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Commit d7be143b authored by Andrey Ignatov's avatar Andrey Ignatov Committed by Daniel Borkmann
Browse files

libbpf: Support expected_attach_type at prog load 



Support setting `expected_attach_type` at prog load time in both
`bpf/bpf.h` and `bpf/libbpf.h`.

Since both headers already have API to load programs, new functions are
added not to break backward compatibility for existing ones:
* `bpf_load_program_xattr()` is added to `bpf/bpf.h`;
* `bpf_prog_load_xattr()` is added to `bpf/libbpf.h`.

Both new functions accept structures, `struct bpf_load_program_attr` and
`struct bpf_prog_load_attr` correspondingly, where new fields can be
added in the future w/o changing the API.

Standard `_xattr` suffix is used to name the new API functions.

Since `bpf_load_program_name()` is not used as heavily as
`bpf_load_program()`, it was removed in favor of more generic
`bpf_load_program_xattr()`.

Signed-off-by: default avatarAndrey Ignatov <rdna@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 5e43f899

tools/include/uapi/linux/bpf.h

+5 −0
Original line number Diff line number Diff line
@@ -296,6 +296,11 @@ union bpf_attr { 
		__u32		prog_flags;

		char		prog_name[BPF_OBJ_NAME_LEN];

		__u32		prog_ifindex;	/* ifindex of netdev to prep for */

		/* For some prog types expected attach type must be known at

		 * load time to verify attach type specific parts of prog

		 * (context accesses, allowed helpers, etc).

		 */

		__u32		expected_attach_type;

	};



	struct { /* anonymous struct used by BPF_OBJ_* commands */

tools/lib/bpf/bpf.c

+29 −15
Original line number Diff line number Diff line
@@ -146,26 +146,30 @@ int bpf_create_map_in_map(enum bpf_map_type map_type, const char *name, 
					  -1);

}



int bpf_load_program_name(enum bpf_prog_type type, const char *name,

			  const struct bpf_insn *insns,

			  size_t insns_cnt, const char *license,

			  __u32 kern_version, char *log_buf,

			  size_t log_buf_sz)

int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,

			   char *log_buf, size_t log_buf_sz)

{

	int fd;

	union bpf_attr attr;

	__u32 name_len = name ? strlen(name) : 0;

	__u32 name_len;

	int fd;



	if (!load_attr)

		return -EINVAL;



	name_len = load_attr->name ? strlen(load_attr->name) : 0;



	bzero(&attr, sizeof(attr));

	attr.prog_type = type;

	attr.insn_cnt = (__u32)insns_cnt;

	attr.insns = ptr_to_u64(insns);

	attr.license = ptr_to_u64(license);

	attr.prog_type = load_attr->prog_type;

	attr.expected_attach_type = load_attr->expected_attach_type;

	attr.insn_cnt = (__u32)load_attr->insns_cnt;

	attr.insns = ptr_to_u64(load_attr->insns);

	attr.license = ptr_to_u64(load_attr->license);

	attr.log_buf = ptr_to_u64(NULL);

	attr.log_size = 0;

	attr.log_level = 0;

	attr.kern_version = kern_version;

	memcpy(attr.prog_name, name, min(name_len, BPF_OBJ_NAME_LEN - 1));

	attr.kern_version = load_attr->kern_version;

	memcpy(attr.prog_name, load_attr->name,

	       min(name_len, BPF_OBJ_NAME_LEN - 1));



	fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));

	if (fd >= 0 || !log_buf || !log_buf_sz)
@@ -184,8 +188,18 @@ int bpf_load_program(enum bpf_prog_type type, const struct bpf_insn *insns, 
		     __u32 kern_version, char *log_buf,

		     size_t log_buf_sz)

{

	return bpf_load_program_name(type, NULL, insns, insns_cnt, license,

				     kern_version, log_buf, log_buf_sz);

	struct bpf_load_program_attr load_attr;



	memset(&load_attr, 0, sizeof(struct bpf_load_program_attr));

	load_attr.prog_type = type;

	load_attr.expected_attach_type = 0;

	load_attr.name = NULL;

	load_attr.insns = insns;

	load_attr.insns_cnt = insns_cnt;

	load_attr.license = license;

	load_attr.kern_version = kern_version;



	return bpf_load_program_xattr(&load_attr, log_buf, log_buf_sz);

}



int bpf_verify_program(enum bpf_prog_type type, const struct bpf_insn *insns,

tools/lib/bpf/bpf.h

+12 −5
Original line number Diff line number Diff line
@@ -41,13 +41,20 @@ int bpf_create_map_in_map(enum bpf_map_type map_type, const char *name, 
			  int key_size, int inner_map_fd, int max_entries,

			  __u32 map_flags);



struct bpf_load_program_attr {

	enum bpf_prog_type prog_type;

	enum bpf_attach_type expected_attach_type;

	const char *name;

	const struct bpf_insn *insns;

	size_t insns_cnt;

	const char *license;

	__u32 kern_version;

};



