BUG/MEDIUM: listener: duplicate inherited FDs if needed
Since commit 36d9097cf ("MINOR: fd: Add BUG_ON checks on fd_insert()"),
there is currently a test in fd_insert() to detect that we're not trying
to reinsert an FD that had already been inserted. This test catches the
following anomalies:
frontend fail1
bind fd@0
bind fd@0
and:
frontend fail2
bind fd@0 shards 2
What happens is that clone_listener() is called on a listener already
having an FD, and when sock_{inet,unix}_bind_receiver() are called, the
same FD will be registered multiple times and rightfully crash in the
sanity check.
It wouldn't be correct to block shards though (e.g. they could be used
in a default-bind line). What looks like a safer and more future-proof
approach simply is to dup() the FD so that each listener has one copy.
This is also the only solution that might allow later to support more
than 64 threads on an inherited FD.
This needs to be backported as far as 2.4. Better wait for at least
one extra -dev version before backporting though, as the bug should
not be triggered often anyway.
(cherry picked from commit 145b17fd2f6857e45ca184419f29f41343446fc5)
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit 2aa96f003af84fc68b89efdfb4d6f1866f13788a)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit f1a031aca71dced4e66c36bf5878d2e976cbe9b0)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit d291b55abc8dec74b2839b4045d01222b87dd54d)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/src/sock_inet.c b/src/sock_inet.c
index fb69981..7523617 100644
--- a/src/sock_inet.c
+++ b/src/sock_inet.c
@@ -313,6 +313,24 @@
}
}
+ if (ext && fd < global.maxsock && fdtab[fd].owner) {
+ /* This FD was already bound so this means that it was already
+ * known and registered before parsing, hence it's an inherited
+ * FD. The only reason why it's already known here is that it
+ * has been registered multiple times (multiple listeners on the
+ * same, or a "shards" directive on the line). There cannot be
+ * multiple listeners on one FD but at least we can create a
+ * new one from the original one. We won't reconfigure it,
+ * however, as this was already done for the first one.
+ */
+ fd = dup(fd);
+ if (fd == -1) {
+ err |= ERR_RETRYABLE | ERR_ALERT;
+ memprintf(errmsg, "cannot dup() receiving socket (%s)", strerror(errno));
+ goto bind_return;
+ }
+ }
+
if (fd >= global.maxsock) {
err |= ERR_FATAL | ERR_ABORT | ERR_ALERT;
memprintf(errmsg, "not enough free sockets (raise '-n' parameter)");