[PATCH] bpf: Allow bpf_skb_event_output for a few prog types

[allanzhang]

    Software event output is only enabled by a few prog types right now (TC,
    LWT out, XDP, sockops). Many other skb based prog types need
    bpf_skb_event_output to produce software event.

    Added socket_filter, cg_skb, sk_skb prog types to generate sw event.

    Test bpf code is generated from code snippet:

    struct TMP {
        uint64_t tmp;
    } tt;
    tt.tmp = 5;
    bpf_perf_event_output(skb, &connection_tracking_event_map, 0,
                          &tt, sizeof(tt));
    return 1;

    the bpf assembly from llvm is:
           0:       b7 02 00 00 05 00 00 00         r2 = 5
           1:       7b 2a f8 ff 00 00 00 00         *(u64 *)(r10 - 8) = r2
           2:       bf a4 00 00 00 00 00 00         r4 = r10
           3:       07 04 00 00 f8 ff ff ff         r4 += -8
           4:       18 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00    r2 = 0ll
           6:       b7 03 00 00 00 00 00 00         r3 = 0
           7:       b7 05 00 00 08 00 00 00         r5 = 8
           8:       85 00 00 00 19 00 00 00         call 25
           9:       b7 00 00 00 01 00 00 00         r0 = 1
          10:       95 00 00 00 00 00 00 00         exit

    Patch 1 is enabling code.
    Patch 2 is fullly covered selftest code.

Signed-off-by: allanzhang <allanzhang@xxxxxxxxxx>
---
 tools/testing/selftests/bpf/test_verifier.c   | 38 +++++++-
 .../selftests/bpf/verifier/event_output.c     | 94 +++++++++++++++++++
 2 files changed, 130 insertions(+), 2 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/verifier/event_output.c

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index c5514daf8865..45ce9dd4323f 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -1,10 +1,13 @@
-// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Testsuite for eBPF verifier
  *
  * Copyright (c) 2014 PLUMgrid, http://plumgrid.com
  * Copyright (c) 2017 Facebook
  * Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
  */
 
 #include <endian.h>
@@ -50,7 +53,7 @@
 #define MAX_INSNS	BPF_MAXINSNS
 #define MAX_TEST_INSNS	1000000
 #define MAX_FIXUPS	8
-#define MAX_NR_MAPS	18
+#define MAX_NR_MAPS	19
 #define MAX_TEST_RUNS	8
 #define POINTER_VALUE	0xcafe4all
 #define TEST_DATA_LEN	64
@@ -84,6 +87,7 @@ struct bpf_test {
 	int fixup_map_array_wo[MAX_FIXUPS];
 	int fixup_map_array_small[MAX_FIXUPS];
 	int fixup_sk_storage_map[MAX_FIXUPS];
+	int fixup_map_event_output[MAX_FIXUPS];
 	const char *errstr;
 	const char *errstr_unpriv;
 	uint32_t retval, retval_unpriv, insn_processed;
@@ -604,6 +608,28 @@ static int create_sk_storage_map(void)
 	return fd;
 }
 
+static int create_event_output_map(void)
+{
+	struct bpf_create_map_attr attr = {
+		.name = "test_map",
+		.map_type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
+		.key_size = 4,
+		.value_size = 4,
+		.max_entries = 1,
+	};
+	int fd, btf_fd;
+
+	btf_fd = load_btf();
+	if (btf_fd < 0)
+		return -1;
+	attr.btf_fd = btf_fd;
+	fd = bpf_create_map_xattr(&attr);
+	close(attr.btf_fd);
+	if (fd < 0)
+		printf("Failed to create event_output\n");
+	return fd;
+}
+
 static char bpf_vlog[UINT_MAX >> 8];
 
 static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
@@ -627,6 +653,7 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
 	int *fixup_map_array_wo = test->fixup_map_array_wo;
 	int *fixup_map_array_small = test->fixup_map_array_small;
 	int *fixup_sk_storage_map = test->fixup_sk_storage_map;
+	int *fixup_map_event_output = test->fixup_map_event_output;
 
 	if (test->fill_helper) {
 		test->fill_insns = calloc(MAX_TEST_INSNS, sizeof(struct bpf_insn));
@@ -788,6 +815,13 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
 			fixup_sk_storage_map++;
 		} while (*fixup_sk_storage_map);
 	}
+	if (*fixup_map_event_output) {
+		map_fds[18] = create_event_output_map();
+		do {
+			prog[*fixup_map_event_output].imm = map_fds[18];
+			fixup_map_event_output++;
+		} while (*fixup_map_event_output);
+	}
 }
 
