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DEFINITIONS
This source file includes following definitions.
- genl_lock
- genl_unlock
- genl_family_hash
- genl_family_chain
- genl_family_find_byid
- genl_family_find_byname
- genl_get_cmd
- genl_generate_id
- genl_register_mc_group
- __genl_unregister_mc_group
- genl_unregister_mc_group
- genl_unregister_mc_groups
- genl_register_ops
- genl_unregister_ops
- genl_register_family
- genl_unregister_family
- genl_rcv_msg
- genl_rcv
- ctrl_fill_info
- ctrl_fill_mcgrp_info
- ctrl_dumpfamily
- ctrl_build_family_msg
- ctrl_build_mcgrp_msg
- ctrl_getfamily
- genl_ctrl_event
- genl_init
/*
* NETLINK Generic Netlink Family
*
* Authors: Jamal Hadi Salim
* Thomas Graf <tgraf@suug.ch>
* Johannes Berg <johannes@sipsolutions.net>
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <linux/mutex.h>
#include <linux/bitmap.h>
#include <net/sock.h>
#include <net/genetlink.h>
struct sock *genl_sock = NULL;
static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
static inline void genl_lock(void)
{
mutex_lock(&genl_mutex);
}
static inline void genl_unlock(void)
{
mutex_unlock(&genl_mutex);
}
#define GENL_FAM_TAB_SIZE 16
#define GENL_FAM_TAB_MASK (GENL_FAM_TAB_SIZE - 1)
static struct list_head family_ht[GENL_FAM_TAB_SIZE];
/*
* Bitmap of multicast groups that are currently in use.
*
* To avoid an allocation at boot of just one unsigned long,
* declare it global instead.
* Bit 0 is marked as already used since group 0 is invalid.
*/
static unsigned long mc_group_start = 0x1;
static unsigned long *mc_groups = &mc_group_start;
static unsigned long mc_groups_longs = 1;
static int genl_ctrl_event(int event, void *data);
static inline unsigned int genl_family_hash(unsigned int id)
{
return id & GENL_FAM_TAB_MASK;
}
static inline struct list_head *genl_family_chain(unsigned int id)
{
return &family_ht[genl_family_hash(id)];
}
static struct genl_family *genl_family_find_byid(unsigned int id)
{
struct genl_family *f;
list_for_each_entry(f, genl_family_chain(id), family_list)
if (f->id == id)
return f;
return NULL;
}
static struct genl_family *genl_family_find_byname(char *name)
{
struct genl_family *f;
int i;
for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
list_for_each_entry(f, genl_family_chain(i), family_list)
if (strcmp(f->name, name) == 0)
return f;
return NULL;
}
static struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
{
struct genl_ops *ops;
list_for_each_entry(ops, &family->ops_list, ops_list)
if (ops->cmd == cmd)
return ops;
return NULL;
}
/* Of course we are going to have problems once we hit
* 2^16 alive types, but that can only happen by year 2K
*/
static inline u16 genl_generate_id(void)
{
static u16 id_gen_idx;
int overflowed = 0;
do {
if (id_gen_idx == 0)
id_gen_idx = GENL_MIN_ID;
if (++id_gen_idx > GENL_MAX_ID) {
if (!overflowed) {
overflowed = 1;
id_gen_idx = 0;
continue;
} else
return 0;
}
} while (genl_family_find_byid(id_gen_idx));
return id_gen_idx;
}
static struct genl_multicast_group notify_grp;
/**
* genl_register_mc_group - register a multicast group
*
* Registers the specified multicast group and notifies userspace
* about the new group.
*
* Returns 0 on success or a negative error code.
*
* @family: The generic netlink family the group shall be registered for.
* @grp: The group to register, must have a name.
