[deliverable/linux.git] / tools / lib / bpf / libbpf.c

/*
 * Common eBPF ELF object loading operations.
 *
 * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
 * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
 * Copyright (C) 2015 Huawei Inc.
 */

#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <inttypes.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <asm/unistd.h>
#include <linux/kernel.h>
#include <linux/bpf.h>
#include <libelf.h>
#include <gelf.h>

#include "libbpf.h"

#define __printf(a, b)	__attribute__((format(printf, a, b)))

__printf(1, 2)
static int __base_pr(const char *format, ...)
{
	va_list args;
	int err;

	va_start(args, format);
	err = vfprintf(stderr, format, args);
	va_end(args);
	return err;
}

static __printf(1, 2) libbpf_print_fn_t __pr_warning = __base_pr;
static __printf(1, 2) libbpf_print_fn_t __pr_info = __base_pr;
static __printf(1, 2) libbpf_print_fn_t __pr_debug;

#define __pr(func, fmt, ...)	\
do {				\
	if ((func))		\
		(func)("libbpf: " fmt, ##__VA_ARGS__); \
} while (0)

#define pr_warning(fmt, ...)	__pr(__pr_warning, fmt, ##__VA_ARGS__)
#define pr_info(fmt, ...)	__pr(__pr_info, fmt, ##__VA_ARGS__)
#define pr_debug(fmt, ...)	__pr(__pr_debug, fmt, ##__VA_ARGS__)

void libbpf_set_print(libbpf_print_fn_t warn,
		      libbpf_print_fn_t info,
		      libbpf_print_fn_t debug)
{
	__pr_warning = warn;
	__pr_info = info;
	__pr_debug = debug;
}

/* Copied from tools/perf/util/util.h */
#ifndef zfree
# define zfree(ptr) ({ free(*ptr); *ptr = NULL; })
#endif

#ifndef zclose
# define zclose(fd) ({			\
	int ___err = 0;			\
	if ((fd) >= 0)			\
		___err = close((fd));	\
	fd = -1;			\
	___err; })
#endif

#ifdef HAVE_LIBELF_MMAP_SUPPORT
# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ_MMAP
#else
# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ
#endif

/*
 * bpf_prog should be a better name but it has been used in
 * linux/filter.h.
 */
struct bpf_program {
	/* Index in elf obj file, for relocation use. */
	int idx;
	char *section_name;
	struct bpf_insn *insns;
	size_t insns_cnt;

	struct {
		int insn_idx;
		int map_idx;
	} *reloc_desc;
	int nr_reloc;
};

struct bpf_object {
	char license[64];
	u32 kern_version;
	void *maps_buf;
	size_t maps_buf_sz;

	struct bpf_program *programs;
	size_t nr_programs;

	/*
	 * Information when doing elf related work. Only valid if fd
	 * is valid.
	 */
	struct {
		int fd;
		void *obj_buf;
		size_t obj_buf_sz;
		Elf *elf;
		GElf_Ehdr ehdr;
		Elf_Data *symbols;
		struct {
			GElf_Shdr shdr;
			Elf_Data *data;
		} *reloc;
		int nr_reloc;
	} efile;
	char path[];
};
#define obj_elf_valid(o)	((o)->efile.elf)

static void bpf_program__exit(struct bpf_program *prog)
{
	if (!prog)
		return;

	zfree(&prog->section_name);
	zfree(&prog->insns);
	zfree(&prog->reloc_desc);

	prog->nr_reloc = 0;
	prog->insns_cnt = 0;
	prog->idx = -1;
}

static int
bpf_program__init(void *data, size_t size, char *name, int idx,
		    struct bpf_program *prog)
{
	if (size < sizeof(struct bpf_insn)) {
		pr_warning("corrupted section '%s'\n", name);
		return -EINVAL;
	}

	bzero(prog, sizeof(*prog));

	prog->section_name = strdup(name);
	if (!prog->section_name) {
		pr_warning("failed to alloc name for prog %s\n",
			   name);
		goto errout;
	}

	prog->insns = malloc(size);
	if (!prog->insns) {
		pr_warning("failed to alloc insns for %s\n", name);
		goto errout;
	}
	prog->insns_cnt = size / sizeof(struct bpf_insn);
	memcpy(prog->insns, data,
	       prog->insns_cnt * sizeof(struct bpf_insn));
	prog->idx = idx;

	return 0;
errout:
	bpf_program__exit(prog);
	return -ENOMEM;
}

static int
bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,
			char *name, int idx)
{
	struct bpf_program prog, *progs;
	int nr_progs, err;

	err = bpf_program__init(data, size, name, idx, &prog);
	if (err)
		return err;

	progs = obj->programs;
	nr_progs = obj->nr_programs;

	progs = realloc(progs, sizeof(progs[0]) * (nr_progs + 1));
	if (!progs) {
		/*
		 * In this case the original obj->programs
		 * is still valid, so don't need special treat for
		 * bpf_close_object().
		 */
		pr_warning("failed to alloc a new program '%s'\n",
			   name);
		bpf_program__exit(&prog);
		return -ENOMEM;
	}

	pr_debug("found program %s\n", prog.section_name);
	obj->programs = progs;
	obj->nr_programs = nr_progs + 1;
	progs[nr_progs] = prog;
	return 0;
}

static struct bpf_object *bpf_object__new(const char *path,
					  void *obj_buf,
					  size_t obj_buf_sz)
{
	struct bpf_object *obj;

	obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1);
	if (!obj) {
		pr_warning("alloc memory failed for %s\n", path);
		return NULL;
	}

	strcpy(obj->path, path);
	obj->efile.fd = -1;

