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Merge branch 'bpf: Fix src IP addr related limitation in bpf_*_fib_lookup()'

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Martynas Pumputis says:

====================
The patchset fixes the limitation of bpf_*_fib_lookup() helper, which
prevents it from being used in BPF dataplanes with network interfaces
which have more than one IP addr. See the first patch for more details.
Thanks!

* v2->v3: Address Martin KaFai Lau's feedback
* v1->v2: Use IPv6 stubs to fix compilation when CONFIG_IPV6=m.
====================

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This commit is contained in:
Martin KaFai Lau 2023-10-09 15:35:00 -07:00
commit 1ef09e1281
6 changed files with 120 additions and 7 deletions
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5
include/net/ipv6_stubs.h
View File

@ -85,6 +85,11 @@ struct ipv6_bpf_stub {
sockptr_t optval, unsigned int optlen);
int (*ipv6_getsockopt)(struct sock *sk, int level, int optname,
sockptr_t optval, sockptr_t optlen);
int (*ipv6_dev_get_saddr)(struct net *net,
const struct net_device *dst_dev,
const struct in6_addr *daddr,
unsigned int prefs,
struct in6_addr *saddr);
};
extern const struct ipv6_bpf_stub *ipv6_bpf_stub __read_mostly;

10
include/uapi/linux/bpf.h
View File

@ -3264,6 +3264,11 @@ union bpf_attr {
* and *params*->smac will not be set as output. A common
* use case is to call **bpf_redirect_neigh**\ () after
* doing **bpf_fib_lookup**\ ().
* **BPF_FIB_LOOKUP_SRC**
* Derive and set source IP addr in *params*->ipv{4,6}_src
* for the nexthop. If the src addr cannot be derived,
* **BPF_FIB_LKUP_RET_NO_SRC_ADDR** is returned. In this
* case, *params*->dmac and *params*->smac are not set either.
*
* *ctx* is either **struct xdp_md** for XDP programs or
* **struct sk_buff** tc cls_act programs.
@ -6964,6 +6969,7 @@ enum {
BPF_FIB_LOOKUP_OUTPUT = (1U << 1),
BPF_FIB_LOOKUP_SKIP_NEIGH = (1U << 2),
BPF_FIB_LOOKUP_TBID = (1U << 3),
BPF_FIB_LOOKUP_SRC = (1U << 4),
};
enum {
@ -6976,6 +6982,7 @@ enum {
BPF_FIB_LKUP_RET_UNSUPP_LWT, /* fwd requires encapsulation */
BPF_FIB_LKUP_RET_NO_NEIGH, /* no neighbor entry for nh */
BPF_FIB_LKUP_RET_FRAG_NEEDED, /* fragmentation required to fwd */
BPF_FIB_LKUP_RET_NO_SRC_ADDR, /* failed to derive IP src addr */
};
struct bpf_fib_lookup {
@ -7010,6 +7017,9 @@ struct bpf_fib_lookup {
__u32 rt_metric;
};
/* input: source address to consider for lookup
* output: source address result from lookup
*/
union {
__be32 ipv4_src;
__u32 ipv6_src[4]; /* in6_addr; network order */

18
net/core/filter.c
View File

@ -5850,6 +5850,9 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
params->rt_metric = res.fi->fib_priority;
params->ifindex = dev->ifindex;
if (flags & BPF_FIB_LOOKUP_SRC)
params->ipv4_src = fib_result_prefsrc(net, &res);
/* xdp and cls_bpf programs are run in RCU-bh so
* rcu_read_lock_bh is not needed here
*/
@ -5992,6 +5995,18 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
params->rt_metric = res.f6i->fib6_metric;
params->ifindex = dev->ifindex;
if (flags & BPF_FIB_LOOKUP_SRC) {
if (res.f6i->fib6_prefsrc.plen) {
*src = res.f6i->fib6_prefsrc.addr;
} else {
err = ipv6_bpf_stub->ipv6_dev_get_saddr(net, dev,
&fl6.daddr, 0,
src);
if (err)
return BPF_FIB_LKUP_RET_NO_SRC_ADDR;
}
}
if (flags & BPF_FIB_LOOKUP_SKIP_NEIGH)
goto set_fwd_params;
@ -6010,7 +6025,8 @@ set_fwd_params:
#endif
#define BPF_FIB_LOOKUP_MASK (BPF_FIB_LOOKUP_DIRECT | BPF_FIB_LOOKUP_OUTPUT | \
BPF_FIB_LOOKUP_SKIP_NEIGH | BPF_FIB_LOOKUP_TBID)
BPF_FIB_LOOKUP_SKIP_NEIGH | BPF_FIB_LOOKUP_TBID | \
BPF_FIB_LOOKUP_SRC)
BPF_CALL_4(bpf_xdp_fib_lookup, struct xdp_buff *, ctx,
struct bpf_fib_lookup *, params, int, plen, u32, flags)

