mntns: Add a limit on the number of mount namespaces.
v2: Fixed the very obvious lack of setting ucounts on struct mnt_ns reported by Andrei Vagin, and the kbuild test report. Reported-by: Andrei Vagin <avagin@openvz.org> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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@ -10,6 +10,7 @@ struct mnt_namespace {
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struct mount * root;
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struct mount * root;
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struct list_head list;
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struct list_head list;
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struct user_namespace *user_ns;
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struct user_namespace *user_ns;
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struct ucounts *ucounts;
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u64 seq; /* Sequence number to prevent loops */
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u64 seq; /* Sequence number to prevent loops */
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wait_queue_head_t poll;
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wait_queue_head_t poll;
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u64 event;
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u64 event;
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@ -2719,9 +2719,20 @@ dput_out:
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return retval;
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return retval;
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}
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}
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static struct ucounts *inc_mnt_namespaces(struct user_namespace *ns)
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{
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return inc_ucount(ns, current_euid(), UCOUNT_MNT_NAMESPACES);
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}
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static void dec_mnt_namespaces(struct ucounts *ucounts)
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{
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dec_ucount(ucounts, UCOUNT_MNT_NAMESPACES);
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}
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static void free_mnt_ns(struct mnt_namespace *ns)
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static void free_mnt_ns(struct mnt_namespace *ns)
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{
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{
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ns_free_inum(&ns->ns);
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ns_free_inum(&ns->ns);
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dec_mnt_namespaces(ns->ucounts);
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put_user_ns(ns->user_ns);
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put_user_ns(ns->user_ns);
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kfree(ns);
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kfree(ns);
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}
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}
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@ -2738,14 +2749,22 @@ static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1);
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static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns)
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static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns)
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{
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{
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struct mnt_namespace *new_ns;
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struct mnt_namespace *new_ns;
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struct ucounts *ucounts;
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int ret;
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int ret;
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ucounts = inc_mnt_namespaces(user_ns);
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if (!ucounts)
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return ERR_PTR(-ENFILE);
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new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
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new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
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if (!new_ns)
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if (!new_ns) {
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dec_mnt_namespaces(ucounts);
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return ERR_PTR(-ENOMEM);
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return ERR_PTR(-ENOMEM);
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}
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ret = ns_alloc_inum(&new_ns->ns);
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ret = ns_alloc_inum(&new_ns->ns);
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if (ret) {
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if (ret) {
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kfree(new_ns);
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kfree(new_ns);
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dec_mnt_namespaces(ucounts);
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return ERR_PTR(ret);
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return ERR_PTR(ret);
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}
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}
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new_ns->ns.ops = &mntns_operations;
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new_ns->ns.ops = &mntns_operations;
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@ -2756,6 +2775,7 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns)
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init_waitqueue_head(&new_ns->poll);
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init_waitqueue_head(&new_ns->poll);
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new_ns->event = 0;
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new_ns->event = 0;
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new_ns->user_ns = get_user_ns(user_ns);
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new_ns->user_ns = get_user_ns(user_ns);
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new_ns->ucounts = ucounts;
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return new_ns;
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return new_ns;
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}
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}
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@ -30,6 +30,7 @@ enum ucount_type {
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UCOUNT_UTS_NAMESPACES,
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UCOUNT_UTS_NAMESPACES,
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UCOUNT_IPC_NAMESPACES,
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UCOUNT_IPC_NAMESPACES,
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UCOUNT_NET_NAMESPACES,
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UCOUNT_NET_NAMESPACES,
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UCOUNT_MNT_NAMESPACES,
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UCOUNT_CGROUP_NAMESPACES,
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UCOUNT_CGROUP_NAMESPACES,
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UCOUNT_COUNTS,
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UCOUNT_COUNTS,
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};
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};
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@ -72,6 +72,7 @@ static struct ctl_table user_table[] = {
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UCOUNT_ENTRY("max_uts_namespaces"),
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UCOUNT_ENTRY("max_uts_namespaces"),
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UCOUNT_ENTRY("max_ipc_namespaces"),
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UCOUNT_ENTRY("max_ipc_namespaces"),
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UCOUNT_ENTRY("max_net_namespaces"),
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UCOUNT_ENTRY("max_net_namespaces"),
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UCOUNT_ENTRY("max_mnt_namespaces"),
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UCOUNT_ENTRY("max_cgroup_namespaces"),
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UCOUNT_ENTRY("max_cgroup_namespaces"),
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{ }
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{ }
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};
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};
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