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Groups > linux.kernel > #1659085
| From | "Eric W. Biederman" <ebiederm@xmission.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 26/26] pidns: Ensure zap_pid_ns_processes always terminates |
| Date | 2017-06-06 21:20 +0200 |
| Message-ID | <tPsbg-4vm-37@gated-at.bofh.it> (permalink) |
| References | <tPs1B-4ry-43@gated-at.bofh.it> <tPsbf-4vm-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
The function zap_pid_processes terminates when the number of pids used by processes in a pid namespace drops to just those pids used by the last thread of the dying thread. Don't allow an init process aka a child_reaper to call setpgid(0, some_other_processes_pid). That case is already broken today as it would result in a pid namespace that will hang when the thread group leader dies. Thankfully I have not received that bug report so it appears that no one cares and uses that case. Limiting setpgid ensures that the only two pids in the pid namespace on the init process that are worth worrying about are the pid and the tgid. The pgrp will now either match the tgid or it will be from outside the pid namespace. Likewise the sid will either match the tgid or be from outside the pid namespace. To make it clear what is being counted test if the task's tgid is the same as the the task's pid. In particular the code does not count the number of processes in a pid namespace, just the number of pids those processes use. A subtle but important distinction for understanding the code. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> --- kernel/pid_namespace.c | 2 +- kernel/sys.c | 3 ++- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index 74a5a7255b4d..bdda73768cc0 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -208,7 +208,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns) int nr; int rc; struct task_struct *task, *me = current; - int init_pids = thread_group_leader(me) ? 1 : 2; + int init_pids = task_pid(me) != task_tgid(me) ? 2 : 1; /* Don't allow any more processes into the pid namespace */ disable_pid_allocation(pid_ns); diff --git a/kernel/sys.c b/kernel/sys.c index 705f14b28134..775dea1e2e06 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -975,7 +975,8 @@ SYSCALL_DEFINE2(setpgid, pid_t, pid, pid_t, pgid) pgrp = find_vpid(pgid); g = pid_task(pgrp, PIDTYPE_PGID); - if (!g || task_session(g) != task_session(group_leader)) + if (!g || task_session(g) != task_session(group_leader) || + is_child_reaper(task_tgid(p))) goto out; } -- 2.10.1
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[PATCH 00/26] Fixing wait, exit, ptrace, exec, and CLONE_THREAD ebiederm@xmission.com (Eric W. Biederman) - 2017-06-06 21:10 +0200
[PATCH 01/26] alpha: Remove unused TASK_GROUP_LEADER "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 12/26] wait: Directly test for the two cases where wait_task_zombie is called "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 15/26] wait: Don't delay !ptrace_reparented leaders "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 13/26] wait: Remove unused delay_group_leader "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 17/26] exit: Rework the exit states for ptracees "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 20/26] wait: Don't pass the list to wait_consider_task "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 26/26] pidns: Ensure zap_pid_ns_processes always terminates "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 19/26] wait: Simpler code for clearing notask_error in wait_consider_task "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 24/26] signal: In ptrace_stop improve identical signal detection "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 09/26] signal: Don't allow sending SIGKILL or SIGSTOP to init "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 03/26] signal: Do not perform permission checks when sending pdeath_signal "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
Re: [PATCH 03/26] signal: Do not perform permission checks when sending pdeath_signal Linus Torvalds <torvalds@linux-foundation.org> - 2017-06-06 22:10 +0200
Re: [PATCH 03/26] signal: Do not perform permission checks when sending pdeath_signal ebiederm@xmission.com (Eric W. Biederman) - 2017-06-07 13:40 +0200
Re: [PATCH 03/26] signal: Do not perform permission checks when sending pdeath_signal Richard Weinberger <richard.weinberger@gmail.com> - 2017-06-06 23:50 +0200
[PATCH 07/26] pidns: Improve the error handling in alloc_pid "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 22/26] exit: Fix auto-wait of ptraced children "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 02/26] cgroup: Don't open code tasklist_empty() "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 04/26] signal: Make group_send_sig_info static "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 23/26] signal: Fix SIGCONT before group stop completes. "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 18/26] wait: Fix WSTOPPED on a ptraced child "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 10/26] ptrace: Simplify ptrace_detach & exit_ptrace "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 21/26] wait: Optmize waitpid "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 14/26] wait: Move changing of ptrace from wait_consider_task into wait_task_stopped "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 08/26] exit: Make the runqueue rcu safe "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
Re: [PATCH 08/26] exit: Make the runqueue rcu safe Oleg Nesterov <oleg@redhat.com> - 2017-06-07 15:20 +0200
[PATCH 06/26] rlimit: Remove unnecessary grab of tasklist_lock "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
Re: [PATCH 06/26] rlimit: Remove unnecessary grab of tasklist_lock Oleg Nesterov <oleg@redhat.com> - 2017-06-07 14:40 +0200
Re: [PATCH 06/26] rlimit: Remove unnecessary grab of tasklist_lock ebiederm@xmission.com (Eric W. Biederman) - 2017-06-07 16:20 +0200
[PATCH 16/26] exit: Fix reporting a ptraced !reparented leader has exited "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 11/26] wait: Properly implement __WCLONE handling in the presence of exec and ptrace "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 05/26] exit: Remove the pointless clearing of SIGPENDING in __exit_signal "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:20 +0200
[PATCH 25/26] signal: In ptrace_stop use CLD_TRAPPED in all ptrace signals "Eric W. Biederman" <ebiederm@xmission.com> - 2017-06-06 21:30 +0200
Re: [PATCH 00/26] Fixing wait, exit, ptrace, exec, and CLONE_THREAD Aleksa Sarai <asarai@suse.de> - 2017-06-06 21:50 +0200
Re: [PATCH 00/26] Fixing wait, exit, ptrace, exec, and CLONE_THREAD ebiederm@xmission.com (Eric W. Biederman) - 2017-06-07 13:50 +0200
Re: [PATCH 00/26] Fixing wait, exit, ptrace, exec, and CLONE_THREAD Aleksa Sarai <asarai@suse.de> - 2017-06-07 14:30 +0200
Re: [PATCH 00/26] Fixing wait, exit, ptrace, exec, and CLONE_THREAD Linus Torvalds <torvalds@linux-foundation.org> - 2017-06-06 22:10 +0200
Re: [PATCH 00/26] Fixing wait, exit, ptrace, exec, and CLONE_THREAD ebiederm@xmission.com (Eric W. Biederman) - 2017-06-07 18:10 +0200
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