| Message ID | 20201201044104.24948-2-andreimatei1@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | libbpf: fail early when loading programs with unspecified type | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for bpf-next |
| netdev/subject_prefix | success | Link |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | warning | CHECK: Alignment should match open parenthesis WARNING: line length of 105 exceeds 80 columns WARNING: line length of 112 exceeds 80 columns WARNING: line length of 82 exceeds 80 columns WARNING: please, no spaces at the start of a line |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
| netdev/stable | success | Stable not CCed |
On Mon, Nov 30, 2020 at 8:43 PM Andrei Matei <andreimatei1@gmail.com> wrote: > > Before this patch, a program with unspecified type > (BPF_PROG_TYPE_UNSPEC) would be passed to the BPF syscall, only to have > the kernel reject it with an opaque invalid argument error. This patch > makes libbpf reject such programs with a nicer error message - in > particular libbpf now tries to diagnose bad ELF section names at both > open time and load time. > > Signed-off-by: Andrei Matei <andreimatei1@gmail.com> > --- This is useful, thanks. See below for a few comments, though. > tools/lib/bpf/libbpf.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index 313034117070..abca93b4f239 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -6629,6 +6629,18 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, > char *log_buf = NULL; > int btf_fd, ret; > > + if (prog->type == BPF_PROG_TYPE_UNSPEC) { > + if (!prog->sec_def) { > + // We couldn't find a proper section definition at load time; that's probably why > + // the program type is missing. no C++-style comments, please > + pr_warn("prog '%s': missing BPF prog type'; check ELF section name '%s'\n", extra ' after "prog type"? also ';' -> ',' ? > + prog->name, prog->sec_name); > + } else { > + pr_warn("prog '%s': missing BPF prog type\n", prog->name); while, technically, user can manually set program type to UNSPEC even with good section name, that's probably extreme case which we shouldn't worry about. So I'd just always emit the section name. > + } > + return -EINVAL; > + } > + > if (!insns || !insns_cnt) > return -EINVAL; > > @@ -6920,9 +6932,11 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, > > bpf_object__for_each_program(prog, obj) { > prog->sec_def = find_sec_def(prog->sec_name); > - if (!prog->sec_def) > + if (!prog->sec_def) { > /* couldn't guess, but user might manually specify */ > + pr_debug("prog '%s': unrecognized ELF section name '%s'\n", prog->name, prog->sec_name); > continue; > + } > > if (prog->sec_def->is_sleepable) > prog->prog_flags |= BPF_F_SLEEPABLE; > -- > 2.27.0 >
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 313034117070..abca93b4f239 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -6629,6 +6629,18 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, char *log_buf = NULL; int btf_fd, ret; + if (prog->type == BPF_PROG_TYPE_UNSPEC) { + if (!prog->sec_def) { + // We couldn't find a proper section definition at load time; that's probably why + // the program type is missing. + pr_warn("prog '%s': missing BPF prog type'; check ELF section name '%s'\n", + prog->name, prog->sec_name); + } else { + pr_warn("prog '%s': missing BPF prog type\n", prog->name); + } + return -EINVAL; + } + if (!insns || !insns_cnt) return -EINVAL; @@ -6920,9 +6932,11 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, bpf_object__for_each_program(prog, obj) { prog->sec_def = find_sec_def(prog->sec_name); - if (!prog->sec_def) + if (!prog->sec_def) { /* couldn't guess, but user might manually specify */ + pr_debug("prog '%s': unrecognized ELF section name '%s'\n", prog->name, prog->sec_name); continue; + } if (prog->sec_def->is_sleepable) prog->prog_flags |= BPF_F_SLEEPABLE;
Before this patch, a program with unspecified type (BPF_PROG_TYPE_UNSPEC) would be passed to the BPF syscall, only to have the kernel reject it with an opaque invalid argument error. This patch makes libbpf reject such programs with a nicer error message - in particular libbpf now tries to diagnose bad ELF section names at both open time and load time. Signed-off-by: Andrei Matei <andreimatei1@gmail.com> --- tools/lib/bpf/libbpf.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)