diff options
Diffstat (limited to 'fs/userfaultfd.c')
| -rw-r--r-- | fs/userfaultfd.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 9d20f75c1209..85877c5da0df 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -805,6 +805,18 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, goto out_unlock; /* + * UFFDIO_COPY will fill file holes even without + * PROT_WRITE. This check enforces that if this is a + * MAP_SHARED, the process has write permission to the backing + * file. If VM_MAYWRITE is set it also enforces that on a + * MAP_SHARED vma: there is no F_WRITE_SEAL and no further + * F_WRITE_SEAL can be taken until the vma is destroyed. + */ + ret = -EPERM; + if (unlikely(!(cur->vm_flags & VM_MAYWRITE))) + goto out_unlock; + + /* * Check that this vma isn't already owned by a * different userfaultfd. We can't allow more than one * userfaultfd to own a single vma simultaneously or we @@ -829,6 +841,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, BUG_ON(vma->vm_ops); BUG_ON(vma->vm_userfaultfd_ctx.ctx && vma->vm_userfaultfd_ctx.ctx != ctx); + WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); /* * Nothing to do: this vma is already registered into this @@ -970,6 +983,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, cond_resched(); BUG_ON(vma->vm_ops); + WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); /* * Nothing to do: this vma is already registered into this |