diff options
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/namespace.c | 84 |
1 files changed, 43 insertions, 41 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 00762f9a736a..0e342e2ade83 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -82,6 +82,7 @@ struct mount_kattr { unsigned int lookup_flags; bool recurse; struct user_namespace *mnt_userns; + struct mount *revert; }; /* /sys/fs */ @@ -4011,46 +4012,34 @@ static inline bool mnt_allow_writers(const struct mount_kattr *kattr, (mnt->mnt.mnt_flags & MNT_READONLY); } -static struct mount *mount_setattr_prepare(struct mount_kattr *kattr, - struct mount *mnt, int *err) +static int mount_setattr_prepare(struct mount_kattr *kattr, struct mount *mnt) { - struct mount *m = mnt, *last = NULL; - - if (!is_mounted(&m->mnt)) { - *err = -EINVAL; - goto out; - } - - if (!(mnt_has_parent(m) ? check_mnt(m) : is_anon_ns(m->mnt_ns))) { - *err = -EINVAL; - goto out; - } + struct mount *m = mnt; do { + int err = -EPERM; unsigned int flags; - flags = recalc_flags(kattr, m); - if (!can_change_locked_flags(m, flags)) { - *err = -EPERM; - goto out; - } + kattr->revert = m; - *err = can_idmap_mount(kattr, m); - if (*err) - goto out; + flags = recalc_flags(kattr, m); + if (!can_change_locked_flags(m, flags)) + return err; - last = m; + err = can_idmap_mount(kattr, m); + if (err) + return err; if (mnt_allow_writers(kattr, m)) continue; - *err = mnt_hold_writers(m); - if (*err) - goto out; + err = mnt_hold_writers(m); + if (err) + return err; } while (kattr->recurse && (m = next_mnt(m, mnt))); -out: - return last; + kattr->revert = NULL; + return 0; } static void do_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt) @@ -4078,14 +4067,12 @@ static void do_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt) put_user_ns(old_mnt_userns); } -static void mount_setattr_commit(struct mount_kattr *kattr, - struct mount *mnt, struct mount *last, - int err) +static void mount_setattr_finish(struct mount_kattr *kattr, struct mount *mnt) { struct mount *m = mnt; do { - if (!err) { + if (!kattr->revert) { unsigned int flags; do_idmap_mount(kattr, m); @@ -4097,24 +4084,24 @@ static void mount_setattr_commit(struct mount_kattr *kattr, if (m->mnt.mnt_flags & MNT_WRITE_HOLD) mnt_unhold_writers(m); - if (!err && kattr->propagation) + if (!kattr->revert && kattr->propagation) change_mnt_propagation(m, kattr->propagation); /* * On failure, only cleanup until we found the first mount * we failed to handle. */ - if (err && m == last) - break; + if (kattr->revert == m) + return; } while (kattr->recurse && (m = next_mnt(m, mnt))); - if (!err) + if (!kattr->revert) touch_mnt_namespace(mnt->mnt_ns); } static int do_mount_setattr(struct path *path, struct mount_kattr *kattr) { - struct mount *mnt = real_mount(path->mnt), *last = NULL; + struct mount *mnt = real_mount(path->mnt); int err = 0; if (path->dentry != mnt->mnt.mnt_root) @@ -4135,16 +4122,31 @@ static int do_mount_setattr(struct path *path, struct mount_kattr *kattr) } } + err = -EINVAL; lock_mount_hash(); + /* Ensure that this isn't anything purely vfs internal. */ + if (!is_mounted(&mnt->mnt)) + goto out; + /* - * Get the mount tree in a shape where we can change mount - * properties without failure. + * If this is an attached mount make sure it's located in the callers + * mount namespace. If it's not don't let the caller interact with it. + * If this is a detached mount make sure it has an anonymous mount + * namespace attached to it, i.e. we've created it via OPEN_TREE_CLONE. */ - last = mount_setattr_prepare(kattr, mnt, &err); - if (last) /* Commit all changes or revert to the old state. */ - mount_setattr_commit(kattr, mnt, last, err); + if (!(mnt_has_parent(mnt) ? check_mnt(mnt) : is_anon_ns(mnt->mnt_ns))) + goto out; + /* + * First, we get the mount tree in a shape where we can change mount + * properties without failure. If we succeeded to do so we commit all + * changes and if we failed we clean up. + */ + err = mount_setattr_prepare(kattr, mnt); + mount_setattr_finish(kattr, mnt); + +out: unlock_mount_hash(); if (kattr->propagation) { |