// SPDX-License-Identifier: GPL-2.0 /* * NETLINK Generic Netlink Family * * Authors: Jamal Hadi Salim * Thomas Graf * Johannes Berg */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */ static DECLARE_RWSEM(cb_lock); atomic_t genl_sk_destructing_cnt = ATOMIC_INIT(0); DECLARE_WAIT_QUEUE_HEAD(genl_sk_destructing_waitq); void genl_lock(void) { mutex_lock(&genl_mutex); } EXPORT_SYMBOL(genl_lock); void genl_unlock(void) { mutex_unlock(&genl_mutex); } EXPORT_SYMBOL(genl_unlock); #ifdef CONFIG_LOCKDEP bool lockdep_genl_is_held(void) { return lockdep_is_held(&genl_mutex); } EXPORT_SYMBOL(lockdep_genl_is_held); #endif static void genl_lock_all(void) { down_write(&cb_lock); genl_lock(); } static void genl_unlock_all(void) { genl_unlock(); up_write(&cb_lock); } static DEFINE_IDR(genl_fam_idr); /* * 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. * Bit 1 is marked as already used since the drop-monitor code * abuses the API and thinks it can statically use group 1. * That group will typically conflict with other groups that * any proper users use. * Bit 16 is marked as used since it's used for generic netlink * and the code no longer marks pre-reserved IDs as used. * Bit 17 is marked as already used since the VFS quota code * also abused this API and relied on family == group ID, we * cater to that by giving it a static family and group ID. * Bit 18 is marked as already used since the PMCRAID driver * did the same thing as the VFS quota code (maybe copied?) */ static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) | BIT(GENL_ID_VFS_DQUOT) | BIT(GENL_ID_PMCRAID); static unsigned long *mc_groups = &mc_group_start; static unsigned long mc_groups_longs = 1; static int genl_ctrl_event(int event, const struct genl_family *family, const struct genl_multicast_group *grp, int grp_id); static const struct genl_family *genl_family_find_byid(unsigned int id) { return idr_find(&genl_fam_idr, id); } static const struct genl_family *genl_family_find_byname(char *name) { const struct genl_family *family; unsigned int id; idr_for_each_entry(&genl_fam_idr, family, id) if (strcmp(family->name, name) == 0) return family; return NULL; } static int genl_get_cmd_cnt(const struct genl_family *family) { return family->n_ops + family->n_small_ops; } static void genl_op_from_full(const struct genl_family *family, unsigned int i, struct genl_ops *op) { *op = family->ops[i]; } static int genl_get_cmd_full(u8 cmd, const struct genl_family *family, struct genl_ops *op) { int i; for (i = 0; i < family->n_ops; i++) if (family->ops[i].cmd == cmd) { genl_op_from_full(family, i, op); return 0; } return -ENOENT; } static void genl_op_from_small(const struct genl_family *family, unsigned int i, struct genl_ops *op) { memset(op, 0, sizeof(*op)); op->doit = family->small_ops[i].doit; op->dumpit = family->small_ops[i].dumpit; op->cmd = family->small_ops[i].cmd; op->internal_flags = family->small_ops[i].internal_flags; op->flags = family->small_ops[i].flags; op->validate = family->small_ops[i].validate; } static int genl_get_cmd_small(u8 cmd, const struct genl_family *family, struct genl_ops *op) { int i; for (i = 0; i < family->n_small_ops; i++) if (family->small_ops[i].cmd == cmd) { genl_op_from_small(family, i, op); return 0; } return -ENOENT; } static int genl_get_cmd(u8 cmd, const struct genl_family *family, struct genl_ops *op) { if (!genl_get_cmd_full(cmd, family, op)) return 0; return genl_get_cmd_small(cmd, family, op); } static void genl_get_cmd_by_index(unsigned int i, const struct genl_family *family, struct genl_ops *op) { if (i < family->n_ops) genl_op_from_full(family, i, op); else if (i < family->n_ops + family->n_small_ops) genl_op_from_small(family, i - family->n_ops, op); else WARN_ON_ONCE(1); } static int genl_allocate_reserve_groups(int n_groups, int *first_id) { unsigned long *new_groups; int start = 0; int i; int id; bool fits; do { if (start == 0) id = find_first_zero_bit(mc_groups, mc_groups_longs * BITS_PER_LONG); else id = find_next_zero_bit(mc_groups, mc_groups_longs * BITS_PER_LONG, start); fits = true; for (i = id; i < min_t(int, id + n_groups, mc_groups_longs * BITS_PER_LONG); i++) { if (test_bit(i, mc_groups)) { start = i; fits = false; break; } } if (id + n_groups > mc_groups_longs * BITS_PER_LONG) { unsigned long new_longs = mc_groups_longs + BITS_TO_LONGS(n_groups); size_t nlen = new_longs * sizeof(unsigned long); if (mc_groups == &mc_group_start) { new_groups = kzalloc(nlen, GFP_KERNEL); if (!new_groups) return -ENOMEM; mc_groups = new_groups; *mc_groups = mc_group_start; } else { new_groups = krealloc(mc_groups, nlen, GFP_KERNEL); if (!new_groups) return -ENOMEM; mc_groups = new_groups; for (i = 0; i < BITS_TO_LONGS(n_groups); i++) mc_groups[mc_groups_longs + i] = 0; } mc_groups_longs = new_longs; } } while (!fits); for (i = id; i < id + n_groups; i++) set_bit(i, mc_groups); *first_id = id; return 0; } static struct genl_family genl_ctrl; static int genl_validate_assign_mc_groups(struct genl_family *family) { int first_id; int n_groups = family->n_mcgrps; int err = 0, i; bool groups_allocated = false; if (!n_groups) return 0; for (i = 0; i < n_groups; i++) { const struct genl_multicast_group *grp = &family->mcgrps[i]; if (WARN_ON(grp->name[0] == '\0')) return -EINVAL; if (WARN_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL)) return -EINVAL; } /* special-case our own group and hacks */ if (family == &genl_ctrl) { first_id = GENL_ID_CTRL; BUG_ON(n_groups != 1); } else if (strcmp(family->name, "NET_DM") == 0) { first_id = 1; BUG_ON(n_groups != 1); } else if (family->id == GENL_ID_VFS_DQUOT) { first_id = GENL_ID_VFS_DQUOT; BUG_ON(n_groups != 1); } else if (family->id == GENL_ID_PMCRAID) { first_id = GENL_ID_PMCRAID; BUG_ON(n_groups != 1); } else { groups_allocated = true; err = genl_allocate_reserve_groups(n_groups, &first_id); if (err) return err; } family->mcgrp_offset = first_id; /* if still initializing, can't and don't need to realloc bitmaps */ if (!init_net.genl_sock) return 0; if (family->netnsok) { struct net *net; netlink_table_grab(); rcu_read_lock(); for_each_net_rcu(net) { err = __netlink_change_ngroups(net->genl_sock, mc_groups_longs * BITS_PER_LONG); if (err) { /* * No need to roll back, can only fail if * memory allocation fails and then the * number of _possible_ groups has been * increased on some sockets which is ok. */ break; } } rcu_read_unlock(); netlink_table_ungrab(); } else { err = netlink_change_ngroups(init_net.genl_sock, mc_groups_longs * BITS_PER_LONG); } if (groups_allocated && err) { for (i = 0; i < family->n_mcgrps; i++) clear_bit(family->mcgrp_offset + i, mc_groups); } return err; } static void genl_unregister_mc_groups(const struct genl_family *family) { struct net *net; int i; netlink_table_grab(); rcu_read_lock(); for_each_net_rcu(net) { for (i = 0; i < family->n_mcgrps; i++) __netlink_clear_multicast_users( net->genl_sock, family->mcgrp_offset + i); } rcu_read_unlock(); netlink_table_ungrab(); for (i = 0; i < family->n_mcgrps; i++) { int grp_id = family->mcgrp_offset + i; if (grp_id != 1) clear_bit(grp_id, mc_groups); genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, family, &family->mcgrps[i], grp_id); } } static int genl_validate_ops(const struct genl_family *family) { int i, j; if (WARN_ON(family->n_ops && !family->ops) || WARN_ON(family->n_small_ops && !family->small_ops)) return -EINVAL; for (i = 0; i < genl_get_cmd_cnt(family); i++) { struct genl_ops op; genl_get_cmd_by_index(i, family, &op); if (op.dumpit == NULL && op.doit == NULL) return -EINVAL; for (j = i + 1; j < genl_get_cmd_cnt(family); j++) { struct genl_ops op2; genl_get_cmd_by_index(j, family, &op2); if (op.cmd == op2.cmd) return -EINVAL; } } return 