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32 results

task_fd_query_user.c

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  • task_fd_query_user.c 11.49 KiB
    // SPDX-License-Identifier: GPL-2.0
    
    #include <stdio.h>
    #include <stdlib.h>
    #include <signal.h>
    #include <unistd.h>
    #include <stdbool.h>
    #include <string.h>
    #include <stdint.h>
    #include <fcntl.h>
    #include <linux/bpf.h>
    #include <sys/ioctl.h>
    #include <sys/resource.h>
    #include <sys/types.h>
    #include <sys/stat.h>
    #include <linux/perf_event.h>
    
    #include <bpf/bpf.h>
    #include <bpf/libbpf.h>
    #include "bpf_util.h"
    #include "perf-sys.h"
    #include "trace_helpers.h"
    
    static struct bpf_program *progs[2];
    static struct bpf_link *links[2];
    
    #define CHECK_PERROR_RET(condition) ({			\
    	int __ret = !!(condition);			\
    	if (__ret) {					\
    		printf("FAIL: %s:\n", __func__);	\
    		perror("    ");			\
    		return -1;				\
    	}						\
    })
    
    #define CHECK_AND_RET(condition) ({			\
    	int __ret = !!(condition);			\
    	if (__ret)					\
    		return -1;				\
    })
    
    static __u64 ptr_to_u64(void *ptr)
    {
    	return (__u64) (unsigned long) ptr;
    }
    
    #define PMU_TYPE_FILE "/sys/bus/event_source/devices/%s/type"
    static int bpf_find_probe_type(const char *event_type)
    {
    	char buf[256];
    	int fd, ret;
    
    	ret = snprintf(buf, sizeof(buf), PMU_TYPE_FILE, event_type);
    	CHECK_PERROR_RET(ret < 0 || ret >= sizeof(buf));
    
    	fd = open(buf, O_RDONLY);
    	CHECK_PERROR_RET(fd < 0);
    
    	ret = read(fd, buf, sizeof(buf));
    	close(fd);
    	CHECK_PERROR_RET(ret < 0 || ret >= sizeof(buf));
    
    	errno = 0;
    	ret = (int)strtol(buf, NULL, 10);
    	CHECK_PERROR_RET(errno);
    	return ret;
    }
    
    #define PMU_RETPROBE_FILE "/sys/bus/event_source/devices/%s/format/retprobe"
    static int bpf_get_retprobe_bit(const char *event_type)
    {
    	char buf[256];
    	int fd, ret;
    
    	ret = snprintf(buf, sizeof(buf), PMU_RETPROBE_FILE, event_type);
    	CHECK_PERROR_RET(ret < 0 || ret >= sizeof(buf));
    
    	fd = open(buf, O_RDONLY);
    	CHECK_PERROR_RET(fd < 0);
    
    	ret = read(fd, buf, sizeof(buf));
    	close(fd);
    	CHECK_PERROR_RET(ret < 0 || ret >= sizeof(buf));
    	CHECK_PERROR_RET(strlen(buf) < strlen("config:"));
    
    	errno = 0;
    	ret = (int)strtol(buf + strlen("config:"), NULL, 10);
    	CHECK_PERROR_RET(errno);
    	return ret;
    }
    
    static int test_debug_fs_kprobe(int link_idx, const char *fn_name,
    				__u32 expected_fd_type)
    {
    	__u64 probe_offset, probe_addr;
    	__u32 len, prog_id, fd_type;
    	int err, event_fd;
    	char buf[256];
    
    	len = sizeof(buf);
    	event_fd = bpf_link__fd(links[link_idx]);
    	err = bpf_task_fd_query(getpid(), event_fd, 0, buf, &len,
    				&prog_id, &fd_type, &probe_offset,
    				&probe_addr);
    	if (err < 0) {
    		printf("FAIL: %s, for event_fd idx %d, fn_name %s\n",
    		       __func__, link_idx, fn_name);
    		perror("    :");
    		return -1;
    	}
    	if (strcmp(buf, fn_name) != 0 ||
    	    fd_type != expected_fd_type ||
    	    probe_offset != 0x0 || probe_addr != 0x0) {
    		printf("FAIL: bpf_trace_event_query(event_fd[%d]):\n",
    		       link_idx);
    		printf("buf: %s, fd_type: %u, probe_offset: 0x%llx,"
    		       " probe_addr: 0x%llx\n",
    		       buf, fd_type, probe_offset, probe_addr);
    		return -1;
    	}
    	return 0;
    }
    
