From: Ram Pai <linuxram@us.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au,
khandual@linux.vnet.ibm.com, aneesh.kumar@linux.vnet.ibm.com,
bsingharora@gmail.com, hbabu@us.ibm.com, linuxram@us.ibm.com,
bauerman@linux.vnet.ibm.com, mhocko@kernel.org
Subject: [RFC v7 10/25] powerpc: introduce execute-only pkey
Date: Sun, 30 Jul 2017 17:12:11 -0700 [thread overview]
Message-ID: <1501459946-11619-11-git-send-email-linuxram@us.ibm.com> (raw)
In-Reply-To: <1501459946-11619-1-git-send-email-linuxram@us.ibm.com>
This patch provides the implementation of execute-only pkey.
The architecture-independent expects the ability to create
and manage a special key which has execute-only permission.
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
arch/powerpc/include/asm/book3s/64/mmu.h | 1 +
arch/powerpc/include/asm/pkeys.h | 8 ++++-
arch/powerpc/mm/pkeys.c | 57 ++++++++++++++++++++++++++++++
3 files changed, 65 insertions(+), 1 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h
index 104ad72..0c0a2a8 100644
--- a/arch/powerpc/include/asm/book3s/64/mmu.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu.h
@@ -116,6 +116,7 @@ struct patb_entry {
* bit unset -> key available for allocation
*/
u32 pkey_allocation_map;
+ s16 execute_only_pkey; /* key holding execute-only protection */
#endif
} mm_context_t;
diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index dac8751..5b17d93 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h
@@ -126,11 +126,15 @@ static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
* Try to dedicate one of the protection keys to be used as an
* execute-only protection key.
*/
+extern int __execute_only_pkey(struct mm_struct *mm);
static inline int execute_only_pkey(struct mm_struct *mm)
{
- return 0;
+ if (!pkey_inited)
+ return -1;
+ return __execute_only_pkey(mm);
}
+
static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
int prot, int pkey)
{
@@ -157,6 +161,8 @@ static inline void pkey_mm_init(struct mm_struct *mm)
if (!pkey_inited)
return;
mm_pkey_allocation_map(mm) = initial_allocation_mask;
+ /* -1 means unallocated or invalid */
+ mm->context.execute_only_pkey = -1;
}
static inline void pkey_initialize(void)
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index c1c40c3..25749bf 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c
@@ -97,3 +97,60 @@ int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
init_iamr(pkey, new_iamr_bits);
return 0;
}
+
+static inline bool pkey_allows_readwrite(int pkey)
+{
+ int pkey_shift = pkeyshift(pkey);
+
+ if (!(read_uamor() & (0x3UL << pkey_shift)))
+ return true;
+
+ return !(read_amr() & ((AMR_RD_BIT|AMR_WR_BIT) << pkey_shift));
+}
+
+int __execute_only_pkey(struct mm_struct *mm)
+{
+ bool need_to_set_mm_pkey = false;
+ int execute_only_pkey = mm->context.execute_only_pkey;
+ int ret;
+
+ /* Do we need to assign a pkey for mm's execute-only maps? */
+ if (execute_only_pkey == -1) {
+ /* Go allocate one to use, which might fail */
+ execute_only_pkey = mm_pkey_alloc(mm);
+ if (execute_only_pkey < 0)
+ return -1;
+ need_to_set_mm_pkey = true;
+ }
+
+ /*
+ * We do not want to go through the relatively costly
+ * dance to set AMR if we do not need to. Check it
+ * first and assume that if the execute-only pkey is
+ * readwrite-disabled than we do not have to set it
+ * ourselves.
+ */
+ if (!need_to_set_mm_pkey &&
+ !pkey_allows_readwrite(execute_only_pkey))
+ return execute_only_pkey;
+
+ /*
+ * Set up AMR so that it denies access for everything
+ * other than execution.
+ */
+ ret = __arch_set_user_pkey_access(current, execute_only_pkey,
+ (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE));
+ /*
+ * If the AMR-set operation failed somehow, just return
+ * 0 and effectively disable execute-only support.
