Merge branch 'bpf-bpftool-improved-prog-load'

Jakub Kicinski says:

====================
This series starts with two minor clean ups to test_offload.py
selftest script.

The next 11 patches extend the abilities of bpftool prog load
beyond the simple cgroup use cases.  Three new parameters are
added:

 - type - allows specifying program type, independent of how
   code sections are named;
 - map  - allows reusing existing maps, instead of creating a new
   map on every program load;
 - dev  - offload/binding to a device.

A number of changes to libbpf is required to accomplish the task.
The section - program type logic mapping is exposed.  We should
probably aim to use the libbpf program section naming everywhere.
For reuse of maps we need to allow users to set FD for bpf map
object in libbpf.

Examples

Load program my_xdp.o and pin it as /sys/fs/bpf/my_xdp, for xdp
program type:

$ bpftool prog load my_xdp.o /sys/fs/bpf/my_xdp \
  type xdp

As above but for offload:

$ bpftool prog load my_xdp.o /sys/fs/bpf/my_xdp \
  type xdp \
  dev netdevsim0

Load program my_maps.o, but for the first map reuse map id 17,
and for the map called "other_map" reuse pinned map /sys/fs/bpf/map0:

$ bpftool prog load my_maps.o /sys/fs/bpf/prog \
  map idx 0 id 17 \
  map name other_map pinned /sys/fs/bpf/map0

v3:
 - fix return codes in patch 5;
 - rename libbpf_prog_type_by_string() -> libbpf_prog_type_by_name();
 - fold file path into xattr in patch 8;
 - add patch 10;
 - use dup3() in patch 12;
 - depend on fd value in patch 12;
 - close old fd in patch 12.
v2:
 - add compat for reallocarray().
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/bpf/bpftool/Documentation/bpftool-prog.rst

@@ -24,10 +24,20 @@ MAP COMMANDS
 |	**bpftool** **prog dump xlated** *PROG* [{**file** *FILE* | **opcodes** | **visual**}]
 |	**bpftool** **prog dump jited**  *PROG* [{**file** *FILE* | **opcodes**}]
 |	**bpftool** **prog pin** *PROG* *FILE*
-|	**bpftool** **prog load** *OBJ* *FILE*
+|	**bpftool** **prog load** *OBJ* *FILE* [**type** *TYPE*] [**map** {**idx** *IDX* | **name** *NAME*} *MAP*] [**dev** *NAME*]
 |	**bpftool** **prog help**
 |
+|	*MAP* := { **id** *MAP_ID* | **pinned** *FILE* }
 |	*PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* }
+|	*TYPE* := {
+|		**socket** | **kprobe** | **kretprobe** | **classifier** | **action** |
+|		**tracepoint** | **raw_tracepoint** | **xdp** | **perf_event** | **cgroup/skb** |
+|		**cgroup/sock** | **cgroup/dev** | **lwt_in** | **lwt_out** | **lwt_xmit** |
+|		**lwt_seg6local** | **sockops** | **sk_skb** | **sk_msg** | **lirc_mode2** |
+|		**cgroup/bind4** | **cgroup/bind6** | **cgroup/post_bind4** | **cgroup/post_bind6** |
+|		**cgroup/connect4** | **cgroup/connect6** | **cgroup/sendmsg4** | **cgroup/sendmsg6**
+|	}
+
 
 DESCRIPTION
 ===========
@@ -64,8 +74,19 @@ DESCRIPTION
 
 		  Note: *FILE* must be located in *bpffs* mount.
 
-	**bpftool prog load** *OBJ* *FILE*
+	**bpftool prog load** *OBJ* *FILE* [**type** *TYPE*] [**map** {**idx** *IDX* | **name** *NAME*} *MAP*] [**dev** *NAME*]
 		  Load bpf program from binary *OBJ* and pin as *FILE*.
+		  **type** is optional, if not specified program type will be
+		  inferred from section names.
+		  By default bpftool will create new maps as declared in the ELF
+		  object being loaded.  **map** parameter allows for the reuse
+		  of existing maps.  It can be specified multiple times, each
+		  time for a different map.  *IDX* refers to index of the map
+		  to be replaced in the ELF file counting from 0, while *NAME*
+		  allows to replace a map by name.  *MAP* specifies the map to
+		  use, referring to it by **id** or through a **pinned** file.
+		  If **dev** *NAME* is specified program will be loaded onto
+		  given networking device (offload).
 
 		  Note: *FILE* must be located in *bpffs* mount.
 
@@ -159,6 +180,14 @@ EXAMPLES
     mov    %rbx,0x0(%rbp)
     48 89 5d 00
 
+|
+| **# bpftool prog load xdp1_kern.o /sys/fs/bpf/xdp1 type xdp map name rxcnt id 7**
+| **# bpftool prog show pinned /sys/fs/bpf/xdp1**
+|   9: xdp  name xdp_prog1  tag 539ec6ce11b52f98  gpl
+|	loaded_at 2018-06-25T16:17:31-0700  uid 0
+|	xlated 488B  jited 336B  memlock 4096B  map_ids 7
+| **# rm /sys/fs/bpf/xdp1**
+|
 
 SEE ALSO
 ========

tools/bpf/bpftool/Makefile

@@ -52,7 +52,7 @@ INSTALL ?= install
 RM ?= rm -f
 
 FEATURE_USER = .bpftool
-FEATURE_TESTS = libbfd disassembler-four-args
+FEATURE_TESTS = libbfd disassembler-four-args reallocarray
 FEATURE_DISPLAY = libbfd disassembler-four-args
 
 check_feat := 1
@@ -75,6 +75,10 @@ ifeq ($(feature-disassembler-four-args), 1)
 CFLAGS += -DDISASM_FOUR_ARGS_SIGNATURE
 endif
 
+ifeq ($(feature-reallocarray), 0)
+CFLAGS += -DCOMPAT_NEED_REALLOCARRAY
+endif
+
 include $(wildcard $(OUTPUT)*.d)
 
 all: $(OUTPUT)bpftool

tools/bpf/bpftool/bash-completion/bpftool

@@ -99,6 +99,35 @@ _bpftool_get_prog_tags()
         command sed -n 's/.*"tag": "\(.*\)",$/\1/p' )" -- "$cur" ) )
 }
 
