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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
This commit is contained in:
commit
77e40aae76
23 changed files with 537 additions and 97 deletions
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@ -204,20 +204,13 @@ void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
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might_sleep();
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task_lock(p);
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ns = p->nsproxy;
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p->nsproxy = new;
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task_unlock(p);
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rcu_assign_pointer(p->nsproxy, new);
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if (ns && atomic_dec_and_test(&ns->count)) {
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/*
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* wait for others to get what they want from this nsproxy.
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*
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* cannot release this nsproxy via the call_rcu() since
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* put_mnt_ns() will want to sleep
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*/
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synchronize_rcu();
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if (ns && atomic_dec_and_test(&ns->count))
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free_nsproxy(ns);
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}
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}
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void exit_task_namespaces(struct task_struct *p)
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@ -93,13 +93,13 @@ static void *utsns_get(struct task_struct *task)
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struct uts_namespace *ns = NULL;
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struct nsproxy *nsproxy;
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rcu_read_lock();
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nsproxy = task_nsproxy(task);
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task_lock(task);
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nsproxy = task->nsproxy;
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if (nsproxy) {
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ns = nsproxy->uts_ns;
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get_uts_ns(ns);
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}
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rcu_read_unlock();
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task_unlock(task);
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return ns;
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}
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