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xfs: use setattr_copy to set vfs inode attributes

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Filipe Manana pointed out that XFS' behavior w.r.t. setuid/setgid
revocation isn't consistent with btrfs[1] or ext4.  Those two
filesystems use the VFS function setattr_copy to convey certain
attributes from struct iattr into the VFS inode structure.

Andrey Zhadchenko reported[2] that XFS uses the wrong user namespace to
decide if it should clear setgid and setuid on a file attribute update.
This is a second symptom of the problem that Filipe noticed.

XFS, on the other hand, open-codes setattr_copy in xfs_setattr_mode,
xfs_setattr_nonsize, and xfs_setattr_time.  Regrettably, setattr_copy is
/not/ a simple copy function; it contains additional logic to clear the
setgid bit when setting the mode, and XFS' version no longer matches.

The VFS implements its own setuid/setgid stripping logic, which
establishes consistent behavior.  It's a tad unfortunate that it's
scattered across notify_change, should_remove_suid, and setattr_copy but
XFS should really follow the Linux VFS.  Adapt XFS to use the VFS
functions and get rid of the old functions.

[1] https://lore.kernel.org/fstests/CAL3q7H47iNQ=Wmk83WcGB-KBJVOEtR9+qGczzCeXJ9Y2KCV25Q@mail.gmail.com/
[2] https://lore.kernel.org/linux-xfs/20220221182218.748084-1-andrey.zhadchenko@virtuozzo.com/

Fixes: 7fa294c899 ("userns: Allow chown and setgid preservation")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Darrick J. Wong 2022-03-08 10:51:16 -08:00
parent eba0549bc7
commit e014f37db1
2 changed files with 5 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

56
fs/xfs/xfs_iops.c
View File

@ -613,37 +613,6 @@ xfs_vn_getattr(
return 0;
}
static void
xfs_setattr_mode(
struct xfs_inode *ip,
struct iattr *iattr)
{
struct inode *inode = VFS_I(ip);
umode_t mode = iattr->ia_mode;
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
inode->i_mode &= S_IFMT;
inode->i_mode |= mode & ~S_IFMT;
}
void
xfs_setattr_time(
struct xfs_inode *ip,
struct iattr *iattr)
{
struct inode *inode = VFS_I(ip);
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
if (iattr->ia_valid & ATTR_ATIME)
inode->i_atime = iattr->ia_atime;
if (iattr->ia_valid & ATTR_CTIME)
inode->i_ctime = iattr->ia_ctime;
if (iattr->ia_valid & ATTR_MTIME)
inode->i_mtime = iattr->ia_mtime;
}
static int
xfs_vn_change_ok(
struct user_namespace *mnt_userns,
@ -742,16 +711,6 @@ xfs_setattr_nonsize(
gid = (mask & ATTR_GID) ? iattr->ia_gid : igid;
uid = (mask & ATTR_UID) ? iattr->ia_uid : iuid;
/*
* CAP_FSETID overrides the following restrictions:
*
* The set-user-ID and set-group-ID bits of a file will be
* cleared upon successful return from chown()
*/
if ((inode->i_mode & (S_ISUID|S_ISGID)) &&
!capable(CAP_FSETID))
inode->i_mode &= ~(S_ISUID|S_ISGID);
/*
* Change the ownerships and register quota modifications
* in the transaction.
@ -763,7 +722,6 @@ xfs_setattr_nonsize(
olddquot1 = xfs_qm_vop_chown(tp, ip,
&ip->i_udquot, udqp);
}
inode->i_uid = uid;
}
if (!gid_eq(igid, gid)) {
if (XFS_IS_GQUOTA_ON(mp)) {
@ -774,15 +732,10 @@ xfs_setattr_nonsize(
olddquot2 = xfs_qm_vop_chown(tp, ip,
&ip->i_gdquot, gdqp);
}
inode->i_gid = gid;
}
}
if (mask & ATTR_MODE)
xfs_setattr_mode(ip, iattr);
if (mask & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME))
xfs_setattr_time(ip, iattr);
setattr_copy(mnt_userns, inode, iattr);
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
XFS_STATS_INC(mp, xs_ig_attrchg);
@ -1006,11 +959,8 @@ xfs_setattr_size(
xfs_inode_clear_eofblocks_tag(ip);
}
if (iattr->ia_valid & ATTR_MODE)
xfs_setattr_mode(ip, iattr);
if (iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME))
xfs_setattr_time(ip, iattr);
ASSERT(!(iattr->ia_valid & (ATTR_UID | ATTR_GID)));
setattr_copy(mnt_userns, inode, iattr);
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
XFS_STATS_INC(mp, xs_ig_attrchg);

3
fs/xfs/xfs_pnfs.c
View File

@ -319,7 +319,8 @@ xfs_fs_commit_blocks(
xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
xfs_setattr_time(ip, iattr);
ASSERT(!(iattr->ia_valid & (ATTR_UID | ATTR_GID)));
setattr_copy(&init_user_ns, inode, iattr);
if (update_isize) {
i_size_write(inode, iattr->ia_size);
ip->i_disk_size = iattr->ia_size;