[PATCH] conf: Stop parsing options at first non-option argument

[Stefano Brivio <sbrivio@redhat.com>]

Given that pasta supports specifying a command to be executed on the
command line, even without the usual -- separator as long as there's
no ambiguity, we shouldn't eat up options that are not meant for us.

Paul reports, for instance, that with:

  pasta --config-net ip -6 route

-6 is taken by pasta to mean --ipv6-only, and we execute 'ip route'.
That's because getopt_long(), by default, shuffles the argument list
to shift non-option arguments at the end.

Avoid that by adding '-' at the beginning of 'optstring', and mark the
position of the first non-option argument (getopt_long() will now
return the character code 1 once we hit it), so that we can use that
as command to run, or as PID for the target namespace.

Reported-by: Paul Holzinger <pholzing@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 conf.c | 22 +++++++++++++++-------
 util.c |  2 +-
 2 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/conf.c b/conf.c
index 5422813..a3e15f0 100644
--- a/conf.c
+++ b/conf.c
@@ -1240,21 +1240,21 @@ void conf(struct ctx *c, int argc, char **argv)
 	enum fwd_ports_mode fwd_default = FWD_NONE;
 	bool v4_only = false, v6_only = false;
 	struct fqdn *dnss = c->dns_search;
+	int name, ret, first_nonopt = -1;
 	unsigned int ifi4 = 0, ifi6 = 0;
 	const char *logfile = NULL;
 	const char *optstring;
 	size_t logsize = 0;
 	char *runas = NULL;
-	int name, ret;
 	uid_t uid;
 	gid_t gid;
 
 	if (c->mode == MODE_PASTA) {
 		c->no_dhcp_dns = c->no_dhcp_dns_search = 1;
 		fwd_default = FWD_AUTO;
-		optstring = "dqfel:hF:I:p:P:m:a:n:M:g:i:o:D:S:46t:u:T:U:";
+		optstring = "-dqfel:hF:I:p:P:m:a:n:M:g:i:o:D:S:46t:u:T:U:";
 	} else {
-		optstring = "dqfel:hs:F:p:P:m:a:n:M:g:i:o:D:S:461t:u:";
+		optstring = "-dqfel:hs:F:p:P:m:a:n:M:g:i:o:D:S:461t:u:";
 	}
 
 	c->tcp.fwd_in.mode = c->tcp.fwd_out.mode = FWD_UNSET;
@@ -1268,6 +1268,10 @@ void conf(struct ctx *c, int argc, char **argv)
 		case -1:
 		case 0:
 			break;
+		case 1:
+			first_nonopt = optind - 1;
+			name = -1;
+			break;
 		case 2:
 			if (c->mode != MODE_PASTA)
 				die("--userns is for pasta mode only");
@@ -1629,6 +1633,9 @@ void conf(struct ctx *c, int argc, char **argv)
 		}
 	} while (name != -1);
 
+	if (first_nonopt == -1)
+		first_nonopt = optind;
+
 	if (c->mode == MODE_PASTA && !c->pasta_conf_ns) {
 		if (copy_routes_opt)
 			die("--no-copy-routes needs --config-net");
@@ -1687,9 +1694,9 @@ void conf(struct ctx *c, int argc, char **argv)
 	} while (name != -1);
 
 	if (c->mode == MODE_PASTA)
-		conf_pasta_ns(&netns_only, userns, netns, optind, argc, argv);
-	else if (optind != argc)
-		die("Extra non-option argument: %s", argv[optind]);
+		conf_pasta_ns(&netns_only, userns, netns, first_nonopt, argc, argv);
+	else if (first_nonopt != argc)
+		die("Extra non-option argument: %s", argv[first_nonopt]);
 
 	conf_open_files(c);	/* Before any possible setuid() / setgid() */
 
@@ -1703,7 +1710,8 @@ void conf(struct ctx *c, int argc, char **argv)
 			pasta_open_ns(c, netns);
 		} else {
 			pasta_start_ns(c, uid, gid,
-				       argc - optind, argv + optind);
+				       argc - first_nonopt,
+				       argv + first_nonopt);
 		}
 	}
 
diff --git a/util.c b/util.c
index 9c6be6a..13524e6 100644
--- a/util.c
+++ b/util.c
@@ -710,7 +710,7 @@ void close_open_files(int argc, char **argv)
 	int name;
 
 	do {
-		name = getopt_long(argc, argv, ":F", optfd, NULL);
+		name = getopt_long(argc, argv, "-:F", optfd, NULL);
 
 		if (name == 'F') {
 			errno = 0;
-- 
@@ -710,7 +710,7 @@ void close_open_files(int argc, char **argv)
 	int name;
 
 	do {
-		name = getopt_long(argc, argv, ":F", optfd, NULL);
+		name = getopt_long(argc, argv, "-:F", optfd, NULL);
 
 		if (name == 'F') {
 			errno = 0;
-- 
2.43.0