[LTP] [PATCH v3 0/4] BPF refactor and add bpf_prog05

[LTP] [PATCH v3 0/4] BPF refactor and add bpf_prog05

[Richard Palethorpe]

Hello,

V3:

* constify and add attributes

* replace insn builder with BPF_MAP_ARRAY_STX macro to insert multiple
  instructions.

V2:

* Added a number of helper functions to bpf_common and used them on
  all tests.

* Added some instruction concatenation helpers, but only used these on
  bpf_prog05 as they don't seem to make the other tests better to
  read.

* Further shorten bpf_prog05 by using a generic expect function

Richard Palethorpe (4):
  lapi/bpf: Add /= and %=
  bpf: Add map_array helper functions/macro and constify
  bpf: Add helper to run socket programs
  bpf: Check truncation on 32bit div/mod by zero

 include/lapi/bpf.h                         |   2 +
 runtest/cve                                |   1 +
 runtest/syscalls                           |   1 +
 testcases/kernel/syscalls/bpf/.gitignore   |   1 +
 testcases/kernel/syscalls/bpf/bpf_common.c |  64 ++++++--
 testcases/kernel/syscalls/bpf/bpf_common.h |  53 +++++-
 testcases/kernel/syscalls/bpf/bpf_prog01.c |  32 +---
 testcases/kernel/syscalls/bpf/bpf_prog02.c |  54 ++-----
 testcases/kernel/syscalls/bpf/bpf_prog03.c |  32 +---
 testcases/kernel/syscalls/bpf/bpf_prog04.c |  17 +-
 testcases/kernel/syscalls/bpf/bpf_prog05.c | 177 +++++++++++++++++++++
 11 files changed, 308 insertions(+), 126 deletions(-)
 create mode 100644 testcases/kernel/syscalls/bpf/bpf_prog05.c

-- 
2.31.1

[LTP] [PATCH v3 1/4] lapi/bpf: Add /= and %=

[Richard Palethorpe]

Add div and mod instructions.

Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
---
 include/lapi/bpf.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/lapi/bpf.h b/include/lapi/bpf.h
index f27a92146..5ae25293b 100644
--- a/include/lapi/bpf.h
+++ b/include/lapi/bpf.h
@@ -37,8 +37,10 @@
 #define BPF_OP(code)    ((code) & 0xf0)
 #define		BPF_ADD		0x00
 #define		BPF_SUB		0x10
+#define		BPF_DIV		0x30
 #define		BPF_LSH		0x60
 #define		BPF_RSH		0x70
+#define		BPF_MOD		0x90
 
 #define		BPF_JEQ		0x10
 
-- 
2.31.1

[LTP] [PATCH v3 2/4] bpf: Add map_array helper functions/macro and constify

[Richard Palethorpe]

We usually just create an array map with standard key and value
size. Then fetch some values from the array. So we can create some
standard functions for this.

The byte code which stores the values in the map can also be
extracted into a macro. So a macro has been added, however it is only
used in the new bpf_prog05 test. The old tests do some pointer
arithmetic on the map call return value to trigger bugs. They could be
rewritten, but then would need verifying.

This also adds some extra const checks and attributes.

Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
---
 testcases/kernel/syscalls/bpf/bpf_common.c | 49 ++++++++++++++++----
 testcases/kernel/syscalls/bpf/bpf_common.h | 53 ++++++++++++++++++++--
 testcases/kernel/syscalls/bpf/bpf_prog01.c | 25 +++-------
 testcases/kernel/syscalls/bpf/bpf_prog02.c | 47 +++++--------------
 testcases/kernel/syscalls/bpf/bpf_prog03.c | 25 ++--------
 testcases/kernel/syscalls/bpf/bpf_prog04.c |  8 +---
 6 files changed, 112 insertions(+), 95 deletions(-)

diff --git a/testcases/kernel/syscalls/bpf/bpf_common.c b/testcases/kernel/syscalls/bpf/bpf_common.c
index fd299b73d..42c72b975 100644
--- a/testcases/kernel/syscalls/bpf/bpf_common.c
+++ b/testcases/kernel/syscalls/bpf/bpf_common.c
@@ -28,7 +28,7 @@ void rlimit_bump_memlock(void)
 	}
 }
 
-int bpf_map_create(union bpf_attr *attr)
+int bpf_map_create(union bpf_attr *const attr)
 {
 	int ret;
 
