From bb96a6f50be27390dc959ff67d9ea0ea0cfbe177 Mon Sep 17 00:00:00 2001 From: "Serge E. Hallyn" Date: Wed, 23 Mar 2011 16:43:18 -0700 Subject: [PATCH] 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 Acked-by: "Eric W. Biederman" Acked-by: Daniel Lezcano Acked-by: David Howells Cc: James Morris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/utsname.h | 6 +++--- kernel/nsproxy.c | 7 +------ kernel/sys.c | 2 +- kernel/utsname.c | 12 +++++++----- 4 files changed, 12 insertions(+), 15 deletions(-) diff --git a/include/linux/utsname.h b/include/linux/utsname.h index 2c3c0f543705..4e5b0213fdc1 100644 --- 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 034dc2ed13ac..b97fc9d04ddf 100644 --- 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 1ad48b3b9068..5761c53e19e3 100644 --- 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 a7b3a8d1ad24..44646179eaba 100644 --- 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;