iw: add support for retrieving keys

For debugging purposes, it can be useful to be able to retrieve keys.

Add a "iw key get" command, to be able to retrieve keys when the key
index is known. A new "key" section is also introduced, in preparation
for future key-related commands.

Example retrieving a pairwise key:
iw dev wlan0 key get 0 02:02:03:04:05:06

Example retrieving a group key:
iw dev wlan0 key get 1

Note that only the outer ATTR_KEY_DATA (and seq) is reported, the
nested KEY_DATA (and seq) within ATTR_KEY is not.

Signed-off-by: Raphaël Mélotte <raphael.melotte@mind.be>
Link: https://lore.kernel.org/r/20230112122525.2257298-1-raphael.melotte@mind.be
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/keys.c b/keys.c
new file mode 100644 (file)
index 0000000..65aa426
--- /dev/null
+++ b/keys.c
@@ -0,0 +1,83 @@
+#include <errno.h>
+#include <netlink/genl/genl.h>
+#include <netlink/genl/family.h>
+#include <netlink/genl/ctrl.h>
+#include <netlink/msg.h>
+#include <netlink/attr.h>
+#include "nl80211.h"
+#include "iw.h"
+
+SECTION(key);
+
+static int print_keys(struct nl_msg *msg, void *arg)
+{
+       struct genlmsghdr *gnlh = nlmsg_data(nlmsg_hdr(msg));
+       struct nlattr *tb[NL80211_ATTR_MAX + 1];
+
+       nla_parse(tb, NL80211_ATTR_MAX, genlmsg_attrdata(gnlh, 0),
+                 genlmsg_attrlen(gnlh, 0), NULL);
+
+       if (!tb[NL80211_ATTR_KEY_IDX]) {
+               fprintf(stderr, "KEY_IDX missing!\n");
+               return NL_SKIP;
+       }
+
+       if (!tb[NL80211_ATTR_KEY_DATA]) {
+               fprintf(stderr, "ATTR_KEY_DATA missing!\n");
+               return NL_SKIP;
+       }
+
+       iw_hexdump("Key", nla_data(tb[NL80211_ATTR_KEY_DATA]),
+                  nla_len(tb[NL80211_ATTR_KEY_DATA]));
+
+       if (!tb[NL80211_ATTR_KEY_SEQ]) {
+               fprintf(stderr, "ATTR_KEY_SEQ missing!\n");
+               return NL_SKIP;
+       }
+
+       iw_hexdump("Key seq", nla_data(tb[NL80211_ATTR_KEY_SEQ]),
+                  nla_len(tb[NL80211_ATTR_KEY_SEQ]));
+
+       return NL_OK;
+}
+
+static int handle_get_key(struct nl80211_state *state,
+                         struct nl_msg *msg, int argc, char **argv,
+                         enum id_input id)
+{
+       char *end;
+       unsigned char mac[6];
+
+       /* key index */
+       if (argc) {
+               nla_put_u8(msg, NL80211_ATTR_KEY_IDX, strtoul(argv[0], &end, 10));
+               if (*end != '\0')
+                       return -EINVAL;
+               argv++;
+               argc--;
+       }
+
+       /* mac */
+       if (argc) {
+               if (mac_addr_a2n(mac, argv[0]) == 0) {
+                       NLA_PUT(msg, NL80211_ATTR_MAC, 6, mac);
+                       nla_put_u32(msg, NL80211_ATTR_KEY_TYPE,
+                                   NL80211_KEYTYPE_PAIRWISE);
+                       argv++;
+                       argc--;
+               } else {
+                       return -EINVAL;
+               }
+       } else {
+               nla_put_u32(msg, NL80211_ATTR_KEY_TYPE, NL80211_KEYTYPE_GROUP);
+       }
+
+       register_handler(print_keys, NULL);
+       return 0;
+
+ nla_put_failure:
+       return -ENOSPC;
+}
+COMMAND(key, get, "<key index> <MAC address>",
+       NL80211_CMD_GET_KEY, 0, CIB_NETDEV, handle_get_key,
+       "Retrieve a key and key sequence.\n");