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remove process and jail directory machinations from dounmount

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The manipulations done by mountcheckdirs() are not that useful during
the unmount, they can bring about unexpected security consequences.

Thic change effectively reverts the change in r73241.

The change also allows to simplify the handling of rootvnode global
variable.

Discussed with:	mckusick, mjg, kib
Reviewed by:	trasz
MFC after:	1 month
Differential Revision: https://reviews.freebsd.org/D12366
This commit is contained in:
avg 2017-10-13 09:42:05 +00:00
parent bdcff5173b
commit 13558f906a
1 changed files with 5 additions and 28 deletions
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33
sys/kern/vfs_mount.c
View File

@ -1262,7 +1262,7 @@ dounmount_cleanup(struct mount *mp, struct vnode *coveredvp, int mntkflags)
int
dounmount(struct mount *mp, int flags, struct thread *td)
{
struct vnode *coveredvp, *fsrootvp;
struct vnode *coveredvp;
int error;
uint64_t async_flag;
int mnt_gen_r;
@ -1364,22 +1364,6 @@ dounmount(struct mount *mp, int flags, struct thread *td)
MNT_IUNLOCK(mp);
cache_purgevfs(mp, false); /* remove cache entries for this file sys */
vfs_deallocate_syncvnode(mp);
/*
* For forced unmounts, move process cdir/rdir refs on the fs root
* vnode to the covered vnode. For non-forced unmounts we want
* such references to cause an EBUSY error.
*/
if ((flags & MNT_FORCE) &&
VFS_ROOT(mp, LK_EXCLUSIVE, &fsrootvp) == 0) {
if (mp->mnt_vnodecovered != NULL &&
(mp->mnt_flag & MNT_IGNORE) == 0)
mountcheckdirs(fsrootvp, mp->mnt_vnodecovered);
if (fsrootvp == rootvnode) {
vrele(rootvnode);
rootvnode = NULL;
}
vput(fsrootvp);
}
if ((mp->mnt_flag & MNT_RDONLY) != 0 || (flags & MNT_FORCE) != 0 ||
(error = VFS_SYNC(mp, MNT_WAIT)) == 0)
error = VFS_UNMOUNT(mp, flags);
@ -1391,17 +1375,6 @@ dounmount(struct mount *mp, int flags, struct thread *td)
* it doesn't exist anymore.
*/
if (error && error != ENXIO) {
if ((flags & MNT_FORCE) &&
VFS_ROOT(mp, LK_EXCLUSIVE, &fsrootvp) == 0) {
if (mp->mnt_vnodecovered != NULL &&
(mp->mnt_flag & MNT_IGNORE) == 0)
mountcheckdirs(mp->mnt_vnodecovered, fsrootvp);
if (rootvnode == NULL) {
rootvnode = fsrootvp;
vref(rootvnode);
}
vput(fsrootvp);
}
MNT_ILOCK(mp);
mp->mnt_kern_flag &= ~MNTK_NOINSMNTQ;
if ((mp->mnt_flag & MNT_RDONLY) == 0) {
@ -1432,6 +1405,10 @@ dounmount(struct mount *mp, int flags, struct thread *td)
VOP_UNLOCK(coveredvp, 0);
}
vfs_event_signal(NULL, VQ_UNMOUNT, 0);
if (rootvnode != NULL && mp == rootvnode->v_mount) {
vrele(rootvnode);
rootvnode = NULL;
}
if (mp == rootdevmp)
rootdevmp = NULL;
vfs_mount_destroy(mp);