+_bpftool_get_obj_map_names()
+{
+    local obj
+
+    obj=$1
+
+    maps=$(objdump -j maps -t $obj 2>/dev/null | \
+        command awk '/g     . maps/ {print $NF}')
+
+    COMPREPLY+=( $( compgen -W "$maps" -- "$cur" ) )
+}
+
+_bpftool_get_obj_map_idxs()
+{
+    local obj
+
+    obj=$1
+
+    nmaps=$(objdump -j maps -t $obj 2>/dev/null | grep -c 'g     . maps')
+
+    COMPREPLY+=( $( compgen -W "$(seq 0 $((nmaps - 1)))" -- "$cur" ) )
+}
+
+_sysfs_get_netdevs()
+{
+    COMPREPLY+=( $( compgen -W "$( ls /sys/class/net 2>/dev/null )" -- \
+        "$cur" ) )
+}
+
 # For bpftool map update: retrieve type of the map to update.
 _bpftool_map_update_map_type()
 {
@@ -214,12 +243,14 @@ _bpftool()
     # Completion depends on object and command in use
     case $object in
         prog)
-            case $prev in
-                id)
-                    _bpftool_get_prog_ids
-                    return 0
-                    ;;
-            esac
+            if [[ $command != "load" ]]; then
+                case $prev in
+                    id)
+                        _bpftool_get_prog_ids
+                        return 0
+                        ;;
+                esac
+            fi
 
             local PROG_TYPE='id pinned tag'
             case $command in
@@ -262,8 +293,57 @@ _bpftool()
                     return 0
                     ;;
                 load)
-                    _filedir
-                    return 0
+                    local obj
+
+                    if [[ ${#words[@]} -lt 6 ]]; then
+                        _filedir
+                        return 0
+                    fi
+
+                    obj=${words[3]}
+
+                    if [[ ${words[-4]} == "map" ]]; then
+                        COMPREPLY=( $( compgen -W "id pinned" -- "$cur" ) )
+                        return 0
+                    fi
+                    if [[ ${words[-3]} == "map" ]]; then
+                        if [[ ${words[-2]} == "idx" ]]; then
+                            _bpftool_get_obj_map_idxs $obj
+                        elif [[ ${words[-2]} == "name" ]]; then
+                            _bpftool_get_obj_map_names $obj
+                        fi
+                        return 0
+                    fi
+                    if [[ ${words[-2]} == "map" ]]; then
+                        COMPREPLY=( $( compgen -W "idx name" -- "$cur" ) )
+                        return 0
+                    fi
+
+                    case $prev in
+                        type)
+                            COMPREPLY=( $( compgen -W "socket kprobe kretprobe classifier action tracepoint raw_tracepoint xdp perf_event cgroup/skb cgroup/sock cgroup/dev lwt_in lwt_out lwt_xmit lwt_seg6local sockops sk_skb sk_msg lirc_mode2 cgroup/bind4 cgroup/bind6 cgroup/connect4 cgroup/connect6 cgroup/sendmsg4 cgroup/sendmsg6 cgroup/post_bind4 cgroup/post_bind6" -- \
+                                                   "$cur" ) )
+                            return 0
+                            ;;
+                        id)
+                            _bpftool_get_map_ids
+                            return 0
+                            ;;
+                        pinned)
+                            _filedir
+                            return 0
+                            ;;
+                        dev)
+                            _sysfs_get_netdevs
+                            return 0
+                            ;;
+                        *)
+                            COMPREPLY=( $( compgen -W "map" -- "$cur" ) )
+                            _bpftool_once_attr 'type'
+                            _bpftool_once_attr 'dev'
+                            return 0
+                            ;;
+                    esac
                     ;;
                 *)
                     [[ $prev == $object ]] && \

tools/bpf/bpftool/main.h

@@ -42,6 +42,7 @@
 #include <linux/compiler.h>
 #include <linux/kernel.h>
 #include <linux/hashtable.h>
+#include <tools/libc_compat.h>
 
 #include "json_writer.h"
 
@@ -50,6 +51,21 @@
 #define NEXT_ARG()	({ argc--; argv++; if (argc < 0) usage(); })
 #define NEXT_ARGP()	({ (*argc)--; (*argv)++; if (*argc < 0) usage(); })
 #define BAD_ARG()	({ p_err("what is '%s'?", *argv); -1; })
+#define GET_ARG()	({ argc--; *argv++; })
+#define REQ_ARGS(cnt)							\
+	({								\
+		int _cnt = (cnt);					\
+		bool _res;						\
+									\
+		if (argc < _cnt) {					\
+			p_err("'%s' needs at least %d arguments, %d found", \
+			      argv[-1], _cnt, argc);			\
+			_res = false;					\
+		} else {						\
+			_res = true;					\
+		}							\
+		_res;							\
+	})
 
 #define ERR_MAX_LEN	1024
 
@@ -59,6 +75,8 @@
 	"PROG := { id PROG_ID | pinned FILE | tag PROG_TAG }"
 #define HELP_SPEC_OPTIONS						\
 	"OPTIONS := { {-j|--json} [{-p|--pretty}] | {-f|--bpffs} }"
+#define HELP_SPEC_MAP							\
+	"MAP := { id MAP_ID | pinned FILE }"
 
 enum bpf_obj_type {
 	BPF_OBJ_UNKNOWN,
@@ -120,6 +138,7 @@ int do_cgroup(int argc, char **arg);
 int do_perf(int argc, char **arg);
 
 int prog_parse_fd(int *argc, char ***argv);
+int map_parse_fd(int *argc, char ***argv);
 int map_parse_fd_and_info(int *argc, char ***argv, void *info, __u32 *info_len);
 
 void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,

tools/bpf/bpftool/map.c

@@ -93,7 +93,7 @@ static void *alloc_value(struct bpf_map_info *info)
 		return malloc(info->value_size);
 }
 
-static int map_parse_fd(int *argc, char ***argv)
+int map_parse_fd(int *argc, char ***argv)
 {
 	int fd;
 
@@ -824,7 +824,7 @@ static int do_help(int argc, char **argv)
 		"       %s %s event_pipe MAP [cpu N index M]\n"
 		"       %s %s help\n"
 		"\n"
-		"       MAP := { id MAP_ID | pinned FILE }\n"
+		"       " HELP_SPEC_MAP "\n"
 		"       DATA := { [hex] BYTES }\n"
 		"       " HELP_SPEC_PROGRAM "\n"
 		"       VALUE := { DATA | MAP | PROG }\n"

tools/bpf/bpftool/prog.c

@@ -31,6 +31,7 @@
  * SOFTWARE.
  */
 
+#define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <stdarg.h>
@@ -39,9 +40,12 @@
 #include <string.h>
 #include <time.h>
 #include <unistd.h>
+#include <net/if.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 
+#include <linux/err.h>
+
 #include <bpf.h>
 #include <libbpf.h>
 
