Merge branch 'libbpf: add unified bpf_prog_load() low-level API'

Andrii Nakryiko says:

====================

This patch set adds unified OPTS-based low-level bpf_prog_load() API for
loading BPF programs directly into kernel without utilizing libbpf's
bpf_object abstractions. This OPTS-based interface allows for future
extensions without breaking backwards or forward API and ABI compatibility.
Similar approach will be used for other low-level APIs that require extensive
sets of parameters, like BPF_MAP_CREATE command.

First half of the patch set adds libbpf API, cleans up internal usage of
to-be-deprecated APIs, etc. Second half cleans up and converts selftests away
from using deprecated APIs. See individual patches for more details.

v1->v2:
  - dropped exposing sys_bpf() into public API (Alexei, Daniel);
  - also dropped bpftool/cgroup.c fix for unistd.h include because it's not
    necessary due to sys_bpf() staying as is.

Cc: Hengqi Chen <hengqi.chen@gmail.com>
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/bpf/bpftool/feature.c

@@ -467,7 +467,7 @@ static bool probe_bpf_syscall(const char *define_prefix)
 {
 	bool res;
 
-	bpf_load_program(BPF_PROG_TYPE_UNSPEC, NULL, 0, NULL, 0, NULL, 0);
+	bpf_prog_load(BPF_PROG_TYPE_UNSPEC, NULL, NULL, NULL, 0, NULL);
 	res = (errno != ENOSYS);
 
 	print_bool_feature("have_bpf_syscall",

tools/lib/bpf/bpf.c

@@ -28,6 +28,7 @@
 #include <asm/unistd.h>
 #include <errno.h>
 #include <linux/bpf.h>
+#include <limits.h>
 #include "bpf.h"
 #include "libbpf.h"
 #include "libbpf_internal.h"
@@ -74,14 +75,15 @@ static inline int sys_bpf_fd(enum bpf_cmd cmd, union bpf_attr *attr,
 	return ensure_good_fd(fd);
 }
 
-static inline int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size)
+#define PROG_LOAD_ATTEMPTS 5
+
+static inline int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts)
 {
-	int retries = 5;
 	int fd;
 
 	do {
 		fd = sys_bpf_fd(BPF_PROG_LOAD, attr, size);
-	} while (fd < 0 && errno == EAGAIN && retries-- > 0);
+	} while (fd < 0 && errno == EAGAIN && --attempts > 0);
 
 	return fd;
 }
@@ -253,58 +255,91 @@ alloc_zero_tailing_info(const void *orecord, __u32 cnt,
 	return info;
 }
 
-int libbpf__bpf_prog_load(const struct bpf_prog_load_params *load_attr)
+DEFAULT_VERSION(bpf_prog_load_v0_6_0, bpf_prog_load, LIBBPF_0.6.0)
+int bpf_prog_load_v0_6_0(enum bpf_prog_type prog_type,
+		         const char *prog_name, const char *license,
+		         const struct bpf_insn *insns, size_t insn_cnt,
+		         const struct bpf_prog_load_opts *opts)
 {
 	void *finfo = NULL, *linfo = NULL;
+	const char *func_info, *line_info;
+	__u32 log_size, log_level, attach_prog_fd, attach_btf_obj_fd;
+	__u32 func_info_rec_size, line_info_rec_size;
+	int fd, attempts;
 	union bpf_attr attr;
-	int fd;
+	char *log_buf;
 
-	if (!load_attr->log_buf != !load_attr->log_buf_sz)
+	if (!OPTS_VALID(opts, bpf_prog_load_opts))
 		return libbpf_err(-EINVAL);
 
-	if (load_attr->log_level > (4 | 2 | 1) || (load_attr->log_level && !load_attr->log_buf))
+	attempts = OPTS_GET(opts, attempts, 0);
+	if (attempts < 0)
 		return libbpf_err(-EINVAL);
+	if (attempts == 0)
+		attempts = PROG_LOAD_ATTEMPTS;
 
 	memset(&attr, 0, sizeof(attr));
-	attr.prog_type = load_attr->prog_type;
-	attr.expected_attach_type = load_attr->expected_attach_type;
 