	/*
	 * Caller of this function should also calls
	 * bpf_object__elf_finish() after data collection to return
	 * obj_buf to user. If not, we should duplicate the buffer to
	 * avoid user freeing them before elf finish.
	 */
	obj->efile.obj_buf = obj_buf;
	obj->efile.obj_buf_sz = obj_buf_sz;

	return obj;
}

static void bpf_object__elf_finish(struct bpf_object *obj)
{
	if (!obj_elf_valid(obj))
		return;

	if (obj->efile.elf) {
		elf_end(obj->efile.elf);
		obj->efile.elf = NULL;
	}
	obj->efile.symbols = NULL;

	zfree(&obj->efile.reloc);
	obj->efile.nr_reloc = 0;
	zclose(obj->efile.fd);
	obj->efile.obj_buf = NULL;
	obj->efile.obj_buf_sz = 0;
}

static int bpf_object__elf_init(struct bpf_object *obj)
{
	int err = 0;
	GElf_Ehdr *ep;

	if (obj_elf_valid(obj)) {
		pr_warning("elf init: internal error\n");
		return -EEXIST;
	}

	if (obj->efile.obj_buf_sz > 0) {
		/*
		 * obj_buf should have been validated by
		 * bpf_object__open_buffer().
		 */
		obj->efile.elf = elf_memory(obj->efile.obj_buf,
					    obj->efile.obj_buf_sz);
	} else {
		obj->efile.fd = open(obj->path, O_RDONLY);
		if (obj->efile.fd < 0) {
			pr_warning("failed to open %s: %s\n", obj->path,
					strerror(errno));
			return -errno;
		}

		obj->efile.elf = elf_begin(obj->efile.fd,
				LIBBPF_ELF_C_READ_MMAP,
				NULL);
	}

	if (!obj->efile.elf) {
		pr_warning("failed to open %s as ELF file\n",
				obj->path);
		err = -EINVAL;
		goto errout;
	}

	if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) {
		pr_warning("failed to get EHDR from %s\n",
				obj->path);
		err = -EINVAL;
		goto errout;
	}
	ep = &obj->efile.ehdr;

	if ((ep->e_type != ET_REL) || (ep->e_machine != 0)) {
		pr_warning("%s is not an eBPF object file\n",
			obj->path);
		err = -EINVAL;
		goto errout;
	}

	return 0;
errout:
	bpf_object__elf_finish(obj);
	return err;
}

static int
bpf_object__check_endianness(struct bpf_object *obj)
{
	static unsigned int const endian = 1;

	switch (obj->efile.ehdr.e_ident[EI_DATA]) {
	case ELFDATA2LSB:
		/* We are big endian, BPF obj is little endian. */
		if (*(unsigned char const *)&endian != 1)
			goto mismatch;
		break;

	case ELFDATA2MSB:
		/* We are little endian, BPF obj is big endian. */
		if (*(unsigned char const *)&endian != 0)
			goto mismatch;
		break;
	default:
		return -EINVAL;
	}

	return 0;

mismatch:
	pr_warning("Error: endianness mismatch.\n");
	return -EINVAL;
}

static int
bpf_object__init_license(struct bpf_object *obj,
			 void *data, size_t size)
{
	memcpy(obj->license, data,
	       min(size, sizeof(obj->license) - 1));
	pr_debug("license of %s is %s\n", obj->path, obj->license);
	return 0;
}

static int
bpf_object__init_kversion(struct bpf_object *obj,
			  void *data, size_t size)
{
	u32 kver;

	if (size != sizeof(kver)) {
		pr_warning("invalid kver section in %s\n", obj->path);
		return -EINVAL;
	}
	memcpy(&kver, data, sizeof(kver));
	obj->kern_version = kver;
	pr_debug("kernel version of %s is %x\n", obj->path,
		 obj->kern_version);
	return 0;
}

static int
bpf_object__init_maps(struct bpf_object *obj, void *data,
		      size_t size)
{
	if (size == 0) {
		pr_debug("%s doesn't need map definition\n",
			 obj->path);
		return 0;
	}

	obj->maps_buf = malloc(size);
	if (!obj->maps_buf) {
		pr_warning("malloc maps failed: %s\n", obj->path);
		return -ENOMEM;
	}

	obj->maps_buf_sz = size;
	memcpy(obj->maps_buf, data, size);
	pr_debug("maps in %s: %ld bytes\n", obj->path, (long)size);
	return 0;
}

static int bpf_object__elf_collect(struct bpf_object *obj)
{
	Elf *elf = obj->efile.elf;
	GElf_Ehdr *ep = &obj->efile.ehdr;
	Elf_Scn *scn = NULL;
	int idx = 0, err = 0;

