From 4a2dd02b09160ee43f96c759fafa7b56dfc33816 Mon Sep 17 00:00:00 2001
From: Pedro Falcato <pedro.falcato@gmail.com>
Date: Sat, 17 Aug 2024 01:18:30 +0100
Subject: [PATCH] mm/mprotect: replace can_modify_mm with can_modify_vma
Avoid taking an extra trip down the mmap tree by checking the vmas
directly. mprotect (per POSIX) tolerates partial failure.
Link: https://lkml.kernel.org/r/20240817-mseal-depessimize-v3-3-d8d2e037df30@gmail.com
Signed-off-by: Pedro Falcato <pedro.falcato@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Jeff Xu <jeffxu@chromium.org>
Cc: Kees Cook <kees@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/mprotect.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 446f8e5f10d98..0c5d6d06107de 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -611,6 +611,9 @@ mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
unsigned long charged = 0;
int error;
+ if (!can_modify_vma(vma))
+ return -EPERM;
+
if (newflags == oldflags) {
*pprev = vma;
return 0;
@@ -769,15 +772,6 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
}
}
- /*
- * checking if memory is sealed.
- * can_modify_mm assumes we have acquired the lock on MM.
- */
- if (unlikely(!can_modify_mm(current->mm, start, end))) {
- error = -EPERM;
- goto out;
- }
-
prev = vma_prev(&vmi);
if (start > vma->vm_start)
prev = vma;
--
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