-	if (load_attr->attach_prog_fd)
-		attr.attach_prog_fd = load_attr->attach_prog_fd;
-	else
-		attr.attach_btf_obj_fd = load_attr->attach_btf_obj_fd;
-	attr.attach_btf_id = load_attr->attach_btf_id;
+	attr.prog_type = prog_type;
+	attr.expected_attach_type = OPTS_GET(opts, expected_attach_type, 0);
 
-	attr.prog_ifindex = load_attr->prog_ifindex;
-	attr.kern_version = load_attr->kern_version;
+	attr.prog_btf_fd = OPTS_GET(opts, prog_btf_fd, 0);
+	attr.prog_flags = OPTS_GET(opts, prog_flags, 0);
+	attr.prog_ifindex = OPTS_GET(opts, prog_ifindex, 0);
+	attr.kern_version = OPTS_GET(opts, kern_version, 0);
 
-	attr.insn_cnt = (__u32)load_attr->insn_cnt;
-	attr.insns = ptr_to_u64(load_attr->insns);
-	attr.license = ptr_to_u64(load_attr->license);
+	if (prog_name)
+		strncat(attr.prog_name, prog_name, sizeof(attr.prog_name) - 1);
+	attr.license = ptr_to_u64(license);
 
-	attr.log_level = load_attr->log_level;
-	if (attr.log_level) {
-		attr.log_buf = ptr_to_u64(load_attr->log_buf);
-		attr.log_size = load_attr->log_buf_sz;
-	}
+	if (insn_cnt > UINT_MAX)
+		return libbpf_err(-E2BIG);
+
+	attr.insns = ptr_to_u64(insns);
+	attr.insn_cnt = (__u32)insn_cnt;
+
+	attach_prog_fd = OPTS_GET(opts, attach_prog_fd, 0);
+	attach_btf_obj_fd = OPTS_GET(opts, attach_btf_obj_fd, 0);
+
+	if (attach_prog_fd && attach_btf_obj_fd)
+		return libbpf_err(-EINVAL);
+
+	attr.attach_btf_id = OPTS_GET(opts, attach_btf_id, 0);
+	if (attach_prog_fd)
+		attr.attach_prog_fd = attach_prog_fd;
+	else
+		attr.attach_btf_obj_fd = attach_btf_obj_fd;
 
-	attr.prog_btf_fd = load_attr->prog_btf_fd;
-	attr.prog_flags = load_attr->prog_flags;
+	log_buf = OPTS_GET(opts, log_buf, NULL);
+	log_size = OPTS_GET(opts, log_size, 0);
+	log_level = OPTS_GET(opts, log_level, 0);
 
-	attr.func_info_rec_size = load_attr->func_info_rec_size;
-	attr.func_info_cnt = load_attr->func_info_cnt;
-	attr.func_info = ptr_to_u64(load_attr->func_info);
+	if (!!log_buf != !!log_size)
+		return libbpf_err(-EINVAL);
+	if (log_level > (4 | 2 | 1))
+		return libbpf_err(-EINVAL);
+	if (log_level && !log_buf)
+		return libbpf_err(-EINVAL);
 
-	attr.line_info_rec_size = load_attr->line_info_rec_size;
-	attr.line_info_cnt = load_attr->line_info_cnt;
-	attr.line_info = ptr_to_u64(load_attr->line_info);
-	attr.fd_array = ptr_to_u64(load_attr->fd_array);
+	attr.log_level = log_level;
+	attr.log_buf = ptr_to_u64(log_buf);
+	attr.log_size = log_size;
 