@@ -679,31 +683,247 @@ static int do_pin(int argc, char **argv)
 	return err;
 }
 
+struct map_replace {
+	int idx;
+	int fd;
+	char *name;
+};
+
+int map_replace_compar(const void *p1, const void *p2)
+{
+	const struct map_replace *a = p1, *b = p2;
+
+	return a->idx - b->idx;
+}
+
 static int do_load(int argc, char **argv)
 {
+	enum bpf_attach_type expected_attach_type;
+	struct bpf_object_open_attr attr = {
+		.prog_type	= BPF_PROG_TYPE_UNSPEC,
+	};
+	struct map_replace *map_replace = NULL;
+	unsigned int old_map_fds = 0;
+	struct bpf_program *prog;
 	struct bpf_object *obj;
-	int prog_fd;
-
-	if (argc != 2)
-		usage();
+	struct bpf_map *map;
+	const char *pinfile;
+	unsigned int i, j;
+	__u32 ifindex = 0;
+	int idx, err;
 
-	if (bpf_prog_load(argv[0], BPF_PROG_TYPE_UNSPEC, &obj, &prog_fd)) {
-		p_err("failed to load program");
+	if (!REQ_ARGS(2))
 		return -1;
+	attr.file = GET_ARG();
+	pinfile = GET_ARG();
+
+	while (argc) {
+		if (is_prefix(*argv, "type")) {
+			char *type;
+
+			NEXT_ARG();
+
+			if (attr.prog_type != BPF_PROG_TYPE_UNSPEC) {
+				p_err("program type already specified");
+				goto err_free_reuse_maps;
+			}
+			if (!REQ_ARGS(1))
+				goto err_free_reuse_maps;
+
+			/* Put a '/' at the end of type to appease libbpf */
+			type = malloc(strlen(*argv) + 2);
+			if (!type) {
+				p_err("mem alloc failed");
+				goto err_free_reuse_maps;
+			}
+			*type = 0;
+			strcat(type, *argv);
+			strcat(type, "/");
+
+			err = libbpf_prog_type_by_name(type, &attr.prog_type,
+						       &expected_attach_type);
+			free(type);
+			if (err < 0) {
+				p_err("unknown program type '%s'", *argv);
+				goto err_free_reuse_maps;
+			}
+			NEXT_ARG();
+		} else if (is_prefix(*argv, "map")) {
+			char *endptr, *name;
+			int fd;
+
+			NEXT_ARG();
+
+			if (!REQ_ARGS(4))
+				goto err_free_reuse_maps;
+
+			if (is_prefix(*argv, "idx")) {
+				NEXT_ARG();
+
+				idx = strtoul(*argv, &endptr, 0);
+				if (*endptr) {
+					p_err("can't parse %s as IDX", *argv);
+					goto err_free_reuse_maps;
+				}
+				name = NULL;
+			} else if (is_prefix(*argv, "name")) {
+				NEXT_ARG();
+
+				name = *argv;
+				idx = -1;
+			} else {
+				p_err("expected 'idx' or 'name', got: '%s'?",
+				      *argv);
+				goto err_free_reuse_maps;
+			}
+			NEXT_ARG();
+
+			fd = map_parse_fd(&argc, &argv);
+			if (fd < 0)
+				goto err_free_reuse_maps;
+
+			map_replace = reallocarray(map_replace, old_map_fds + 1,
+						   sizeof(*map_replace));
+			if (!map_replace) {
+				p_err("mem alloc failed");
+				goto err_free_reuse_maps;
+			}
+			map_replace[old_map_fds].idx = idx;
+			map_replace[old_map_fds].name = name;
+			map_replace[old_map_fds].fd = fd;
+			old_map_fds++;
+		} else if (is_prefix(*argv, "dev")) {
+			NEXT_ARG();
+
+			if (ifindex) {
+				p_err("offload device already specified");
+				goto err_free_reuse_maps;
+			}
+			if (!REQ_ARGS(1))
+				goto err_free_reuse_maps;
+
+			ifindex = if_nametoindex(*argv);
+			if (!ifindex) {
+				p_err("unrecognized netdevice '%s': %s",
+				      *argv, strerror(errno));
+				goto err_free_reuse_maps;
+			}
+			NEXT_ARG();
+		} else {
+			p_err("expected no more arguments, 'type', 'map' or 'dev', got: '%s'?",
+			      *argv);
+			goto err_free_reuse_maps;
+		}
+	}
+
+	obj = bpf_object__open_xattr(&attr);
+	if (IS_ERR_OR_NULL(obj)) {
+		p_err("failed to open object file");
+		goto err_free_reuse_maps;
+	}
+
+	prog = bpf_program__next(NULL, obj);
+	if (!prog) {
+		p_err("object file doesn't contain any bpf program");
+		goto err_close_obj;
+	}
+
+	bpf_program__set_ifindex(prog, ifindex);
+	if (attr.prog_type == BPF_PROG_TYPE_UNSPEC) {
+		const char *sec_name = bpf_program__title(prog, false);
+
+		err = libbpf_prog_type_by_name(sec_name, &attr.prog_type,
+					       &expected_attach_type);
+		if (err < 0) {
+			p_err("failed to guess program type based on section name %s\n",
+			      sec_name);
+			goto err_close_obj;
+		}
+	}
+	bpf_program__set_type(prog, attr.prog_type);
+	bpf_program__set_expected_attach_type(prog, expected_attach_type);
+
+	qsort(map_replace, old_map_fds, sizeof(*map_replace),
+	      map_replace_compar);
+
+	/* After the sort maps by name will be first on the list, because they
+	 * have idx == -1.  Resolve them.
+	 */
+	j = 0;
+	while (j < old_map_fds && map_replace[j].name) {
+		i = 0;
+		bpf_map__for_each(map, obj) {
+			if (!strcmp(bpf_map__name(map), map_replace[j].name)) {
+				map_replace[j].idx = i;
+				break;
+			}
+			i++;
+		}
+		if (map_replace[j].idx == -1) {
+			p_err("unable to find map '%s'", map_replace[j].name);
+			goto err_close_obj;
+		}
+		j++;
+	}
+	/* Resort if any names were resolved */
+	if (j)
+		qsort(map_replace, old_map_fds, sizeof(*map_replace),
+		      map_replace_compar);
+
+	/* Set ifindex and name reuse */
+	j = 0;
+	idx = 0;
+	bpf_map__for_each(map, obj) {
+		if (!bpf_map__is_offload_neutral(map))
+			bpf_map__set_ifindex(map, ifindex);
+
+		if (j < old_map_fds && idx == map_replace[j].idx) {
+			err = bpf_map__reuse_fd(map, map_replace[j++].fd);
+			if (err) {
+				p_err("unable to set up map reuse: %d", err);
+				goto err_close_obj;
+			}
+
+			/* Next reuse wants to apply to the same map */
+			if (j < old_map_fds && map_replace[j].idx == idx) {
+				p_err("replacement for map idx %d specified more than once",
+				      idx);
+				goto err_close_obj;
+			}
+		}
+
+		idx++;
+	}
+	if (j < old_map_fds) {
+		p_err("map idx '%d' not used", map_replace[j].idx);
+		goto err_close_obj;
+	}
+
+	err = bpf_object__load(obj);
+	if (err) {
+		p_err("failed to load object file");
+		goto err_close_obj;
 	}
 
