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authorLinus Torvalds <torvalds@linux-foundation.org>2014-08-09 17:10:41 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-09 17:10:41 -0700
commit77e40aae766ccbbbb0324cb92ab22e6e998375d7 (patch)
treefb4e8e840aaeeaac62249d7585249c4634886baa /kernel
parent96784de59fb35077c2bb33c39328992b836d87d3 (diff)
parent344470cac42e887e68cfb5bdfa6171baf27f1eb5 (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull namespace updates from Eric Biederman: "This is a bunch of small changes built against 3.16-rc6. The most significant change for users is the first patch which makes setns drmatically faster by removing unneded rcu handling. The next chunk of changes are so that "mount -o remount,.." will not allow the user namespace root to drop flags on a mount set by the system wide root. Aks this forces read-only mounts to stay read-only, no-dev mounts to stay no-dev, no-suid mounts to stay no-suid, no-exec mounts to stay no exec and it prevents unprivileged users from messing with a mounts atime settings. I have included my test case as the last patch in this series so people performing backports can verify this change works correctly. The next change fixes a bug in NFS that was discovered while auditing nsproxy users for the first optimization. Today you can oops the kernel by reading /proc/fs/nfsfs/{servers,volumes} if you are clever with pid namespaces. I rebased and fixed the build of the !CONFIG_NFS_FS case yesterday when a build bot caught my typo. Given that no one to my knowledge bases anything on my tree fixing the typo in place seems more responsible that requiring a typo-fix to be backported as well. The last change is a small semantic cleanup introducing /proc/thread-self and pointing /proc/mounts and /proc/net at it. This prevents several kinds of problemantic corner cases. It is a user-visible change so it has a minute chance of causing regressions so the change to /proc/mounts and /proc/net are individual one line commits that can be trivially reverted. Unfortunately I lost and could not find the email of the original reporter so he is not credited. From at least one perspective this change to /proc/net is a refgression fix to allow pthread /proc/net uses that were broken by the introduction of the network namespace" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: proc: Point /proc/mounts at /proc/thread-self/mounts instead of /proc/self/mounts proc: Point /proc/net at /proc/thread-self/net instead of /proc/self/net proc: Implement /proc/thread-self to point at the directory of the current thread proc: Have net show up under /proc/<tgid>/task/<tid> NFS: Fix /proc/fs/nfsfs/servers and /proc/fs/nfsfs/volumes mnt: Add tests for unprivileged remount cases that have found to be faulty mnt: Change the default remount atime from relatime to the existing value mnt: Correct permission checks in do_remount mnt: Move the test for MNT_LOCK_READONLY from change_mount_flags into do_remount mnt: Only change user settable mount flags in remount namespaces: Use task_lock and not rcu to protect nsproxy
Diffstat (limited to 'kernel')
-rw-r--r--kernel/nsproxy.c15
-rw-r--r--kernel/utsname.c6
2 files changed, 7 insertions, 14 deletions
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index 8e7811086b82..ef42d0ab3115 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -204,20 +204,13 @@ void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
might_sleep();
+ task_lock(p);
ns = p->nsproxy;
+ p->nsproxy = new;
+ task_unlock(p);
- rcu_assign_pointer(p->nsproxy, new);
-
- if (ns && atomic_dec_and_test(&ns->count)) {
- /*
- * wait for others to get what they want from this nsproxy.
- *
- * cannot release this nsproxy via the call_rcu() since
- * put_mnt_ns() will want to sleep
- */
- synchronize_rcu();
+ if (ns && atomic_dec_and_test(&ns->count))
free_nsproxy(ns);
- }
}
void exit_task_namespaces(struct task_struct *p)
diff --git a/kernel/utsname.c b/kernel/utsname.c
index fd393124e507..883aaaa7de8a 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -93,13 +93,13 @@ static void *utsns_get(struct task_struct *task)
struct uts_namespace *ns = NULL;
struct nsproxy *nsproxy;
- rcu_read_lock();
- nsproxy = task_nsproxy(task);
+ task_lock(task);
+ nsproxy = task->nsproxy;
if (nsproxy) {
ns = nsproxy->uts_ns;
get_uts_ns(ns);
}
- rcu_read_unlock();
+ task_unlock(task);
return ns;
}