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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>
This commit is contained in:
Serge E. Hallyn 2011-03-23 16:43:18 -07:00 committed by Linus Torvalds
parent 3486740a4f
commit bb96a6f50b
4 changed files with 12 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/utsname.h
View File

@ -54,7 +54,7 @@ static inline void get_uts_ns(struct uts_namespace *ns)
} }
extern struct uts_namespace *copy_utsname(unsigned long flags, 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); extern void free_uts_ns(struct kref *kref);
static inline void put_uts_ns(struct uts_namespace *ns) 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, static inline struct uts_namespace *copy_utsname(unsigned long flags,
struct uts_namespace *ns) struct task_struct *tsk)
{ {
if (flags & CLONE_NEWUTS) if (flags & CLONE_NEWUTS)
return ERR_PTR(-EINVAL); return ERR_PTR(-EINVAL);
return ns; return tsk->nsproxy->uts_ns;
} }
#endif #endif

7
kernel/nsproxy.c
View File

@ -69,16 +69,11 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
goto out_ns; 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)) { if (IS_ERR(new_nsp->uts_ns)) {
err = PTR_ERR(new_nsp->uts_ns); err = PTR_ERR(new_nsp->uts_ns);
goto out_uts; 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); new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
if (IS_ERR(new_nsp->ipc_ns)) { if (IS_ERR(new_nsp->ipc_ns)) {

2
kernel/sys.c
View File

@ -1181,7 +1181,7 @@ SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
int errno; int errno;
char tmp[__NEW_UTS_LEN]; char tmp[__NEW_UTS_LEN];
if (!capable(CAP_SYS_ADMIN)) if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
return -EPERM; return -EPERM;
if (len < 0 || len > __NEW_UTS_LEN) if (len < 0 || len > __NEW_UTS_LEN)
return -EINVAL; return -EINVAL;

12
kernel/utsname.c
View File

@ -31,7 +31,8 @@ static struct uts_namespace *create_uts_ns(void)
* @old_ns: namespace to clone * @old_ns: namespace to clone
* Return NULL on error (failure to kmalloc), new ns otherwise * 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; struct uts_namespace *ns;
@ -41,8 +42,7 @@ static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
down_read(&uts_sem); down_read(&uts_sem);
memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
ns->user_ns = old_ns->user_ns; ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns);
get_user_ns(ns->user_ns);
up_read(&uts_sem); up_read(&uts_sem);
return ns; 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 * utsname of this process won't be seen by parent, and vice
* versa. * 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; struct uts_namespace *new_ns;
BUG_ON(!old_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)) if (!(flags & CLONE_NEWUTS))
return old_ns; return old_ns;
new_ns = clone_uts_ns(old_ns); new_ns = clone_uts_ns(tsk, old_ns);
put_uts_ns(old_ns); put_uts_ns(old_ns);
return new_ns; return new_ns;