	/* Elf is corrupted/truncated, avoid calling elf_strptr. */
	if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL)) {
		pr_warning("failed to get e_shstrndx from %s\n",
			   obj->path);
		return -EINVAL;
	}

	while ((scn = elf_nextscn(elf, scn)) != NULL) {
		char *name;
		GElf_Shdr sh;
		Elf_Data *data;

		idx++;
		if (gelf_getshdr(scn, &sh) != &sh) {
			pr_warning("failed to get section header from %s\n",
				   obj->path);
			err = -EINVAL;
			goto out;
		}

		name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name);
		if (!name) {
			pr_warning("failed to get section name from %s\n",
				   obj->path);
			err = -EINVAL;
			goto out;
		}

		data = elf_getdata(scn, 0);
		if (!data) {
			pr_warning("failed to get section data from %s(%s)\n",
				   name, obj->path);
			err = -EINVAL;
			goto out;
		}
		pr_debug("section %s, size %ld, link %d, flags %lx, type=%d\n",
			 name, (unsigned long)data->d_size,
			 (int)sh.sh_link, (unsigned long)sh.sh_flags,
			 (int)sh.sh_type);

		if (strcmp(name, "license") == 0)
			err = bpf_object__init_license(obj,
						       data->d_buf,
						       data->d_size);
		else if (strcmp(name, "version") == 0)
			err = bpf_object__init_kversion(obj,
							data->d_buf,
							data->d_size);
		else if (strcmp(name, "maps") == 0)
			err = bpf_object__init_maps(obj, data->d_buf,
						    data->d_size);
		else if (sh.sh_type == SHT_SYMTAB) {
			if (obj->efile.symbols) {
				pr_warning("bpf: multiple SYMTAB in %s\n",
					   obj->path);
				err = -EEXIST;
			} else
				obj->efile.symbols = data;
		} else if ((sh.sh_type == SHT_PROGBITS) &&
			   (sh.sh_flags & SHF_EXECINSTR) &&
			   (data->d_size > 0)) {
			err = bpf_object__add_program(obj, data->d_buf,
						      data->d_size, name, idx);
			if (err) {
				char errmsg[128];
				strerror_r(-err, errmsg, sizeof(errmsg));
				pr_warning("failed to alloc program %s (%s): %s",
					   name, obj->path, errmsg);
			}
		} else if (sh.sh_type == SHT_REL) {
			void *reloc = obj->efile.reloc;
			int nr_reloc = obj->efile.nr_reloc + 1;

			reloc = realloc(reloc,
					sizeof(*obj->efile.reloc) * nr_reloc);
			if (!reloc) {
				pr_warning("realloc failed\n");
				err = -ENOMEM;
			} else {
				int n = nr_reloc - 1;

				obj->efile.reloc = reloc;
				obj->efile.nr_reloc = nr_reloc;

				obj->efile.reloc[n].shdr = sh;
				obj->efile.reloc[n].data = data;
			}
		}
		if (err)
			goto out;
	}
out:
	return err;
}

static struct bpf_program *
bpf_object__find_prog_by_idx(struct bpf_object *obj, int idx)
{
	struct bpf_program *prog;
	size_t i;

	for (i = 0; i < obj->nr_programs; i++) {
		prog = &obj->programs[i];
		if (prog->idx == idx)
			return prog;
	}
	return NULL;
}

static int
bpf_program__collect_reloc(struct bpf_program *prog,
			   size_t nr_maps, GElf_Shdr *shdr,
			   Elf_Data *data, Elf_Data *symbols)
{
	int i, nrels;

	pr_debug("collecting relocating info for: '%s'\n",
		 prog->section_name);
	nrels = shdr->sh_size / shdr->sh_entsize;

	prog->reloc_desc = malloc(sizeof(*prog->reloc_desc) * nrels);
	if (!prog->reloc_desc) {
		pr_warning("failed to alloc memory in relocation\n");
		return -ENOMEM;
	}
	prog->nr_reloc = nrels;

	for (i = 0; i < nrels; i++) {
		GElf_Sym sym;
		GElf_Rel rel;
		unsigned int insn_idx;
		struct bpf_insn *insns = prog->insns;
		size_t map_idx;

		if (!gelf_getrel(data, i, &rel)) {
			pr_warning("relocation: failed to get %d reloc\n", i);
			return -EINVAL;
		}

		insn_idx = rel.r_offset / sizeof(struct bpf_insn);
		pr_debug("relocation: insn_idx=%u\n", insn_idx);

		if (!gelf_getsym(symbols,
				 GELF_R_SYM(rel.r_info),
				 &sym)) {
			pr_warning("relocation: symbol %"PRIx64" not found\n",
				   GELF_R_SYM(rel.r_info));
			return -EINVAL;
		}

		if (insns[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) {
			pr_warning("bpf: relocation: invalid relo for insns[%d].code 0x%x\n",
				   insn_idx, insns[insn_idx].code);
			return -EINVAL;
		}

		map_idx = sym.st_value / sizeof(struct bpf_map_def);
		if (map_idx >= nr_maps) {
			pr_warning("bpf relocation: map_idx %d large than %d\n",
				   (int)map_idx, (int)nr_maps - 1);
			return -EINVAL;
		}

		prog->reloc_desc[i].insn_idx = insn_idx;
		prog->reloc_desc[i].map_idx = map_idx;
	}
	return 0;
}

static int bpf_object__collect_reloc(struct bpf_object *obj)
{
	int i, err;

	if (!obj_elf_valid(obj)) {
		pr_warning("Internal error: elf object is closed\n");
		return -EINVAL;
	}

	for (i = 0; i < obj->efile.nr_reloc; i++) {
		GElf_Shdr *shdr = &obj->efile.reloc[i].shdr;
		Elf_Data *data = obj->efile.reloc[i].data;
		int idx = shdr->sh_info;
		struct bpf_program *prog;
		size_t nr_maps = obj->maps_buf_sz /
				 sizeof(struct bpf_map_def);

