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-rw-r--r--samples/bpf/bpf_load.c667
1 files changed, 667 insertions, 0 deletions
diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c
new file mode 100644
index 000000000..c5ad528f0
--- /dev/null
+++ b/samples/bpf/bpf_load.c
@@ -0,0 +1,667 @@
+// SPDX-License-Identifier: GPL-2.0
+#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 <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <linux/types.h>
+#include <sys/socket.h>
+#include <sys/syscall.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <poll.h>
+#include <ctype.h>
+#include <assert.h>
+#include <bpf/bpf.h>
+#include "bpf_load.h"
+#include "perf-sys.h"
+
+#define DEBUGFS "/sys/kernel/debug/tracing/"
+
+static char license[128];
+static int kern_version;
+static bool processed_sec[128];
+char bpf_log_buf[BPF_LOG_BUF_SIZE];
+int map_fd[MAX_MAPS];
+int prog_fd[MAX_PROGS];
+int event_fd[MAX_PROGS];
+int prog_cnt;
+int prog_array_fd = -1;
+
+struct bpf_map_data map_data[MAX_MAPS];
+int map_data_count;
+
+static int populate_prog_array(const char *event, int prog_fd)
+{
+ int ind = atoi(event), err;
+
+ err = bpf_map_update_elem(prog_array_fd, &ind, &prog_fd, BPF_ANY);
+ if (err < 0) {
+ printf("failed to store prog_fd in prog_array\n");
+ return -1;
+ }
+ return 0;
+}
+
+static int write_kprobe_events(const char *val)
+{
+ int fd, ret, flags;
+
+ if (val == NULL)
+ return -1;
+ else if (val[0] == '\0')
+ flags = O_WRONLY | O_TRUNC;
+ else
+ flags = O_WRONLY | O_APPEND;
+
+ fd = open(DEBUGFS "kprobe_events", flags);
+
+ ret = write(fd, val, strlen(val));
+ close(fd);
+
+ return ret;
+}
+
+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;
+ bool is_tracepoint = strncmp(event, "tracepoint/", 11) == 0;
+ bool is_raw_tracepoint = strncmp(event, "raw_tracepoint/", 15) == 0;
+ bool is_xdp = strncmp(event, "xdp", 3) == 0;
+ bool is_perf_event = strncmp(event, "perf_event", 10) == 0;
+ bool is_cgroup_skb = strncmp(event, "cgroup/skb", 10) == 0;
+ bool is_cgroup_sk = strncmp(event, "cgroup/sock", 11) == 0;
+ bool is_sockops = strncmp(event, "sockops", 7) == 0;
+ bool is_sk_skb = strncmp(event, "sk_skb", 6) == 0;
+ bool is_sk_msg = strncmp(event, "sk_msg", 6) == 0;
+ size_t insns_cnt = size / sizeof(struct bpf_insn);
+ 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 if (is_tracepoint) {
+ prog_type = BPF_PROG_TYPE_TRACEPOINT;
+ } else if (is_raw_tracepoint) {
+ prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT;
+ } else if (is_xdp) {
+ prog_type = BPF_PROG_TYPE_XDP;
+ } else if (is_perf_event) {
+ prog_type = BPF_PROG_TYPE_PERF_EVENT;
+ } else if (is_cgroup_skb) {
+ prog_type = BPF_PROG_TYPE_CGROUP_SKB;
+ } else if (is_cgroup_sk) {
+ prog_type = BPF_PROG_TYPE_CGROUP_SOCK;
+ } else if (is_sockops) {
+ prog_type = BPF_PROG_TYPE_SOCK_OPS;
+ } else if (is_sk_skb) {
+ prog_type = BPF_PROG_TYPE_SK_SKB;
+ } else if (is_sk_msg) {
+ prog_type = BPF_PROG_TYPE_SK_MSG;