/* Recommend log buffer size */

#define BPF_LOG_BUF_SIZE (256 * 1024)

int bpf_load_program_name(enum bpf_prog_type type, const char *name,

			  const struct bpf_insn *insns,

			  size_t insns_cnt, const char *license,

			  __u32 kern_version, char *log_buf,

			  size_t log_buf_sz);

int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,

			   char *log_buf, size_t log_buf_sz);

int bpf_load_program(enum bpf_prog_type type, const struct bpf_insn *insns,

		     size_t insns_cnt, const char *license,

		     __u32 kern_version, char *log_buf,

tools/lib/bpf/libbpf.c

+79 −26
Original line number Diff line number Diff line
@@ -203,6 +203,8 @@ struct bpf_program { 
	struct bpf_object *obj;

	void *priv;

	bpf_program_clear_priv_t clear_priv;



	enum bpf_attach_type expected_attach_type;

};



struct bpf_map {
@@ -1162,21 +1164,31 @@ static int bpf_object__collect_reloc(struct bpf_object *obj) 
}



static int

load_program(enum bpf_prog_type type, const char *name, struct bpf_insn *insns,

	     int insns_cnt, char *license, u32 kern_version, int *pfd)

load_program(enum bpf_prog_type type, enum bpf_attach_type expected_attach_type,

	     const char *name, struct bpf_insn *insns, int insns_cnt,

	     char *license, u32 kern_version, int *pfd)

{

	int ret;

	struct bpf_load_program_attr load_attr;

	char *log_buf;

	int ret;



	if (!insns || !insns_cnt)

	memset(&load_attr, 0, sizeof(struct bpf_load_program_attr));

	load_attr.prog_type = type;

	load_attr.expected_attach_type = expected_attach_type;

	load_attr.name = name;

	load_attr.insns = insns;

	load_attr.insns_cnt = insns_cnt;

	load_attr.license = license;

	load_attr.kern_version = kern_version;



	if (!load_attr.insns || !load_attr.insns_cnt)

		return -EINVAL;



	log_buf = malloc(BPF_LOG_BUF_SIZE);

	if (!log_buf)

		pr_warning("Alloc log buffer for bpf loader error, continue without log\n");



	ret = bpf_load_program_name(type, name, insns, insns_cnt, license,

				    kern_version, log_buf, BPF_LOG_BUF_SIZE);

	ret = bpf_load_program_xattr(&load_attr, log_buf, BPF_LOG_BUF_SIZE);



	if (ret >= 0) {

		*pfd = ret;
@@ -1192,18 +1204,18 @@ load_program(enum bpf_prog_type type, const char *name, struct bpf_insn *insns, 
		pr_warning("-- BEGIN DUMP LOG ---\n");

		pr_warning("\n%s\n", log_buf);

		pr_warning("-- END LOG --\n");

	} else if (insns_cnt >= BPF_MAXINSNS) {

		pr_warning("Program too large (%d insns), at most %d insns\n",

			   insns_cnt, BPF_MAXINSNS);

	} else if (load_attr.insns_cnt >= BPF_MAXINSNS) {

		pr_warning("Program too large (%zu insns), at most %d insns\n",

			   load_attr.insns_cnt, BPF_MAXINSNS);

		ret = -LIBBPF_ERRNO__PROG2BIG;

	} else {

		/* Wrong program type? */

		if (type != BPF_PROG_TYPE_KPROBE) {

		if (load_attr.prog_type != BPF_PROG_TYPE_KPROBE) {

			int fd;



			fd = bpf_load_program_name(BPF_PROG_TYPE_KPROBE, name,

						   insns, insns_cnt, license,

						   kern_version, NULL, 0);

			load_attr.prog_type = BPF_PROG_TYPE_KPROBE;

			load_attr.expected_attach_type = 0;

			fd = bpf_load_program_xattr(&load_attr, NULL, 0);

			if (fd >= 0) {

				close(fd);

				ret = -LIBBPF_ERRNO__PROGTYPE;
@@ -1247,8 +1259,9 @@ bpf_program__load(struct bpf_program *prog, 
			pr_warning("Program '%s' is inconsistent: nr(%d) != 1\n",

				   prog->section_name, prog->instances.nr);

		}

		err = load_program(prog->type, prog->name, prog->insns,

				   prog->insns_cnt, license, kern_version, &fd);

		err = load_program(prog->type, prog->expected_attach_type,

				   prog->name, prog->insns, prog->insns_cnt,

				   license, kern_version, &fd);

		if (!err)

			prog->instances.fds[0] = fd;

		goto out;
@@ -1276,8 +1289,8 @@ bpf_program__load(struct bpf_program *prog, 
			continue;

		}



		err = load_program(prog->type, prog->name,

				   result.new_insn_ptr,

		err = load_program(prog->type, prog->expected_attach_type,

				   prog->name, result.new_insn_ptr,

				   result.new_insn_cnt,

				   license, kern_version, &fd);
@@ -1835,11 +1848,22 @@ BPF_PROG_TYPE_FNS(tracepoint, BPF_PROG_TYPE_TRACEPOINT); 
BPF_PROG_TYPE_FNS(xdp, BPF_PROG_TYPE_XDP);

