diff options
Diffstat (limited to 'fs/namespace.c')
| -rw-r--r-- | fs/namespace.c | 35 |
1 files changed, 31 insertions, 4 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 1a0b9e3089a2..3dabe49f7376 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2060,14 +2060,41 @@ static bool is_mnt_ns_file(struct dentry *dentry) dentry->d_fsdata == &mntns_operations; } -static struct mnt_namespace *to_mnt_ns(struct ns_common *ns) +struct ns_common *from_mnt_ns(struct mnt_namespace *mnt) { - return container_of(ns, struct mnt_namespace, ns); + return &mnt->ns; } -struct ns_common *from_mnt_ns(struct mnt_namespace *mnt) +struct mnt_namespace *__lookup_next_mnt_ns(struct mnt_namespace *mntns, bool previous) { - return &mnt->ns; + guard(read_lock)(&mnt_ns_tree_lock); + for (;;) { + struct rb_node *node; + + if (previous) + node = rb_prev(&mntns->mnt_ns_tree_node); + else + node = rb_next(&mntns->mnt_ns_tree_node); + if (!node) + return ERR_PTR(-ENOENT); + + mntns = node_to_mnt_ns(node); + node = &mntns->mnt_ns_tree_node; + + if (!ns_capable_noaudit(mntns->user_ns, CAP_SYS_ADMIN)) + continue; + + /* + * Holding mnt_ns_tree_lock prevents the mount namespace from + * being freed but it may well be on it's deathbed. We want an + * active reference, not just a passive one here as we're + * persisting the mount namespace. + */ + if (!refcount_inc_not_zero(&mntns->ns.count)) + continue; + + return mntns; + } } static bool mnt_ns_loop(struct dentry *dentry) |