-	if (load_attr->name)
-		memcpy(attr.prog_name, load_attr->name,
-		       min(strlen(load_attr->name), (size_t)BPF_OBJ_NAME_LEN - 1));
+	func_info_rec_size = OPTS_GET(opts, func_info_rec_size, 0);
+	func_info = OPTS_GET(opts, func_info, NULL);
+	attr.func_info_rec_size = func_info_rec_size;
+	attr.func_info = ptr_to_u64(func_info);
+	attr.func_info_cnt = OPTS_GET(opts, func_info_cnt, 0);
 
-	fd = sys_bpf_prog_load(&attr, sizeof(attr));
+	line_info_rec_size = OPTS_GET(opts, line_info_rec_size, 0);
+	line_info = OPTS_GET(opts, line_info, NULL);
+	attr.line_info_rec_size = line_info_rec_size;
+	attr.line_info = ptr_to_u64(line_info);
+	attr.line_info_cnt = OPTS_GET(opts, line_info_cnt, 0);
+
+	attr.fd_array = ptr_to_u64(OPTS_GET(opts, fd_array, NULL));
+
+	fd = sys_bpf_prog_load(&attr, sizeof(attr), attempts);
 	if (fd >= 0)
 		return fd;
 
@@ -314,70 +349,72 @@ int libbpf__bpf_prog_load(const struct bpf_prog_load_params *load_attr)
 	 */
 	while (errno == E2BIG && (!finfo || !linfo)) {
 		if (!finfo && attr.func_info_cnt &&
-		    attr.func_info_rec_size < load_attr->func_info_rec_size) {
+		    attr.func_info_rec_size < func_info_rec_size) {
 			/* try with corrected func info records */
-			finfo = alloc_zero_tailing_info(load_attr->func_info,
-							load_attr->func_info_cnt,
-							load_attr->func_info_rec_size,
+			finfo = alloc_zero_tailing_info(func_info,
+							attr.func_info_cnt,
+							func_info_rec_size,
 							attr.func_info_rec_size);
 			if (!finfo) {
 				errno = E2BIG;
 				goto done;
 			}
 
 			attr.func_info = ptr_to_u64(finfo);
-			attr.func_info_rec_size = load_attr->func_info_rec_size;
+			attr.func_info_rec_size = func_info_rec_size;
 		} else if (!linfo && attr.line_info_cnt &&
-			   attr.line_info_rec_size <
-			   load_attr->line_info_rec_size) {
-			linfo = alloc_zero_tailing_info(load_attr->line_info,
-							load_attr->line_info_cnt,
-							load_attr->line_info_rec_size,
+			   attr.line_info_rec_size < line_info_rec_size) {
+			linfo = alloc_zero_tailing_info(line_info,
+							attr.line_info_cnt,
+							line_info_rec_size,
 							attr.line_info_rec_size);
 			if (!linfo) {
 				errno = E2BIG;
 				goto done;
 			}
 
 			attr.line_info = ptr_to_u64(linfo);
-			attr.line_info_rec_size = load_attr->line_info_rec_size;
+			attr.line_info_rec_size = line_info_rec_size;
 		} else {
 			break;
 		}
 
-		fd = sys_bpf_prog_load(&attr, sizeof(attr));
+		fd = sys_bpf_prog_load(&attr, sizeof(attr), attempts);
 		if (fd >= 0)
 			goto done;
 	}
 
-	if (load_attr->log_level || !load_attr->log_buf)
+	if (log_level || !log_buf)
 		goto done;
 
 	/* Try again with log */
-	attr.log_buf = ptr_to_u64(load_attr->log_buf);
-	attr.log_size = load_attr->log_buf_sz;
+	log_buf[0] = 0;
+	attr.log_buf = ptr_to_u64(log_buf);
+	attr.log_size = log_size;
 	attr.log_level = 1;
-	load_attr->log_buf[0] = 0;
 
