[LTP] [PATCH v3] BPF: Regression test for 64bit arithmetic
Cyril Hrubis
chrubis@suse.cz
Thu Sep 12 16:56:37 CEST 2019
Hi!
A few minor points below, I guess I can fix these before pushing as
well.
> Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
> Reviewed-by: Jan Stancek <jstancek@redhat.com>
> Reviewed-by: Cyril Hrubis <chrubis@suse.cz>
> ---
>
> V3: Rebased on master and included line numbers in instructions
>
> Capability patch has not been applied to master at time of rebase.
>
> include/lapi/bpf.h | 27 +++
> runtest/syscalls | 1 +
> testcases/kernel/syscalls/bpf/.gitignore | 1 +
> testcases/kernel/syscalls/bpf/bpf_prog02.c | 182 +++++++++++++++++++++
> 4 files changed, 211 insertions(+)
> create mode 100644 testcases/kernel/syscalls/bpf/bpf_prog02.c
>
> diff --git a/include/lapi/bpf.h b/include/lapi/bpf.h
> index 122eb5469..03073b45e 100644
> --- a/include/lapi/bpf.h
> +++ b/include/lapi/bpf.h
> @@ -18,7 +18,9 @@
> /* Start copy from linux/bpf_(common).h */
> #define BPF_CLASS(code) ((code) & 0x07)
> #define BPF_LD 0x00
> +#define BPF_LDX 0x01
> #define BPF_ST 0x02
> +#define BPF_STX 0x03
> #define BPF_JMP 0x05
>
> #define BPF_SIZE(code) ((code) & 0x18)
> @@ -30,6 +32,7 @@
>
> #define BPF_OP(code) ((code) & 0xf0)
> #define BPF_ADD 0x00
> +#define BPF_SUB 0x10
>
> #define BPF_JEQ 0x10
>
> @@ -432,6 +435,14 @@ enum bpf_func_id {
>
> /* Start copy from tools/include/filter.h */
>
> +#define BPF_ALU64_REG(OP, DST, SRC) \
> + ((struct bpf_insn) { \
> + .code = BPF_ALU64 | BPF_OP(OP) | BPF_X, \
> + .dst_reg = DST, \
> + .src_reg = SRC, \
> + .off = 0, \
> + .imm = 0 })
> +
> #define BPF_ALU64_IMM(OP, DST, IMM) \
> ((struct bpf_insn) { \
> .code = BPF_ALU64 | BPF_OP(OP) | BPF_K, \
> @@ -477,6 +488,22 @@ enum bpf_func_id {
> .off = OFF, \
> .imm = IMM })
>
> +#define BPF_LDX_MEM(SIZE, DST, SRC, OFF) \
> + ((struct bpf_insn) { \
> + .code = BPF_LDX | BPF_SIZE(SIZE) | BPF_MEM, \
> + .dst_reg = DST, \
> + .src_reg = SRC, \
> + .off = OFF, \
> + .imm = 0 })
> +
> +#define BPF_STX_MEM(SIZE, DST, SRC, OFF) \
> + ((struct bpf_insn) { \
> + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_MEM, \
> + .dst_reg = DST, \
> + .src_reg = SRC, \
> + .off = OFF, \
> + .imm = 0 })
> +
> #define BPF_JMP_IMM(OP, DST, IMM, OFF) \
> ((struct bpf_insn) { \
> .code = BPF_JMP | BPF_OP(OP) | BPF_K, \
> diff --git a/runtest/syscalls b/runtest/syscalls
> index 874ae4d4f..4e6310193 100644
> --- a/runtest/syscalls
> +++ b/runtest/syscalls
> @@ -34,6 +34,7 @@ bind03 bind03
>
> bpf_map01 bpf_map01
> bpf_prog01 bpf_prog01
> +bpf_prog02 bpf_prog02
>
> brk01 brk01
>
> diff --git a/testcases/kernel/syscalls/bpf/.gitignore b/testcases/kernel/syscalls/bpf/.gitignore
> index 7eb5f7c92..1704f9841 100644
> --- a/testcases/kernel/syscalls/bpf/.gitignore
> +++ b/testcases/kernel/syscalls/bpf/.gitignore
> @@ -1,2 +1,3 @@
> bpf_map01
> bpf_prog01
> +bpf_prog02
> diff --git a/testcases/kernel/syscalls/bpf/bpf_prog02.c b/testcases/kernel/syscalls/bpf/bpf_prog02.c
> new file mode 100644
> index 000000000..dc8b92f00
> --- /dev/null
> +++ b/testcases/kernel/syscalls/bpf/bpf_prog02.c
> @@ -0,0 +1,182 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2019 Richard Palethorpe <rpalethorpe@suse.com>
> + *
> + * Check if eBPF can do arithmetic with 64bits. This targets a specific
> + * regression which only effects unprivileged users who are subject to extra
> + * pointer arithmetic checks during verification.
