Relying on syscall record for information and useless key/value duplication
So I realized today that we have overlapping information in records and I don't like it. A great example would be the MAC_STATUS record and how you can get duplicate info. Looking at that following output.
type=MAC_STATUS msg=audit(1326314451.473:1018): enforcing=0 old_enforcing=1 auid=4166 ses=2
type=SYSCALL msg=audit(1326314451.473:1018): arch=c000003e syscall=1 success=yes exit=1 a0=3 a1=7fffc73e1200 a2=1 a3=0 items=0 ppid=3110 pid=21435 auid=4166 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts3 ses=2 comm="setenforce" exe="/usr/sbin/setenforce" subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null)
What you see is that the MAC_STATUS record tells us more than about the mac status. It also includes the auid and ses. Why only that info? Why not other info like the SELinux context? What really bothers me is that We already get that info (and a lot more info) in the SYSCALL record. I believe this is bogus. What I'd like to do is to create a new record called the 'TASK_INFO' record that will contain:
ppid pid auid uid gid euid suid fsuid egid sgid fsgid tty ses comm exe subj
And have this record be 'automagically' emitted any time any record is emitted. Thus we don't have information duplication and even if you have rules to exclude the SYSCALL record you still get all the info you ever needed for the MAC_STATUS record you wanted.
Does this make sense? Is there a reason not to do this? It makes the code smaller, faster, easier to maintainer, and MUCH easier to prove correct and complete. It logically separates the info that is from the task doing the action from the records which are supposed to report on individual actions.
Shouldn't MAC_STATUS be about the mac status? Shouldn't config change records be about the config that changed? Shouldn't the xfrm records be about XFRM? Obviously attributing these actions to a given task is important, but it isn't being put where it belongs.
Quoted 2 lines · Eric Paris
So I realized today that we have overlapping information in records and I don't like it.
You realized this just today?? :-)
Quoted 13 lines
A great example would be the
MAC_STATUSrecord and how you can get duplicate info. Looking at that following output.type=MAC_STATUS msg=audit(1326314451.473:1018): enforcing=0 old_enforcing=1 auid=4166 ses=2
type=SYSCALL msg=audit(1326314451.473:1018): arch=c000003e syscall=1 success=yes exit=1 a0=3 a1=7fffc73e1200 a2=1 a3=0 items=0 ppid=3110 pid=21435 auid=4166 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts3 ses=2 comm="setenforce" exe="/usr/sbin/setenforce" subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null)What you see is that the
MAC_STATUSrecord tells us more than about the mac status. It also includes the auid and ses. Why only that info? Why not other info like the SELinux context? What really bothers me is that We already get that info (and a lot more info) in the SYSCALL record. I believe this is bogus. What I'd like to do is to create a new record called the 'TASK_INFO' record that will contain:
Quoted 5 lines
ppid pid auid uid gid euid suid fsuid egid sgid fsgid tty ses comm exe subj
And have this record be 'automagically' emitted any time any record is emitted.
Any time any record is emitted? This doesn't include auxiliary records,
does it? So at most, one TASK_INFO record associated with any audit event, regardless of how many records that event generates? My concern is for cases like when we flush the IPsec SPD entries. That's one SYSCALL that can turn into 10's (or 100's) of MAC_IPSEC_EVENT records. Would I get just one TASK_INFO or one per MAC_IPSEC_EVENT record? We only need one since all of these records have the same event number anyway so they'd be identical.
Quoted 5 lines
Thus we don't have information duplication and even if you have rules to exclude the SYSCALL record you still get all the info you ever needed for the
MAC_STATUSrecord you wanted.Does this make sense?
I'm all for cleaning things up but I have a couple of questions.
Are you also planning to change the basic AVC message so it would require a TASK_INFO message?
What about audit records that aren't associated with syscalls, such as all the messages that originate in user space? Just looking at one of my systems, I see things like CRYPTO_KEY_USER, DAEMON_START, all the AUTH-related records, etc. They have some of the same stuff.
