BUG/MINOR: sock_unix: match finalname with tempname in sock_unix_addrcmp()

In sock_unix_addrcmp(), named UNIX sockets paths are manually compared in
order to properly handle tempname paths (ending with ".XXXX.tmp") that result
from the 2-step bind implemented in sock_unix_bind_receiver().

However, this logic does not take into account "final" path names (without the
".XXXX.tmp" suffix).

Example:
  /tmp/test did not match with /tmp/test.1288.tmp prior to this patch

Indeed, depending on how the socket addr is retrieved, the same socket
could be designated either by its tempname or finalname.
socket addr is normally stored with its finalname within a receiver, but a
call to getsockname() on the same socket will return the tempname that was
used for the bind() call (sock_get_old_sockets() depends on getsockname()).

This causes sock_find_compatible_fd() to malfunction with named UNIX
sockets (ie: haproxy -x CLI option).

To fix this, we slightly modify the check around the temp suffix in
sock_unix_addrcmp(): we perform the suffix check even if one of the
paths is lacking the temp suffix (with proper precautions).

Now the function is able to match:
  - finalname x finalname
  - tempname  x tempname
  - finalname x tempname

That is: /tmp/test == /tmp/test.1288.tmp == /tmp/test.X.tmp

It should be backported up to 2.4

diff --git a/src/sock_unix.c b/src/sock_unix.c
index 8a840fe3987b0b7235544345d6fbeb2fc41f9dc0..d549684c57a548caf96527ef5044eb21859bcaf2 100644 (file)
--- a/src/sock_unix.c
+++ b/src/sock_unix.c
@@ -93,7 +93,21 @@ int sock_unix_addrcmp(const struct sockaddr_storage *a, const struct sockaddr_st
 
        /* Now we have a difference. It's OK if they are within or after a
         * sequence of digits following a dot, and are followed by ".tmp".
+        *
+        * make sure to perform the check against tempname if the compared
+        * string is in "final" format (does not end with ".XXXX.tmp").
+        *
+        * Examples:
+        *     /tmp/test matches with /tmp/test.1822.tmp
+        *     /tmp/test.1822.tmp matches with /tmp/test.XXXX.tmp
         */
+       if (au->sun_path[idx] == 0 || bu->sun_path[idx] == 0) {
+               if (au->sun_path[idx] == '.' || bu->sun_path[idx] == '.')
+                       dot = idx; /* try to match against temp path */
+               else
+                       return -1; /* invalid temp path */
+       }
+
        if (!dot)
                return -1;