From 2dbba6f773d1e1e4c78f03b0dbf19790d9017693 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Wed, 18 Jul 2007 15:47:52 -0700 Subject: [PATCH] [GENETLINK]: Dynamic multicast groups. Introduce API to dynamically register and unregister multicast groups. Signed-off-by: Johannes Berg Acked-by: Patrick McHardy Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller --- include/linux/genetlink.h | 13 +++ include/net/genetlink.h | 22 ++++ net/netlink/genetlink.c | 235 ++++++++++++++++++++++++++++++++++++-- 3 files changed, 263 insertions(+), 7 deletions(-) diff --git a/include/linux/genetlink.h b/include/linux/genetlink.h index f7a93770e1be..7da02c93002b 100644 --- a/include/linux/genetlink.h +++ b/include/linux/genetlink.h @@ -39,6 +39,9 @@ enum { CTRL_CMD_NEWOPS, CTRL_CMD_DELOPS, CTRL_CMD_GETOPS, + CTRL_CMD_NEWMCAST_GRP, + CTRL_CMD_DELMCAST_GRP, + CTRL_CMD_GETMCAST_GRP, /* unused */ __CTRL_CMD_MAX, }; @@ -52,6 +55,7 @@ enum { CTRL_ATTR_HDRSIZE, CTRL_ATTR_MAXATTR, CTRL_ATTR_OPS, + CTRL_ATTR_MCAST_GROUPS, __CTRL_ATTR_MAX, }; @@ -66,4 +70,13 @@ enum { #define CTRL_ATTR_OP_MAX (__CTRL_ATTR_OP_MAX - 1) +enum { + CTRL_ATTR_MCAST_GRP_UNSPEC, + CTRL_ATTR_MCAST_GRP_NAME, + CTRL_ATTR_MCAST_GRP_ID, + __CTRL_ATTR_MCAST_GRP_MAX, +}; + +#define CTRL_ATTR_MCAST_GRP_MAX (__CTRL_ATTR_MCAST_GRP_MAX - 1) + #endif /* __LINUX_GENERIC_NETLINK_H */ diff --git a/include/net/genetlink.h b/include/net/genetlink.h index b6eaca122db8..decdda546829 100644 --- a/include/net/genetlink.h +++ b/include/net/genetlink.h @@ -4,6 +4,22 @@ #include #include +/** + * struct genl_multicast_group - generic netlink multicast group + * @name: name of the multicast group, names are per-family + * @id: multicast group ID, assigned by the core, to use with + * genlmsg_multicast(). + * @list: list entry for linking + * @family: pointer to family, need not be set before registering + */ +struct genl_multicast_group +{ + struct genl_family *family; /* private */ + struct list_head list; /* private */ + char name[GENL_NAMSIZ]; + u32 id; +}; + /** * struct genl_family - generic netlink family * @id: protocol family idenfitier @@ -14,6 +30,7 @@ * @attrbuf: buffer to store parsed attributes * @ops_list: list of all assigned operations * @family_list: family list + * @mcast_groups: multicast groups list */ struct genl_family { @@ -25,6 +42,7 @@ struct genl_family struct nlattr ** attrbuf; /* private */ struct list_head ops_list; /* private */ struct list_head family_list; /* private */ + struct list_head mcast_groups; /* private */ }; /** @@ -73,6 +91,10 @@ extern int genl_register_family(struct genl_family *family); extern int genl_unregister_family(struct genl_family *family); extern int genl_register_ops(struct genl_family *, struct genl_ops *ops); extern int genl_unregister_ops(struct genl_family *, struct genl_ops *ops); +extern int genl_register_mc_group(struct genl_family *family, + struct genl_multicast_group *grp); +extern void genl_unregister_mc_group(struct genl_family *family, + struct genl_multicast_group *grp); extern struct sock *genl_sock; diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c index b9ab62f938d0..e146531faf1d 100644 --- a/net/netlink/genetlink.c +++ b/net/netlink/genetlink.c @@ -3,6 +3,7 @@ * * Authors: Jamal Hadi Salim * Thomas Graf + * Johannes Berg */ #include @@ -13,6 +14,7 @@ #include #include #include +#include #include #include @@ -42,6 +44,16 @@ static void genl_unlock(void) #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); @@ -116,6 +128,114 @@ static inline u16 genl_generate_id(void) 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, + sizeof(unsigned long) * NETLINK_GENERIC); + 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 0; +} +EXPORT_SYMBOL(genl_register_mc_group); + +/** + * 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) +{ + BUG_ON(grp->family != family); + genl_lock(); + 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_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 @@ -216,6 +336,7 @@ int genl_register_family(struct genl_family *family) goto errout; INIT_LIST_HEAD(&family->ops_list); + INIT_LIST_HEAD(&family->mcast_groups); genl_lock(); @@ -275,6 +396,8 @@ int genl_unregister_family(struct genl_family *family) { struct genl_family *rc; + genl_unregister_mc_groups(family); + genl_lock(); list_for_each_entry(rc, genl_family_chain(family->id), family_list) { @@ -410,6 +533,67 @@ static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq, 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: + return genlmsg_cancel(skb, hdr); +} + +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: @@ -453,8 +637,8 @@ static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb) return skb->len; } -static struct sk_buff *ctrl_build_msg(struct genl_family *family, u32 pid, - int seq, u8 cmd) +static struct sk_buff *ctrl_build_family_msg(struct genl_family *family, + u32 pid, int seq, u8 cmd) { struct sk_buff *skb; int err; @@ -472,6 +656,25 @@ static struct sk_buff *ctrl_build_msg(struct genl_family *family, u32 pid, 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, @@ -501,8 +704,8 @@ static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info) goto errout; } - msg = ctrl_build_msg(res, info->snd_pid, info->snd_seq, - CTRL_CMD_NEWFAMILY); + 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; @@ -523,7 +726,15 @@ static int genl_ctrl_event(int event, void *data) switch (event) { case CTRL_CMD_NEWFAMILY: case CTRL_CMD_DELFAMILY: - msg = ctrl_build_msg(data, 0, 0, event); + 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); @@ -541,6 +752,10 @@ static struct genl_ops genl_ctrl_ops = { .policy = ctrl_policy, }; +static struct genl_multicast_group notify_grp = { + .name = "notify", +}; + static int __init genl_init(void) { int i, err; @@ -557,11 +772,17 @@ static int __init genl_init(void) goto errout_register; netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV); - genl_sock = netlink_kernel_create(NETLINK_GENERIC, GENL_MAX_ID, - genl_rcv, NULL, THIS_MODULE); + + /* we'll bump the group number right afterwards */ + genl_sock = netlink_kernel_create(NETLINK_GENERIC, 0, genl_rcv, + NULL, 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: -- GitLab