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authorWilliam Allen Simpson <william.allen.simpson@gmail.com>2009-12-02 13:17:05 -0500
committerDavid S. Miller <davem@davemloft.net>2009-12-03 01:07:25 -0500
commit435cf559f02ea3a3159eb316f97dc88bdebe9432 (patch)
tree0b2a7e9110c46b193176b0a59fe5689eae7c18f3 /net/ipv4/tcp_ipv4.c
parent519855c508b9a17878c0977a3cdefc09b59b30df (diff)
TCPCT part 1d: define TCP cookie option, extend existing struct's
Data structures are carefully composed to require minimal additions. For example, the struct tcp_options_received cookie_plus variable fits between existing 16-bit and 8-bit variables, requiring no additional space (taking alignment into consideration). There are no additions to tcp_request_sock, and only 1 pointer in tcp_sock. This is a significantly revised implementation of an earlier (year-old) patch that no longer applies cleanly, with permission of the original author (Adam Langley): http://thread.gmane.org/gmane.linux.network/102586 The principle difference is using a TCP option to carry the cookie nonce, instead of a user configured offset in the data. This is more flexible and less subject to user configuration error. Such a cookie option has been suggested for many years, and is also useful without SYN data, allowing several related concepts to use the same extension option. "Re: SYN floods (was: does history repeat itself?)", September 9, 1996. http://www.merit.net/mail.archives/nanog/1996-09/msg00235.html "Re: what a new TCP header might look like", May 12, 1998. ftp://ftp.isi.edu/end2end/end2end-interest-1998.mail These functions will also be used in subsequent patches that implement additional features. Requires: TCPCT part 1a: add request_values parameter for sending SYNACK TCPCT part 1b: generate Responder Cookie secret TCPCT part 1c: sysctl_tcp_cookie_size, socket option TCP_COOKIE_TRANSACTIONS Signed-off-by: William.Allen.Simpson@gmail.com Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_ipv4.c')
-rw-r--r--net/ipv4/tcp_ipv4.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 649a36d99c73..a2bcac9b388e 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1833,6 +1833,19 @@ static int tcp_v4_init_sock(struct sock *sk)
1833 tp->af_specific = &tcp_sock_ipv4_specific; 1833 tp->af_specific = &tcp_sock_ipv4_specific;
1834#endif 1834#endif
1835 1835
1836 /* TCP Cookie Transactions */
1837 if (sysctl_tcp_cookie_size > 0) {
1838 /* Default, cookies without s_data_payload. */
1839 tp->cookie_values =
1840 kzalloc(sizeof(*tp->cookie_values),
1841 sk->sk_allocation);
1842 if (tp->cookie_values != NULL)
1843 kref_init(&tp->cookie_values->kref);
1844 }
1845 /* Presumed zeroed, in order of appearance:
1846 * cookie_in_always, cookie_out_never,
1847 * s_data_constant, s_data_in, s_data_out
1848 */
1836 sk->sk_sndbuf = sysctl_tcp_wmem[1]; 1849 sk->sk_sndbuf = sysctl_tcp_wmem[1];
1837 sk->sk_rcvbuf = sysctl_tcp_rmem[1]; 1850 sk->sk_rcvbuf = sysctl_tcp_rmem[1];
1838 1851
@@ -1886,6 +1899,13 @@ void tcp_v4_destroy_sock(struct sock *sk)
1886 sk->sk_sndmsg_page = NULL; 1899 sk->sk_sndmsg_page = NULL;
1887 } 1900 }
1888 1901
1902 /* TCP Cookie Transactions */
1903 if (tp->cookie_values != NULL) {
1904 kref_put(&tp->cookie_values->kref,
1905 tcp_cookie_values_release);
1906 tp->cookie_values = NULL;
1907 }
1908
1889 percpu_counter_dec(&tcp_sockets_allocated); 1909 percpu_counter_dec(&tcp_sockets_allocated);
1890} 1910}
1891 1911