    static int test_nondebug_fs_kuprobe_common(const char *event_type,
    	const char *name, __u64 offset, __u64 addr, bool is_return,
    	char *buf, __u32 *buf_len, __u32 *prog_id, __u32 *fd_type,
    	__u64 *probe_offset, __u64 *probe_addr)
    {
    	int is_return_bit = bpf_get_retprobe_bit(event_type);
    	int type = bpf_find_probe_type(event_type);
    	struct perf_event_attr attr = {};
    	struct bpf_link *link;
    	int fd, err = -1;
    
    	if (type < 0 || is_return_bit < 0) {
    		printf("FAIL: %s incorrect type (%d) or is_return_bit (%d)\n",
    			__func__, type, is_return_bit);
    		return err;
    	}
    
    	attr.sample_period = 1;
    	attr.wakeup_events = 1;
    	if (is_return)
    		attr.config |= 1 << is_return_bit;
    
    	if (name) {
    		attr.config1 = ptr_to_u64((void *)name);
    		attr.config2 = offset;
    	} else {
    		attr.config1 = 0;
    		attr.config2 = addr;
    	}
    	attr.size = sizeof(attr);
    	attr.type = type;
    
    	fd = sys_perf_event_open(&attr, -1, 0, -1, 0);
    	link = bpf_program__attach_perf_event(progs[0], fd);
    	if (libbpf_get_error(link)) {
    		printf("ERROR: bpf_program__attach_perf_event failed\n");
    		link = NULL;
    		close(fd);
    		goto cleanup;
    	}
    
    	CHECK_PERROR_RET(bpf_task_fd_query(getpid(), fd, 0, buf, buf_len,
    			 prog_id, fd_type, probe_offset, probe_addr) < 0);
    	err = 0;
    
    cleanup:
    	bpf_link__destroy(link);
    	return err;
    }
    
    static int test_nondebug_fs_probe(const char *event_type, const char *name,
    				  __u64 offset, __u64 addr, bool is_return,
    				  __u32 expected_fd_type,
    				  __u32 expected_ret_fd_type,
    				  char *buf, __u32 buf_len)
    {
    	__u64 probe_offset, probe_addr;
    	__u32 prog_id, fd_type;
    	int err;
    
    	err = test_nondebug_fs_kuprobe_common(event_type, name,
    					      offset, addr, is_return,
    					      buf, &buf_len, &prog_id,
    					      &fd_type, &probe_offset,
    					      &probe_addr);
    	if (err < 0) {
    		printf("FAIL: %s, "
    		       "for name %s, offset 0x%llx, addr 0x%llx, is_return %d\n",
    		       __func__, name ? name : "", offset, addr, is_return);
    		perror("    :");
    		return -1;
    	}
    	if ((is_return && fd_type != expected_ret_fd_type) ||
    	    (!is_return && fd_type != expected_fd_type)) {
    		printf("FAIL: %s, incorrect fd_type %u\n",
    		       __func__, fd_type);
    		return -1;
    	}
    	if (name) {
    		if (strcmp(name, buf) != 0) {
    			printf("FAIL: %s, incorrect buf %s\n", __func__, buf);
    			return -1;
    		}
    		if (probe_offset != offset) {
    			printf("FAIL: %s, incorrect probe_offset 0x%llx\n",
    			       __func__, probe_offset);
    			return -1;
    		}
    	} else {
    		if (buf_len != 0) {
    			printf("FAIL: %s, incorrect buf %p\n",
    			       __func__, buf);
    			return -1;
    		}
    
    		if (probe_addr != addr) {
    			printf("FAIL: %s, incorrect probe_addr 0x%llx\n",
    			       __func__, probe_addr);
    			return -1;
    		}
    	}
    	return 0;
    }
    
