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netlink: some refactoring of NETLINK_GENERIC layer

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- Statically initialize control family/group.  This removes extra startup
code and provides a strong guarantee that they reside at the 0 index of
the respective arrays.  Before a genl_register_family() with a higher
SYSINIT order could try to hijack index 0.

- Remove the family_id field completely.  Now the family ID as well as
group ID are array indices and there is basically no place for a mistake.
Previous code had a bug where a KPI user could induce an ID mismatch.

- Merge netlink_generic_kpi.c to netlink_generic.c.  Both files are small
and now there is more dependency between the control family and the family
allocator. Ok'ed by melifaro@.

Reviewed by:		melifaro
Differential Revision:	https://reviews.freebsd.org/D48316
This commit is contained in:
Gleb Smirnoff 2025-01-10 20:59:29 -08:00
parent 26d1ad5a44
commit 926d2eadcb
5 changed files with 273 additions and 301 deletions
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1
sys/conf/files
View file

@ -4481,7 +4481,6 @@ netipsec/xform_ipcomp.c optional ipsec inet | ipsec inet6
netipsec/xform_tcp.c optional ipsec inet tcp_signature | \
ipsec inet6 tcp_signature | ipsec_support inet tcp_signature | \
ipsec_support inet6 tcp_signature
netlink/netlink_generic_kpi.c standard
netlink/netlink_glue.c standard
netlink/netlink_message_parser.c standard
netlink/netlink_domain.c optional netlink

2
sys/netlink/netlink_ctl.h
View file

@ -92,7 +92,7 @@ struct genl_cmd {
uint32_t cmd_num;
};
uint32_t genl_register_family(const char *family_name, size_t hdrsize,
uint16_t genl_register_family(const char *family_name, size_t hdrsize,
uint16_t family_version, uint16_t max_attr_idx);
bool genl_unregister_family(const char *family_name);
bool genl_register_cmds(const char *family_name, const struct genl_cmd *cmds,

