diff options
Diffstat (limited to 'fs/namespace.c')
-rw-r--r-- | fs/namespace.c | 100 |
1 files changed, 85 insertions, 15 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 53f6dadcdab5..1f24024b8d84 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -781,6 +781,20 @@ static void attach_mnt(struct mount *mnt, list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); } +static void attach_shadowed(struct mount *mnt, + struct mount *parent, + struct mount *shadows) +{ + if (shadows) { + hlist_add_after_rcu(&shadows->mnt_hash, &mnt->mnt_hash); + list_add(&mnt->mnt_child, &shadows->mnt_child); + } else { + hlist_add_head_rcu(&mnt->mnt_hash, + m_hash(&parent->mnt, mnt->mnt_mountpoint)); + list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); + } +} + /* * vfsmount lock must be held for write */ @@ -799,12 +813,7 @@ static void commit_tree(struct mount *mnt, struct mount *shadows) list_splice(&head, n->list.prev); - if (shadows) - hlist_add_after_rcu(&shadows->mnt_hash, &mnt->mnt_hash); - else - hlist_add_head_rcu(&mnt->mnt_hash, - m_hash(&parent->mnt, mnt->mnt_mountpoint)); - list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); + attach_shadowed(mnt, parent, shadows); touch_mnt_namespace(n); } @@ -891,8 +900,21 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~(MNT_WRITE_HOLD|MNT_MARKED); /* Don't allow unprivileged users to change mount flags */ - if ((flag & CL_UNPRIVILEGED) && (mnt->mnt.mnt_flags & MNT_READONLY)) - mnt->mnt.mnt_flags |= MNT_LOCK_READONLY; + if (flag & CL_UNPRIVILEGED) { + mnt->mnt.mnt_flags |= MNT_LOCK_ATIME; + + if (mnt->mnt.mnt_flags & MNT_READONLY) + mnt->mnt.mnt_flags |= MNT_LOCK_READONLY; + + if (mnt->mnt.mnt_flags & MNT_NODEV) + mnt->mnt.mnt_flags |= MNT_LOCK_NODEV; + + if (mnt->mnt.mnt_flags & MNT_NOSUID) + mnt->mnt.mnt_flags |= MNT_LOCK_NOSUID; + + if (mnt->mnt.mnt_flags & MNT_NOEXEC) + mnt->mnt.mnt_flags |= MNT_LOCK_NOEXEC; + } /* Don't allow unprivileged users to reveal what is under a mount */ if ((flag & CL_UNPRIVILEGED) && list_empty(&old->mnt_expire)) @@ -1208,6 +1230,11 @@ static void namespace_unlock(void) head.first->pprev = &head.first; INIT_HLIST_HEAD(&unmounted); + /* undo decrements we'd done in umount_tree() */ + hlist_for_each_entry(mnt, &head, mnt_hash) + if (mnt->mnt_ex_mountpoint.mnt) + mntget(mnt->mnt_ex_mountpoint.mnt); + up_write(&namespace_sem); synchronize_rcu(); @@ -1244,6 +1271,9 @@ void umount_tree(struct mount *mnt, int how) hlist_add_head(&p->mnt_hash, &tmp_list); } + hlist_for_each_entry(p, &tmp_list, mnt_hash) + list_del_init(&p->mnt_child); + if (how) propagate_umount(&tmp_list); @@ -1254,9 +1284,9 @@ void umount_tree(struct mount *mnt, int how) p->mnt_ns = NULL; if (how < 2) p->mnt.mnt_flags |= MNT_SYNC_UMOUNT; - list_del_init(&p->mnt_child); if (mnt_has_parent(p)) { put_mountpoint(p->mnt_mp); + mnt_add_count(p->mnt_parent, -1); /* move the reference to mountpoint into ->mnt_ex_mountpoint */ p->mnt_ex_mountpoint.dentry = p->mnt_mountpoint; p->mnt_ex_mountpoint.mnt = &p->mnt_parent->mnt; @@ -1487,6 +1517,7 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, continue; for (s = r; s; s = next_mnt(s, r)) { + struct mount *t = NULL; if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(s)) { s = skip_mnt_tree(s); @@ -1508,7 +1539,14 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, goto out; lock_mount_hash(); list_add_tail(&q->mnt_list, &res->mnt_list); - attach_mnt(q, parent, p->mnt_mp); + mnt_set_mountpoint(parent, p->mnt_mp, q); + if (!list_empty(&parent->mnt_mounts)) { + t = list_last_entry(&parent->mnt_mounts, + struct mount, mnt_child); + if (t->mnt_mp != p->mnt_mp) + t = NULL; + } + attach_shadowed(q, parent, t); unlock_mount_hash(); } } @@ -1891,9 +1929,6 @@ static int change_mount_flags(struct vfsmount *mnt, int ms_flags) if (readonly_request == __mnt_is_readonly(mnt)) return 0; - if (mnt->mnt_flags & MNT_LOCK_READONLY) - return -EPERM; - if (readonly_request) error = mnt_make_readonly(real_mount(mnt)); else @@ -1919,6 +1954,33 @@ static int do_remount(struct path *path, int flags, int mnt_flags, if (path->dentry != path->mnt->mnt_root) return -EINVAL; + /* Don't allow changing of locked mnt flags. + * + * No locks need to be held here while testing the various + * MNT_LOCK flags because those flags can never be cleared + * once they are set. + */ + if ((mnt->mnt.mnt_flags & MNT_LOCK_READONLY) && + !(mnt_flags & MNT_READONLY)) { + return -EPERM; + } + if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) && + !(mnt_flags & MNT_NODEV)) { + return -EPERM; + } + if ((mnt->mnt.mnt_flags & MNT_LOCK_NOSUID) && + !(mnt_flags & MNT_NOSUID)) { + return -EPERM; + } + if ((mnt->mnt.mnt_flags & MNT_LOCK_NOEXEC) && + !(mnt_flags & MNT_NOEXEC)) { + return -EPERM; + } + if ((mnt->mnt.mnt_flags & MNT_LOCK_ATIME) && + ((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (mnt_flags & MNT_ATIME_MASK))) { + return -EPERM; + } + err = security_sb_remount(sb, data); if (err) return err; @@ -1932,7 +1994,7 @@ static int do_remount(struct path *path, int flags, int mnt_flags, err = do_remount_sb(sb, flags, data, 0); if (!err) { lock_mount_hash(); - mnt_flags |= mnt->mnt.mnt_flags & MNT_PROPAGATION_MASK; + mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK; mnt->mnt.mnt_flags = mnt_flags; touch_mnt_namespace(mnt->mnt_ns); unlock_mount_hash(); @@ -2117,7 +2179,7 @@ static int do_new_mount(struct path *path, const char *fstype, int flags, */ if (!(type->fs_flags & FS_USERNS_DEV_MOUNT)) { flags |= MS_NODEV; - mnt_flags |= MNT_NODEV; + mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV; } } @@ -2431,6 +2493,14 @@ long do_mount(const char *dev_name, const char *dir_name, if (flags & MS_RDONLY) mnt_flags |= MNT_READONLY; + /* The default atime for remount is preservation */ + if ((flags & MS_REMOUNT) && + ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME | + MS_STRICTATIME)) == 0)) { + mnt_flags &= ~MNT_ATIME_MASK; + mnt_flags |= path.mnt->mnt_flags & MNT_ATIME_MASK; + } + flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | MS_STRICTATIME); |