diff mbox series

[v2,18/28] powerpc/book3s64/kuap: Restrict access to userspace based on userspace AMR

Message ID 20200502112229.545331-19-aneesh.kumar@linux.ibm.com (mailing list archive)
State Superseded
Headers show
Series Kernel userspace access/execution prevention with hash translation | expand

Checks

Context Check Description
snowpatch_ozlabs/apply_patch warning Failed to apply on branch powerpc/merge (1bc92fe3175eb26ff37e580c0383d7a9abe06835)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch powerpc/next (45591da765885f7320a111d290b3a28a23eed359)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch linus/master (690e2aba7beb1ef06352803bea41a68a3c695015)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch powerpc/fixes (5990cdee689c6885b27c6d969a3d58b09002b0bc)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch linux-next (fb9d670f57e3f6478602328bbbf71138be06ca4f)
snowpatch_ozlabs/apply_patch fail Failed to apply to any branch

Commit Message

Aneesh Kumar K V May 2, 2020, 11:22 a.m. UTC 
If an application has configured address protection such that read/write is
denied using pkey even the kernel should receive a FAULT on accessing the same.

This patch use user AMR value stored in pt_regs.kuap to achieve the same.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
 arch/powerpc/include/asm/book3s/64/kup.h | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h
index 31eb0acddea9..f097d69ec2c8 100644
--- a/arch/powerpc/include/asm/book3s/64/kup.h
+++ b/arch/powerpc/include/asm/book3s/64/kup.h
@@ -279,14 +279,20 @@  static inline void set_kuap(unsigned long value)
 static __always_inline void allow_user_access(void __user *to, const void __user *from,
 					      unsigned long size, unsigned long dir)
 {
+	unsigned long thread_amr = 0;
+
 	// This is written so we can resolve to a single case at build time
 	BUILD_BUG_ON(!__builtin_constant_p(dir));
+
+	if (mmu_has_feature(MMU_FTR_PKEY))
+		thread_amr = current_thread_amr();
+
 	if (dir == KUAP_READ)
-		set_kuap(AMR_KUAP_BLOCK_WRITE);
+		set_kuap(thread_amr | AMR_KUAP_BLOCK_WRITE);
 	else if (dir == KUAP_WRITE)
-		set_kuap(AMR_KUAP_BLOCK_READ);
+		set_kuap(thread_amr | AMR_KUAP_BLOCK_READ);
 	else if (dir == KUAP_READ_WRITE)
-		set_kuap(0);
+		set_kuap(thread_amr);
 	else
 		BUILD_BUG();
 }