From mboxrd@z Thu Jan 1 00:00:00 1970 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8456DC7EE29 for ; Mon, 22 May 2023 20:36:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=klKlh2POkI2ezC8368FOCUI+T42XN9C7jUhz6HVHD7M=; b=goGb9yxi7m4i37 MVTfQeQh/6pdMR5KGZhpbBBtuSm5SDwsQ7hcAjek4eHzteRooDqxII0Frntd2LMuuHA8OxZDg3b65 3qwBlJgDgeJ9jmoNJatlRmGhLNrESBipC0fYSHTUHcj4JEwPBcBCiVINuuC6NVHZST26w+b+yLr5S eGAMa6KdwcYClsrI65mrqvB02J+qqqzZGoP89j00f9rdwpEeDx3hkVEarUwFpJmDQeBBn5cbUTBFV TTYVZrQp6xuJUo5YCmbABh6tYvzIVh3Fq580FbicT+fKD3IVcdhibADtCN/5CRXeJKgw3GYtRICyx tIPNfD8eQOBtgAYbJ1dw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q1CFs-007vxJ-2o; Mon, 22 May 2023 20:35:44 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1q1CFp-007vvR-0f for linux-arm-kernel@lists.infradead.org; Mon, 22 May 2023 20:35:42 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id AB48162BD2; Mon, 22 May 2023 20:35:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 05A3CC4339B; Mon, 22 May 2023 20:35:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1684787740; bh=hPFjOzuSnoN/PTZCIZOnbk80dddEgF6LEUhE4eMCblA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=W5XbiWtuhMenbbX2eUsoinsN+8nRR/kk7KRzLM8u5n0ct6UJ6TQgEMjP7g7qlnGGs 2OVjjAHxKwg5pjH9dqMzfV222zpLYZ/4BpTR7v7ZCSUSb9jtV8BcjfGrC0a/Y7Nhe8 72PtsNoXrMmSGA5Rtsqncf24gdJ8qlDxXHN3WtRUJKeMt7zKVZkNWBC+ElyUbnBE3r 9+8EDRyGXj7XaXJTyEfdXze96jJhrwyIlAESgXyTKCXz+LfKhh7NDX+ciCPw2ypc2E usyZxZNSzHp7HWwnbbdBDf9vxIu5tWnhCC7dSJYUjPRNH7Uy7lq+/9b+s74HUGmrBx KVs56ZQh4lioA== From: Jiri Olsa To: stable@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , "H. Peter Anvin" , Ingo Molnar , Masami Hiramatsu , Thomas Gleixner , linux-mm@kvack.org, bpf@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, Tsahee Zidenberg , Andrii Nakryiko , Christoph Hellwig , =?UTF-8?q?Mah=C3=A9=20Tardy?= , linux-arm-kernel@lists.infradead.org Subject: [RFC PATCH stable 5.4 7/8] bpf: rework the compat kernel probe handling Date: Mon, 22 May 2023 22:33:51 +0200 Message-Id: <20230522203352.738576-8-jolsa@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230522203352.738576-1-jolsa@kernel.org> References: <20230522203352.738576-1-jolsa@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230522_133541_319134_BA715B56 X-CRM114-Status: GOOD ( 21.89 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Christoph Hellwig commit 8d92db5c04d10381f4db70ed99b1b576f5db18a7 upstream. [Conflicts due to applying hunks only to the functions that were taken in 6ae08ae3dea2 upstream commit backport earlier] Instead of using the dangerous probe_kernel_read and strncpy_from_unsafe helpers, rework the compat probes to check if an address is a kernel or userspace one, and then use the low-level kernel or user probe helper shared by the proper kernel and user probe helpers. This slightly changes behavior as the compat probe on a user address doesn't check the lockdown flags, just as the pure user probes do. Signed-off-by: Christoph Hellwig Signed-off-by: Andrew Morton Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Masami Hiramatsu Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20200521152301.2587579-14-hch@lst.de Signed-off-by: Linus Torvalds --- kernel/trace/bpf_trace.c | 93 +++++++++++++++++++++++++++------------- 1 file changed, 64 insertions(+), 29 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index d1fd13a47bdf..a46256f99229 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -139,65 +139,99 @@ static const struct bpf_func_proto bpf_override_return_proto = { #endif static __always_inline int -bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr, - const bool compat) +bpf_probe_read_user_common(void *dst, u32 size, const void __user *unsafe_ptr) { - int ret = security_locked_down(LOCKDOWN_BPF_READ); + int ret; + ret = probe_user_read(dst, unsafe_ptr, size); if (unlikely(ret < 0)) - goto out; - ret = compat ? probe_kernel_read(dst, unsafe_ptr, size) : - probe_kernel_read_strict(dst, unsafe_ptr, size); - if (unlikely(ret < 0)) -out: memset(dst, 0, size); return ret; } -BPF_CALL_3(bpf_probe_read_compat, void *, dst, u32, size, - const void *, unsafe_ptr) +static __always_inline int +bpf_probe_read_user_str_common(void *dst, u32 size, + const void __user *unsafe_ptr) { - return bpf_probe_read_kernel_common(dst, size, unsafe_ptr, true); + int ret; + + ret = strncpy_from_user_nofault(dst, unsafe_ptr, size); + if (unlikely(ret < 0)) + memset(dst, 0, size); + return ret; } -static const struct bpf_func_proto bpf_probe_read_compat_proto = { - .func = bpf_probe_read_compat, - .gpl_only = true, - .ret_type = RET_INTEGER, - .arg1_type = ARG_PTR_TO_UNINIT_MEM, - .arg2_type = ARG_CONST_SIZE_OR_ZERO, - .arg3_type = ARG_ANYTHING, -}; +static __always_inline int +bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr) +{ + int ret = security_locked_down(LOCKDOWN_BPF_READ); + + if (unlikely(ret < 0)) + goto fail; + ret = probe_kernel_read_strict(dst, unsafe_ptr, size); + if (unlikely(ret < 0)) + goto fail; + return ret; +fail: + memset(dst, 0, size); + return ret; +} static __always_inline int -bpf_probe_read_kernel_str_common(void *dst, u32 size, const void *unsafe_ptr, - const bool compat) +bpf_probe_read_kernel_str_common(void *dst, u32 size, const void *unsafe_ptr) { int ret = security_locked_down(LOCKDOWN_BPF_READ); if (unlikely(ret < 0)) - goto out; + goto fail; + /* - * The strncpy_from_unsafe_*() call will likely not fill the entire - * buffer, but that's okay in this circumstance as we're probing + * The strncpy_from_kernel_nofault() call will likely not fill the + * entire buffer, but that's okay in this circumstance as we're probing * arbitrary memory anyway similar to bpf_probe_read_*() and might * as well probe the stack. Thus, memory is explicitly cleared * only in error case, so that improper users ignoring return * code altogether don't copy garbage; otherwise length of string * is returned that can be used for bpf_perf_event_output() et al. */ - ret = compat ? strncpy_from_unsafe(dst, unsafe_ptr, size) : - strncpy_from_kernel_nofault(dst, unsafe_ptr, size); + ret = strncpy_from_kernel_nofault(dst, unsafe_ptr, size); if (unlikely(ret < 0)) -out: - memset(dst, 0, size); + goto fail; + + return 0; +fail: + memset(dst, 0, size); return ret; } +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE +BPF_CALL_3(bpf_probe_read_compat, void *, dst, u32, size, + const void *, unsafe_ptr) +{ + if ((unsigned long)unsafe_ptr < TASK_SIZE) { + return bpf_probe_read_user_common(dst, size, + (__force void __user *)unsafe_ptr); + } + return bpf_probe_read_kernel_common(dst, size, unsafe_ptr); +} + +static const struct bpf_func_proto bpf_probe_read_compat_proto = { + .func = bpf_probe_read_compat, + .gpl_only = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_UNINIT_MEM, + .arg2_type = ARG_CONST_SIZE_OR_ZERO, + .arg3_type = ARG_ANYTHING, +}; + BPF_CALL_3(bpf_probe_read_compat_str, void *, dst, u32, size, const void *, unsafe_ptr) { - return bpf_probe_read_kernel_str_common(dst, size, unsafe_ptr, true); + if ((unsigned long)unsafe_ptr < TASK_SIZE) { + return bpf_probe_read_user_str_common(dst, size, + (__force void __user *)unsafe_ptr); + } + return bpf_probe_read_kernel_str_common(dst, size, unsafe_ptr); } static const struct bpf_func_proto bpf_probe_read_compat_str_proto = { @@ -208,6 +242,7 @@ static const struct bpf_func_proto bpf_probe_read_compat_str_proto = { .arg2_type = ARG_CONST_SIZE_OR_ZERO, .arg3_type = ARG_ANYTHING, }; +#endif /* CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE */ BPF_CALL_3(bpf_probe_write_user, void __user *, unsafe_ptr, const void *, src, u32, size) -- 2.40.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel