Created attachment 925466 [details]
trigger Kerneloops from any user
Description of problem:
Kerneloops handlers can be called by any user by communicating directly with the journal unix socket and setting the analyzer as Kerneloops. When this analyzer is set then dmesg is called and dumped to the output dump directory. The dump file is given the permissions of the calling user, which allows any user to read dmesg.
The problem is that no appropriate checks or privilege dropping is done before calling dmesg.
As long as bug is not duplicate (change type), always when the script is ran from any user.
Steps to Reproduce:
1. Set dmesg_restrict
2. Run attached Python script
3. Navigate to dump directory
4. View dmesg
$ cat /proc/sys/kernel/dmesg_restrict
dmesg: read kernel buffer failed: Operation not permitted
$ cat /dev/kmsg
cat: /dev/kmsg: Operation not permitted
$ python kerneloops.py
$ stat /var/tmp/abrt/dumpit-2014-08-09-23\:02\:36-1/dmesg
Access: (0660/-rw-rw----) Uid: ( 1001/ test) Gid: ( 173/ abrt)
Don't dump dmesg if calling user is restricted.
Thank you for the report! I am going to get one of our kernel people to check this, whether it should be treated as a security flaw or just hardening.
Murray McAllister / Red Hat Product Security
(In reply to Murray McAllister from comment #1)
Murray, any update on this bug report?
Should ABRT stop saving dmesg in the problem directories? Or should ABRT make the problem data accessible to root only if /proc/sys/kernel/dmesg_restrict is 1?
I prefer the latter option.
Apologies for missing this and the long delay. From our kernel person:
"this could be treated more as a hardening issue than a security one. More so, it needs to be fixed on the abrtd side, as it provides the journal socket access to user applications to write log messages. without it, the reproducer does not work."
I have asked someone to provide guidance on the question.
I'm removing the security flag from this bug. Fedora should not have embargoed issues and this should be opened up so it can be fixed.
With all of the new abrt issues going on around and other 'information disclosure' ones coming out, I figured I should update this ticket so it's in the list.
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Still present in Fedora 21 at least.
gnome-abrt-1.2.0-1.fc22,abrt-2.6.0-1.fc22,libreport-2.6.0-1.fc22,satyr-0.18-1.fc22 has been submitted as an update for Fedora 22.
Upstream commit https://github.com/abrt/abrt/commit/45975f6b8d6940865b67f63b99a062b5ecbb217b fixes this bug.
Package gnome-abrt-1.2.0-1.fc22, abrt-2.6.0-1.fc22, libreport-2.6.0-1.fc22, satyr-0.18-1.fc22:
* should fix your issue,
* was pushed to the Fedora 22 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing gnome-abrt-1.2.0-1.fc22 abrt-2.6.0-1.fc22 libreport-2.6.0-1.fc22 satyr-0.18-1.fc22'
as soon as you are able to.
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gnome-abrt-1.2.0-1.fc22, abrt-2.6.0-1.fc22, libreport-2.6.0-1.fc22, satyr-0.18-1.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.