-	fd = sys_bpf_prog_load(&attr, sizeof(attr));
+	fd = sys_bpf_prog_load(&attr, sizeof(attr), attempts);
 done:
 	/* free() doesn't affect errno, so we don't need to restore it */
 	free(finfo);
 	free(linfo);
 	return libbpf_err_errno(fd);
 }
 
+__attribute__((alias("bpf_load_program_xattr2")))
 int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
-			   char *log_buf, size_t log_buf_sz)
+			   char *log_buf, size_t log_buf_sz);
+
+static int bpf_load_program_xattr2(const struct bpf_load_program_attr *load_attr,
+				   char *log_buf, size_t log_buf_sz)
 {
-	struct bpf_prog_load_params p = {};
+	LIBBPF_OPTS(bpf_prog_load_opts, p);
 
 	if (!load_attr || !log_buf != !log_buf_sz)
 		return libbpf_err(-EINVAL);
 
-	p.prog_type = load_attr->prog_type;
 	p.expected_attach_type = load_attr->expected_attach_type;
-	switch (p.prog_type) {
+	switch (load_attr->prog_type) {
 	case BPF_PROG_TYPE_STRUCT_OPS:
 	case BPF_PROG_TYPE_LSM:
 		p.attach_btf_id = load_attr->attach_btf_id;
@@ -391,23 +428,20 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
 		p.prog_ifindex = load_attr->prog_ifindex;
 		p.kern_version = load_attr->kern_version;
 	}
-	p.insn_cnt = load_attr->insns_cnt;
-	p.insns = load_attr->insns;
-	p.license = load_attr->license;
 	p.log_level = load_attr->log_level;
 	p.log_buf = log_buf;
-	p.log_buf_sz = log_buf_sz;
+	p.log_size = log_buf_sz;
 	p.prog_btf_fd = load_attr->prog_btf_fd;
 	p.func_info_rec_size = load_attr->func_info_rec_size;
 	p.func_info_cnt = load_attr->func_info_cnt;
 	p.func_info = load_attr->func_info;
 	p.line_info_rec_size = load_attr->line_info_rec_size;
 	p.line_info_cnt = load_attr->line_info_cnt;
 	p.line_info = load_attr->line_info;
-	p.name = load_attr->name;
 	p.prog_flags = load_attr->prog_flags;
 
-	return libbpf__bpf_prog_load(&p);
+	return bpf_prog_load(load_attr->prog_type, load_attr->name, load_attr->license,
+			     load_attr->insns, load_attr->insns_cnt, &p);
 }
 
 int bpf_load_program(enum bpf_prog_type type, const struct bpf_insn *insns,
@@ -426,7 +460,7 @@ int bpf_load_program(enum bpf_prog_type type, const struct bpf_insn *insns,
 	load_attr.license = license;
 	load_attr.kern_version = kern_version;
 
-	return bpf_load_program_xattr(&load_attr, log_buf, log_buf_sz);
+	return bpf_load_program_xattr2(&load_attr, log_buf, log_buf_sz);
 }
 
 int bpf_verify_program(enum bpf_prog_type type, const struct bpf_insn *insns,
@@ -449,7 +483,7 @@ int bpf_verify_program(enum bpf_prog_type type, const struct bpf_insn *insns,
 	attr.kern_version = kern_version;
 	attr.prog_flags = prog_flags;
 
-	fd = sys_bpf_prog_load(&attr, sizeof(attr));
+	fd = sys_bpf_prog_load(&attr, sizeof(attr), PROG_LOAD_ATTEMPTS);
 	return libbpf_err_errno(fd);
 }
 

tools/lib/bpf/bpf.h

@@ -29,6 +29,7 @@
 #include <stdint.h>
 
 #include "libbpf_common.h"
+#include "libbpf_legacy.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -71,6 +72,71 @@ LIBBPF_API int bpf_create_map_in_map(enum bpf_map_type map_type,
 				     int inner_map_fd, int max_entries,
 				     __u32 map_flags);
 