@@ -48,12 +48,45 @@ int bpf_map_create(union bpf_attr *attr)
 	return ret;
 }
 
-void bpf_init_prog_attr(union bpf_attr *attr, const struct bpf_insn *prog,
-	size_t prog_size, char *log_buf, size_t log_size)
+int bpf_map_array_create(const uint32_t max_entries)
+{
+	union bpf_attr map_attr = {
+		.map_type = BPF_MAP_TYPE_ARRAY,
+		.key_size = 4,
+		.value_size = 8,
+		.max_entries = max_entries,
+		.map_flags = 0
+	};
+
+	return bpf_map_create(&map_attr);
+}
+
+void bpf_map_array_get(const int map_fd,
+		       const uint32_t *const array_indx,
+		       uint64_t *const array_val)
+{
+	union bpf_attr elem_attr = {
+		.map_fd = map_fd,
+		.key = ptr_to_u64(array_indx),
+		.value = ptr_to_u64(array_val),
+		.flags = 0
+	};
+	const int ret = bpf(BPF_MAP_LOOKUP_ELEM, &elem_attr, sizeof(elem_attr));
+
+        if (ret) {
+		tst_brk(TBROK | TTERRNO,
+			"Failed array map lookup: [%"PRIu32, *array_indx);
+	}
+}
+
+void bpf_init_prog_attr(union bpf_attr *const attr,
+			const struct bpf_insn *const prog,
+			const size_t prog_size, char *const log_buf,
+			const size_t log_size)
 {
 	static struct bpf_insn *buf;
 	static size_t buf_size;
-	size_t prog_len = prog_size / sizeof(*prog);
+	const size_t prog_len = prog_size / sizeof(*prog);
 
 	/* all guarded buffers will be free()d automatically by LTP library */
 	if (!buf || prog_size > buf_size) {
@@ -72,12 +105,10 @@ void bpf_init_prog_attr(union bpf_attr *attr, const struct bpf_insn *prog,
 	attr->log_level = 1;
 }
 
-int bpf_load_prog(union bpf_attr *attr, const char *log)
+int bpf_load_prog(union bpf_attr *const attr, const char *const log)
 {
-	int ret;
-
-	ret = TST_RETRY_FUNC(bpf(BPF_PROG_LOAD, attr, sizeof(*attr)),
-		TST_RETVAL_GE0);
+	const int ret = TST_RETRY_FUNC(bpf(BPF_PROG_LOAD, attr, sizeof(*attr)),
+				       TST_RETVAL_GE0);
 
 	if (ret >= 0) {
 		tst_res(TPASS, "Loaded program");
diff --git a/testcases/kernel/syscalls/bpf/bpf_common.h b/testcases/kernel/syscalls/bpf/bpf_common.h
index d36a2b09f..b4d94d90c 100644
--- a/testcases/kernel/syscalls/bpf/bpf_common.h
+++ b/testcases/kernel/syscalls/bpf/bpf_common.h
@@ -6,12 +6,57 @@
 #ifndef LTP_BPF_COMMON_H
 #define LTP_BPF_COMMON_H
 
+#include <sys/types.h>
+#include <inttypes.h>
+
+#include "lapi/bpf.h"
+
 #define BPF_MEMLOCK_ADD (2*1024*1024)
 