Quoted 1 line
Is there a reason not to do this?
Breaking legacy programs?
Will this break programs that are only looking at a specific record type? For example, the MAC_IPSEC_EVENT record also has an auid, ses, and subj. The information in that record could be all anyone ever wanted for monitoring the SPD activity, even though there is also a SYSCALL record with even more information. If they never looked at the SYSCALL record before, now they'll have to look at the TASK_INFO record?
Most importantly (to me), will it break the audit-test suite? We try to be fuzzy in the way we look for information but we do have tests that look for a SYSCALL record looking for subj, auid, success, name and obj fields, for example. Our test suite is smart enough to collect all the auxillary records (CWD, PATH, etc) so if the TASK_INFO is associated with the syscall and the field names are the same, things might just work. I'd want to be sure of that.
Quoted 10 lines
It makes the
code smaller, faster, easier to maintainer, and MUCH easier to prove correct and complete. It logically separates the info that is from the task doing the action from the records which are supposed to report on individual actions.Shouldn't
MAC_STATUSbe about the mac status? Shouldn't config change records be about the config that changed? Shouldn't the xfrm records be about XFRM? Obviously attributing these actions to a given task is important, but it isn't being put where it belongs.
Would have loved to see this about 6 years ago. :-)
-- ljk
Quoted 5 lines
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Quoted 2 lines · Eric Paris
So I realized today that we have overlapping information in records and I don't like it.
I have a real strong feeling that you did it. :-) I'm not searching the archives for proof...but I remember it went something like this...we needed a MAC event showing it changed. We needed some basic info. Then later we needed some more info and then someone just changed it to dump the syscall record. In many cases, this is bloat.
What is required is much less fields and I would like to keep the overall event size as small as possible. Do I need a MAC_STATUS event? Yes. Do I need to know the syscall? no.
Quoted 10 lines
A great example would be the
MAC_STATUSrecord and how you can get duplicate info. Looking at that following output.type=MAC_STATUS msg=audit(1326314451.473:1018): enforcing=0 old_enforcing=1 auid=4166 ses=2 type=SYSCALL msg=audit(1326314451.473:1018): arch=c000003e syscall=1 success=yes exit=1 a0=3 a1=7fffc73e1200 a2=1 a3=0 items=0 ppid=3110 pid=21435 auid=4166 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts3 ses=2 comm="setenforce" exe="/usr/sbin/setenforce" subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null)
Quoted 2 lines
What you see is that the
MAC_STATUSrecord tells us more than about the mac status. It also includes the auid and ses. Why only that info?
What is required is this:
Date and time of the event,
type of event,
subject identity (if applicable),
the outcome (success or failure) of the event
and additional data depending on the event, like what configuration item changed (with old and new values), what was accessed, etc.
We have additional requirements of being able to trace each event back to an actual login hence the session data. Then you also have to record enough information about the subject that its useful. This includes at a minimum auid, uid, pid, and selinux context.
Quoted 1 line
Why not other info like the SELinux context?
I think when we asked for that, you added a line of code to grab the whole syscall since that was the simplest thing to do. :-)
Quoted 6 lines
What really bothers me is that We already get that info (and a lot more info) in the SYSCALL record. I believe this is bogus. What I'd like to do is to create a new record called the '
TASK_INFO' record that will contain:ppid pid auid uid gid euid suid fsuid egid sgid fsgid tty ses comm exe subj
Probably too much info and too late. I have a feeling that a change like this now would cause more problems than its worth.
I want to aim the audit system such that it can meet the new basic robustness protection profile. Meeting it would also allow meeting any other PP that I know of. It will require reviewing all audit records to make sure they conform to the new requirements.
http://www.niap-ccevs.org/pp/PP_GPOSPP_V1.0/
I'd really like to avoid any massive changes in record format until that work begins in earnest later this year. I want to create some regression testing tools in the mean time so that as we move forward, we can stay backwards compatible. Imagine an aggregating server with several different Linux platforms being aggregated and still being able to use the current tools. It has to be done.
