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sys/netlink/netlink_generic.c

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/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2022 Alexander V. Chernikov
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/malloc.h>
#include <sys/priv.h>
#include <sys/socket.h>
#include <sys/ck.h>
#include <netlink/netlink.h>
#include <netlink/netlink_ctl.h>
#include <netlink/netlink_var.h>
#include <netlink/netlink_generic.h>
#define DEBUG_MOD_NAME nl_generic
#define DEBUG_MAX_LEVEL LOG_DEBUG3
#include <netlink/netlink_debug.h>
_DECLARE_DEBUG(LOG_DEBUG3);
#define MAX_FAMILIES 20
#define MAX_GROUPS 20
#define MIN_GROUP_NUM 48
static struct sx sx_lock;
#define GENL_LOCK_INIT() sx_init(&sx_lock, "genetlink lock")
#define GENL_LOCK_DESTROY() sx_destroy(&sx_lock)
#define GENL_LOCK() sx_xlock(&sx_lock)
#define GENL_UNLOCK() sx_xunlock(&sx_lock)
struct genl_family {
const char *family_name;
uint16_t family_hdrsize;
uint16_t family_id;
uint16_t family_version;
uint16_t family_attr_max;
uint16_t family_cmd_size;
uint16_t family_num_groups;
struct genl_cmd *family_cmds;
};
static struct genl_family families[MAX_FAMILIES];
struct genl_group {
struct genl_family *group_family;
const char *group_name;
};
static struct genl_group groups[MAX_GROUPS];
static int dump_family(struct nlmsghdr *hdr, struct genlmsghdr *ghdr,
const struct genl_family *gf, struct nlmsg_state *ns);
static void nlctrl_notify(const struct genl_family *gf, int action);
static struct genl_family *
find_family(const char *family_name)
{
for (int i = 0; i < MAX_FAMILIES; i++) {
struct genl_family *gf = &families[i];
if (gf->family_name != NULL && !strcmp(gf->family_name, family_name))
return (gf);
}
return (NULL);
}
uint32_t
genl_register_family(const char *family_name, size_t hdrsize, int family_version,
int max_attr_idx)
{
uint32_t family_id = 0;
MPASS(family_name != NULL);
if (find_family(family_name) != NULL)
return (0);
GENL_LOCK();
for (int i = 0; i < MAX_FAMILIES; i++) {
struct genl_family *gf = &families[i];
if (gf->family_name == NULL) {
gf->family_name = family_name;
gf->family_version = family_version;
gf->family_hdrsize = hdrsize;
gf->family_attr_max = max_attr_idx;
gf->family_id = i + GENL_MIN_ID;
NL_LOG(LOG_DEBUG2, "Registered family %s id %d",
gf->family_name, gf->family_id);
family_id = gf->family_id;
nlctrl_notify(gf, CTRL_CMD_NEWFAMILY);
break;
}
}
GENL_UNLOCK();
return (family_id);
}
static void
free_family(struct genl_family *gf)
{
if (gf->family_cmds != NULL)
free(gf->family_cmds, M_NETLINK);
}
/*
* Can sleep, I guess
*/
bool
genl_unregister_family(const char *family_name)
{
bool found = false;
GENL_LOCK();
struct genl_family *gf = find_family(family_name);
nlctrl_notify(gf, CTRL_CMD_DELFAMILY);
if (gf != NULL) {
found = true;
/* TODO: zero pointer first */
free_family(gf);
bzero(gf, sizeof(*gf));
}
GENL_UNLOCK();
return (found);
}
bool
genl_register_cmds(const char *family_name, const struct genl_cmd *cmds, int count)
{
GENL_LOCK();
struct genl_family *gf = find_family(family_name);
if (gf == NULL) {
GENL_UNLOCK();
return (false);
}
int cmd_size = gf->family_cmd_size;
for (int i = 0; i < count; i++) {
MPASS(cmds[i].cmd_cb != NULL);
if (cmds[i].cmd_num >= cmd_size)
cmd_size = cmds[i].cmd_num + 1;
}
if (cmd_size > gf->family_cmd_size) {
/* need to realloc */
size_t sz = cmd_size * sizeof(struct genl_cmd);
void *data = malloc(sz, M_NETLINK, M_WAITOK | M_ZERO);
memcpy(data, gf->family_cmds, gf->family_cmd_size * sizeof(struct genl_cmd));
void *old_data = gf->family_cmds;
gf->family_cmds = data;