0; } /** * 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's ops, multicast groups and module pointer must already * be assigned. * * Return 0 on success or a negative error code. */ int genl_register_family(struct genl_family *family) { int err, i; int start = GENL_START_ALLOC, end = GENL_MAX_ID; err = genl_validate_ops(family); if (err) return err; genl_lock_all(); if (genl_family_find_byname(family->name)) { err = -EEXIST; goto errout_locked; } /* * Sadly, a few cases need to be special-cased * due to them having previously abused the API * and having used their family ID also as their * multicast group ID, so we use reserved IDs * for both to be sure we can do that mapping. */ if (family == &genl_ctrl) { /* and this needs to be special for initial family lookups */ start = end = GENL_ID_CTRL; } else if (strcmp(family->name, "pmcraid") == 0) { start = end = GENL_ID_PMCRAID; } else if (strcmp(family->name, "VFS_DQUOT") == 0) { start = end = GENL_ID_VFS_DQUOT; } family->id = idr_alloc_cyclic(&genl_fam_idr, family, start, end + 1, GFP_KERNEL); if (family->id < 0) { err = family->id; goto errout_locked; } err = genl_validate_assign_mc_groups(family); if (err) goto errout_remove; genl_unlock_all(); /* send all events */ genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0); for (i = 0; i < family->n_mcgrps; i++) genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family, &family->mcgrps[i], family->mcgrp_offset + i); return 0; errout_remove: idr_remove(&genl_fam_idr, family->id); errout_locked: genl_unlock_all(); return err; } EXPORT_SYMBOL(genl_register_family); /** * 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(const struct genl_family *family) { genl_lock_all(); if (!genl_family_find_byid(family->id)) { genl_unlock_all(); return -ENOENT; } genl_unregister_mc_groups(family); idr_remove(&genl_fam_idr, family->id); up_write(&cb_lock); wait_event(genl_sk_destructing_waitq, atomic_read(&genl_sk_destructing_cnt) == 0); genl_unlock(); genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0); return 0; } EXPORT_SYMBOL(genl_unregister_family); /** * genlmsg_put - Add generic netlink header to netlink message * @skb: socket buffer holding the message * @portid: netlink portid the message is addressed to * @seq: sequence number (usually the one of the sender) * @family: generic netlink family * @flags: netlink message flags * @cmd: generic netlink command * * Returns pointer to user specific header */ void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, const struct genl_family *family, int flags, u8 cmd) { struct nlmsghdr *nlh; struct genlmsghdr *hdr; nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN + family->hdrsize, flags); if (nlh == NULL) return NULL; hdr = nlmsg_data(nlh); hdr->cmd = cmd; hdr->version = family->version; hdr->reserved = 0; return (char *) hdr + GENL_HDRLEN; } EXPORT_SYMBOL(genlmsg_put); static struct genl_dumpit_info *genl_dumpit_info_alloc(void) { return kmalloc(sizeof(struct genl_dumpit_info), GFP_KERNEL); } static void genl_dumpit_info_free(const struct genl_dumpit_info *info) { kfree(info); } static struct nlattr ** genl_family_rcv_msg_attrs_parse(const struct genl_family *family, struct nlmsghdr *nlh, struct netlink_ext_ack *extack, const struct genl_ops *ops, int hdrlen, enum genl_validate_flags no_strict_flag) { enum netlink_validation validate = ops->validate & no_strict_flag ? NL_VALIDATE_LIBERAL : NL_VALIDATE_STRICT; struct nlattr **attrbuf; int err; if (!family->maxattr) return NULL; attrbuf = kmalloc_array(family->maxattr + 1, sizeof(struct nlattr *), GFP_KERNEL); if (!attrbuf) return ERR_PTR(-ENOMEM); err = __nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr, family->policy, validate, extack); if (err) { kfree(attrbuf); return ERR_PTR(err); } return attrbuf; } static void genl_family_rcv_msg_attrs_free(struct