+struct bpf_prog_load_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+
+	/* libbpf can retry BPF_PROG_LOAD command if bpf() syscall returns
+	 * -EAGAIN. This field determines how many attempts libbpf has to
+	 *  make. If not specified, libbpf will use default value of 5.
+	 */
+	int attempts;
+
+	enum bpf_attach_type expected_attach_type;
+	__u32 prog_btf_fd;
+	__u32 prog_flags;
+	__u32 prog_ifindex;
+	__u32 kern_version;
+
+	__u32 attach_btf_id;
+	__u32 attach_prog_fd;
+	__u32 attach_btf_obj_fd;
+
+	const int *fd_array;
+
+	/* .BTF.ext func info data */
+	const void *func_info;
+	__u32 func_info_cnt;
+	__u32 func_info_rec_size;
+
+	/* .BTF.ext line info data */
+	const void *line_info;
+	__u32 line_info_cnt;
+	__u32 line_info_rec_size;
+
+	/* verifier log options */
+	__u32 log_level;
+	__u32 log_size;
+	char *log_buf;
+};
+#define bpf_prog_load_opts__last_field log_buf
+
+LIBBPF_API int bpf_prog_load(enum bpf_prog_type prog_type,
+			     const char *prog_name, const char *license,
+			     const struct bpf_insn *insns, size_t insn_cnt,
+			     const struct bpf_prog_load_opts *opts);
+/* this "specialization" should go away in libbpf 1.0 */
+LIBBPF_API int bpf_prog_load_v0_6_0(enum bpf_prog_type prog_type,
+				    const char *prog_name, const char *license,
+				    const struct bpf_insn *insns, size_t insn_cnt,
+				    const struct bpf_prog_load_opts *opts);
+
+/* This is an elaborate way to not conflict with deprecated bpf_prog_load()
+ * API, defined in libbpf.h. Once we hit libbpf 1.0, all this will be gone.
+ * With this approach, if someone is calling bpf_prog_load() with
+ * 4 arguments, they will use the deprecated API, which keeps backwards
+ * compatibility (both source code and binary). If bpf_prog_load() is called
+ * with 6 arguments, though, it gets redirected to __bpf_prog_load.
+ * So looking forward to libbpf 1.0 when this hack will be gone and
+ * __bpf_prog_load() will be called just bpf_prog_load().
+ */
+#ifndef bpf_prog_load
+#define bpf_prog_load(...) ___libbpf_overload(___bpf_prog_load, __VA_ARGS__)
+#define ___bpf_prog_load4(file, type, pobj, prog_fd) \
+	bpf_prog_load_deprecated(file, type, pobj, prog_fd)
+#define ___bpf_prog_load6(prog_type, prog_name, license, insns, insn_cnt, opts) \
+	bpf_prog_load(prog_type, prog_name, license, insns, insn_cnt, opts)
+#endif /* bpf_prog_load */
+
 struct bpf_load_program_attr {
 	enum bpf_prog_type prog_type;
 	enum bpf_attach_type expected_attach_type;
@@ -102,13 +168,15 @@ struct bpf_load_program_attr {
 
 /* Recommend log buffer size */
 #define BPF_LOG_BUF_SIZE (UINT32_MAX >> 8) /* verifier maximum in kernels <= 5.1 */
-LIBBPF_API int
-bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
-		       char *log_buf, size_t log_buf_sz);
+LIBBPF_DEPRECATED_SINCE(0, 7, "use bpf_prog_load() instead")
+LIBBPF_API int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
+				      char *log_buf, size_t log_buf_sz);
+LIBBPF_DEPRECATED_SINCE(0, 7, "use bpf_prog_load() instead")
 LIBBPF_API 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, size_t log_buf_sz);
+LIBBPF_DEPRECATED_SINCE(0, 7, "use bpf_prog_load() instead")
 LIBBPF_API int bpf_verify_program(enum bpf_prog_type type,
 				  const struct bpf_insn *insns,
 				  size_t insns_cnt, __u32 prog_flags,