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Message-Id: <20211110192324.920934-1-sdf@google.com>
Date: Wed, 10 Nov 2021 11:23:24 -0800
From: Stanislav Fomichev <sdf@...gle.com>
To: netdev@...r.kernel.org, bpf@...r.kernel.org
Cc: ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
Stanislav Fomichev <sdf@...gle.com>,
Quentin Monnet <quentin@...valent.com>,
John Fastabend <john.fastabend@...il.com>
Subject: [PATCH bpf-next v2] bpftool: enable libbpf's strict mode by default
Otherwise, attaching with bpftool doesn't work with strict section names.
Also:
- add --legacy option to switch back to pre-1.0 behavior
- print a warning when program fails to load in strict mode to point
to --legacy flag
- by default, don't append / to the section name; in strict
mode it's relevant only for a small subset of prog types
+ bpftool --legacy prog loadall tools/testing/selftests/bpf/test_cgroup_link.o /sys/fs/bpf/kprobe type kprobe
libbpf: failed to pin program: File exists
Error: failed to pin all programs
+ bpftool prog loadall tools/testing/selftests/bpf/test_cgroup_link.o /sys/fs/bpf/kprobe type kprobe
v2:
- strict by default (Quentin Monnet)
- add more info to --legacy description (Quentin Monnet)
- add bash completion (Quentin Monnet)
Cc: Quentin Monnet <quentin@...valent.com>
Cc: John Fastabend <john.fastabend@...il.com>
Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
---
.../bpftool/Documentation/common_options.rst | 9 +++++
tools/bpf/bpftool/bash-completion/bpftool | 2 +-
tools/bpf/bpftool/main.c | 13 +++++-
tools/bpf/bpftool/main.h | 3 +-
tools/bpf/bpftool/prog.c | 40 +++++++++++--------
5 files changed, 48 insertions(+), 19 deletions(-)
diff --git a/tools/bpf/bpftool/Documentation/common_options.rst b/tools/bpf/bpftool/Documentation/common_options.rst
index 05d06c74dcaa..75adf23202d8 100644
--- a/tools/bpf/bpftool/Documentation/common_options.rst
+++ b/tools/bpf/bpftool/Documentation/common_options.rst
@@ -20,3 +20,12 @@
Print all logs available, even debug-level information. This includes
logs from libbpf as well as from the verifier, when attempting to
load programs.
+
+-l, --legacy
+ Use legacy libbpf mode which has more relaxed BPF program
+ requirements. By default, bpftool has more strict requirements
+ about section names, changes pinning logic and doesn't support
+ some of the older non-BTF map declarations.
+
+ See https://github.com/libbpf/libbpf/wiki/Libbpf:-the-road-to-v1.0
+ for details.
diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
index 88e2bcf16cca..4a1b02ff72c1 100644
--- a/tools/bpf/bpftool/bash-completion/bpftool
+++ b/tools/bpf/bpftool/bash-completion/bpftool
@@ -261,7 +261,7 @@ _bpftool()
# Deal with options
if [[ ${words[cword]} == -* ]]; then
local c='--version --json --pretty --bpffs --mapcompat --debug \
- --use-loader --base-btf'
+ --use-loader --base-btf --legacy'
COMPREPLY=( $( compgen -W "$c" -- "$cur" ) )
return 0
fi
diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index 28237d7cef67..473791e87f7d 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -31,6 +31,7 @@ bool block_mount;
bool verifier_logs;
bool relaxed_maps;
bool use_loader;
+bool legacy_libbpf;
struct btf *base_btf;
struct hashmap *refs_table;
@@ -396,6 +397,7 @@ int main(int argc, char **argv)
{ "debug", no_argument, NULL, 'd' },
{ "use-loader", no_argument, NULL, 'L' },
{ "base-btf", required_argument, NULL, 'B' },
+ { "legacy", no_argument, NULL, 'l' },
{ 0 }
};
int opt, ret;
@@ -408,7 +410,7 @@ int main(int argc, char **argv)
bin_name = argv[0];
opterr = 0;
- while ((opt = getopt_long(argc, argv, "VhpjfLmndB:",
+ while ((opt = getopt_long(argc, argv, "VhpjfLmndB:l",
options, NULL)) >= 0) {
switch (opt) {
case 'V':
@@ -454,6 +456,9 @@ int main(int argc, char **argv)
case 'L':
use_loader = true;
break;
+ case 'l':
+ legacy_libbpf = true;
+ break;
default:
p_err("unrecognized option '%s'", argv[optind - 1]);
if (json_output)
@@ -463,6 +468,12 @@ int main(int argc, char **argv)
}
}
+ if (!legacy_libbpf) {
+ ret = libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
+ if (ret)
+ p_err("failed to enable libbpf strict mode: %d", ret);
+ }
+
argc -= optind;
argv += optind;
if (argc < 0)
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 383835c2604d..8d76d937a62b 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -57,7 +57,7 @@ static inline void *u64_to_ptr(__u64 ptr)
#define HELP_SPEC_PROGRAM \
"PROG := { id PROG_ID | pinned FILE | tag PROG_TAG | name PROG_NAME }"
#define HELP_SPEC_OPTIONS \
- "OPTIONS := { {-j|--json} [{-p|--pretty}] | {-d|--debug}"
+ "OPTIONS := { {-j|--json} [{-p|--pretty}] | {-d|--debug} | {-l|--legacy}"
#define HELP_SPEC_MAP \
"MAP := { id MAP_ID | pinned FILE | name MAP_NAME }"
#define HELP_SPEC_LINK \
@@ -90,6 +90,7 @@ extern bool block_mount;
extern bool verifier_logs;
extern bool relaxed_maps;
extern bool use_loader;
+extern bool legacy_libbpf;
extern struct btf *base_btf;
extern struct hashmap *refs_table;
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index dea7a49ec26e..bf85c914f2fa 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -1483,8 +1483,6 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
while (argc) {
if (is_prefix(*argv, "type")) {
- char *type;
-
NEXT_ARG();
if (common_prog_type != BPF_PROG_TYPE_UNSPEC) {
@@ -1494,21 +1492,26 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
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(*argv, &common_prog_type,
+ &expected_attach_type);
+ if (err < 0) {
+ /* Put a '/' at the end of type to appease libbpf */
+ char *type = malloc(strlen(*argv) + 2);
- err = get_prog_type_by_name(type, &common_prog_type,
- &expected_attach_type);
- free(type);
- if (err < 0)
- goto err_free_reuse_maps;
+ if (!type) {
+ p_err("mem alloc failed");
+ goto err_free_reuse_maps;
+ }
+ *type = 0;
+ strcat(type, *argv);
+ strcat(type, "/");
+
+ err = get_prog_type_by_name(type, &common_prog_type,
+ &expected_attach_type);
+ free(type);
+ if (err < 0)
+ goto err_free_reuse_maps;
+ }
NEXT_ARG();
} else if (is_prefix(*argv, "map")) {
@@ -1731,6 +1734,11 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
else
bpf_object__unpin_programs(obj, pinfile);
err_close_obj:
+ if (!legacy_libbpf) {
+ p_info("Warning: bpftool is now running in libbpf strict mode and has more stringent requirements about BPF programs.\n"
+ "If it used to work for this object file but now doesn't, see --legacy option for more details.\n");
+ }
+
bpf_object__close(obj);
err_free_reuse_maps:
for (i = 0; i < old_map_fds; i++)
--
2.34.0.rc0.344.g81b53c2807-goog
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