Couldn't get audit messages for 'listen' on kernel 4.19.0-6-686-pae
Steve Grubb
sgrubb at redhat.com
Mon Oct 23 16:19:46 UTC 2023
On Monday, October 23, 2023 9:06:16 AM EDT Rinat Gadelshin wrote:
> Hello there!
>
> First of all, I have to apologize for two identical emails as the
> beginning of the stream.
> The first one was sent (by occasional) from my work email.
> I've received notification, from the mail bot, that I should subscribe
> to the mail list (for the work email).
> After that I've resent the second one.
>
> Let's return to the problem.
>
> I've done a following experiment:
>
> `auditctl -D`
> `auditctl -a always,exit -S all`
> `strace netcat -v -l -p 4242 | tee strace.log` # the pid of the netcat
> was 536
> Ctrl+c
> `ausearch -p 536 > auditd.pid.536.log`
> `grep "syscall=.*traditional" auditd.pid.536.log | awk '{print $4}' |
> sort | uniq -c'
>
> The last command prints the following result:
>
> 11 syscall=102
> 1 syscall=11
> 6 syscall=125
> 6 syscall=140
> 6 syscall=174
> 1 syscall=175
> 14 syscall=192
> 33 syscall=195
> 9 syscall=197
> 2 syscall=20
> 1 syscall=243
> 1 syscall=27
> 41 syscall=295
> 14 syscall=3
> 5 syscall=33
> 2 syscall=4
> 5 syscall=45
> 11 syscall=6
> 3 syscall=91
>
> So the following syscalls are reported (there are no `socket`, `bind`,
> `connect`, `listen`):
>
> 3 (read)
> 4 (write)
> 6 (close)
> 11 (execve)
> 20 (getpid)
> 27 (alarm)
> 33 (access)
> 45 (brk)
> 91 (munmap)
> 102 (socketcall)
On old 386 kernels, they use socketcall as the networking API. Glibc under
the hood sets arg0 to a number which represents the actual functionality to
call and calls socketcall. You could say it multiplexes the network API.
Somewhere along the way, they decided to modernize and make actual calls for
each network function. So, if you have an audit library that is much newer
than the kernel, it will assume you are using the updated API rather than the
socketcall based API. In this case, you have an old glibc which still uses
socketcall.
So, if you wanted to audit socket, bind, connect, and listen you would use:
-a always,exit -F arch=b32 -S socketcall -F arg0=1 -F key=socket
-a always,exit -F arch=b32 -S socketcall -F arg0=2 -F key=bind
-a always,exit -F arch=b32 -S socketcall -F arg0=3 -F key=connect
-a always,exit -F arch=b32 -S socketcall -F arg0=4 -F key=listen
A listing of the numbers to use can be found at:
/usr/include/linux/net.h
Hope this helps...
-Steve
> 125 (mprotect)
> 140 (_llseek)
> 174 (rt_sigaction)
> 175 (rt_sigprocmask)
> 192 (mmap2)
> 195 (stat64)
> 197 (fstat64)
> 243 (set_thread_area)
> 295 (openat)
>
> But strace's log shows that `socket`, `bind`, `connect` and `listen`
> were called:
>
> execve("/usr/bin/netcat", ["netcat", "-v", "-l", "-p", "4242"],
> 0xbf9f8f00 /* 22 vars */) = 0
> -- line skipped --
> socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 3
> connect(3, {sa_family=AF_UNIX, sun_path="/var/run/nscd/socket"},
> 110) = -1 ENOENT (No such file or directory)
> close(3) = 0
> -- line skipped --
> socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 3
> connect(3, {sa_family=AF_UNIX, sun_path="/var/run/nscd/socket"},
> 110) = -1 ENOENT (No such file or directory)
> close(3) = 0
> -- line skipped --
> socket(AF_INET, SOCK_STREAM, IPPROTO_TCP) = 3
> setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
> setsockopt(3, SOL_SOCKET, SO_REUSEPORT, [1], 4) = 0
> bind(3, {sa_family=AF_INET, sin_port=htons(4242),
> sin_addr=inet_addr("0.0.0.0")}, 16) = 0
> listen(3, 1) = 0
> getsockname(3, {sa_family=AF_INET, sin_port=htons(4242),
> sin_addr=inet_addr("0.0.0.0")}, [16]) = 0
> -- line skipped --
>
> Please, give me a clue! How could it be?