Please, let's not go down this rat hole just yet. I'd rather catch up on the known bugs in the audit system like
https://bugzilla.redhat.com/show_bug.cgi?id=742562
then around summer/late spring start working towards GPOSPP's requirements and possibly reformat some events as part of that work.
-Steve
Quoted 41 lines · Steve Grubb
Quoted 2 lines · Eric Paris
So I realized today that we have overlapping information in records and I don't like it.
I have a real strong feeling that you did it. :-) I'm not searching the archives for proof...but I remember it went something like this...we needed a MAC event showing it changed. We needed some basic info. Then later we needed some more info and then someone just changed it to dump the syscall record. In many cases, this is bloat.
What is required is much less fields and I would like to keep the overall event size as small as possible. Do I need a
MAC_STATUSevent? Yes. Do I need to know the syscall? no.Quoted 10 lines
A great example would be the
MAC_STATUSrecord and how you can get duplicate info. Looking at that following output.type=MAC_STATUS msg=audit(1326314451.473:1018): enforcing=0 old_enforcing=1 auid=4166 ses=2 type=SYSCALL msg=audit(1326314451.473:1018): arch=c000003e syscall=1 success=yes exit=1 a0=3 a1=7fffc73e1200 a2=1 a3=0 items=0 ppid=3110 pid=21435 auid=4166 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts3 ses=2 comm="setenforce" exe="/usr/sbin/setenforce" subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null)
Quoted 2 lines
What you see is that the
MAC_STATUSrecord tells us more than about the mac status. It also includes the auid and ses. Why only that info?What is required is this:
Date and time of the event, type of event, subject identity (if applicable), the outcome (success or failure) of the event and additional data depending on the event, like what configuration item changed (with old and new values), what was accessed, etc.We have additional requirements of being able to trace each event back to an actual login hence the session data. Then you also have to record enough information about the subject that its useful. This includes at a minimum auid, uid, pid, and selinux context.
Quoted 1 line
Why not other info like the SELinux context?
I think when we asked for that, you added a line of code to grab the whole syscall since that was the simplest thing to do. :-)
Quoted 6 lines
What really bothers me is that We already get that info (and a lot more info) in the SYSCALL record. I believe this is bogus. What I'd like to do is to create a new record called the '
TASK_INFO' record that will contain:ppid pid auid uid gid euid suid fsuid egid sgid fsgid tty ses comm exe subj
Quoted 7 lines
Probably too much info and too late. I have a feeling that a change like this now would cause more problems than its worth.
I want to aim the audit system such that it can meet the new basic robustness protection profile. Meeting it would also allow meeting any other PP that I know of. It will require reviewing all audit records to make sure they conform to the new requirements.
http://www.niap-ccevs.org/pp/PP_GPOSPP_V1.0/
I'd really like to avoid any massive changes in record format until that work begins in earnest later this year. I want to create some regression testing tools in the mean time so that as we move forward, we can stay backwards compatible.
Feel free to submit patches for any missing tests to [email protected].
Quoted 14 lines
Imagine an aggregating server with several different Linux platforms being aggregated and still being able to use the current tools. It has to be done.
Please, let's not go down this rat hole just yet. I'd rather catch up on the known bugs in the audit system like
https://bugzilla.redhat.com/show_bug.cgi?id=742562
then around summer/late spring start working towards GPOSPP's requirements and possibly reformat some events as part of that work.
-Steve
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Quoted 4 lines · Steve Grubb
Please, let's not go down this rat hole just yet. I'd rather catch up on the known bugs in the audit system like
We also have this bug:
https://www.redhat.com/archives/linux-audit/2011-December/msg00030.html
which really needs looking into more than reformatting the events.
-Steve