The '-i' commandline parameter to specify interface names no longer is mandatory. Specifying interface 'none' or sending a 'none' interface string within the ALFRED_CHANGE_INTERFACE unix socket command disables all interfaces operations at runtime. Signed-off-by: Marek Lindner &lt;mareklindner(a)neomailbox.ch&gt; --- README.rst | 6 +++++- alfred.h | 2 +- client.c | 8 ++++---- main.c | 6 +++--- man/alfred.8 | 6 +++++- netsock.c | 4 ++++ server.c | 39 ++++++++++++++++++++++++--------------- 7 files changed, 46 insertions(+), 25 deletions(-) diff --git a/README.rst b/README.rst index 33200e4..7f44db6 100644 --- a/README.rst +++ b/README.rst @@ -82,7 +82,8 @@ documentation how to configure alfred in this case. In any event, you can still run alfred from the command line. The relevant options are (for a full list of options, run alfred -h): - -i, --interface specify the interface to listen on + -i, --interface specify the interface to listen on. use 'none' + to disable interface operations -b specify the batman-adv interface configured on the system (default: bat0). use 'none' to disable the batman-adv based best server selection @@ -90,6 +91,9 @@ list of options, run alfred -h): accepts data from secondaries and syncs it with other primaries +The interface option '-i' is optional. If interface 'none' is specified, the +alfred daemon will not communicate with other alfred instances on the +network unless the interface list is modified at runtime via the unix socket. The -b option is optional, and only needed if you run alfred on a batman-adv interface not called bat0, or if you don't use batman-adv at all (use '-b none'). In this case, alfred will still work but will not be able to diff --git a/alfred.h b/alfred.h index c595b06..9ab92a2 100644 --- a/alfred.h +++ b/alfred.h @@ -112,7 +112,7 @@ struct interface { struct globals { struct list_head interfaces; - char *change_interface; + char *net_iface; struct server *best_server; /* NULL if we are a server ourselves */ char *mesh_iface; enum opmode opmode; diff --git a/client.c b/client.c index d0d19fb..b5d8943 100644 --- a/client.c +++ b/client.c @@ -252,7 +252,7 @@ int alfred_client_change_interface(struct globals *globals) if (unix_sock_open_client(globals)) return -1; - interface_len = strlen(globals->change_interface); + interface_len = strlen(globals->net_iface); if (interface_len > sizeof(change_interface.ifaces)) { fprintf(stderr, "%s: interface name list too long, not changing\n", __func__); @@ -264,15 +264,15 @@ int alfred_client_change_interface(struct globals *globals) change_interface.header.type = ALFRED_CHANGE_INTERFACE; change_interface.header.version = ALFRED_VERSION; change_interface.header.length = FIXED_TLV_LEN(change_interface); - strncpy(change_interface.ifaces, globals->change_interface, + strncpy(change_interface.ifaces, globals->net_iface, sizeof(change_interface.ifaces)); change_interface.ifaces[sizeof(change_interface.ifaces) - 1] = '\0'; /* test it before sending - * globals->change_interface is now saved in change_interface.ifaces + * globals->net_iface is now saved in change_interface.ifaces * and can be modified by strtok_r */ - input = globals->change_interface; + input = globals->net_iface; while ((token = strtok_r(input, ",", &saveptr))) { input = NULL; diff --git a/main.c b/main.c index 2cb6d44..d40a0cc 100644 --- a/main.c +++ b/main.c @@ -179,7 +179,7 @@ static struct globals *alfred_init(int argc, char *argv[]) memset(globals, 0, sizeof(*globals)); INIT_LIST_HEAD(&globals->interfaces); - globals->change_interface = NULL; + globals->net_iface = NULL; globals->opmode = OPMODE_SECONDARY; globals->clientmode = CLIENT_NONE; globals->best_server = NULL; @@ -224,7 +224,7 @@ static struct globals *alfred_init(int argc, char *argv[]) globals->opmode = OPMODE_PRIMARY; break; case 'i': - netsock_set_interfaces(globals, optarg); + globals->net_iface = strdup(optarg); break; case 'b': globals->mesh_iface = strdup(optarg); @@ -252,7 +252,7 @@ static struct globals *alfred_init(int argc, char *argv[]) break; case 'I': globals->clientmode = CLIENT_CHANGE_INTERFACE; - globals->change_interface = strdup(optarg); + globals->net_iface = strdup(optarg); break; case 'B': globals->clientmode = CLIENT_CHANGE_BAT_IFACE; diff --git a/man/alfred.8 b/man/alfred.8 index 4e002f0..74814e0 100644 --- a/man/alfred.8 +++ b/man/alfred.8 @@ -98,12 +98,16 @@ Change the alfred server to use the new \fBbatman-adv interface\fP .SH SERVER OPTIONS .TP \fB\-i\fP, \fB\-\-interface\fP \fIiface\fP -Specify the interface (or comma separated list of interfaces) to listen on +Specify the interface (or comma separated list of interfaces) to listen on. +Use 'none' to disable interface operations. .TP \fB\-b\fP \fIbatmanif\fP Specify the batman-adv interface configured on the system (default: bat0). Use 'none' to disable the batman-adv based best server selection. +The interface option \fB\-i\fP is optional. If interface 'none' is specified, the +alfred daemon will not communicate with other alfred instances on the +network unless the interface list is modified at runtime via the unix socket. The \fB\-b\fP option is optional, and only needed if you run alfred on a batman-adv interface not called bat0, or if you don't use batman-adv at all (use '\fB\-b\fP none'). In this case, alfred will still work but will not be diff --git a/netsock.c b/netsock.c index 84b0ec3..128e768 100644 --- a/netsock.c +++ b/netsock.c @@ -116,6 +116,10 @@ int netsock_set_interfaces(struct globals *globals, char *interfaces) netsock_close_all(globals); + /* interface 'none' disables all interface operations */ + if (is_iface_disabled(interfaces)) + return 0; + input = interfaces; while ((token = strtok_r(input, ",", &saveptr))) { input = NULL; diff --git a/server.c b/server.c index 1efc211..bfc37bc 100644 --- a/server.c +++ b/server.c @@ -380,9 +380,30 @@ int alfred_server(struct globals *globals) if (unix_sock_open_daemon(globals)) return -1; - if (list_empty(&globals->interfaces)) { - fprintf(stderr, "Can't start server: interface missing\n"); - return -1; + if (!is_iface_disabled(globals->net_iface)) { + if (!globals->net_iface) { + fprintf(stderr, "Can't start server: interface missing\n"); + return -1; + } + + netsock_set_interfaces(globals, globals->net_iface); + + if (list_empty(&globals->interfaces) && !globals->force) { + fprintf(stderr, "Can't start server: valid interface missing\n"); + return -1; + } + + num_socks = netsock_open_all(globals); + if (num_socks <= 0 && !globals->force) { + fprintf(stderr, "Failed to open interfaces\n"); + return -1; + } + + num_interfaces = netsocket_count_interfaces(globals); + if (num_interfaces > 1 && globals->opmode == OPMODE_SECONDARY) { + fprintf(stderr, "More than one interface specified in secondary mode\n"); + return -1; + } } if (!is_iface_disabled(globals->mesh_iface) && @@ -393,18 +414,6 @@ int alfred_server(struct globals *globals) return -1; } - num_socks = netsock_open_all(globals); - if (num_socks <= 0 && !globals->force) { - fprintf(stderr, "Failed to open interfaces\n"); - return -1; - } - - num_interfaces = netsocket_count_interfaces(globals); - if (num_interfaces > 1 && globals->opmode == OPMODE_SECONDARY) { - fprintf(stderr, "More than one interface specified in secondary mode\n"); - return -1; - } - clock_gettime(CLOCK_MONOTONIC, &last_check); globals->if_check = last_check; -- 2.32.0.rc0

On Friday, 21 January 2022 16:34:50 CET Sven Eckelmann wrote: The struct alfred_change_interface_v0 -> ifaces[IFNAMSIZ * 16] may be written to but not fully initialized. The interface name may be much shorter than the buffer holding it. Same applies struct alfred_change_bat_iface_v0 -> bat_iface[IFNAMSIZ] but to a lesser extent because the buffer is smaller. This patch is based on your earlier observation that stack data may be leaked due to the lack of (complete) initialization. You are correct that the structs struct alfred_request_v0 & alfred_modeswitch_v0 technically don't require initialization because all fields are set manually. I added those for completeness sake for the next person coming along copy & pasting the code (as I had done). Kind regards, Marek Lindner