nlattr **attrbuf) { kfree(attrbuf); } struct genl_start_context { const struct genl_family *family; struct nlmsghdr *nlh; struct netlink_ext_ack *extack; const struct genl_ops *ops; int hdrlen; }; static int genl_start(struct netlink_callback *cb) { struct genl_start_context *ctx = cb->data; const struct genl_ops *ops = ctx->ops; struct genl_dumpit_info *info; struct nlattr **attrs = NULL; int rc = 0; if (ops->validate & GENL_DONT_VALIDATE_DUMP) goto no_attrs; if (ctx->nlh->nlmsg_len < nlmsg_msg_size(ctx->hdrlen)) return -EINVAL; attrs = genl_family_rcv_msg_attrs_parse(ctx->family, ctx->nlh, ctx->extack, ops, ctx->hdrlen, GENL_DONT_VALIDATE_DUMP_STRICT); if (IS_ERR(attrs)) return PTR_ERR(attrs); no_attrs: info = genl_dumpit_info_alloc(); if (!info) { genl_family_rcv_msg_attrs_free(attrs); return -ENOMEM; } info->family = ctx->family; info->op = *ops; info->attrs = attrs; cb->data = info; if (ops->start) { if (!ctx->family->parallel_ops) genl_lock(); rc = ops->start(cb); if (!ctx->family->parallel_ops) genl_unlock(); } if (rc) { genl_family_rcv_msg_attrs_free(info->attrs); genl_dumpit_info_free(info); cb->data = NULL; } return rc; } static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb) { const struct genl_ops *ops = &genl_dumpit_info(cb)->op; int rc; genl_lock(); rc = ops->dumpit(skb, cb); genl_unlock(); return rc; } static int genl_lock_done(struct netlink_callback *cb) { const struct genl_dumpit_info *info = genl_dumpit_info(cb); const struct genl_ops *ops = &info->op; int rc = 0; if (ops->done) { genl_lock(); rc = ops->done(cb); genl_unlock(); } genl_family_rcv_msg_attrs_free(info->attrs); genl_dumpit_info_free(info); return rc; } static int genl_parallel_done(struct netlink_callback *cb) { const struct genl_dumpit_info *info = genl_dumpit_info(cb); const struct genl_ops *ops = &info->op; int rc = 0; if (ops->done) rc = ops->done(cb); genl_family_rcv_msg_attrs_free(info->attrs); genl_dumpit_info_free(info); return rc; } static int genl_family_rcv_msg_dumpit(const struct genl_family *family, struct sk_buff *skb, struct nlmsghdr *nlh, struct netlink_ext_ack *extack, const struct genl_ops *ops, int hdrlen, struct net *net) { struct genl_start_context ctx; int err; if (!ops->dumpit) return -EOPNOTSUPP; ctx.family = family; ctx.nlh = nlh; ctx.extack = extack; ctx.ops = ops; ctx.hdrlen = hdrlen; if (!family->parallel_ops) { struct netlink_dump_control c = { .module = family->module, .data = &ctx, .start = genl_start, .dump = genl_lock_dumpit, .done = genl_lock_done, }; genl_unlock(); err = __netlink_dump_start(net->genl_sock, skb, nlh, &c); genl_lock(); } else { struct netlink_dump_control c = { .module = family->module, .data = &ctx, .start = genl_start, .dump = ops->dumpit, .done = genl_parallel_done, }; err = __netlink_dump_start(net->genl_sock, skb, nlh, &c); } return err; } static int genl_family_rcv_msg_doit(const struct genl_family *family, struct sk_buff *skb, struct nlmsghdr *nlh, struct netlink_ext_ack *extack, const struct genl_ops *ops, int hdrlen, struct net *net) { struct nlattr **attrbuf; struct genl_info info; int err; if (!ops->doit) return -EOPNOTSUPP; attrbuf = genl_family_rcv_msg_attrs_parse(family, nlh, extack, ops, hdrlen, GENL_DONT_VALIDATE_STRICT); if (IS_ERR(attrbuf)) return PTR_ERR(attrbuf); info.snd_seq = nlh->nlmsg_seq; info.snd_portid = NETLINK_CB(skb).portid; info.nlhdr = nlh; info.genlhdr = nlmsg_data(nlh); info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN; info.attrs = attrbuf; info.extack = extack; genl_info_net_set(&info, net); memset(&info.user_ptr, 0, sizeof(info.user_ptr)); if (family->pre_doit) { err = family->pre_doit(ops, skb, &info); if (err) goto out; } err = ops->doit(skb, &info); if (family->post_doit) family->post_doit(ops, skb, &info); out: genl_family_rcv_msg_attrs_free(attrbuf); return err; } static int genl_family_rcv_msg(const