		if (shdr->sh_type != SHT_REL) {
			pr_warning("internal error at %d\n", __LINE__);
			return -EINVAL;
		}

		prog = bpf_object__find_prog_by_idx(obj, idx);
		if (!prog) {
			pr_warning("relocation failed: no %d section\n",
				   idx);
			return -ENOENT;
		}

		err = bpf_program__collect_reloc(prog, nr_maps,
						 shdr, data,
						 obj->efile.symbols);
		if (err)
			return -EINVAL;
	}
	return 0;
}

static int bpf_object__validate(struct bpf_object *obj)
{
	if (obj->kern_version == 0) {
		pr_warning("%s doesn't provide kernel version\n",
			   obj->path);
		return -EINVAL;
	}
	return 0;
}

static struct bpf_object *
__bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz)
{
	struct bpf_object *obj;

	if (elf_version(EV_CURRENT) == EV_NONE) {
		pr_warning("failed to init libelf for %s\n", path);
		return NULL;
	}

	obj = bpf_object__new(path, obj_buf, obj_buf_sz);
	if (!obj)
		return NULL;

	if (bpf_object__elf_init(obj))
		goto out;
	if (bpf_object__check_endianness(obj))
		goto out;
	if (bpf_object__elf_collect(obj))
		goto out;
	if (bpf_object__collect_reloc(obj))
		goto out;
	if (bpf_object__validate(obj))
		goto out;

	bpf_object__elf_finish(obj);
	return obj;
out:
	bpf_object__close(obj);
	return NULL;
}

struct bpf_object *bpf_object__open(const char *path)
{
	/* param validation */
	if (!path)
		return NULL;

	pr_debug("loading %s\n", path);

	return __bpf_object__open(path, NULL, 0);
}

struct bpf_object *bpf_object__open_buffer(void *obj_buf,
					   size_t obj_buf_sz)
{
	/* param validation */
	if (!obj_buf || obj_buf_sz <= 0)
		return NULL;

	pr_debug("loading object from buffer\n");

	return __bpf_object__open("[buffer]", obj_buf, obj_buf_sz);
}

void bpf_object__close(struct bpf_object *obj)
{
	size_t i;

	if (!obj)
		return;

	bpf_object__elf_finish(obj);

	zfree(&obj->maps_buf);

	if (obj->programs && obj->nr_programs) {
		for (i = 0; i < obj->nr_programs; i++)
			bpf_program__exit(&obj->programs[i]);
	}
	zfree(&obj->programs);