+/* map[array_indx] = reg_to_save
+ *
+ * Inserts the following instructions
+ *
+ * r1 = map_fd
+ * r2 = fp
+ * r2 = r2 - 4
+ * r2 = array_indx
+ * call map_lookup_elem(r1, r2)
+ * if r0 != 0 goto pc+1
+ * exit
+ * *r0 = reg_to_save
+ *
+ */
+#define BPF_MAP_ARRAY_STX(map_fd, array_indx, reg_to_save)\
+	BPF_LD_MAP_FD(BPF_REG_1, map_fd),		\
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),		\
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4),		\
+	BPF_ST_MEM(BPF_W, BPF_REG_2, 0, array_indx),	\
+	BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),	\
+	BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),		\
+	BPF_EXIT_INSN(),				\
+	BPF_STX_MEM(BPF_DW, BPF_REG_0, reg_to_save, 0)
+
 void rlimit_bump_memlock(void);
-int bpf_map_create(union bpf_attr *attr);
-void bpf_init_prog_attr(union bpf_attr *attr, const struct bpf_insn *prog,
-	size_t prog_size, char *log_buf, size_t log_size);
-int bpf_load_prog(union bpf_attr *attr, const char *log);
+
+int bpf_map_create(union bpf_attr *const attr)
+	__attribute__((nonnull, warn_unused_result));
+int bpf_map_array_create(const uint32_t max_entries)
+	__attribute__((warn_unused_result));
+void bpf_map_array_get(const int map_fd,
+		       const uint32_t *const array_indx,
+		       uint64_t *const array_val)
+	__attribute__((nonnull));
+
+void bpf_init_prog_attr(union bpf_attr *const attr,
+			const struct bpf_insn *const prog,
+			const size_t prog_size,
+			char *const log_buf, const size_t log_size)
+	__attribute__((nonnull));
+int bpf_load_prog(union bpf_attr *const attr, const char *const log)
+	__attribute__((nonnull, warn_unused_result));
+void bpf_run_prog(const int prog_fd,
+		  const char *const msg, const size_t msg_len)
+	__attribute__((nonnull));
 
 #endif
diff --git a/testcases/kernel/syscalls/bpf/bpf_prog01.c b/testcases/kernel/syscalls/bpf/bpf_prog01.c
index 966bf2092..ac57b24b5 100644
--- a/testcases/kernel/syscalls/bpf/bpf_prog01.c
+++ b/testcases/kernel/syscalls/bpf/bpf_prog01.c
@@ -83,14 +83,7 @@ void run(void)
 	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;
-
-	map_fd = bpf_map_create(attr);
-
+	map_fd = bpf_map_array_create(1);
 	prog_fd = load_prog(map_fd);
 
 	SAFE_SOCKETPAIR(AF_UNIX, SOCK_DGRAM, 0, sk);
@@ -99,15 +92,12 @@ void run(void)
 
 	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);
+	SAFE_CLOSE(prog_fd);
+	SAFE_CLOSE(sk[0]);
+	SAFE_CLOSE(sk[1]);
 
-	TEST(bpf(BPF_MAP_LOOKUP_ELEM, attr, sizeof(*attr)));
-	if (TST_RET == -1) {
-		tst_res(TFAIL | TTERRNO, "array map lookup");
-	} else if (val != 1) {
+        bpf_map_array_get(map_fd, &key, &val);
+	if (val != 1) {
 		tst_res(TFAIL,
 			"val = %lu, but should be val = 1",
 			val);
@@ -115,10 +105,7 @@ void run(void)
 	        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 = {
diff --git a/testcases/kernel/syscalls/bpf/bpf_prog02.c b/testcases/kernel/syscalls/bpf/bpf_prog02.c
index eeba16a54..4558153ea 100644
--- a/testcases/kernel/syscalls/bpf/bpf_prog02.c
+++ b/testcases/kernel/syscalls/bpf/bpf_prog02.c
@@ -81,14 +81,7 @@ 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;
-
-	map_fd = bpf_map_create(attr);
-
+	map_fd = bpf_map_array_create(2);
 	prog_fd = load_prog(map_fd);
 
 	SAFE_SOCKETPAIR(AF_UNIX, SOCK_DGRAM, 0, sk);
@@ -97,49 +90,31 @@ static void run(void)
 
 	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");
-		goto exit;
-	}
+	SAFE_CLOSE(prog_fd);
+	SAFE_CLOSE(sk[0]);
+	SAFE_CLOSE(sk[1]);
 
+        *key = 0;
+	bpf_map_array_get(map_fd, key, val);
 	if (*val != A64INT + 1) {
 		tst_res(TFAIL,
 			"val = %"PRIu64", but should be val = %"PRIu64" + 1",
 			*val, A64INT);
-		goto exit;
+	} else {
+		tst_res(TPASS, "val = %"PRIu64" + 1", A64INT);
 	}
 
-	tst_res(TPASS, "val = %"PRIu64" + 1", A64INT);
-
 	*key = 1;
-
-	TEST(bpf(BPF_MAP_LOOKUP_ELEM, attr, sizeof(*attr)));
-	if (TST_RET == -1) {
-		tst_res(TFAIL | TTERRNO, "array map lookup");
-		goto exit;
-	}
-
+	bpf_map_array_get(map_fd, key, val);
 	if (*val != A64INT - 1) {
 		tst_res(TFAIL,
 			"val = %"PRIu64", but should be val = %"PRIu64" - 1",
 			*val, A64INT);
-		goto exit;
+	} else {
+		tst_res(TPASS, "val = %"PRIu64" - 1", A64INT);
 	}
 