struct genl_family *family, struct sk_buff *skb, struct nlmsghdr *nlh, struct netlink_ext_ack *extack) { struct net *net = sock_net(skb->sk); struct genlmsghdr *hdr = nlmsg_data(nlh); struct genl_ops op; int hdrlen; /* this family doesn't exist in this netns */ if (!family->netnsok && !net_eq(net, &init_net)) return -ENOENT; hdrlen = GENL_HDRLEN + family->hdrsize; if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen)) return -EINVAL; if (genl_get_cmd(hdr->cmd, family, &op)) return -EOPNOTSUPP; if ((op.flags & GENL_ADMIN_PERM) && !netlink_capable(skb, CAP_NET_ADMIN)) return -EPERM; if ((op.flags & GENL_UNS_ADMIN_PERM) && !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN)) return -EPERM; if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) return genl_family_rcv_msg_dumpit(family, skb, nlh, extack, &op, hdrlen, net); else return genl_family_rcv_msg_doit(family, skb, nlh, extack, &op, hdrlen, net); } static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, struct netlink_ext_ack *extack) { const struct genl_family *family; int err; family = genl_family_find_byid(nlh->nlmsg_type); if (family == NULL) return -ENOENT; if (!family->parallel_ops) genl_lock(); err = genl_family_rcv_msg(family, skb, nlh, extack); if (!family->parallel_ops) genl_unlock(); return err; } static void genl_rcv(struct sk_buff *skb) { down_read(&cb_lock); netlink_rcv_skb(skb, &genl_rcv_msg); up_read(&cb_lock); } /************************************************************************** * Controller **************************************************************************/ static struct genl_family genl_ctrl; static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq, u32 flags, struct sk_buff *skb, u8 cmd) { void *hdr; hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd); if (hdr == NULL) return -1; if (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)) goto nla_put_failure; if (genl_get_cmd_cnt(family)) { struct nlattr *nla_ops; int i; nla_ops = nla_nest_start_noflag(skb, CTRL_ATTR_OPS); if (nla_ops == NULL) goto nla_put_failure; for (i = 0; i < genl_get_cmd_cnt(family); i++) { struct nlattr *nest; struct genl_ops op; u32 op_flags; genl_get_cmd_by_index(i, family, &op); op_flags = op.flags; if (op.dumpit) op_flags |= GENL_CMD_CAP_DUMP; if (op.doit) op_flags |= GENL_CMD_CAP_DO; if (family->policy) op_flags |= GENL_CMD_CAP_HASPOL; nest = nla_nest_start_noflag(skb, i + 1); if (nest == NULL) goto nla_put_failure; if (nla_put_u32(skb, CTRL_ATTR_OP_ID, op.cmd) || nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags)) goto nla_put_failure; nla_nest_end(skb, nest); } nla_nest_end(skb, nla_ops); } if (family->n_mcgrps) { struct nlattr *nla_grps; int i; nla_grps = nla_nest_start_noflag(skb, CTRL_ATTR_MCAST_GROUPS); if (nla_grps == NULL) goto nla_put_failure; for (i = 0; i < family->n_mcgrps; i++) { struct nlattr *nest; const struct genl_multicast_group *grp; grp = &family->mcgrps[i]; nest = nla_nest_start_noflag(skb, i + 1); if (nest == NULL) goto nla_put_failure; if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, family->mcgrp_offset + i) || nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME, grp->name)) goto nla_put_failure; nla_nest_end(skb, nest); } nla_nest_end(skb, nla_grps); } genlmsg_end(skb, hdr); return 0; nla_put_failure: genlmsg_cancel(skb, hdr); return -EMSGSIZE; } static int ctrl_fill_mcgrp_info(const struct genl_family *family, const struct genl_multicast_group *grp, int grp_id, u32 portid, u32 seq, u32 flags, struct sk_buff *skb, u8 cmd) { void *hdr; struct nlattr *nla_grps; struct nlattr *nest; hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd); if (hdr == NULL) return -1; if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) || nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id)) goto nla_put_failure; nla_grps = nla_nest_start_noflag(skb, CTRL_ATTR_MCAST_GROUPS); if (nla_grps == NULL) goto nla_put_failure; nest = nla_nest_start_noflag(skb, 1); if (nest == NULL) goto nla_put_failure; if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) || nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME, grp->name)) goto nla_put_failure; nla_nest_end(skb, nest); nla_nest_end(skb, nla_grps); genlmsg_end(skb, hdr); return 0; nla_put_failure: genlmsg_cancel(skb, hdr); return -EMSGSIZE; } static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb) { int n = 0; struct genl_family *rt; struct net *net = sock_net(skb->sk); int fams_to_skip = cb->args[0]; unsigned int id; idr_for_each_entry(&genl_fam_idr, rt, id) { if (!rt->netnsok && !net_eq(net, &init_net)) continue; if (n++ < fams_to_skip) continue; if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq, NLM_F_MULTI, skb, CTRL_CMD_NEWFAMILY) < 0) { n--; break; } } cb->args[0] = n; return skb->len; } static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family, u32 portid, 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, portid, seq, 0, skb, cmd); if (err < 0) { nlmsg_free(skb); return ERR_PTR(err); } return skb; } static struct sk_buff * ctrl_build_mcgrp_msg(const struct genl_family *family, const struct genl_multicast_group *grp, int grp_id, u32 portid, 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(family, grp, grp_id, portid, 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; const 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); err = -ENOENT; } if (info->attrs[CTRL_ATTR_FAMILY_NAME]) { char *name; name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]); res = genl_family_find_byname(name); #ifdef CONFIG_MODULES if (res == NULL) { genl_unlock(); up_read(&cb_lock); request_module("net-pf-%d-proto-%d-family-%s", PF_NETLINK, NETLINK_GENERIC, name); down_read(&cb_lock); genl_lock(); res = genl_family_find_byname(name); } #endif err = -ENOENT; } if (res == NULL) return err; if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) { /* family doesn't exist here */ return -ENOENT; } msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq, CTRL_CMD_NEWFAMILY); if (IS_ERR(msg)) return PTR_ERR(msg); return genlmsg_reply(msg, info); } static int genl_ctrl_event(int event, const struct genl_family *family, const struct genl_multicast_group *grp, int grp_id) { struct sk_buff *msg; /* genl is still initialising */ if (!init_net.genl_sock) return 0; switch (event) { case CTRL_CMD_NEWFAMILY: case CTRL_CMD_DELFAMILY: WARN_ON(grp); msg = ctrl_build_family_msg(family, 0, 0, event); break; case CTRL_CMD_NEWMCAST_GRP: case CTRL_CMD_DELMCAST_GRP: BUG_ON(!grp); msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event); break; default: return -EINVAL; } if (IS_ERR(msg)) return PTR_ERR(msg); if (!family->netnsok) { genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0, 0, GFP_KERNEL); } else { rcu_read_lock(); genlmsg_multicast_allns(&genl_ctrl, msg, 0, 0, GFP_ATOMIC); rcu_read_unlock(); } return 0; } struct ctrl_dump_policy_ctx { struct netlink_policy_dump_state *state; u16 fam_id; }; static int ctrl_dumppolicy(struct sk_buff *skb, struct netlink_callback *cb) { struct ctrl_dump_policy_ctx *ctx = (void *)cb->ctx; const struct genl_family *rt; int err; BUILD_BUG_ON(sizeof(*ctx) > sizeof(cb->ctx)); if (!ctx->fam_id) { struct nlattr *tb[CTRL_ATTR_MAX + 1]; err = genlmsg_parse(cb->nlh, &genl_ctrl, tb, genl_ctrl.maxattr, genl_ctrl.policy, cb->extack); if (err) return err; if (!tb[CTRL_ATTR_FAMILY_ID] && !tb[CTRL_ATTR_FAMILY_NAME]) return -EINVAL; if (tb[CTRL_ATTR_FAMILY_ID]) { ctx->fam_id = nla_get_u16(tb[CTRL_ATTR_FAMILY_ID]); } else { rt = genl_family_find_byname( nla_data(tb[CTRL_ATTR_FAMILY_NAME])); if (!rt) return -ENOENT; ctx->fam_id = rt->id; } } rt = genl_family_find_byid(ctx->fam_id); if (!rt) return -ENOENT; if (!rt->policy) return -ENODATA; err = netlink_policy_dump_start(rt->policy, rt->maxattr, &ctx->state); if (err) return err; while (netlink_policy_dump_loop(ctx->state)) { void *hdr; struct nlattr *nest; hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq, &genl_ctrl, NLM_F_MULTI, CTRL_CMD_GETPOLICY); if (!hdr) goto nla_put_failure; if (nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, rt->id)) goto nla_put_failure; nest = nla_nest_start(skb, CTRL_ATTR_POLICY); if (!nest) goto nla_put_failure; if (netlink_policy_dump_write(skb, ctx->state)) goto nla_put_failure; nla_nest_end(skb, nest); genlmsg_end(skb, hdr); continue; nla_put_failure: genlmsg_cancel(skb, hdr); break; } return skb->len; } static int ctrl_dumppolicy_done(struct netlink_callback *cb) { struct ctrl_dump_policy_ctx *ctx = (void *)cb->ctx; netlink_policy_dump_free(ctx->state); return 0; } static const struct genl_ops genl_ctrl_ops[] = { { .cmd = CTRL_CMD_GETFAMILY, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, .doit = ctrl_getfamily, .dumpit = ctrl_dumpfamily, }, { .cmd = CTRL_CMD_GETPOLICY, .dumpit = ctrl_dumppolicy, .done = ctrl_dumppolicy_done, }, }; static const struct genl_multicast_group genl_ctrl_groups[] = { { .name = "notify", }, }; static struct genl_family genl_ctrl __ro_after_init = { .module = THIS_MODULE, .ops = genl_ctrl_ops, .n_ops = ARRAY_SIZE(genl_ctrl_ops), .mcgrps = genl_ctrl_groups, .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups), .id = GENL_ID_CTRL, .name = "nlctrl", .version = 0x2, .maxattr = CTRL_ATTR_MAX, .policy = ctrl_policy, .netnsok = true, }; static int __net_init genl_pernet_init(struct net *net) { struct netlink_kernel_cfg cfg = { .input = genl_rcv, .flags = NL_CFG_F_NONROOT_RECV, }; /* we'll bump the group number right afterwards */ net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg); if (!net->genl_sock && net_eq(net, &init_net)) panic("GENL: Cannot initialize generic netlink\n"); if (!net->genl_sock) return -ENOMEM; return 0; } static void __net_exit genl_pernet_exit(struct net *net) { netlink_kernel_release(net->genl_sock); net->genl_sock = NULL; } static struct pernet_operations genl_pernet_ops = { .init = genl_pernet_init, .exit = genl_pernet_exit, }; static int __init genl_init(void) { int err; err = genl_register_family(&genl_ctrl); if (err < 0) goto problem; err = register_pernet_subsys(&genl_pernet_ops); if (err) goto problem; return 0; problem: panic("GENL: Cannot register controller: %d\n", err); } core_initcall(genl_init); static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group, gfp_t flags) { struct sk_buff *tmp; struct net *net, *prev = NULL; bool delivered = false; int err; for_each_net_rcu(net) { if (prev) { tmp = skb_clone(skb, flags); if (!tmp) { err = -ENOMEM; goto error; } err = nlmsg_multicast(prev->genl_sock, tmp, portid, group, flags); if (!err) delivered = true; else if (err != -ESRCH) goto error; } prev = net; } err = nlmsg_multicast(prev->genl_sock, skb, portid, group, flags); if (!err) delivered = true; else if (err != -ESRCH) return err; return delivered ? 0 : -ESRCH; error: kfree_skb(skb); return err; } int genlmsg_multicast_allns(const struct genl_family *family, struct sk_buff *skb, u32 portid, unsigned int group, gfp_t flags) { if (WARN_ON_ONCE(group >= family->n_mcgrps)) return -EINVAL; group = family->mcgrp_offset + group; return genlmsg_mcast(skb, portid, group, flags); } EXPORT_SYMBOL(genlmsg_multicast_allns); void genl_notify(const struct genl_family *family, struct sk_buff *skb, struct genl_info *info, u32 group, gfp_t flags) { struct net *net = genl_info_net(info); struct sock *sk = net->genl_sock; int report = 0; if (info->nlhdr) report = nlmsg_report(info->nlhdr); if (WARN_ON_ONCE(group >= family->n_mcgrps)) return; group = family->mcgrp_offset + group; nlmsg_notify(sk, skb, info->snd_portid, group, report, flags); } EXPORT_SYMBOL(genl_notify);