	free(obj);
}
Commit	Line	Data
1b76c13e WN	1	/*
	2	* Common eBPF ELF object loading operations.
	3	*
	4	* Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
	5	* Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
	6	* Copyright (C) 2015 Huawei Inc.
	7	*/
	8
	9	#include <stdlib.h>
b3f59d66 WN	10	#include <stdio.h>
b3f59d66 WN	11	#include <stdarg.h>
34090915	12	#include <inttypes.h>
b3f59d66	13	#include <string.h>
1b76c13e	14	#include <unistd.h>
1a5e3fb1 WN	15	#include <fcntl.h>
1a5e3fb1 WN	16	#include <errno.h>
1b76c13e	17	#include <asm/unistd.h>
cb1e5e96	18	#include <linux/kernel.h>
1b76c13e	19	#include <linux/bpf.h>
1a5e3fb1 WN	20	#include <libelf.h>
1a5e3fb1 WN	21	#include <gelf.h>
1b76c13e WN	22
1b76c13e WN	23	#include "libbpf.h"
b3f59d66 WN	24
	25	#define __printf(a, b) __attribute__((format(printf, a, b)))
	26
	27	__printf(1, 2)
	28	static int __base_pr(const char *format, ...)
	29	{
	30	va_list args;
	31	int err;
	32
	33	va_start(args, format);
	34	err = vfprintf(stderr, format, args);
	35	va_end(args);
	36	return err;
	37	}
	38
	39	static __printf(1, 2) libbpf_print_fn_t __pr_warning = __base_pr;
	40	static __printf(1, 2) libbpf_print_fn_t __pr_info = __base_pr;
	41	static __printf(1, 2) libbpf_print_fn_t __pr_debug;
	42
	43	#define __pr(func, fmt, ...) \
	44	do { \
	45	if ((func)) \
	46	(func)("libbpf: " fmt, ##__VA_ARGS__); \
	47	} while (0)
	48
	49	#define pr_warning(fmt, ...) __pr(__pr_warning, fmt, ##__VA_ARGS__)
	50	#define pr_info(fmt, ...) __pr(__pr_info, fmt, ##__VA_ARGS__)
	51	#define pr_debug(fmt, ...) __pr(__pr_debug, fmt, ##__VA_ARGS__)
	52
	53	void libbpf_set_print(libbpf_print_fn_t warn,
	54	libbpf_print_fn_t info,
	55	libbpf_print_fn_t debug)
	56	{
	57	__pr_warning = warn;
	58	__pr_info = info;
	59	__pr_debug = debug;
	60	}
1a5e3fb1 WN	61
	62	/* Copied from tools/perf/util/util.h */
	63	#ifndef zfree
	64	# define zfree(ptr) ({ free(ptr); ptr = NULL; })
	65	#endif
	66
	67	#ifndef zclose
	68	# define zclose(fd) ({ \
	69	int ___err = 0; \
	70	if ((fd) >= 0) \
	71	___err = close((fd)); \
	72	fd = -1; \
	73	___err; })
	74	#endif
	75
	76	#ifdef HAVE_LIBELF_MMAP_SUPPORT
	77	# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ_MMAP
	78	#else
	79	# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ
	80	#endif
	81
a5b8bd47 WN	82	/*
	83	* bpf_prog should be a better name but it has been used in
	84	* linux/filter.h.
	85	*/
	86	struct bpf_program {
	87	/* Index in elf obj file, for relocation use. */
	88	int idx;
	89	char *section_name;
	90	struct bpf_insn *insns;
	91	size_t insns_cnt;
34090915 WN	92
	93	struct {
	94	int insn_idx;
	95	int map_idx;
	96	} *reloc_desc;
	97	int nr_reloc;
a5b8bd47 WN	98	};
a5b8bd47 WN	99
1a5e3fb1	100	struct bpf_object {
cb1e5e96 WN	101	char license[64];
cb1e5e96 WN	102	u32 kern_version;
0b3d1efa WN	103	void *maps_buf;
	104	size_t maps_buf_sz;
	105
a5b8bd47 WN	106	struct bpf_program *programs;
	107	size_t nr_programs;
	108
1a5e3fb1 WN	109	/*
	110	* Information when doing elf related work. Only valid if fd
	111	* is valid.
	112	*/
	113	struct {
	114	int fd;
6c956392 WN	115	void *obj_buf;
6c956392 WN	116	size_t obj_buf_sz;
1a5e3fb1 WN	117	Elf *elf;
1a5e3fb1 WN	118	GElf_Ehdr ehdr;
bec7d68c	119	Elf_Data *symbols;
b62f06e8 WN	120	struct {
	121	GElf_Shdr shdr;
	122	Elf_Data *data;
	123	} *reloc;
	124	int nr_reloc;
1a5e3fb1 WN	125	} efile;
	126	char path[];
	127	};
	128	#define obj_elf_valid(o) ((o)->efile.elf)
	129
a5b8bd47 WN	130	static void bpf_program__exit(struct bpf_program *prog)
	131	{
	132	if (!prog)
	133	return;
	134
	135	zfree(&prog->section_name);
	136	zfree(&prog->insns);
34090915 WN	137	zfree(&prog->reloc_desc);
	138
	139	prog->nr_reloc = 0;
a5b8bd47 WN	140	prog->insns_cnt = 0;
	141	prog->idx = -1;
	142	}
	143
	144	static int
	145	bpf_program__init(void data, size_t size, char name, int idx,
	146	struct bpf_program *prog)
	147	{
	148	if (size < sizeof(struct bpf_insn)) {
	149	pr_warning("corrupted section '%s'\n", name);
	150	return -EINVAL;
	151	}
	152
	153	bzero(prog, sizeof(*prog));
	154
	155	prog->section_name = strdup(name);
	156	if (!prog->section_name) {
	157	pr_warning("failed to alloc name for prog %s\n",
	158	name);
	159	goto errout;
	160	}
	161
	162	prog->insns = malloc(size);
	163	if (!prog->insns) {
	164	pr_warning("failed to alloc insns for %s\n", name);
	165	goto errout;
	166	}
	167	prog->insns_cnt = size / sizeof(struct bpf_insn);
	168	memcpy(prog->insns, data,
	169	prog->insns_cnt * sizeof(struct bpf_insn));
	170	prog->idx = idx;
	171
	172	return 0;
	173	errout:
	174	bpf_program__exit(prog);
	175	return -ENOMEM;
	176	}
	177
	178	static int
	179	bpf_object__add_program(struct bpf_object obj, void data, size_t size,
	180	char *name, int idx)
	181	{
	182	struct bpf_program prog, *progs;
	183	int nr_progs, err;
	184
	185	err = bpf_program__init(data, size, name, idx, &prog);
	186	if (err)
	187	return err;
	188
	189	progs = obj->programs;
	190	nr_progs = obj->nr_programs;
	191
	192	progs = realloc(progs, sizeof(progs[0]) * (nr_progs + 1));
	193	if (!progs) {
	194	/*
	195	* In this case the original obj->programs
	196	* is still valid, so don't need special treat for
	197	* bpf_close_object().
	198	*/
	199	pr_warning("failed to alloc a new program '%s'\n",
	200	name);
	201	bpf_program__exit(&prog);
	202	return -ENOMEM;
	203	}
204
205	pr_debug("found program %s\n", prog.section_name);
206	obj->programs = progs;
207	obj->nr_programs = nr_progs + 1;
208	progs[nr_progs] = prog;
209	return 0;
210	}
211
6c956392 WN	212	static struct bpf_object bpf_object__new(const char path,
	213	void *obj_buf,
	214	size_t obj_buf_sz)
1a5e3fb1 WN	215	{
	216	struct bpf_object *obj;
	217
	218	obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1);
	219	if (!obj) {
	220	pr_warning("alloc memory failed for %s\n", path);
	221	return NULL;
	222	}
	223
	224	strcpy(obj->path, path);
	225	obj->efile.fd = -1;
6c956392 WN	226
	227	/*
	228	* Caller of this function should also calls
	229	* bpf_object__elf_finish() after data collection to return
	230	* obj_buf to user. If not, we should duplicate the buffer to
	231	* avoid user freeing them before elf finish.
	232	*/
	233	obj->efile.obj_buf = obj_buf;
	234	obj->efile.obj_buf_sz = obj_buf_sz;
	235
1a5e3fb1 WN	236	return obj;
	237	}
	238
	239	static void bpf_object__elf_finish(struct bpf_object *obj)
	240	{
	241	if (!obj_elf_valid(obj))
	242	return;
	243
	244	if (obj->efile.elf) {
	245	elf_end(obj->efile.elf);
	246	obj->efile.elf = NULL;
	247	}
bec7d68c	248	obj->efile.symbols = NULL;
b62f06e8 WN	249
	250	zfree(&obj->efile.reloc);
	251	obj->efile.nr_reloc = 0;
1a5e3fb1	252	zclose(obj->efile.fd);
6c956392 WN	253	obj->efile.obj_buf = NULL;
6c956392 WN	254	obj->efile.obj_buf_sz = 0;
1a5e3fb1 WN	255	}
	256
	257	static int bpf_object__elf_init(struct bpf_object *obj)
	258	{
	259	int err = 0;
	260	GElf_Ehdr *ep;
	261
	262	if (obj_elf_valid(obj)) {
	263	pr_warning("elf init: internal error\n");
	264	return -EEXIST;
	265	}
	266
6c956392 WN	267	if (obj->efile.obj_buf_sz > 0) {
	268	/*
	269	* obj_buf should have been validated by
	270	* bpf_object__open_buffer().
	271	*/
	272	obj->efile.elf = elf_memory(obj->efile.obj_buf,
	273	obj->efile.obj_buf_sz);
	274	} else {
	275	obj->efile.fd = open(obj->path, O_RDONLY);
	276	if (obj->efile.fd < 0) {
	277	pr_warning("failed to open %s: %s\n", obj->path,
	278	strerror(errno));
	279	return -errno;
	280	}
	281
	282	obj->efile.elf = elf_begin(obj->efile.fd,
	283	LIBBPF_ELF_C_READ_MMAP,
	284	NULL);
1a5e3fb1 WN	285	}
1a5e3fb1 WN	286
1a5e3fb1 WN	287	if (!obj->efile.elf) {
	288	pr_warning("failed to open %s as ELF file\n",
	289	obj->path);
	290	err = -EINVAL;
	291	goto errout;
	292	}
	293
	294	if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) {
	295	pr_warning("failed to get EHDR from %s\n",
	296	obj->path);
	297	err = -EINVAL;
	298	goto errout;
	299	}
	300	ep = &obj->efile.ehdr;
	301
	302	if ((ep->e_type != ET_REL) \|\| (ep->e_machine != 0)) {
	303	pr_warning("%s is not an eBPF object file\n",
	304	obj->path);
	305	err = -EINVAL;
	306	goto errout;
	307	}
	308
	309	return 0;
	310	errout:
	311	bpf_object__elf_finish(obj);
	312	return err;
	313	}
	314
cc4228d5 WN	315	static int
	316	bpf_object__check_endianness(struct bpf_object *obj)
	317	{
	318	static unsigned int const endian = 1;
	319
	320	switch (obj->efile.ehdr.e_ident[EI_DATA]) {
	321	case ELFDATA2LSB:
	322	/* We are big endian, BPF obj is little endian. */
	323	if ((unsigned char const )&endian != 1)
	324	goto mismatch;
	325	break;
	326
	327	case ELFDATA2MSB:
	328	/* We are little endian, BPF obj is big endian. */
	329	if ((unsigned char const )&endian != 0)
	330	goto mismatch;
	331	break;
	332	default:
	333	return -EINVAL;
	334	}
	335
	336	return 0;
	337
	338	mismatch:
	339	pr_warning("Error: endianness mismatch.\n");
	340	return -EINVAL;
	341	}
	342
cb1e5e96 WN	343	static int
	344	bpf_object__init_license(struct bpf_object *obj,
	345	void *data, size_t size)
	346	{
	347	memcpy(obj->license, data,
	348	min(size, sizeof(obj->license) - 1));
	349	pr_debug("license of %s is %s\n", obj->path, obj->license);
