linux/fs/xfs/xfs_symlink.c
Christian Brauner c14329d39f
fs: port fs{g,u}id helpers to mnt_idmap
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:30 +01:00

513 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2000-2006 Silicon Graphics, Inc.
* Copyright (c) 2012-2013 Red Hat, Inc.
* All rights reserved.
*/
#include "xfs.h"
#include "xfs_shared.h"
#include "xfs_fs.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_mount.h"
#include "xfs_dir2.h"
#include "xfs_inode.h"
#include "xfs_bmap.h"
#include "xfs_bmap_btree.h"
#include "xfs_quota.h"
#include "xfs_symlink.h"
#include "xfs_trans_space.h"
#include "xfs_trace.h"
#include "xfs_trans.h"
#include "xfs_ialloc.h"
#include "xfs_error.h"
/* ----- Kernel only functions below ----- */
int
xfs_readlink_bmap_ilocked(
struct xfs_inode *ip,
char *link)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_bmbt_irec mval[XFS_SYMLINK_MAPS];
struct xfs_buf *bp;
xfs_daddr_t d;
char *cur_chunk;
int pathlen = ip->i_disk_size;
int nmaps = XFS_SYMLINK_MAPS;
int byte_cnt;
int n;
int error = 0;
int fsblocks = 0;
int offset;
ASSERT(xfs_isilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
fsblocks = xfs_symlink_blocks(mp, pathlen);
error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
if (error)
goto out;
offset = 0;
for (n = 0; n < nmaps; n++) {
d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
error = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
&bp, &xfs_symlink_buf_ops);
if (error)
return error;
byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
if (pathlen < byte_cnt)
byte_cnt = pathlen;
cur_chunk = bp->b_addr;
if (xfs_has_crc(mp)) {
if (!xfs_symlink_hdr_ok(ip->i_ino, offset,
byte_cnt, bp)) {
error = -EFSCORRUPTED;
xfs_alert(mp,
"symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
offset, byte_cnt, ip->i_ino);
xfs_buf_relse(bp);
goto out;
}
cur_chunk += sizeof(struct xfs_dsymlink_hdr);
}
memcpy(link + offset, cur_chunk, byte_cnt);
pathlen -= byte_cnt;
offset += byte_cnt;
xfs_buf_relse(bp);
}
ASSERT(pathlen == 0);
link[ip->i_disk_size] = '\0';
error = 0;
out:
return error;
}
int
xfs_readlink(
struct xfs_inode *ip,
char *link)
{
struct xfs_mount *mp = ip->i_mount;
xfs_fsize_t pathlen;
int error = -EFSCORRUPTED;
trace_xfs_readlink(ip);
if (xfs_is_shutdown(mp))
return -EIO;
xfs_ilock(ip, XFS_ILOCK_SHARED);
pathlen = ip->i_disk_size;
if (!pathlen)
goto out;
if (pathlen < 0 || pathlen > XFS_SYMLINK_MAXLEN) {
xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
__func__, (unsigned long long) ip->i_ino,
(long long) pathlen);
ASSERT(0);
goto out;
}
if (ip->i_df.if_format == XFS_DINODE_FMT_LOCAL) {
/*
* The VFS crashes on a NULL pointer, so return -EFSCORRUPTED
* if if_data is junk.
*/
if (XFS_IS_CORRUPT(ip->i_mount, !ip->i_df.if_u1.if_data))
goto out;
memcpy(link, ip->i_df.if_u1.if_data, pathlen + 1);
error = 0;
} else {
error = xfs_readlink_bmap_ilocked(ip, link);
}
out:
xfs_iunlock(ip, XFS_ILOCK_SHARED);
return error;
}
int
xfs_symlink(
struct mnt_idmap *idmap,
struct xfs_inode *dp,
struct xfs_name *link_name,
const char *target_path,
umode_t mode,
struct xfs_inode **ipp)
{
struct xfs_mount *mp = dp->i_mount;
struct xfs_trans *tp = NULL;
struct xfs_inode *ip = NULL;
int error = 0;
int pathlen;
bool unlock_dp_on_error = false;
xfs_fileoff_t first_fsb;
xfs_filblks_t fs_blocks;
int nmaps;
struct xfs_bmbt_irec mval[XFS_SYMLINK_MAPS];
xfs_daddr_t d;
const char *cur_chunk;
int byte_cnt;
int n;
struct xfs_buf *bp;
prid_t prid;
struct xfs_dquot *udqp = NULL;
struct xfs_dquot *gdqp = NULL;
struct xfs_dquot *pdqp = NULL;
uint resblks;
xfs_ino_t ino;
*ipp = NULL;
trace_xfs_symlink(dp, link_name);
if (xfs_is_shutdown(mp))
return -EIO;
/*
* Check component lengths of the target path name.
