Question regarding audit message interpretation

Kangkook Jee aixer77 at gmail.com
Wed Jan 14 15:26:32 UTC 2015


Dear Richard

Thanks a lot for your prompt reply. 
According to your email and patches that you provided, CASE 2 is regarded as a clear error case. 

Then, How about CASE 1? Is this an error case or an intended behavior? 
If it is an error case, I assume we need to use the last item (in this case 'item=1’) for the open path. 
If not, what is the reason to have two items and what does each stand for?

Thanks again for your help in advance.

/Kangkook


> On Jan 14, 2015, at 9:30 AM, Richard Guy Briggs <rgb at redhat.com> wrote:
> 
> On 15/01/14, Kangkook Jee wrote:
>> Hi, all
> 
> Hi Kangkook,
> 
>> I have a question regarding how to interpret the audit message that we got for
>> an open system call. In most cases, we observe a single item (path) information
>> followed by 'syscall' and 'cwd' messages. However, in some cases, we see 2 or 3
>> items (paths) followed by 'syscall' and 'cwd' messages like following cases.
>> 
>> CASE 1:
>> 
>> Jan 14 11:00:01 hostname kernel: [4980285.399982] type=1300 audit(1421233201.056:893730395): arch=c000003e syscall=2 success=yes exit=5 a0=7ffff4ae5830 a1=c2 a2=180 a3=2233546f14d99 items=2 ppid=983 pid=5723 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 ses=4294967295 tty=(none) comm="cron" exe="/usr/sbin/cron" key=(null)
>> Jan 14 11:00:01 hostname kernel: [4980285.399985] type=1307 audit(1421233201.056:893730395):  cwd="/var/spool/cron"
>> Jan 14 11:00:01 hostname kernel: [4980285.399988] type=1302 audit(1421233201.056:893730395): item=0 name="/tmp/" inode=40961 dev=ca:01 mode=041777 ouid=0 ogid=0 rdev=00:00
>> Jan 14 11:00:01 hostname kernel: [4980285.399990] type=1302 audit(1421233201.056:893730395): item=1 name="/tmp/tmpfS9woiP" inode=30733 dev=ca:01 mode=0100600 ouid=0 ogid=0 rdev=00:00
>> 
>> CASE 2:
>> 
>> Jan 14 11:19:37 hostname kernel: [4981461.529450] type=1300 audit(1421234377.184:894228556): arch=c000003e syscall=2 success=yes exit=5 a0=fa9700 a1=441 a2=1b6 a3=0 items=3 ppid=5727 pid=5728 auid=4294967295 uid=1000 gid=1000 euid=1000 suid=1000 fsuid=1000 egid=1000 sgid=1000 fsgid=1000 ses=4294967295 tty=(none) comm="Run" exe="/usr/bin/perl" key=(null)
>> Jan 14 11:19:37 hostname kernel: [4981461.529454] type=1307 audit(1421234377.184:894228556):  cwd="/home/ubuntu/benchmarks/UnixBench/testdir"
>> Jan 14 11:19:37 hostname kernel: [4981461.529458] type=1302 audit(1421234377.184:894228556): item=0 name="/home/ubuntu/benchmarks/UnixBench/results/" inode=396144 dev=ca:01 mode=040775 ouid=1000 ogid=1000 rdev=00:00
>> Jan 14 11:19:37 hostname kernel: [4981461.529460] type=1302 audit(1421234377.184:894228556): item=1 name=(null) inode=440344 dev=ca:01 mode=0100664 ouid=1000 ogid=1000 rdev=00:00
>> Jan 14 11:19:37 hostname kernel: [4981461.529463] type=1302 audit(1421234377.184:894228556): item=2 name=(null) inode=440344 dev=ca:01 mode=0100664 ouid=1000 ogid=1000 rdev=00:00
>> 
>> I investigated audit source code a bit and found out that these are produced as
>> a result of enumerations over audit_context.names_list data structure. But, I'm
>> still not clear how and when entries for this data structure are filled.
> 
> There has been active work done recently to fix this problem.  Your case
> #2 is clearly an example of what we've been seeing.
> 
> Paul Moore sent a patch in early December and another at the end of
> December, followed by a patchset from January 8th in an attempt to clean
> things up for good:
> 	https://www.redhat.com/archives/linux-audit/2014-December/msg00001.html <https://www.redhat.com/archives/linux-audit/2014-December/msg00001.html>
> 		audit: correctly record file names with different path name types
> 	https://www.redhat.com/archives/linux-audit/2014-December/msg00108.html <https://www.redhat.com/archives/linux-audit/2014-December/msg00108.html>
> 		audit: create private file name copies when auditing inodes
> 	https://www.redhat.com/archives/linux-audit/2015-January/msg00016.html <https://www.redhat.com/archives/linux-audit/2015-January/msg00016.html>
> 		"Overhaul the audit filename handling"
> 
> See also:
> 	https://bugzilla.redhat.com/show_bug.cgi?id=1155208 <https://bugzilla.redhat.com/show_bug.cgi?id=1155208>
> 
>> Could anyone explain what would it mean to have multiple items (paths) means for
>> a single open syscall invocation?
> 
> Usually directory and file.
> 
>> Thanks a lot for your help in advance. 
>> 
>> Regards, Kangkook
> 
> - RGB
> 
> --
> Richard Guy Briggs <rbriggs at redhat.com <mailto:rbriggs at redhat.com>>
> Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
> Remote, Ottawa, Canada
> Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545

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