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Commit 965de87e authored by Josef Bacik's avatar Josef Bacik Committed by Alexei Starovoitov
Browse files

samples/bpf: add a test for bpf_override_return 



This adds a basic test for bpf_override_return to verify it works.  We
override the main function for mounting a btrfs fs so it'll return
-ENOMEM and then make sure that trying to mount a btrfs fs will fail.

Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 9802d865

samples/bpf/Makefile

+4 −0
Original line number Original line Diff line number Diff line
@@ -12,6 +12,7 @@ hostprogs-y += tracex3 
hostprogs-y += tracex4

hostprogs-y += tracex4

hostprogs-y += tracex5

hostprogs-y += tracex5

hostprogs-y += tracex6

hostprogs-y += tracex6

hostprogs-y += tracex7

hostprogs-y += test_probe_write_user

hostprogs-y += test_probe_write_user

hostprogs-y += trace_output

hostprogs-y += trace_output

hostprogs-y += lathist

hostprogs-y += lathist
@@ -58,6 +59,7 @@ tracex3-objs := bpf_load.o $(LIBBPF) tracex3_user.o 
tracex4-objs := bpf_load.o $(LIBBPF) tracex4_user.o

tracex4-objs := bpf_load.o $(LIBBPF) tracex4_user.o

tracex5-objs := bpf_load.o $(LIBBPF) tracex5_user.o

tracex5-objs := bpf_load.o $(LIBBPF) tracex5_user.o

tracex6-objs := bpf_load.o $(LIBBPF) tracex6_user.o

tracex6-objs := bpf_load.o $(LIBBPF) tracex6_user.o

tracex7-objs := bpf_load.o $(LIBBPF) tracex7_user.o

load_sock_ops-objs := bpf_load.o $(LIBBPF) load_sock_ops.o

load_sock_ops-objs := bpf_load.o $(LIBBPF) load_sock_ops.o

test_probe_write_user-objs := bpf_load.o $(LIBBPF) test_probe_write_user_user.o

test_probe_write_user-objs := bpf_load.o $(LIBBPF) test_probe_write_user_user.o

trace_output-objs := bpf_load.o $(LIBBPF) trace_output_user.o

trace_output-objs := bpf_load.o $(LIBBPF) trace_output_user.o
@@ -101,6 +103,7 @@ always += tracex3_kern.o 
always += tracex4_kern.o

always += tracex4_kern.o

always += tracex5_kern.o

always += tracex5_kern.o

always += tracex6_kern.o

always += tracex6_kern.o

always += tracex7_kern.o

always += sock_flags_kern.o

always += sock_flags_kern.o

always += test_probe_write_user_kern.o

always += test_probe_write_user_kern.o

always += trace_output_kern.o

always += trace_output_kern.o
@@ -155,6 +158,7 @@ HOSTLOADLIBES_tracex3 += -lelf 
HOSTLOADLIBES_tracex4 += -lelf -lrt

HOSTLOADLIBES_tracex4 += -lelf -lrt

HOSTLOADLIBES_tracex5 += -lelf

HOSTLOADLIBES_tracex5 += -lelf

HOSTLOADLIBES_tracex6 += -lelf

HOSTLOADLIBES_tracex6 += -lelf

HOSTLOADLIBES_tracex7 += -lelf

HOSTLOADLIBES_test_cgrp2_sock2 += -lelf

HOSTLOADLIBES_test_cgrp2_sock2 += -lelf

HOSTLOADLIBES_load_sock_ops += -lelf

HOSTLOADLIBES_load_sock_ops += -lelf

HOSTLOADLIBES_test_probe_write_user += -lelf

HOSTLOADLIBES_test_probe_write_user += -lelf

samples/bpf/test_override_return.sh

0 → 100755
+15 −0
Original line number Original line Diff line number Diff line 
#!/bin/bash



rm -f testfile.img

dd if=/dev/zero of=testfile.img bs=1M seek=1000 count=1

DEVICE=$(losetup --show -f testfile.img)

mkfs.btrfs -f $DEVICE

mkdir tmpmnt

./tracex7 $DEVICE

if [ $? -eq 0 ]

then

	echo "SUCCESS!"

else

	echo "FAILED!"

fi

losetup -d $DEVICE

samples/bpf/tracex7_kern.c

0 → 100644
+16 −0
Original line number Original line Diff line number Diff line 
#include <uapi/linux/ptrace.h>

#include <uapi/linux/bpf.h>

#include <linux/version.h>

#include "bpf_helpers.h"



SEC("kprobe/open_ctree")

int bpf_prog1(struct pt_regs *ctx)

{

	unsigned long rc = -12;



	bpf_override_return(ctx, rc);

	return 0;

}



char _license[] SEC("license") = "GPL";

u32 _version SEC("version") = LINUX_VERSION_CODE;

samples/bpf/tracex7_user.c

0 → 100644
+28 −0
Original line number Original line Diff line number Diff line 
#define _GNU_SOURCE



#include <stdio.h>

#include <linux/bpf.h>

#include <unistd.h>

#include "libbpf.h"

#include "bpf_load.h"



int main(int argc, char **argv)

{

	FILE *f;

	char filename[256];

	char command[256];

	int ret;



	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);



	if (load_bpf_file(filename)) {

		printf("%s", bpf_log_buf);

		return 1;

	}



	snprintf(command, 256, "mount %s tmpmnt/", argv[1]);

	f = popen(command, "r");

	ret = pclose(f);



	return ret ? 0 : 1;

}

tools/include/uapi/linux/bpf.h

+6 −1
Original line number Original line Diff line number Diff line
@@ -677,6 +677,10 @@ union bpf_attr { 
 *     @buf: buf to fill

 *     @buf: buf to fill

 *     @buf_size: size of the buf

 *     @buf_size: size of the buf

 *     Return : 0 on success or negative error code

 *     Return : 0 on success or negative error code

 *

 * int bpf_override_return(pt_regs, rc)

 *	@pt_regs: pointer to struct pt_regs

 *	@rc: the return value to set

 */

 */

#define __BPF_FUNC_MAPPER(FN)		\

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\

	FN(unspec),			\
@@ -736,7 +740,8 @@ union bpf_attr { 
	FN(xdp_adjust_meta),		\

	FN(xdp_adjust_meta),		\

	FN(perf_event_read_value),	\

	FN(perf_event_read_value),	\

	FN(perf_prog_read_value),	\

	FN(perf_prog_read_value),	\

	FN(getsockopt),

	FN(getsockopt),			\

	FN(override_return),





/* integer value in 'imm' field of BPF_CALL instruction selects which helper

/* integer value in 'imm' field of BPF_CALL instruction selects which helper

 * function eBPF program intends to call

 * function eBPF program intends to call