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>
diff --git a/mm/vma.h b/mm/vma.h
index e979015..da31d0f 100644
--- a/mm/vma.h
+++ b/mm/vma.h
@@ -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 */
