Paul Howarth wrote:
Since upgrading my mail server from Fedora 7 to Fedora 8, I've come
across some problems with the sockets used for communication between
sendmail and two of the "milter" plugins I'm using with it, namely
milter-regex and spamass-milter. It's very likely that other milters
will have similar issues.
The sockets used are created when the milter starts, as follows:
milter-regex:
/var/spool/milter-regex/sock (var_spool_t, inherited from parent directory)
spamass-milter:
/var/run/spamass-milter/spamass-milter.sock (spamd_var_run_t, in policy)
These are pretty well the upstream locations, though I'm open to moving
the milter-regex socket from /var/spool to /var/run or elsewhere for
consistency.
Since moving to Fedora 8, I've had to add the following to local policy
to get these milters working:
allow sendmail_t spamd_var_run_t:dir { search getattr };
allow sendmail_t spamd_var_run_t:sock_file { getattr write };
allow sendmail_t var_spool_t:sock_file { getattr write };
allow sendmail_t initrc_t:unix_stream_socket { read write connectto };
The last of these is the strangest, and relates to Bug #425958
(https://bugzilla.redhat.com/show_bug.cgi?id=425958). Whilst the socket
file itself has the context listed above, the unix domain socket that
sendmail connects to is still initrc_t, as can be seen from the output
of "netstat -lpZ":
...
unix 2 [ ACC ] STREAM LISTENING 14142
5853/spamass-milter system_u:system_r:initrc_t:s0
/var/run/spamass-milter/spamass-milter.sock
unix 2 [ ACC ] STREAM LISTENING 13794
5779/milter-regex system_u:system_r:initrc_t:s0
/var/spool/milter-regex/sock
...
So, my questions are:
1. Why are the sockets still initrc_t?
2. Is this a kernel issue or a userspace issue that should be fixed in
the milters?
3. Should there be a standard place for milter sockets to live, and if
so, where?
4. How come this worked OK in Fedora 7 and previous releases?
Looking at the source code for these applications, I see that both of
them use the smfi_setconn() function in the sendmail milter library to
set up the sockets. It's therefore likely that this problem is common to
all milter applications that use unix domain sockets.
I'm now of the opinion that moving the directory locations for these
sockets is a bad idea - it would need corresponding changes in people's
sendmail configuration files, which would lead to problems for people
doing package updates, or installing from upstream sources. Setting
different context types for the directories (e.g. make
/var/spool/milter-regex spamd_var_run_t) would seem a better option,
along with policy tweaks to allow sendmail to do the permissions checks
and write to the sockets).
I'm still confused about the initrc_t sockets though.
Paul.
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