selftests/bpf: add a test case to check verifier pointer arithmetic
With clang/llvm 4.0+, the test case is able to generate
the following pattern:
....
440: (b7) r1 = 15
441: (05) goto pc+73
515: (79) r6 = *(u64 *)(r10 -152)
516: (bf) r7 = r10
517: (07) r7 += -112
518: (bf) r2 = r7
519: (0f) r2 += r1
520: (71) r1 = *(u8 *)(r8 +0)
521: (73) *(u8 *)(r2 +45) = r1
....
commit 332270fdc8 ("bpf: enhance verifier to understand stack
pointer arithmetic") improved verifier to handle such a pattern.
This patch adds a C test case to actually generate such a pattern.
A dummy tracepoint interface is used to load the program
into the kernel.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yonghong Song
David S. Miller
parent
4d463c4dbc
commit
6ead18fb18
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@ -13,7 +13,7 @@ LDLIBS += -lcap -lelf
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TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs
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TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o
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TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o
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TEST_PROGS := test_kmod.sh
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@ -268,6 +268,21 @@ out:
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bpf_object__close(obj);
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}
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static void test_tcp_estats(void)
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{
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const char *file = "./test_tcp_estats.o";
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int err, prog_fd;
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struct bpf_object *obj;
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__u32 duration = 0;
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err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
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CHECK(err, "", "err %d errno %d\n", err, errno);
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if (err)
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return;
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bpf_object__close(obj);
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}
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int main(void)
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{
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struct rlimit rinf = { RLIM_INFINITY, RLIM_INFINITY };
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@ -277,6 +292,7 @@ int main(void)
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test_pkt_access();
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test_xdp();
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test_l4lb();
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test_tcp_estats();
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printf("Summary: %d PASSED, %d FAILED\n", pass_cnt, error_cnt);
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return 0;
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@ -0,0 +1,258 @@
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/* Copyright (c) 2017 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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/* This program shows clang/llvm is able to generate code pattern
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* like:
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* _tcp_send_active_reset:
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* 0: bf 16 00 00 00 00 00 00 r6 = r1
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* ......
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* 335: b7 01 00 00 0f 00 00 00 r1 = 15
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* 336: 05 00 48 00 00 00 00 00 goto 72
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*
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* LBB0_3:
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* 337: b7 01 00 00 01 00 00 00 r1 = 1
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* 338: 63 1a d0 ff 00 00 00 00 *(u32 *)(r10 - 48) = r1
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* 408: b7 01 00 00 03 00 00 00 r1 = 3
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*
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* LBB0_4:
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* 409: 71 a2 fe ff 00 00 00 00 r2 = *(u8 *)(r10 - 2)
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* 410: bf a7 00 00 00 00 00 00 r7 = r10
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* 411: 07 07 00 00 b8 ff ff ff r7 += -72
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* 412: bf 73 00 00 00 00 00 00 r3 = r7
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* 413: 0f 13 00 00 00 00 00 00 r3 += r1
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* 414: 73 23 2d 00 00 00 00 00 *(u8 *)(r3 + 45) = r2
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*
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* From the above code snippet, the code generated by the compiler
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* is reasonable. The "r1" is assigned to different values in basic
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* blocks "_tcp_send_active_reset" and "LBB0_3", and used in "LBB0_4".
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* The verifier should be able to handle such code patterns.
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*/
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#include <string.h>
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#include <linux/bpf.h>
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#include <linux/ipv6.h>
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#include <linux/version.h>
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#include <sys/socket.h>
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#include "bpf_helpers.h"
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#define _(P) ({typeof(P) val = 0; bpf_probe_read(&val, sizeof(val), &P); val;})
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#define TCP_ESTATS_MAGIC 0xBAADBEEF
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/* This test case needs "sock" and "pt_regs" data structure.
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* Recursively, "sock" needs "sock_common" and "inet_sock".
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* However, this is a unit test case only for
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* verifier purpose without bpf program execution.
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* We can safely mock much simpler data structures, basically
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* only taking the necessary fields from kernel headers.
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*/
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typedef __u32 __bitwise __portpair;
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typedef __u64 __bitwise __addrpair;
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struct sock_common {
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unsigned short skc_family;
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union {
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__addrpair skc_addrpair;
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struct {
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__be32 skc_daddr;
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__be32 skc_rcv_saddr;
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};
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};
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union {
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__portpair skc_portpair;
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struct {
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__be16 skc_dport;
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__u16 skc_num;
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};
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};
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struct in6_addr skc_v6_daddr;
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struct in6_addr skc_v6_rcv_saddr;
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};
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struct sock {
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struct sock_common __sk_common;
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#define sk_family __sk_common.skc_family
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#define sk_v6_daddr __sk_common.skc_v6_daddr
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#define sk_v6_rcv_saddr __sk_common.skc_v6_rcv_saddr
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};
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struct inet_sock {
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struct sock sk;
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#define inet_daddr sk.__sk_common.skc_daddr
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#define inet_dport sk.__sk_common.skc_dport
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__be32 inet_saddr;
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__be16 inet_sport;
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};
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struct pt_regs {
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long di;
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};
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static inline struct inet_sock *inet_sk(const struct sock *sk)
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{
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return (struct inet_sock *)sk;
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}
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/* Define various data structures for state recording.
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* Some fields are not used due to test simplification.