gf->family_cmd_size = cmd_size;
free(old_data, M_NETLINK);
}
for (int i = 0; i < count; i++) {
const struct genl_cmd *cmd = &cmds[i];
MPASS(gf->family_cmds[cmd->cmd_num].cmd_cb == NULL);
gf->family_cmds[cmd->cmd_num] = cmds[i];
NL_LOG(LOG_DEBUG2, "Adding cmd %s(%d) to family %s",
cmd->cmd_name, cmd->cmd_num, gf->family_name);
}
GENL_UNLOCK();
return (true);
}
static struct genl_group *
find_group(const struct genl_family *gf, const char *group_name)
{
for (int i = 0; i < MAX_GROUPS; i++) {
struct genl_group *gg = &groups[i];
if (gg->group_family == gf && !strcmp(gg->group_name, group_name))
return (gg);
}
return (NULL);
}
uint32_t
genl_register_group(const char *family_name, const char *group_name)
{
uint32_t group_id = 0;
MPASS(family_name != NULL);
MPASS(group_name != NULL);
GENL_LOCK();
struct genl_family *gf = find_family(family_name);
if (gf == NULL || find_group(gf, group_name) != NULL) {
GENL_UNLOCK();
return (0);
}
for (int i = 0; i < MAX_GROUPS; i++) {
struct genl_group *gg = &groups[i];
if (gg->group_family == NULL) {
gf->family_num_groups++;
gg->group_family = gf;
gg->group_name = group_name;
group_id = i + MIN_GROUP_NUM;
break;
}
}
GENL_UNLOCK();
return (group_id);
}
/*
* Handler called by netlink subsystem when matching netlink message is received
*/
static int
genl_handle_message(struct nlmsghdr *hdr, struct netlink_parse_tracker *npt)
{
struct nlpcb *nlp = npt->nlp;
int error = 0;
int family_id = (int)hdr->nlmsg_type - GENL_MIN_ID;
if (__predict_false(family_id < 0 || family_id > MAX_FAMILIES)) {
NLP_LOG(LOG_DEBUG, nlp, "invalid message type: %d", hdr->nlmsg_type);
return (ENOTSUP);
}
if (__predict_false(hdr->nlmsg_len < sizeof(hdr) + GENL_HDRLEN)) {
NLP_LOG(LOG_DEBUG, nlp, "invalid message size: %d", hdr->nlmsg_len);
return (EINVAL);
}
struct genl_family *gf = &families[family_id];
struct genlmsghdr *ghdr = (struct genlmsghdr *)(hdr + 1);
if (ghdr->cmd >= gf->family_cmd_size || gf->family_cmds[ghdr->cmd].cmd_cb == NULL) {
NLP_LOG(LOG_DEBUG, nlp, "family %s: invalid cmd %d",
gf->family_name, ghdr->cmd);
return (ENOTSUP);
}
struct genl_cmd *cmd = &gf->family_cmds[ghdr->cmd];
if (cmd->cmd_priv != 0 && !nlp_has_priv(nlp, cmd->cmd_priv)) {
NLP_LOG(LOG_DEBUG, nlp, "family %s: cmd %d priv_check() failed",
gf->family_name, ghdr->cmd);
return (EPERM);
}
NLP_LOG(LOG_DEBUG2, nlp, "received family %s cmd %s(%d) len %d",
gf->family_name, cmd->cmd_name, ghdr->cmd, hdr->nlmsg_len);
error = cmd->cmd_cb(hdr, npt);
return (error);
}
static uint32_t
get_cmd_flags(const struct genl_cmd *cmd)
{
uint32_t flags = cmd->cmd_flags;
if (cmd->cmd_priv != 0)
flags |= GENL_ADMIN_PERM;
return (flags);
}
static int
dump_family(struct nlmsghdr *hdr, struct genlmsghdr *ghdr,
const struct genl_family *gf, struct nlmsg_state *ns)
{
if (!nlmsg_reply(ns, hdr, sizeof(struct genlmsghdr)))
goto enomem;
struct genlmsghdr *ghdr_new = nlmsg_reserve_object(ns, struct genlmsghdr);
ghdr_new->cmd = ghdr->cmd;
ghdr_new->version = gf->family_version;
ghdr_new->reserved = 0;
nlattr_add_string(ns, CTRL_ATTR_FAMILY_NAME, gf->family_name);
nlattr_add_u16(ns, CTRL_ATTR_FAMILY_ID, gf->family_id);
nlattr_add_u32(ns, CTRL_ATTR_VERSION, gf->family_version);
nlattr_add_u32(ns, CTRL_ATTR_HDRSIZE, gf->family_hdrsize);
nlattr_add_u32(ns, CTRL_ATTR_MAXATTR, gf->family_attr_max);
if (gf->family_cmd_size > 0) {
int off = nlattr_add_nested(ns, CTRL_ATTR_OPS);
if (off == 0)
goto enomem;
for (int i = 0, cnt=0; i < gf->family_cmd_size; i++) {
struct genl_cmd *cmd = &gf->family_cmds[i];
if (cmd->cmd_cb == NULL)
continue;
int cmd_off = nlattr_add_nested(ns, ++cnt);
