Commit 037b0b86 authored Aug 16, 2018 by Daniel Borkmann Committed by Alexei Starovoitov Aug 16, 2018

tcp, ulp: add alias for all ulp modules



Lets not turn the TCP ULP lookup into an arbitrary module loader as
we only intend to load ULP modules through this mechanism, not other
unrelated kernel modules:

  [root@bar]# cat foo.c
  #include <sys/types.h>
  #include <sys/socket.h>
  #include <linux/tcp.h>
  #include <linux/in.h>

  int main(void)
  {
      int sock = socket(PF_INET, SOCK_STREAM, 0);
      setsockopt(sock, IPPROTO_TCP, TCP_ULP, "sctp", sizeof("sctp"));
      return 0;
  }

  [root@bar]# gcc foo.c -O2 -Wall
  [root@bar]# lsmod | grep sctp
  [root@bar]# ./a.out
  [root@bar]# lsmod | grep sctp
  sctp                 1077248  4
  libcrc32c              16384  3 nf_conntrack,nf_nat,sctp
  [root@bar]#

Fix it by adding module alias to TCP ULP modules, so probing module
via request_module() will be limited to tcp-ulp-[name]. The existing
modules like kTLS will load fine given tcp-ulp-tls alias, but others
will fail to load:

  [root@bar]# lsmod | grep sctp
  [root@bar]# ./a.out
  [root@bar]# lsmod | grep sctp
  [root@bar]#

Sockmap is not affected from this since it's either built-in or not.

Fixes: 734942cc ("tcp: ULP infrastructure")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

parent 965931e3

include/net/tcp.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -2065,6 +2065,10 @@ int tcp_set_ulp_id(struct sock *sk, const int ulp);
		void tcp_get_available_ulp(char *buf, size_t len);
		void tcp_cleanup_ulp(struct sock *sk);

		#define MODULE_ALIAS_TCP_ULP(name) \
		__MODULE_INFO(alias, alias_userspace, name); \
		__MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name)

		/* Call BPF_SOCK_OPS program that returns an int. If the return value
		* is < 0, then the BPF op failed (for example if the loaded BPF
		* program does not support the chosen operation or there is no BPF

net/ipv4/tcp_ulp.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -51,7 +51,7 @@ static const struct tcp_ulp_ops __tcp_ulp_find_autoload(const char name)
		#ifdef CONFIG_MODULES
		if (!ulp && capable(CAP_NET_ADMIN)) {
		rcu_read_unlock();
		request_module("%s", name);
		request_module("tcp-ulp-%s", name);
		rcu_read_lock();
		ulp = tcp_ulp_find(name);
		}

net/tls/tls_main.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -45,6 +45,7 @@
		MODULE_AUTHOR("Mellanox Technologies");
		MODULE_DESCRIPTION("Transport Layer Security Support");
		MODULE_LICENSE("Dual BSD/GPL");
		MODULE_ALIAS_TCP_ULP("tls");

		enum {
		TLSV4,