From owner-svn-src-stable-11@freebsd.org Mon Dec 23 10:06:33 2019 Return-Path: Delivered-To: svn-src-stable-11@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 668D51EB93D; Mon, 23 Dec 2019 10:06:33 +0000 (UTC) (envelope-from ae@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 47hFPP28gsz4Ssm; Mon, 23 Dec 2019 10:06:33 +0000 (UTC) (envelope-from ae@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 4532EE37A; Mon, 23 Dec 2019 10:06:33 +0000 (UTC) (envelope-from ae@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id xBNA6X35057402; Mon, 23 Dec 2019 10:06:33 GMT (envelope-from ae@FreeBSD.org) Received: (from ae@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id xBNA6XJd057401; Mon, 23 Dec 2019 10:06:33 GMT (envelope-from ae@FreeBSD.org) Message-Id: <201912231006.xBNA6XJd057401@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: ae set sender to ae@FreeBSD.org using -f From: "Andrey V. Elsukov" Date: Mon, 23 Dec 2019 10:06:33 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r356036 - stable/11/sys/netpfil/ipfw X-SVN-Group: stable-11 X-SVN-Commit-Author: ae X-SVN-Commit-Paths: stable/11/sys/netpfil/ipfw X-SVN-Commit-Revision: 356036 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-stable-11@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: SVN commit messages for only the 11-stable src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 23 Dec 2019 10:06:33 -0000 Author: ae Date: Mon Dec 23 10:06:32 2019 New Revision: 356036 URL: https://svnweb.freebsd.org/changeset/base/356036 Log: MFC r355712: Make TCP options parsing stricter. Rework tcpopts_parse() to be more strict. Use const pointer. Add length checks for specific TCP options. The main purpose of the change is avoiding of possible out of mbuf's data access. Reported by: Maxime Villard Modified: stable/11/sys/netpfil/ipfw/ip_fw2.c Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/netpfil/ipfw/ip_fw2.c ============================================================================== --- stable/11/sys/netpfil/ipfw/ip_fw2.c Mon Dec 23 10:02:55 2019 (r356035) +++ stable/11/sys/netpfil/ipfw/ip_fw2.c Mon Dec 23 10:06:32 2019 (r356036) @@ -328,22 +328,27 @@ ipopts_match(struct ip *ip, ipfw_insn *cmd) return (flags_match(cmd, bits)); } +/* + * Parse TCP options. The logic copied from tcp_dooptions(). + */ static int -tcpopts_parse(struct tcphdr *tcp, uint16_t *mss) +tcpopts_parse(const struct tcphdr *tcp, uint16_t *mss) { - u_char *cp = (u_char *)(tcp + 1); + const u_char *cp = (const u_char *)(tcp + 1); int optlen, bits = 0; - int x = (tcp->th_off << 2) - sizeof(struct tcphdr); + int cnt = (tcp->th_off << 2) - sizeof(struct tcphdr); - for (; x > 0; x -= optlen, cp += optlen) { + for (; cnt > 0; cnt -= optlen, cp += optlen) { int opt = cp[0]; if (opt == TCPOPT_EOL) break; if (opt == TCPOPT_NOP) optlen = 1; else { + if (cnt < 2) + break; optlen = cp[1]; - if (optlen <= 0) + if (optlen < 2 || optlen > cnt) break; } @@ -352,22 +357,31 @@ tcpopts_parse(struct tcphdr *tcp, uint16_t *mss) break; case TCPOPT_MAXSEG: + if (optlen != TCPOLEN_MAXSEG) + break; bits |= IP_FW_TCPOPT_MSS; if (mss != NULL) *mss = be16dec(cp + 2); break; case TCPOPT_WINDOW: - bits |= IP_FW_TCPOPT_WINDOW; + if (optlen == TCPOLEN_WINDOW) + bits |= IP_FW_TCPOPT_WINDOW; break; case TCPOPT_SACK_PERMITTED: + if (optlen == TCPOLEN_SACK_PERMITTED) + bits |= IP_FW_TCPOPT_SACK; + break; + case TCPOPT_SACK: - bits |= IP_FW_TCPOPT_SACK; + if (optlen > 2 && (optlen - 2) % TCPOLEN_SACK == 0) + bits |= IP_FW_TCPOPT_SACK; break; case TCPOPT_TIMESTAMP: - bits |= IP_FW_TCPOPT_TS; + if (optlen == TCPOLEN_TIMESTAMP) + bits |= IP_FW_TCPOPT_TS; break; } }