Initial import

1 files changed, 312 insertions, 0 deletions

diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c
new file mode 100644
index 000000000..38dac5a53
--- /dev/null
+++ b/samples/bpf/bpf_load.c
@@ -0,0 +1,312 @@
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <libelf.h>
+#include <gelf.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <linux/bpf.h>
+#include <linux/filter.h>
+#include <linux/perf_event.h>
+#include <sys/syscall.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <poll.h>
+#include "libbpf.h"
+#include "bpf_helpers.h"
+#include "bpf_load.h"
+
+#define DEBUGFS "/sys/kernel/debug/tracing/"
+
+static char license[128];
+static int kern_version;
+static bool processed_sec[128];
+int map_fd[MAX_MAPS];
+int prog_fd[MAX_PROGS];
+int event_fd[MAX_PROGS];
+int prog_cnt;
+
+static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
+{
+	bool is_socket = strncmp(event, "socket", 6) == 0;
+	bool is_kprobe = strncmp(event, "kprobe/", 7) == 0;
+	bool is_kretprobe = strncmp(event, "kretprobe/", 10) == 0;
+	enum bpf_prog_type prog_type;
+	char buf[256];
+	int fd, efd, err, id;
+	struct perf_event_attr attr = {};
+
+	attr.type = PERF_TYPE_TRACEPOINT;
+	attr.sample_type = PERF_SAMPLE_RAW;
+	attr.sample_period = 1;
+	attr.wakeup_events = 1;
+
+	if (is_socket) {
+		prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+	} else if (is_kprobe || is_kretprobe) {
+		prog_type = BPF_PROG_TYPE_KPROBE;
+	} else {
+		printf("Unknown event '%s'\n", event);
+		return -1;
+	}
+
+	if (is_kprobe || is_kretprobe) {
+		if (is_kprobe)
+			event += 7;
+		else
+			event += 10;
+
+		snprintf(buf, sizeof(buf),
+			 "echo '%c:%s %s' >> /sys/kernel/debug/tracing/kprobe_events",
+			 is_kprobe ? 'p' : 'r', event, event);
+		err = system(buf);
+		if (err < 0) {
+			printf("failed to create kprobe '%s' error '%s'\n",
+			       event, strerror(errno));
+			return -1;
+		}
+	}
+
+	fd = bpf_prog_load(prog_type, prog, size, license, kern_version);
+
+	if (fd < 0) {
+		printf("bpf_prog_load() err=%d\n%s", errno, bpf_log_buf);
+		return -1;
+	}
+
+	prog_fd[prog_cnt++] = fd;
+
+	if (is_socket)
+		return 0;
+
+	strcpy(buf, DEBUGFS);
+	strcat(buf, "events/kprobes/");
+	strcat(buf, event);
+	strcat(buf, "/id");
+
+	efd = open(buf, O_RDONLY, 0);
+	if (efd < 0) {
+		printf("failed to open event %s\n", event);
+		return -1;
+	}
+
+	err = read(efd, buf, sizeof(buf));
+	if (err < 0 || err >= sizeof(buf)) {
+		printf("read from '%s' failed '%s'\n", event, strerror(errno));
+		return -1;
+	}
+
+	close(efd);
+
+	buf[err] = 0;
+	id = atoi(buf);
+	attr.config = id;
+
+	efd = perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0);
+	if (efd < 0) {
+		printf("event %d fd %d err %s\n", id, efd, strerror(errno));
+		return -1;
+	}
+	event_fd[prog_cnt - 1] = efd;
+	ioctl(efd, PERF_EVENT_IOC_ENABLE, 0);
+	ioctl(efd, PERF_EVENT_IOC_SET_BPF, fd);
+
+	return 0;
+}
+
+static int load_maps(struct bpf_map_def *maps, int len)
+{
+	int i;
+
+	for (i = 0; i < len / sizeof(struct bpf_map_def); i++) {
+
+		map_fd[i] = bpf_create_map(maps[i].type,
+					   maps[i].key_size,
+					   maps[i].value_size,
+					   maps[i].max_entries);
+		if (map_fd[i] < 0)
+			return 1;
+	}
+	return 0;
+}
+
+static int get_sec(Elf *elf, int i, GElf_Ehdr *ehdr, char **shname,
+		   GElf_Shdr *shdr, Elf_Data **data)
+{
+	Elf_Scn *scn;
+
+	scn = elf_getscn(elf, i);
+	if (!scn)
+		return 1;
+
+	if (gelf_getshdr(scn, shdr) != shdr)
+		return 2;
+
+	*shname = elf_strptr(elf, ehdr->e_shstrndx, shdr->sh_name);
+	if (!*shname || !shdr->sh_size)
+		return 3;
+
+	*data = elf_getdata(scn, 0);
+	if (!*data || elf_getdata(scn, *data) != NULL)
+		return 4;
+
+	return 0;
+}
+
+static int parse_relo_and_apply(Elf_Data *data, Elf_Data *symbols,
