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Merge branch 'Fix-collisions-in-socket-cookie-generation'

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Daniel Borkmann says:

====================
Fix collisions in socket cookie generation

This change makes the socket cookie generator as a global counter
instead of per netns in order to fix cookie collisions for BPF use
cases we ran into. See main patch #1 for more details.

Given the change is small/trivial and fixes an issue we're seeing
my preference would be net tree (though it cleanly applies to
net-next as well). Went for net tree instead of bpf tree here given
the main change is in net/core/sock_diag.c, but either way would be
fine with me.

v1 -> v2:
  - Fix up commit description in patch #1, thanks Eric!
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2019-08-09 13:14:46 -07:00
commit 703acf6259
4 changed files with 11 additions and 8 deletions
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1
include/net/net_namespace.h
View File

@ -61,7 +61,6 @@ struct net {
spinlock_t rules_mod_lock;
u32 hash_mix;
atomic64_t cookie_gen;
struct list_head list; /* list of network namespaces */
struct list_head exit_list; /* To linked to call pernet exit

4
include/uapi/linux/bpf.h
View File

@ -1466,8 +1466,8 @@ union bpf_attr {
* If no cookie has been set yet, generate a new cookie. Once
* generated, the socket cookie remains stable for the life of the
* socket. This helper can be useful for monitoring per socket
* networking traffic statistics as it provides a unique socket
* identifier per namespace.
* networking traffic statistics as it provides a global socket
* identifier that can be assumed unique.
* Return
* A 8-byte long non-decreasing number on success, or 0 if the
* socket field is missing inside *skb*.

3
net/core/sock_diag.c
View File

@ -19,6 +19,7 @@ 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);
static struct workqueue_struct *broadcast_wq;
static atomic64_t cookie_gen;
u64 sock_gen_cookie(struct sock *sk)
{
@ -27,7 +28,7 @@ u64 sock_gen_cookie(struct sock *sk)
if (res)
return res;
res = atomic64_inc_return(&sock_net(sk)->cookie_gen);
res = atomic64_inc_return(&cookie_gen);
atomic64_cmpxchg(&sk->sk_cookie, 0, res);
}
}

11
tools/include/uapi/linux/bpf.h
View File

@ -1466,8 +1466,8 @@ union bpf_attr {
* If no cookie has been set yet, generate a new cookie. Once
* generated, the socket cookie remains stable for the life of the
* socket. This helper can be useful for monitoring per socket
* networking traffic statistics as it provides a unique socket
* identifier per namespace.
* networking traffic statistics as it provides a global socket
* identifier that can be assumed unique.
* Return
* A 8-byte long non-decreasing number on success, or 0 if the
* socket field is missing inside *skb*.
@ -1571,8 +1571,11 @@ union bpf_attr {
* but this is only implemented for native XDP (with driver
* support) as of this writing).
*
* All values for *flags* are reserved for future usage, and must
* be left at zero.
* The lower two bits of *flags* are used as the return code if
* the map lookup fails. This is so that the return value can be
* one of the XDP program return codes up to XDP_TX, as chosen by
* the caller. Any higher bits in the *flags* argument must be
* unset.
*
* When used to redirect packets to net devices, this helper
* provides a high performance increase over **bpf_redirect**\ ().