From patchwork Tue Jul 25 20:41:12 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 13327023 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 145C4C001DF for ; Tue, 25 Jul 2023 20:42:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229705AbjGYUmV (ORCPT ); Tue, 25 Jul 2023 16:42:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40100 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231550AbjGYUmE (ORCPT ); Tue, 25 Jul 2023 16:42:04 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E4C61BC8; Tue, 25 Jul 2023 13:42:02 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 67ACF6187D; Tue, 25 Jul 2023 20:42:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 58D5FC433C7; Tue, 25 Jul 2023 20:41:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1690317720; bh=O/gvRDbAo1+qfKzhqxHNd4QCmaOLg095hAsSaLBvB7A=; h=From:To:Cc:Subject:Date:From; b=U96/uUjVNsF5ZPDGSmjhAi26ndBRdrgmoQUvoxGViq/F45bF6m/0ghSMSUlD3rsyH SuIdyXiKVU3xtfMkbawyJa8Dc7JX2Z8BSukRNX0olo4fK01QMrP13nvgAQyqO6zWrY il9tCMbFbgVhzSawQ6AxivfEkOJYU7/f3RgXs7gomFRGoTOjBnMTUtKjY+GM6hAxxB qLfaHj1zxDlC5z7ghFeTZxLrVaxFbJpuBXH3AG2CYEu2JaK4hBQb91+UCT3sY+S+sw QLF98JAaL1/BD+kNNjXGNc1XKB9nTGw/t65+Rg6+MtGp744za8emZA6qMpelK7Gd40 joGdvGkdGhBBA== From: Arnd Bergmann To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Song Liu , Steven Rostedt , Masami Hiramatsu Cc: Arnd Bergmann , stable@vger.kernel.org, John Fastabend , Martin KaFai Lau , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Kumar Kartikeya Dwivedi , Dave Marchevsky , David Vernet , Kees Cook , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH] [v4] bpf: fix bpf_probe_read_kernel prototype mismatch Date: Tue, 25 Jul 2023 22:41:12 +0200 Message-Id: <20230725204149.3411961-1-arnd@kernel.org> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org From: Arnd Bergmann bpf_probe_read_kernel() has a __weak definition in core.c and another definition with an incompatible prototype in kernel/trace/bpf_trace.c, when CONFIG_BPF_EVENTS is enabled. Since the two are incompatible, there cannot be a shared declaration in a header file, but the lack of a prototype causes a W=1 warning: kernel/bpf/core.c:1638:12: error: no previous prototype for 'bpf_probe_read_kernel' [-Werror=missing-prototypes] On 32-bit architectures, the local prototype u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr) passes arguments in other registers as the one in bpf_trace.c BPF_CALL_3(bpf_probe_read_kernel, void *, dst, u32, size, const void *, unsafe_ptr) which uses 64-bit arguments in pairs of registers. As both versions of the function are fairly simple and only really differ in one line, just move them into a header file as an inline function that does not add any overhead for the bpf_trace.c callers and actually avoids a function call for the other one. Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/ac25cb0f-b804-1649-3afb-1dc6138c2716@iogearbox.net/ Signed-off-by: Arnd Bergmann --- v4: rewrite again to use a shared inline helper v3: clarify changelog text further. v2: rewrite completely to fix the mismatch. --- include/linux/bpf.h | 12 ++++++++++++ kernel/bpf/core.c | 10 ++-------- kernel/trace/bpf_trace.c | 11 ----------- 3 files changed, 14 insertions(+), 19 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index ceaa8c23287fc..abe75063630b8 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2661,6 +2661,18 @@ static inline void bpf_dynptr_set_rdonly(struct bpf_dynptr_kern *ptr) } #endif /* CONFIG_BPF_SYSCALL */ +static __always_inline int +bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr) +{ + int ret = -EFAULT; + + if (IS_ENABLED(CONFIG_BPF_EVENTS)) + ret = copy_from_kernel_nofault(dst, unsafe_ptr, size); + if (unlikely(ret < 0)) + memset(dst, 0, size); + return ret; +} + void __bpf_free_used_btfs(struct bpf_prog_aux *aux, struct btf_mod_pair *used_btfs, u32 len); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index dd70c58c9d3a3..9cdf53bfb8bd3 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1634,12 +1634,6 @@ bool bpf_opcode_in_insntable(u8 code) } #ifndef CONFIG_BPF_JIT_ALWAYS_ON -u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr) -{ - memset(dst, 0, size); - return -EFAULT; -} - /** * ___bpf_prog_run - run eBPF program on a given context * @regs: is the array of MAX_BPF_EXT_REG eBPF pseudo-registers @@ -1930,8 +1924,8 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn) DST = *(SIZE *)(unsigned long) (SRC + insn->off); \ CONT; \ LDX_PROBE_MEM_##SIZEOP: \ - bpf_probe_read_kernel(&DST, sizeof(SIZE), \ - (const void *)(long) (SRC + insn->off)); \ + bpf_probe_read_kernel_common(&DST, sizeof(SIZE), \ + (const void *)(long) (SRC + insn->off)); \ DST = *((SIZE *)&DST); \ CONT; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index c92eb8c6ff08d..83bde2475ae54 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -223,17 +223,6 @@ const struct bpf_func_proto bpf_probe_read_user_str_proto = { .arg3_type = ARG_ANYTHING, }; -static __always_inline int -bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr) -{ - int ret; - - ret = copy_from_kernel_nofault(dst, unsafe_ptr, size); - if (unlikely(ret < 0)) - memset(dst, 0, size); - return ret; -} - BPF_CALL_3(bpf_probe_read_kernel, void *, dst, u32, size, const void *, unsafe_ptr) {