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-rw-r--r--fs/xfs/xfs_symlink.c512
1 files changed, 512 insertions, 0 deletions
diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c
new file mode 100644
index 000000000..8389f3ef8
--- /dev/null
+++ b/fs/xfs/xfs_symlink.c
@@ -0,0 +1,512 @@
+// 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 user_namespace *mnt_userns,
+ 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(mnt_userns, &init_user_ns),
+ mapped_fsgid(mnt_userns, &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(mnt_userns, 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);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-30 23:33:10 +0000