+				GElf_Shdr *shdr, struct bpf_insn *insn)
+{
+	int i, nrels;
+
+	nrels = shdr->sh_size / shdr->sh_entsize;
+
+	for (i = 0; i < nrels; i++) {
+		GElf_Sym sym;
+		GElf_Rel rel;
+		unsigned int insn_idx;
+
+		gelf_getrel(data, i, &rel);
+
+		insn_idx = rel.r_offset / sizeof(struct bpf_insn);
+
+		gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym);
+
+		if (insn[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) {
+			printf("invalid relo for insn[%d].code 0x%x\n",
+			       insn_idx, insn[insn_idx].code);
+			return 1;
+		}
+		insn[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
+		insn[insn_idx].imm = map_fd[sym.st_value / sizeof(struct bpf_map_def)];
+	}
+
+	return 0;
+}
+
+int load_bpf_file(char *path)
+{
+	int fd, i;
+	Elf *elf;
+	GElf_Ehdr ehdr;
+	GElf_Shdr shdr, shdr_prog;
+	Elf_Data *data, *data_prog, *symbols = NULL;
+	char *shname, *shname_prog;
+
+	if (elf_version(EV_CURRENT) == EV_NONE)
+		return 1;
+
+	fd = open(path, O_RDONLY, 0);
+	if (fd < 0)
+		return 1;
+
+	elf = elf_begin(fd, ELF_C_READ, NULL);
+
+	if (!elf)
+		return 1;
+
+	if (gelf_getehdr(elf, &ehdr) != &ehdr)
+		return 1;
+
+	/* clear all kprobes */
+	i = system("echo \"\" > /sys/kernel/debug/tracing/kprobe_events");
+
+	/* scan over all elf sections to get license and map info */
+	for (i = 1; i < ehdr.e_shnum; i++) {
+
+		if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
+			continue;
+
+		if (0) /* helpful for llvm debugging */
+			printf("section %d:%s data %p size %zd link %d flags %d\n",
+			       i, shname, data->d_buf, data->d_size,
+			       shdr.sh_link, (int) shdr.sh_flags);
+
+		if (strcmp(shname, "license") == 0) {
+			processed_sec[i] = true;
+			memcpy(license, data->d_buf, data->d_size);
+		} else if (strcmp(shname, "version") == 0) {
+			processed_sec[i] = true;
+			if (data->d_size != sizeof(int)) {
+				printf("invalid size of version section %zd\n",
+				       data->d_size);
+				return 1;
+			}
+			memcpy(&kern_version, data->d_buf, sizeof(int));
+		} else if (strcmp(shname, "maps") == 0) {
+			processed_sec[i] = true;
+			if (load_maps(data->d_buf, data->d_size))
+				return 1;
+		} else if (shdr.sh_type == SHT_SYMTAB) {
+			symbols = data;
+		}
+	}
+
+	/* load programs that need map fixup (relocations) */
+	for (i = 1; i < ehdr.e_shnum; i++) {
+
+		if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
+			continue;
+		if (shdr.sh_type == SHT_REL) {
+			struct bpf_insn *insns;
+
+			if (get_sec(elf, shdr.sh_info, &ehdr, &shname_prog,
+				    &shdr_prog, &data_prog))
+				continue;
+
+			insns = (struct bpf_insn *) data_prog->d_buf;
+
+			processed_sec[shdr.sh_info] = true;
+			processed_sec[i] = true;
+
+			if (parse_relo_and_apply(data, symbols, &shdr, insns))
+				continue;
+
+			if (memcmp(shname_prog, "kprobe/", 7) == 0 ||
+			    memcmp(shname_prog, "kretprobe/", 10) == 0 ||
+			    memcmp(shname_prog, "socket", 6) == 0)
+				load_and_attach(shname_prog, insns, data_prog->d_size);
+		}
+	}
+
+	/* load programs that don't use maps */
+	for (i = 1; i < ehdr.e_shnum; i++) {
+
+		if (processed_sec[i])
+			continue;
+
+		if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
+			continue;
+
+		if (memcmp(shname, "kprobe/", 7) == 0 ||
+		    memcmp(shname, "kretprobe/", 10) == 0 ||
+		    memcmp(shname, "socket", 6) == 0)
+			load_and_attach(shname, data->d_buf, data->d_size);
+	}
+
+	close(fd);
+	return 0;
+}
+
+void read_trace_pipe(void)
+{
+	int trace_fd;
+
+	trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
+	if (trace_fd < 0)
+		return;
+
+	while (1) {
+		static char buf[4096];
+		ssize_t sz;
+
+		sz = read(trace_fd, buf, sizeof(buf));
+		if (sz > 0) {
+			buf[sz] = 0;
+			puts(buf);
+		}
+	}
+}