RESPONDER: make all responders members of sssd group

Previously it was only for sssd_nss

TODO:
 - explanation
 - move to monitor/systemd service file

src/responder/common/responder.h

@@ -143,6 +143,12 @@ struct resp_ctx {
     bool socket_activated;
     bool cache_first;
     bool enumeration_warn_logged;
+
+#ifdef SSSD_NON_ROOT_USER
+    /* uid / gid of SSSD_USER */
+    uid_t uid;
+    gid_t gid;
+#endif /* SSSD_NON_ROOT_USER */
 };
 
 struct cli_creds;

src/responder/common/responder_common.c

@@ -1282,6 +1282,67 @@ static errno_t sss_get_etc_shells(TALLOC_CTX *mem_ctx, char ***_shells)
     return ret;
 }
 
+#ifdef SSSD_NON_ROOT_USER
+static int set_supplementary_group(gid_t gid)
+{
+    errno_t ret;
+    int size;
+    gid_t *supp_gids = NULL;
+
+    if (getgid() == gid) {
+        DEBUG(SSSDBG_TRACE_FUNC, "Already running as the sssd group\n");
+        return EOK;
+    }
+
+    size = getgroups(0, NULL);
+    if (size == -1) {
+        ret = errno;
+        DEBUG(SSSDBG_TRACE_FUNC, "Getgroups failed! (%d, %s)\n",
+                                    ret, sss_strerror(ret));
+        return ret;
+    }
+
+    if (size > 0) {
+        supp_gids = talloc_zero_array(NULL, gid_t, size);
+        if (supp_gids == NULL) {
+            DEBUG(SSSDBG_TRACE_FUNC, "Allocation failed!\n");
+            ret = ENOMEM;
+            goto done;
+        }
+
+        size = getgroups(size, supp_gids);
+        if (size == -1) {
+            ret = errno;
+            DEBUG(SSSDBG_TRACE_FUNC, "Getgroups failed! (%d, %s)\n",
+                                        ret, sss_strerror(ret));
+            goto done;
+        }
+
+        for (int i = 0; i < size; i++) {
+            if (supp_gids[i] == gid) {
+                DEBUG(SSSDBG_TRACE_FUNC,
+                      "Already assigned to the SSSD supplementary group\n");
+                ret = EOK;
+                goto done;
+            }
+        }
+    }
+
+    ret = setgroups(1, &gid);
+    if (ret != EOK) {
+        ret = errno;
+        DEBUG(SSSDBG_TRACE_FUNC,
+              "Cannot setgroups [%d]: %s\n", ret, sss_strerror(ret));
+        goto done;
+    }
+
+    ret = EOK;
+done:
+    talloc_free(supp_gids);
+    return ret;
+}
+#endif /* SSSD_NON_ROOT_USER */
+
 int sss_process_init(TALLOC_CTX *mem_ctx,
                      struct tevent_context *ev,
                      struct confdb_ctx *cdb,
@@ -1317,6 +1378,24 @@ int sss_process_init(TALLOC_CTX *mem_ctx,
     rctx->shutting_down = false;
     rctx->socket_activated = is_socket_activated();
 
+#ifdef SSSD_NON_ROOT_USER
+    /* In case SSSD is built with non-root user support,
+     * a number of files are sssd:sssd owned.
+     * If responder runs under root, add process to sssd
+     * supplementary group to avoid the need for
+     * CAP_DAC_OVERRIDE or CAP_CHOWN.
+     */
+    sss_sssd_user_uid_and_gid(&rctx->uid, &rctx->gid);
+    if ((getuid() == 0) || (geteuid() == 0)) {
+        ret = set_supplementary_group(rctx->gid);
+        if (ret != EOK) {
+            DEBUG(SSSDBG_CRIT_FAILURE,
+                  "Failed to add process to the sssd supplementary group\n");
+            goto fail;
+        }
+    }
+#endif /* SSSD_NON_ROOT_USER */
+
     talloc_set_destructor((TALLOC_CTX*)rctx, sss_responder_ctx_destructor);
 
     ret = confdb_get_int(rctx->cdb, rctx->confdb_service_path,

src/responder/nss/nss_private.h

@@ -93,8 +93,6 @@ struct sss_nss_ctx {
     struct sss_mc_ctx *grp_mc_ctx;
     struct sss_mc_ctx *initgr_mc_ctx;
     struct sss_mc_ctx *sid_mc_ctx;
-    uid_t mc_uid;
-    gid_t mc_gid;
 };
 
 struct sss_cmd_table *get_sss_nss_cmds(void);

