diff options
| author | Darrick J. Wong <darrick.wong@oracle.com> | 2019-08-20 16:55:16 +0200 |
|---|---|---|
| committer | Darrick J. Wong <darrick.wong@oracle.com> | 2019-08-20 16:55:16 +0200 |
| commit | dc617f29dbe5ef0c8ced65ce62c464af1daaab3d (patch) | |
| tree | 3596eb0d334f04f87088c735748bba8e66a71cad /mm | |
| parent | mm: set S_SWAPFILE on blockdev swap devices (diff) | |
| download | linux-dc617f29dbe5ef0c8ced65ce62c464af1daaab3d.tar.xz linux-dc617f29dbe5ef0c8ced65ce62c464af1daaab3d.zip | |
vfs: don't allow writes to swap files
Don't let userspace write to an active swap file because the kernel
effectively has a long term lease on the storage and things could get
seriously corrupted if we let this happen.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/filemap.c | 3 | ||||
| -rw-r--r-- | mm/memory.c | 4 | ||||
| -rw-r--r-- | mm/mmap.c | 8 | ||||
| -rw-r--r-- | mm/swapfile.c | 12 |
4 files changed, 24 insertions, 3 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index d0cf700bf201..40667c2f3383 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2988,6 +2988,9 @@ inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from) loff_t count; int ret; + if (IS_SWAPFILE(inode)) + return -ETXTBSY; + if (!iov_iter_count(from)) return 0; diff --git a/mm/memory.c b/mm/memory.c index e2bb51b6242e..b1dff75640b7 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2196,6 +2196,10 @@ static vm_fault_t do_page_mkwrite(struct vm_fault *vmf) vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; + if (vmf->vma->vm_file && + IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host)) + return VM_FAULT_SIGBUS; + ret = vmf->vma->vm_ops->page_mkwrite(vmf); /* Restore original flags so that caller is not surprised */ vmf->flags = old_flags; diff --git a/mm/mmap.c b/mm/mmap.c index 7e8c3e8ae75f..6bc21fca20bc 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1483,8 +1483,12 @@ unsigned long do_mmap(struct file *file, unsigned long addr, case MAP_SHARED_VALIDATE: if (flags & ~flags_mask) return -EOPNOTSUPP; - if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) - return -EACCES; + if (prot & PROT_WRITE) { + if (!(file->f_mode & FMODE_WRITE)) + return -EACCES; + if (IS_SWAPFILE(file->f_mapping->host)) + return -ETXTBSY; + } /* * Make sure we don't allow writing to an append-only diff --git a/mm/swapfile.c b/mm/swapfile.c index a53b7c49b40e..dab43523afdd 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -3275,6 +3275,17 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) if (error) goto bad_swap; + /* + * Flush any pending IO and dirty mappings before we start using this + * swap device. + */ + inode->i_flags |= S_SWAPFILE; + error = inode_drain_writes(inode); + if (error) { + inode->i_flags &= ~S_SWAPFILE; + goto bad_swap; + } + mutex_lock(&swapon_mutex); prio = -1; if (swap_flags & SWAP_FLAG_PREFER) @@ -3295,7 +3306,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) atomic_inc(&proc_poll_event); wake_up_interruptible(&proc_poll_wait); - inode->i_flags |= S_SWAPFILE; error = 0; goto out; bad_swap: |