touch-packages team mailing list archive

[John Johansen <john.johansen@xxxxxxxxxxxxx>]

So first off something is wrong with the decode
   google-nacl-o1d12356-391

does not contain any characters that would cause encoding to happen.
Doing a manual decode verifies that the issue is the trailing 0s.

The question still remains if this is a bug in apparmor grabbing the
abstract names length, or if the application is really specifying all
those null characters as part of the name.

So to the match patterns
> unix bind type=dgram addr=@google-nacl*,
> unix bind type=dgram addr="@google-nacl*",
Looking at the match generation * will not match \000 which will cause this to fail. This should be considered a bug since \000 is a valid character in abstract socket names

> unix bind type=dgram addr=@676F6F676C652D6E61636C2D6*,
> unix bind type=dgram addr="@676F6F676C652D6E61636C2D6*",
these are just incorrect apparmor rules don't support the hex encoding, this is something audit does when it encounters characters out of its printable alphanum range.

> unix bind type=dgram addr=@google-nacl*\\000*,
this won't work, perhaps you where thinking of regular re instead of apparmor's extended globbing?

> unix bind type=dgram addr=@google-nacl*[0-9a-
zA-Z]\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000{,\\000,\\000\\000},

this is closer but still will not work

The follow rule should match the number of trailing null characters
exactly, the audit encoding is hex so each two 0s is character which is
mapped to \x00 below. Basically I copied and pasted the trailing 0s and
insert \x every 2 00s. Currently there is no way to pattern match the
trailing 0s and they must be provided in the exact number. An
alternation can be used to vary the number but its is different than the
alternation above.

unix bind type=dgram addr="@google-
nacl*\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"


To vary the count of trailing nulls that are accepted we can use an alternation, however apparmor embedded alternation support can not handle a nesting level of 83, so the follow expression should but won't work until native parsing of aare is implemented
unix bind type=dgram addr="@google-nacl*{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00{\x00,},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},},}"

instead we have to use the less efficient (to compile) non-embedded alternation form
unix bind type=dgram addr="@google-nacl*{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}{\x00,}"

however there is one more twist, there is yet another bug preventing
expressing null in any way, \x00, \000 and \d00 all fail in the compile.
Specifying \\000 only expresses the literal character \ followed by 3
zeros

-- 
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https://bugs.launchpad.net/bugs/1413410

Title:
  Unable to match unix bind rule

Status in AppArmor Linux application security framework:
  New
Status in apparmor package in Ubuntu:
  New

Bug description:
  On Ubuntu 14.10, I had this in my logs:
  Jan 21 16:32:30 localhost kernel: [24900.927939] audit: type=1400 audit(1421879550.441:534): apparmor="DENIED" operation="bind" profile="/usr/lib/firefox/firefox{,*[^s][^h]}" pid=12356 comm="plugin-containe" family="unix" sock_type="dgram" protocol=0 requested_mask="bind" denied_mask="bind" addr="@676F6F676C652D6E61636C2D6F316431323335362D3339310000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"

  $ aa-decode 676F6F676C652D6E61636C2D6F316431323335362D3339310000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
  Decoded: google-nacl-o1d12356-391

  $ aa-decode 676F6F676C652D6E61636C2D6
  Decoded: google-nacl-`

  So I tried the following:
  unix bind type=dgram addr=@google-nacl*,
  unix bind type=dgram addr="@google-nacl*",
  unix bind type=dgram addr=@676F6F676C652D6E61636C2D6*,
  unix bind type=dgram addr="@676F6F676C652D6E61636C2D6*",
  unix bind type=dgram addr=@google-nacl*\\000*,
  unix bind type=dgram addr=@google-nacl*[0-9a-zA-Z]\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000{,\\000,\\000\\000},

  
  but none of them match. The best I could do was:
  unix bind type=dgram,

  This is likely going to be important for snappy since snappy will have the concept of different coordinating snaps interacting via abstract sockets. What is interesting is that this seems to work ok for some things, eg:
  ./lightdm:  unix (bind, listen) type=stream addr="@/com/ubuntu/upstart-session/**",
  ./lightdm:  unix (bind, listen) type=stream addr="@/tmp/dbus-*",
  ./lightdm:  unix (bind, listen) type=stream addr="@/tmp/.ICE-unix/[0-9]*",
  ./lightdm:  unix (bind, listen) type=stream addr="@/dbus-vfs-daemon/*",
  ./lightdm:  unix (bind, listen) type=stream addr="@guest*",

  Is this something in how firefox is setting up the socket?

  To reproduce, enable the firefox profile, start firefox and try to
  attend a google hangout.

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