sandbox: add a pre-connect sandbox

Add a sandbox enforced before options are parsed and the connection is
established to the XMPP server. This sandbox will allow network
operations.

The post-connect sandbox is unchanged and restricts operations to stdio.

The commit just adds the infrastructure for the pre-connect sandbox.

src/xmppipe.c

@@ -86,6 +86,12 @@ main(int argc, char **argv)
     jid = xmppipe_getenv("XMPPIPE_USERNAME");
     pass = xmppipe_getenv("XMPPIPE_PASSWORD");
 
+    if (state->verbose)
+        (void)fprintf(stderr, "sandbox: init: %s\n", XMPPIPE_SANDBOX);
+
+    if (xmppipe_sandbox_init(state) < 0)
+        err(EXIT_FAILURE, "sandbox failed");
+
     while ( (ch = getopt(argc, argv, "a:b:c:dDehI:k:K:o:P:p:r:sS:u:U:vx")) != -1) {
         switch (ch) {
             case 'u':
@@ -223,9 +229,9 @@ main(int argc, char **argv)
         errx(EXIT_FAILURE, "XMPP handshake failed");
 
     if (state->verbose)
-        (void)fprintf(stderr, "sandbox: entering %s\n", XMPPIPE_SANDBOX);
+        (void)fprintf(stderr, "sandbox: stdin: %s\n", XMPPIPE_SANDBOX);
 
-    if (xmppipe_sandbox_init(state) < 0)
+    if (xmppipe_sandbox_stdin(state) < 0)
         err(EXIT_FAILURE, "sandbox failed");
 
     if (xmppipe_stream_init(state) < 0)

src/xmppipe.h

@@ -120,6 +120,7 @@ void xmppipe_stanza_set_type(xmpp_stanza_t * const, const char * const);
 void xmppipe_stanza_add_child(xmpp_stanza_t *, xmpp_stanza_t *);
 
 int xmppipe_sandbox_init(xmppipe_state_t *state);
+int xmppipe_sandbox_stdin(xmppipe_state_t *state);
 int xmppipe_conn_fd(xmppipe_state_t *state);
 
 int b64_ntop(u_char const *src, size_t srclength, char *target,

src/xmppipe_sandbox_capsicum.c

@@ -25,6 +25,12 @@
 
     int
 xmppipe_sandbox_init(xmppipe_state_t *state)
+{
+    return 0;
+}
+
+    int
+xmppipe_sandbox_stdin(xmppipe_state_t *state)
 {
     struct rlimit rl;
     cap_rights_t policy_read;

src/xmppipe_sandbox_null.c

@@ -17,6 +17,12 @@
 
     int
 xmppipe_sandbox_init(xmppipe_state_t *state)
+{
+	return 0;
+}
+
+    int
+xmppipe_sandbox_stdin(xmppipe_state_t *state)
 {
 	return 0;
 }

src/xmppipe_sandbox_pledge.c

@@ -18,6 +18,12 @@
 
     int
 xmppipe_sandbox_init(xmppipe_state_t *state)
+{
+    return 0;
+}
+
+    int
+xmppipe_sandbox_stdin(xmppipe_state_t *state)
 {
     return pledge("stdio", NULL);
 }

src/xmppipe_sandbox_rlimit.c

@@ -20,6 +20,12 @@
 
     int
 xmppipe_sandbox_init(xmppipe_state_t *state)
+{
+    return 0;
+}
+
+    int
+xmppipe_sandbox_stdin(xmppipe_state_t *state)
 {
     struct rlimit rl_zero = {0};
     struct rlimit rl_nofile = {0};

src/xmppipe_sandbox_seccomp.c

@@ -75,6 +75,12 @@
 
     int
 xmppipe_sandbox_init(xmppipe_state_t *state)
+{
+    return 0;
+}
+
+    int
+xmppipe_sandbox_stdin(xmppipe_state_t *state)
 {
     struct sock_filter filter[] = {
         /* Ensure the syscall arch convention is as expected. */