1046716368
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>
92 lines
2.2 KiB
C
92 lines
2.2 KiB
C
#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/tcp.h>
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#include <linux/rcupdate.h>
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#include <linux/rculist.h>
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#include <net/inetpeer.h>
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#include <net/tcp.h>
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int sysctl_tcp_fastopen __read_mostly;
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struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
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static DEFINE_SPINLOCK(tcp_fastopen_ctx_lock);
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static void tcp_fastopen_ctx_free(struct rcu_head *head)
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{
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struct tcp_fastopen_context *ctx =
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container_of(head, struct tcp_fastopen_context, rcu);
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crypto_free_cipher(ctx->tfm);
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kfree(ctx);
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}
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int tcp_fastopen_reset_cipher(void *key, unsigned int len)
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{
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int err;
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struct tcp_fastopen_context *ctx, *octx;
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ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
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if (!ctx)
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return -ENOMEM;
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ctx->tfm = crypto_alloc_cipher("aes", 0, 0);
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if (IS_ERR(ctx->tfm)) {
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err = PTR_ERR(ctx->tfm);
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error: kfree(ctx);
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pr_err("TCP: TFO aes cipher alloc error: %d\n", err);
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return err;
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}
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err = crypto_cipher_setkey(ctx->tfm, key, len);
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if (err) {
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pr_err("TCP: TFO cipher key error: %d\n", err);
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crypto_free_cipher(ctx->tfm);
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goto error;
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}
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memcpy(ctx->key, key, len);
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spin_lock(&tcp_fastopen_ctx_lock);
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octx = rcu_dereference_protected(tcp_fastopen_ctx,
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lockdep_is_held(&tcp_fastopen_ctx_lock));
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rcu_assign_pointer(tcp_fastopen_ctx, ctx);
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spin_unlock(&tcp_fastopen_ctx_lock);
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if (octx)
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call_rcu(&octx->rcu, tcp_fastopen_ctx_free);
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return err;
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}
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/* Computes the fastopen cookie for the peer.
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* The peer address is a 128 bits long (pad with zeros for IPv4).
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*
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* The caller must check foc->len to determine if a valid cookie
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* has been generated successfully.
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*/
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void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc)
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{
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__be32 peer_addr[4] = { addr, 0, 0, 0 };
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struct tcp_fastopen_context *ctx;
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rcu_read_lock();
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ctx = rcu_dereference(tcp_fastopen_ctx);
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if (ctx) {
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crypto_cipher_encrypt_one(ctx->tfm,
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foc->val,
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(__u8 *)peer_addr);
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foc->len = TCP_FASTOPEN_COOKIE_SIZE;
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}
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rcu_read_unlock();
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}
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static int __init tcp_fastopen_init(void)
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{
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__u8 key[TCP_FASTOPEN_KEY_LENGTH];
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get_random_bytes(key, sizeof(key));
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tcp_fastopen_reset_cipher(key, sizeof(key));
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return 0;
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}
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late_initcall(tcp_fastopen_init);
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