Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1659113
| From | "Eric W. Biederman" <ebiederm@xmission.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 11/26] wait: Properly implement __WCLONE handling in the presence of exec and ptrace |
| Date | 2017-06-06 21:20 +0200 |
| Message-ID | <tPsbj-4vm-97@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 |
Rewrite the condition for what contitues a clone child. AKA a child
that reports to it's parent using something other than SIGCHLD.
If the parent has called exec since the child has started that child
will alwasy report to it's parent with SIGCHLD.
If the parent is only ptracing the child the child will always
report to the parent with SIGCHLD.
This implements the documented semantics and subsumes the fix Oleg
made in 4.7 to make __WCLONE unnecessary when ptracing a child. It was
just a bug in the check for __WCLONE support that made that necessary
the ``semantic'' change necessary.
Around v2.3.23 notify_parent was fixed to send SIGCHLD if the parent
had exec'd. Fixing half a bug but wait was not fixed to see children
in that case.
Not handling either the ptrace or the parent exec case appears to
go all of the way back to 1.0.
Fixes: bf959931ddb8 ("wait/ptrace: assume __WALL if the child is traced")
Fixes: v1.0
Fixes: v2.3.23
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
kernel/exit.c | 27 +++++++++++----------------
1 file changed, 11 insertions(+), 16 deletions(-)
diff --git a/kernel/exit.c b/kernel/exit.c
index 625e57f1bb5c..306e526f4c5e 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -950,31 +950,26 @@ static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
task_pid_type(p, wo->wo_type) == wo->wo_pid;
}
-static int
-eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
+static int eligible_child(struct wait_opts *wo, struct task_struct *p)
{
if (!eligible_pid(wo, p))
return 0;
/*
- * Wait for all children (clone and not) if __WALL is set or
- * if it is traced by us.
+ * Wait for all children (clone and not) if __WALL is set.
*/
- if (ptrace || (wo->wo_flags & __WALL))
+ if (wo->wo_flags & __WALL)
return 1;
/*
- * Otherwise, wait for clone children *only* if __WCLONE is set;
- * otherwise, wait for non-clone children *only*.
- *
- * Note: a "clone" child here is one that reports to its parent
- * using a signal other than SIGCHLD, or a non-leader thread which
- * we can only see if it is traced by us.
+ * Otherwise wait for either children that report to their
+ * parent via SIGCHLD (when __WCLONE is not set) or use
+ * another signal (when __WCLONE is set).
*/
- if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
- return 0;
-
- return 1;
+ return (((p->exit_signal == SIGCHLD) ||
+ (p->parent_exec_id == p->real_parent->self_exec_id))
+ && thread_group_leader(p) && !ptrace_reparented(p)) ^
+ !!(wo->wo_flags & __WCLONE);
}
static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
@@ -1343,7 +1338,7 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace,
if (unlikely(exit_state == EXIT_DEAD))
return 0;
- ret = eligible_child(wo, ptrace, p);
+ ret = eligible_child(wo, p);
if (!ret)
return ret;
--
2.10.1
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[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
csiph-web