From bb9b18fb55b03477fe5bdd3e97245d6d4d3dee4f Mon Sep 17 00:00:00 2001 From: Thomas Graf Date: Sat, 30 Nov 2013 13:21:30 +0100 Subject: genl: Add genlmsg_new_unicast() for unicast message allocation Allocates a new sk_buff large enough to cover the specified payload plus required Netlink headers. Will check receiving socket for memory mapped i/o capability and use it if enabled. Will fall back to non-mapped skb if message size exceeds the frame size of the ring. Signed-of-by: Thomas Graf Reviewed-by: Daniel Borkmann Signed-off-by: Jesse Gross --- net/netlink/genetlink.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'net/netlink') diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c index 4518a57aa5fe..85bf42e2a943 100644 --- a/net/netlink/genetlink.c +++ b/net/netlink/genetlink.c @@ -453,6 +453,26 @@ int genl_unregister_family(struct genl_family *family) } EXPORT_SYMBOL(genl_unregister_family); +/** + * genlmsg_new_unicast - Allocate generic netlink message for unicast + * @payload: size of the message payload + * @info: information on destination + * @flags: the type of memory to allocate + * + * Allocates a new sk_buff large enough to cover the specified payload + * plus required Netlink headers. Will check receiving socket for + * memory mapped i/o capability and use it if enabled. Will fall back + * to non-mapped skb if message size exceeds the frame size of the ring. + */ +struct sk_buff *genlmsg_new_unicast(size_t payload, struct genl_info *info, + gfp_t flags) +{ + size_t len = nlmsg_total_size(genlmsg_total_size(payload)); + + return netlink_alloc_skb(info->dst_sk, len, info->snd_portid, flags); +} +EXPORT_SYMBOL_GPL(genlmsg_new_unicast); + /** * genlmsg_put - Add generic netlink header to netlink message * @skb: socket buffer holding the message @@ -593,6 +613,7 @@ static int genl_family_rcv_msg(struct genl_family *family, info.genlhdr = nlmsg_data(nlh); info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN; info.attrs = attrbuf; + info.dst_sk = skb->sk; genl_info_net_set(&info, net); memset(&info.user_ptr, 0, sizeof(info.user_ptr)); -- cgit v1.2.3 From aae9f0e22c07f6b97752741156ac0b3637d37a1a Mon Sep 17 00:00:00 2001 From: Thomas Graf Date: Sat, 30 Nov 2013 13:21:31 +0100 Subject: netlink: Avoid netlink mmap alloc if msg size exceeds frame size An insufficent ring frame size configuration can lead to an unnecessary skb allocation for every Netlink message. Check frame size before taking the queue lock and allocating the skb and re-check with lock to be safe. Signed-off-by: Thomas Graf Reviewed-by: Daniel Borkmann Signed-off-by: Jesse Gross --- net/netlink/af_netlink.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'net/netlink') diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index bca50b95c182..64334893c61c 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -1769,6 +1769,9 @@ struct sk_buff *netlink_alloc_skb(struct sock *ssk, unsigned int size, if (ring->pg_vec == NULL) goto out_put; + if (ring->frame_size - NL_MMAP_HDRLEN < size) + goto out_put; + skb = alloc_skb_head(gfp_mask); if (skb == NULL) goto err1; @@ -1778,6 +1781,7 @@ struct sk_buff *netlink_alloc_skb(struct sock *ssk, unsigned int size, if (ring->pg_vec == NULL) goto out_free; + /* check again under lock */ maxlen = ring->frame_size - NL_MMAP_HDRLEN; if (maxlen < size) goto out_free; -- cgit v1.2.3