> + *
> + * Fixed by commit 3612af783cf52c74a031a2f11b82247b2599d3cd.
> + * https://new.blog.cloudflare.com/ebpf-cant-count/
> + *
> + * This test is very similar in structure to bpf_prog01 which is better
> + * annotated.
> + */
> +
> +#include <limits.h>
> +#include <string.h>
> +#include <stdio.h>
> +
> +#include "config.h"
> +#include "tst_test.h"
> +#include "tst_capability.h"
> +#include "lapi/socket.h"
> +#include "lapi/bpf.h"
> +
> +#define A64INT (((uint64_t)1) << 60)
> +
> +const char MSG[] = "Ahoj!";
> +static char *msg;
> +
> +static char *log;
> +static uint32_t *key;
> +static uint64_t *val;
> +static union bpf_attr *attr;
> +
> +static int load_prog(int fd)
> +{
> + struct bpf_insn *prog;
> + struct bpf_insn insn[] = {
> + BPF_MOV64_IMM(BPF_REG_6, 1), /* 0: r6 = 1 */
> +
> + BPF_LD_MAP_FD(BPF_REG_1, fd), /* 1: r1 = &fd */
> + BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), /* 3: r2 = fp */
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8), /* 4: r2 = r2 - 8 */
> + BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0), /* 5: *r2 = 0 */
> + BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),/* 6: map_lookup_elem */
> + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 17), /* 7: if(!r0) goto 25 */
> + BPF_MOV64_REG(BPF_REG_3, BPF_REG_0), /* 8: r3 = r0 */
> + BPF_LD_IMM64(BPF_REG_4, A64INT), /* 9: r4 = 2^61 */
> + BPF_ALU64_REG(BPF_ADD, BPF_REG_4, BPF_REG_6), /* 11: r4 += r6 */
> + BPF_STX_MEM(BPF_DW, BPF_REG_3, BPF_REG_4, 0), /* 12: *r3 = r4 */
> +
> + BPF_LD_MAP_FD(BPF_REG_1, fd), /* 13: r1 = &fd */
> + BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), /* 15: r2 = fp */
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8), /* 16: r2 = r2 - 8 */
> + BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 1), /* 17: *r2 = 1 */
> + BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),/* 18: map_lookup_elem */
> + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 5), /* 19: if(!r0) goto 25 */
> + BPF_MOV64_REG(BPF_REG_3, BPF_REG_0), /* 20: r3 = r0 */
> + BPF_LD_IMM64(BPF_REG_4, A64INT), /* 21: r4 = 2^61 */
> + BPF_ALU64_REG(BPF_SUB, BPF_REG_4, BPF_REG_6), /* 23: r4 -= r6 */
> + BPF_STX_MEM(BPF_DW, BPF_REG_3, BPF_REG_4, 0), /* 24: *r3 = r4 */
> +
> + BPF_MOV64_IMM(BPF_REG_0, 0), /* 25: r0 = 0 */
> + BPF_EXIT_INSN(), /* 26: return r0 */
> + };
> +
> + /* Leaks memory when -i is specified */
> + prog = tst_alloc(sizeof(insn));
Why not just declare the prog static? Then we could do:
if (!prog)
prog = tst_alloc(sizeof(insn));
> + memcpy(prog, insn, sizeof(insn));
> +
> + memset(attr, 0, sizeof(*attr));
> + attr->prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
> + attr->insns = ptr_to_u64(prog);
> + attr->insn_cnt = ARRAY_SIZE(insn);
> + attr->license = ptr_to_u64("GPL");
> + attr->log_buf = ptr_to_u64(log);
> + attr->log_size = BUFSIZ;
> + attr->log_level = 1;
> +
> + TEST(bpf(BPF_PROG_LOAD, attr, sizeof(*attr)));
> + if (TST_RET == -1) {
> + if (log[0] != 0) {
> + tst_res(TINFO, "Verification log:");
> + fputs(log, stderr);
I guess that we can do tst_res(TINFO, "Verification log:\n%s", log); instead.