-	if (do_pin_fd(prog_fd, argv[1]))
+	if (do_pin_fd(bpf_program__fd(prog), pinfile))
 		goto err_close_obj;
 
 	if (json_output)
 		jsonw_null(json_wtr);
 
 	bpf_object__close(obj);
+	for (i = 0; i < old_map_fds; i++)
+		close(map_replace[i].fd);
+	free(map_replace);
 
 	return 0;
 
 err_close_obj:
 	bpf_object__close(obj);
+err_free_reuse_maps:
+	for (i = 0; i < old_map_fds; i++)
+		close(map_replace[i].fd);
+	free(map_replace);
 	return -1;
 }
 
@@ -719,10 +939,19 @@ static int do_help(int argc, char **argv)
 		"       %s %s dump xlated PROG [{ file FILE | opcodes | visual }]\n"
 		"       %s %s dump jited  PROG [{ file FILE | opcodes }]\n"
 		"       %s %s pin   PROG FILE\n"
-		"       %s %s load  OBJ  FILE\n"
+		"       %s %s load  OBJ  FILE [type TYPE] [dev NAME] \\\n"
+		"                         [map { idx IDX | name NAME } MAP]\n"
 		"       %s %s help\n"
 		"\n"
+		"       " HELP_SPEC_MAP "\n"
 		"       " HELP_SPEC_PROGRAM "\n"
+		"       TYPE := { socket | kprobe | kretprobe | classifier | action |\n"
+		"                 tracepoint | raw_tracepoint | xdp | perf_event | cgroup/skb |\n"
+		"                 cgroup/sock | cgroup/dev | lwt_in | lwt_out | lwt_xmit |\n"
+		"                 lwt_seg6local | sockops | sk_skb | sk_msg | lirc_mode2 |\n"
+		"                 cgroup/bind4 | cgroup/bind6 | cgroup/post_bind4 |\n"
+		"                 cgroup/post_bind6 | cgroup/connect4 | cgroup/connect6 |\n"
+		"                 cgroup/sendmsg4 | cgroup/sendmsg6 }\n"
 		"       " HELP_SPEC_OPTIONS "\n"
 		"",
 		bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2],

tools/bpf/bpftool/xlated_dumper.c

@@ -35,6 +35,7 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
+#define _GNU_SOURCE
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -66,9 +67,8 @@ void kernel_syms_load(struct dump_data *dd)
 	while (!feof(fp)) {
 		if (!fgets(buff, sizeof(buff), fp))
 			break;
-		tmp = realloc(dd->sym_mapping,
-			      (dd->sym_count + 1) *
-			      sizeof(*dd->sym_mapping));
+		tmp = reallocarray(dd->sym_mapping, dd->sym_count + 1,
+				   sizeof(*dd->sym_mapping));
 		if (!tmp) {
 out:
 			free(dd->sym_mapping);

tools/build/feature/Makefile

@@ -14,6 +14,7 @@ FILES=                                          \
          test-libaudit.bin                      \
          test-libbfd.bin                        \
          test-disassembler-four-args.bin        \
+         test-reallocarray.bin			\
          test-liberty.bin                       \
          test-liberty-z.bin                     \
          test-cplus-demangle.bin                \
@@ -204,6 +205,9 @@ $(OUTPUT)test-libbfd.bin:
 $(OUTPUT)test-disassembler-four-args.bin:
 	$(BUILD) -DPACKAGE='"perf"' -lbfd -lopcodes
 
+$(OUTPUT)test-reallocarray.bin:
+	$(BUILD)
+
 $(OUTPUT)test-liberty.bin:
 	$(CC) $(CFLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty
 

tools/build/feature/test-reallocarray.c

+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <stdlib.h>
+
+int main(void)
+{
+	return !!reallocarray(NULL, 1, 1);
+}

tools/include/linux/compiler-gcc.h

@@ -36,3 +36,7 @@
 #endif
 #define __printf(a, b)	__attribute__((format(printf, a, b)))
 #define __scanf(a, b)	__attribute__((format(scanf, a, b)))
+
+#if GCC_VERSION >= 50100
+#define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
+#endif