BPF_PROG_TYPE_FNS(perf_event, BPF_PROG_TYPE_PERF_EVENT);



#define BPF_PROG_SEC(string, type) { string, sizeof(string) - 1, type }

static void bpf_program__set_expected_attach_type(struct bpf_program *prog,

						 enum bpf_attach_type type)

{

	prog->expected_attach_type = type;

}



#define BPF_PROG_SEC_FULL(string, ptype, atype) \

	{ string, sizeof(string) - 1, ptype, atype }



#define BPF_PROG_SEC(string, ptype) BPF_PROG_SEC_FULL(string, ptype, 0)



static const struct {

	const char *sec;

	size_t len;

	enum bpf_prog_type prog_type;

	enum bpf_attach_type expected_attach_type;

} section_names[] = {

	BPF_PROG_SEC("socket",		BPF_PROG_TYPE_SOCKET_FILTER),

	BPF_PROG_SEC("kprobe/",		BPF_PROG_TYPE_KPROBE),
@@ -1859,9 +1883,11 @@ static const struct { 
	BPF_PROG_SEC("sk_skb",		BPF_PROG_TYPE_SK_SKB),

	BPF_PROG_SEC("sk_msg",		BPF_PROG_TYPE_SK_MSG),

};



#undef BPF_PROG_SEC

#undef BPF_PROG_SEC_FULL



static enum bpf_prog_type bpf_program__guess_type(struct bpf_program *prog)

static int bpf_program__identify_section(struct bpf_program *prog)

{

	int i;
@@ -1871,13 +1897,13 @@ static enum bpf_prog_type bpf_program__guess_type(struct bpf_program *prog) 
	for (i = 0; i < ARRAY_SIZE(section_names); i++)

		if (strncmp(prog->section_name, section_names[i].sec,

			    section_names[i].len) == 0)

			return section_names[i].prog_type;

			return i;



err:

	pr_warning("failed to guess program type based on section name %s\n",

		   prog->section_name);



	return BPF_PROG_TYPE_UNSPEC;

	return -1;

}



int bpf_map__fd(struct bpf_map *map)
@@ -1976,12 +2002,31 @@ long libbpf_get_error(const void *ptr) 


int bpf_prog_load(const char *file, enum bpf_prog_type type,

		  struct bpf_object **pobj, int *prog_fd)

{

	struct bpf_prog_load_attr attr;



	memset(&attr, 0, sizeof(struct bpf_prog_load_attr));

	attr.file = file;

	attr.prog_type = type;

	attr.expected_attach_type = 0;



	return bpf_prog_load_xattr(&attr, pobj, prog_fd);

}



int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,

			struct bpf_object **pobj, int *prog_fd)

{

	struct bpf_program *prog, *first_prog = NULL;

	enum bpf_attach_type expected_attach_type;

	enum bpf_prog_type prog_type;

	struct bpf_object *obj;

	int section_idx;

	int err;



	obj = bpf_object__open(file);

	if (!attr)

		return -EINVAL;



	obj = bpf_object__open(attr->file);

	if (IS_ERR(obj))

		return -ENOENT;
@@ -1990,15 +2035,23 @@ int bpf_prog_load(const char *file, enum bpf_prog_type type, 
		 * If type is not specified, try to guess it based on

		 * section name.

		 */

		if (type == BPF_PROG_TYPE_UNSPEC) {

			type = bpf_program__guess_type(prog);

			if (type == BPF_PROG_TYPE_UNSPEC) {

		prog_type = attr->prog_type;

		expected_attach_type = attr->expected_attach_type;

		if (prog_type == BPF_PROG_TYPE_UNSPEC) {

			section_idx = bpf_program__identify_section(prog);

			if (section_idx < 0) {

				bpf_object__close(obj);

				return -EINVAL;

			}

			prog_type = section_names[section_idx].prog_type;

			expected_attach_type =

				section_names[section_idx].expected_attach_type;

		}



		bpf_program__set_type(prog, type);

		bpf_program__set_type(prog, prog_type);

		bpf_program__set_expected_attach_type(prog,

						      expected_attach_type);



		if (prog->idx != obj->efile.text_shndx && !first_prog)

			first_prog = prog;

	}

tools/lib/bpf/libbpf.h

+8 −0
Original line number Diff line number Diff line
@@ -248,6 +248,14 @@ int bpf_map__pin(struct bpf_map *map, const char *path); 


long libbpf_get_error(const void *ptr);



struct bpf_prog_load_attr {

	const char *file;

	enum bpf_prog_type prog_type;

	enum bpf_attach_type expected_attach_type;

};



int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,

			struct bpf_object **pobj, int *prog_fd);

int bpf_prog_load(const char *file, enum bpf_prog_type type,

		  struct bpf_object **pobj, int *prog_fd);