-	tst_res(TPASS, "val = %"PRIu64" - 1", A64INT);
-
-exit:
-	SAFE_CLOSE(prog_fd);
 	SAFE_CLOSE(map_fd);
-	SAFE_CLOSE(sk[0]);
-	SAFE_CLOSE(sk[1]);
 }
 
 static struct tst_test test = {
diff --git a/testcases/kernel/syscalls/bpf/bpf_prog03.c b/testcases/kernel/syscalls/bpf/bpf_prog03.c
index 5b8a394e8..1195ddc2c 100644
--- a/testcases/kernel/syscalls/bpf/bpf_prog03.c
+++ b/testcases/kernel/syscalls/bpf/bpf_prog03.c
@@ -119,13 +119,7 @@ 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 = 32;
-
-	map_fd = bpf_map_create(attr);
+	map_fd = bpf_map_array_create(32);
 
 	memset(attr, 0, sizeof(*attr));
 	attr->map_fd = map_fd;
@@ -148,22 +142,13 @@ static void run(void)
 			&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
-		tst_res(TINFO, "Pointer offset was 0x%"PRIx64, *val);
-
 	SAFE_CLOSE(sk[0]);
 	SAFE_CLOSE(sk[1]);
 	SAFE_CLOSE(prog_fd);
+
+	*key = 0;
+	bpf_map_array_get(map_fd, key, val);
+	tst_res(TINFO, "Pointer offset was 0x%"PRIx64, *val);
 exit:
 	SAFE_CLOSE(map_fd);
 }
diff --git a/testcases/kernel/syscalls/bpf/bpf_prog04.c b/testcases/kernel/syscalls/bpf/bpf_prog04.c
index 799fcb52d..1a1ee0f04 100644
--- a/testcases/kernel/syscalls/bpf/bpf_prog04.c
+++ b/testcases/kernel/syscalls/bpf/bpf_prog04.c
@@ -94,13 +94,7 @@ 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 = 1;
-
-	map_fd = bpf_map_create(attr);
+	map_fd = bpf_map_array_create(1);
 	prog_fd = load_prog(map_fd);
 
 	if (prog_fd >= 0) {
-- 
2.31.1

[LTP] [PATCH v3 2/4] bpf: Add map_array helper functions/macro and constify

[Cyril Hrubis]

Hi!
> +	const int ret = bpf(BPF_MAP_LOOKUP_ELEM, &elem_attr, sizeof(elem_attr));
> +
> +        if (ret) {

Fixed these spaces wrongly used for indentation.

> +		tst_brk(TBROK | TTERRNO,
> +			"Failed array map lookup: [%"PRIu32, *array_indx);

And also this message. There was missing ] at the end of the string and
I've also added the fd=%i to the message as well.

And pushed along with the rest of the patchset, thanks.

-- 
Cyril Hrubis
chrubis@suse.cz

[LTP] [PATCH v3 3/4] bpf: Add helper to run socket programs

[Richard Palethorpe]

So far we always trigger the BPF programs the same way.

Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
---
 testcases/kernel/syscalls/bpf/bpf_common.c | 15 +++++++++++++++
 testcases/kernel/syscalls/bpf/bpf_prog01.c | 11 +----------
 testcases/kernel/syscalls/bpf/bpf_prog02.c | 11 +----------
 testcases/kernel/syscalls/bpf/bpf_prog03.c |  9 +--------
 testcases/kernel/syscalls/bpf/bpf_prog04.c |  9 +--------
 5 files changed, 19 insertions(+), 36 deletions(-)