src/responder/nss/nsssrv.c

@@ -57,6 +57,16 @@ sss_nss_clear_memcache(TALLOC_CTX *mem_ctx,
 {
     int memcache_timeout;
     errno_t ret;
+    uid_t uid;
+    gid_t gid;
+
+#ifdef SSSD_NON_ROOT_USER
+    uid = nctx->rctx->uid;
+    gid = nctx->rctx->gid;
+#else
+    uid = 0;
+    gid = 0;
+#endif /* SSSD_NON_ROOT_USER */
 
     if (access(SSS_NSS_MCACHE_DIR"/"CLEAR_MC_FLAG, F_OK) < 0) {
         ret = errno;
@@ -92,7 +102,7 @@ sss_nss_clear_memcache(TALLOC_CTX *mem_ctx,
     }
 
     DEBUG(SSSDBG_TRACE_FUNC, "Clearing memory caches.\n");
-    ret = sss_mmap_cache_reinit(nctx, nctx->mc_uid, nctx->mc_gid,
+    ret = sss_mmap_cache_reinit(nctx, uid, gid,
                                 -1, /* keep current size */
                                 (time_t) memcache_timeout,
                                 &nctx->pwd_mc_ctx);
@@ -102,7 +112,7 @@ sss_nss_clear_memcache(TALLOC_CTX *mem_ctx,
         goto done;
     }
 
-    ret = sss_mmap_cache_reinit(nctx, nctx->mc_uid, nctx->mc_gid,
+    ret = sss_mmap_cache_reinit(nctx, uid, gid,
                                 -1, /* keep current size */
                                 (time_t) memcache_timeout,
                                 &nctx->grp_mc_ctx);
@@ -112,7 +122,7 @@ sss_nss_clear_memcache(TALLOC_CTX *mem_ctx,
         goto done;
     }
 
-    ret = sss_mmap_cache_reinit(nctx, nctx->mc_uid, nctx->mc_gid,
+    ret = sss_mmap_cache_reinit(nctx, uid, gid,
                                 -1, /* keep current size */
                                 (time_t)memcache_timeout,
                                 &nctx->initgr_mc_ctx);
@@ -287,6 +297,16 @@ static int setup_memcaches(struct sss_nss_ctx *nctx)
     int mc_size_group;
     int mc_size_initgroups;
     int mc_size_sid;
+    uid_t uid;
+    gid_t gid;
+
+#ifdef SSSD_NON_ROOT_USER
+    uid = nctx->rctx->uid;
+    gid = nctx->rctx->gid;
+#else
+    uid = 0;
+    gid = 0;
+#endif /* SSSD_NON_ROOT_USER */
 
     /* Remove the CLEAR_MC_FLAG file if exists. */
     ret = unlink(SSS_NSS_MCACHE_DIR"/"CLEAR_MC_FLAG);
@@ -361,7 +381,7 @@ static int setup_memcaches(struct sss_nss_ctx *nctx)
     /* Initialize the fast in-memory caches if they were not disabled */
 
     ret = sss_mmap_cache_init(nctx, "passwd",
-                              nctx->mc_uid, nctx->mc_gid,
+                              uid, gid,
                               SSS_MC_PASSWD,
                               mc_size_passwd * SSS_MC_CACHE_SLOTS_PER_MB,
                               (time_t)memcache_timeout,
@@ -373,7 +393,7 @@ static int setup_memcaches(struct sss_nss_ctx *nctx)
     }
 
     ret = sss_mmap_cache_init(nctx, "group",
-                              nctx->mc_uid, nctx->mc_gid,
+                              uid, gid,
                               SSS_MC_GROUP,
                               mc_size_group * SSS_MC_CACHE_SLOTS_PER_MB,
                               (time_t)memcache_timeout,
@@ -385,7 +405,7 @@ static int setup_memcaches(struct sss_nss_ctx *nctx)
     }
 
     ret = sss_mmap_cache_init(nctx, "initgroups",
-                              nctx->mc_uid, nctx->mc_gid,
+                              uid, gid,
                               SSS_MC_INITGROUPS,
                               mc_size_initgroups * SSS_MC_CACHE_SLOTS_PER_MB,
                               (time_t)memcache_timeout,
@@ -397,7 +417,7 @@ static int setup_memcaches(struct sss_nss_ctx *nctx)
     }
 
     ret = sss_mmap_cache_init(nctx, "sid",
-                              nctx->mc_uid, nctx->mc_gid,
+                              uid, gid,
                               SSS_MC_SID,
                               mc_size_sid * SSS_MC_CACHE_SLOTS_PER_MB,
                               (time_t)memcache_timeout,
@@ -441,79 +461,6 @@ sss_nss_register_service_iface(struct sss_nss_ctx *nss_ctx,
     return ret;
 }
 
