diff options
Diffstat (limited to 'net/netlink/genetlink.c')
| -rw-r--r-- | net/netlink/genetlink.c | 579 |
1 files changed, 579 insertions, 0 deletions
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c new file mode 100644 index 00000000000000..287cfcc56951a8 --- /dev/null +++ b/net/netlink/genetlink.c @@ -0,0 +1,579 @@ +/* + * NETLINK Generic Netlink Family + * + * Authors: Jamal Hadi Salim + * Thomas Graf <tgraf@suug.ch> + */ + +#include <linux/config.h> +#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 <net/sock.h> +#include <net/genetlink.h> + +struct sock *genl_sock = NULL; + +static DECLARE_MUTEX(genl_sem); /* serialization of message processing */ + +static void genl_lock(void) +{ + down(&genl_sem); +} + +static int genl_trylock(void) +{ + return down_trylock(&genl_sem); +} + +static void genl_unlock(void) +{ + up(&genl_sem); + + if (genl_sock && genl_sock->sk_receive_queue.qlen) + genl_sock->sk_data_ready(genl_sock, 0); +} + +#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]; + +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; +} + +/** + * 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; + } + + 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); + + 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 (!try_module_get(family->owner)) { + err = -EBUSY; + 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; + } + } 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(); + + 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(); + + module_put(family->owner); + kfree(family->attrbuf); + genl_ctrl_event(CTRL_CMD_DELFAMILY, family); + return 0; + } + + genl_unlock(); + + return -ENOENT; +} + +static inline int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, + int *errp) +{ + struct genl_ops *ops; + struct genl_family *family; + struct genl_info info; + struct genlmsghdr *hdr = nlmsg_data(nlh); + int hdrlen, err = -EINVAL; + + if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) + goto ignore; + + if (nlh->nlmsg_type < NLMSG_MIN_TYPE) + goto ignore; + + family = genl_family_find_byid(nlh->nlmsg_type); + if (family == NULL) { + err = -ENOENT; + goto errout; + } + + hdrlen = GENL_HDRLEN + family->hdrsize; + if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen)) + goto errout; + + ops = genl_get_cmd(hdr->cmd, family); + if (ops == NULL) { + err = -EOPNOTSUPP; + goto errout; + } + + if ((ops->flags & GENL_ADMIN_PERM) && security_netlink_recv(skb)) { + err = -EPERM; + goto errout; + } + + if (nlh->nlmsg_flags & NLM_F_DUMP) { + if (ops->dumpit == NULL) { + err = -EOPNOTSUPP; + goto errout; + } + + *errp = err = netlink_dump_start(genl_sock, skb, nlh, + ops->dumpit, NULL); + if (err == 0) + skb_pull(skb, min(NLMSG_ALIGN(nlh->nlmsg_len), + skb->len)); + return -1; + } + + if (ops->doit == NULL) { + err = -EOPNOTSUPP; + goto errout; + } + + if (family->attrbuf) { + err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr, + ops->policy); + if (err < 0) + goto errout; + } + + 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; + + *errp = err = ops->doit(skb, &info); + return err; + +ignore: + return 0; + +errout: + *errp = err; + return -1; +} + +static void genl_rcv(struct sock *sk, int len) +{ + unsigned int qlen = 0; + + do { + if (genl_trylock()) + return; + netlink_run_queue(sk, &qlen, &genl_rcv_msg); + genl_unlock(); + } while (qlen && genl_sock && genl_sock->sk_receive_queue.qlen); +} + +/************************************************************************** + * Controller + **************************************************************************/ + +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_ID_CTRL, 0, flags, cmd, + family->version); + 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); + + return genlmsg_end(skb, hdr); + +nla_put_failure: + return genlmsg_cancel(skb, hdr); +} + +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_msg(struct genl_family *family, u32 pid, + int seq, int cmd) +{ + struct sk_buff *skb; + int err; + + skb = nlmsg_new(NLMSG_GOODSIZE); + 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 nla_policy ctrl_policy[CTRL_ATTR_MAX+1] __read_mostly = { + [CTRL_ATTR_FAMILY_ID] = { .type = NLA_U16 }, + [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_STRING }, +}; + +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[GENL_NAMSIZ]; + + if (nla_strlcpy(name, info->attrs[CTRL_ATTR_FAMILY_NAME], + GENL_NAMSIZ) >= GENL_NAMSIZ) + goto errout; + + res = genl_family_find_byname(name); + } + + if (res == NULL) { + err = -ENOENT; + goto errout; + } + + msg = ctrl_build_msg(res, info->snd_pid, info->snd_seq, + CTRL_CMD_NEWFAMILY); + if (IS_ERR(msg)) { + err = PTR_ERR(msg); + goto errout; + } + + err = genlmsg_unicast(msg, info->snd_pid); +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_msg(data, 0, 0, event); + if (IS_ERR(msg)) + return PTR_ERR(msg); + + genlmsg_multicast(msg, 0, GENL_ID_CTRL); + 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_family genl_ctrl = { + .id = GENL_ID_CTRL, + .name = "nlctrl", + .version = 0x1, + .maxattr = CTRL_ATTR_MAX, + .owner = THIS_MODULE, +}; + +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); + genl_sock = netlink_kernel_create(NETLINK_GENERIC, GENL_MAX_ID, + genl_rcv, THIS_MODULE); + if (genl_sock == NULL) { + panic("GENL: Cannot initialize generic netlink\n"); + return -ENOMEM; + } + + return 0; + +errout_register: + genl_unregister_family(&genl_ctrl); +errout: + panic("GENL: Cannot register controller: %d\n", err); + return 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); |