udev: support custom Linux Security Module labels for device nodes

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>

4 files changed, 73 insertions, 7 deletions

diff --git a/src/udev/udev-event.c b/src/udev/udev-event.c
index 11ce364c40..7867263b81 100644
--- a/src/udev/udev-event.c
+++ b/src/udev/udev-event.c
@@ -47,6 +47,7 @@ struct udev_event *udev_event_new(struct udev_device *dev)
         event->dev = dev;
         event->udev = udev;
         udev_list_init(udev, &event->run_list, false);
+        udev_list_init(udev, &event->seclabel_list, false);
         event->fd_signal = -1;
         event->birth_usec = now(CLOCK_MONOTONIC);
         event->timeout_usec = 30 * 1000 * 1000;
@@ -58,6 +59,7 @@ void udev_event_unref(struct udev_event *event)
         if (event == NULL)
                 return;
         udev_list_cleanup(&event->run_list);
+        udev_list_cleanup(&event->seclabel_list);
         free(event->program_result);
         free(event->name);
         free(event);
@@ -987,7 +989,7 @@ int udev_event_execute_rules(struct udev_event *event, struct udev_rules *rules,
                         }
 
                         apply = streq(udev_device_get_action(dev), "add") || event->owner_set || event->group_set || event->mode_set;
-                        udev_node_add(dev, apply, event->mode, event->uid, event->gid);
+                        udev_node_add(dev, apply, event->mode, event->uid, event->gid, &event->seclabel_list);
                 }
 
                 /* preserve old, or get new initialization timestamp */
diff --git a/src/udev/udev-node.c b/src/udev/udev-node.c
index 4fca46495e..53529de4a7 100644
--- a/src/udev/udev-node.c
+++ b/src/udev/udev-node.c
@@ -28,6 +28,9 @@
 #include <sys/time.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#ifdef HAVE_XATTR
+#include <attr/xattr.h>
+#endif
 
 #include "udev.h"
 
@@ -252,11 +255,13 @@ void udev_node_update_old_links(struct udev_device *dev, struct udev_device *dev
         }
 }
 
-static int node_permissions_apply(struct udev_device *dev, bool apply, mode_t mode, uid_t uid, gid_t gid)
-{
+static int node_permissions_apply(struct udev_device *dev, bool apply,
+                                  mode_t mode, uid_t uid, gid_t gid,
+                                  struct udev_list *seclabel_list) {
         const char *devnode = udev_device_get_devnode(dev);
         dev_t devnum = udev_device_get_devnum(dev);
         struct stat stats;
+        struct udev_list_entry *entry;
         int err = 0;
 
         if (streq(udev_device_get_subsystem(dev), "block"))
@@ -286,7 +291,31 @@ static int node_permissions_apply(struct udev_device *dev, bool apply, mode_t mo
                 } else {
                         log_debug("preserve permissions %s, %#o, uid=%u, gid=%u\n", devnode, mode, uid, gid);
                 }
+
                 label_fix(devnode, true, false);
+
+                /* apply SECLABEL{$module}=$label */
+                udev_list_entry_foreach(entry, udev_list_get_entry(seclabel_list)) {
+                        const char *name, *label;
+
+                        name = udev_list_entry_get_name(entry);
+                        label = udev_list_entry_get_value(entry);
+
+                        if (streq(name, "selinux")) {
+                                /* FIXME: hook up libselinux */
+                                log_error("SECLABEL: failed to set selinux label '%s'", label);
+
+                        } else if (streq(name, "smack")) {
+#ifdef HAVE_XATTR
+                                if (lsetxattr(devnode, "security.SMACK64", label, strlen(label), 0) < 0)
+                                        log_error("SECLABEL: failed to set SMACK label '%s'", label);
+                                else
+                                        log_debug("SECLABEL: set SMACK label '%s'", label);
+#endif
+
+                        } else
+                                log_error("SECLABEL: unknown subsystem, ignoring '%s'='%s'", name, label);
+                }
         }
 
         /* always update timestamp when we re-use the node, like on media change events */
@@ -295,15 +324,16 @@ out:
         return err;
 }
 
-void udev_node_add(struct udev_device *dev, bool apply, mode_t mode, uid_t uid, gid_t gid)
-{
+void udev_node_add(struct udev_device *dev, bool apply,
+                   mode_t mode, uid_t uid, gid_t gid,
+                   struct udev_list *seclabel_list) {
         char filename[UTIL_PATH_SIZE];
         struct udev_list_entry *list_entry;
 
         log_debug("handling device node '%s', devnum=%s, mode=%#o, uid=%d, gid=%d\n",
                   udev_device_get_devnode(dev), udev_device_get_id_filename(dev), mode, uid, gid);
 
-        if (node_permissions_apply(dev, apply, mode, uid, gid) < 0)
+        if (node_permissions_apply(dev, apply, mode, uid, gid, seclabel_list) < 0)
                 return;
 