    static int test_debug_fs_uprobe(char *binary_path, long offset, bool is_return)
    {
    	char buf[256], event_alias[sizeof("test_1234567890")];
    	const char *event_type = "uprobe";
    	struct perf_event_attr attr = {};
    	__u64 probe_offset, probe_addr;
    	__u32 len, prog_id, fd_type;
    	int err = -1, res, kfd, efd;
    	struct bpf_link *link;
    	ssize_t bytes;
    
    	snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/%s_events",
    		 event_type);
    	kfd = open(buf, O_WRONLY | O_TRUNC, 0);
    	CHECK_PERROR_RET(kfd < 0);
    
    	res = snprintf(event_alias, sizeof(event_alias), "test_%d", getpid());
    	CHECK_PERROR_RET(res < 0 || res >= sizeof(event_alias));
    
    	res = snprintf(buf, sizeof(buf), "%c:%ss/%s %s:0x%lx",
    		       is_return ? 'r' : 'p', event_type, event_alias,
    		       binary_path, offset);
    	CHECK_PERROR_RET(res < 0 || res >= sizeof(buf));
    	CHECK_PERROR_RET(write(kfd, buf, strlen(buf)) < 0);
    
    	close(kfd);
    	kfd = -1;
    
    	snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%ss/%s/id",
    		 event_type, event_alias);
    	efd = open(buf, O_RDONLY, 0);
    	CHECK_PERROR_RET(efd < 0);
    
    	bytes = read(efd, buf, sizeof(buf));
    	CHECK_PERROR_RET(bytes <= 0 || bytes >= sizeof(buf));
    	close(efd);
    	buf[bytes] = '\0';
    
    	attr.config = strtol(buf, NULL, 0);
    	attr.type = PERF_TYPE_TRACEPOINT;
    	attr.sample_period = 1;
    	attr.wakeup_events = 1;
    
    	kfd = sys_perf_event_open(&attr, -1, 0, -1, PERF_FLAG_FD_CLOEXEC);
    	link = bpf_program__attach_perf_event(progs[0], kfd);
    	if (libbpf_get_error(link)) {
    		printf("ERROR: bpf_program__attach_perf_event failed\n");
    		link = NULL;
    		close(kfd);
    		goto cleanup;
    	}
    
    	len = sizeof(buf);
    	err = bpf_task_fd_query(getpid(), kfd, 0, buf, &len,
    				&prog_id, &fd_type, &probe_offset,
    				&probe_addr);
    	if (err < 0) {
    		printf("FAIL: %s, binary_path %s\n", __func__, binary_path);
    		perror("    :");
    		return -1;
    	}
    	if ((is_return && fd_type != BPF_FD_TYPE_URETPROBE) ||
    	    (!is_return && fd_type != BPF_FD_TYPE_UPROBE)) {
    		printf("FAIL: %s, incorrect fd_type %u\n", __func__,
    		       fd_type);
    		return -1;
    	}
    	if (strcmp(binary_path, buf) != 0) {
    		printf("FAIL: %s, incorrect buf %s\n", __func__, buf);
    		return -1;
    	}
    	if (probe_offset != offset) {
    		printf("FAIL: %s, incorrect probe_offset 0x%llx\n", __func__,
    		       probe_offset);
    		return -1;
    	}
    	err = 0;
    
    cleanup:
    	bpf_link__destroy(link);
    	return err;
    }
    
    int main(int argc, char **argv)
    {
    	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
    	extern char __executable_start;
    	char filename[256], buf[256];
    	__u64 uprobe_file_offset;
    	struct bpf_program *prog;
    	struct bpf_object *obj;
    	int i = 0, err = -1;
    
    	if (setrlimit(RLIMIT_MEMLOCK, &r)) {
    		perror("setrlimit(RLIMIT_MEMLOCK)");
    		return err;
    	}
    
    	if (load_kallsyms()) {
    		printf("failed to process /proc/kallsyms\n");
    		return err;
    	}
    
    	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
    	obj = bpf_object__open_file(filename, NULL);
    	if (libbpf_get_error(obj)) {
    		fprintf(stderr, "ERROR: opening BPF object file failed\n");
    		return err;
    	}
    