diff --git a/testcases/kernel/syscalls/bpf/bpf_common.c b/testcases/kernel/syscalls/bpf/bpf_common.c
index 42c72b975..8a324a8fa 100644
--- a/testcases/kernel/syscalls/bpf/bpf_common.c
+++ b/testcases/kernel/syscalls/bpf/bpf_common.c
@@ -124,3 +124,18 @@ int bpf_load_prog(union bpf_attr *const attr, const char *const log)
 	tst_brk(TBROK | TERRNO, "Failed to load program");
 	return ret;
 }
+
+void bpf_run_prog(const int prog_fd,
+		  const char *const msg, const size_t msg_len)
+{
+	int sk[2];
+
+	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, msg_len);
+
+	SAFE_CLOSE(sk[0]);
+	SAFE_CLOSE(sk[1]);
+}
diff --git a/testcases/kernel/syscalls/bpf/bpf_prog01.c b/testcases/kernel/syscalls/bpf/bpf_prog01.c
index ac57b24b5..1d5d04556 100644
--- a/testcases/kernel/syscalls/bpf/bpf_prog01.c
+++ b/testcases/kernel/syscalls/bpf/bpf_prog01.c
@@ -79,22 +79,13 @@ void setup(void)
 void run(void)
 {
 	int map_fd, prog_fd;
-	int sk[2];
 	uint32_t key = 0;
 	uint64_t val;
 
 	map_fd = bpf_map_array_create(1);
 	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));
-
+	bpf_run_prog(prog_fd, msg, sizeof(MSG));
 	SAFE_CLOSE(prog_fd);
-	SAFE_CLOSE(sk[0]);
-	SAFE_CLOSE(sk[1]);
 
         bpf_map_array_get(map_fd, &key, &val);
 	if (val != 1) {
diff --git a/testcases/kernel/syscalls/bpf/bpf_prog02.c b/testcases/kernel/syscalls/bpf/bpf_prog02.c
index 4558153ea..9f6acca60 100644
--- a/testcases/kernel/syscalls/bpf/bpf_prog02.c
+++ b/testcases/kernel/syscalls/bpf/bpf_prog02.c
@@ -79,20 +79,11 @@ static void setup(void)
 static void run(void)
 {
 	int map_fd, prog_fd;
-	int sk[2];
 
 	map_fd = bpf_map_array_create(2);
 	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));
-
+	bpf_run_prog(prog_fd, msg, sizeof(MSG));
 	SAFE_CLOSE(prog_fd);
-	SAFE_CLOSE(sk[0]);
-	SAFE_CLOSE(sk[1]);
 
         *key = 0;
 	bpf_map_array_get(map_fd, key, val);
diff --git a/testcases/kernel/syscalls/bpf/bpf_prog03.c b/testcases/kernel/syscalls/bpf/bpf_prog03.c
index 1195ddc2c..9a7af7f4c 100644
--- a/testcases/kernel/syscalls/bpf/bpf_prog03.c
+++ b/testcases/kernel/syscalls/bpf/bpf_prog03.c
@@ -117,7 +117,6 @@ static void setup(void)
 static void run(void)
 {
 	int map_fd, prog_fd;
-	int sk[2];
 
 	map_fd = bpf_map_array_create(32);
 
@@ -137,13 +136,7 @@ static void run(void)
 
 	tst_res(TFAIL, "Loaded bad eBPF, now we will run it and maybe crash");
 
-	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));
-	SAFE_CLOSE(sk[0]);
-	SAFE_CLOSE(sk[1]);
+	bpf_run_prog(prog_fd, msg, sizeof(MSG));
 	SAFE_CLOSE(prog_fd);
 
 	*key = 0;
diff --git a/testcases/kernel/syscalls/bpf/bpf_prog04.c b/testcases/kernel/syscalls/bpf/bpf_prog04.c
index 1a1ee0f04..09d0cc468 100644
--- a/testcases/kernel/syscalls/bpf/bpf_prog04.c
+++ b/testcases/kernel/syscalls/bpf/bpf_prog04.c
@@ -92,7 +92,6 @@ static void setup(void)
 static void run(void)
 {
 	int map_fd, prog_fd;
-	int sk[2];
 
 	map_fd = bpf_map_array_create(1);
 	prog_fd = load_prog(map_fd);
@@ -100,13 +99,7 @@ static void run(void)
 	if (prog_fd >= 0) {
 		tst_res(TFAIL, "Malicious eBPF code passed verification. "
 			"Now let's try crashing the kernel.");
-		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));
-		SAFE_CLOSE(sk[0]);
-		SAFE_CLOSE(sk[1]);
+		bpf_run_prog(prog_fd, msg, sizeof(MSG));
 	}
 
 	if (prog_fd >= 0)
-- 
2.31.1

[LTP] [PATCH v3 4/4] bpf: Check truncation on 32bit div/mod by zero

[Richard Palethorpe]

Add a test which checks for a number of issues surrounding division by
zero.

Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
---
 runtest/cve                                |   1 +
 runtest/syscalls                           |   1 +
 testcases/kernel/syscalls/bpf/.gitignore   |   1 +
 testcases/kernel/syscalls/bpf/bpf_prog05.c | 177 +++++++++++++++++++++
 4 files changed, 180 insertions(+)
 create mode 100644 testcases/kernel/syscalls/bpf/bpf_prog05.c

diff --git a/runtest/cve b/runtest/cve
index f650854f9..3beb88bb0 100644
--- a/runtest/cve
+++ b/runtest/cve
@@ -61,3 +61,4 @@ cve-2020-11494 pty04
 cve-2020-14386 sendto03
 cve-2020-14416 pty03
 cve-2020-29373 io_uring02
+cve-2021-3444 bpf_prog05
diff --git a/runtest/syscalls b/runtest/syscalls
index 816c01bf6..aa7fa24dd 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -42,6 +42,7 @@ bpf_prog01 bpf_prog01
 bpf_prog02 bpf_prog02
 bpf_prog03 bpf_prog03
 bpf_prog04 bpf_prog04
+bpf_prog05 bpf_prog05
 
 brk01 brk01
 brk02 brk02
diff --git a/testcases/kernel/syscalls/bpf/.gitignore b/testcases/kernel/syscalls/bpf/.gitignore
index 74742c0cd..42365cef5 100644
--- a/testcases/kernel/syscalls/bpf/.gitignore
+++ b/testcases/kernel/syscalls/bpf/.gitignore
@@ -3,3 +3,4 @@ bpf_prog01
 bpf_prog02
 bpf_prog03
 bpf_prog04
+bpf_prog05
diff --git a/testcases/kernel/syscalls/bpf/bpf_prog05.c b/testcases/kernel/syscalls/bpf/bpf_prog05.c
new file mode 100644
index 000000000..b8a5e0278
--- /dev/null
+++ b/testcases/kernel/syscalls/bpf/bpf_prog05.c
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2021 SUSE LLC <rpalethorpe@suse.com>
+ */
+
+/*\
+ * [Description]
+ *
+ * Compare the effects of 32-bit div/mod by zero with the "expected"
+ * behaviour.
+ *
+ * The commit "bpf: fix subprog verifier bypass by div/mod by 0
+ * exception", changed div/mod by zero from exiting the current
+ * program to setting the destination register to zero (div) or
+ * leaving it untouched (mod).
+ *
+ * This solved one verfier bug which allowed dodgy pointer values, but
+ * it turned out that the source register was being 32-bit truncated
+ * when it should not be. Also the destination register for mod was
+ * not being truncated when it should be.
+ *
+ * So then we have the following two fixes:
+ * "bpf: Fix 32 bit src register truncation on div/mod"
+ * "bpf: Fix truncation handling for mod32 dst reg wrt zero"
+ *
+ * Testing for all of these issues is a problem. Not least because
+ * division by zero is undefined, so in theory any result is
+ * acceptable so long as the verifier and runtime behaviour
+ * match.
+ *
+ * However to keep things simple we just check if the source and
+ * destination register runtime values match the current upstream
+ * behaviour at the time of writing.
+ *
+ * If the test fails you may have one or more of the above patches
+ * missing. In this case it is possible that you are not vulnerable
+ * depending on what other backports and fixes have been applied. If
+ * upstream changes the behaviour of division by zero, then the test
+ * will need updating.
+ *
+ * Note that we use r6 as the src register and r7 as the dst. w6 and
+ * w7 are the same registers treated as 32bit.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <inttypes.h>
+
+#include "config.h"
