diff options
| author | Ishan Agrawal <iagrawal9990@gmail.com> | 2026-06-29 05:17:14 +0000 |
|---|---|---|
| committer | Kristof Provost <kp@FreeBSD.org> | 2026-07-05 14:03:34 +0000 |
| commit | 80586e853674c6d63888379274accea5c82407f2 (patch) | |
| tree | 5e2f446119578b3a68bf690995394578965fac11 | |
| parent | 8a1576dc26b90706948061e5ed33f07a03a5899c (diff) | |
libsysdecode: decode Generic Netlink controller messages
Decode Generic Netlink controller (GENL_ID_CTRL) messages in
Netlink payloads. Display the Generic Netlink header along with
the CTRL_CMD_GETFAMILY attributes, including the family ID and
family name.
Signed-off-by: Ishan Agrawal <iagrawal9990@gmail.com>
Reviewed by: kp
Sponsored-by: Google LLC (GSoC 2026)
| -rw-r--r-- | lib/libsysdecode/netlink.c | 70 |
1 files changed, 60 insertions, 10 deletions
diff --git a/lib/libsysdecode/netlink.c b/lib/libsysdecode/netlink.c index 723272d3b8da..4dbe6c087dcf 100644 --- a/lib/libsysdecode/netlink.c +++ b/lib/libsysdecode/netlink.c @@ -6,6 +6,8 @@ #include <sys/param.h> #include <netlink/netlink.h> +#include <netlink/netlink_generic.h> +#include <netlink/netlink_snl.h> #include <stdio.h> #include <stdbool.h> @@ -20,6 +22,7 @@ * Returns false if the data is malformed, allowing the caller * to fallback to a standard hex/string dump. */ + bool sysdecode_netlink(FILE *fp, const void *buf, size_t len, int protocol) { @@ -51,7 +54,16 @@ sysdecode_netlink(FILE *fp, const void *buf, size_t len, int protocol) break; } - fprintf(fp, "len=%u,type=", nl->nlmsg_len); + fprintf(fp, "flags="); + const char *nlm_f = sysdecode_nlm_flag(nl->nlmsg_flags); + if (nlm_f != NULL) + fprintf(fp, "%s", nlm_f); + else + fprintf(fp, "0x%x", nl->nlmsg_flags); + + fprintf(fp, ",seq=%u,pid=%u", nl->nlmsg_seq, nl->nlmsg_pid); + + fprintf(fp, ",len=%u,type=", nl->nlmsg_len); /* Decode Standard Message Types. */ switch (nl->nlmsg_type) { @@ -67,20 +79,58 @@ sysdecode_netlink(FILE *fp, const void *buf, size_t len, int protocol) case NLMSG_OVERRUN: fprintf(fp, "NLMSG_OVERRUN"); break; + case GENL_ID_CTRL: + if (protocol != NETLINK_GENERIC) + break; + + fprintf(fp, "GENL_ID_CTRL"); + + const struct genlmsghdr *genl = + (const struct genlmsghdr *)(const void *) + ((const char *)nl + sizeof(struct nlmsghdr)); + + uint16_t family_id = 0; + const char *family_name = NULL; + + fprintf(fp, + ",genl={cmd=%u," + "ver=%u,reserve=%u", + genl->cmd, + genl->version, genl->reserved); + + size_t cur_len = (sizeof(struct nlmsghdr) + + sizeof(struct genlmsghdr)); + size_t nla_len = nl->nlmsg_len - cur_len; + + const struct nlattr *nla; + const struct nlattr *nla_head = (const struct nlattr *) + (const void *)((const char *)nl + cur_len); + + NLA_FOREACH_CONST(nla, nla_head, nla_len) { + switch (nla->nla_type) { + case CTRL_ATTR_FAMILY_ID: + memcpy(&family_id, NLA_DATA_CONST(nla), + sizeof(family_id)); + fprintf(fp, ",family_id=%u", family_id); + break; + case CTRL_ATTR_FAMILY_NAME: + family_name = + ((const char *)NLA_DATA_CONST(nla)); + fprintf(fp, ",family_name=%s", + family_name); + break; + default: + break; + } + } + + fprintf(fp, "}"); + break; default: fprintf(fp, "%u", nl->nlmsg_type); break; } - fprintf(fp, ",flags="); - const char *nlm_f = sysdecode_nlm_flag(nl->nlmsg_flags); - if (nlm_f != NULL) - fprintf(fp, "%s", nlm_f); - else - fprintf(fp, "0x%x", nl->nlmsg_flags); - - fprintf(fp, ",seq=%u,pid=%u", nl->nlmsg_seq, nl->nlmsg_pid); - /* Handle Alignment (Netlink messages are 4-byte aligned). */ size_t aligned_len = NLMSG_ALIGN(nl->nlmsg_len); if (aligned_len > remaining) |