The patch titled
Subject: mm/mremap: replace can_modify_mm with can_modify_vma
has been added to the -mm mm-unstable branch. Its filename is
mm-mremap-replace-can_modify_mm-with-can_modify_vma.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mremap-replace-can_modify_mm-with-can_modify_vma.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Pedro Falcato <pedro.falcato@xxxxxxxxx>
Subject: mm/mremap: replace can_modify_mm with can_modify_vma
Date: Sat, 17 Aug 2024 01:18:31 +0100
Delegate all can_modify checks to the proper places. Unmap checks are
done in do_unmap (et al). The source VMA check is done purposefully
before unmapping, to keep the original mseal semantics.
Link: https://lkml.kernel.org/r/20240817-mseal-depessimize-v3-4-d8d2e037df30@xxxxxxxxx
Signed-off-by: Pedro Falcato <pedro.falcato@xxxxxxxxx>
Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Jeff Xu <jeffxu@xxxxxxxxxxxx>
Cc: Kees Cook <kees@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mremap.c | 32 ++++++--------------------------
1 file changed, 6 insertions(+), 26 deletions(-)
--- a/mm/mremap.c~mm-mremap-replace-can_modify_mm-with-can_modify_vma
+++ a/mm/mremap.c
@@ -902,19 +902,6 @@ static unsigned long mremap_to(unsigned
if ((mm->map_count + 2) >= sysctl_max_map_count - 3)
return -ENOMEM;
- /*
- * In mremap_to().
- * Move a VMA to another location, check if src addr is sealed.
- *
- * Place can_modify_mm here because mremap_to()
- * does its own checking for address range, and we only
- * check the sealing after passing those checks.
- *
- * can_modify_mm assumes we have acquired the lock on MM.
- */
- if (unlikely(!can_modify_mm(mm, addr, addr + old_len)))
- return -EPERM;
-
if (flags & MREMAP_FIXED) {
/*
* In mremap_to().
@@ -1052,6 +1039,12 @@ SYSCALL_DEFINE5(mremap, unsigned long, a
goto out;
}
+ /* Don't allow remapping vmas when they have already been sealed */
+ if (!can_modify_vma(vma)) {
+ ret = -EPERM;
+ goto out;
+ }
+
if (is_vm_hugetlb_page(vma)) {
struct hstate *h __maybe_unused = hstate_vma(vma);
@@ -1079,19 +1072,6 @@ SYSCALL_DEFINE5(mremap, unsigned long, a
goto out;
}
- /*
- * Below is shrink/expand case (not mremap_to())
- * Check if src address is sealed, if so, reject.
- * In other words, prevent shrinking or expanding a sealed VMA.
- *
- * Place can_modify_mm here so we can keep the logic related to
- * shrink/expand together.
- */
- if (unlikely(!can_modify_mm(mm, addr, addr + old_len))) {
- ret = -EPERM;
- goto out;
- }
-
/*
* Always allow a shrinking remap: that just unmaps
* the unnecessary pages..
_
Patches currently in -mm which might be from pedro.falcato@xxxxxxxxx are
selftests-mm-add-mseal-test-for-no-discard-madvise.patch
selftests-mm-add-mseal-test-for-no-discard-madvise-fix.patch
mm-move-can_modify_vma-to-mm-vmah.patch
mm-munmap-replace-can_modify_mm-with-can_modify_vma.patch
mm-mprotect-replace-can_modify_mm-with-can_modify_vma.patch
mm-mremap-replace-can_modify_mm-with-can_modify_vma.patch
mseal-replace-can_modify_mm_madv-with-a-vma-variant.patch
mm-remove-can_modify_mm.patch
selftests-mm-add-more-mseal-traversal-tests.patch
