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Revert "UPSTREAM: mm/memfd: make F_SEAL_FUTURE_WRITE seal more robust"

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This reverts commit 2e0d7ea44a.

Change-Id: Id8ca9575c75db3eeb06b7aa7217a59c85e55d0ac
This commit is contained in:
Joel Fernandes 2019-01-16 09:42:37 -05:00
parent 9133e3486a
commit 3a49374afc
3 changed files with 23 additions and 22 deletions
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2
fs/hugetlbfs/inode.c
View File

@ -530,7 +530,7 @@ static long hugetlbfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
inode_lock(inode);
/* protected by i_mutex */
if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
if (info->seals & F_SEAL_WRITE) {
inode_unlock(inode);
return -EPERM;
}

19
mm/memfd.c
View File

@ -220,6 +220,25 @@ static int memfd_add_seals(struct file *file, unsigned int seals)
}
}
if ((seals & F_SEAL_FUTURE_WRITE) &&
!(*file_seals & F_SEAL_FUTURE_WRITE)) {
/*
* The FUTURE_WRITE seal also prevents growing and shrinking
* so we need them to be already set, or requested now.
*/
int test_seals = (seals | *file_seals) &
(F_SEAL_GROW | F_SEAL_SHRINK);
if (test_seals != (F_SEAL_GROW | F_SEAL_SHRINK)) {
error = -EINVAL;
goto unlock;
}
spin_lock(&file->f_lock);
file->f_mode &= ~(FMODE_WRITE | FMODE_PWRITE);
spin_unlock(&file->f_lock);
}
*file_seals |= seals;
error = 0;

24
mm/shmem.c
View File

@ -2169,23 +2169,6 @@ int shmem_lock(struct file *file, int lock, struct user_struct *user)
static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
{
struct shmem_inode_info *info = SHMEM_I(file_inode(file));
/*
* New PROT_READ and MAP_SHARED mmaps are not allowed when "future
* write" seal active.
*/
if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE) &&
(info->seals & F_SEAL_FUTURE_WRITE))
return -EPERM;
/*
* Since the F_SEAL_FUTURE_WRITE seals allow for a MAP_SHARED read-only
* mapping, take care to not allow mprotect to revert protections.
*/
if (info->seals & F_SEAL_FUTURE_WRITE)
vma->vm_flags &= ~(VM_MAYWRITE);
file_accessed(file);
vma->vm_ops = &shmem_vm_ops;
if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) &&
@ -2439,9 +2422,8 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
pgoff_t index = pos >> PAGE_SHIFT;
/* i_mutex is held by caller */
if (unlikely(info->seals & (F_SEAL_GROW |
F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))
if (unlikely(info->seals & (F_SEAL_WRITE | F_SEAL_GROW))) {
if (info->seals & F_SEAL_WRITE)
return -EPERM;
if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
return -EPERM;
@ -2704,7 +2686,7 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
/* protected by i_mutex */
if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
if (info->seals & F_SEAL_WRITE) {
error = -EPERM;
goto out;
}