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pasta: Allow specifying paths and names of namespaces
Based on a patch from Giuseppe Scrivano, this adds the ability to: - specify paths and names of target namespaces to join, instead of a PID, also for user namespaces, with --userns - request to join or create a network namespace only, without entering or creating a user namespace, with --netns-only - specify the base directory for netns mountpoints, with --nsrun-dir Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com> [sbrivio: reworked logic to actually join the given namespaces when they're not created, implemented --netns-only and --nsrun-dir, updated pasta demo script and man page] Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Giuseppe Scrivano
Stefano Brivio
parent
ab32838022
commit
9a175cc2ce
12 changed files with 240 additions and 79 deletions
157
conf.c
157
conf.c
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@ -96,7 +96,7 @@ static int get_bound_ports_ns(void *arg)
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struct get_bound_ports_ns_arg *a = (struct get_bound_ports_ns_arg *)arg;
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struct ctx *c = a->c;
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if (!c->pasta_pid || ns_enter(c->pasta_pid))
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if (!c->pasta_netns_fd || ns_enter(c))
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return 0;
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get_bound_ports(c, 1, a->proto);
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@ -588,6 +588,104 @@ out:
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warn("Couldn't get any nameserver address");
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}
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/**
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* conf_ns_check() - Check if we can enter configured namespaces
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* @arg: Execution context
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*
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* Return: 0
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*/
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static int conf_ns_check(void *arg)
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{
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struct ctx *c = (struct ctx *)arg;
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if ((!c->netns_only && setns(c->pasta_userns_fd, 0)) ||
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setns(c->pasta_netns_fd, 0))
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c->pasta_userns_fd = c->pasta_netns_fd = -1;
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return 0;
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}
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/**
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* conf_ns_opt() - Open network, user namespaces descriptors from configuration
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* @c: Execution context
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* @nsdir: --nsrun-dir argument, can be an empty string
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* @conf_userns: --userns argument, can be an empty string
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* @optarg: PID, path or name of namespace
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*
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* Return: 0 on success, negative error code otherwise
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*/
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static int conf_ns_opt(struct ctx *c,
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char *nsdir, char *conf_userns, const char *optarg)
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{
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char userns[PATH_MAX], netns[PATH_MAX];
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int ufd = 0, nfd = 0, try, ret;
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char *endptr;
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pid_t pid;
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if (c->netns_only && *conf_userns) {
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err("Both --userns and --netns-only given");
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return -EINVAL;
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}
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/* It might be a PID, a netns path, or a netns name */
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for (try = 0; try < 3; try++) {
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if (try == 0) {
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pid = strtol(optarg, &endptr, 10);
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if (*endptr || pid > INT_MAX)
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continue;
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if (!*conf_userns && !c->netns_only) {
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ret = snprintf(userns, PATH_MAX,
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"/proc/%i/ns/user", pid);
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if (ret <= 0 || ret > (int)sizeof(userns))
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continue;
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}
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ret = snprintf(netns, PATH_MAX, "/proc/%i/ns/net", pid);
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if (ret <= 0 || ret > (int)sizeof(netns))
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continue;
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} else if (try == 1) {
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if (!*conf_userns)
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c->netns_only = 1;
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ret = snprintf(netns, PATH_MAX, "%s", optarg);
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if (ret <= 0 || ret > (int)sizeof(userns))
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continue;
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} else if (try == 2) {
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ret = snprintf(netns, PATH_MAX, "%s/%s",
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*nsdir ? nsdir : NETNS_RUN_DIR, optarg);
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if (ret <= 0 || ret > (int)sizeof(netns))
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continue;
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}
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if (!c->netns_only) {
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if (*conf_userns)
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ufd = open(conf_userns, O_RDONLY);
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else if (*userns)
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ufd = open(userns, O_RDONLY);
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}
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nfd = open(netns, O_RDONLY);
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if (nfd >= 0 && ufd >= 0) {
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c->pasta_netns_fd = nfd;
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c->pasta_userns_fd = ufd;
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NS_CALL(conf_ns_check, c);
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if (c->pasta_netns_fd >= 0)
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return 0;
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}
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if (nfd > 0)
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close(nfd);
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if (ufd > 0)
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close(ufd);
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}
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return -ENOENT;
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}
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/**
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* usage() - Print usage and exit
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* @name: Executable name
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@ -595,10 +693,10 @@ out:
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static void usage(const char *name)
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{
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if (strstr(name, "pasta") || strstr(name, "passt4netns")) {
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info("Usage: %s [OPTION]... [TARGET_PID]", name);
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info("Usage: %s [OPTION]... [PID|PATH|NAME]", name);