tools/include/linux/overflow.h

+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+#ifndef __LINUX_OVERFLOW_H
+#define __LINUX_OVERFLOW_H
+
+#include <linux/compiler.h>
+
+/*
+ * In the fallback code below, we need to compute the minimum and
+ * maximum values representable in a given type. These macros may also
+ * be useful elsewhere, so we provide them outside the
+ * COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW block.
+ *
+ * It would seem more obvious to do something like
+ *
+ * #define type_min(T) (T)(is_signed_type(T) ? (T)1 << (8*sizeof(T)-1) : 0)
+ * #define type_max(T) (T)(is_signed_type(T) ? ((T)1 << (8*sizeof(T)-1)) - 1 : ~(T)0)
+ *
+ * Unfortunately, the middle expressions, strictly speaking, have
+ * undefined behaviour, and at least some versions of gcc warn about
+ * the type_max expression (but not if -fsanitize=undefined is in
+ * effect; in that case, the warning is deferred to runtime...).
+ *
+ * The slightly excessive casting in type_min is to make sure the
+ * macros also produce sensible values for the exotic type _Bool. [The
+ * overflow checkers only almost work for _Bool, but that's
+ * a-feature-not-a-bug, since people shouldn't be doing arithmetic on
+ * _Bools. Besides, the gcc builtins don't allow _Bool* as third
+ * argument.]
+ *
+ * Idea stolen from
+ * https://mail-index.netbsd.org/tech-misc/2007/02/05/0000.html -
+ * credit to Christian Biere.
+ */
+#define is_signed_type(type)       (((type)(-1)) < (type)1)
+#define __type_half_max(type) ((type)1 << (8*sizeof(type) - 1 - is_signed_type(type)))
+#define type_max(T) ((T)((__type_half_max(T) - 1) + __type_half_max(T)))
+#define type_min(T) ((T)((T)-type_max(T)-(T)1))
+
+
+#ifdef COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW
+/*
+ * For simplicity and code hygiene, the fallback code below insists on
+ * a, b and *d having the same type (similar to the min() and max()
+ * macros), whereas gcc's type-generic overflow checkers accept
+ * different types. Hence we don't just make check_add_overflow an
+ * alias for __builtin_add_overflow, but add type checks similar to
+ * below.
+ */
+#define check_add_overflow(a, b, d) ({		\
+	typeof(a) __a = (a);			\
+	typeof(b) __b = (b);			\
+	typeof(d) __d = (d);			\
+	(void) (&__a == &__b);			\
+	(void) (&__a == __d);			\
+	__builtin_add_overflow(__a, __b, __d);	\
+})
+
+#define check_sub_overflow(a, b, d) ({		\
+	typeof(a) __a = (a);			\
+	typeof(b) __b = (b);			\
+	typeof(d) __d = (d);			\
+	(void) (&__a == &__b);			\
+	(void) (&__a == __d);			\
+	__builtin_sub_overflow(__a, __b, __d);	\
+})
+
+#define check_mul_overflow(a, b, d) ({		\
+	typeof(a) __a = (a);			\
+	typeof(b) __b = (b);			\
+	typeof(d) __d = (d);			\
+	(void) (&__a == &__b);			\
+	(void) (&__a == __d);			\
+	__builtin_mul_overflow(__a, __b, __d);	\
+})
+
+#else
+
+
+/* Checking for unsigned overflow is relatively easy without causing UB. */
+#define __unsigned_add_overflow(a, b, d) ({	\
+	typeof(a) __a = (a);			\
+	typeof(b) __b = (b);			\
+	typeof(d) __d = (d);			\
+	(void) (&__a == &__b);			\
+	(void) (&__a == __d);			\
+	*__d = __a + __b;			\
+	*__d < __a;				\
+})
+#define __unsigned_sub_overflow(a, b, d) ({	\
+	typeof(a) __a = (a);			\
+	typeof(b) __b = (b);			\
+	typeof(d) __d = (d);			\
+	(void) (&__a == &__b);			\
+	(void) (&__a == __d);			\
+	*__d = __a - __b;			\
+	__a < __b;				\
+})
+/*
+ * If one of a or b is a compile-time constant, this avoids a division.
+ */
+#define __unsigned_mul_overflow(a, b, d) ({		\
+	typeof(a) __a = (a);				\
+	typeof(b) __b = (b);				\
+	typeof(d) __d = (d);				\
+	(void) (&__a == &__b);				\
+	(void) (&__a == __d);				\
+	*__d = __a * __b;				\
+	__builtin_constant_p(__b) ?			\
+	  __b > 0 && __a > type_max(typeof(__a)) / __b : \
+	  __a > 0 && __b > type_max(typeof(__b)) / __a;	 \
+})
+
+/*
+ * For signed types, detecting overflow is much harder, especially if
+ * we want to avoid UB. But the interface of these macros is such that
+ * we must provide a result in *d, and in fact we must produce the
+ * result promised by gcc's builtins, which is simply the possibly
+ * wrapped-around value. Fortunately, we can just formally do the
+ * operations in the widest relevant unsigned type (u64) and then
+ * truncate the result - gcc is smart enough to generate the same code
+ * with and without the (u64) casts.
+ */
+
+/*
+ * Adding two signed integers can overflow only if they have the same
+ * sign, and overflow has happened iff the result has the opposite
+ * sign.
+ */
+#define __signed_add_overflow(a, b, d) ({	\
+	typeof(a) __a = (a);			\
+	typeof(b) __b = (b);			\
+	typeof(d) __d = (d);			\
+	(void) (&__a == &__b);			\
+	(void) (&__a == __d);			\
+	*__d = (u64)__a + (u64)__b;		\
+	(((~(__a ^ __b)) & (*__d ^ __a))	\
+		& type_min(typeof(__a))) != 0;	\
+})
+
+/*
+ * Subtraction is similar, except that overflow can now happen only
+ * when the signs are opposite. In this case, overflow has happened if
+ * the result has the opposite sign of a.
+ */
+#define __signed_sub_overflow(a, b, d) ({	\
+	typeof(a) __a = (a);			\
+	typeof(b) __b = (b);			\
+	typeof(d) __d = (d);			\
+	(void) (&__a == &__b);			\
+	(void) (&__a == __d);			\
+	*__d = (u64)__a - (u64)__b;		\
+	((((__a ^ __b)) & (*__d ^ __a))		\
+		& type_min(typeof(__a))) != 0;	\
+})
+
+/*
+ * Signed multiplication is rather hard. gcc always follows C99, so
+ * division is truncated towards 0. This means that we can write the
+ * overflow check like this:
+ *
+ * (a > 0 && (b > MAX/a || b < MIN/a)) ||
+ * (a < -1 && (b > MIN/a || b < MAX/a) ||
+ * (a == -1 && b == MIN)
+ *
+ * The redundant casts of -1 are to silence an annoying -Wtype-limits
+ * (included in -Wextra) warning: When the type is u8 or u16, the
+ * __b_c_e in check_mul_overflow obviously selects
+ * __unsigned_mul_overflow, but unfortunately gcc still parses this
+ * code and warns about the limited range of __b.
+ */
+
+#define __signed_mul_overflow(a, b, d) ({				\
+	typeof(a) __a = (a);						\
+	typeof(b) __b = (b);						\
+	typeof(d) __d = (d);						\
+	typeof(a) __tmax = type_max(typeof(a));				\
+	typeof(a) __tmin = type_min(typeof(a));				\
+	(void) (&__a == &__b);						\
+	(void) (&__a == __d);						\
+	*__d = (u64)__a * (u64)__b;					\
+	(__b > 0   && (__a > __tmax/__b || __a < __tmin/__b)) ||	\
+	(__b < (typeof(__b))-1  && (__a > __tmin/__b || __a < __tmax/__b)) || \
+	(__b == (typeof(__b))-1 && __a == __tmin);			\
+})
+
+
+#define check_add_overflow(a, b, d)					\
+	__builtin_choose_expr(is_signed_type(typeof(a)),		\
+			__signed_add_overflow(a, b, d),			\
+			__unsigned_add_overflow(a, b, d))
+
+#define check_sub_overflow(a, b, d)					\
+	__builtin_choose_expr(is_signed_type(typeof(a)),		\
+			__signed_sub_overflow(a, b, d),			\
+			__unsigned_sub_overflow(a, b, d))
+
+#define check_mul_overflow(a, b, d)					\
+	__builtin_choose_expr(is_signed_type(typeof(a)),		\
+			__signed_mul_overflow(a, b, d),			\
+			__unsigned_mul_overflow(a, b, d))
+
+
+#endif /* COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW */
+
+/**
+ * array_size() - Calculate size of 2-dimensional array.
+ *
+ * @a: dimension one
+ * @b: dimension two
+ *
+ * Calculates size of 2-dimensional array: @a * @b.
+ *
+ * Returns: number of bytes needed to represent the array or SIZE_MAX on
+ * overflow.
+ */
+static inline __must_check size_t array_size(size_t a, size_t b)
+{
+	size_t bytes;
+
+	if (check_mul_overflow(a, b, &bytes))
+		return SIZE_MAX;
+
+	return bytes;
+}
+
+/**
+ * array3_size() - Calculate size of 3-dimensional array.
+ *
+ * @a: dimension one
+ * @b: dimension two
+ * @c: dimension three
+ *
+ * Calculates size of 3-dimensional array: @a * @b * @c.
+ *
+ * Returns: number of bytes needed to represent the array or SIZE_MAX on
+ * overflow.
+ */
+static inline __must_check size_t array3_size(size_t a, size_t b, size_t c)
+{
+	size_t bytes;
+
+	if (check_mul_overflow(a, b, &bytes))
+		return SIZE_MAX;
+	if (check_mul_overflow(bytes, c, &bytes))
+		return SIZE_MAX;
+
+	return bytes;
+}
+
+static inline __must_check size_t __ab_c_size(size_t n, size_t size, size_t c)
+{
+	size_t bytes;
+
+	if (check_mul_overflow(n, size, &bytes))
+		return SIZE_MAX;
+	if (check_add_overflow(bytes, c, &bytes))
+		return SIZE_MAX;
+
+	return bytes;
+}
+
+/**
+ * struct_size() - Calculate size of structure with trailing array.
+ * @p: Pointer to the structure.
+ * @member: Name of the array member.
+ * @n: Number of elements in the array.
+ *
+ * Calculates size of memory needed for structure @p followed by an
+ * array of @n @member elements.
+ *
+ * Return: number of bytes needed or SIZE_MAX on overflow.
+ */
+#define struct_size(p, member, n)					\
+	__ab_c_size(n,							\
+		    sizeof(*(p)->member) + __must_be_array((p)->member),\
+		    sizeof(*(p)))
+
+#endif /* __LINUX_OVERFLOW_H */

