diff options
author | Jerry Chu <hkchu@google.com> | 2012-08-31 12:29:11 +0000 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2012-08-31 20:02:18 -0400 |
commit | 1046716368979dee857a2b8a91c4a8833f21b9cb (patch) | |
tree | fdda70278e6fa56c27d242fb1a0ec9b7e3e81d38 /net/ipv4/tcp_fastopen.c | |
parent | 2a35cfa591ac63f17815c2d9432b799e37527980 (diff) |
tcp: TCP Fast Open Server - header & support functions
This patch adds all the necessary data structure and support
functions to implement TFO server side. It also documents a number
of flags for the sysctl_tcp_fastopen knob, and adds a few Linux
extension MIBs.
In addition, it includes the following:
1. a new TCP_FASTOPEN socket option an application must call to
supply a max backlog allowed in order to enable TFO on its listener.
2. A number of key data structures:
"fastopen_rsk" in tcp_sock - for a big socket to access its
request_sock for retransmission and ack processing purpose. It is
non-NULL iff 3WHS not completed.
"fastopenq" in request_sock_queue - points to a per Fast Open
listener data structure "fastopen_queue" to keep track of qlen (# of
outstanding Fast Open requests) and max_qlen, among other things.
"listener" in tcp_request_sock - to point to the original listener
for book-keeping purpose, i.e., to maintain qlen against max_qlen
as part of defense against IP spoofing attack.
3. various data structure and functions, many in tcp_fastopen.c, to
support server side Fast Open cookie operations, including
/proc/sys/net/ipv4/tcp_fastopen_key to allow manual rekeying.
Signed-off-by: H.K. Jerry Chu <hkchu@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_fastopen.c')
-rw-r--r-- | net/ipv4/tcp_fastopen.c | 83 |
1 files changed, 82 insertions, 1 deletions
diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c index a7f729c409d..8f7ef0ad80e 100644 --- a/net/ipv4/tcp_fastopen.c +++ b/net/ipv4/tcp_fastopen.c @@ -1,10 +1,91 @@ +#include <linux/err.h> #include <linux/init.h> #include <linux/kernel.h> +#include <linux/list.h> +#include <linux/tcp.h> +#include <linux/rcupdate.h> +#include <linux/rculist.h> +#include <net/inetpeer.h> +#include <net/tcp.h> -int sysctl_tcp_fastopen; +int sysctl_tcp_fastopen __read_mostly; + +struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; + +static DEFINE_SPINLOCK(tcp_fastopen_ctx_lock); + +static void tcp_fastopen_ctx_free(struct rcu_head *head) +{ + struct tcp_fastopen_context *ctx = + container_of(head, struct tcp_fastopen_context, rcu); + crypto_free_cipher(ctx->tfm); + kfree(ctx); +} + +int tcp_fastopen_reset_cipher(void *key, unsigned int len) +{ + int err; + struct tcp_fastopen_context *ctx, *octx; + + ctx = kmalloc(sizeof(*ctx), GFP_KERNEL); + if (!ctx) + return -ENOMEM; + ctx->tfm = crypto_alloc_cipher("aes", 0, 0); + + if (IS_ERR(ctx->tfm)) { + err = PTR_ERR(ctx->tfm); +error: kfree(ctx); + pr_err("TCP: TFO aes cipher alloc error: %d\n", err); + return err; + } + err = crypto_cipher_setkey(ctx->tfm, key, len); + if (err) { + pr_err("TCP: TFO cipher key error: %d\n", err); + crypto_free_cipher(ctx->tfm); + goto error; + } + memcpy(ctx->key, key, len); + + spin_lock(&tcp_fastopen_ctx_lock); + + octx = rcu_dereference_protected(tcp_fastopen_ctx, + lockdep_is_held(&tcp_fastopen_ctx_lock)); + rcu_assign_pointer(tcp_fastopen_ctx, ctx); + spin_unlock(&tcp_fastopen_ctx_lock); + + if (octx) + call_rcu(&octx->rcu, tcp_fastopen_ctx_free); + return err; +} + +/* Computes the fastopen cookie for the peer. + * The peer address is a 128 bits long (pad with zeros for IPv4). + * + * The caller must check foc->len to determine if a valid cookie + * has been generated successfully. +*/ +void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc) +{ + __be32 peer_addr[4] = { addr, 0, 0, 0 }; + struct tcp_fastopen_context *ctx; + + rcu_read_lock(); + ctx = rcu_dereference(tcp_fastopen_ctx); + if (ctx) { + crypto_cipher_encrypt_one(ctx->tfm, + foc->val, + (__u8 *)peer_addr); + foc->len = TCP_FASTOPEN_COOKIE_SIZE; + } + rcu_read_unlock(); +} static int __init tcp_fastopen_init(void) { + __u8 key[TCP_FASTOPEN_KEY_LENGTH]; + + get_random_bytes(key, sizeof(key)); + tcp_fastopen_reset_cipher(key, sizeof(key)); return 0; } |