         /* always add /dev/{block,char}/$major:$minor */
diff --git a/src/udev/udev-rules.c b/src/udev/udev-rules.c
index 962102ebe7..c5dff9903c 100644
--- a/src/udev/udev-rules.c
+++ b/src/udev/udev-rules.c
@@ -156,6 +156,7 @@ enum token_type {
         TK_A_MODE_ID,                   /* mode_t */
         TK_A_TAG,                       /* val */
         TK_A_STATIC_NODE,               /* val */
+        TK_A_SECLABEL,                  /* val, attr */
         TK_A_ENV,                       /* val, attr */
         TK_A_NAME,                      /* val */
         TK_A_DEVLINK,                   /* val */
@@ -291,6 +292,7 @@ static const char *token_str(enum token_type type)
                 [TK_A_OWNER_ID] =               "A OWNER_ID",
                 [TK_A_GROUP_ID] =               "A GROUP_ID",
                 [TK_A_STATIC_NODE] =            "A STATIC_NODE",
+                [TK_A_SECLABEL] =               "A SECLABEL",
                 [TK_A_MODE_ID] =                "A MODE_ID",
                 [TK_A_ENV] =                    "A ENV",
                 [TK_A_TAG] =                    "A ENV",
@@ -399,6 +401,9 @@ static void dump_token(struct udev_rules *rules, struct token *token)
         case TK_A_STATIC_NODE:
                 log_debug("%s '%s'\n", token_str(type), value);
                 break;
+        case TK_A_SECLABEL:
+                log_debug("%s %s '%s' '%s'\n", token_str(type), operation_str(op), attr, value);
+                break;
         case TK_M_EVENT_TIMEOUT:
                 log_debug("%s %u\n", token_str(type), token->key.event_timeout);
                 break;
@@ -911,6 +916,7 @@ static int rule_add_key(struct rule_tmp *rule_tmp, enum token_type type,
         case TK_M_ATTRS:
         case TK_A_ATTR:
         case TK_A_ENV:
+        case TK_A_SECLABEL:
                 attr = data;
                 token->key.value_off = rules_add_string(rule_tmp->rules, value);
                 token->key.attr_off = rules_add_string(rule_tmp->rules, attr);
@@ -1158,6 +1164,17 @@ static int add_rule(struct udev_rules *rules, char *line,
                         continue;
                 }
 
+                if (startswith(key, "SECLABEL{")) {
+                        attr = get_key_attribute(rules->udev, key + sizeof("SECLABEL")-1);
+                        if (!attr) {
+                                log_error("error parsing SECLABEL attribute\n");
+                                goto invalid;
+                        }
+
+                        rule_add_key(&rule_tmp, TK_A_SECLABEL, op, value, attr);
+                        continue;
+                }
+
                 if (streq(key, "KERNELS")) {
                         if (op > OP_MATCH_MAX) {
                                 log_error("invalid KERNELS operation\n");
@@ -2399,6 +2416,20 @@ int udev_rules_apply_to_event(struct udev_rules *rules, struct udev_event *event
                                   rules_str(rules, rule->rule.filename_off),
                                   rule->rule.filename_line);
                         break;
+                case TK_A_SECLABEL: {
+                        const char *name, *label;
+
+                        name = rules_str(rules, cur->key.attr_off);
+                        label = rules_str(rules, cur->key.value_off);
+                        if (cur->key.op == OP_ASSIGN || cur->key.op == OP_ASSIGN_FINAL)
+                                udev_list_cleanup(&event->seclabel_list);
+                        udev_list_entry_add(&event->seclabel_list, name, label);
+                        log_debug("SECLABEL{%s}='%s' %s:%u\n",
+                                  name, label,
+                                  rules_str(rules, rule->rule.filename_off),
+                                  rule->rule.filename_line);
+                        break;
+                }
                 case TK_A_ENV: {
                         const char *name = rules_str(rules, cur->key.attr_off);
                         char *value = rules_str(rules, cur->key.value_off);
diff --git a/src/udev/udev.h b/src/udev/udev.h
index 760b678682..5e013d4f01 100644
--- a/src/udev/udev.h
+++ b/src/udev/udev.h
@@ -39,6 +39,7 @@ struct udev_event {
         mode_t mode;
         uid_t uid;
         gid_t gid;
+        struct udev_list seclabel_list;
         struct udev_list run_list;
         int exec_delay;
         usec_t birth_usec;
@@ -95,7 +96,9 @@ void udev_watch_end(struct udev *udev, struct udev_device *dev);
 struct udev_device *udev_watch_lookup(struct udev *udev, int wd);
 
 /* udev-node.c */
-void udev_node_add(struct udev_device *dev, bool apply, mode_t mode, uid_t uid, gid_t gid);
+void udev_node_add(struct udev_device *dev, bool apply,
+                   mode_t mode, uid_t uid, gid_t gid,
+                   struct udev_list *seclabel_list);
 void udev_node_remove(struct udev_device *dev);
 void udev_node_update_old_links(struct udev_device *dev, struct udev_device *dev_old);