291
sys/netlink/netlink_generic.c
View file

@ -119,7 +119,7 @@ dump_family(struct nlmsghdr *hdr, struct genlmsghdr *ghdr,
ghdr_new->reserved = 0;
nlattr_add_string(nw, CTRL_ATTR_FAMILY_NAME, gf->family_name);
nlattr_add_u16(nw, CTRL_ATTR_FAMILY_ID, gf->family_id);
nlattr_add_u16(nw, CTRL_ATTR_FAMILY_ID, genl_get_family_id(gf));
nlattr_add_u32(nw, CTRL_ATTR_VERSION, gf->family_version);
nlattr_add_u32(nw, CTRL_ATTR_HDRSIZE, gf->family_hdrsize);
nlattr_add_u32(nw, CTRL_ATTR_MAXATTR, gf->family_attr_max);
@ -173,9 +173,6 @@ enomem:
static void nlctrl_notify(void *arg, const struct genl_family *gf, int action);
static eventhandler_tag family_event_tag;
static uint32_t ctrl_family_id;
static uint32_t ctrl_group_id;
struct nl_parsed_family {
uint32_t family_id;
char *family_name;
@ -201,7 +198,7 @@ match_family(const struct genl_family *gf, const struct nl_parsed_family *attrs)
{
if (gf->family_name == NULL)
return (false);
if (attrs->family_id != 0 && attrs->family_id != gf->family_id)
if (attrs->family_id != 0 && attrs->family_id != genl_get_family_id(gf))
return (false);
if (attrs->family_name != NULL && strcmp(attrs->family_name, gf->family_name))
return (false);
@ -259,7 +256,7 @@ nlctrl_notify(void *arg __unused, const struct genl_family *gf, int cmd)
struct genlmsghdr ghdr = { .cmd = cmd };
struct nl_writer nw;
if (!nl_writer_group(&nw, NLMSG_SMALL, NETLINK_GENERIC, ctrl_group_id,
if (!nl_writer_group(&nw, NLMSG_SMALL, NETLINK_GENERIC, CTRL_GROUP_ID,
0, false)) {
NL_LOG(LOG_DEBUG, "error allocating group writer");
return;
@ -269,27 +266,16 @@ nlctrl_notify(void *arg __unused, const struct genl_family *gf, int cmd)
nlmsg_flush(&nw);
}
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 const struct nlhdr_parser *all_parsers[] = { &genl_parser };
static void
genl_load_all(void *u __unused)
{
NL_VERIFY_PARSERS(all_parsers);
ctrl_family_id = genl_register_family(CTRL_FAMILY_NAME, 0, 2, CTRL_ATTR_MAX);
genl_register_cmds(CTRL_FAMILY_NAME, nlctrl_cmds, nitems(nlctrl_cmds));
ctrl_group_id = genl_register_group(CTRL_FAMILY_NAME, "notify");
family_event_tag = EVENTHANDLER_REGISTER(genl_family_event, nlctrl_notify, NULL,
EVENTHANDLER_PRI_ANY);
netlink_register_proto(NETLINK_GENERIC, "NETLINK_GENERIC", genl_handle_message);
family_event_tag = EVENTHANDLER_REGISTER(genl_family_event,
nlctrl_notify, NULL, EVENTHANDLER_PRI_ANY);
netlink_register_proto(NETLINK_GENERIC, "NETLINK_GENERIC",
genl_handle_message);
}
SYSINIT(genl_load_all, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, genl_load_all, NULL);
@ -298,7 +284,268 @@ genl_unload(void *u __unused)
{
netlink_unregister_proto(NETLINK_GENERIC);
EVENTHANDLER_DEREGISTER(genl_family_event, family_event_tag);
genl_unregister_family(CTRL_FAMILY_NAME);
NET_EPOCH_WAIT();
}
SYSUNINIT(genl_unload, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, genl_unload, NULL);
/*
* Public KPI for NETLINK_GENERIC families/groups registration logic below.
*/
static struct sx sx_lock;
SX_SYSINIT(genl_lock, &sx_lock, "genetlink lock");
#define GENL_LOCK() sx_xlock(&sx_lock)
#define GENL_UNLOCK() sx_xunlock(&sx_lock)
#define GENL_ASSERT_LOCKED() sx_assert(&sx_lock, SA_LOCKED)
#define GENL_ASSERT_XLOCKED() sx_assert(&sx_lock, SA_XLOCKED)
static struct genl_cmd nlctrl_cmds[] = {
[CTRL_CMD_GETFAMILY] = {
.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 struct genl_family families[MAX_FAMILIES] = {
[CTRL_FAMILY_ID] = {
.family_name = CTRL_FAMILY_NAME,
.family_hdrsize = 0,
.family_version = 2,
.family_attr_max = CTRL_ATTR_MAX,
.family_cmd_size = CTRL_CMD_GETFAMILY + 1,
.family_cmds = nlctrl_cmds,
.family_num_groups = 1,
},
}
;
static struct genl_group groups[MAX_GROUPS] = {
[CTRL_GROUP_ID] = {
.group_family = &families[CTRL_FAMILY_ID],
.group_name = CTRL_GROUP_NAME,
},
};
static struct genl_family *
find_family(const char *family_name)
{
GENL_ASSERT_LOCKED();
for (u_int i = 0; i < MAX_FAMILIES; i++)
if (families[i].family_name != NULL &&
strcmp(families[i].family_name, family_name) == 0)
return (&families[i]);
return (NULL);
}
static struct genl_family *
find_empty_family_id(const char *family_name)
{
GENL_ASSERT_LOCKED();
/* Microoptimization: index 0 is reserved for the control family */
for (u_int i = 1; i < MAX_FAMILIES; i++)
if (families[i].family_name == NULL)
return (&families[i]);
return (NULL);
}
uint16_t
genl_register_family(const char *family_name, size_t hdrsize,
uint16_t family_version, uint16_t max_attr_idx)
{
struct genl_family *gf;
uint16_t family_id;
GENL_LOCK();
if (find_family(family_name) != NULL) {
GENL_UNLOCK();
return (0);
}
gf = find_empty_family_id(family_name);
KASSERT(gf, ("%s: maximum of %u generic netlink families allocated",
__func__, MAX_FAMILIES));
*gf = (struct genl_family) {
.family_name = family_name,
.family_version = family_version,
.family_hdrsize = hdrsize,
.family_attr_max = max_attr_idx,
};
family_id = genl_get_family_id(gf);
GENL_UNLOCK();
NL_LOG(LOG_DEBUG2, "Registered family %s id %d", gf->family_name,
family_id);
EVENTHANDLER_INVOKE(genl_family_event, gf, CTRL_CMD_NEWFAMILY);
return (family_id);
}
static void
free_family(struct genl_family *gf)
{
if (gf->family_cmds != NULL)
free(gf->family_cmds, M_NETLINK);
}
/*
* unregister groups of a given family
*/
static void
unregister_groups(const struct genl_family *gf)
{
for (u_int i = 0; i < MAX_GROUPS; i++) {
struct genl_group *gg = &groups[i];
if (gg->group_family == gf && gg->group_name != NULL) {
gg->group_family = NULL;
gg->group_name = NULL;
}
}
}
/*
* 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);
if (gf != NULL) {
EVENTHANDLER_INVOKE(genl_family_event, gf, CTRL_CMD_DELFAMILY);
found = true;
unregister_groups(gf);
/* 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)
{
struct genl_family *gf;
uint16_t cmd_size;
GENL_LOCK();
if ((gf = find_family(family_name)) == NULL) {
GENL_UNLOCK();
return (false);
}
cmd_size = gf->family_cmd_size;
for (u_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) {
void *old_data;
/* 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));
old_data = gf->family_cmds;
gf->family_cmds = data;
gf->family_cmd_size = cmd_size;
free(old_data, M_NETLINK);
}
for (u_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 (u_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)
{
struct genl_family *gf;
uint32_t group_id = 0;
MPASS(family_name != NULL);
MPASS(group_name != NULL);
GENL_LOCK();
if ((gf = find_family(family_name)) == NULL ||
find_group(gf, group_name) != NULL) {
GENL_UNLOCK();
return (0);
}
/* Microoptimization: index 0 is reserved for the control family */
for (u_int i = 1; 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);
}
/* accessors */
struct genl_family *
genl_get_family(uint16_t family_id)
{
return ((family_id < MAX_FAMILIES) ? &families[family_id] : NULL);
}
const char *
genl_get_family_name(const struct genl_family *gf)
{
return (gf->family_name);
}
uint16_t
genl_get_family_id(const struct genl_family *gf)
{
MPASS(gf >= &families[0] && gf < &families[MAX_FAMILIES]);
return ((uint16_t)(gf - &families[0]) + GENL_MIN_ID);
}
struct genl_group *
genl_get_group(uint32_t group_id)
{
return ((group_id < MAX_GROUPS) ? &groups[group_id] : NULL);
}