*/
pathlen = strlen(target_path);
if (pathlen >= XFS_SYMLINK_MAXLEN) /* total string too long */
return -ENAMETOOLONG;
ASSERT(pathlen > 0);
prid = xfs_get_initial_prid(dp);
/*
* Make sure that we have allocated dquot(s) on disk.
*/
error = xfs_qm_vop_dqalloc(dp, mapped_fsuid(idmap, &init_user_ns),
mapped_fsgid(idmap, &init_user_ns), prid,
XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
&udqp, &gdqp, &pdqp);
if (error)
return error;
/*
* The symlink will fit into the inode data fork?
* There can't be any attributes so we get the whole variable part.
*/
if (pathlen <= XFS_LITINO(mp))
fs_blocks = 0;
else
fs_blocks = xfs_symlink_blocks(mp, pathlen);
resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
error = xfs_trans_alloc_icreate(mp, &M_RES(mp)->tr_symlink, udqp, gdqp,
pdqp, resblks, &tp);
if (error)
goto out_release_dquots;
xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
unlock_dp_on_error = true;
/*
* Check whether the directory allows new symlinks or not.
*/
if (dp->i_diflags & XFS_DIFLAG_NOSYMLINKS) {
error = -EPERM;
goto out_trans_cancel;
}
/*
* Allocate an inode for the symlink.
*/
error = xfs_dialloc(&tp, dp->i_ino, S_IFLNK, &ino);
if (!error)
error = xfs_init_new_inode(idmap, tp, dp, ino,
S_IFLNK | (mode & ~S_IFMT), 1, 0, prid,
false, &ip);
if (error)
goto out_trans_cancel;
/*
* Now we join the directory inode to the transaction. We do not do it
* earlier because xfs_dir_ialloc might commit the previous transaction
* (and release all the locks). An error from here on will result in
* the transaction cancel unlocking dp so don't do it explicitly in the
* error path.
*/
xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
unlock_dp_on_error = false;
/*
* Also attach the dquot(s) to it, if applicable.
*/
xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
resblks -= XFS_IALLOC_SPACE_RES(mp);
/*
* If the symlink will fit into the inode, write it inline.
*/
if (pathlen <= xfs_inode_data_fork_size(ip)) {
xfs_init_local_fork(ip, XFS_DATA_FORK, target_path, pathlen);
ip->i_disk_size = pathlen;
ip->i_df.if_format = XFS_DINODE_FMT_LOCAL;
xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
} else {
int offset;
first_fsb = 0;
nmaps = XFS_SYMLINK_MAPS;
error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
XFS_BMAPI_METADATA, resblks, mval, &nmaps);
if (error)
goto out_trans_cancel;
resblks -= fs_blocks;
ip->i_disk_size = pathlen;
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
cur_chunk = target_path;
offset = 0;
for (n = 0; n < nmaps; n++) {
char *buf;
d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
error = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
BTOBB(byte_cnt), 0, &bp);
if (error)
goto out_trans_cancel;
bp->b_ops = &xfs_symlink_buf_ops;
byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
byte_cnt = min(byte_cnt, pathlen);
buf = bp->b_addr;
buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
byte_cnt, bp);
memcpy(buf, cur_chunk, byte_cnt);
cur_chunk += byte_cnt;
pathlen -= byte_cnt;
offset += byte_cnt;
xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
(char *)bp->b_addr);
}
ASSERT(pathlen == 0);
}
i_size_write(VFS_I(ip), ip->i_disk_size);
/*
* Create the directory entry for the symlink.
*/
error = xfs_dir_createname(tp, dp, link_name, ip->i_ino, resblks);
if (error)
goto out_trans_cancel;
xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
/*
* If this is a synchronous mount, make sure that the
* symlink transaction goes to disk before returning to
* the user.
*/
if (xfs_has_wsync(mp) || xfs_has_dirsync(mp))
xfs_trans_set_sync(tp);
error = xfs_trans_commit(tp);
if (error)
goto out_release_inode;
xfs_qm_dqrele(udqp);
xfs_qm_dqrele(gdqp);
xfs_qm_dqrele(pdqp);
*ipp = ip;
return 0;
out_trans_cancel:
xfs_trans_cancel(tp);
out_release_inode:
/*
* Wait until after the current transaction is aborted to finish the
* setup of the inode and release the inode. This prevents recursive
* transactions and deadlocks from xfs_inactive.
