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| author | Pedro Falcato <pedro.falcato@gmail.com> | 2024-08-17 01:18:32 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-09-03 21:15:41 -0700 |
| commit | 23c57d1fa2b9530e38f7964b4e457fed5a7a0ae8 (patch) | |
| tree | 18ea09d6de61f1054f67568a06878502faa98ba2 /mm/madvise.c | |
| parent | 38075679b5f157eeacd46c900e9cfc684bdbc167 (diff) | |
| download | tip-23c57d1fa2b9530e38f7964b4e457fed5a7a0ae8.tar.gz | |
mseal: replace can_modify_mm_madv with a vma variant
Replace can_modify_mm_madv() with a single vma variant, and associated
checks in madvise.
While we're at it, also invert the order of checks in:
if (unlikely(is_ro_anon(vma) && !can_modify_vma(vma))
Checking if we can modify the vma itself (through vm_flags) is certainly
cheaper than is_ro_anon() due to arch_vma_access_permitted() looking at
e.g pkeys registers (with extra branches) in some architectures.
This patch allows for partial madvise success when finding a sealed VMA,
which historically has been allowed in Linux.
Link: https://lkml.kernel.org/r/20240817-mseal-depessimize-v3-5-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>
Diffstat (limited to 'mm/madvise.c')
| -rw-r--r-- | mm/madvise.c | 13 |
1 files changed, 3 insertions, 10 deletions
diff --git a/mm/madvise.c b/mm/madvise.c index 89089d84f8df87..4e64770be16c98 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -1031,6 +1031,9 @@ static int madvise_vma_behavior(struct vm_area_struct *vma, struct anon_vma_name *anon_name; unsigned long new_flags = vma->vm_flags; + if (unlikely(!can_modify_vma_madv(vma, behavior))) + return -EPERM; + switch (behavior) { case MADV_REMOVE: return madvise_remove(vma, prev, start, end); @@ -1448,15 +1451,6 @@ int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh start = untagged_addr_remote(mm, start); end = start + len; - /* - * Check if the address range is sealed for do_madvise(). - * can_modify_mm_madv assumes we have acquired the lock on MM. - */ - if (unlikely(!can_modify_mm_madv(mm, start, end, behavior))) { - error = -EPERM; - goto out; - } - blk_start_plug(&plug); switch (behavior) { case MADV_POPULATE_READ: @@ -1470,7 +1464,6 @@ int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh } blk_finish_plug(&plug); -out: if (write) mmap_write_unlock(mm); else |