+ */
+ if (ret) {
+ mm_set_pkey_free(mm, execute_only_pkey);
+ return -1;
+ }
+
+ /* We got one, store it and use it from here on out */
+ if (need_to_set_mm_pkey)
+ mm->context.execute_only_pkey = execute_only_pkey;
+ return execute_only_pkey;
+}
--
1.7.1
next prev parent reply other threads:[~2017-07-31 0:12 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-31 0:12 [RFC v7 00/25] powerpc: Memory Protection Keys Ram Pai
2017-07-31 0:12 ` [RFC v7 01/25] powerpc: define an additional vma bit for protection keys Ram Pai
2017-07-31 0:12 ` [RFC v7 02/25] powerpc: track allocation status of all pkeys Ram Pai
2017-08-10 20:25 ` Thiago Jung Bauermann
2017-08-11 5:39 ` Michael Ellerman
2017-08-17 16:00 ` Ram Pai
2017-08-17 15:48 ` Ram Pai
2017-08-17 20:40 ` Thiago Jung Bauermann
2017-10-18 2:42 ` Balbir Singh
2017-10-18 3:40 ` Ram Pai
2017-10-18 16:08 ` Laurent Dufour
2017-10-18 22:04 ` Ram Pai
2017-07-31 0:12 ` [RFC v7 03/25] powerpc: helper function to read, write AMR, IAMR, UAMOR registers Ram Pai
2017-07-31 0:12 ` [RFC v7 04/25] powerpc: helper functions to initialize AMR, IAMR and " Ram Pai
2017-07-31 0:12 ` [RFC v7 05/25] powerpc: cleaup AMR, iAMR when a key is allocated or freed Ram Pai
2017-07-31 0:12 ` [RFC v7 06/25] powerpc: implementation for arch_set_user_pkey_access() Ram Pai
2017-07-31 0:12 ` [RFC v7 07/25] powerpc: sys_pkey_alloc() and sys_pkey_free() system calls Ram Pai
2017-07-31 0:12 ` [RFC v7 08/25] powerpc: ability to create execute-disabled pkeys Ram Pai
2017-07-31 0:12 ` [RFC v7 09/25] powerpc: store and restore the pkey state across context switches Ram Pai
2017-08-10 20:46 ` Thiago Jung Bauermann
2017-08-11 6:34 ` Michael Ellerman
2017-08-17 16:41 ` Ram Pai
2017-07-31 0:12 ` Ram Pai [this message]
2017-07-31 0:12 ` [RFC v7 11/25] powerpc: ability to associate pkey to a vma Ram Pai
2017-07-31 0:12 ` [RFC v7 12/25] powerpc: implementation for arch_override_mprotect_pkey() Ram Pai
2017-10-18 15:58 ` Laurent Dufour
2017-10-18 21:37 ` Ram Pai
2017-07-31 0:12 ` [RFC v7 13/25] powerpc: map vma key-protection bits to pte key bits Ram Pai
2017-07-31 0:12 ` [RFC v7 14/25] powerpc: sys_pkey_mprotect() system call Ram Pai
2017-07-31 0:12 ` [RFC v7 15/25] powerpc: Program HPTE key protection bits Ram Pai
2017-10-18 16:15 ` Laurent Dufour
2017-10-18 22:12 ` Ram Pai
2017-10-19 5:12 ` Michael Ellerman
2017-07-31 0:12 ` [RFC v7 16/25] powerpc: helper to validate key-access permissions of a pte Ram Pai
2017-10-18 16:08 ` Laurent Dufour
2017-10-18 21:56 ` Ram Pai
2017-10-19 5:13 ` Michael Ellerman
2017-07-31 0:12 ` [RFC v7 17/25] powerpc: check key protection for user page access Ram Pai
2017-07-31 0:12 ` [RFC v7 18/25] powerpc: Macro the mask used for checking DSI exception Ram Pai
2017-07-31 0:12 ` [RFC v7 19/25] powerpc: implementation for arch_vma_access_permitted() Ram Pai
2017-07-31 0:12 ` [RFC v7 20/25] powerpc: Handle exceptions caused by pkey violation Ram Pai
2017-07-31 0:12 ` [RFC v7 21/25] powerpc: capture AMR register content on " Ram Pai
2017-07-31 0:12 ` [RFC v7 22/25] powerpc: introduce get_pte_pkey() helper Ram Pai
2017-07-31 0:12 ` [RFC v7 23/25] powerpc: capture the violated protection key on fault Ram Pai
2017-07-31 0:12 ` [RFC v7 24/25] powerpc: Deliver SEGV signal on pkey violation Ram Pai
2017-08-10 21:00 ` Thiago Jung Bauermann
2017-08-11 10:26 ` Michael Ellerman
2017-08-17 17:14 ` Ram Pai
2017-08-18 4:48 ` Michael Ellerman
2017-08-18 17:04 ` Ram Pai
2017-08-18 21:54 ` Benjamin Herrenschmidt
2017-08-18 22:36 ` Ram Pai
2017-10-18 2:25 ` Balbir Singh
2017-10-18 3:01 ` Ram Pai
2017-08-18 22:49 ` Ram Pai
2017-08-19 8:23 ` Benjamin Herrenschmidt
2017-07-31 0:12 ` [RFC v7 25/25] powerpc: Enable pkey subsystem Ram Pai
2017-08-10 21:27 ` Thiago Jung Bauermann
2017-08-17 17:40 ` Ram Pai
2017-08-17 20:30 ` Thiago Jung Bauermann
2017-08-17 23:48 ` Ram Pai
2017-08-18 5:07 ` Michael Ellerman
2017-08-18 15:26 ` Thiago Jung Bauermann
2017-08-18 16:32 ` Ram Pai
2017-08-11 17:34 ` [RFC v7 26/25] mm/mprotect, powerpc/mm/pkeys, x86/mm/pkeys: Add sysfs interface Thiago Jung Bauermann
2017-08-18 0:25 ` Ram Pai
2017-08-18 23:19 ` Thiago Jung Bauermann
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