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net: add real socket cookies

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A long standing problem in netlink socket dumps is the use
of kernel socket addresses as cookies.

1) It is a security concern.

2) Sockets can be reused quite quickly, so there is
   no guarantee a cookie is used once and identify
   a flow.

3) request sock, establish sock, and timewait socks
   for a given flow have different cookies.

Part of our effort to bring better TCP statistics requires
to switch to a different allocator.

In this patch, I chose to use a per network namespace 64bit generator,
and to use it only in the case a socket needs to be dumped to netlink.
(This might be refined later if needed)

Note that I tried to carry cookies from request sock, to establish sock,
then timewait sockets.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Eric Salo <salo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2015-03-11 18:53:14 -07:00
committed by David S. Miller
parent 654eff4516
commit 33cf7c90fe
13 changed files with 55 additions and 17 deletions
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1
net/core/sock.c
View File

@@ -1538,6 +1538,7 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
newsk->sk_err = 0;
newsk->sk_priority = 0;
newsk->sk_incoming_cpu = raw_smp_processor_id();
atomic64_set(&newsk->sk_cookie, 0);
/*
* Before updating sk_refcnt, we must commit prior changes to memory
* (Documentation/RCU/rculist_nulls.txt for details)

37
net/core/sock_diag.c
View File

@@ -13,22 +13,39 @@ static const struct sock_diag_handler *sock_diag_handlers[AF_MAX];
static int (*inet_rcv_compat)(struct sk_buff *skb, struct nlmsghdr *nlh);
static DEFINE_MUTEX(sock_diag_table_mutex);
int sock_diag_check_cookie(void *sk, const __u32 *cookie)
static u64 sock_gen_cookie(struct sock *sk)
{
if ((cookie[0] != INET_DIAG_NOCOOKIE ||
cookie[1] != INET_DIAG_NOCOOKIE) &&
((u32)(unsigned long)sk != cookie[0] ||
(u32)((((unsigned long)sk) >> 31) >> 1) != cookie[1]))
return -ESTALE;
else
while (1) {
u64 res = atomic64_read(&sk->sk_cookie);
if (res)
return res;
res = atomic64_inc_return(&sock_net(sk)->cookie_gen);
atomic64_cmpxchg(&sk->sk_cookie, 0, res);
}
}
int sock_diag_check_cookie(struct sock *sk, const __u32 *cookie)
{
u64 res;
if (cookie[0] == INET_DIAG_NOCOOKIE && cookie[1] == INET_DIAG_NOCOOKIE)
return 0;
res = sock_gen_cookie(sk);
if ((u32)res != cookie[0] || (u32)(res >> 32) != cookie[1])
return -ESTALE;
return 0;
}
EXPORT_SYMBOL_GPL(sock_diag_check_cookie);
void sock_diag_save_cookie(void *sk, __u32 *cookie)
void sock_diag_save_cookie(struct sock *sk, __u32 *cookie)
{
cookie[0] = (u32)(unsigned long)sk;
cookie[1] = (u32)(((unsigned long)sk >> 31) >> 1);
u64 res = sock_gen_cookie(sk);
cookie[0] = (u32)res;
cookie[1] = (u32)(res >> 32);
}
EXPORT_SYMBOL_GPL(sock_diag_save_cookie);