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| author | Pedro Falcato <pedro.falcato@gmail.com> | 2024-08-17 02:18:32 +0200 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-09-04 06:15:41 +0200 |
| commit | 23c57d1fa2b9530e38f7964b4e457fed5a7a0ae8 (patch) | |
| tree | 18ea09d6de61f1054f67568a06878502faa98ba2 | |
| parent | mm/mremap: replace can_modify_mm with can_modify_vma (diff) | |
| download | linux-23c57d1fa2b9530e38f7964b4e457fed5a7a0ae8.tar.xz linux-23c57d1fa2b9530e38f7964b4e457fed5a7a0ae8.zip | |
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>
| -rw-r--r-- | mm/internal.h | 2 | ||||
| -rw-r--r-- | mm/madvise.c | 13 | ||||
| -rw-r--r-- | mm/mseal.c | 17 | ||||
| -rw-r--r-- | mm/vma.h | 7 |
4 files changed, 14 insertions, 25 deletions
diff --git a/mm/internal.h b/mm/internal.h index cbe4849f6e73..241cf46a19f5 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1361,8 +1361,6 @@ static inline int can_do_mseal(unsigned long flags) bool can_modify_mm(struct mm_struct *mm, unsigned long start, unsigned long end); -bool can_modify_mm_madv(struct mm_struct *mm, unsigned long start, - unsigned long end, int behavior); #else static inline int can_do_mseal(unsigned long flags) { diff --git a/mm/madvise.c b/mm/madvise.c index 89089d84f8df..4e64770be16c 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 diff --git a/mm/mseal.c b/mm/mseal.c index 2170e2139ca0..fdd1666344fa 100644 --- a/mm/mseal.c +++ b/mm/mseal.c @@ -75,24 +75,15 @@ bool can_modify_mm(struct mm_struct *mm, unsigned long start, unsigned long end) } /* - * Check if the vmas of a memory range are allowed to be modified by madvise. - * the memory ranger can have a gap (unallocated memory). - * return true, if it is allowed. + * Check if a vma is allowed to be modified by madvise. */ -bool can_modify_mm_madv(struct mm_struct *mm, unsigned long start, unsigned long end, - int behavior) +bool can_modify_vma_madv(struct vm_area_struct *vma, int behavior) { - struct vm_area_struct *vma; - - VMA_ITERATOR(vmi, mm, start); - if (!is_madv_discard(behavior)) return true; - /* going through each vma to check. */ - for_each_vma_range(vmi, vma, end) - if (unlikely(is_ro_anon(vma) && !can_modify_vma(vma))) - return false; + if (unlikely(!can_modify_vma(vma) && is_ro_anon(vma))) + return false; /* Allow by default. */ return true; @@ -380,6 +380,8 @@ static inline bool can_modify_vma(struct vm_area_struct *vma) return true; } +bool can_modify_vma_madv(struct vm_area_struct *vma, int behavior); + #else static inline bool can_modify_vma(struct vm_area_struct *vma) @@ -387,6 +389,11 @@ static inline bool can_modify_vma(struct vm_area_struct *vma) return true; } +static inline bool can_modify_vma_madv(struct vm_area_struct *vma, int behavior) +{ + return true; +} + #endif #endif /* __MM_VMA_H */ |