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.
Signed-off-by: Pedro Falcato pedro.falcato@gmail.com --- mm/mremap.c | 32 ++++++-------------------------- 1 file changed, 6 insertions(+), 26 deletions(-)
diff --git a/mm/mremap.c b/mm/mremap.c index e7ae140fc640..24712f8dbb6b 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -902,19 +902,6 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, 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, addr, unsigned long, old_len, 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, addr, unsigned long, old_len, 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..