tools/include/tools/libc_compat.h

+// SPDX-License-Identifier: GPL-2.0+
+/* Copyright (C) 2018 Netronome Systems, Inc. */
+
+#ifndef __TOOLS_LIBC_COMPAT_H
+#define __TOOLS_LIBC_COMPAT_H
+
+#include <stdlib.h>
+#include <linux/overflow.h>
+
+#ifdef COMPAT_NEED_REALLOCARRAY
+static inline void *reallocarray(void *ptr, size_t nmemb, size_t size)
+{
+	size_t bytes;
+
+	if (unlikely(check_mul_overflow(nmemb, size, &bytes)))
+		return NULL;
+	return realloc(ptr, bytes);
+}
+#endif
+#endif

tools/lib/bpf/Build

-libbpf-y := libbpf.o bpf.o nlattr.o btf.o
+libbpf-y := libbpf.o bpf.o nlattr.o btf.o libbpf_errno.o

tools/lib/bpf/Makefile

@@ -66,7 +66,7 @@ ifndef VERBOSE
 endif
 
 FEATURE_USER = .libbpf
-FEATURE_TESTS = libelf libelf-getphdrnum libelf-mmap bpf
+FEATURE_TESTS = libelf libelf-getphdrnum libelf-mmap bpf reallocarray
 FEATURE_DISPLAY = libelf bpf
 
 INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(ARCH)/include/uapi -I$(srctree)/tools/include/uapi -I$(srctree)/tools/perf
@@ -120,6 +120,10 @@ ifeq ($(feature-libelf-getphdrnum), 1)
   override CFLAGS += -DHAVE_ELF_GETPHDRNUM_SUPPORT
 endif
 
+ifeq ($(feature-reallocarray), 0)
+  override CFLAGS += -DCOMPAT_NEED_REALLOCARRAY
+endif
+
 # Append required CFLAGS
 override CFLAGS += $(EXTRA_WARNINGS)
 override CFLAGS += -Werror -Wall

tools/lib/bpf/libbpf.c

@@ -22,6 +22,7 @@
  * License along with this program; if not,  see <http://www.gnu.org/licenses>
  */
 
+#define _GNU_SOURCE
 #include <stdlib.h>
 #include <stdio.h>
 #include <stdarg.h>
@@ -41,6 +42,7 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/vfs.h>
+#include <tools/libc_compat.h>
 #include <libelf.h>
 #include <gelf.h>
 
@@ -95,54 +97,6 @@ void libbpf_set_print(libbpf_print_fn_t warn,
 
 #define STRERR_BUFSIZE  128
 
-#define ERRNO_OFFSET(e)		((e) - __LIBBPF_ERRNO__START)
-#define ERRCODE_OFFSET(c)	ERRNO_OFFSET(LIBBPF_ERRNO__##c)
-#define NR_ERRNO	(__LIBBPF_ERRNO__END - __LIBBPF_ERRNO__START)
-
-static const char *libbpf_strerror_table[NR_ERRNO] = {
-	[ERRCODE_OFFSET(LIBELF)]	= "Something wrong in libelf",
-	[ERRCODE_OFFSET(FORMAT)]	= "BPF object format invalid",
-	[ERRCODE_OFFSET(KVERSION)]	= "'version' section incorrect or lost",
-	[ERRCODE_OFFSET(ENDIAN)]	= "Endian mismatch",
-	[ERRCODE_OFFSET(INTERNAL)]	= "Internal error in libbpf",
-	[ERRCODE_OFFSET(RELOC)]		= "Relocation failed",
-	[ERRCODE_OFFSET(VERIFY)]	= "Kernel verifier blocks program loading",
-	[ERRCODE_OFFSET(PROG2BIG)]	= "Program too big",
-	[ERRCODE_OFFSET(KVER)]		= "Incorrect kernel version",
-	[ERRCODE_OFFSET(PROGTYPE)]	= "Kernel doesn't support this program type",
-	[ERRCODE_OFFSET(WRNGPID)]	= "Wrong pid in netlink message",
-	[ERRCODE_OFFSET(INVSEQ)]	= "Invalid netlink sequence",
-};
-
-int libbpf_strerror(int err, char *buf, size_t size)
-{
-	if (!buf || !size)
-		return -1;
-
-	err = err > 0 ? err : -err;
-
-	if (err < __LIBBPF_ERRNO__START) {
-		int ret;
-
-		ret = strerror_r(err, buf, size);
-		buf[size - 1] = '\0';
-		return ret;
-	}
-
-	if (err < __LIBBPF_ERRNO__END) {
-		const char *msg;
-
-		msg = libbpf_strerror_table[ERRNO_OFFSET(err)];
-		snprintf(buf, size, "%s", msg);
-		buf[size - 1] = '\0';
-		return 0;
-	}
-
-	snprintf(buf, size, "Unknown libbpf error %d", err);
-	buf[size - 1] = '\0';
-	return -1;
-}
-
 #define CHECK_ERR(action, err, out) do {	\
 	err = action;			\
 	if (err)			\
@@ -369,7 +323,7 @@ bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,
 	progs = obj->programs;
 	nr_progs = obj->nr_programs;
 
-	progs = realloc(progs, sizeof(progs[0]) * (nr_progs + 1));
+	progs = reallocarray(progs, nr_progs + 1, sizeof(progs[0]));
 	if (!progs) {
 		/*
 		 * In this case the original obj->programs
@@ -870,8 +824,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 				continue;
 			}
 