276
sys/netlink/netlink_generic_kpi.c
View file

@ -1,276 +0,0 @@
/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2022 Alexander V. Chernikov <melifaro@FreeBSD.org>
*
* 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/types.h>
#include <sys/ck.h>
#include <sys/epoch.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/sx.h>
#include <netlink/netlink.h>
#include <netlink/netlink_ctl.h>
#include <netlink/netlink_generic.h>
#include <netlink/netlink_var.h>
#define DEBUG_MOD_NAME nl_generic_kpi
#define DEBUG_MAX_LEVEL LOG_DEBUG3
#include <netlink/netlink_debug.h>
_DECLARE_DEBUG(LOG_INFO);
/*
* NETLINK_GENERIC families/groups registration logic
*/
#define GENL_LOCK() sx_xlock(&sx_lock)
#define GENL_UNLOCK() sx_xunlock(&sx_lock)
static struct sx sx_lock;
SX_SYSINIT(genl_lock, &sx_lock, "genetlink lock");
static struct genl_family families[MAX_FAMILIES];
static struct genl_group groups[MAX_GROUPS];
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);
}
static struct genl_family *
find_empty_family_id(const char *family_name)
{
struct genl_family *gf = NULL;
if (!strcmp(family_name, CTRL_FAMILY_NAME)) {
gf = &families[0];
gf->family_id = GENL_MIN_ID;
} else {
/* Index 0 is reserved for the control family */
for (int i = 1; i < MAX_FAMILIES; i++) {
gf = &families[i];
if (gf->family_name == NULL) {
gf->family_id = GENL_MIN_ID + i;
break;
}
}
}
return (gf);
}
uint32_t
genl_register_family(const char *family_name, size_t hdrsize,
uint16_t family_version, uint16_t max_attr_idx)
{
MPASS(family_name != NULL);
if (find_family(family_name) != NULL)
return (0);
GENL_LOCK();
struct genl_family *gf = find_empty_family_id(family_name);
MPASS(gf != NULL);
gf->family_name = family_name;
gf->family_version = family_version;
gf->family_hdrsize = hdrsize;
gf->family_attr_max = max_attr_idx;
NL_LOG(LOG_DEBUG2, "Registered family %s id %d", gf->family_name,
gf->family_id);
EVENTHANDLER_INVOKE(genl_family_event, gf, CTRL_CMD_NEWFAMILY);
GENL_UNLOCK();
return (gf->family_id);
}
static void
free_family(struct genl_family *gf)
{
if (gf->family_cmds != NULL)
free(gf->family_cmds, M_NETLINK);
}
/*
* unregister groups of a given family
*/
static void
unregister_groups(const struct genl_family *gf)
{
for (int i = 0; i < MAX_GROUPS; i++) {
struct genl_group *gg = &groups[i];
if (gg->group_family == gf && gg->group_name != NULL) {
gg->group_family = NULL;
gg->group_name = NULL;
}
}
}
/*
* 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);
if (gf != NULL) {
EVENTHANDLER_INVOKE(genl_family_event, gf, CTRL_CMD_DELFAMILY);
found = true;
unregister_groups(gf);
/* 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);
}
/* accessors */
struct genl_family *
genl_get_family(uint16_t family_id)
{
return ((family_id < MAX_FAMILIES) ? &families[family_id] : NULL);
}
const char *
genl_get_family_name(const struct genl_family *gf)
{
return (gf->family_name);
}
uint16_t
genl_get_family_id(const struct genl_family *gf)
{
return (gf->family_id);
}
struct genl_group *
genl_get_group(uint32_t group_id)
{
return ((group_id < MAX_GROUPS) ? &groups[group_id] : NULL);
}

4
sys/netlink/netlink_var.h
View file

@ -147,7 +147,6 @@ void nl_buf_free(struct nl_buf *nb);
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;
@ -168,7 +167,10 @@ struct genl_group *genl_get_group(uint32_t group_id);
#define MIN_GROUP_NUM 48
#define CTRL_FAMILY_ID 0
#define CTRL_FAMILY_NAME "nlctrl"
#define CTRL_GROUP_ID 0
#define CTRL_GROUP_NAME "notify"
struct ifnet;
struct nl_parsed_link;