Commit dc617f29 authored by Darrick J. Wong's avatar Darrick J. Wong

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: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent 1638045c
......@@ -1978,6 +1978,9 @@ ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
if (bdev_read_only(I_BDEV(bd_inode)))
return -EPERM;
if (IS_SWAPFILE(bd_inode))
return -ETXTBSY;
if (!iov_iter_count(from))
return 0;
......
......@@ -3547,4 +3547,15 @@ static inline void simple_fill_fsxattr(struct fsxattr *fa, __u32 xflags)
fa->fsx_xflags = xflags;
}
/*
* Flush file data before changing attributes. Caller must hold any locks
* required to prevent further writes to this file until we're done setting
* flags.
*/
static inline int inode_drain_writes(struct inode *inode)
{
inode_dio_wait(inode);
return filemap_write_and_wait(inode->i_mapping);
}
#endif /* _LINUX_FS_H */
......@@ -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;
......
......@@ -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;
......
......@@ -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))
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
......
......@@ -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:
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment