diff options
author | Eric W. Biederman <ebiederm@xmission.com> | 2012-07-26 06:24:06 -0700 |
---|---|---|
committer | Eric W. Biederman <ebiederm@xmission.com> | 2012-11-20 04:18:13 -0800 |
commit | cde1975bc242f3e1072bde623ef378e547b73f91 (patch) | |
tree | 2c40083144c71d2aa2be39ed65f610570261f647 /kernel/user_namespace.c | |
parent | 4c44aaafa8108f584831850ab48a975e971db2de (diff) | |
download | linux-cde1975bc242f3e1072bde623ef378e547b73f91.tar.gz linux-cde1975bc242f3e1072bde623ef378e547b73f91.tar.bz2 linux-cde1975bc242f3e1072bde623ef378e547b73f91.zip |
userns: Implent proc namespace operations
This allows entering a user namespace, and the ability
to store a reference to a user namespace with a bind
mount.
Addition of missing userns_ns_put in userns_install
from Gao feng <gaofeng@cn.fujitsu.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'kernel/user_namespace.c')
-rw-r--r-- | kernel/user_namespace.c | 90 |
1 files changed, 73 insertions, 17 deletions
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 49096d559e08..a9460774e77d 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -9,6 +9,7 @@ #include <linux/nsproxy.h> #include <linux/slab.h> #include <linux/user_namespace.h> +#include <linux/proc_fs.h> #include <linux/highuid.h> #include <linux/cred.h> #include <linux/securebits.h> @@ -26,6 +27,24 @@ static struct kmem_cache *user_ns_cachep __read_mostly; static bool new_idmap_permitted(struct user_namespace *ns, int cap_setid, struct uid_gid_map *map); +static void set_cred_user_ns(struct cred *cred, struct user_namespace *user_ns) +{ + /* Start with the same capabilities as init but useless for doing + * anything as the capabilities are bound to the new user namespace. + */ + cred->securebits = SECUREBITS_DEFAULT; + cred->cap_inheritable = CAP_EMPTY_SET; + cred->cap_permitted = CAP_FULL_SET; + cred->cap_effective = CAP_FULL_SET; + cred->cap_bset = CAP_FULL_SET; +#ifdef CONFIG_KEYS + key_put(cred->request_key_auth); + cred->request_key_auth = NULL; +#endif + /* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */ + cred->user_ns = user_ns; +} + /* * Create a new user namespace, deriving the creator from the user in the * passed credentials, and replacing that user with the new root user for the @@ -53,27 +72,12 @@ int create_user_ns(struct cred *new) return -ENOMEM; kref_init(&ns->kref); + /* Leave the new->user_ns reference with the new user namespace. */ ns->parent = parent_ns; ns->owner = owner; ns->group = group; - /* Start with the same capabilities as init but useless for doing - * anything as the capabilities are bound to the new user namespace. - */ - new->securebits = SECUREBITS_DEFAULT; - new->cap_inheritable = CAP_EMPTY_SET; - new->cap_permitted = CAP_FULL_SET; - new->cap_effective = CAP_FULL_SET; - new->cap_bset = CAP_FULL_SET; -#ifdef CONFIG_KEYS - key_put(new->request_key_auth); - new->request_key_auth = NULL; -#endif - /* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */ - - /* Leave the new->user_ns reference with the new user namespace. */ - /* Leave the reference to our user_ns with the new cred. */ - new->user_ns = ns; + set_cred_user_ns(new, ns); return 0; } @@ -737,6 +741,58 @@ static bool new_idmap_permitted(struct user_namespace *ns, int cap_setid, return false; } +static void *userns_get(struct task_struct *task) +{ + struct user_namespace *user_ns; + + rcu_read_lock(); + user_ns = get_user_ns(__task_cred(task)->user_ns); + rcu_read_unlock(); + + return user_ns; +} + +static void userns_put(void *ns) +{ + put_user_ns(ns); +} + +static int userns_install(struct nsproxy *nsproxy, void *ns) +{ + struct user_namespace *user_ns = ns; + struct cred *cred; + + /* Don't allow gaining capabilities by reentering + * the same user namespace. + */ + if (user_ns == current_user_ns()) + return -EINVAL; + + /* Threaded many not enter a different user namespace */ + if (atomic_read(¤t->mm->mm_users) > 1) + return -EINVAL; + + if (!ns_capable(user_ns, CAP_SYS_ADMIN)) + return -EPERM; + + cred = prepare_creds(); + if (!cred) + return -ENOMEM; + + put_user_ns(cred->user_ns); + set_cred_user_ns(cred, get_user_ns(user_ns)); + + return commit_creds(cred); +} + +const struct proc_ns_operations userns_operations = { + .name = "user", + .type = CLONE_NEWUSER, + .get = userns_get, + .put = userns_put, + .install = userns_install, +}; + static __init int user_namespaces_init(void) { user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC); |