Add support for setting the group on a unix domain socket (#901)

Add new optional, immutable string config called `unixsocketgroup`. 
Change the group of the unix socket to `unixsocketgroup` after `bind()`
if specified.

Adds tests to validate the behavior.

Fixes #873.

Signed-off-by: Ayush Sharma <[email protected]>

src/anet.c

@@ -45,6 +45,7 @@
 #include <errno.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <grp.h>
 
 #include "anet.h"
 #include "config.h"
@@ -505,7 +506,7 @@ int anetTcpNonBlockBestEffortBindConnect(char *err, const char *addr, int port,
     return anetTcpGenericConnect(err, addr, port, source_addr, ANET_CONNECT_NONBLOCK | ANET_CONNECT_BE_BINDING);
 }
 
-static int anetListen(char *err, int s, struct sockaddr *sa, socklen_t len, int backlog, mode_t perm) {
+static int anetListen(char *err, int s, struct sockaddr *sa, socklen_t len, int backlog, mode_t perm, char *group) {
     if (bind(s, sa, len) == -1) {
         anetSetError(err, "bind: %s", strerror(errno));
         close(s);
@@ -514,6 +515,22 @@ static int anetListen(char *err, int s, struct sockaddr *sa, socklen_t len, int
 
     if (sa->sa_family == AF_LOCAL && perm) chmod(((struct sockaddr_un *)sa)->sun_path, perm);
 
+    if (sa->sa_family == AF_LOCAL && group != NULL) {
+        struct group *grp;
+        if ((grp = getgrnam(group)) == NULL) {
+            anetSetError(err, "getgrnam error for group '%s': %s", group, strerror(errno));
+            close(s);
+            return ANET_ERR;
+        }
+
+        /* Owner of the socket remains same. */
+        if (chown(((struct sockaddr_un *)sa)->sun_path, -1, grp->gr_gid) == -1) {
+            anetSetError(err, "chown error for group '%s': %s", group, strerror(errno));
+            close(s);
+            return ANET_ERR;
+        }
+    }
+
     if (listen(s, backlog) == -1) {
         anetSetError(err, "listen: %s", strerror(errno));
         close(s);
@@ -553,7 +570,7 @@ static int _anetTcpServer(char *err, int port, char *bindaddr, int af, int backl
 
         if (af == AF_INET6 && anetV6Only(err, s) == ANET_ERR) goto error;
         if (anetSetReuseAddr(err, s) == ANET_ERR) goto error;
-        if (anetListen(err, s, p->ai_addr, p->ai_addrlen, backlog, 0) == ANET_ERR) s = ANET_ERR;
+        if (anetListen(err, s, p->ai_addr, p->ai_addrlen, backlog, 0, NULL) == ANET_ERR) s = ANET_ERR;
         goto end;
     }
     if (p == NULL) {
@@ -577,7 +594,7 @@ int anetTcp6Server(char *err, int port, char *bindaddr, int backlog) {
     return _anetTcpServer(err, port, bindaddr, AF_INET6, backlog);
 }
 
-int anetUnixServer(char *err, char *path, mode_t perm, int backlog) {
+int anetUnixServer(char *err, char *path, mode_t perm, int backlog, char *group) {
     int s;
     struct sockaddr_un sa;
 
@@ -593,7 +610,7 @@ int anetUnixServer(char *err, char *path, mode_t perm, int backlog) {
     memset(&sa, 0, sizeof(sa));
     sa.sun_family = AF_LOCAL;
     valkey_strlcpy(sa.sun_path, path, sizeof(sa.sun_path));
-    if (anetListen(err, s, (struct sockaddr *)&sa, sizeof(sa), backlog, perm) == ANET_ERR) return ANET_ERR;
+    if (anetListen(err, s, (struct sockaddr *)&sa, sizeof(sa), backlog, perm, group) == ANET_ERR) return ANET_ERR;
     return s;
 }
 

src/anet.h

@@ -56,7 +56,7 @@ int anetTcpNonBlockBestEffortBindConnect(char *err, const char *addr, int port,
 int anetResolve(char *err, char *host, char *ipbuf, size_t ipbuf_len, int flags);
 int anetTcpServer(char *err, int port, char *bindaddr, int backlog);
 int anetTcp6Server(char *err, int port, char *bindaddr, int backlog);
-int anetUnixServer(char *err, char *path, mode_t perm, int backlog);
+int anetUnixServer(char *err, char *path, mode_t perm, int backlog, char *group);
 int anetTcpAccept(char *err, int serversock, char *ip, size_t ip_len, int *port);
 int anetUnixAccept(char *err, int serversock);
 int anetNonBlock(char *err, int fd);

src/config.c

@@ -3110,6 +3110,7 @@ standardConfig static_configs[] = {
     /* String Configs */
     createStringConfig("aclfile", NULL, IMMUTABLE_CONFIG, ALLOW_EMPTY_STRING, server.acl_filename, "", NULL, NULL),
     createStringConfig("unixsocket", NULL, IMMUTABLE_CONFIG, EMPTY_STRING_IS_NULL, server.unixsocket, NULL, NULL, NULL),
+    createStringConfig("unixsocketgroup", NULL, IMMUTABLE_CONFIG, EMPTY_STRING_IS_NULL, server.unixsocketgroup, NULL, NULL, NULL),
     createStringConfig("pidfile", NULL, IMMUTABLE_CONFIG, EMPTY_STRING_IS_NULL, server.pidfile, NULL, NULL, NULL),
     createStringConfig("replica-announce-ip", "slave-announce-ip", MODIFIABLE_CONFIG, EMPTY_STRING_IS_NULL, server.replica_announce_ip, NULL, NULL, NULL),
     createStringConfig("primaryuser", "masteruser", MODIFIABLE_CONFIG | SENSITIVE_CONFIG, EMPTY_STRING_IS_NULL, server.primary_user, NULL, NULL, NULL),

src/connection.h

@@ -144,7 +144,8 @@ struct connListener {
     int bindaddr_count;
     int port;
     ConnectionType *ct;
-    void *priv; /* used by connection type specified data */
+    void *priv1; /* used by connection type specified data */
+    void *priv2; /* used by connection type specified data */
 };
 