>
> Best regards
> Rinat
>
> On 22.10.2023 08:27, Rinat Gadelshin wrote:
> > Hello there!
> >
> > I'm facing a strange problem.
> > I have not been able to get audit reports for any "network" syscall
> > on one of the computers from my test bench.
> > I mean 'connect', 'accept4', 'listen', 'bind', 'socket'.
> > The following example shows that auditd couldn't get them too
> > ('listen' at least).
> > But I've received a report about 'execve' called by the same process.
> >
> > Could you tell me what can I do in order to receive audit messages for
> > the syscalls.
> > from this version of the kernel?
> >
> > Any help will be will be appreciated.
> >
> >
> > root at deb101-x86-0009:~# netcat -v -l -p 4242 &
> > [2] 13481
> > root at deb101-x86-0009:~# listening on [any] 4242 ...
> > root at deb101-x86-0009:~# echo "Test" | nc -q 0 127.0.0.1 4242
> > connect to [127.0.0.1] from localhost [127.0.0.1] 36650
> > Test
> > root at deb101-x86-0009:~# skill -p 13481
> > [2]+ Done netcat -v -l -p 4242
> > root at deb101-x86-0009:~# ausearch -p 13481
> > ----
> > time->Fri Oct 20 22:00:42 2023
> > type=PROCTITLE msg=audit(1697828442.603:2697):
> > proctitle=6E6574636174002D76002D6C002D700034323432
> > type=PATH msg=audit(1697828442.603:2697): item=1
> > name="/lib/ld-linux.so.2" inode=655382 dev=fe:00 mode=0100755 ouid=0
> > ogid=0 rdev=00:00 nametype=NORMAL cap_fp=0000000000000000
> > cap_fi=0000000000000000 cap_fe=0 cap_fver=0
> > type=PATH msg=audit(1697828442.603:2697): item=0
> > name="/usr/bin/netcat" inode=664887 dev=fe:00 mode=0100755 ouid=0
> > ogid=0 rdev=00:00 nametype=NORMAL cap_fp=0000000000000000
> > cap_fi=0000000000000000 cap_fe=0 cap_fver=0
> > type=CWD msg=audit(1697828442.603:2697): cwd="/root"
> > type=EXECVE msg=audit(1697828442.603:2697): argc=5 a0="netcat" a1="-v"
> > a2="-l" a3="-p" a4="4242"
> > type=SYSCALL msg=audit(1697828442.603:2697): arch=40000003 syscall=11
> > success=yes exit=0 a0=e36400 a1=d9d9e0 a2=e3a310 a3=584988 items=2
> > ppid=12968 pid=13481 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0
> > sgid=0 fsgid=0 tty=pts1 ses=4 comm="netcat"
> > exe="/usr/bin/nc.traditional" subj==unconfined key=(null)
> > root at deb101-x86-0009:~# auditctl -l
> > -a always,exit -F arch=b32 -S fork,execve,clone,vfork,execveat
> > -a always,exit -F arch=b32 -S bind,connect,listen,accept4
> > root at deb101-x86-0009:~# auditctl -s
> > enabled 1
> > failure 1
> > pid 13393
> > rate_limit 0
> > backlog_limit 8192
> > lost 0
> > backlog 0
> > backlog_wait_time 0
> > loginuid_immutable 0 unlocked
> > root at deb101-x86-0009:~# uname -a
> > Linux deb101-x86-0009.avp.ru.local 4.19.0-6-686-pae #1 SMP Debian
> > 4.19.67-2+deb10u2 (2019-11-11) i686 GNU/Linux
> > root at deb101-x86-0009:~# cat /etc/debian_version
> > 10.1
> > root at deb101-x86-0009:~#
> >
> >
> > Regards
> > Rinat
>
> --
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