This bug may have regressed again in the 3.19 kernel. Does this issue
go away if you boot into the 3.18.0-8.9 kernel?
** Changed in: linux (Ubuntu Vivid)
Status: Fix Released => Confirmed
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https://bugs.launchpad.net/bugs/1390223
Title:
Apparmor related regression on access to unix sockets on a candidate
3.16 backport kernel
Status in linux package in Ubuntu:
Confirmed
Status in linux source package in Utopic:
Confirmed
Status in linux source package in Vivid:
Confirmed
Bug description:
I recently noticed a bunch of containers failing in a rather odd way
when running postfix.
The most visible example is when running mailq on an empty queue.
Without apparmor (unconfined container) I see that the queue is empty,
with apparmor, I get Permission denied.
That's all running as root so the permission denied looks a tiny bit
odd. Also, running the 3.13 kernel, I don't get any of that weirdness.
My guess is that it has to do with the work that went into the 3.16
kernel for socket mediation. In theory only systems that run the
utopic apparmor (which I DO NOT) should be seeing that kind of
behavior, but it looks like some code path isn't checking things
properly :)
== strace in unconfined container ==
chdir("/var/spool/postfix") = 0
rt_sigaction(SIGPIPE, {SIG_IGN, [PIPE], SA_RESTORER|SA_RESTART,
0x7f8963a62c30}, {SIG_IGN, [], 0}, 8) = 0
getuid() = 0
socket(PF_LOCAL, SOCK_STREAM, 0) = 4
fcntl(4, F_GETFL) = 0x2 (flags O_RDWR)
fcntl(4, F_SETFL, O_RDWR) = 0
connect(4, {sa_family=AF_LOCAL, sun_path="public/showq"}, 110) = 0
poll([{fd=4, events=POLLIN}], 1, 3600000) = 1 ([{fd=4,
revents=POLLIN|POLLHUP}])
read(4, "Mail queue is empty\n", 4096) = 20
poll([{fd=4, events=POLLIN}], 1, 3600000) = 1 ([{fd=4,
revents=POLLIN|POLLHUP}])
read(4, "", 4096) = 0
write(1, "Mail queue is empty\n", 20Mail queue is empty
) = 20
close(4) = 0
exit_group(0) = ?
+++ exited with 0 +++
== strace in confined container ==
chdir("/var/spool/postfix") = 0
rt_sigaction(SIGPIPE, {SIG_IGN, [PIPE], SA_RESTORER|SA_RESTART,
0x7ffe62de4c30}, {SIG_IGN, [], 0}, 8) = 0
getuid() = 0
socket(PF_LOCAL, SOCK_STREAM, 0) = 4
fcntl(4, F_GETFL) = 0x2 (flags O_RDWR)
fcntl(4, F_SETFL, O_RDWR) = 0
connect(4, {sa_family=AF_LOCAL, sun_path="public/showq"}, 110) = 0
poll([{fd=4, events=POLLIN}], 1, 3600000) = 1 ([{fd=4,
revents=POLLIN|POLLHUP}])
read(4, 0x7ffe65b35c00, 4096) = -1 EACCES (Permission denied)
close(4) = 0
write(2, "postqueue: warning: close: Permi"..., 45postqueue: warning: close:
Permission denied
) = 45
sendto(3, "<20>Nov 6 20:40:42 postfix/post"..., 78, MSG_NOSIGNAL, NULL, 0) =
78
exit_group(0) = ?
Kernel is a slightly outdated version of the kernel from the kernel team PPA:
Linux shell01 3.16.0-23-generic #31-Ubuntu SMP Thu Oct 23 20:13:35 UTC 2014
x86_64 x86_64 x86_64 GNU/Linux
If you think the latest build will improve this, I can test it, but
seeing how this is a production server, I can't just flip kernels
every 5 minutes (I'm running 3.16 to avoid a nasty btrfs bug on 3.13).
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