From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-2848808-1517590783-2-3607205088622521692 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1517590783; b=PXPUzUPndSoh0bQHJgbXLS/XPol5fDjt49cYopi4FfCeu+4 2zlYa4+liX6Tl7wOBEyw+riHCGGKBbHO+RJeNxwmdzwQQjBW4XLKZ6CzML6tKWyU odCuEbcCxOPvWBwgNQ1VzHE3Vttn77i3WjZfReS7VQflCnG0nMPFuuAyEgUCTP8g VvXq3yNy5cJtGqCRL1fYn1HnK4467T4uVsfq1qDi0rkmLIOYGRhn/FIPbMLs1e3H Qr77M08cWIFIZn2HcYl/fattxIzEtGWfxvcceMI1yYtK+LmkPHFi6gQPFxsTPT66 FuF1hXliC4a9fNOvG/lBJtoZZEC55eedCZTZ4UA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-type:sender :list-id; s=arctest; t=1517590783; bh=75MuXyPI9RyJBIpm0lFf5ttmP4 F5QyoszXSZVDYW2cg=; b=rXU+h27dcBUSBW4HI2XlxSt+yLpCOoivj8QoS4aJsb C7OlI+gViJV0texClIbn2fg+1xDittRQOMadv2NL8d81eMfzMJ1ry2fevQOfik4a VR4tEhwsKDhIvXBqDIOEMvkoWuyd+QU95V0Kj++fcbFvuCgKM8L0abXMwW3dLiL9 Uq6tUCB+S80wfXuJAExQ86e4p+y9PYlVlHC/+jjohfHoKSIbP1BMaLTTKbgT8Sjg od38///sGOZ8cWEjw165GB2h6wxCx4luiE/DQ7fuO7fi8/g2icrSxMYaNGYDCeC8 9qBtbI/7rM9F62B5m9UXIKCjrn3uJN6+xvoVILgLbkeg== ARC-Authentication-Results: i=1; mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Authentication-Results: mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752497AbeBBQ7k (ORCPT ); Fri, 2 Feb 2018 11:59:40 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:34436 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752050AbeBBQ7g (ORCPT ); Fri, 2 Feb 2018 11:59:36 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann Subject: [PATCH 4.4 10/67] bpf: reject stores into ctx via st and xadd Date: Fri, 2 Feb 2018 17:57:39 +0100 Message-Id: <20180202140816.368433911@linuxfoundation.org> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180202140815.091718203@linuxfoundation.org> References: <20180202140815.091718203@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann [ upstream commit f37a8cb84cce18762e8f86a70bd6a49a66ab964c ] Alexei found that verifier does not reject stores into context via BPF_ST instead of BPF_STX. And while looking at it, we also should not allow XADD variant of BPF_STX. The context rewriter is only assuming either BPF_LDX_MEM- or BPF_STX_MEM-type operations, thus reject anything other than that so that assumptions in the rewriter properly hold. Add test cases as well for BPF selftests. Fixes: d691f9e8d440 ("bpf: allow programs to write to certain skb fields") Reported-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/verifier.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -683,6 +683,13 @@ static bool is_pointer_value(struct veri } } +static bool is_ctx_reg(struct verifier_env *env, int regno) +{ + const struct reg_state *reg = &env->cur_state.regs[regno]; + + return reg->type == PTR_TO_CTX; +} + /* check whether memory at (regno + off) is accessible for t = (read | write) * if t==write, value_regno is a register which value is stored into memory * if t==read, value_regno is a register which will receive the value from memory @@ -779,6 +786,12 @@ static int check_xadd(struct verifier_en return -EACCES; } + if (is_ctx_reg(env, insn->dst_reg)) { + verbose("BPF_XADD stores into R%d context is not allowed\n", + insn->dst_reg); + return -EACCES; + } + /* check whether atomic_add can read the memory */ err = check_mem_access(env, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_READ, -1); @@ -1909,6 +1922,12 @@ static int do_check(struct verifier_env if (err) return err; + if (is_ctx_reg(env, insn->dst_reg)) { + verbose("BPF_ST stores into R%d context is not allowed\n", + insn->dst_reg); + return -EACCES; + } + /* check that memory (dst_reg + off) is writeable */ err = check_mem_access(env, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_WRITE,