 static int set_admin(bool admin)
diff --git a/tools/testing/selftests/bpf/verifier/event_output.c b/tools/testing/selftests/bpf/verifier/event_output.c
new file mode 100644
index 000000000000..b25eabcfaa56
--- /dev/null
+++ b/tools/testing/selftests/bpf/verifier/event_output.c
@@ -0,0 +1,94 @@
+/* instructions used to output a skb based software event, produced
+ * from code snippet:
+struct TMP {
+  uint64_t tmp;
+} tt;
+tt.tmp = 5;
+bpf_perf_event_output(skb, &connection_tracking_event_map, 0,
+		      &tt, sizeof(tt));
+return 1;
+
+the bpf assembly from llvm is:
+       0:       b7 02 00 00 05 00 00 00         r2 = 5
+       1:       7b 2a f8 ff 00 00 00 00         *(u64 *)(r10 - 8) = r2
+       2:       bf a4 00 00 00 00 00 00         r4 = r10
+       3:       07 04 00 00 f8 ff ff ff         r4 += -8
+       4:       18 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00    r2 = 0ll
+       6:       b7 03 00 00 00 00 00 00         r3 = 0
+       7:       b7 05 00 00 08 00 00 00         r5 = 8
+       8:       85 00 00 00 19 00 00 00         call 25
+       9:       b7 00 00 00 01 00 00 00         r0 = 1
+      10:       95 00 00 00 00 00 00 00         exit
+
+    The reason I put the code here instead of fill_helpers is that map fixup is
+    against the insns, instead of filled prog.
+*/
+
+#define __PERF_EVENT_INSNS__					\
+	BPF_MOV64_IMM(BPF_REG_2, 5),				\
+	BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -8),		\
+	BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),			\
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -8),			\
+	BPF_LD_MAP_FD(BPF_REG_2, 0),				\
+	BPF_MOV64_IMM(BPF_REG_3, 0),				\
+	BPF_MOV64_IMM(BPF_REG_5, 8),				\
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,		\
+		     BPF_FUNC_perf_event_output),		\
+	BPF_MOV64_IMM(BPF_REG_0, 1),				\
+	BPF_EXIT_INSN(),
+{
+	"perfevent for sockops",
+	.insns = { __PERF_EVENT_INSNS__ },
+	.prog_type = BPF_PROG_TYPE_SOCK_OPS,
+	.fixup_map_event_output = { 4 },
+	.result = ACCEPT,
+	.retval = 1,
+},
+{
+	"perfevent for tc",
+	.insns =  { __PERF_EVENT_INSNS__ },
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+	.fixup_map_event_output = { 4 },
+	.result = ACCEPT,
+	.retval = 1,
+},
+{
+	"perfevent for lwt out",
+	.insns =  { __PERF_EVENT_INSNS__ },
+	.prog_type = BPF_PROG_TYPE_LWT_OUT,
+	.fixup_map_event_output = { 4 },
+	.result = ACCEPT,
+	.retval = 1,
+},
+{
+	"perfevent for xdp",
+	.insns =  { __PERF_EVENT_INSNS__ },
+	.prog_type = BPF_PROG_TYPE_XDP,
+	.fixup_map_event_output = { 4 },
+	.result = ACCEPT,
+	.retval = 1,
+},
+{
+	"perfevent for socket filter",
+	.insns =  { __PERF_EVENT_INSNS__ },
+	.prog_type = BPF_PROG_TYPE_SOCKET_FILTER,
+	.fixup_map_event_output = { 4 },
+	.result = ACCEPT,
+	.retval = 1,
+},
+{
+	"perfevent for sk_skb",
+	.insns =  { __PERF_EVENT_INSNS__ },
+	.prog_type = BPF_PROG_TYPE_SK_SKB,
+	.fixup_map_event_output = { 4 },
+	.result = ACCEPT,
+	.retval = 1,
+},
+{
+	"perfevent for cgroup skb",
+	.insns =  { __PERF_EVENT_INSNS__ },
+	.prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+	.fixup_map_event_output = { 4 },
+	.result = ACCEPT,
+	.retval = 1,
+},
-- 
2.22.0.410.gd8fdbe21b5-goog