userns: allow sethostname in a container

Changelog:
	Feb 23: let clone_uts_ns() handle setting uts->user_ns
		To do so we need to pass in the task_struct who'll
		get the utsname, so we can get its user_ns.
	Feb 23: As per Oleg's coment, just pass in tsk, instead of two
		of its members.

Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Daniel Lezcano <daniel.lezcano@free.fr>
Acked-by: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/utsname.h b/include/linux/utsname.h
index 2c3c0f543705164492c171d45d804f6528b74a15..4e5b0213fdc16adc61dbb4d46ee5e98030c9a1cc 100644 (file)
--- a/include/linux/utsname.h
+++ b/include/linux/utsname.h
@@ -54,7 +54,7 @@ static inline void get_uts_ns(struct uts_namespace *ns)
 }
 
 extern struct uts_namespace *copy_utsname(unsigned long flags,
-                                       struct uts_namespace *ns);
+                                         struct task_struct *tsk);
 extern void free_uts_ns(struct kref *kref);
 
 static inline void put_uts_ns(struct uts_namespace *ns)
@@ -71,12 +71,12 @@ static inline void put_uts_ns(struct uts_namespace *ns)
 }
 
 static inline struct uts_namespace *copy_utsname(unsigned long flags,
-                                       struct uts_namespace *ns)
+                                                struct task_struct *tsk)
 {
        if (flags & CLONE_NEWUTS)
                return ERR_PTR(-EINVAL);
 
-       return ns;
+       return tsk->nsproxy->uts_ns;
 }
 #endif
 

diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index 034dc2ed13acbf979fe91ec91adfa816ff571a2d..b97fc9d04ddfe0994898941c8d7020c0558daeff 100644 (file)
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -69,16 +69,11 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
                goto out_ns;
        }
 
-       new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns);
+       new_nsp->uts_ns = copy_utsname(flags, tsk);
        if (IS_ERR(new_nsp->uts_ns)) {
                err = PTR_ERR(new_nsp->uts_ns);
                goto out_uts;
        }
-       if (new_nsp->uts_ns != tsk->nsproxy->uts_ns) {
-               put_user_ns(new_nsp->uts_ns->user_ns);
-               new_nsp->uts_ns->user_ns = task_cred_xxx(tsk, user)->user_ns;
-               get_user_ns(new_nsp->uts_ns->user_ns);
-       }
 
        new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
        if (IS_ERR(new_nsp->ipc_ns)) {

diff --git a/kernel/sys.c b/kernel/sys.c
index 1ad48b3b9068ff7454d753c7e36e844ab507afd8..5761c53e19e3e7058e93ba01d404a384d3a1dc13 100644 (file)
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1181,7 +1181,7 @@ SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
        int errno;
        char tmp[__NEW_UTS_LEN];
 
-       if (!capable(CAP_SYS_ADMIN))
+       if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
                return -EPERM;
        if (len < 0 || len > __NEW_UTS_LEN)
                return -EINVAL;

diff --git a/kernel/utsname.c b/kernel/utsname.c
index a7b3a8d1ad24cebcd69982aa9d924542d02cb53a..44646179eabae8e8fd848174869f7d1782c90be8 100644 (file)
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -31,7 +31,8 @@ static struct uts_namespace *create_uts_ns(void)
  * @old_ns: namespace to clone
  * Return NULL on error (failure to kmalloc), new ns otherwise
  */
-static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
+static struct uts_namespace *clone_uts_ns(struct task_struct *tsk,
+                                         struct uts_namespace *old_ns)
 {
        struct uts_namespace *ns;
 
@@ -41,8 +42,7 @@ static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
 
        down_read(&uts_sem);
        memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
-       ns->user_ns = old_ns->user_ns;
-       get_user_ns(ns->user_ns);
+       ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns);
        up_read(&uts_sem);
        return ns;
 }
@@ -53,8 +53,10 @@ static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
  * utsname of this process won't be seen by parent, and vice
  * versa.
  */
-struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *old_ns)
+struct uts_namespace *copy_utsname(unsigned long flags,
+                                  struct task_struct *tsk)
 {
+       struct uts_namespace *old_ns = tsk->nsproxy->uts_ns;
        struct uts_namespace *new_ns;
 
        BUG_ON(!old_ns);
@@ -63,7 +65,7 @@ struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *ol
        if (!(flags & CLONE_NEWUTS))
                return old_ns;
 
-       new_ns = clone_uts_ns(old_ns);
+       new_ns = clone_uts_ns(tsk, old_ns);
 
        put_uts_ns(old_ns);
        return new_ns;