*/
if (ip) {
xfs_finish_inode_setup(ip);
xfs_irele(ip);
}
out_release_dquots:
xfs_qm_dqrele(udqp);
xfs_qm_dqrele(gdqp);
xfs_qm_dqrele(pdqp);
if (unlock_dp_on_error)
xfs_iunlock(dp, XFS_ILOCK_EXCL);
return error;
}
/*
* Free a symlink that has blocks associated with it.
*
* Note: zero length symlinks are not allowed to exist. When we set the size to
* zero, also change it to a regular file so that it does not get written to
* disk as a zero length symlink. The inode is on the unlinked list already, so
* userspace cannot find this inode anymore, so this change is not user visible
* but allows us to catch corrupt zero-length symlinks in the verifiers.
*/
STATIC int
xfs_inactive_symlink_rmt(
struct xfs_inode *ip)
{
struct xfs_buf *bp;
int done;
int error;
int i;
xfs_mount_t *mp;
xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
int nmaps;
int size;
xfs_trans_t *tp;
mp = ip->i_mount;
ASSERT(!xfs_need_iread_extents(&ip->i_df));
/*
* We're freeing a symlink that has some
* blocks allocated to it. Free the
* blocks here. We know that we've got
* either 1 or 2 extents and that we can
* free them all in one bunmapi call.
*/
ASSERT(ip->i_df.if_nextents > 0 && ip->i_df.if_nextents <= 2);
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
if (error)
return error;
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, 0);
/*
* Lock the inode, fix the size, turn it into a regular file and join it
* to the transaction. Hold it so in the normal path, we still have it
* locked for the second transaction. In the error paths we need it
* held so the cancel won't rele it, see below.
*/
size = (int)ip->i_disk_size;
ip->i_disk_size = 0;
VFS_I(ip)->i_mode = (VFS_I(ip)->i_mode & ~S_IFMT) | S_IFREG;
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
/*
* Find the block(s) so we can inval and unmap them.
*/
done = 0;
nmaps = ARRAY_SIZE(mval);
error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
mval, &nmaps, 0);
if (error)
goto error_trans_cancel;
/*
* Invalidate the block(s). No validation is done.
*/
for (i = 0; i < nmaps; i++) {
error = xfs_trans_get_buf(tp, mp->m_ddev_targp,
XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0,
&bp);
if (error)
goto error_trans_cancel;
xfs_trans_binval(tp, bp);
}
/*
* Unmap the dead block(s) to the dfops.
*/
error = xfs_bunmapi(tp, ip, 0, size, 0, nmaps, &done);
if (error)
goto error_trans_cancel;
ASSERT(done);
/*
* Commit the transaction. This first logs the EFI and the inode, then
* rolls and commits the transaction that frees the extents.
*/
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
error = xfs_trans_commit(tp);
if (error) {
ASSERT(xfs_is_shutdown(mp));
goto error_unlock;
}
/*
* Remove the memory for extent descriptions (just bookkeeping).
*/
if (ip->i_df.if_bytes)
xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
ASSERT(ip->i_df.if_bytes == 0);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
return 0;
error_trans_cancel:
xfs_trans_cancel(tp);
error_unlock:
xfs_iunlock(ip, XFS_ILOCK_EXCL);
return error;
}
/*
* xfs_inactive_symlink - free a symlink
*/
int
xfs_inactive_symlink(
struct xfs_inode *ip)
{
struct xfs_mount *mp = ip->i_mount;
int pathlen;
trace_xfs_inactive_symlink(ip);
if (xfs_is_shutdown(mp))
return -EIO;
xfs_ilock(ip, XFS_ILOCK_EXCL);
pathlen = (int)ip->i_disk_size;
ASSERT(pathlen);
if (pathlen <= 0 || pathlen > XFS_SYMLINK_MAXLEN) {
xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
__func__, (unsigned long long)ip->i_ino, pathlen);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
ASSERT(0);
return -EFSCORRUPTED;
}
/*
* Inline fork state gets removed by xfs_difree() so we have nothing to
* do here in that case.
*/
if (ip->i_df.if_format == XFS_DINODE_FMT_LOCAL) {
xfs_iunlock(ip, XFS_ILOCK_EXCL);
return 0;
}
xfs_iunlock(ip, XFS_ILOCK_EXCL);
/* remove the remote symlink */
return xfs_inactive_symlink_rmt(ip);
}