if (cmd_off == 0)
goto enomem;
nlattr_add_u32(ns, CTRL_ATTR_OP_ID, cmd->cmd_num);
nlattr_add_u32(ns, CTRL_ATTR_OP_FLAGS, get_cmd_flags(cmd));
nlattr_set_len(ns, cmd_off);
}
nlattr_set_len(ns, off);
}
if (gf->family_num_groups > 0) {
int off = nlattr_add_nested(ns, CTRL_ATTR_MCAST_GROUPS);
if (off == 0)
goto enomem;
for (int i = 0, cnt = 0; i < MAX_GROUPS; i++) {
struct genl_group *gg = &groups[i];
if (gg->group_family != gf)
continue;
int cmd_off = nlattr_add_nested(ns, ++cnt);
if (cmd_off == 0)
goto enomem;
nlattr_add_u32(ns, CTRL_ATTR_MCAST_GRP_ID, i + MIN_GROUP_NUM);
nlattr_add_string(ns, CTRL_ATTR_MCAST_GRP_NAME, gg->group_name);
nlattr_set_len(ns, cmd_off);
}
nlattr_set_len(ns, off);
}
if (nlmsg_end(ns))
return (0);
enomem:
NL_LOG(LOG_DEBUG, "unable to dump family %s state (ENOMEM)", gf->family_name);
nlmsg_abort(ns);
return (ENOMEM);
}
/* Declare ourself as a user */
#define CTRL_FAMILY_NAME "nlctrl"
static uint32_t ctrl_family_id;
static uint32_t ctrl_group_id;
struct nl_parsed_family {
uint32_t family_id;
char *family_name;
};
#define _OFF_S(_field) offsetof(struct nl_parsed_family, _field)
static struct nlattr_parser ps_family[] = {
{ .type = CTRL_ATTR_FAMILY_ID , .off = _OFF_S(family_id), .cb = nlattr_get_uint32 },
{ .type = CTRL_ATTR_FAMILY_NAME , .off = _OFF_S(family_id), .cb = nlattr_get_string },
};
#undef _OFF_S
static struct nlhdr_parser family_parser = {
.hdr_off = sizeof(struct genlmsghdr),
.np_size = NL_ARRAY_LEN(ps_family),
.np = ps_family,
};
static int
nlctrl_handle_getfamily(struct nlmsghdr *hdr, struct netlink_parse_tracker *npt)
{
int error = 0;
struct nl_parsed_family attrs = {};
error = nl_parse_nlmsg(hdr, &family_parser, npt, &attrs);
if (error != 0)
return (error);
struct genlmsghdr ghdr = {
.cmd = CTRL_CMD_NEWFAMILY,
};
for (int i = 0; i < MAX_FAMILIES; i++) {
struct genl_family *gf = &families[i];
if (gf->family_name == NULL)
continue;
if (attrs.family_id != 0 && attrs.family_id != gf->family_id)
continue;
if (attrs.family_name != NULL && strcmp(attrs.family_name, gf->family_name))
continue;
error = dump_family(hdr, &ghdr, &families[i], npt->ns);
if (error != 0)
break;
}
return (error);
}
static void
nlctrl_notify(const struct genl_family *gf, int cmd)
{
struct nlmsghdr hdr = {.nlmsg_type = NETLINK_GENERIC };
struct genlmsghdr ghdr = { .cmd = cmd };
struct nlmsg_state ns = {};
if (nlmsg_get_group_writer(NLMSG_SMALL, NETLINK_GENERIC, ctrl_group_id, &ns)) {
dump_family(&hdr, &ghdr, gf, &ns);
nlmsg_flush(&ns);
return;
}
NL_LOG(LOG_DEBUG, "error allocating group writer");
}
static const struct genl_cmd nlctrl_cmds[] = {
{
.cmd_num = CTRL_CMD_GETFAMILY,
.cmd_name = "GETFAMILY",
.cmd_cb = nlctrl_handle_getfamily,
.cmd_flags = GENL_CMD_CAP_DO | GENL_CMD_CAP_DUMP, GENL_CMD_CAP_HASPOL,
},
};
static void
genl_nlctrl_init()
{
ctrl_family_id = genl_register_family(CTRL_FAMILY_NAME, 0, 2, CTRL_ATTR_MAX);
genl_register_cmds(CTRL_FAMILY_NAME, nlctrl_cmds, NL_ARRAY_LEN(nlctrl_cmds));
ctrl_group_id = genl_register_group(CTRL_FAMILY_NAME, "notify");
}
static void
genl_nlctrl_destroy()
{
genl_unregister_family(CTRL_FAMILY_NAME);
}
static void
genl_load(void *u __unused)
{
GENL_LOCK_INIT();
netlink_register_proto(NETLINK_GENERIC, "NETLINK_GENERIC", genl_handle_message);
genl_nlctrl_init();
}
SYSINIT(genl_load, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, genl_load, NULL);
static void
genl_unload(void *u __unused)
{
genl_nlctrl_destroy();
GENL_LOCK_DESTROY();
epoch_wait_preempt(net_epoch_preempt);
}
SYSUNINIT(genl_unload, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, genl_unload, NULL);