1
net/ipv6/af_inet6.c
View File

@ -1061,6 +1061,7 @@ static const struct ipv6_bpf_stub ipv6_bpf_stub_impl = {
.udp6_lib_lookup = __udp6_lib_lookup,
.ipv6_setsockopt = do_ipv6_setsockopt,
.ipv6_getsockopt = do_ipv6_getsockopt,
.ipv6_dev_get_saddr = ipv6_dev_get_saddr,
};
static int __init inet6_init(void)

10
tools/include/uapi/linux/bpf.h
View File

@ -3264,6 +3264,11 @@ union bpf_attr {
* and *params*->smac will not be set as output. A common
* use case is to call **bpf_redirect_neigh**\ () after
* doing **bpf_fib_lookup**\ ().
* **BPF_FIB_LOOKUP_SRC**
* Derive and set source IP addr in *params*->ipv{4,6}_src
* for the nexthop. If the src addr cannot be derived,
* **BPF_FIB_LKUP_RET_NO_SRC_ADDR** is returned. In this
* case, *params*->dmac and *params*->smac are not set either.
*
* *ctx* is either **struct xdp_md** for XDP programs or
* **struct sk_buff** tc cls_act programs.
@ -6964,6 +6969,7 @@ enum {
BPF_FIB_LOOKUP_OUTPUT = (1U << 1),
BPF_FIB_LOOKUP_SKIP_NEIGH = (1U << 2),
BPF_FIB_LOOKUP_TBID = (1U << 3),
BPF_FIB_LOOKUP_SRC = (1U << 4),
};
enum {
@ -6976,6 +6982,7 @@ enum {
BPF_FIB_LKUP_RET_UNSUPP_LWT, /* fwd requires encapsulation */
BPF_FIB_LKUP_RET_NO_NEIGH, /* no neighbor entry for nh */
BPF_FIB_LKUP_RET_FRAG_NEEDED, /* fragmentation required to fwd */
BPF_FIB_LKUP_RET_NO_SRC_ADDR, /* failed to derive IP src addr */
};
struct bpf_fib_lookup {
@ -7010,6 +7017,9 @@ struct bpf_fib_lookup {
__u32 rt_metric;
};
/* input: source address to consider for lookup
* output: source address result from lookup
*/
union {
__be32 ipv4_src;
__u32 ipv6_src[4]; /* in6_addr; network order */

