conf: implement resource limits

configure.ac

@@ -639,7 +639,7 @@ AC_CHECK_DECLS([PR_SET_NO_NEW_PRIVS], [], [], [#include <sys/prctl.h>])
 AC_CHECK_DECLS([PR_GET_NO_NEW_PRIVS], [], [], [#include <sys/prctl.h>])
 
 # Check for some headers
-AC_CHECK_HEADERS([sys/signalfd.h pty.h ifaddrs.h sys/memfd.h sys/personality.h utmpx.h sys/timerfd.h])
+AC_CHECK_HEADERS([sys/signalfd.h pty.h ifaddrs.h sys/memfd.h sys/personality.h utmpx.h sys/timerfd.h sys/resource.h])
 
 # lookup major()/minor()/makedev()
 AC_HEADER_MAJOR

src/lxc/attach.c

@@ -894,6 +894,11 @@ int lxc_attach(const char* name, const char* lxcpath, lxc_attach_exec_t exec_fun
 				goto on_error;
 		}
 
+		/* Setup resource limits */
+		if (!lxc_list_empty(&init_ctx->container->lxc_conf->limits) && setup_resource_limits(&init_ctx->container->lxc_conf->limits, pid)) {
+			goto on_error;
+		}
+
 		/* Open /proc before setns() to the containers namespace so we
 		 * don't rely on any information from inside the container.
 		 */

src/lxc/conf.c

@@ -239,6 +239,11 @@ struct caps_opt {
 	int value;
 };
 
+struct limit_opt {
+	char *name;
+	int value;
+};
+
 /*
  * The lxc_conf of the container currently being worked on in an
  * API call
@@ -371,6 +376,57 @@ static struct caps_opt caps_opt[] = {
 static struct caps_opt caps_opt[] = {};
 #endif
 
+static struct limit_opt limit_opt[] = {
+#ifdef RLIMIT_AS
+	{ "as",          RLIMIT_AS          },
+#endif
+#ifdef RLIMIT_CORE
+	{ "core",        RLIMIT_CORE        },
+#endif
+#ifdef RLIMIT_CPU
+	{ "cpu",         RLIMIT_CPU         },
+#endif
+#ifdef RLIMIT_DATA
+	{ "data",        RLIMIT_DATA        },
+#endif
+#ifdef RLIMIT_FSIZE
+	{ "fsize",       RLIMIT_FSIZE       },
+#endif
+#ifdef RLIMIT_LOCKS
+	{ "locks",       RLIMIT_LOCKS       },
+#endif
+#ifdef RLIMIT_MEMLOCK
+	{ "memlock",     RLIMIT_MEMLOCK     },
+#endif
+#ifdef RLIMIT_MSGQUEUE
+	{ "msgqueue",    RLIMIT_MSGQUEUE    },
+#endif
+#ifdef RLIMIT_NICE
+	{ "nice",        RLIMIT_NICE        },
+#endif
+#ifdef RLIMIT_NOFILE
+	{ "nofile",      RLIMIT_NOFILE      },
+#endif
+#ifdef RLIMIT_NPROC
+	{ "nproc",       RLIMIT_NPROC       },
+#endif
+#ifdef RLIMIT_RSS
+	{ "rss",         RLIMIT_RSS         },
+#endif
+#ifdef RLIMIT_RTPRIO
+	{ "rtprio",      RLIMIT_RTPRIO      },
+#endif
+#ifdef RLIMIT_RTTIME
+	{ "rttime",      RLIMIT_RTTIME      },
+#endif
+#ifdef RLIMIT_SIGPENDING
+	{ "sigpending",  RLIMIT_SIGPENDING  },
+#endif
+#ifdef RLIMIT_STACK
+	{ "stack",       RLIMIT_STACK       },
+#endif
+};
+
 static int run_buffer(char *buffer)
 {
 	struct lxc_popen_FILE *f;
@@ -2473,6 +2529,45 @@ static int setup_network(struct lxc_list *network)
 	return 0;
 }
 