	350	return 0;
	351	}
	352
	353	static int
	354	bpf_object__init_kversion(struct bpf_object *obj,
	355	void *data, size_t size)
	356	{
	357	u32 kver;
	358
	359	if (size != sizeof(kver)) {
	360	pr_warning("invalid kver section in %s\n", obj->path);
	361	return -EINVAL;
	362	}
	363	memcpy(&kver, data, sizeof(kver));
	364	obj->kern_version = kver;
	365	pr_debug("kernel version of %s is %x\n", obj->path,
	366	obj->kern_version);
	367	return 0;
	368	}
	369
0b3d1efa WN	370	static int
	371	bpf_object__init_maps(struct bpf_object obj, void data,
	372	size_t size)
	373	{
	374	if (size == 0) {
	375	pr_debug("%s doesn't need map definition\n",
	376	obj->path);
	377	return 0;
	378	}
	379
	380	obj->maps_buf = malloc(size);
	381	if (!obj->maps_buf) {
	382	pr_warning("malloc maps failed: %s\n", obj->path);
	383	return -ENOMEM;
	384	}
	385
	386	obj->maps_buf_sz = size;
	387	memcpy(obj->maps_buf, data, size);
	388	pr_debug("maps in %s: %ld bytes\n", obj->path, (long)size);
	389	return 0;
	390	}
	391
29603665 WN	392	static int bpf_object__elf_collect(struct bpf_object *obj)
	393	{
	394	Elf *elf = obj->efile.elf;
	395	GElf_Ehdr *ep = &obj->efile.ehdr;
	396	Elf_Scn *scn = NULL;
	397	int idx = 0, err = 0;
	398
	399	/* Elf is corrupted/truncated, avoid calling elf_strptr. */
	400	if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL)) {
	401	pr_warning("failed to get e_shstrndx from %s\n",
	402	obj->path);
	403	return -EINVAL;
	404	}
	405
	406	while ((scn = elf_nextscn(elf, scn)) != NULL) {
	407	char *name;
	408	GElf_Shdr sh;
	409	Elf_Data *data;
	410
	411	idx++;
	412	if (gelf_getshdr(scn, &sh) != &sh) {
	413	pr_warning("failed to get section header from %s\n",
	414	obj->path);
	415	err = -EINVAL;
	416	goto out;
	417	}
	418
	419	name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name);
	420	if (!name) {
	421	pr_warning("failed to get section name from %s\n",
	422	obj->path);
	423	err = -EINVAL;
	424	goto out;
	425	}
	426
	427	data = elf_getdata(scn, 0);
	428	if (!data) {
	429	pr_warning("failed to get section data from %s(%s)\n",
	430	name, obj->path);
	431	err = -EINVAL;
	432	goto out;
	433	}
	434	pr_debug("section %s, size %ld, link %d, flags %lx, type=%d\n",
	435	name, (unsigned long)data->d_size,
	436	(int)sh.sh_link, (unsigned long)sh.sh_flags,
	437	(int)sh.sh_type);
cb1e5e96 WN	438
	439	if (strcmp(name, "license") == 0)
	440	err = bpf_object__init_license(obj,
	441	data->d_buf,
	442	data->d_size);
	443	else if (strcmp(name, "version") == 0)
	444	err = bpf_object__init_kversion(obj,
	445	data->d_buf,
	446	data->d_size);
0b3d1efa WN	447	else if (strcmp(name, "maps") == 0)
	448	err = bpf_object__init_maps(obj, data->d_buf,
	449	data->d_size);
bec7d68c WN	450	else if (sh.sh_type == SHT_SYMTAB) {
	451	if (obj->efile.symbols) {
	452	pr_warning("bpf: multiple SYMTAB in %s\n",
	453	obj->path);
	454	err = -EEXIST;
	455	} else
	456	obj->efile.symbols = data;
a5b8bd47 WN	457	} else if ((sh.sh_type == SHT_PROGBITS) &&
	458	(sh.sh_flags & SHF_EXECINSTR) &&
	459	(data->d_size > 0)) {
	460	err = bpf_object__add_program(obj, data->d_buf,
	461	data->d_size, name, idx);
	462	if (err) {
	463	char errmsg[128];
	464	strerror_r(-err, errmsg, sizeof(errmsg));
	465	pr_warning("failed to alloc program %s (%s): %s",
	466	name, obj->path, errmsg);
	467	}
b62f06e8 WN	468	} else if (sh.sh_type == SHT_REL) {
	469	void *reloc = obj->efile.reloc;
	470	int nr_reloc = obj->efile.nr_reloc + 1;
	471
	472	reloc = realloc(reloc,
	473	sizeof(obj->efile.reloc) nr_reloc);
	474	if (!reloc) {
	475	pr_warning("realloc failed\n");
	476	err = -ENOMEM;
	477	} else {
	478	int n = nr_reloc - 1;
	479
	480	obj->efile.reloc = reloc;
	481	obj->efile.nr_reloc = nr_reloc;
	482
	483	obj->efile.reloc[n].shdr = sh;
	484	obj->efile.reloc[n].data = data;
	485	}
bec7d68c	486	}
cb1e5e96 WN	487	if (err)
cb1e5e96 WN	488	goto out;
29603665 WN	489	}
	490	out:
	491	return err;
	492	}
	493
34090915 WN	494	static struct bpf_program *
	495	bpf_object__find_prog_by_idx(struct bpf_object *obj, int idx)
	496	{
	497	struct bpf_program *prog;
	498	size_t i;
	499
	500	for (i = 0; i < obj->nr_programs; i++) {
	501	prog = &obj->programs[i];
	502	if (prog->idx == idx)
	503	return prog;
	504	}
	505	return NULL;
	506	}
	507
	508	static int
	509	bpf_program__collect_reloc(struct bpf_program *prog,
	510	size_t nr_maps, GElf_Shdr *shdr,
	511	Elf_Data data, Elf_Data symbols)
	512	{
	513	int i, nrels;
	514
	515	pr_debug("collecting relocating info for: '%s'\n",
	516	prog->section_name);