*/
int genl_register_mc_group(struct genl_family *family,
struct genl_multicast_group *grp)
{
int id;
unsigned long *new_groups;
int err;
BUG_ON(grp->name[0] == '\0');
genl_lock();
/* special-case our own group */
if (grp == ¬ify_grp)
id = GENL_ID_CTRL;
else
id = find_first_zero_bit(mc_groups,
mc_groups_longs * BITS_PER_LONG);
if (id >= mc_groups_longs * BITS_PER_LONG) {
size_t nlen = (mc_groups_longs + 1) * sizeof(unsigned long);
if (mc_groups == &mc_group_start) {
new_groups = kzalloc(nlen, GFP_KERNEL);
if (!new_groups) {
err = -ENOMEM;
goto out;
}
mc_groups = new_groups;
*mc_groups = mc_group_start;
} else {
new_groups = krealloc(mc_groups, nlen, GFP_KERNEL);
if (!new_groups) {
err = -ENOMEM;
goto out;
}
mc_groups = new_groups;
mc_groups[mc_groups_longs] = 0;
}
mc_groups_longs++;
}
err = netlink_change_ngroups(genl_sock,
mc_groups_longs * BITS_PER_LONG);
if (err)
goto out;
grp->id = id;
set_bit(id, mc_groups);
list_add_tail(&grp->list, &family->mcast_groups);
grp->family = family;
genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, grp);
out:
genl_unlock();
return err;
}
EXPORT_SYMBOL(genl_register_mc_group);
static void __genl_unregister_mc_group(struct genl_family *family,
struct genl_multicast_group *grp)
{
BUG_ON(grp->family != family);
netlink_clear_multicast_users(genl_sock, grp->id);
clear_bit(grp->id, mc_groups);
list_del(&grp->list);
genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, grp);
grp->id = 0;
grp->family = NULL;
}
/**
* genl_unregister_mc_group - unregister a multicast group
*
* Unregisters the specified multicast group and notifies userspace
* about it. All current listeners on the group are removed.
*
* Note: It is not necessary to unregister all multicast groups before
* unregistering the family, unregistering the family will cause
* all assigned multicast groups to be unregistered automatically.
*
* @family: Generic netlink family the group belongs to.
* @grp: The group to unregister, must have been registered successfully
* previously.
*/
void genl_unregister_mc_group(struct genl_family *family,
struct genl_multicast_group *grp)
{
genl_lock();
__genl_unregister_mc_group(family, grp);
genl_unlock();
}
static void genl_unregister_mc_groups(struct genl_family *family)
{
struct genl_multicast_group *grp, *tmp;
list_for_each_entry_safe(grp, tmp, &family->mcast_groups, list)
__genl_unregister_mc_group(family, grp);
}
/**
* genl_register_ops - register generic netlink operations
* @family: generic netlink family
* @ops: operations to be registered
*
* Registers the specified operations and assigns them to the specified
* family. Either a doit or dumpit callback must be specified or the
* operation will fail. Only one operation structure per command
* identifier may be registered.
*
* See include/net/genetlink.h for more documenation on the operations
* structure.
*
* Returns 0 on success or a negative error code.
*/
int genl_register_ops(struct genl_family *family, struct genl_ops *ops)
{
int err = -EINVAL;
if (ops->dumpit == NULL && ops->doit == NULL)
goto errout;
if (genl_get_cmd(ops->cmd, family)) {
err = -EEXIST;
goto errout;
}
if (ops->dumpit)
ops->flags |= GENL_CMD_CAP_DUMP;
if (ops->doit)
ops->flags |= GENL_CMD_CAP_DO;
if (ops->policy)
ops->flags |= GENL_CMD_CAP_HASPOL;
genl_lock();
list_add_tail(&ops->ops_list, &family->ops_list);
genl_unlock();
genl_ctrl_event(CTRL_CMD_NEWOPS, ops);
err = 0;
errout:
return err;
}
/**
* genl_unregister_ops - unregister generic netlink operations
* @family: generic netlink family
* @ops: operations to be unregistered
*
* Unregisters the specified operations and unassigns them from the
* specified family. The operation blocks until the current message
* processing has finished and doesn't start again until the
* unregister process has finished.