+ } else {
+ printf("Unknown event '%s'\n", event);
+ return -1;
+ }
+
+ if (prog_cnt == MAX_PROGS)
+ return -1;
+
+ fd = bpf_load_program(prog_type, prog, insns_cnt, license, kern_version,
+ bpf_log_buf, BPF_LOG_BUF_SIZE);
+ if (fd < 0) {
+ printf("bpf_load_program() err=%d\n%s", errno, bpf_log_buf);
+ return -1;
+ }
+
+ prog_fd[prog_cnt++] = fd;
+
+ if (is_xdp || is_perf_event || is_cgroup_skb || is_cgroup_sk)
+ return 0;
+
+ if (is_socket || is_sockops || is_sk_skb || is_sk_msg) {
+ if (is_socket)
+ event += 6;
+ else
+ event += 7;
+ if (*event != '/')
+ return 0;
+ event++;
+ if (!isdigit(*event)) {
+ printf("invalid prog number\n");
+ return -1;
+ }
+ return populate_prog_array(event, fd);
+ }
+
+ if (is_raw_tracepoint) {
+ efd = bpf_raw_tracepoint_open(event + 15, fd);
+ if (efd < 0) {
+ printf("tracepoint %s %s\n", event + 15, strerror(errno));
+ return -1;
+ }
+ event_fd[prog_cnt - 1] = efd;
+ return 0;
+ }
+
+ if (is_kprobe || is_kretprobe) {
+ bool need_normal_check = true;
+ const char *event_prefix = "";
+
+ if (is_kprobe)
+ event += 7;
+ else
+ event += 10;
+
+ if (*event == 0) {
+ printf("event name cannot be empty\n");
+ return -1;
+ }
+
+ if (isdigit(*event))
+ return populate_prog_array(event, fd);
+
+#ifdef __x86_64__
+ if (strncmp(event, "sys_", 4) == 0) {
+ snprintf(buf, sizeof(buf), "%c:__x64_%s __x64_%s",
+ is_kprobe ? 'p' : 'r', event, event);
+ err = write_kprobe_events(buf);
+ if (err >= 0) {
+ need_normal_check = false;
+ event_prefix = "__x64_";
+ }
+ }
+#endif
+ if (need_normal_check) {
+ snprintf(buf, sizeof(buf), "%c:%s %s",
+ is_kprobe ? 'p' : 'r', event, event);
+ err = write_kprobe_events(buf);
+ if (err < 0) {
+ printf("failed to create kprobe '%s' error '%s'\n",
+ event, strerror(errno));
+ return -1;
+ }
+ }
+
+ strcpy(buf, DEBUGFS);
+ strcat(buf, "events/kprobes/");
+ strcat(buf, event_prefix);
+ strcat(buf, event);
+ strcat(buf, "/id");
+ } else if (is_tracepoint) {
+ event += 11;
+
+ if (*event == 0) {
+ printf("event name cannot be empty\n");
+ return -1;
+ }
+ strcpy(buf, DEBUGFS);
+ strcat(buf, "events/");
+ 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 = sys_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;
+ err = ioctl(efd, PERF_EVENT_IOC_ENABLE, 0);
+ if (err < 0) {
+ printf("ioctl PERF_EVENT_IOC_ENABLE failed err %s\n",
+ strerror(errno));
+ return -1;
+ }
+ err = ioctl(efd, PERF_EVENT_IOC_SET_BPF, fd);
+ if (err < 0) {
+ printf("ioctl PERF_EVENT_IOC_SET_BPF failed err %s\n",
+ strerror(errno));
+ return -1;
+ }
+
+ return 0;
+}
+
+static int load_maps(struct bpf_map_data *maps, int nr_maps,
+ fixup_map_cb fixup_map)
+{
+ int i, numa_node;
+
+ for (i = 0; i < nr_maps; i++) {
+ if (fixup_map) {
+ fixup_map(&maps[i], i);
+ /* Allow userspace to assign map FD prior to creation */
+ if (maps[i].fd != -1) {
+ map_fd[i] = maps[i].fd;
+ continue;
+ }
+ }
+
+ numa_node = maps[i].def.map_flags & BPF_F_NUMA_NODE ?
