linux/tools/testing/selftests/bpf/test_sk_lookup_kern.c
Joe Stringer f71c6143c2 bpf: Support sk lookup in netns with id 0
David Ahern and Nicolas Dichtel report that the handling of the netns id
0 is incorrect for the BPF socket lookup helpers: rather than finding
the netns with id 0, it is resolving to the current netns. This renders
the netns_id 0 inaccessible.

To fix this, adjust the API for the netns to treat all negative s32
values as a lookup in the current netns (including u64 values which when
truncated to s32 become negative), while any values with a positive
value in the signed 32-bit integer space would result in a lookup for a
socket in the netns corresponding to that id. As before, if the netns
with that ID does not exist, no socket will be found. Any netns outside
of these ranges will fail to find a corresponding socket, as those
values are reserved for future usage.

Signed-off-by: Joe Stringer <joe@wand.net.nz>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Joey Pabalinas <joeypabalinas@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-11-30 17:17:38 -08:00

181 lines
4.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
// Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
#include <stddef.h>
#include <stdbool.h>
#include <string.h>
#include <linux/bpf.h>
#include <linux/if_ether.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/pkt_cls.h>
#include <linux/tcp.h>
#include <sys/socket.h>
#include "bpf_helpers.h"
#include "bpf_endian.h"
int _version SEC("version") = 1;
char _license[] SEC("license") = "GPL";
/* Fill 'tuple' with L3 info, and attempt to find L4. On fail, return NULL. */
static struct bpf_sock_tuple *get_tuple(void *data, __u64 nh_off,
void *data_end, __u16 eth_proto,
bool *ipv4)
{
struct bpf_sock_tuple *result;
__u8 proto = 0;
__u64 ihl_len;
if (eth_proto == bpf_htons(ETH_P_IP)) {
struct iphdr *iph = (struct iphdr *)(data + nh_off);
if (iph + 1 > data_end)
return NULL;
ihl_len = iph->ihl * 4;
proto = iph->protocol;
*ipv4 = true;
result = (struct bpf_sock_tuple *)&iph->saddr;
} else if (eth_proto == bpf_htons(ETH_P_IPV6)) {
struct ipv6hdr *ip6h = (struct ipv6hdr *)(data + nh_off);
if (ip6h + 1 > data_end)
return NULL;
ihl_len = sizeof(*ip6h);
proto = ip6h->nexthdr;
*ipv4 = true;
result = (struct bpf_sock_tuple *)&ip6h->saddr;
}
if (data + nh_off + ihl_len > data_end || proto != IPPROTO_TCP)
return NULL;
return result;
}
SEC("sk_lookup_success")
int bpf_sk_lookup_test0(struct __sk_buff *skb)
{
void *data_end = (void *)(long)skb->data_end;
void *data = (void *)(long)skb->data;
struct ethhdr *eth = (struct ethhdr *)(data);
struct bpf_sock_tuple *tuple;
struct bpf_sock *sk;
size_t tuple_len;
bool ipv4;
if (eth + 1 > data_end)
return TC_ACT_SHOT;
tuple = get_tuple(data, sizeof(*eth), data_end, eth->h_proto, &ipv4);
if (!tuple || tuple + sizeof *tuple > data_end)
return TC_ACT_SHOT;
tuple_len = ipv4 ? sizeof(tuple->ipv4) : sizeof(tuple->ipv6);
sk = bpf_sk_lookup_tcp(skb, tuple, tuple_len, BPF_F_CURRENT_NETNS, 0);
if (sk)
bpf_sk_release(sk);
return sk ? TC_ACT_OK : TC_ACT_UNSPEC;
}
SEC("sk_lookup_success_simple")
int bpf_sk_lookup_test1(struct __sk_buff *skb)
{
struct bpf_sock_tuple tuple = {};
struct bpf_sock *sk;
sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
if (sk)
bpf_sk_release(sk);
return 0;
}
SEC("fail_use_after_free")
int bpf_sk_lookup_uaf(struct __sk_buff *skb)
{
struct bpf_sock_tuple tuple = {};
struct bpf_sock *sk;
__u32 family = 0;
sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
if (sk) {
bpf_sk_release(sk);
family = sk->family;
}
return family;
}
SEC("fail_modify_sk_pointer")
int bpf_sk_lookup_modptr(struct __sk_buff *skb)
{
struct bpf_sock_tuple tuple = {};
struct bpf_sock *sk;
__u32 family;
sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
if (sk) {
sk += 1;
bpf_sk_release(sk);
}
return 0;
}
SEC("fail_modify_sk_or_null_pointer")
int bpf_sk_lookup_modptr_or_null(struct __sk_buff *skb)
{
struct bpf_sock_tuple tuple = {};
struct bpf_sock *sk;
__u32 family;
sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
sk += 1;
if (sk)
bpf_sk_release(sk);
return 0;
}
SEC("fail_no_release")
int bpf_sk_lookup_test2(struct __sk_buff *skb)
{
struct bpf_sock_tuple tuple = {};
bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
return 0;
}
SEC("fail_release_twice")
int bpf_sk_lookup_test3(struct __sk_buff *skb)
{
struct bpf_sock_tuple tuple = {};
struct bpf_sock *sk;
sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
bpf_sk_release(sk);
bpf_sk_release(sk);
return 0;
}
SEC("fail_release_unchecked")
int bpf_sk_lookup_test4(struct __sk_buff *skb)
{
struct bpf_sock_tuple tuple = {};
struct bpf_sock *sk;
sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
bpf_sk_release(sk);
return 0;
}
void lookup_no_release(struct __sk_buff *skb)
{
struct bpf_sock_tuple tuple = {};
bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
}
SEC("fail_no_release_subcall")
int bpf_sk_lookup_test5(struct __sk_buff *skb)
{
lookup_no_release(skb);
return 0;
}