+#include "tst_test.h"
+#include "tst_taint.h"
+#include "tst_capability.h"
+#include "lapi/socket.h"
+#include "lapi/bpf.h"
+#include "bpf_common.h"
+
+#define BUFSIZE 8192
+
+static const char MSG[] = "Ahoj!";
+static char *msg;
+
+static int map_fd;
+static uint32_t *key;
+static uint64_t *val;
+static char *log;
+static union bpf_attr *attr;
+
+static int load_prog(void)
+{
+	const struct bpf_insn prog_insn[] = {
+		/* r6 = 1 << 32
+		 * r7 = -1
+		 */
+		BPF_LD_IMM64(BPF_REG_6, 1ULL << 32),
+		BPF_MOV64_IMM(BPF_REG_7, -1LL),
+
+		/* w7 /= w6 */
+		BPF_ALU32_REG(BPF_DIV, BPF_REG_7, BPF_REG_6),
+
+		/* map[1] = r6
+		 * map[2] = r7
+		 */
+		BPF_MAP_ARRAY_STX(map_fd, 0, BPF_REG_6),
+		BPF_MAP_ARRAY_STX(map_fd, 1, BPF_REG_7),
+
+		/* r6 = 1 << 32
+		 * r7 = -1
+		 */
+		BPF_LD_IMM64(BPF_REG_6, 1ULL << 32),
+		BPF_MOV64_IMM(BPF_REG_7, -1LL),
+
+		/* w7 %= w6 */
+		BPF_ALU32_REG(BPF_MOD, BPF_REG_7, BPF_REG_6),
+
+		/* map[3] = r6
+		 * map[4] = r7
+		 */
+		BPF_MAP_ARRAY_STX(map_fd, 2, BPF_REG_6),
+		BPF_MAP_ARRAY_STX(map_fd, 3, BPF_REG_7),
+
+		/* exit(0) */
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN()
+        };
+
+        bpf_init_prog_attr(attr, prog_insn, sizeof(prog_insn), log, BUFSIZE);
+
+	return bpf_load_prog(attr, log);
+}
+
+static void expect_reg_val(const char *const reg_name,
+			   const uint64_t expected_val)
+{
+        bpf_map_array_get(map_fd, key, val);
+        (*key)++;
+
+        if (*val != expected_val) {
+		tst_res(TFAIL,
+			"%s = %"PRIu64", but should be %"PRIu64,
+			reg_name, *val, expected_val);
+	} else {
+		tst_res(TPASS, "%s = %"PRIu64, reg_name, *val);
+	}
+}
+
+static void setup(void)
+{
+	rlimit_bump_memlock();
+	memcpy(msg, MSG, sizeof(MSG));
+}
+
+static void run(void)
+{
+	int prog_fd;
+
+	map_fd = bpf_map_array_create(4);
+	prog_fd = load_prog();
+	bpf_run_prog(prog_fd, msg, sizeof(MSG));
+	SAFE_CLOSE(prog_fd);
+
+	tst_res(TINFO, "Check w7(-1) /= w6(0) [r7 = -1, r6 = 1 << 32]");
+	expect_reg_val("src(r6)", 1UL << 32);
+	expect_reg_val("dst(r7)", 0);
+
+	tst_res(TINFO, "Check w7(-1) %%= w6(0) [r7 = -1, r6 = 1 << 32]");
+	expect_reg_val("src(r6)", 1UL << 32);
+	expect_reg_val("dst(r7)", (uint32_t)-1);
+
+	SAFE_CLOSE(map_fd);
+}
+
+static struct tst_test test = {
+	.setup = setup,
+	.test_all = run,
+	.min_kver = "3.18",
+	.taint_check = TST_TAINT_W | TST_TAINT_D,
+	.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 = BUFSIZE},
+		{&attr, .size = sizeof(*attr)},
+		{&msg, .size = sizeof(MSG)},
+		{}
+	},
+	.tags = (const struct tst_tag[]) {
+		{"linux-git", "f6b1b3bf0d5f"},
+		{"linux-git", "468f6eafa6c4"},
+		{"linux-git", "e88b2c6e5a4d"},
+		{"linux-git", "9b00f1b78809"},
+		{"CVE", "CVE-2021-3444"},
+		{}
+	}
+};
-- 
2.31.1

[LTP] [PATCH v3 4/4] bpf: Check truncation on 32bit div/mod by zero

[Cyril Hrubis]

Hi!
> +	map_fd = bpf_map_array_create(4);
> +	prog_fd = load_prog();
> +	bpf_run_prog(prog_fd, msg, sizeof(MSG));
> +	SAFE_CLOSE(prog_fd);

I've added *key = 0; here so that the test does not break on invalid map
index on subsequent iterations (-i 2).

And also fixed some spaces mixed between tabs used for indentation and
pushed, thanks.

-- 
Cyril Hrubis
chrubis@suse.cz