	517	nrels = shdr->sh_size / shdr->sh_entsize;
	518
	519	prog->reloc_desc = malloc(sizeof(prog->reloc_desc) nrels);
	520	if (!prog->reloc_desc) {
	521	pr_warning("failed to alloc memory in relocation\n");
	522	return -ENOMEM;
	523	}
	524	prog->nr_reloc = nrels;
	525
	526	for (i = 0; i < nrels; i++) {
	527	GElf_Sym sym;
	528	GElf_Rel rel;
	529	unsigned int insn_idx;
	530	struct bpf_insn *insns = prog->insns;
	531	size_t map_idx;
	532
	533	if (!gelf_getrel(data, i, &rel)) {
	534	pr_warning("relocation: failed to get %d reloc\n", i);
	535	return -EINVAL;
	536	}
	537
	538	insn_idx = rel.r_offset / sizeof(struct bpf_insn);
	539	pr_debug("relocation: insn_idx=%u\n", insn_idx);
	540
	541	if (!gelf_getsym(symbols,
	542	GELF_R_SYM(rel.r_info),
	543	&sym)) {
	544	pr_warning("relocation: symbol %"PRIx64" not found\n",
	545	GELF_R_SYM(rel.r_info));
	546	return -EINVAL;
	547	}
	548
	549	if (insns[insn_idx].code != (BPF_LD \| BPF_IMM \| BPF_DW)) {
	550	pr_warning("bpf: relocation: invalid relo for insns[%d].code 0x%x\n",
	551	insn_idx, insns[insn_idx].code);
	552	return -EINVAL;
	553	}
	554
	555	map_idx = sym.st_value / sizeof(struct bpf_map_def);
	556	if (map_idx >= nr_maps) {
	557	pr_warning("bpf relocation: map_idx %d large than %d\n",
558	(int)map_idx, (int)nr_maps - 1);
559	return -EINVAL;
560	}
561
562	prog->reloc_desc[i].insn_idx = insn_idx;
563	prog->reloc_desc[i].map_idx = map_idx;
564	}
565	return 0;
566	}
567
568	static int bpf_object__collect_reloc(struct bpf_object *obj)
569	{
570	int i, err;
571
572	if (!obj_elf_valid(obj)) {
573	pr_warning("Internal error: elf object is closed\n");
574	return -EINVAL;
575	}
576
577	for (i = 0; i < obj->efile.nr_reloc; i++) {
578	GElf_Shdr *shdr = &obj->efile.reloc[i].shdr;
579	Elf_Data *data = obj->efile.reloc[i].data;
580	int idx = shdr->sh_info;
581	struct bpf_program *prog;
582	size_t nr_maps = obj->maps_buf_sz /
583	sizeof(struct bpf_map_def);
584
585	if (shdr->sh_type != SHT_REL) {
586	pr_warning("internal error at %d\n", __LINE__);
587	return -EINVAL;
588	}
589
590	prog = bpf_object__find_prog_by_idx(obj, idx);
591	if (!prog) {
592	pr_warning("relocation failed: no %d section\n",
593	idx);
594	return -ENOENT;
595	}
596
597	err = bpf_program__collect_reloc(prog, nr_maps,
598	shdr, data,
599	obj->efile.symbols);
600	if (err)
601	return -EINVAL;
602	}
603	return 0;
604	}
605
cb1e5e96 WN	606	static int bpf_object__validate(struct bpf_object *obj)
	607	{
	608	if (obj->kern_version == 0) {
	609	pr_warning("%s doesn't provide kernel version\n",
	610	obj->path);
	611	return -EINVAL;
	612	}
	613	return 0;
	614	}
	615
1a5e3fb1	616	static struct bpf_object *
6c956392	617	__bpf_object__open(const char path, void obj_buf, size_t obj_buf_sz)
1a5e3fb1 WN	618	{
	619	struct bpf_object *obj;
	620
	621	if (elf_version(EV_CURRENT) == EV_NONE) {
	622	pr_warning("failed to init libelf for %s\n", path);
	623	return NULL;
	624	}
	625
6c956392	626	obj = bpf_object__new(path, obj_buf, obj_buf_sz);
1a5e3fb1 WN	627	if (!obj)
	628	return NULL;
	629
	630	if (bpf_object__elf_init(obj))
	631	goto out;
cc4228d5 WN	632	if (bpf_object__check_endianness(obj))
cc4228d5 WN	633	goto out;
29603665 WN	634	if (bpf_object__elf_collect(obj))
29603665 WN	635	goto out;
34090915 WN	636	if (bpf_object__collect_reloc(obj))
34090915 WN	637	goto out;
cb1e5e96 WN	638	if (bpf_object__validate(obj))
cb1e5e96 WN	639	goto out;
1a5e3fb1 WN	640
	641	bpf_object__elf_finish(obj);
	642	return obj;
	643	out:
	644	bpf_object__close(obj);
	645	return NULL;
	646	}
	647
	648	struct bpf_object bpf_object__open(const char path)
	649	{
	650	/* param validation */
	651	if (!path)
	652	return NULL;
	653
	654	pr_debug("loading %s\n", path);
	655
6c956392 WN	656	return __bpf_object__open(path, NULL, 0);
	657	}
	658
	659	struct bpf_object bpf_object__open_buffer(void obj_buf,
	660	size_t obj_buf_sz)
	661	{
	662	/* param validation */
	663	if (!obj_buf \|\| obj_buf_sz <= 0)
	664	return NULL;
	665
	666	pr_debug("loading object from buffer\n");
	667
	668	return __bpf_object__open("[buffer]", obj_buf, obj_buf_sz);
1a5e3fb1 WN	669	}
	670
	671	void bpf_object__close(struct bpf_object *obj)
	672	{
a5b8bd47 WN	673	size_t i;
a5b8bd47 WN	674
1a5e3fb1 WN	675	if (!obj)
	676	return;
	677
	678	bpf_object__elf_finish(obj);
	679
0b3d1efa	680	zfree(&obj->maps_buf);
a5b8bd47 WN	681
	682	if (obj->programs && obj->nr_programs) {
	683	for (i = 0; i < obj->nr_programs; i++)
	684	bpf_program__exit(&obj->programs[i]);
	685	}
	686	zfree(&obj->programs);
	687
1a5e3fb1 WN	688	free(obj);
1a5e3fb1 WN	689	}