83
tools/testing/selftests/bpf/prog_tests/fib_lookup.c
View File

@ -11,9 +11,13 @@
#define NS_TEST "fib_lookup_ns"
#define IPV6_IFACE_ADDR "face::face"
#define IPV6_IFACE_ADDR_SEC "cafe::cafe"
#define IPV6_ADDR_DST "face::3"
#define IPV6_NUD_FAILED_ADDR "face::1"
#define IPV6_NUD_STALE_ADDR "face::2"
#define IPV4_IFACE_ADDR "10.0.0.254"
#define IPV4_IFACE_ADDR_SEC "10.1.0.254"
#define IPV4_ADDR_DST "10.2.0.254"
#define IPV4_NUD_FAILED_ADDR "10.0.0.1"
#define IPV4_NUD_STALE_ADDR "10.0.0.2"
#define IPV4_TBID_ADDR "172.0.0.254"
@ -31,6 +35,7 @@ struct fib_lookup_test {
const char *desc;
const char *daddr;
int expected_ret;
const char *expected_src;
int lookup_flags;
__u32 tbid;
__u8 dmac[6];
@ -69,6 +74,22 @@ static const struct fib_lookup_test tests[] = {
.daddr = IPV6_TBID_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
.lookup_flags = BPF_FIB_LOOKUP_DIRECT | BPF_FIB_LOOKUP_TBID, .tbid = 100,
.dmac = DMAC_INIT2, },
{ .desc = "IPv4 set src addr from netdev",
.daddr = IPV4_NUD_FAILED_ADDR, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
.expected_src = IPV4_IFACE_ADDR,
.lookup_flags = BPF_FIB_LOOKUP_SRC | BPF_FIB_LOOKUP_SKIP_NEIGH, },
{ .desc = "IPv6 set src addr from netdev",
.daddr = IPV6_NUD_FAILED_ADDR, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
.expected_src = IPV6_IFACE_ADDR,
.lookup_flags = BPF_FIB_LOOKUP_SRC | BPF_FIB_LOOKUP_SKIP_NEIGH, },
{ .desc = "IPv4 set prefsrc addr from route",
.daddr = IPV4_ADDR_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
.expected_src = IPV4_IFACE_ADDR_SEC,
.lookup_flags = BPF_FIB_LOOKUP_SRC | BPF_FIB_LOOKUP_SKIP_NEIGH, },
{ .desc = "IPv6 set prefsrc addr route",
.daddr = IPV6_ADDR_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
.expected_src = IPV6_IFACE_ADDR_SEC,
.lookup_flags = BPF_FIB_LOOKUP_SRC | BPF_FIB_LOOKUP_SKIP_NEIGH, },
};
static int ifindex;
@ -97,6 +118,13 @@ static int setup_netns(void)
SYS(fail, "ip neigh add %s dev veth1 nud failed", IPV4_NUD_FAILED_ADDR);
SYS(fail, "ip neigh add %s dev veth1 lladdr %s nud stale", IPV4_NUD_STALE_ADDR, DMAC);
/* Setup for prefsrc IP addr selection */
SYS(fail, "ip addr add %s/24 dev veth1", IPV4_IFACE_ADDR_SEC);
SYS(fail, "ip route add %s/32 dev veth1 src %s", IPV4_ADDR_DST, IPV4_IFACE_ADDR_SEC);
SYS(fail, "ip addr add %s/64 dev veth1 nodad", IPV6_IFACE_ADDR_SEC);
SYS(fail, "ip route add %s/128 dev veth1 src %s", IPV6_ADDR_DST, IPV6_IFACE_ADDR_SEC);
/* Setup for tbid lookup tests */
SYS(fail, "ip addr add %s/24 dev veth2", IPV4_TBID_ADDR);
SYS(fail, "ip route del %s/24 dev veth2", IPV4_TBID_NET);
@ -133,9 +161,12 @@ static int set_lookup_params(struct bpf_fib_lookup *params, const struct fib_loo
if (inet_pton(AF_INET6, test->daddr, params->ipv6_dst) == 1) {
params->family = AF_INET6;
ret = inet_pton(AF_INET6, IPV6_IFACE_ADDR, params->ipv6_src);
if (!ASSERT_EQ(ret, 1, "inet_pton(IPV6_IFACE_ADDR)"))
return -1;
if (!(test->lookup_flags & BPF_FIB_LOOKUP_SRC)) {
ret = inet_pton(AF_INET6, IPV6_IFACE_ADDR, params->ipv6_src);
if (!ASSERT_EQ(ret, 1, "inet_pton(IPV6_IFACE_ADDR)"))
return -1;
}
return 0;
}
@ -143,9 +174,12 @@ static int set_lookup_params(struct bpf_fib_lookup *params, const struct fib_loo
if (!ASSERT_EQ(ret, 1, "convert IP[46] address"))
return -1;
params->family = AF_INET;
ret = inet_pton(AF_INET, IPV4_IFACE_ADDR, &params->ipv4_src);
if (!ASSERT_EQ(ret, 1, "inet_pton(IPV4_IFACE_ADDR)"))
return -1;
if (!(test->lookup_flags & BPF_FIB_LOOKUP_SRC)) {
ret = inet_pton(AF_INET, IPV4_IFACE_ADDR, &params->ipv4_src);
if (!ASSERT_EQ(ret, 1, "inet_pton(IPV4_IFACE_ADDR)"))
return -1;
}
return 0;
}
@ -156,6 +190,40 @@ static void mac_str(char *b, const __u8 *mac)
mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
}
static void assert_src_ip(struct bpf_fib_lookup *fib_params, const char *expected_src)
{
int ret;
__u32 src6[4];
__be32 src4;
switch (fib_params->family) {
case AF_INET6:
ret = inet_pton(AF_INET6, expected_src, src6);
ASSERT_EQ(ret, 1, "inet_pton(expected_src)");
ret = memcmp(src6, fib_params->ipv6_src, sizeof(fib_params->ipv6_src));
if (!ASSERT_EQ(ret, 0, "fib_lookup ipv6 src")) {
char str_src6[64];
inet_ntop(AF_INET6, fib_params->ipv6_src, str_src6,
sizeof(str_src6));
printf("ipv6 expected %s actual %s ", expected_src,
str_src6);
}
break;
case AF_INET:
ret = inet_pton(AF_INET, expected_src, &src4);
ASSERT_EQ(ret, 1, "inet_pton(expected_src)");
ASSERT_EQ(fib_params->ipv4_src, src4, "fib_lookup ipv4 src");
break;
default:
PRINT_FAIL("invalid addr family: %d", fib_params->family);
}
}
void test_fib_lookup(void)
{
struct bpf_fib_lookup *fib_params;
@ -207,6 +275,9 @@ void test_fib_lookup(void)
ASSERT_EQ(skel->bss->fib_lookup_ret, tests[i].expected_ret,
"fib_lookup_ret");
if (tests[i].expected_src)
assert_src_ip(fib_params, tests[i].expected_src);
ret = memcmp(tests[i].dmac, fib_params->dmac, sizeof(tests[i].dmac));
if (!ASSERT_EQ(ret, 0, "dmac not match")) {
char expected[18], actual[18];