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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F26CAC47404 for ; Sat, 5 Oct 2019 05:03:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C9442222C0 for ; Sat, 5 Oct 2019 05:03:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570251823; bh=BO+/jrpc2aaV0Us1ScAFzXHFCzNEr+gX1cE+sRcUzpA=; h=From:To:CC:Subject:Date:In-Reply-To:References:List-ID:From; b=en26Wr7MXYCiQ6VfpKVDN/tiNogJ8z8Bufn5F7PGty2qadiEDpQ0CVuT1cWF/8jO3 RaY4iFRyqu1KSTF3iKZBnXyU1CTMteYa0EjBeIjNPokCis0j7jqjcP1HG7K9L+DrAv wY1BAPhf6xOnNEWmseQ7bqd5mEaz8Uu7OVx2KEds= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727118AbfJEFDn convert rfc822-to-8bit (ORCPT ); Sat, 5 Oct 2019 01:03:43 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:64978 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727059AbfJEFDm (ORCPT ); Sat, 5 Oct 2019 01:03:42 -0400 Received: from pps.filterd (m0109334.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id x9553ZAQ012985 for ; Fri, 4 Oct 2019 22:03:41 -0700 Received: from mail.thefacebook.com (mailout.thefacebook.com [199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2ve8593eng-9 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT) for ; Fri, 04 Oct 2019 22:03:41 -0700 Received: from 2401:db00:30:600c:face:0:1f:0 (2620:10d:c081:10::13) by mail.thefacebook.com (2620:10d:c081:35::130) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA) id 15.1.1713.5; Fri, 4 Oct 2019 22:03:27 -0700 Received: by devbig007.ftw2.facebook.com (Postfix, from userid 572438) id 281E776091D; Fri, 4 Oct 2019 22:03:27 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Alexei Starovoitov Smtp-Origin-Hostname: devbig007.ftw2.facebook.com To: CC: , , , , Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH bpf-next 06/10] bpf: add support for BTF pointers to interpreter Date: Fri, 4 Oct 2019 22:03:10 -0700 Message-ID: <20191005050314.1114330-7-ast@kernel.org> X-Mailer: git-send-email 2.20.0 In-Reply-To: <20191005050314.1114330-1-ast@kernel.org> References: <20191005050314.1114330-1-ast@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,1.0.8 definitions=2019-10-05_02:2019-10-03,2019-10-05 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 adultscore=0 malwarescore=0 clxscore=1034 bulkscore=0 phishscore=0 lowpriorityscore=0 mlxlogscore=794 impostorscore=0 mlxscore=0 priorityscore=1501 suspectscore=1 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1908290000 definitions=main-1910050045 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Pointer to BTF object is a pointer to kernel object or NULL. The memory access in the interpreter has to be done via probe_kernel_read to avoid page faults. Signed-off-by: Alexei Starovoitov --- include/linux/filter.h | 3 +++ kernel/bpf/core.c | 19 +++++++++++++++++++ kernel/bpf/verifier.c | 8 ++++++++ 3 files changed, 30 insertions(+) diff --git a/include/linux/filter.h b/include/linux/filter.h index d3d51d7aff2c..22ebea2e64ea 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -65,6 +65,9 @@ struct ctl_table_header; /* unused opcode to mark special call to bpf_tail_call() helper */ #define BPF_TAIL_CALL 0xf0 +/* unused opcode to mark special load instruction. Same as BPF_ABS */ +#define BPF_PROBE_MEM 0x20 + /* unused opcode to mark call to interpreter with arguments */ #define BPF_CALL_ARGS 0xe0 diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 66088a9e9b9e..8a765bbd33f0 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1291,6 +1291,11 @@ bool bpf_opcode_in_insntable(u8 code) } #ifndef CONFIG_BPF_JIT_ALWAYS_ON +u64 __weak bpf_probe_read(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 @@ -1310,6 +1315,10 @@ static u64 __no_fgcse ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u6 /* Non-UAPI available opcodes. */ [BPF_JMP | BPF_CALL_ARGS] = &&JMP_CALL_ARGS, [BPF_JMP | BPF_TAIL_CALL] = &&JMP_TAIL_CALL, + [BPF_LDX | BPF_PROBE_MEM | BPF_B] = &&LDX_PROBE_MEM_B, + [BPF_LDX | BPF_PROBE_MEM | BPF_H] = &&LDX_PROBE_MEM_H, + [BPF_LDX | BPF_PROBE_MEM | BPF_W] = &&LDX_PROBE_MEM_W, + [BPF_LDX | BPF_PROBE_MEM | BPF_DW] = &&LDX_PROBE_MEM_DW, }; #undef BPF_INSN_3_LBL #undef BPF_INSN_2_LBL @@ -1542,6 +1551,16 @@ static u64 __no_fgcse ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u6 LDST(W, u32) LDST(DW, u64) #undef LDST +#define LDX_PROBE(SIZEOP, SIZE) \ + LDX_PROBE_MEM_##SIZEOP: \ + bpf_probe_read(&DST, SIZE, (const void *)(long) SRC); \ + CONT; + LDX_PROBE(B, 1) + LDX_PROBE(H, 2) + LDX_PROBE(W, 4) + LDX_PROBE(DW, 8) +#undef LDX_PROBE + STX_XADD_W: /* lock xadd *(u32 *)(dst_reg + off16) += src_reg */ atomic_add((u32) SRC, (atomic_t *)(unsigned long) (DST + insn->off)); diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 3c155873ffea..b81f46371bb9 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7509,6 +7509,7 @@ static bool reg_type_mismatch_ok(enum bpf_reg_type type) case PTR_TO_TCP_SOCK: case PTR_TO_TCP_SOCK_OR_NULL: case PTR_TO_XDP_SOCK: + case PTR_TO_BTF_ID: return false; default: return true; @@ -8650,6 +8651,13 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) case PTR_TO_XDP_SOCK: convert_ctx_access = bpf_xdp_sock_convert_ctx_access; break; + case PTR_TO_BTF_ID: + if (type == BPF_WRITE) { + verbose(env, "Writes through BTF pointers are not allowed\n"); + return -EINVAL; + } + insn->code = BPF_LDX | BPF_PROBE_MEM | BPF_SIZE((insn)->code); + continue; default: continue; } -- 2.20.0