-			reloc = realloc(reloc,
-					sizeof(*obj->efile.reloc) * nr_reloc);
+			reloc = reallocarray(reloc, nr_reloc,
+					     sizeof(*obj->efile.reloc));
 			if (!reloc) {
 				pr_warning("realloc failed\n");
 				err = -ENOMEM;
@@ -1081,6 +1035,53 @@ static int bpf_map_find_btf_info(struct bpf_map *map, const struct btf *btf)
 	return 0;
 }
 
+int bpf_map__reuse_fd(struct bpf_map *map, int fd)
+{
+	struct bpf_map_info info = {};
+	__u32 len = sizeof(info);
+	int new_fd, err;
+	char *new_name;
+
+	err = bpf_obj_get_info_by_fd(fd, &info, &len);
+	if (err)
+		return err;
+
+	new_name = strdup(info.name);
+	if (!new_name)
+		return -errno;
+
+	new_fd = open("/", O_RDONLY | O_CLOEXEC);
+	if (new_fd < 0)
+		goto err_free_new_name;
+
+	new_fd = dup3(fd, new_fd, O_CLOEXEC);
+	if (new_fd < 0)
+		goto err_close_new_fd;
+
+	err = zclose(map->fd);
+	if (err)
+		goto err_close_new_fd;
+	free(map->name);
+
+	map->fd = new_fd;
+	map->name = new_name;
+	map->def.type = info.type;
+	map->def.key_size = info.key_size;
+	map->def.value_size = info.value_size;
+	map->def.max_entries = info.max_entries;
+	map->def.map_flags = info.map_flags;
+	map->btf_key_type_id = info.btf_key_type_id;
+	map->btf_value_type_id = info.btf_value_type_id;
+
+	return 0;
+
+err_close_new_fd:
+	close(new_fd);
+err_free_new_name:
+	free(new_name);
+	return -errno;
+}
+
 static int
 bpf_object__create_maps(struct bpf_object *obj)
 {
@@ -1093,6 +1094,12 @@ bpf_object__create_maps(struct bpf_object *obj)
 		struct bpf_map_def *def = &map->def;
 		int *pfd = &map->fd;
 
+		if (map->fd >= 0) {
+			pr_debug("skip map create (preset) %s: fd=%d\n",
+				 map->name, map->fd);
+			continue;
+		}
+
 		create_attr.name = map->name;
 		create_attr.map_ifindex = map->map_ifindex;
 		create_attr.map_type = def->type;
@@ -1163,7 +1170,7 @@ bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj,
 			return -LIBBPF_ERRNO__RELOC;
 		}
 		new_cnt = prog->insns_cnt + text->insns_cnt;
-		new_insn = realloc(prog->insns, new_cnt * sizeof(*insn));
+		new_insn = reallocarray(prog->insns, new_cnt, sizeof(*insn));
 		if (!new_insn) {
 			pr_warning("oom in prog realloc\n");
 			return -ENOMEM;
@@ -1520,15 +1527,26 @@ __bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz,
 	return ERR_PTR(err);
 }
 
-struct bpf_object *bpf_object__open(const char *path)
+struct bpf_object *bpf_object__open_xattr(struct bpf_object_open_attr *attr)
 {
 	/* param validation */
-	if (!path)
+	if (!attr->file)
 		return NULL;
 
-	pr_debug("loading %s\n", path);
+	pr_debug("loading %s\n", attr->file);
+
+	return __bpf_object__open(attr->file, NULL, 0,
+				  bpf_prog_type__needs_kver(attr->prog_type));
+}
+
+struct bpf_object *bpf_object__open(const char *path)
+{
+	struct bpf_object_open_attr attr = {
+		.file		= path,
+		.prog_type	= BPF_PROG_TYPE_UNSPEC,
+	};
 
-	return __bpf_object__open(path, NULL, 0, true);
+	return bpf_object__open_xattr(&attr);
 }
 
 struct bpf_object *bpf_object__open_buffer(void *obj_buf,
@@ -2081,23 +2099,31 @@ static const struct {
 #undef BPF_S_PROG_SEC
 #undef BPF_SA_PROG_SEC
 
-static int bpf_program__identify_section(struct bpf_program *prog)
+int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
+			     enum bpf_attach_type *expected_attach_type)
 {
 	int i;
 
-	if (!prog->section_name)
-		goto err;
-
-	for (i = 0; i < ARRAY_SIZE(section_names); i++)
-		if (strncmp(prog->section_name, section_names[i].sec,
-			    section_names[i].len) == 0)
-			return i;
+	if (!name)
+		return -EINVAL;
 
-err:
-	pr_warning("failed to guess program type based on section name %s\n",
-		   prog->section_name);
+	for (i = 0; i < ARRAY_SIZE(section_names); i++) {
+		if (strncmp(name, section_names[i].sec, section_names[i].len))
+			continue;
+		*prog_type = section_names[i].prog_type;
+		*expected_attach_type = section_names[i].expected_attach_type;
+		return 0;
+	}
+	return -EINVAL;
+}
 
-	return -1;
+static int
+bpf_program__identify_section(struct bpf_program *prog,
+			      enum bpf_prog_type *prog_type,
+			      enum bpf_attach_type *expected_attach_type)
+{
+	return libbpf_prog_type_by_name(prog->section_name, prog_type,
+					expected_attach_type);
 }
 
 int bpf_map__fd(struct bpf_map *map)
@@ -2146,6 +2172,11 @@ void *bpf_map__priv(struct bpf_map *map)
 	return map ? map->priv : ERR_PTR(-EINVAL);
 }
 
+bool bpf_map__is_offload_neutral(struct bpf_map *map)
+{
+	return map->def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY;
+}
+
 void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex)
 {
 	map->map_ifindex = ifindex;
@@ -2225,12 +2256,15 @@ int bpf_prog_load(const char *file, enum bpf_prog_type type,
 int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
 			struct bpf_object **pobj, int *prog_fd)
 {
+	struct bpf_object_open_attr open_attr = {
+		.file		= attr->file,
+		.prog_type	= attr->prog_type,
+	};
 	struct bpf_program *prog, *first_prog = NULL;
 	enum bpf_attach_type expected_attach_type;
 	enum bpf_prog_type prog_type;
 	struct bpf_object *obj;
 	struct bpf_map *map;
-	int section_idx;
 	int err;
 
 	if (!attr)
@@ -2238,8 +2272,7 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
 	if (!attr->file)
 		return -EINVAL;
 
-	obj = __bpf_object__open(attr->file, NULL, 0,
-				 bpf_prog_type__needs_kver(attr->prog_type));
+	obj = bpf_object__open_xattr(&open_attr);
 	if (IS_ERR_OR_NULL(obj))
 		return -ENOENT;
 