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*/
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enum tcp_estats_addrtype {
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TCP_ESTATS_ADDRTYPE_IPV4 = 1,
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TCP_ESTATS_ADDRTYPE_IPV6 = 2
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};
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enum tcp_estats_event_type {
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TCP_ESTATS_ESTABLISH,
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TCP_ESTATS_PERIODIC,
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TCP_ESTATS_TIMEOUT,
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TCP_ESTATS_RETRANSMIT_TIMEOUT,
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TCP_ESTATS_RETRANSMIT_OTHER,
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TCP_ESTATS_SYN_RETRANSMIT,
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TCP_ESTATS_SYNACK_RETRANSMIT,
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TCP_ESTATS_TERM,
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TCP_ESTATS_TX_RESET,
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TCP_ESTATS_RX_RESET,
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TCP_ESTATS_WRITE_TIMEOUT,
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TCP_ESTATS_CONN_TIMEOUT,
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TCP_ESTATS_ACK_LATENCY,
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TCP_ESTATS_NEVENTS,
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};
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struct tcp_estats_event {
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int pid;
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int cpu;
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unsigned long ts;
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unsigned int magic;
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enum tcp_estats_event_type event_type;
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};
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/* The below data structure is packed in order for
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* llvm compiler to generate expected code.
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*/
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struct tcp_estats_conn_id {
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unsigned int localaddressType;
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struct {
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unsigned char data[16];
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} localaddress;
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struct {
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unsigned char data[16];
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} remaddress;
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unsigned short localport;
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unsigned short remport;
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} __attribute__((__packed__));
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struct tcp_estats_basic_event {
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struct tcp_estats_event event;
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struct tcp_estats_conn_id conn_id;
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};
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struct bpf_map_def SEC("maps") ev_record_map = {
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.type = BPF_MAP_TYPE_HASH,
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.key_size = sizeof(__u32),
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.value_size = sizeof(struct tcp_estats_basic_event),
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.max_entries = 1024,
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};
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struct dummy_tracepoint_args {
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unsigned long long pad;
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struct sock *sock;
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};
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static __always_inline void tcp_estats_ev_init(struct tcp_estats_event *event,
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enum tcp_estats_event_type type)
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{
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event->magic = TCP_ESTATS_MAGIC;
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event->ts = bpf_ktime_get_ns();
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event->event_type = type;
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}
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static __always_inline void unaligned_u32_set(unsigned char *to, __u8 *from)
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{
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to[0] = _(from[0]);
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to[1] = _(from[1]);
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to[2] = _(from[2]);
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to[3] = _(from[3]);
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}
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static __always_inline void conn_id_ipv4_init(struct tcp_estats_conn_id *conn_id,
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__be32 *saddr, __be32 *daddr)
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{
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conn_id->localaddressType = TCP_ESTATS_ADDRTYPE_IPV4;
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unaligned_u32_set(conn_id->localaddress.data, (__u8 *)saddr);
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unaligned_u32_set(conn_id->remaddress.data, (__u8 *)daddr);
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}
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static __always_inline void conn_id_ipv6_init(struct tcp_estats_conn_id *conn_id,
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__be32 *saddr, __be32 *daddr)
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{
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conn_id->localaddressType = TCP_ESTATS_ADDRTYPE_IPV6;
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unaligned_u32_set(conn_id->localaddress.data, (__u8 *)saddr);
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unaligned_u32_set(conn_id->localaddress.data + sizeof(__u32),
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(__u8 *)(saddr + 1));
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unaligned_u32_set(conn_id->localaddress.data + sizeof(__u32) * 2,
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(__u8 *)(saddr + 2));
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unaligned_u32_set(conn_id->localaddress.data + sizeof(__u32) * 3,
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(__u8 *)(saddr + 3));
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unaligned_u32_set(conn_id->remaddress.data,
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(__u8 *)(daddr));
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unaligned_u32_set(conn_id->remaddress.data + sizeof(__u32),
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(__u8 *)(daddr + 1));
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unaligned_u32_set(conn_id->remaddress.data + sizeof(__u32) * 2,
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(__u8 *)(daddr + 2));
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unaligned_u32_set(conn_id->remaddress.data + sizeof(__u32) * 3,
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(__u8 *)(daddr + 3));
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}
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static __always_inline void tcp_estats_conn_id_init(struct tcp_estats_conn_id *conn_id,
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struct sock *sk)
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{
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conn_id->localport = _(inet_sk(sk)->inet_sport);
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conn_id->remport = _(inet_sk(sk)->inet_dport);
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if (_(sk->sk_family) == AF_INET6)
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conn_id_ipv6_init(conn_id,
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sk->sk_v6_rcv_saddr.s6_addr32,
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sk->sk_v6_daddr.s6_addr32);
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else
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conn_id_ipv4_init(conn_id,
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&inet_sk(sk)->inet_saddr,
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&inet_sk(sk)->inet_daddr);
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}
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static __always_inline void tcp_estats_init(struct sock *sk,
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struct tcp_estats_event *event,
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struct tcp_estats_conn_id *conn_id,
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enum tcp_estats_event_type type)
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{
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tcp_estats_ev_init(event, type);
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tcp_estats_conn_id_init(conn_id, sk);
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}
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static __always_inline void send_basic_event(struct sock *sk,
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enum tcp_estats_event_type type)
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{
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struct tcp_estats_basic_event ev;
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__u32 key = bpf_get_prandom_u32();
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memset(&ev, 0, sizeof(ev));
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tcp_estats_init(sk, &ev.event, &ev.conn_id, type);
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bpf_map_update_elem(&ev_record_map, &key, &ev, BPF_ANY);
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}
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SEC("dummy_tracepoint")
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int _dummy_tracepoint(struct dummy_tracepoint_args *arg)
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{
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if (!arg->sock)
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return 0;
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send_basic_event(arg->sock, TCP_ESTATS_TX_RESET);
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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__u32 _version SEC("version") = 1; /* ignored by tracepoints, required by libbpf.a */
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