From 2a94fe48f32ccf7321450a2cc07f2b724a444e5b Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Tue, 19 Nov 2013 15:19:39 +0100 Subject: genetlink: make multicast groups const, prevent abuse Register generic netlink multicast groups as an array with the family and give them contiguous group IDs. Then instead of passing the global group ID to the various functions that send messages, pass the ID relative to the family - for most families that's just 0 because the only have one group. This avoids the list_head and ID in each group, adding a new field for the mcast group ID offset to the family. At the same time, this allows us to prevent abusing groups again like the quota and dropmon code did, since we can now check that a family only uses a group it owns. Signed-off-by: Johannes Berg Signed-off-by: David S. Miller --- include/net/genetlink.h | 48 +++++++++++++++++++++++++++++++----------------- 1 file changed, 31 insertions(+), 17 deletions(-) (limited to 'include/net') diff --git a/include/net/genetlink.h b/include/net/genetlink.h index 60aef0d..ace4abf 100644 --- a/include/net/genetlink.h +++ b/include/net/genetlink.h @@ -10,14 +10,9 @@ /** * 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 */ struct genl_multicast_group { - struct list_head list; /* private */ char name[GENL_NAMSIZ]; - u32 id; }; struct genl_ops; @@ -38,7 +33,9 @@ struct genl_info; * undo operations done by pre_doit, for example release locks * @attrbuf: buffer to store parsed attributes * @family_list: family list - * @mcast_groups: multicast groups list + * @mcgrps: multicast groups used by this family (private) + * @n_mcgrps: number of multicast groups (private) + * @mcgrp_offset: starting number of multicast group IDs in this family * @ops: the operations supported by this family (private) * @n_ops: number of operations supported by this family (private) */ @@ -58,9 +55,11 @@ struct genl_family { struct genl_info *info); struct nlattr ** attrbuf; /* private */ const struct genl_ops * ops; /* private */ + const struct genl_multicast_group *mcgrps; /* private */ unsigned int n_ops; /* private */ + unsigned int n_mcgrps; /* private */ + unsigned int mcgrp_offset; /* private */ struct list_head family_list; /* private */ - struct list_head mcast_groups; /* private */ struct module *module; }; @@ -150,22 +149,30 @@ static inline int genl_register_family(struct genl_family *family) * * Return 0 on success or a negative error code. */ -static inline int _genl_register_family_with_ops(struct genl_family *family, - const struct genl_ops *ops, - size_t n_ops) +static inline int +_genl_register_family_with_ops_grps(struct genl_family *family, + const struct genl_ops *ops, size_t n_ops, + const struct genl_multicast_group *mcgrps, + size_t n_mcgrps) { family->module = THIS_MODULE; family->ops = ops; family->n_ops = n_ops; + family->mcgrps = mcgrps; + family->n_mcgrps = n_mcgrps; return __genl_register_family(family); } -#define genl_register_family_with_ops(family, ops) \ - _genl_register_family_with_ops((family), (ops), ARRAY_SIZE(ops)) +#define genl_register_family_with_ops(family, ops) \ + _genl_register_family_with_ops_grps((family), \ + (ops), ARRAY_SIZE(ops), \ + NULL, 0) +#define genl_register_family_with_ops_groups(family, ops, grps) \ + _genl_register_family_with_ops_grps((family), \ + (ops), ARRAY_SIZE(ops), \ + (grps), ARRAY_SIZE(grps)) int genl_unregister_family(struct genl_family *family); -int genl_register_mc_group(struct genl_family *family, - struct genl_multicast_group *grp); void genl_notify(struct genl_family *family, struct sk_buff *skb, struct net *net, u32 portid, u32 group, struct nlmsghdr *nlh, gfp_t flags); @@ -251,13 +258,16 @@ static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr) * @net: the net namespace * @skb: netlink message as socket buffer * @portid: own netlink portid to avoid sending to yourself - * @group: multicast group id + * @group: offset of multicast group in groups array * @flags: allocation flags */ static inline int genlmsg_multicast_netns(struct genl_family *family, struct net *net, struct sk_buff *skb, u32 portid, unsigned int group, gfp_t flags) { + if (group >= family->n_mcgrps) + return -EINVAL; + group = family->mcgrp_offset + group; return nlmsg_multicast(net->genl_sock, skb, portid, group, flags); } @@ -266,13 +276,16 @@ static inline int genlmsg_multicast_netns(struct genl_family *family, * @family: the generic netlink family * @skb: netlink message as socket buffer * @portid: own netlink portid to avoid sending to yourself - * @group: multicast group id + * @group: offset of multicast group in groups array * @flags: allocation flags */ static inline int genlmsg_multicast(struct genl_family *family, struct sk_buff *skb, u32 portid, unsigned int group, gfp_t flags) { + if (group >= family->n_mcgrps) + return -EINVAL; + group = family->mcgrp_offset + group; return genlmsg_multicast_netns(family, &init_net, skb, portid, group, flags); } @@ -282,7 +295,7 @@ static inline int genlmsg_multicast(struct genl_family *family, * @family: the generic netlink family * @skb: netlink message as socket buffer * @portid: own netlink portid to avoid sending to yourself - * @group: multicast group id + * @group: offset of multicast group in groups array * @flags: allocation flags * * This function must hold the RTNL or rcu_read_lock(). @@ -365,6 +378,7 @@ static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags) * @net: the network namespace to report the error to * @portid: the PORTID of a process that we want to skip (if any) * @group: the broadcast group that will notice the error + * (this is the offset of the multicast group in the groups array) * @code: error code, must be negative (as usual in kernelspace) * * This function returns the number of broadcast listeners that have set the -- cgit v1.1