*
* Note: It is not necessary to unregister all operations before
* unregistering the family, unregistering the family will cause
* all assigned operations to be unregistered automatically.
*
* Returns 0 on success or a negative error code.
*/
int genl_unregister_ops(struct genl_family *family, struct genl_ops *ops)
{
struct genl_ops *rc;
genl_lock();
list_for_each_entry(rc, &family->ops_list, ops_list) {
if (rc == ops) {
list_del(&ops->ops_list);
genl_unlock();
genl_ctrl_event(CTRL_CMD_DELOPS, ops);
return 0;
}
}
genl_unlock();
return -ENOENT;
}
/**
* genl_register_family - register a generic netlink family
* @family: generic netlink family
*
* Registers the specified family after validating it first. Only one
* family may be registered with the same family name or identifier.
* The family id may equal GENL_ID_GENERATE causing an unique id to
* be automatically generated and assigned.
*
* Return 0 on success or a negative error code.
*/
int genl_register_family(struct genl_family *family)
{
int err = -EINVAL;
if (family->id && family->id < GENL_MIN_ID)
goto errout;
if (family->id > GENL_MAX_ID)
goto errout;
INIT_LIST_HEAD(&family->ops_list);
INIT_LIST_HEAD(&family->mcast_groups);
genl_lock();
if (genl_family_find_byname(family->name)) {
err = -EEXIST;
goto errout_locked;
}
if (genl_family_find_byid(family->id)) {
err = -EEXIST;
goto errout_locked;
}
if (family->id == GENL_ID_GENERATE) {
u16 newid = genl_generate_id();
if (!newid) {
err = -ENOMEM;
goto errout_locked;
}
family->id = newid;
}
if (family->maxattr) {
family->attrbuf = kmalloc((family->maxattr+1) *
sizeof(struct nlattr *), GFP_KERNEL);
if (family->attrbuf == NULL) {
err = -ENOMEM;
goto errout_locked;
}
} else
family->attrbuf = NULL;
list_add_tail(&family->family_list, genl_family_chain(family->id));
genl_unlock();
genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);
return 0;
errout_locked:
genl_unlock();
errout:
return err;
}
/**
* genl_unregister_family - unregister generic netlink family
* @family: generic netlink family
*
* Unregisters the specified family.
*
* Returns 0 on success or a negative error code.
*/
int genl_unregister_family(struct genl_family *family)
{
struct genl_family *rc;
genl_lock();
genl_unregister_mc_groups(family);
list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
if (family->id != rc->id || strcmp(rc->name, family->name))
continue;
list_del(&rc->family_list);
INIT_LIST_HEAD(&family->ops_list);
genl_unlock();
kfree(family->attrbuf);
genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
return 0;
}
genl_unlock();
return -ENOENT;
}
static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
struct genl_ops *ops;
struct genl_family *family;
struct genl_info info;
struct genlmsghdr *hdr = nlmsg_data(nlh);
int hdrlen, err;
family = genl_family_find_byid(nlh->nlmsg_type);
if (family == NULL)
return -ENOENT;
hdrlen = GENL_HDRLEN + family->hdrsize;
if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
return -EINVAL;
ops = genl_get_cmd(hdr->cmd, family);
if (ops == NULL)
return -EOPNOTSUPP;
if ((ops->flags & GENL_ADMIN_PERM) &&
security_netlink_recv(skb, CAP_NET_ADMIN))
return -EPERM;
if (nlh->nlmsg_flags & NLM_F_DUMP) {
if (ops->dumpit == NULL)
return -EOPNOTSUPP;
genl_unlock();
err = netlink_dump_start(genl_sock, skb, nlh,
ops->dumpit, ops->done);
genl_lock();
return err;
}
if (ops->doit == NULL)
return -EOPNOTSUPP;
if (family->attrbuf) {
err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr,
