From: Andrii Nakryiko <andriin@fb.com>
Date: Fri, 13 Dec 2019 17:43:25 -0800
Subject: libbpf: Don't require root for bpf_object__open()
Patch-mainline: v5.6-rc1
Git-commit: 0d13bfce023ac7cef4d0a50b83750254ce31c479
References: bsc#1177028
Reorganize bpf_object__open and bpf_object__load steps such that
bpf_object__open doesn't need root access. This was previously done for
feature probing and BTF sanitization. This doesn't have to happen on open,
though, so move all those steps into the load phase.
This is important, because it makes it possible for tools like bpftool, to
just open BPF object file and inspect their contents: programs, maps, BTF,
etc. For such operations it is prohibitive to require root access. On the
other hand, there is a lot of custom libbpf logic in those steps, so its best
avoided for tools to reimplement all that on their own.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191214014341.3442258-2-andriin@fb.com
Acked-by: Gary Lin <glin@suse.com>
---
tools/lib/bpf/libbpf.c | 83 ++++++++++++++++++++++++-------------------------
1 file changed, 41 insertions(+), 42 deletions(-)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -101,13 +101,6 @@ void libbpf_print(enum libbpf_print_leve
#define STRERR_BUFSIZE 128
-#define CHECK_ERR(action, err, out) do { \
- err = action; \
- if (err) \
- goto out; \
-} while (0)
-
-
/* Copied from tools/perf/util/util.h */
#ifndef zfree
# define zfree(ptr) ({ free(*ptr); *ptr = NULL; })
@@ -864,8 +857,7 @@ bpf_object__init_internal_map(struct bpf
def->value_size = data->d_size;
def->max_entries = 1;
def->map_flags = type == LIBBPF_MAP_RODATA ? BPF_F_RDONLY_PROG : 0;
- if (obj->caps.array_mmap)
- def->map_flags |= BPF_F_MMAPABLE;
+ def->map_flags |= BPF_F_MMAPABLE;
pr_debug("map '%s' (global data): at sec_idx %d, offset %zu, flags %x.\n",
map_name, map->sec_idx, map->sec_offset, def->map_flags);
@@ -888,8 +880,6 @@ static int bpf_object__init_global_data_
{
int err;
- if (!obj->caps.global_data)
- return 0;
/*
* Populate obj->maps with libbpf internal maps.
*/
@@ -1394,10 +1384,11 @@ static int bpf_object__init_user_btf_map
return 0;
}
-static int bpf_object__init_maps(struct bpf_object *obj, bool relaxed_maps,
- const char *pin_root_path)
+static int bpf_object__init_maps(struct bpf_object *obj,
+ struct bpf_object_open_opts *opts)
{
- bool strict = !relaxed_maps;
+ const char *pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
+ bool strict = !OPTS_GET(opts, relaxed_maps, false);
int err;
err = bpf_object__init_user_maps(obj, strict);
@@ -1594,8 +1585,7 @@ static int bpf_object__sanitize_and_load
return 0;
}
-static int bpf_object__elf_collect(struct bpf_object *obj, bool relaxed_maps,
- const char *pin_root_path)
+static int bpf_object__elf_collect(struct bpf_object *obj)
{
Elf *elf = obj->efile.elf;
GElf_Ehdr *ep = &obj->efile.ehdr;
@@ -1730,14 +1720,7 @@ static int bpf_object__elf_collect(struc
pr_warning("Corrupted ELF file: index of strtab invalid\n");
return -LIBBPF_ERRNO__FORMAT;
}
- err = bpf_object__init_btf(obj, btf_data, btf_ext_data);
- if (!err)
- err = bpf_object__init_maps(obj, relaxed_maps, pin_root_path);
- if (!err)
- err = bpf_object__sanitize_and_load_btf(obj);
- if (!err)
- err = bpf_object__init_prog_names(obj);
- return err;
+ return bpf_object__init_btf(obj, btf_data, btf_ext_data);
}
static struct bpf_program *
@@ -1878,11 +1861,6 @@ static int bpf_program__record_reloc(str
pr_warning("bad data relo against section %u\n", shdr_idx);
return -LIBBPF_ERRNO__RELOC;
}
- if (!obj->caps.global_data) {
- pr_warning("relocation: kernel does not support global \'%s\' variable access in insns[%d]\n",
- name, insn_idx);
- return -LIBBPF_ERRNO__RELOC;
- }
for (map_idx = 0; map_idx < nr_maps; map_idx++) {
map = &obj->maps[map_idx];
if (map->libbpf_type != type)
@@ -3927,12 +3905,10 @@ static struct bpf_object *
__bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
struct bpf_object_open_opts *opts)
{
- const char *pin_root_path;
struct bpf_program *prog;
struct bpf_object *obj;
const char *obj_name;
char tmp_name[64];
- bool relaxed_maps;
__u32 attach_prog_fd;
int err;
@@ -3962,16 +3938,16 @@ __bpf_object__open(const char *path, con
return obj;
obj->relaxed_core_relocs = OPTS_GET(opts, relaxed_core_relocs, false);
- relaxed_maps = OPTS_GET(opts, relaxed_maps, false);
- pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
attach_prog_fd = OPTS_GET(opts, attach_prog_fd, 0);
- CHECK_ERR(bpf_object__elf_init(obj), err, out);
- CHECK_ERR(bpf_object__check_endianness(obj), err, out);
- CHECK_ERR(bpf_object__probe_caps(obj), err, out);
- CHECK_ERR(bpf_object__elf_collect(obj, relaxed_maps, pin_root_path),
- err, out);
- CHECK_ERR(bpf_object__collect_reloc(obj), err, out);
+ err = bpf_object__elf_init(obj);
+ err = err ? : bpf_object__check_endianness(obj);
+ err = err ? : bpf_object__elf_collect(obj);
+ err = err ? : bpf_object__init_maps(obj, opts);
+ err = err ? : bpf_object__init_prog_names(obj);
+ err = err ? : bpf_object__collect_reloc(obj);
+ if (err)
+ goto out;
bpf_object__elf_finish(obj);
bpf_object__for_each_program(prog, obj) {
@@ -4089,6 +4065,24 @@ int bpf_object__unload(struct bpf_object
return 0;
}
+static int bpf_object__sanitize_maps(struct bpf_object *obj)
+{
+ struct bpf_map *m;
+
+ bpf_object__for_each_map(m, obj) {
+ if (!bpf_map__is_internal(m))
+ continue;
+ if (!obj->caps.global_data) {
+ pr_warning("kernel doesn't support global data\n");
+ return -ENOTSUP;
+ }
+ if (!obj->caps.array_mmap)
+ m->def.map_flags ^= BPF_F_MMAPABLE;
+ }
+
+ return 0;
+}
+
int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
{
struct bpf_object *obj;
@@ -4107,9 +4101,14 @@ int bpf_object__load_xattr(struct bpf_ob
obj->loaded = true;
- CHECK_ERR(bpf_object__create_maps(obj), err, out);
- CHECK_ERR(bpf_object__relocate(obj, attr->target_btf_path), err, out);
- CHECK_ERR(bpf_object__load_progs(obj, attr->log_level), err, out);
+ err = bpf_object__probe_caps(obj);
+ err = err ? : bpf_object__sanitize_and_load_btf(obj);
+ err = err ? : bpf_object__sanitize_maps(obj);
+ err = err ? : bpf_object__create_maps(obj);
+ err = err ? : bpf_object__relocate(obj, attr->target_btf_path);
+ err = err ? : bpf_object__load_progs(obj, attr->log_level);
+ if (err)
+ goto out;
return 0;
out: