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Don't use d_path() for automount mount point for chroot'd process

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Chroot'd process fails to automount snapshots due to realpath(3)
failure in mount.zfs(8).

Construct a mount point path from sb of the ctldir inode and dirent
name, instead of from d_path(), so that chroot'd process doesn't get
affected by its view of fs.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Closes #8903
Closes #8966
This commit is contained in:
Tomohiro Kusumi 2019-07-03 00:25:23 +09:00 committed by Tony Hutter
parent 7d2489cfad
commit 093bb64461
1 changed files with 7 additions and 34 deletions
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41
module/zfs/zfs_ctldir.c
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@ -703,37 +703,6 @@ zfsctl_snapshot_name(zfsvfs_t *zfsvfs, const char *snap_name, int len,
return (0);
}
/*
* Returns full path in full_path: "/pool/dataset/.zfs/snapshot/snap_name/"
*/
static int
zfsctl_snapshot_path(struct path *path, int len, char *full_path)
{
char *path_buffer, *path_ptr;
int path_len, error = 0;
path_buffer = kmem_alloc(len, KM_SLEEP);
path_ptr = d_path(path, path_buffer, len);
if (IS_ERR(path_ptr)) {
error = -PTR_ERR(path_ptr);
goto out;
}
path_len = path_buffer + len - 1 - path_ptr;
if (path_len > len) {
error = SET_ERROR(EFAULT);
goto out;
}
memcpy(full_path, path_ptr, path_len);
full_path[path_len] = '\0';
out:
kmem_free(path_buffer, len);
return (error);
}
/*
* Returns full path in full_path: "/pool/dataset/.zfs/snapshot/snap_name/"
*/
@ -1077,9 +1046,13 @@ zfsctl_snapshot_mount(struct path *path, int flags)
if (error)
goto error;
error = zfsctl_snapshot_path(path, MAXPATHLEN, full_path);
if (error)
goto error;
/*
* Construct a mount point path from sb of the ctldir inode and dirent
* name, instead of from d_path(), so that chroot'd process doesn't fail
* on mount.zfs(8).
*/
snprintf(full_path, MAXPATHLEN, "%s/.zfs/snapshot/%s",
zfsvfs->z_vfs->vfs_mntpoint, dname(dentry));
/*
* Multiple concurrent automounts of a snapshot are never allowed.