ops->policy);
if (err < 0)
return err;
}
info.snd_seq = nlh->nlmsg_seq;
info.snd_pid = NETLINK_CB(skb).pid;
info.nlhdr = nlh;
info.genlhdr = nlmsg_data(nlh);
info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
info.attrs = family->attrbuf;
return ops->doit(skb, &info);
}
static void genl_rcv(struct sk_buff *skb)
{
genl_lock();
netlink_rcv_skb(skb, &genl_rcv_msg);
genl_unlock();
}
/**************************************************************************
* Controller
**************************************************************************/
static struct genl_family genl_ctrl = {
.id = GENL_ID_CTRL,
.name = "nlctrl",
.version = 0x2,
.maxattr = CTRL_ATTR_MAX,
};
static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
u32 flags, struct sk_buff *skb, u8 cmd)
{
void *hdr;
hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
if (hdr == NULL)
return -1;
NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, family->name);
NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, family->id);
NLA_PUT_U32(skb, CTRL_ATTR_VERSION, family->version);
NLA_PUT_U32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize);
NLA_PUT_U32(skb, CTRL_ATTR_MAXATTR, family->maxattr);
if (!list_empty(&family->ops_list)) {
struct nlattr *nla_ops;
struct genl_ops *ops;
int idx = 1;
nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
if (nla_ops == NULL)
goto nla_put_failure;
list_for_each_entry(ops, &family->ops_list, ops_list) {
struct nlattr *nest;
nest = nla_nest_start(skb, idx++);
if (nest == NULL)
goto nla_put_failure;
NLA_PUT_U32(skb, CTRL_ATTR_OP_ID, ops->cmd);
NLA_PUT_U32(skb, CTRL_ATTR_OP_FLAGS, ops->flags);
nla_nest_end(skb, nest);
}
nla_nest_end(skb, nla_ops);
}
if (!list_empty(&family->mcast_groups)) {
struct genl_multicast_group *grp;
struct nlattr *nla_grps;
int idx = 1;
nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
if (nla_grps == NULL)
goto nla_put_failure;
list_for_each_entry(grp, &family->mcast_groups, list) {
struct nlattr *nest;
nest = nla_nest_start(skb, idx++);
if (nest == NULL)
goto nla_put_failure;
NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
grp->name);
nla_nest_end(skb, nest);
}
nla_nest_end(skb, nla_grps);
}
return genlmsg_end(skb, hdr);
nla_put_failure:
genlmsg_cancel(skb, hdr);
return -EMSGSIZE;
}
static int ctrl_fill_mcgrp_info(struct genl_multicast_group *grp, u32 pid,
u32 seq, u32 flags, struct sk_buff *skb,
u8 cmd)
{
void *hdr;
struct nlattr *nla_grps;
struct nlattr *nest;
hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
if (hdr == NULL)
return -1;
NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, grp->family->name);
NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, grp->family->id);
nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
if (nla_grps == NULL)
goto nla_put_failure;
nest = nla_nest_start(skb, 1);
if (nest == NULL)
goto nla_put_failure;
NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
grp->name);
nla_nest_end(skb, nest);
nla_nest_end(skb, nla_grps);
return genlmsg_end(skb, hdr);
nla_put_failure:
genlmsg_cancel(skb, hdr);
return -EMSGSIZE;
}
static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
{
int i, n = 0;
struct genl_family *rt;
int chains_to_skip = cb->args[0];
int fams_to_skip = cb->args[1];
for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
if (i < chains_to_skip)
continue;
n = 0;
list_for_each_entry(rt, genl_family_chain(i), family_list) {
if (++n < fams_to_skip)
continue;
