Date: Fri, 24 Jul 2026 15:04:08 +0000 From: Kristof Provost <kp@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Cc: Ishan Agrawal <iagrawal9990@gmail.com> Subject: git: 26bb78b77231 - main - libsysdecode: add Netlink attribute decoding infrastructure Message-ID: <6a637ee8.3620a.6a13d1a8@gitrepo.freebsd.org>
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The branch main has been updated by kp: URL: https://cgit.FreeBSD.org/src/commit/?id=26bb78b77231c4b2d80f7d89f39e9e06294151d2 commit 26bb78b77231c4b2d80f7d89f39e9e06294151d2 Author: Ishan Agrawal <iagrawal9990@gmail.com> AuthorDate: 2026-07-22 15:31:23 +0000 Commit: Kristof Provost <kp@FreeBSD.org> CommitDate: 2026-07-24 15:02:37 +0000 libsysdecode: add Netlink attribute decoding infrastructure Introduce a generic Netlink attribute decoding framework based on attribute decoder tables. The framework supports decoding primitive attribute types as well as nested attributes and can be reused by different Generic Netlink families. Signed-off-by: Ishan Agrawal <iagrawal9990@gmail.com> Sponsored-by: Google LLC (GSoC 2026) Reviewed-by: kp Pull-Request: https://github.com/freebsd/freebsd-src/pull/2337 --- lib/libsysdecode/netlink.c | 215 ++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 213 insertions(+), 2 deletions(-) diff --git a/lib/libsysdecode/netlink.c b/lib/libsysdecode/netlink.c index ce8ac0485009..bb07ad2e4bf7 100644 --- a/lib/libsysdecode/netlink.c +++ b/lib/libsysdecode/netlink.c @@ -5,9 +5,14 @@ */ #include <sys/param.h> +#include <sys/types.h> +#include <sys/socket.h> +#include <netinet/in.h> +#include <arpa/inet.h> #include <netlink/netlink.h> #include <netlink/netlink_generic.h> #include <netlink/netlink_snl.h> +#include <netpfil/pf/pf_nl.h> #include <stdio.h> #include <stdbool.h> @@ -29,8 +34,195 @@ static struct name_table *family_table = NULL; static size_t num_family = 0; +typedef void decode_attr_f(FILE *fp, const struct nlattr *attr, + const char *attr_name, const void *args); +struct nlattr_decoder { + uint16_t type; /* Attribute type */ + const char *attr_name; /* Attribute name*/ + decode_attr_f *cb; /* decoder function to call */ + const void *args; /* nested decoder */ +}; + +struct nlattr_decoder_set { + const struct nlattr_decoder *decoders; /* PFNL CMD Decoders */ + size_t count; /*Attribute Count*/ +}; + +#define NL_DECLARE_ATTR_DECODER(_name, _np) \ +static const struct nlattr_decoder_set _name = { \ + .decoders = &((_np)[0]), \ + .count = nitems(_np), \ +} + +static void nl_decode_attrs_raw(FILE *fp, const struct nlattr *nla_head, + size_t len, const struct nlattr_decoder *ps, size_t pslen); + +static void +nlattr_decode_in6_addr(FILE *fp, const struct nlattr *attr, + const char *attr_name, const void *args) +{ + (void)args; + + struct in6_addr target; + + if (NLA_DATA_LEN(attr) < (int)sizeof(target)) + return; + + memcpy(&target, NLA_DATA_CONST(attr), sizeof(struct in6_addr)); + + fprintf(fp, "%s=", attr_name); + + char buf[INET6_ADDRSTRLEN]; + + if (inet_ntop(AF_INET6, &target, buf, sizeof(buf)) != NULL) + fprintf(fp, "%s", buf); +} + +static void +nlattr_decode_uint32(FILE *fp, const struct nlattr *attr, const char *attr_name, + const void *args) +{ + (void)args; + + uint32_t target; + + if (NLA_DATA_LEN(attr) < (int)sizeof(target)) + return; + + memcpy(&target, NLA_DATA_CONST(attr), sizeof(uint32_t)); + + fprintf(fp, "%s=%u", attr_name, target); +} + +static void +nlattr_decode_uint8(FILE *fp, const struct nlattr *attr, const char *attr_name, + const void *args) +{ + (void)args; + + uint8_t target; + + if (NLA_DATA_LEN(attr) < (int)sizeof(target)) + return; + + memcpy(&target, NLA_DATA_CONST(attr), sizeof(uint8_t)); + + fprintf(fp, "%s=%u", attr_name, target); +} + +static void +nlattr_decode_string(FILE *fp, const struct nlattr *attr, const char *attr_name, + const void *args) +{ + (void)args; + + if (NLA_DATA_LEN(attr) == 0) + return; + + const char *target = (const char *)NLA_DATA_CONST(attr); + + fprintf(fp, "%s=%s", attr_name, target); +} + +static void +nlattr_decode_nested(FILE *fp, const struct nlattr *attr, const char *attr_name, + const void *args) +{ + const struct nlattr_decoder_set *set = args; + + if (set == NULL) + return; + + fprintf(fp, "%s=", attr_name); + + nl_decode_attrs_raw(fp, NLA_DATA_CONST(attr), NLA_DATA_LEN(attr), + set->decoders, set->count); +} + +static const struct nlattr_decoder * +search_decoders(const struct nlattr_decoder *ps, size_t pslen, int key) +{ + size_t left_i = 0, right_i = pslen - 1; + + if (pslen == 0) + return (NULL); + + if (key < ps[0].type || key > ps[pslen - 1].type) + return (NULL); + + while (left_i + 1 < right_i) { + size_t mid_i = (left_i + right_i) / 2; + if (key < ps[mid_i].type) + right_i = mid_i; + else if (key > ps[mid_i].type) + left_i = mid_i + 1; + else + return (&ps[mid_i]); + } + if (ps[left_i].type == key) + return (&ps[left_i]); + else if (ps[right_i].type == key) + return (&ps[right_i]); + return (NULL); +} + static void -sysdecode_netlink_pf(FILE *fp, const struct genlmsghdr *genl) +nl_decode_attrs_raw(FILE *fp, const struct nlattr *nla_head, size_t len, + const struct nlattr_decoder *ps, size_t pslen) +{ + const struct nlattr_decoder *s; + const struct nlattr *nla; + bool first = true; + + fprintf(fp, "{"); + + NLA_FOREACH_CONST(nla, nla_head, len) { + if (!first) + fprintf(fp, ","); + + s = search_decoders(ps, pslen, nla->nla_type & NLA_TYPE_MASK); + if (s != NULL && s->cb != NULL) + s->cb(fp, nla, s->attr_name, s->args); + + first = false; + } + + fprintf(fp, "}"); +} + +static const struct nlattr_decoder nla_d_addr_wrap[] = { + { .type = PF_AT_ADDR, .attr_name = "addr", .cb = nlattr_decode_in6_addr }, + { .type = PF_AT_MASK, .attr_name = "mask", .cb = nlattr_decode_in6_addr }, + { .type = PF_AT_IFNAME, .attr_name = "ifname", .cb = nlattr_decode_string }, + { .type = PF_AT_TABLENAME, .attr_name = "tablename", .cb = nlattr_decode_string }, + { .type = PF_AT_TYPE, .attr_name = "type", .cb = nlattr_decode_uint8 }, + { .type = PF_AT_IFLAGS, .attr_name = "iflags", .cb = nlattr_decode_uint8 }, +}; +NL_DECLARE_ATTR_DECODER(addr_wrap_decoder, nla_d_addr_wrap); + +static const struct nlattr_decoder nla_d_pool_addr[] = { + { .type = PF_PA_ADDR, .attr_name = "addr", .cb = nlattr_decode_nested, .args = &addr_wrap_decoder}, + { .type = PF_PA_IFNAME, .attr_name = "ifname", .cb = nlattr_decode_string }, +}; +NL_DECLARE_ATTR_DECODER(pool_addr_decoder, nla_d_pool_addr); + +static const struct nlattr_decoder nla_d_add_addr[] = { + { .type = PF_AA_ACTION, .attr_name = "action", .cb = nlattr_decode_uint32 }, + { .type = PF_AA_TICKET, .attr_name = "ticket", .cb = nlattr_decode_uint32 }, + { .type = PF_AA_NR, .attr_name = "nr", .cb = nlattr_decode_uint32 }, + { .type = PF_AA_R_NUM, .attr_name = "r_num", .cb = nlattr_decode_uint32 }, + { .type = PF_AA_R_ACTION, .attr_name = "r_action", .cb = nlattr_decode_uint8 }, + { .type = PF_AA_R_LAST, .attr_name = "r_last", .cb = nlattr_decode_uint8 }, + { .type = PF_AA_AF, .attr_name = "af", .cb = nlattr_decode_uint8 }, + { .type = PF_AA_ANCHOR, .attr_name = "anchor", .cb = nlattr_decode_string }, + { .type = PF_AA_ADDR, .attr_name = "addr", .cb = nlattr_decode_nested , .args = &pool_addr_decoder}, + { .type = PF_AA_WHICH, .attr_name = "which", .cb = nlattr_decode_uint32 }, +}; +NL_DECLARE_ATTR_DECODER(addr_parser, nla_d_add_addr); + + +static void +sysdecode_netlink_pf(FILE *fp, const struct genlmsghdr *genl, size_t nlm_len) { uint8_t cmd = genl->cmd; const char *cmd_name = sysdecode_pfnl_cmd(cmd); @@ -39,6 +231,22 @@ sysdecode_netlink_pf(FILE *fp, const struct genlmsghdr *genl) fprintf(fp, "cmd=%s", cmd_name); else fprintf(fp, "cmd=%u", cmd); + + const struct nlattr *nla = (const struct nlattr *)(const void *) + ((const char *)genl + sizeof(struct genlmsghdr)); + + switch (cmd) { + case PFNL_CMD_GET_ADDR: + nl_decode_attrs_raw(fp, nla, nlm_len, + addr_parser.decoders, addr_parser.count); + break; + case PFNL_CMD_GET_ADDRS: + nl_decode_attrs_raw(fp, nla, nlm_len, + addr_parser.decoders, addr_parser.count); + break; + default: + break; + } } bool @@ -181,8 +389,11 @@ sysdecode_netlink(FILE *fp, const void *buf, size_t len, int protocol) (const struct genlmsghdr *)(const void *) ((const char *)nl + sizeof(struct nlmsghdr)); + const size_t nlm_len = nl->nlmsg_len - + (sizeof(struct nlmsghdr) + + sizeof(struct genlmsghdr)); - sysdecode_netlink_pf(fp, genl); + sysdecode_netlink_pf(fp, genl, nlm_len); } fprintf(fp, "}");home | help
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