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>

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 446f8e5f10d98b5a26fe047207a3d71ce7352671..0c5d6d06107decd374020fac0cd4412ca4bd041f 100644 (file)
--- 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;