+ maps[i].def.numa_node : -1;
+
+ if (maps[i].def.type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
+ maps[i].def.type == BPF_MAP_TYPE_HASH_OF_MAPS) {
+ int inner_map_fd = map_fd[maps[i].def.inner_map_idx];
+
+ map_fd[i] = bpf_create_map_in_map_node(maps[i].def.type,
+ maps[i].name,
+ maps[i].def.key_size,
+ inner_map_fd,
+ maps[i].def.max_entries,
+ maps[i].def.map_flags,
+ numa_node);
+ } else {
+ map_fd[i] = bpf_create_map_node(maps[i].def.type,
+ maps[i].name,
+ maps[i].def.key_size,
+ maps[i].def.value_size,
+ maps[i].def.max_entries,
+ maps[i].def.map_flags,
+ numa_node);
+ }
+ if (map_fd[i] < 0) {
+ printf("failed to create map %d (%s): %d %s\n",
+ i, maps[i].name, errno, strerror(errno));
+ return 1;
+ }
+ maps[i].fd = map_fd[i];
+
+ if (maps[i].def.type == BPF_MAP_TYPE_PROG_ARRAY)
+ prog_array_fd = map_fd[i];
+ }
+ 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,
+ struct bpf_map_data *maps, int nr_maps)
+{
+ 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;
+ bool match = false;
+ int j, map_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;
+
+ /* Match FD relocation against recorded map_data[] offset */
+ for (map_idx = 0; map_idx < nr_maps; map_idx++) {
+ if (maps[map_idx].elf_offset == sym.st_value) {
+ match = true;
+ break;
+ }
+ }
+ if (match) {
+ insn[insn_idx].imm = maps[map_idx].fd;
+ } else {
+ printf("invalid relo for insn[%d] no map_data match\n",
+ insn_idx);
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+static int cmp_symbols(const void *l, const void *r)
+{
+ const GElf_Sym *lsym = (const GElf_Sym *)l;
+ const GElf_Sym *rsym = (const GElf_Sym *)r;
+
+ if (lsym->st_value < rsym->st_value)
+ return -1;
+ else if (lsym->st_value > rsym->st_value)
+ return 1;
+ else
+ return 0;
+}
+
+static int load_elf_maps_section(struct bpf_map_data *maps, int maps_shndx,
+ Elf *elf, Elf_Data *symbols, int strtabidx)
+{
+ int map_sz_elf, map_sz_copy;
+ bool validate_zero = false;
+ Elf_Data *data_maps;
+ int i, nr_maps;
+ GElf_Sym *sym;
+ Elf_Scn *scn;
+ int copy_sz;
+
+ if (maps_shndx < 0)
+ return -EINVAL;
+ if (!symbols)
+ return -EINVAL;
+
+ /* Get data for maps section via elf index */
+ scn = elf_getscn(elf, maps_shndx);
+ if (scn)
+ data_maps = elf_getdata(scn, NULL);
+ if (!scn || !data_maps) {
+ printf("Failed to get Elf_Data from maps section %d\n",
+ maps_shndx);
+ return -EINVAL;
+ }
+
+ /* For each map get corrosponding symbol table entry */
+ sym = calloc(MAX_MAPS+1, sizeof(GElf_Sym));
+ for (i = 0, nr_maps = 0; i < symbols->d_size / sizeof(GElf_Sym); i++) {
+ assert(nr_maps < MAX_MAPS+1);
+ if (!gelf_getsym(symbols, i, &sym[nr_maps]))
+ continue;
+ if (sym[nr_maps].st_shndx != maps_shndx)
+ continue;
+ /* Only increment iif maps section */
+ nr_maps++;
+ }
+
+ /* Align to map_fd[] order, via sort on offset in sym.st_value */
+ qsort(sym, nr_maps, sizeof(GElf_Sym), cmp_symbols);
+
+ /* Keeping compatible with ELF maps section changes
+ * ------------------------------------------------
+ * The program size of struct bpf_load_map_def is known by loader
+ * code, but struct stored in ELF file can be different.
+ *
+ * Unfortunately sym[i].st_size is zero. To calculate the
+ * struct size stored in the ELF file, assume all struct have
+ * the same size, and simply divide with number of map
+ * symbols.
+ */
+ map_sz_elf = data_maps->d_size / nr_maps;
+ map_sz_copy = sizeof(struct bpf_load_map_def);
+ if (map_sz_elf < map_sz_copy) {
+ /*
+ * Backward compat, loading older ELF file with
+ * smaller struct, keeping remaining bytes zero.
+ */
+ map_sz_copy = map_sz_elf;
+ } else if (map_sz_elf > map_sz_copy) {
+ /*
+ * Forward compat, loading newer ELF file with larger
+ * struct with unknown features. Assume zero means
+ * feature not used. Thus, validate rest of struct
+ * data is zero.