-static int sssd_supplementary_group(struct sss_nss_ctx *nss_ctx)
-{
-    errno_t ret;
-    int size;
-    gid_t *supp_gids = NULL;
-
-    /*
-     * We explicitly read the IDs of the SSSD user even though the server
-     * receives --uid and --gid by parameters to account for the case where
-     * the SSSD is compiled --with-sssd-user=sssd but the default of the
-     * user option is root (this is what RHEL does)
-     */
-    ret = sss_user_by_name_or_uid(SSSD_USER,
-                                  &nss_ctx->mc_uid,
-                                  &nss_ctx->mc_gid);
-    if (ret != EOK) {
-        DEBUG(SSSDBG_MINOR_FAILURE, "Cannot get info on "SSSD_USER);
-        return ret;
-    }
-
-    if (getgid() == nss_ctx->mc_gid) {
-        DEBUG(SSSDBG_TRACE_FUNC, "Already running as the sssd group\n");
-        return EOK;
-    }
-
-    size = getgroups(0, NULL);
-    if (size == -1) {
-        ret = errno;
-        DEBUG(SSSDBG_CRIT_FAILURE, "Getgroups failed! (%d, %s)\n",
-                                    ret, sss_strerror(ret));
-        return ret;
-    }
-
-    if (size > 0) {
-        supp_gids = talloc_zero_array(NULL, gid_t, size);
-        if (supp_gids == NULL) {
-            DEBUG(SSSDBG_CRIT_FAILURE, "Allocation failed!\n");
-            ret = ENOMEM;
-            goto done;
-        }
-
-        size = getgroups(size, supp_gids);
-        if (size == -1) {
-            ret = errno;
-            DEBUG(SSSDBG_CRIT_FAILURE, "Getgroups failed! (%d, %s)\n",
-                                        ret, sss_strerror(ret));
-            goto done;
-        }
-
-        for (int i = 0; i < size; i++) {
-            if (supp_gids[i] == nss_ctx->mc_gid) {
-                DEBUG(SSSDBG_TRACE_FUNC,
-                      "Already assigned to the SSSD supplementary group\n");
-                ret = EOK;
-                goto done;
-            }
-        }
-    }
-
-    ret = setgroups(1, &nss_ctx->mc_gid);
-    if (ret != EOK) {
-        ret = errno;
-        DEBUG(SSSDBG_OP_FAILURE,
-              "Cannot setgroups [%d]: %s\n", ret, sss_strerror(ret));
-        goto done;
-    }
-
-    ret = EOK;
-done:
-    talloc_free(supp_gids);
-    return ret;
-}
-
 int sss_nss_process_init(TALLOC_CTX *mem_ctx,
                          struct tevent_context *ev,
                          struct confdb_ctx *cdb)
@@ -613,19 +560,6 @@ int sss_nss_process_init(TALLOC_CTX *mem_ctx,
         goto fail;
     }
 
-    /*
-     * Adding the NSS process to the SSSD supplementary group avoids
-     * dac_override AVC messages from SELinux in case sssd_nss runs
-     * as root and tries to write to memcache owned by sssd:sssd
-     */
-    ret = sssd_supplementary_group(nctx);
-    if (ret != EOK) {
-        DEBUG(SSSDBG_MINOR_FAILURE,
-              "Cannot add process to the sssd supplementary group [%d]: %s\n",
-              ret, sss_strerror(ret));
-        goto fail;
-    }
-
     ret = setup_memcaches(nctx);
     if (ret != EOK) {
         goto fail;

src/responder/nss/nsssrv_mmap_cache.c

@@ -1271,6 +1271,7 @@ static errno_t sss_mc_create_file(struct sss_mc_ctx *mc_ctx)
         return ret;
     }
 
+#ifdef SSSD_NON_ROOT_USER
     /* Make sure that the memory cache files are chowned to sssd.sssd even
      * if the nss responder runs as root. This is because the specfile
      * has the ownership recorded as sssd.sssd
@@ -1284,6 +1285,7 @@ static errno_t sss_mc_create_file(struct sss_mc_ctx *mc_ctx)
             return ret;
         }
     }
+#endif /* SSSD_NON_ROOT_USER */
 
     ret = sss_br_lock_file(mc_ctx->fd, 0, 1, retries, t);
     if (ret != EOK) {