+static int parse_resource(const char *res) {
+	size_t i;
+	int resid = -1;
+
+	for (i = 0; i < sizeof(limit_opt)/sizeof(limit_opt[0]); ++i) {
+		if (strcmp(res, limit_opt[i].name) == 0)
+			return limit_opt[i].value;
+	}
+
+	/* try to see if it's numeric, so the user may specify
+	 * resources that the running kernel knows about but
+	 * we don't */
+	if (lxc_safe_int(res, &resid) == 0)
+		return resid;
+	return -1;
+}
+
+int setup_resource_limits(struct lxc_list *limits, pid_t pid) {
+	struct lxc_list *it;
+	struct lxc_limit *lim;
+	int resid;
+
+	lxc_list_for_each(it, limits) {
+		lim = it->elem;
+
+		resid = parse_resource(lim->resource);
+		if (resid < 0) {
+			ERROR("unknown resource %s", lim->resource);
+			return -1;
+		}
+
+		if (prlimit(pid, resid, &lim->limit, NULL) != 0) {
+			ERROR("failed to set limit %s: %s", lim->resource, strerror(errno));
+			return -1;
+		}
+	}
+	return 0;
+}
+
 /* try to move physical nics to the init netns */
 void lxc_restore_phys_nics_to_netns(int netnsfd, struct lxc_conf *conf)
 {
@@ -2559,6 +2654,7 @@ struct lxc_conf *lxc_conf_init(void)
 	lxc_list_init(&new->includes);
 	lxc_list_init(&new->aliens);
 	lxc_list_init(&new->environment);
+	lxc_list_init(&new->limits);
 	for (i=0; i<NUM_LXC_HOOKS; i++)
 		lxc_list_init(&new->hooks[i]);
 	lxc_list_init(&new->groups);
@@ -4178,6 +4274,31 @@ int lxc_clear_cgroups(struct lxc_conf *c, const char *key)
 	return 0;
 }
 
+int lxc_clear_limits(struct lxc_conf *c, const char *key)
+{
+	struct lxc_list *it, *next;
+	bool all = false;
+	const char *k = NULL;
+
+	if (strcmp(key, "lxc.limit") == 0)
+		all = true;
+	else if (strncmp(key, "lxc.limit.", sizeof("lxc.limit.")-1) == 0)
+		k = key + sizeof("lxc.limit.")-1;
+	else
+		return -1;
+
+	lxc_list_for_each_safe(it, &c->limits, next) {
+		struct lxc_limit *lim = it->elem;
+		if (!all && strcmp(lim->resource, k) != 0)
+			continue;
+		lxc_list_del(it);
+		free(lim->resource);
+		free(lim);
+		free(it);
+	}
+	return 0;
+}
+
 int lxc_clear_groups(struct lxc_conf *c)
 {
 	struct lxc_list *it,*next;
@@ -4320,6 +4441,7 @@ void lxc_conf_free(struct lxc_conf *conf)
 	lxc_clear_includes(conf);
 	lxc_clear_aliens(conf);
 	lxc_clear_environment(conf);
+	lxc_clear_limits(conf, "lxc.limit");
 	free(conf);
 }
 

src/lxc/conf.h

@@ -30,6 +30,9 @@
 #include <net/if.h>
 #include <sys/param.h>
 #include <sys/types.h>
+#if HAVE_SYS_RESOURCE_H
+#include <sys/resource.h>
+#endif
 #include <stdbool.h>
 
 #include "list.h"
@@ -149,6 +152,23 @@ struct lxc_cgroup {
 	char *value;
 };
 
+#if !HAVE_SYS_RESOURCE_H
+# define RLIM_INFINITY ((unsigned long)-1)
+struct rlimit {
+	unsigned long rlim_cur;
+	unsigned long rlim_max;
+};
+#endif
+/*
+ * Defines a structure to configure resource limits to set via setrlimit().
+ * @resource : the resource name in lowercase without the RLIMIT_ prefix
+ * @limit    : the limit to set
+ */
+struct lxc_limit {
+	char *resource;
+	struct rlimit limit;
+};
+
 enum idtype {
 	ID_TYPE_UID,
 	ID_TYPE_GID
@@ -385,6 +405,9 @@ struct lxc_conf {
 
 	/* Whether PR_SET_NO_NEW_PRIVS will be set for the container. */
 	bool no_new_privs;
+
+	/* RLIMIT_* limits */
+	struct lxc_list limits;
 };
 
