Add gid to clixon_process_register() for drop privs

CHANGELOG.md

@@ -54,7 +54,7 @@ Expected: July 2023
 ### C/CLI-API changes on existing features
 Developers may need to change their code
 
-* Added `uid` parameter to `clixon_process_register()`
+* Added `uid` and `gid` parameters to `clixon_process_register()` for drop privs
 * Added output function to JSON output:
   * `xml2json_vec(...,skiptop)` --> `xml2json_vec(..., cligen_output, skiptop)`
 * `yang2cli_yspec` removed last argument `printgen`.

apps/backend/backend_plugin_restconf.c

@@ -314,7 +314,7 @@ restconf_pseudo_process_control(clicon_handle h)
     if (clixon_process_register(h, RESTCONF_PROCESS,
                                 "Clixon RESTCONF process",
                                 NULL /* XXX network namespace */,
-                                -1,
+                                -1, -1,
                                 restconf_rpc_wrapper,
                                 argv, nr) < 0)
         goto done;

lib/clixon/clixon_proc.h

@@ -70,7 +70,7 @@ int clixon_proc_socket_close(pid_t pid, int sock);
 int clixon_process_pid(clicon_handle h, const char *name, pid_t *pid);
 proc_operation clixon_process_op_str2int(char *opstr);
 int clixon_process_argv_get(clicon_handle h, const char *name, char ***argv, int *argc);
-int clixon_process_register(clicon_handle h, const char *name, const char *descr, const char *netns, uid_t uid, proc_cb_t *callback, char **argv, int argc);
+int clixon_process_register(clicon_handle h, const char *name, const char *descr, const char *netns, uid_t uid, gid_t gid, proc_cb_t *callback, char **argv, int argc);
 int clixon_process_delete_all(clicon_handle h);
 int clixon_process_operation(clicon_handle h, const char *name, proc_operation op, const int wrapit);
 int clixon_process_status(clicon_handle h, const char *name, cbuf *cbret);

lib/clixon/clixon_string.h

@@ -107,7 +107,6 @@ char  *clixon_trim(char *str);
 char  *clixon_trim2(char *str, char *trims);
 int    clicon_strcmp(char *s1, char *s2);
 
-
 #ifndef HAVE_STRNDUP
 char *clicon_strndup (const char *, size_t);
 #endif /* ! HAVE_STRNDUP */

lib/src/clixon_proc.c

@@ -146,6 +146,7 @@ struct process_entry_t {
     char          *pe_description; /* Description of service */
     char          *pe_netns;    /* Network namespace */
     uid_t          pe_uid;      /* UID of process or -1 to keep same as backend */
+    gid_t          pe_gid;      /* GID of process or -1 to keep same as backend */
     char         **pe_argv;     /* argv with command as element 0 and NULL-terminated */
     int            pe_argc;     /* Length of argc */
     pid_t          pe_pid;      /* Running process id (state) or 0 if dead (pid is set if exiting=1) */
@@ -273,6 +274,7 @@ static int
 clixon_proc_background(char       **argv,
                        const char  *netns,
                        uid_t        uid,
+                       gid_t        gid,
                        pid_t       *pid0)
 {
     int           retval = -1;
@@ -313,10 +315,7 @@ clixon_proc_background(char       **argv,
         char nsfile[PATH_MAX];
         int  nsfd;
 #endif
-        if (uid != -1){
+
-            if (drop_priv_perm(uid) < 0)
-                goto done;
-        }
         clicon_debug(1, "%s child", __FUNCTION__);
         clicon_signal_unblock(0);
         signal(SIGTSTP, SIG_IGN);
@@ -352,6 +351,16 @@ clixon_proc_background(char       **argv,
             }
         }
 #endif /* HAVE_SETNS */
+        if (gid != -1){
+            if (setgid(gid) == -1) {
+                clicon_err(OE_DAEMON, errno, "setgid %d", gid);
+                goto done;
+            }
+        }
+        if (uid != -1){
+            if (drop_priv_perm(uid) < 0)
+                goto done;
+        }
         if (execvp(argv[0], argv) < 0) {
             clicon_err(OE_UNIX, errno, "execv(%s)", argv[0]);
             exit(1);
@@ -435,6 +444,7 @@ clixon_process_argv_get(clicon_handle h,
  * @param[in]  description  Description of process
  * @param[in]  netns    Namespace netspace (or NULL)
  * @param[in]  uid      UID of process (or -1 to keep same)
+ * @param[in]  gid      GID of process (or -1 to keep same)
  * @param[in]  callback Wrapper function
  * @param[in]  argv     NULL-terminated vector of vectors 
  * @param[in]  argc     Length of argv
@@ -448,6 +458,7 @@ clixon_process_register(clicon_handle h,
                         const char   *description,
                         const char   *netns,
                         const uid_t   uid,
+                        const gid_t   gid,
                         proc_cb_t    *callback,
                         char        **argv,
                         int           argc)
@@ -482,6 +493,7 @@ clixon_process_register(clicon_handle h,
         goto done;
     }
     pe->pe_uid = uid;
+    pe->pe_gid = gid;
     pe->pe_argc = argc;
     if ((pe->pe_argv = calloc(argc, sizeof(char *))) == NULL){
         clicon_err(OE_UNIX, errno, "calloc");
@@ -852,7 +864,8 @@ clixon_process_sched(int           fd,
                         goto done;
                     if (!isrunning)
                         if (clixon_proc_background(pe->pe_argv, pe->pe_netns,
-                                                   pe->pe_uid, &pe->pe_pid) < 0)
+                                                   pe->pe_uid, pe->pe_gid,
+                                                   &pe->pe_pid) < 0)
                             goto done;
                     clicon_debug(1, "%s %s(%d) %s --%s--> %s", __FUNCTION__,
                                  pe->pe_name, pe->pe_pid,
@@ -878,7 +891,8 @@ clixon_process_sched(int           fd,
                     if (isrunning) /* Already runs */
                         break;
                     if (clixon_proc_background(pe->pe_argv, pe->pe_netns,
-                                               pe->pe_uid, &pe->pe_pid) < 0)
+                                               pe->pe_uid, pe->pe_gid,
+                                               &pe->pe_pid) < 0)
                         goto done;
                     clicon_debug(1, "%s %s(%d) %s --%s--> %s", __FUNCTION__,
                                  pe->pe_name, pe->pe_pid,
@@ -982,7 +996,8 @@ clixon_process_waitpid(clicon_handle h)
                     /* This is the case where there is an existing process running.
                      * it was killed above but still runs and needs to be reaped */
                     if (clixon_proc_background(pe->pe_argv, pe->pe_netns,
-                                               pe->pe_uid, &pe->pe_pid) < 0)
+                                               pe->pe_uid, pe->pe_gid,
+                                               &pe->pe_pid) < 0)
                         goto done;
                     gettimeofday(&pe->pe_starttime, NULL);
                     clicon_debug(1, "%s %s(%d) %s --%s--> %s", __FUNCTION__,