    	/* load BPF program */
    	if (bpf_object__load(obj)) {
    		fprintf(stderr, "ERROR: loading BPF object file failed\n");
    		goto cleanup;
    	}
    
    	bpf_object__for_each_program(prog, obj) {
    		progs[i] = prog;
    		links[i] = bpf_program__attach(progs[i]);
    		if (libbpf_get_error(links[i])) {
    			fprintf(stderr, "ERROR: bpf_program__attach failed\n");
    			links[i] = NULL;
    			goto cleanup;
    		}
    		i++;
    	}
    
    	/* test two functions in the corresponding *_kern.c file */
    	CHECK_AND_RET(test_debug_fs_kprobe(0, "blk_mq_start_request",
    					   BPF_FD_TYPE_KPROBE));
    	CHECK_AND_RET(test_debug_fs_kprobe(1, "blk_account_io_done",
    					   BPF_FD_TYPE_KRETPROBE));
    
    	/* test nondebug fs kprobe */
    	CHECK_AND_RET(test_nondebug_fs_probe("kprobe", "bpf_check", 0x0, 0x0,
    					     false, BPF_FD_TYPE_KPROBE,
    					     BPF_FD_TYPE_KRETPROBE,
    					     buf, sizeof(buf)));
    #ifdef __x86_64__
    	/* set a kprobe on "bpf_check + 0x5", which is x64 specific */
    	CHECK_AND_RET(test_nondebug_fs_probe("kprobe", "bpf_check", 0x5, 0x0,
    					     false, BPF_FD_TYPE_KPROBE,
    					     BPF_FD_TYPE_KRETPROBE,
    					     buf, sizeof(buf)));
    #endif
    	CHECK_AND_RET(test_nondebug_fs_probe("kprobe", "bpf_check", 0x0, 0x0,
    					     true, BPF_FD_TYPE_KPROBE,
    					     BPF_FD_TYPE_KRETPROBE,
    					     buf, sizeof(buf)));
    	CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
    					     ksym_get_addr("bpf_check"), false,
    					     BPF_FD_TYPE_KPROBE,
    					     BPF_FD_TYPE_KRETPROBE,
    					     buf, sizeof(buf)));
    	CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
    					     ksym_get_addr("bpf_check"), false,
    					     BPF_FD_TYPE_KPROBE,
    					     BPF_FD_TYPE_KRETPROBE,
    					     NULL, 0));
    	CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
    					     ksym_get_addr("bpf_check"), true,
    					     BPF_FD_TYPE_KPROBE,
    					     BPF_FD_TYPE_KRETPROBE,
    					     buf, sizeof(buf)));
    	CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
    					     ksym_get_addr("bpf_check"), true,
    					     BPF_FD_TYPE_KPROBE,
    					     BPF_FD_TYPE_KRETPROBE,
    					     0, 0));
    
    	/* test nondebug fs uprobe */
    	/* the calculation of uprobe file offset is based on gcc 7.3.1 on x64
    	 * and the default linker script, which defines __executable_start as
    	 * the start of the .text section. The calculation could be different
    	 * on different systems with different compilers. The right way is
    	 * to parse the ELF file. We took a shortcut here.
    	 */
    	uprobe_file_offset = (__u64)main - (__u64)&__executable_start;
    	CHECK_AND_RET(test_nondebug_fs_probe("uprobe", (char *)argv[0],
    					     uprobe_file_offset, 0x0, false,
    					     BPF_FD_TYPE_UPROBE,
    					     BPF_FD_TYPE_URETPROBE,
    					     buf, sizeof(buf)));
    	CHECK_AND_RET(test_nondebug_fs_probe("uprobe", (char *)argv[0],
    					     uprobe_file_offset, 0x0, true,
    					     BPF_FD_TYPE_UPROBE,
    					     BPF_FD_TYPE_URETPROBE,
    					     buf, sizeof(buf)));
    
    	/* test debug fs uprobe */
    	CHECK_AND_RET(test_debug_fs_uprobe((char *)argv[0], uprobe_file_offset,
    					   false));
    	CHECK_AND_RET(test_debug_fs_uprobe((char *)argv[0], uprobe_file_offset,
    					   true));
    	err = 0;
    
    cleanup:
    	for (i--; i >= 0; i--)
    		bpf_link__destroy(links[i]);
    
    	bpf_object__close(obj);
    	return err;
    }