 #ifdef HAVE_TLS
@@ -428,6 +451,7 @@ extern int lxc_clear_hooks(struct lxc_conf *c, const char *key);
 extern int lxc_clear_idmaps(struct lxc_conf *c);
 extern int lxc_clear_groups(struct lxc_conf *c);
 extern int lxc_clear_environment(struct lxc_conf *c);
+extern int lxc_clear_limits(struct lxc_conf *c, const char *key);
 extern int lxc_delete_autodev(struct lxc_handler *handler);
 
 extern int do_rootfs_setup(struct lxc_conf *conf, const char *name,
@@ -440,6 +464,8 @@ extern int do_rootfs_setup(struct lxc_conf *conf, const char *name,
 struct cgroup_process_info;
 extern int lxc_setup(struct lxc_handler *handler);
 
+extern int setup_resource_limits(struct lxc_list *limits, pid_t pid);
+
 extern void lxc_restore_phys_nics_to_netns(int netnsfd, struct lxc_conf *conf);
 
 extern int find_unmapped_nsuid(struct lxc_conf *conf, enum idtype idtype);

src/lxc/confile.c

@@ -121,6 +121,7 @@ static int config_init_uid(const char *, const char *, struct lxc_conf *);
 static int config_init_gid(const char *, const char *, struct lxc_conf *);
 static int config_ephemeral(const char *, const char *, struct lxc_conf *);
 static int config_no_new_privs(const char *, const char *, struct lxc_conf *);
+static int config_limit(const char *, const char *, struct lxc_conf *);
 
 static struct lxc_config_t config[] = {
 
@@ -195,6 +196,7 @@ static struct lxc_config_t config[] = {
 	{ "lxc.ephemeral",            config_ephemeral            },
 	{ "lxc.syslog",               config_syslog               },
 	{ "lxc.no_new_privs",	      config_no_new_privs	  },
+	{ "lxc.limit",                config_limit                },
 };
 
 struct signame {
@@ -1580,6 +1582,110 @@ out:
 	return -1;
 }
 
+static bool parse_limit_value(const char **value, unsigned long *res) {
+	char *endptr = NULL;
+
+	if (strncmp(*value, "unlimited", sizeof("unlimited")-1) == 0) {
+		*res = RLIM_INFINITY;
+		*value += sizeof("unlimited")-1;
+		return true;
+	}
+
+	errno = 0;
+	*res = strtoul(*value, &endptr, 10);
+	if (errno || !endptr)
+		return false;
+	*value = endptr;
+
+	return true;
+}
+
+static int config_limit(const char *key, const char *value,
+			 struct lxc_conf *lxc_conf)
+{
+	struct lxc_list *limlist = NULL;
+	struct lxc_limit *limelem = NULL;
+	struct lxc_list *iter;
+	struct rlimit limit;
+	unsigned long limit_value;
+
+	if (!value || strlen(value) == 0)
+		return lxc_clear_limits(lxc_conf, key);
+
+	if (strncmp(key, "lxc.limit.", sizeof("lxc.limit.")-1) != 0)
+		return -1;
+
+	key += sizeof("lxc.limit.")-1;
+
+	/* soft limit comes first in the value */
+	if (!parse_limit_value(&value, &limit_value))
+		return -1;
+	limit.rlim_cur = limit_value;
+
+	/* skip spaces and a colon */
+	while (isspace(*value))
+		++value;
+	if (*value == ':')
+		++value;
+	else if (*value) /* any other character is an error here */
+		return -1;
+	while (isspace(*value))
+		++value;
+
+	/* optional hard limit */
+	if (*value) {
+		if (!parse_limit_value(&value, &limit_value))
+			return -1;
+		limit.rlim_max = limit_value;
+		/* check for trailing garbage */
+		while (isspace(*value))
+			++value;
+		if (*value)
+			return -1;
+	} else {
+		/* a single value sets both hard and soft limit */
+		limit.rlim_max = limit.rlim_cur;
+	}
+
+	/* find existing list element */
+	lxc_list_for_each(iter, &lxc_conf->limits) {
+		limelem = iter->elem;
+		if (!strcmp(key, limelem->resource)) {
+			limelem->limit = limit;
+			return 0;
+		}
+	}
+
+	/* allocate list element */
+	limlist = malloc(sizeof(*limlist));
+	if (!limlist)
+		goto out;
+	
+	limelem = malloc(sizeof(*limelem));
+	if (!limelem)
+		goto out;
+	memset(limelem, 0, sizeof(*limelem));
+
+	limelem->resource = strdup(key);
+	if (!limelem->resource)
+		goto out;
+	limelem->limit = limit;
+
+	limlist->elem = limelem;
+
+	lxc_list_add_tail(&lxc_conf->limits, limlist);
+
+	return 0;
+
+out:
+	free(limlist);
+	if (limelem) {
+		free(limelem->resource);
+		free(limelem);
+	}
+	return -1;
+}
+
 static int config_idmap(const char *key, const char *value, struct lxc_conf *lxc_conf)
 {
 	char *token = "lxc.id_map";
@@ -2313,6 +2419,55 @@ static int lxc_get_cgroup_entry(struct lxc_conf *c, char *retv, int inlen,
 	return fulllen;
 }
 
