro",
> + .ro_bit = true,
> }, {
> .mask = PMD_SECT_APX | PMD_SECT_AP_READ |
> PMD_SECT_AP_WRITE,
> .val = PMD_SECT_AP_WRITE,
> @@ -166,6 +172,7 @@ static const struct prot_bits section_bits[] = {
> .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
> .val = 0,
> .set = " ro",
> + .ro_bit = true,
> }, {
> .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
> .val = PMD_SECT_AP_WRITE,
> @@ -184,6 +191,7 @@ static const struct prot_bits section_bits[] = {
> .val = PMD_SECT_XN,
> .set = "NX",
> .clear = "x ",
> + .x_bit = true,
> }, {
> .mask = PMD_SECT_S,
> .val = PMD_SECT_S,
> @@ -207,17 +215,9 @@ static struct pg_level pg_level[] = {
> }, { /* pmd */
> .bits = section_bits,
> .num = ARRAY_SIZE(section_bits),
> - #ifdef CONFIG_ARM_LPAE
> - .ro_bit = section_bits + 1,
> - #else
> - .ro_bit = section_bits,
> - #endif
> - .nx_bit = section_bits + ARRAY_SIZE(section_bits) - 2,
> }, { /* pte */
> .bits = pte_bits,
> .num = ARRAY_SIZE(pte_bits),
> - .ro_bit = pte_bits + 1,
> - .nx_bit = pte_bits + 2,
> },
> };
> @@ -410,8 +410,13 @@ static void ptdump_initialize(void)
> for (i = 0; i < ARRAY_SIZE(pg_level); i++)
> if (pg_level[i].bits)
> - for (j = 0; j < pg_level[i].num; j++)
> + for (j = 0; j < pg_level[i].num; j++) {
> pg_level[i].mask |=
> pg_level[i].bits[j].mask;
> + if (pg_level[i].bits[j].ro_bit)
> + pg_level[i].ro_bit =
> &pg_level[i].bits[j];
> + if (pg_level[i].bits[j].x_bit)
> + pg_level[i].nx_bit =
> &pg_level[i].bits[j];
> + }
> address_markers[2].start_address = VMALLOC_START;
> }
>
>
>
>
>>
>> @@ -226,6 +238,23 @@ static void dump_prot(struct pg_state *st, const
>> struct prot_bits *bits, size_t
>> }
>> }
>> +static void note_prot_wx(struct pg_state *st, unsigned long addr)
>> +{
>> + if (!st->check_wx)
>> + return;
>> + if ((st->current_prot & pg_level[st->level].ro_bit->mask) ==
>> + pg_level[st->level].ro_bit->val)
>> + return;
>> + if ((st->current_prot & pg_level[st->level].nx_bit->mask) ==
>> + pg_level[st->level].nx_bit->val)
>> + return;
>> +
>> + WARN_ONCE(1, "arm/mm: Found insecure W+X mapping at address
>> %p/%pS\n",
>> + (void *)st->start_address, (void *)st->start_address);
>> +
>
>
> With the new %p hashing, printing just %p is not useful, so just drop
> it and just have the %pS.
ok, I'll drop the %p.
>
> Thanks,
> Laura
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2017-12-06 9:17 UTC | newest]
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2017-12-04 14:27 [kernel-hardening][PATCH v3 3/3] arm: mm: dump: add checking for writable and executable pages Jinbum Park
2017-12-05 23:51 ` Laura Abbott
2017-12-06 9:17 ` Jinbum Park
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