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Subject[PATCH 03/10] 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>
---
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 2c3c0f5..4e5b021 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 034dc2e..b97fc9d 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 18da702..7a1bbad 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1177,7 +1177,7 @@ 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 a7b3a8d..4464617 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;
--
1.7.0.4


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