src/libsystemd/sd-netlink/generic-netlink.c

   1 #include <linux/genetlink.h>
   2
   3 #include "sd-netlink.h"
   4 #include "netlink-internal.h"
   5 #include "alloc-util.h"
   6
   7 typedef struct {
   8         const char* name;
   9         uint8_t version;
  10 } genl_family;
  11
  12 static const genl_family genl_families[] = {
  13         [SD_GENL_ID_CTRL] = { .name = "", .version = 1 },
  14         [SD_GENL_WIREGUARD] = { .name = "wireguard", .version = 1 },
  15 };
  16
  17 int sd_genl_socket_open(sd_netlink **ret) {
  18         return netlink_open_family(ret, NETLINK_GENERIC);
  19 }
  20 static int lookup_id(sd_netlink *nl, sd_genl_family family, uint16_t *id);
  21
  22 static int genl_message_new(sd_netlink *nl, sd_genl_family family, uint16_t nlmsg_type, uint8_t cmd, sd_netlink_message **ret) {
  23         int r;
  24         struct genlmsghdr *genl;
  25         const NLType *genl_cmd_type, *nl_type;
  26         const NLTypeSystem *type_system;
  27         size_t size;
  28         _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;
  29
  30         assert_return(nl->protocol == NETLINK_GENERIC, -EINVAL);
  31
  32         r = type_system_get_type(&genl_family_type_system_root, &genl_cmd_type, family);
  33         if (r < 0)
  34                 return r;
  35
  36         r = message_new_empty(nl, &m);
  37         if (r < 0)
  38                 return r;
  39
  40         size = NLMSG_SPACE(sizeof(struct genlmsghdr));
  41         m->hdr = malloc0(size);
  42         if (!m->hdr)
  43                 return -ENOMEM;
  44
  45         m->hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
  46
  47         type_get_type_system(genl_cmd_type, &type_system);
  48
  49         r = type_system_get_type(type_system, &nl_type, cmd);
  50         if (r < 0)
  51                 return r;
  52
  53         m->hdr->nlmsg_len = size;
  54         m->hdr->nlmsg_type = nlmsg_type;
  55
  56         type_get_type_system(nl_type, &m->containers[0].type_system);
  57         genl = NLMSG_DATA(m->hdr);
  58         genl->cmd = cmd;
  59         genl->version = genl_families[family].version;
  60
  61         *ret = m;
  62         m = NULL;
  63
  64         return 0;
  65 }
  66
  67 int sd_genl_message_new(sd_netlink *nl, sd_genl_family family, uint8_t cmd, sd_netlink_message **ret) {
  68         int r;
  69         uint16_t id = GENL_ID_CTRL;
  70
  71         if (family != SD_GENL_ID_CTRL) {
  72                 r = lookup_id(nl, family, &id);
  73                 if (r < 0)
  74                         return r;
  75         }
  76
  77         return genl_message_new(nl, family, id, cmd, ret);
  78 }
  79
  80 static int lookup_id(sd_netlink *nl, sd_genl_family family, uint16_t *id) {
  81         int r;
  82         _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *req = NULL, *reply = NULL;
  83
  84         r = sd_genl_message_new(nl, SD_GENL_ID_CTRL, CTRL_CMD_GETFAMILY, &req);
  85         if (r < 0)
  86                 return r;
  87
  88         r = sd_netlink_message_append_string(req, CTRL_ATTR_FAMILY_NAME, genl_families[family].name);
  89         if (r < 0)
  90                 return r;
  91
  92         r = sd_netlink_call(nl, req, 0, &reply);
  93         if (r < 0)
  94                 return r;
  95
  96         return sd_netlink_message_read_u16(reply, CTRL_ATTR_FAMILY_ID, id);
  97 }