 /* The connection module does not deal with listening and accepting sockets,

src/rdma.c

@@ -748,7 +748,7 @@ static rdma_listener *rdmaFdToListener(connListener *listener, int fd) {
     for (int i = 0; i < listener->count; i++) {
         if (listener->fd[i] != fd) continue;
 
-        return (rdma_listener *)listener->priv + i;
+        return (rdma_listener *)listener->priv1 + i;
     }
 
     return NULL;
@@ -1517,7 +1517,7 @@ int connRdmaListen(connListener *listener) {
         bindaddr = default_bindaddr;
     }
 
-    listener->priv = rdma_listener = zcalloc_num(bindaddr_count, sizeof(*rdma_listener));
+    listener->priv1 = rdma_listener = zcalloc_num(bindaddr_count, sizeof(*rdma_listener));
     for (j = 0; j < bindaddr_count; j++) {
         char *addr = bindaddr[j];
         int optional = *addr == '-';
@@ -1736,13 +1736,13 @@ static int rdmaChangeListener(void) {
 
         aeDeleteFileEvent(server.el, listener->fd[i], AE_READABLE);
         listener->fd[i] = -1;
-        struct rdma_listener *rdma_listener = (struct rdma_listener *)listener->priv + i;
+        struct rdma_listener *rdma_listener = (struct rdma_listener *)listener->priv1 + i;
         rdma_destroy_id(rdma_listener->cm_id);
         rdma_destroy_event_channel(rdma_listener->cm_channel);
     }
 
     listener->count = 0;
-    zfree(listener->priv);
+    zfree(listener->priv1);
 
     closeListener(listener);
 

src/server.c

@@ -2787,7 +2787,8 @@ void initListeners(void) {
         listener->bindaddr = &server.unixsocket;
         listener->bindaddr_count = 1;
         listener->ct = connectionByType(CONN_TYPE_UNIX);
-        listener->priv = &server.unixsocketperm; /* Unix socket specified */
+        listener->priv1 = &server.unixsocketperm; /* Unix socket specified */
+        listener->priv2 = server.unixsocketgroup; /* Unix socket group specified */
     }
 
     /* create all the configured listener, and add handler to start to accept */

src/server.h

@@ -1712,6 +1712,7 @@ struct valkeyServer {
     int bindaddr_count;                    /* Number of addresses in server.bindaddr[] */
     char *bind_source_addr;                /* Source address to bind on for outgoing connections */
     char *unixsocket;                      /* UNIX socket path */
+    char *unixsocketgroup;                 /* UNIX socket group */
     unsigned int unixsocketperm;           /* UNIX socket permission (see mode_t) */
     connListener listeners[CONN_TYPE_MAX]; /* TCP/Unix/TLS even more types */
     uint32_t socket_mark_id;               /* ID for listen socket marking */

src/unix.c

@@ -51,7 +51,8 @@ static int connUnixIsLocal(connection *conn) {
 
 static int connUnixListen(connListener *listener) {
     int fd;
-    mode_t *perm = (mode_t *)listener->priv;
+    mode_t *perm = (mode_t *)listener->priv1;
+    char *group = (char *)listener->priv2;
 
     if (listener->bindaddr_count == 0) return C_OK;
 
@@ -61,7 +62,7 @@ static int connUnixListen(connListener *listener) {
         char *addr = listener->bindaddr[j];
 
         unlink(addr); /* don't care if this fails */
-        fd = anetUnixServer(server.neterr, addr, *perm, server.tcp_backlog);
+        fd = anetUnixServer(server.neterr, addr, *perm, server.tcp_backlog, group);
         if (fd == ANET_ERR) {
             serverLog(LL_WARNING, "Failed opening Unix socket: %s", server.neterr);
             exit(1);

tests/unit/introspection.tcl

@@ -533,6 +533,7 @@ start_server {tags {"introspection"}} {
             io-threads
             logfile
             unixsocketperm
+            unixsocketgroup
             replicaof
             slaveof
             requirepass

tests/unit/other.tcl

@@ -544,3 +544,26 @@ start_server {tags {"other external:skip"}} {
         }   
     }
 }
+
+set tempFileName [file join [pwd] [pid]]
+if {$::verbose} {
+    puts "Creating temp file $tempFileName"
+}
+set tempFileId [open $tempFileName w]
+set group [dict get [file attributes $tempFileName] -group]
+if {$group != ""} {
+    start_server [list tags {"repl external:skip"} overrides [list unixsocketgroup $group unixsocketperm 744]] {
+        test {test unixsocket options are set correctly} {
+            set socketpath [lindex [r config get unixsocket] 1]
+            set attributes [file attributes $socketpath]
+            set permissions [string range [dict get $attributes -permissions] end-2 end]
+            assert_equal [dict get $attributes -group] $group
+            assert_equal 744 $permissions
+        }
+    }
+}
+if {$::verbose} {
+    puts "Deleting temp file: $tempFileName"
+}
+close $tempFileId
+file delete $tempFileName

valkey.conf

@@ -154,6 +154,7 @@ tcp-backlog 511
 # on a unix socket when not specified.
 #
 # unixsocket /run/valkey.sock
+# unixsocketgroup wheel
 # unixsocketperm 700
 
 # Close the connection after a client is idle for N seconds (0 to disable)