if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).pid,
cb->nlh->nlmsg_seq, NLM_F_MULTI,
skb, CTRL_CMD_NEWFAMILY) < 0)
goto errout;
}
fams_to_skip = 0;
}
errout:
cb->args[0] = i;
cb->args[1] = n;
return skb->len;
}
static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
u32 pid, int seq, u8 cmd)
{
struct sk_buff *skb;
int err;
skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
if (skb == NULL)
return ERR_PTR(-ENOBUFS);
err = ctrl_fill_info(family, pid, seq, 0, skb, cmd);
if (err < 0) {
nlmsg_free(skb);
return ERR_PTR(err);
}
return skb;
}
static struct sk_buff *ctrl_build_mcgrp_msg(struct genl_multicast_group *grp,
u32 pid, int seq, u8 cmd)
{
struct sk_buff *skb;
int err;
skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
if (skb == NULL)
return ERR_PTR(-ENOBUFS);
err = ctrl_fill_mcgrp_info(grp, pid, seq, 0, skb, cmd);
if (err < 0) {
nlmsg_free(skb);
return ERR_PTR(err);
}
return skb;
}
static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
[CTRL_ATTR_FAMILY_ID] = { .type = NLA_U16 },
[CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
.len = GENL_NAMSIZ - 1 },
};
static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
{
struct sk_buff *msg;
struct genl_family *res = NULL;
int err = -EINVAL;
if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
res = genl_family_find_byid(id);
}
if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
char *name;
name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
res = genl_family_find_byname(name);
}
if (res == NULL) {
err = -ENOENT;
goto errout;
}
msg = ctrl_build_family_msg(res, info->snd_pid, info->snd_seq,
CTRL_CMD_NEWFAMILY);
if (IS_ERR(msg)) {
err = PTR_ERR(msg);
goto errout;
}
err = genlmsg_reply(msg, info);
errout:
return err;
}
static int genl_ctrl_event(int event, void *data)
{
struct sk_buff *msg;
if (genl_sock == NULL)
return 0;
switch (event) {
case CTRL_CMD_NEWFAMILY:
case CTRL_CMD_DELFAMILY:
msg = ctrl_build_family_msg(data, 0, 0, event);
if (IS_ERR(msg))
return PTR_ERR(msg);
genlmsg_multicast(msg, 0, GENL_ID_CTRL, GFP_KERNEL);
break;
case CTRL_CMD_NEWMCAST_GRP:
case CTRL_CMD_DELMCAST_GRP:
msg = ctrl_build_mcgrp_msg(data, 0, 0, event);
if (IS_ERR(msg))
return PTR_ERR(msg);
genlmsg_multicast(msg, 0, GENL_ID_CTRL, GFP_KERNEL);
break;
}
return 0;
}
static struct genl_ops genl_ctrl_ops = {
.cmd = CTRL_CMD_GETFAMILY,
.doit = ctrl_getfamily,
.dumpit = ctrl_dumpfamily,
.policy = ctrl_policy,
};
static struct genl_multicast_group notify_grp = {
.name = "notify",
};
static int __init genl_init(void)
{
int i, err;
for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
INIT_LIST_HEAD(&family_ht[i]);
err = genl_register_family(&genl_ctrl);
if (err < 0)
goto errout;
err = genl_register_ops(&genl_ctrl, &genl_ctrl_ops);
if (err < 0)
goto errout_register;
netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);
/* we'll bump the group number right afterwards */
genl_sock = netlink_kernel_create(&init_net, NETLINK_GENERIC, 0,
genl_rcv, &genl_mutex, THIS_MODULE);
if (genl_sock == NULL)
panic("GENL: Cannot initialize generic netlink\n");
err = genl_register_mc_group(&genl_ctrl, ¬ify_grp);
if (err < 0)
goto errout_register;
return 0;
errout_register:
genl_unregister_family(&genl_ctrl);
errout:
panic("GENL: Cannot register controller: %d\n", err);
}
subsys_initcall(genl_init);
EXPORT_SYMBOL(genl_sock);
EXPORT_SYMBOL(genl_register_ops);
EXPORT_SYMBOL(genl_unregister_ops);
EXPORT_SYMBOL(genl_register_family);
EXPORT_SYMBOL(genl_unregister_family);