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[96.239.57.246]) by smtp.gmail.com with ESMTPSA id l79sm703445qke.1.2020.11.30.20.41.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 Nov 2020 20:41:38 -0800 (PST) From: Andrei Matei To: bpf@vger.kernel.org Cc: Andrei Matei Subject: [PATCH bpf-next 1/1] libbpf: fail early when loading programs with unspecified type Date: Mon, 30 Nov 2020 23:41:04 -0500 Message-Id: <20201201044104.24948-2-andreimatei1@gmail.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20201201044104.24948-1-andreimatei1@gmail.com> References: <20201201044104.24948-1-andreimatei1@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net 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 --- 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. + 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;