[PATCH ipsec-next v3 7/9] bpf: selftests: test_tunnel: Use vmlinux.h declarations

Daniel Xu
2023-12-01T20:24:19Z

vmlinux.h declarations are more ergnomic, especially when working with
kfuncs. The uapi headers are often incomplete for kfunc definitions.

This commit also switches bitfield accesses to use CO-RE helpers.
Switching to vmlinux.h definitions makes the verifier very
unhappy with raw bitfield accesses. The error is:

; md.u.md2.dir = direction;
33: (69) r1 = *(u16 *)(r2 +11)
misaligned stack access off (0x0; 0x0)+-64+11 size 2

Fix by using CO-RE-aware bitfield reads and writes.

Co-developed-by: Antony Antony <antony.antony@secunet.com>
Signed-off-by: Antony Antony <antony.antony@secunet.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
---
.../selftests/bpf/progs/bpf_tracing_net.h | 1 +
.../selftests/bpf/progs/test_tunnel_kern.c | 76 +++++--------------
2 files changed, 22 insertions(+), 55 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/bpf_tracing_net.h b/tools/testing/selftests/bpf/progs/bpf_tracing_net.h
index 0b793a102791..1bdc680b0e0e 100644
--- a/tools/testing/selftests/bpf/progs/bpf_tracing_net.h
+++ b/tools/testing/selftests/bpf/progs/bpf_tracing_net.h
@@ -26,6 +26,7 @@
#define IPV6_AUTOFLOWLABEL 70

#define TC_ACT_UNSPEC (-1)
+#define TC_ACT_OK 0
#define TC_ACT_SHOT 2

#define SOL_TCP 6
diff --git a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c b/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
index f66af753bbbb..b320fb7bb080 100644
--- a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
+++ b/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
@@ -6,62 +6,26 @@
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*/
-#include <stddef.h>
-#include <string.h>
-#include <arpa/inet.h>
-#include <linux/bpf.h>
-#include <linux/if_ether.h>
-#include <linux/if_packet.h>
-#include <linux/if_tunnel.h>
-#include <linux/ip.h>
-#include <linux/ipv6.h>
-#include <linux/icmp.h>
-#include <linux/types.h>
-#include <linux/socket.h>
-#include <linux/pkt_cls.h>
-#include <linux/erspan.h>
-#include <linux/udp.h>
+#include "vmlinux.h"
+#include <bpf/bpf_core_read.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>
+#include "bpf_kfuncs.h"
+#include "bpf_tracing_net.h"

#define log_err(__ret) bpf_printk("ERROR line:%d ret:%d\n", __LINE__, __ret)

-#define VXLAN_UDP_PORT 4789
+#define VXLAN_UDP_PORT 4789
+#define ETH_P_IP 0x0800
+#define PACKET_HOST 0
+#define TUNNEL_CSUM bpf_htons(0x01)
+#define TUNNEL_KEY bpf_htons(0x04)

/* Only IPv4 address assigned to veth1.
* 172.16.1.200
*/
#define ASSIGNED_ADDR_VETH1 0xac1001c8

-struct geneve_opt {
- __be16 opt_class;
- __u8 type;
- __u8 length:5;
- __u8 r3:1;
- __u8 r2:1;
- __u8 r1:1;
- __u8 opt_data[8]; /* hard-coded to 8 byte */
-};
-
-struct vxlanhdr {
- __be32 vx_flags;
- __be32 vx_vni;
-} __attribute__((packed));
-
-struct vxlan_metadata {
- __u32 gbp;
-};
-
-struct bpf_fou_encap {
- __be16 sport;
- __be16 dport;
-};
-
-enum bpf_fou_encap_type {
- FOU_BPF_ENCAP_FOU,
- FOU_BPF_ENCAP_GUE,
-};
-
int bpf_skb_set_fou_encap(struct __sk_buff *skb_ctx,
struct bpf_fou_encap *encap, int type) __ksym;
int bpf_skb_get_fou_encap(struct __sk_buff *skb_ctx,
@@ -205,9 +169,9 @@ int erspan_set_tunnel(struct __sk_buff *skb)
__u8 hwid = 7;

md.version = 2;
- md.u.md2.dir = direction;
- md.u.md2.hwid = hwid & 0xf;
- md.u.md2.hwid_upper = (hwid >> 4) & 0x3;
+ BPF_CORE_WRITE_BITFIELD(&md.u.md2, dir, direction);
+ BPF_CORE_WRITE_BITFIELD(&md.u.md2, hwid, (hwid & 0xf));
+ BPF_CORE_WRITE_BITFIELD(&md.u.md2, hwid_upper, (hwid >> 4) & 0x3);
#endif

ret = bpf_skb_set_tunnel_opt(skb, &md, sizeof(md));
@@ -246,8 +210,9 @@ int erspan_get_tunnel(struct __sk_buff *skb)
bpf_printk("\tindex %x\n", index);
#else
bpf_printk("\tdirection %d hwid %x timestamp %u\n",
- md.u.md2.dir,
- (md.u.md2.hwid_upper << 4) + md.u.md2.hwid,
+ BPF_CORE_READ_BITFIELD(&md.u.md2, dir),
+ (BPF_CORE_READ_BITFIELD(&md.u.md2, hwid_upper) << 4) +
+ BPF_CORE_READ_BITFIELD(&md.u.md2, hwid),
bpf_ntohl(md.u.md2.timestamp));
#endif

@@ -284,9 +249,9 @@ int ip4ip6erspan_set_tunnel(struct __sk_buff *skb)
__u8 hwid = 17;

md.version = 2;
- md.u.md2.dir = direction;
- md.u.md2.hwid = hwid & 0xf;
- md.u.md2.hwid_upper = (hwid >> 4) & 0x3;
+ BPF_CORE_WRITE_BITFIELD(&md.u.md2, dir, direction);
+ BPF_CORE_WRITE_BITFIELD(&md.u.md2, hwid, (hwid & 0xf));
+ BPF_CORE_WRITE_BITFIELD(&md.u.md2, hwid_upper, (hwid >> 4) & 0x3);
#endif

ret = bpf_skb_set_tunnel_opt(skb, &md, sizeof(md));
@@ -326,8 +291,9 @@ int ip4ip6erspan_get_tunnel(struct __sk_buff *skb)
bpf_printk("\tindex %x\n", index);
#else
bpf_printk("\tdirection %d hwid %x timestamp %u\n",
- md.u.md2.dir,
- (md.u.md2.hwid_upper << 4) + md.u.md2.hwid,
+ BPF_CORE_READ_BITFIELD(&md.u.md2, dir),
+ (BPF_CORE_READ_BITFIELD(&md.u.md2, hwid_upper) << 4) +
+ BPF_CORE_READ_BITFIELD(&md.u.md2, hwid),
bpf_ntohl(md.u.md2.timestamp));
#endif

--
2.42.1