[LTP] [PATCH v4 4/4] BPF: Sanity check creating a program

[Cyril Hrubis]

From: Richard Palethorpe <rpalethorpe@suse.com>

Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
Reviewed-by: Cyril Hrubis <chrubis@suse.cz>
---
 runtest/syscalls                           |   1 +
 testcases/kernel/syscalls/bpf/.gitignore   |   1 +
 testcases/kernel/syscalls/bpf/bpf_prog01.c | 162 +++++++++++++++++++++
 3 files changed, 164 insertions(+)
 create mode 100644 testcases/kernel/syscalls/bpf/bpf_prog01.c

diff --git a/runtest/syscalls b/runtest/syscalls
index 6ddfc2178..ec9f5ef6d 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -33,6 +33,7 @@ bind02 bind02
 bind03 bind03
 
 bpf_map01 bpf_map01
+bpf_prog01 bpf_prog01
 
 brk01 brk01
 
diff --git a/testcases/kernel/syscalls/bpf/.gitignore b/testcases/kernel/syscalls/bpf/.gitignore
index f33532484..7eb5f7c92 100644
--- a/testcases/kernel/syscalls/bpf/.gitignore
+++ b/testcases/kernel/syscalls/bpf/.gitignore
@@ -1 +1,2 @@
 bpf_map01
+bpf_prog01
diff --git a/testcases/kernel/syscalls/bpf/bpf_prog01.c b/testcases/kernel/syscalls/bpf/bpf_prog01.c
new file mode 100644
index 000000000..135324efb
--- /dev/null
+++ b/testcases/kernel/syscalls/bpf/bpf_prog01.c
@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2019 Richard Palethorpe <rpalethorpe@suse.com>
+ *
+ * Trivial Extended Berkeley Packet Filter (eBPF) test.
+ *
+ * Sanity check loading and running bytecode.
+ *
+ * Test flow:
+ * 1. Create array map
+ * 2. Load eBPF program
+ * 3. Attach program to socket
+ * 4. Send packet on socket
+ * 5. This should trigger eBPF program which writes to array map
+ * 6. Verify array map was written to
+ */
+
+#include <limits.h>
+#include <string.h>
+#include <stdio.h>
+
+#include "config.h"
+#include "tst_test.h"
+#include "lapi/socket.h"
+#include "lapi/bpf.h"
+
+const char MSG[] = "Ahoj!";
+static char *msg;
+
+/*
+ * The following is a byte code template. We copy it to a guarded buffer and
+ * substitute the runtime value of our map file descriptor.
+ *
+ * r0 - r10 = registers 0 to 10
+ * r0 = return code
+ * r1 - r5 = scratch registers, used for function arguments
+ * r6 - r9 = registers preserved across function calls
+ * fp/r10 = stack frame pointer
+ */
+const struct bpf_insn PROG[] = {
+	/* Load the map FD into r1 (place holder) */
+	BPF_LD_MAP_FD(BPF_REG_1, 0),
+	/* Put (key = 0) on stack and key ptr into r2 */
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),   /* r2 = fp */
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),  /* r2 = r2 - 8 */
+	BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),    /* *r2 = 0 */
+	/* r0 = bpf_map_lookup_elem(r1, r2) */
+	BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
+	/* if r0 == 0 goto exit */
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3),
+	/* Set map[0] = 1 */
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),     /* r1 = r0 */
+	BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 1),     /* *r1 = 1 */
+	BPF_MOV64_IMM(BPF_REG_0, 0),             /* r0 = 0 */
+	BPF_EXIT_INSN(),		         /* return r0 */
+};
+
+static struct bpf_insn *prog;
+static char *log;
+static union bpf_attr *attr;
+
+int load_prog(int fd)
+{
+	prog[0] = BPF_LD_MAP_FD(BPF_REG_1, fd);
+
+	memset(attr, 0, sizeof(*attr));
+	attr->prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+	attr->insns = ptr_to_u64(prog);
+	attr->insn_cnt = ARRAY_SIZE(PROG);
+	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_brk(TFAIL | TTERRNO,
+				"Failed verification: %s",
+				log);
+		} else {
+			tst_brk(TFAIL | TTERRNO, "Failed to load program");
+		}
+	} else {
+		tst_res(TPASS, "Loaded program");
+	}
+
+	return TST_RET;
+}
+
+void setup(void)
+{
+	memcpy(prog, PROG, sizeof(PROG));
+	memcpy(msg, MSG, sizeof(MSG));
+}
+
+void run(void)
+{
+	int map_fd, prog_fd;
+	int sk[2];
+	uint32_t key = 0;
+	uint64_t val;
+
+	memset(attr, 0, sizeof(*attr));
+	attr->map_type = BPF_MAP_TYPE_ARRAY;
+	attr->key_size = 4;
+	attr->value_size = 8;
+	attr->max_entries = 1;
+
+	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);
+
+	TEST(bpf(BPF_MAP_LOOKUP_ELEM, attr, sizeof(*attr)));
+	if (TST_RET == -1) {
+		tst_res(TFAIL | TTERRNO, "array map lookup");
+	} else if (val != 1) {
+		tst_res(TFAIL,
+			"val = %lu, but should be val = 1",
+			val);
+        } else {
+	        tst_res(TPASS, "val = 1");
+	}
+
+	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",
+	.bufs = (struct tst_buffers []) {
+		{&log, .size = BUFSIZ},
+		{&prog, .size = sizeof(PROG)},
+		{&attr, .size = sizeof(*attr)},
+		{&msg, .size = sizeof(MSG)},
+		{},
+	}
+};
-- 
2.21.0