Merge sys_clone()/sys_unshare() nsproxy and namespace handling

sys_clone() and sys_unshare() both makes copies of nsproxy and its associated
namespaces.  But they have different code paths.

This patch merges all the nsproxy and its associated namespace copy/clone
handling (as much as possible).  Posted on container list earlier for
feedback.

- Create a new nsproxy and its associated namespaces and pass it back to
  caller to attach it to right process.

- Changed all copy_*_ns() routines to return a new copy of namespace
  instead of attaching it to task->nsproxy.

- Moved the CAP_SYS_ADMIN checks out of copy_*_ns() routines.

- Removed unnessary !ns checks from copy_*_ns() and added BUG_ON()
  just incase.

- Get rid of all individual unshare_*_ns() routines and make use of
  copy_*_ns() instead.

[akpm@osdl.org: cleanups, warning fix]
[clg@fr.ibm.com: remove dup_namespaces() declaration]
[serue@us.ibm.com: fix CONFIG_IPC_NS=n, clone(CLONE_NEWIPC) retval]
[akpm@linux-foundation.org: fix build with CONFIG_SYSVIPC=n]
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Serge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: <containers@lists.osdl.org>
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 80 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index b7d169def942..fd211b9dddd4 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1516,26 +1516,6 @@ static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
 }
 
 /*
- * Unshare the mnt_namespace structure if it is being shared
- */
-static int unshare_mnt_namespace(unsigned long unshare_flags,
-                struct mnt_namespace **new_nsp, struct fs_struct *new_fs)
-{
-        struct mnt_namespace *ns = current->nsproxy->mnt_ns;
-
-        if ((unshare_flags & CLONE_NEWNS) && ns) {
-                if (!capable(CAP_SYS_ADMIN))
-                        return -EPERM;
-
-                *new_nsp = dup_mnt_ns(current, new_fs ? new_fs : current->fs);
-                if (!*new_nsp)
-                        return -ENOMEM;
-        }
-
-        return 0;
-}
-
-/*
  * Unsharing of sighand is not supported yet
  */
 static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp)
@@ -1593,16 +1573,6 @@ static int unshare_semundo(unsigned long unshare_flags, struct sem_undo_list **n
         return 0;
 }
 
-#ifndef CONFIG_IPC_NS
-static inline int unshare_ipcs(unsigned long flags, struct ipc_namespace **ns)
-{
-        if (flags & CLONE_NEWIPC)
-                return -EINVAL;
-
-        return 0;
-}
-#endif
-
 /*
  * unshare allows a process to 'unshare' part of the process
  * context which was originally shared using clone.  copy_*
@@ -1615,14 +1585,11 @@ asmlinkage long sys_unshare(unsigned long unshare_flags)
 {
         int err = 0;
         struct fs_struct *fs, *new_fs = NULL;
-        struct mnt_namespace *ns, *new_ns = NULL;
         struct sighand_struct *new_sigh = NULL;
         struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL;
         struct files_struct *fd, *new_fd = NULL;
         struct sem_undo_list *new_ulist = NULL;
         struct nsproxy *new_nsproxy = NULL, *old_nsproxy = NULL;
-        struct uts_namespace *uts, *new_uts = NULL;
-        struct ipc_namespace *ipc, *new_ipc = NULL;
 
         check_unshare_flags(&unshare_flags);
 
@@ -1637,36 +1604,24 @@ asmlinkage long sys_unshare(unsigned long unshare_flags)
                 goto bad_unshare_out;
         if ((err = unshare_fs(unshare_flags, &new_fs)))
                 goto bad_unshare_cleanup_thread;
-        if ((err = unshare_mnt_namespace(unshare_flags, &new_ns, new_fs)))
-                goto bad_unshare_cleanup_fs;
         if ((err = unshare_sighand(unshare_flags, &new_sigh)))
-                goto bad_unshare_cleanup_ns;
+                goto bad_unshare_cleanup_fs;
         if ((err = unshare_vm(unshare_flags, &new_mm)))
                 goto bad_unshare_cleanup_sigh;
         if ((err = unshare_fd(unshare_flags, &new_fd)))
                 goto bad_unshare_cleanup_vm;
         if ((err = unshare_semundo(unshare_flags, &new_ulist)))
                 goto bad_unshare_cleanup_fd;
-        if ((err = unshare_utsname(unshare_flags, &new_uts)))
+        if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
+                        new_fs)))
                 goto bad_unshare_cleanup_semundo;
-        if ((err = unshare_ipcs(unshare_flags, &new_ipc)))
-                goto bad_unshare_cleanup_uts;
-
-        if (new_ns || new_uts || new_ipc) {
-                old_nsproxy = current->nsproxy;
-                new_nsproxy = dup_namespaces(old_nsproxy);
-                if (!new_nsproxy) {
-                        err = -ENOMEM;
-                        goto bad_unshare_cleanup_ipc;
-                }
-        }
 
-        if (new_fs || new_ns || new_mm || new_fd || new_ulist ||
-                                new_uts || new_ipc) {
+        if (new_fs ||  new_mm || new_fd || new_ulist || new_nsproxy) {
 
                 task_lock(current);
 
                 if (new_nsproxy) {
+                        old_nsproxy = current->nsproxy;
                         current->nsproxy = new_nsproxy;
                         new_nsproxy = old_nsproxy;
                 }
@@ -1677,12 +1632,6 @@ asmlinkage long sys_unshare(unsigned long unshare_flags)
                         new_fs = fs;
                 }
 
-                if (new_ns) {
-                        ns = current->nsproxy->mnt_ns;
-                        current->nsproxy->mnt_ns = new_ns;
-                        new_ns = ns;
-                }
-
                 if (new_mm) {
                         mm = current->mm;
                         active_mm = current->active_mm;
@@ -1698,32 +1647,12 @@ asmlinkage long sys_unshare(unsigned long unshare_flags)
                         new_fd = fd;
                 }
 
-                if (new_uts) {
-                        uts = current->nsproxy->uts_ns;
-                        current->nsproxy->uts_ns = new_uts;
-                        new_uts = uts;
-                }
-
-                if (new_ipc) {
-                        ipc = current->nsproxy->ipc_ns;
-                        current->nsproxy->ipc_ns = new_ipc;
-                        new_ipc = ipc;
-                }
-
                 task_unlock(current);
         }
 
         if (new_nsproxy)
                 put_nsproxy(new_nsproxy);
 
-bad_unshare_cleanup_ipc:
-        if (new_ipc)
-                put_ipc_ns(new_ipc);
-
-bad_unshare_cleanup_uts:
-        if (new_uts)
-                put_uts_ns(new_uts);
-
 bad_unshare_cleanup_semundo:
 bad_unshare_cleanup_fd:
         if (new_fd)
@@ -1738,10 +1667,6 @@ bad_unshare_cleanup_sigh:
                 if (atomic_dec_and_test(&new_sigh->count))
                         kmem_cache_free(sighand_cachep, new_sigh);
 
-bad_unshare_cleanup_ns:
-        if (new_ns)
-                put_mnt_ns(new_ns);
-
 bad_unshare_cleanup_fs:
         if (new_fs)
                 put_fs_struct(new_fs);