> + tst_brk(TBROK | TTERRNO, "Failed verification");
> + } else {
> + tst_brk(TBROK | TTERRNO, "Failed to load program");
> + }
> + }
> +
> + return TST_RET;
> +}
> +
> +static void setup(void)
> +{
> + memcpy(msg, MSG, sizeof(MSG));
> +}
> +
> +static void run(void)
> +{
> + int map_fd, prog_fd;
> + int sk[2];
> +
> + memset(attr, 0, sizeof(*attr));
> + attr->map_type = BPF_MAP_TYPE_ARRAY;
> + attr->key_size = 4;
> + attr->value_size = 8;
> + attr->max_entries = 2;
> +
> + TEST(bpf(BPF_MAP_CREATE, attr, sizeof(*attr)));
> + if (TST_RET == -1) {
> + if (TST_ERR == EPERM) {
> + tst_brk(TCONF | TTERRNO,
> + "bpf() requires CAP_SYS_ADMIN on this system");
> + } else {
> + tst_brk(TBROK | TTERRNO, "Failed to create array map");
> + }
> + }
> + map_fd = TST_RET;
> +
> + prog_fd = load_prog(map_fd);
> +
> + SAFE_SOCKETPAIR(AF_UNIX, SOCK_DGRAM, 0, sk);
> + SAFE_SETSOCKOPT(sk[1], SOL_SOCKET, SO_ATTACH_BPF,
> + &prog_fd, sizeof(prog_fd));
> +
> + SAFE_WRITE(1, sk[0], msg, sizeof(MSG));
> +
> + memset(attr, 0, sizeof(*attr));
> + attr->map_fd = map_fd;
> + attr->key = ptr_to_u64(key);
> + attr->value = ptr_to_u64(val);
> + *key = 0;
> +
> + TEST(bpf(BPF_MAP_LOOKUP_ELEM, attr, sizeof(*attr)));
> + if (TST_RET == -1) {
> + tst_res(TFAIL | TTERRNO, "array map lookup");
> + } else if (*val != A64INT + 1) {
> + tst_res(TFAIL,
> + "val = %lu, but should be val = %lu + 1",
> + *val, A64INT);
> + } else {
> + tst_res(TPASS, "val = %lu + 1", A64INT);
> + }
Wrong indentation, also I do not fancy this if else maze. I guess that
we can can safely do goto exit; if map lookup fails that would point
right before the SAFE_CLOSE() block.
> + *key = 1;
> +
> + TEST(bpf(BPF_MAP_LOOKUP_ELEM, attr, sizeof(*attr)));
> + if (TST_RET == -1) {
> + tst_res(TFAIL | TTERRNO, "array map lookup");
> + } else if (*val != A64INT - 1) {
> + tst_res(TFAIL,
> + "val = %lu, but should be val = %lu - 1",
> + *val, A64INT);
> + } else {
> + tst_res(TPASS, "val = %lu - 1", A64INT);
> + }
Here as well.
> + SAFE_CLOSE(prog_fd);
> + SAFE_CLOSE(map_fd);
> + SAFE_CLOSE(sk[0]);
> + SAFE_CLOSE(sk[1]);
> +}
> +
> +static struct tst_test test = {
> + .setup = setup,
> + .test_all = run,
> + .min_kver = "3.18",
> + .caps = (struct tst_cap []) {
> + TST_CAP(TST_CAP_DROP, CAP_SYS_ADMIN),
> + {}
> + },
> + .bufs = (struct tst_buffers []) {
> + {&key, .size = sizeof(*key)},
> + {&val, .size = sizeof(*val)},
> + {&log, .size = BUFSIZ},
> + {&attr, .size = sizeof(*attr)},
> + {&msg, .size = sizeof(MSG)},
> + {},
> + }
> +};
> --
> 2.22.1
>
--
Cyril Hrubis
chrubis@suse.cz
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