@@ -2252,14 +2285,14 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
 		prog->prog_ifindex = attr->ifindex;
 		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) {
+			err = bpf_program__identify_section(prog, &prog_type,
+							    &expected_attach_type);
+			if (err < 0) {
+				pr_warning("failed to guess program type based on section name %s\n",
+					   prog->section_name);
 				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, prog_type);
@@ -2271,7 +2304,8 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
 	}
 
 	bpf_map__for_each(map, obj) {
-		map->map_ifindex = attr->ifindex;
+		if (!bpf_map__is_offload_neutral(map))
+			map->map_ifindex = attr->ifindex;
 	}
 
 	if (!first_prog) {

tools/lib/bpf/libbpf.h

@@ -66,7 +66,13 @@ void libbpf_set_print(libbpf_print_fn_t warn,
 /* Hide internal to user */
 struct bpf_object;
 
+struct bpf_object_open_attr {
+	const char *file;
+	enum bpf_prog_type prog_type;
+};
+
 struct bpf_object *bpf_object__open(const char *path);
+struct bpf_object *bpf_object__open_xattr(struct bpf_object_open_attr *attr);
 struct bpf_object *bpf_object__open_buffer(void *obj_buf,
 					   size_t obj_buf_sz,
 					   const char *name);
@@ -92,6 +98,9 @@ int bpf_object__set_priv(struct bpf_object *obj, void *priv,
 			 bpf_object_clear_priv_t clear_priv);
 void *bpf_object__priv(struct bpf_object *prog);
 
+int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
+			     enum bpf_attach_type *expected_attach_type);
+
 /* Accessors of bpf_program */
 struct bpf_program;
 struct bpf_program *bpf_program__next(struct bpf_program *prog,
@@ -252,6 +261,8 @@ typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *);
 int bpf_map__set_priv(struct bpf_map *map, void *priv,
 		      bpf_map_clear_priv_t clear_priv);
 void *bpf_map__priv(struct bpf_map *map);
+int bpf_map__reuse_fd(struct bpf_map *map, int fd);
+bool bpf_map__is_offload_neutral(struct bpf_map *map);
 void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex);
 int bpf_map__pin(struct bpf_map *map, const char *path);
 

tools/lib/bpf/libbpf_errno.c

+// SPDX-License-Identifier: LGPL-2.1
+
+/*
+ * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
+ * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015 Huawei Inc.
+ * Copyright (C) 2017 Nicira, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License (not later!)
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not,  see <http://www.gnu.org/licenses>
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include "libbpf.h"
+
+#define ERRNO_OFFSET(e)		((e) - __LIBBPF_ERRNO__START)
+#define ERRCODE_OFFSET(c)	ERRNO_OFFSET(LIBBPF_ERRNO__##c)
+#define NR_ERRNO	(__LIBBPF_ERRNO__END - __LIBBPF_ERRNO__START)
+
+static const char *libbpf_strerror_table[NR_ERRNO] = {
+	[ERRCODE_OFFSET(LIBELF)]	= "Something wrong in libelf",
+	[ERRCODE_OFFSET(FORMAT)]	= "BPF object format invalid",
+	[ERRCODE_OFFSET(KVERSION)]	= "'version' section incorrect or lost",
+	[ERRCODE_OFFSET(ENDIAN)]	= "Endian mismatch",
+	[ERRCODE_OFFSET(INTERNAL)]	= "Internal error in libbpf",
+	[ERRCODE_OFFSET(RELOC)]		= "Relocation failed",
+	[ERRCODE_OFFSET(VERIFY)]	= "Kernel verifier blocks program loading",
+	[ERRCODE_OFFSET(PROG2BIG)]	= "Program too big",
+	[ERRCODE_OFFSET(KVER)]		= "Incorrect kernel version",
+	[ERRCODE_OFFSET(PROGTYPE)]	= "Kernel doesn't support this program type",
+	[ERRCODE_OFFSET(WRNGPID)]	= "Wrong pid in netlink message",
+	[ERRCODE_OFFSET(INVSEQ)]	= "Invalid netlink sequence",
+};
+
+int libbpf_strerror(int err, char *buf, size_t size)
+{
+	if (!buf || !size)
+		return -1;
+
+	err = err > 0 ? err : -err;
+
+	if (err < __LIBBPF_ERRNO__START) {
+		int ret;
+
+		ret = strerror_r(err, buf, size);
+		buf[size - 1] = '\0';
+		return ret;
+	}
+
+	if (err < __LIBBPF_ERRNO__END) {
+		const char *msg;
+
+		msg = libbpf_strerror_table[ERRNO_OFFSET(err)];
+		snprintf(buf, size, "%s", msg);
+		buf[size - 1] = '\0';
+		return 0;
+	}
+
+	snprintf(buf, size, "Unknown libbpf error %d", err);
+	buf[size - 1] = '\0';
+	return -1;
+}

tools/testing/selftests/bpf/test_offload.py

@@ -547,11 +547,11 @@ def check_extack(output, reference, args):
     if skip_extack:
         return
     lines = output.split("\n")
-    comp = len(lines) >= 2 and lines[1] == reference
+    comp = len(lines) >= 2 and lines[1] == 'Error: ' + reference
     fail(not comp, "Missing or incorrect netlink extack message")
 
 def check_extack_nsim(output, reference, args):
-    check_extack(output, "Error: netdevsim: " + reference, args)
+    check_extack(output, "netdevsim: " + reference, args)
 
 def check_no_extack(res, needle):
     fail((res[1] + res[2]).count(needle) or (res[1] + res[2]).count("Warning:"),
@@ -654,7 +654,7 @@ try:
     ret, _, err = sim.cls_bpf_add_filter(obj, skip_sw=True,
                                          fail=False, include_stderr=True)
     fail(ret == 0, "TC filter loaded without enabling TC offloads")
-    check_extack(err, "Error: TC offload is disabled on net device.", args)
+    check_extack(err, "TC offload is disabled on net device.", args)
     sim.wait_for_flush()
 
     sim.set_ethtool_tc_offloads(True)
@@ -694,7 +694,7 @@ try:
                                          skip_sw=True,
                                          fail=False, include_stderr=True)
     fail(ret == 0, "Offloaded a filter to chain other than 0")
-    check_extack(err, "Error: Driver supports only offload of chain 0.", args)
+    check_extack(err, "Driver supports only offload of chain 0.", args)
     sim.tc_flush_filters()
 
     start_test("Test TC replace...")
@@ -830,7 +830,7 @@ try:
     check_extack_nsim(err, "program loaded with different flags.", args)
     ret, _, err = sim.unset_xdp("", force=True,
                                 fail=False, include_stderr=True)
-    fail(ret == 0, "Removed program with a bad mode mode")
+    fail(ret == 0, "Removed program with a bad mode")
     check_extack_nsim(err, "program loaded with different flags.", args)
 
     start_test("Test MTU restrictions...")