cgroup updates: fix several bugs

1. add cgroup_get_subsys_abspath() which returns the absolute
path for a subsystem mount, and use that where needed to actually
set cgroup values

2. cgroup_devices_has_{allow,deny}: don't mix int and boolean
values.  Also, accept 'a *:* rwm" as any whitelist entry for
has_allow().

3. subsys_lists_match(): fix an off-by-one error in calculating
updated oldlen.  (we need to keep the extra char for '\0')

4. return -1, not 0, if lxc_cgroup_attach fails to open
/proc/self/cgroup.

Signed-off-by: Ubuntu <ubuntu@ip-10-181-158-15.ec2.internal>

diff --git a/src/lxc/cgroup.c b/src/lxc/cgroup.c
index 12787a33260d8bf0dfba35d69d6e5a93ab75f4d8..014c40829ca9dcb2fcd93e75774c6220c64d1e0f 100644 (file)
--- a/src/lxc/cgroup.c
+++ b/src/lxc/cgroup.c
@@ -287,6 +287,35 @@ static int do_cgroup_set(const char *path, const char *value)
        return 0;
 }
 
+static int in_subsys_list(const char *s, const char *list)
+{
+       char *token, *str, *saveptr = NULL;
+
+       if (!list || !s)
+               return 0;
+
+       str = alloca(strlen(list)+1);
+       strcpy(str, list);
+       for (; (token = strtok_r(str, ",", &saveptr)); str = NULL) {
+               if (strcmp(s, token) == 0)
+                       return 1;
+       }
+
+       return 0;
+}
+
+static char *cgroup_get_subsys_abspath(struct lxc_handler *handler, const char *subsys)
+{
+       struct cgroup_desc *d;
+
+       for (d = handler->cgroup; d; d = d->next) {
+               if (in_subsys_list(subsys, d->subsystems))
+                       return d->curcgroup;
+       }
+
+       return NULL;
+}
+
 static bool cgroup_devices_has_deny(struct lxc_handler *h, char *v)
 {
        char *cgabspath, path[MAXPATHLEN];
@@ -294,24 +323,25 @@ static bool cgroup_devices_has_deny(struct lxc_handler *h, char *v)
        char *line = NULL;
        size_t len = 0;
        bool ret = true;
+       int r;
 
        // XXX FIXME if users could use something other than 'lxc.devices.deny = a'.
        // not sure they ever do, but they *could*
        // right now, I'm assuming they do NOT
        if (strcmp(v, "a") && strcmp(v, "a *:* rwm"))
                return false;
-       cgabspath = cgroup_get_subsys_path(h, "devices");
+       cgabspath = cgroup_get_subsys_abspath(h, "devices");
        if (!cgabspath)
-               return -1;
+               return false;
 
-       ret = snprintf(path, MAXPATHLEN, "%s/devices.list", cgabspath);
-       if (ret < 0 || ret >= MAXPATHLEN) {
+       r = snprintf(path, MAXPATHLEN, "%s/devices.list", cgabspath);
+       if (r < 0 || r >= MAXPATHLEN) {
                ERROR("pathname too long for devices.list");
-               return -1;
+               return false;
        }
 
        if (!(f = fopen(path, "r")))
-               return -1;
+               return false;
 
        while (getline(&line, &len, f) != -1) {
                size_t len = strlen(line);
@@ -333,29 +363,31 @@ out:
 static bool cgroup_devices_has_allow(struct lxc_handler *h, char *v)
 {
        char *cgabspath, path[MAXPATHLEN];
+       int r;
        bool ret = false;
        FILE *f;
        char *line = NULL;
        size_t len = 0;
 
-       cgabspath = cgroup_get_subsys_path(h, "devices");
+       cgabspath = cgroup_get_subsys_abspath(h, "devices");
        if (!cgabspath)
-               return -1;
+               return false;
 
-       ret = snprintf(path, MAXPATHLEN, "%s/devices.list", cgabspath);
-       if (ret < 0 || ret >= MAXPATHLEN) {
+       r = snprintf(path, MAXPATHLEN, "%s/devices.list", cgabspath);
+       if (r < 0 || r >= MAXPATHLEN) {
                ERROR("pathname too long to for devices.list");
-               return -1;
+               return false;
        }
 
        if (!(f = fopen(path, "r")))
-               return -1;
+               return false;
 
        while (getline(&line, &len, f) != -1) {
-               size_t len = strlen(line);
-               if (len > 0 && line[len-1] == '\n')
+               if (len < 1)
+                       goto out;
+               if (line[len-1] == '\n')
                        line[len-1] = '\0';
-               if (strcmp(line, v) == 0) {
+               if (strcmp(line, "a *:* rwm") == 0 || strcmp(line, v) == 0) {
                        ret = true;
                        goto out;
                }
@@ -388,7 +420,7 @@ int lxc_cgroup_set_value(struct lxc_handler *handler, const char *filename,
                return -1;
        if ((p = index(path, '.')) != NULL)
                *p = '\0';
-       cgabspath = cgroup_get_subsys_path(handler, path);
+       cgabspath = cgroup_get_subsys_abspath(handler, path);
        if (!cgabspath)
                return -1;
 
@@ -544,23 +576,6 @@ int lxc_cgroup_nrtasks(struct lxc_handler *handler)
        return ret;
 }
 
-static int in_subsys_list(const char *s, const char *list)
-{
-       char *token, *str, *saveptr = NULL;
-
-       if (!list || !s)
-               return 0;
-
-       str = alloca(strlen(list)+1);
-       strcpy(str, list);
-       for (; (token = strtok_r(str, ",", &saveptr)); str = NULL) {
-               if (strcmp(s, token) == 0)
-                       return 1;
-       }
-
-       return 0;
-}
-
 static int subsys_lists_match(const char *list1, const char *list2)
 {
        char *token, *str, *saveptr = NULL;
@@ -646,7 +661,7 @@ static char *record_visited(char *opts, char *all_subsystems)
                else
                        *visited = '\0';
                strcat(visited, token);
-               oldlen += toklen + (oldlen ? 1 : 0);
+               oldlen = newlen;
        }
 
        return visited;
@@ -1166,7 +1181,7 @@ int lxc_cgroup_attach(pid_t pid, const char *name, const char *lxcpath)
        /* read the list of subsystems from the kernel */
        f = fopen("/proc/cgroups", "r");
        if (!f)
-               return ret;
+               return -1;
 
        while (getline(&line, &len, f) != -1) {
                char *c;