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info("");
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info("Without TARGET_PID, enter a user and network namespace,");
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info("run the default shell and connect it via pasta.");
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info("Without PID|PATH|NAME, run the default shell in a new");
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info("network and user namespace, and connect it via pasta.");
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} else {
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info("Usage: %s [OPTION]...", name);
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}
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@ -670,7 +768,7 @@ static void usage(const char *name)
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info( " -6, --ipv6-only Enable IPv6 operation only");
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if (strstr(name, "pasta") || strstr(name, "passt4netns"))
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goto pasta_ports;
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goto pasta_opts;
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info( " -t, --tcp-ports SPEC TCP port forwarding to guest");
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info( " can be specified multiple times");
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@ -692,7 +790,7 @@ static void usage(const char *name)
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exit(EXIT_FAILURE);
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pasta_ports:
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pasta_opts:
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info( " -t, --tcp-ports SPEC TCP port forwarding to namespace");
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info( " can be specified multiple times");
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info( " SPEC can be:");
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@ -721,6 +819,11 @@ pasta_ports:
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info( " -U, --udp-ns SPEC UDP port forwarding to init namespace");
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info( " SPEC is as described above");
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info( " default: auto");
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info( " --userns NSPATH Target user namespace to join");
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info( " --netns-only Don't join or create user namespace");
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info( " implied if PATH or NAME are given without --userns");
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info( " --nsrun-dir Directory for nsfs mountpoints");
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info( " default: " NETNS_RUN_DIR);
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exit(EXIT_FAILURE);
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}
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@ -839,9 +942,13 @@ void conf(struct ctx *c, int argc, char **argv)
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{"udp-ports", required_argument, NULL, 'u' },
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{"tcp-ns", required_argument, NULL, 'T' },
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{"udp-ns", required_argument, NULL, 'U' },
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{"userns", required_argument, NULL, 2 },
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{"netns-only", no_argument, &c->netns_only, 1 },
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{"nsrun-dir", required_argument, NULL, 3 },
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{ 0 },
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};
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struct get_bound_ports_ns_arg ns_ports_arg = { .c = c };
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char nsdir[PATH_MAX] = { 0 }, userns[PATH_MAX] = { 0 };
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enum conf_port_type tcp_tap = 0, tcp_init = 0;
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enum conf_port_type udp_tap = 0, udp_init = 0;
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struct fqdn *dnss = c->dns_search;
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@ -863,10 +970,7 @@ void conf(struct ctx *c, int argc, char **argv)
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if ((name == 'p' || name == 'D' || name == 'S') && !optarg &&
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optind < argc && *argv[optind] && *argv[optind] != '-') {
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if (c->mode == MODE_PASTA) {
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char *endptr;
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strtol(argv[optind], &endptr, 10);
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if (*endptr)
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if (conf_ns_opt(c, nsdir, userns, argv[optind]))
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optarg = argv[optind++];
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} else {
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optarg = argv[optind++];
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@ -877,6 +981,30 @@ void conf(struct ctx *c, int argc, char **argv)
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case -1:
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case 0:
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break;
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case 2:
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if (c->mode != MODE_PASTA) {
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err("--userns is for pasta mode only");
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usage(argv[0]);
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}
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ret = snprintf(userns, sizeof(userns), "%s", optarg);
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if (ret <= 0 || ret >= (int)sizeof(userns)) {
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err("Invalid userns: %s", optarg);
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usage(argv[0]);
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}
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break;
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case 3:
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if (c->mode != MODE_PASTA) {
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err("--nsrun-dir is for pasta mode only");
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usage(argv[0]);
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}
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ret = snprintf(nsdir, sizeof(nsdir), "%s", optarg);
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if (ret <= 0 || ret >= (int)sizeof(nsdir)) {
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err("Invalid nsrun-dir: %s", optarg);
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usage(argv[0]);
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}
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break;
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case 'd':
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if (c->debug) {
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err("Multiple --debug options given");
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@ -1129,9 +1257,14 @@ void conf(struct ctx *c, int argc, char **argv)
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} while (name != -1);
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if (c->mode == MODE_PASTA && optind + 1 == argc) {
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c->pasta_pid = strtol(argv[optind], NULL, 0);
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if (c->pasta_pid < 0 || errno)
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ret = conf_ns_opt(c, nsdir, userns, argv[optind]);
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if (ret == -ENOENT)
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err("Namespace %s not found", argv[optind]);
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if (ret < 0)
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usage(argv[0]);
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} else if (c->mode == MODE_PASTA && *userns && optind == argc) {
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err("--userns requires PID, PATH or NAME");
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usage(argv[0]);
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} else if (optind != argc) {
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usage(argv[0]);
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}
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