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ffs_mount(): return early if namei() fails to lookup disk device

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With soft updates enabled, an INVARIANTS panic is hit in ffs_unmount().

The problem occurs in ffs_mount() when upgrading a mount from ro->rw.
During a mount update, the soft update code gets set up but doesn't get
cleaned up if namei() fails when looking up the disk device.

Avoid this scenario by looking up the disk device first and bail early
if the namei() lookup fails.

PR:             256511
MFC After:      2 weeks
Reviewed by:	mckusick, kib
Differential Revision:	https://reviews.freebsd.org/D30870
This commit is contained in:
Robert Wing 2022-03-07 10:18:03 -09:00
parent dd7a5bc1e6
commit 0455cc7104
1 changed files with 72 additions and 76 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

148
sys/ufs/ffs/ffs_vfsops.c
View File

@ -409,15 +409,84 @@ ffs_mount(struct mount *mp)
mp->mnt_kern_flag &= ~MNTK_FPLOOKUP;
mp->mnt_flag |= mntorflags;
MNT_IUNLOCK(mp);
/*
* If updating, check whether changing from read-only to
* read/write; if there is no device name, that's all we do.
* Must not call namei() while owning busy ref.
*/
if (mp->mnt_flag & MNT_UPDATE) {
if (mp->mnt_flag & MNT_UPDATE)
vfs_unbusy(mp);
/*
* Not an update, or updating the name: look up the name
* and verify that it refers to a sensible disk device.
*/
NDINIT(&ndp, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, fspec);
error = namei(&ndp);
if ((mp->mnt_flag & MNT_UPDATE) != 0) {
/*
* Unmount does not start if MNT_UPDATE is set. Mount
* update busies mp before setting MNT_UPDATE. We
* must be able to retain our busy ref successfully,
* without sleep.
*/
error1 = vfs_busy(mp, MBF_NOWAIT);
MPASS(error1 == 0);
}
if (error != 0)
return (error);
NDFREE(&ndp, NDF_ONLY_PNBUF);
if (!vn_isdisk_error(ndp.ni_vp, &error)) {
vput(ndp.ni_vp);
return (error);
}
/*
* If mount by non-root, then verify that user has necessary
* permissions on the device.
*/
accmode = VREAD;
if ((mp->mnt_flag & MNT_RDONLY) == 0)
accmode |= VWRITE;
error = VOP_ACCESS(ndp.ni_vp, accmode, td->td_ucred, td);
if (error)
error = priv_check(td, PRIV_VFS_MOUNT_PERM);
if (error) {
vput(ndp.ni_vp);
return (error);
}
/*
* New mount
*
* We need the name for the mount point (also used for
* "last mounted on") copied in. If an error occurs,
* the mount point is discarded by the upper level code.
* Note that vfs_mount_alloc() populates f_mntonname for us.
*/
if ((mp->mnt_flag & MNT_UPDATE) == 0) {
if ((error = ffs_mountfs(ndp.ni_vp, mp, td)) != 0) {
vrele(ndp.ni_vp);
return (error);
}
} else {
/*
* When updating, check whether changing from read-only to
* read/write; if there is no device name, that's all we do.
*/
ump = VFSTOUFS(mp);
fs = ump->um_fs;
odevvp = ump->um_odevvp;
devvp = ump->um_devvp;
/*
* If it's not the same vnode, or at least the same device
* then it's not correct.
*/
if (ndp.ni_vp->v_rdev != ump->um_odevvp->v_rdev)
error = EINVAL; /* needs translation */
vput(ndp.ni_vp);
if (error)
return (error);
if (fs->fs_ronly == 0 &&
vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0)) {
/*
@ -620,79 +689,6 @@ ffs_mount(struct mount *mp)
*/
if (mp->mnt_flag & MNT_SNAPSHOT)
return (ffs_snapshot(mp, fspec));
/*
* Must not call namei() while owning busy ref.
*/
vfs_unbusy(mp);
}
/*
* Not an update, or updating the name: look up the name
* and verify that it refers to a sensible disk device.
*/
NDINIT(&ndp, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, fspec);
error = namei(&ndp);
if ((mp->mnt_flag & MNT_UPDATE) != 0) {
/*
* Unmount does not start if MNT_UPDATE is set. Mount
* update busies mp before setting MNT_UPDATE. We
* must be able to retain our busy ref succesfully,
* without sleep.
*/
error1 = vfs_busy(mp, MBF_NOWAIT);
MPASS(error1 == 0);
}
if (error != 0)
return (error);
NDFREE(&ndp, NDF_ONLY_PNBUF);
devvp = ndp.ni_vp;
if (!vn_isdisk_error(devvp, &error)) {
vput(devvp);
return (error);
}
/*
* If mount by non-root, then verify that user has necessary
* permissions on the device.
*/
accmode = VREAD;
if ((mp->mnt_flag & MNT_RDONLY) == 0)
accmode |= VWRITE;
error = VOP_ACCESS(devvp, accmode, td->td_ucred, td);
if (error)
error = priv_check(td, PRIV_VFS_MOUNT_PERM);
if (error) {
vput(devvp);
return (error);
}
if (mp->mnt_flag & MNT_UPDATE) {
/*
* Update only
*
* If it's not the same vnode, or at least the same device
* then it's not correct.
*/
if (devvp->v_rdev != ump->um_devvp->v_rdev)
error = EINVAL; /* needs translation */
vput(devvp);
if (error)
return (error);
} else {
/*
* New mount
*
* We need the name for the mount point (also used for
* "last mounted on") copied in. If an error occurs,
* the mount point is discarded by the upper level code.
* Note that vfs_mount_alloc() populates f_mntonname for us.
*/
if ((error = ffs_mountfs(devvp, mp, td)) != 0) {
vrele(devvp);
return (error);
}
}
MNT_ILOCK(mp);