+ */
+ validate_zero = true;
+ }
+
+ /* Memcpy relevant part of ELF maps data to loader maps */
+ for (i = 0; i < nr_maps; i++) {
+ struct bpf_load_map_def *def;
+ unsigned char *addr, *end;
+ const char *map_name;
+ size_t offset;
+
+ map_name = elf_strptr(elf, strtabidx, sym[i].st_name);
+ maps[i].name = strdup(map_name);
+ if (!maps[i].name) {
+ printf("strdup(%s): %s(%d)\n", map_name,
+ strerror(errno), errno);
+ free(sym);
+ return -errno;
+ }
+
+ /* Symbol value is offset into ELF maps section data area */
+ offset = sym[i].st_value;
+ def = (struct bpf_load_map_def *)(data_maps->d_buf + offset);
+ maps[i].elf_offset = offset;
+ memset(&maps[i].def, 0, sizeof(struct bpf_load_map_def));
+ memcpy(&maps[i].def, def, map_sz_copy);
+
+ /* Verify no newer features were requested */
+ if (validate_zero) {
+ addr = (unsigned char *) def + map_sz_copy;
+ end = (unsigned char *) def + map_sz_elf;
+ for (; addr < end; addr++) {
+ if (*addr != 0) {
+ free(sym);
+ return -EFBIG;
+ }
+ }
+ }
+ }
+
+ free(sym);
+ return nr_maps;
+}
+
+static int do_load_bpf_file(const char *path, fixup_map_cb fixup_map)
+{
+ int fd, i, ret, maps_shndx = -1, strtabidx = -1;
+ Elf *elf;
+ GElf_Ehdr ehdr;
+ GElf_Shdr shdr, shdr_prog;
+ Elf_Data *data, *data_prog, *data_maps = NULL, *symbols = NULL;
+ char *shname, *shname_prog;
+ int nr_maps = 0;
+
+ /* reset global variables */
+ kern_version = 0;
+ memset(license, 0, sizeof(license));
+ memset(processed_sec, 0, sizeof(processed_sec));
+
+ 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 = write_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) {
+ int j;
+
+ maps_shndx = i;
+ data_maps = data;
+ for (j = 0; j < MAX_MAPS; j++)
+ map_data[j].fd = -1;
+ } else if (shdr.sh_type == SHT_SYMTAB) {
+ strtabidx = shdr.sh_link;
+ symbols = data;
+ }
+ }
+
+ ret = 1;
+
+ if (!symbols) {
+ printf("missing SHT_SYMTAB section\n");
+ goto done;
+ }
+
+ if (data_maps) {
+ nr_maps = load_elf_maps_section(map_data, maps_shndx,
+ elf, symbols, strtabidx);
+ if (nr_maps < 0) {
+ printf("Error: Failed loading ELF maps (errno:%d):%s\n",
+ nr_maps, strerror(-nr_maps));
+ goto done;
+ }
+ if (load_maps(map_data, nr_maps, fixup_map))
+ goto done;
+ map_data_count = nr_maps;
+
+ processed_sec[maps_shndx] = true;
+ }
+
+ /* process all relo sections, and rewrite bpf insns for 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 (shdr.sh_type == SHT_REL) {
+ struct bpf_insn *insns;
+
+ /* locate prog sec that need map fixup (relocations) */
+ if (get_sec(elf, shdr.sh_info, &ehdr, &shname_prog,
+ &shdr_prog, &data_prog))
+ continue;
+
+ if (shdr_prog.sh_type != SHT_PROGBITS ||
+ !(shdr_prog.sh_flags & SHF_EXECINSTR))
+ continue;
+
+ insns = (struct bpf_insn *) data_prog->d_buf;
+ processed_sec[i] = true; /* relo section */
+
+ if (parse_relo_and_apply(data, symbols, &shdr, insns,
+ map_data, nr_maps))
+ continue;
+ }
+ }
+
+ /* load programs */
+ 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, "tracepoint/", 11) == 0 ||
+ memcmp(shname, "raw_tracepoint/", 15) == 0 ||
+ memcmp(shname, "xdp", 3) == 0 ||
+ memcmp(shname, "perf_event", 10) == 0 ||
+ memcmp(shname, "socket", 6) == 0 ||
+ memcmp(shname, "cgroup/", 7) == 0 ||
+ memcmp(shname, "sockops", 7) == 0 ||
+ memcmp(shname, "sk_skb", 6) == 0 ||
+ memcmp(shname, "sk_msg", 6) == 0) {
+ ret = load_and_attach(shname, data->d_buf,
+ data->d_size);
+ if (ret != 0)
+ goto done;
+ }
+ }
+
+done:
+ close(fd);
+ return ret;
+}
+
+int load_bpf_file(char *path)
+{
+ return do_load_bpf_file(path, NULL);
+}
+
+int load_bpf_file_fixup_map(const char *path, fixup_map_cb fixup_map)
+{
+ return do_load_bpf_file(path, fixup_map);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-14 22:14:13 +0000