/* * 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);