[LTP] [PATCH v3] BPF: Regression test for 64bit arithmetic
Richard Palethorpe
rpalethorpe@suse.com
Wed Sep 11 11:54:22 CEST 2019
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));
+ 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);
+ 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);
+ }
+
+ *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);
+ }
+
+ 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
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