+/*
+ * If you ask for a specific value, i.e. lxc.limit.nofile, then just the value
+ * will be printed. If you ask for 'lxc.limit', then all limit entries will be
+ * printed, in 'lxc.limit.resource = value' format.
+ */
+static int lxc_get_limit_entry(struct lxc_conf *c, char *retv, int inlen,
+				const char *key)
+{
+	int fulllen = 0, len;
+	int all = 0;
+	struct lxc_list *it;
+
+	if (!retv)
+		inlen = 0;
+	else
+		memset(retv, 0, inlen);
+
+	if (strcmp(key, "all") == 0)
+		all = 1;
+
+	lxc_list_for_each(it, &c->limits) {
+		char buf[LXC_NUMSTRLEN64*2+2]; /* 2 colon separated 64 bit integers or the word 'unlimited' */
+		int partlen;
+		struct lxc_limit *lim = it->elem;
+
+		if (lim->limit.rlim_cur == RLIM_INFINITY) {
+			memcpy(buf, "unlimited", sizeof("unlimited"));
+			partlen = sizeof("unlimited")-1;
+		} else {
+			partlen = sprintf(buf, "%lu", lim->limit.rlim_cur);
+		}
+		if (lim->limit.rlim_cur != lim->limit.rlim_max) {
+			if (lim->limit.rlim_max == RLIM_INFINITY) {
+				memcpy(buf+partlen, ":unlimited", sizeof(":unlimited"));
+			} else {
+				sprintf(buf+partlen, ":%lu", lim->limit.rlim_max);
+			}
+		}
+
+		if (all) {
+			strprint(retv, inlen, "lxc.limit.%s = %s\n", lim->resource, buf);
+		} else if (strcmp(lim->resource, key) == 0) {
+			strprint(retv, inlen, "%s", buf);
+		}
+	}
+
+	return fulllen;
+}
+
 static int lxc_get_item_hooks(struct lxc_conf *c, char *retv, int inlen,
 			      const char *key)
 {
@@ -2678,6 +2833,10 @@ int lxc_get_config_item(struct lxc_conf *c, const char *key, char *retv,
 		v = c->syslog;
 	else if (strcmp(key, "lxc.no_new_privs") == 0)
 		return lxc_get_conf_int(c, retv, inlen, c->no_new_privs);
+	else if (strcmp(key, "lxc.limit") == 0) // all limits
+		return lxc_get_limit_entry(c, retv, inlen, "all");
+	else if (strncmp(key, "lxc.limit.", 10) == 0) // specific limit
+		return lxc_get_limit_entry(c, retv, inlen, key + 10);
 	else return -1;
 
 	if (!v)
@@ -2711,6 +2870,8 @@ int lxc_clear_config_item(struct lxc_conf *c, const char *key)
 		return lxc_clear_environment(c);
 	else if (strncmp(key, "lxc.id_map", 10) == 0)
 		return lxc_clear_idmaps(c);
+	else if (strncmp(key, "lxc.limit", 9) == 0)
+		return lxc_clear_limits(c, key);
 	return -1;
 }
 

src/lxc/start.c

@@ -1261,6 +1261,11 @@ static int lxc_spawn(struct lxc_handler *handler)
 	if (lxc_sync_barrier_child(handler, LXC_SYNC_POST_CONFIGURE))
 		goto out_delete_net;
 
+	if (!lxc_list_empty(&handler->conf->limits) && setup_resource_limits(&handler->conf->limits, handler->pid)) {
+		ERROR("failed to setup resource limits for '%s'", name);
+		return -1;
+	}
+
 	if (!cgroup_setup_limits(handler, true)) {
 		ERROR("Failed to setup the devices cgroup for container \"%s\".", name);
 		goto out_delete_net;