From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: passt.top; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: passt.top; dkim=pass (2048-bit key; secure) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.a=rsa-sha256 header.s=202512 header.b=uydyGn0G; dkim-atps=neutral Received: from mail.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) by passt.top (Postfix) with ESMTPS id 41DF85A0271 for ; Fri, 12 Dec 2025 08:10:43 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202512; t=1765523440; bh=q1j7/rg3+UJNk5YwlRitsD8rf4o77gMFt9wKx7HZFA4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uydyGn0GhBMsHC1np+n7q+Nc+XxdMiEgUaYsQ8XbKS+4u7U2ONXvPitvH5YHVYnXj tHgGAgdmvIoUzIvJVkNJUN2SyG6tZwxZ1uC+SNrFY25axaJbL8Y/O9i0XEtGGMa5ET 1sMU96TF3XyIo6sUzi97ho2BbE3mBJMcRziLWyTPVqgOvLEC4Qw/OTE92/lNvP7Eth 5GY9I2VMxXKh+O3qUsadkyfalfRo2RgOw0AdDZqLlnXLwqYB/ug0NgQ6jLH3TedwcB ESSvc/EdCF/XiwRAmucJzxrGtJhQ5fixUkabV2xU580ijVHjCaHyPdTylXReHoX/cY gYiS0T36fGBRg== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4dSLFr2073z4wMS; Fri, 12 Dec 2025 18:10:40 +1100 (AEDT) From: David Gibson To: passt-dev@passt.top, Stefano Brivio Subject: [PATCH 4/5] conf: Accurately record ifname and address for outbound forwards Date: Fri, 12 Dec 2025 18:10:37 +1100 Message-ID: <20251212071038.3943933-5-david@gibson.dropbear.id.au> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251212071038.3943933-1-david@gibson.dropbear.id.au> References: <20251212071038.3943933-1-david@gibson.dropbear.id.au> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-ID-Hash: TCISNDQO6BNIQJ23NJZCHGMFJRZN2XHL X-Message-ID-Hash: TCISNDQO6BNIQJ23NJZCHGMFJRZN2XHL X-MailFrom: dgibson@gandalf.ozlabs.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: David Gibson X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: -T and -U options don't allow specifying a listening address. Usually this will listen on *%lo in the guest. However on kernels without unprivileged SO_BINDTODEVICE that's not possible so we instead listen separately on 127.0.0.1 and ::1. Currently that's handled at the point we actually set up the listens, we record both address and ifname as NULL in the forwarding table entry. That will cause trouble for future extensions we want, so update this to accurately create the forwarding table: either a single entry with ifname == "lo" or two entries with address of 127.0.0.1 and ::1. As a bonus, this gives the user a warning if they specify an explicit outbound forwarding on a kernel without SO_BINDTODEVICE. The existing warning for missing SO_BINDTODEVICE (incorrectly) only covers the case of -T auto or -U auto. Signed-off-by: David Gibson --- conf.c | 38 ++++++++++++++++++++++++++++++-------- 1 file changed, 30 insertions(+), 8 deletions(-) diff --git a/conf.c b/conf.c index 88971d04..b24ab407 100644 --- a/conf.c +++ b/conf.c @@ -157,12 +157,6 @@ static void conf_ports_range_except(const struct ctx *c, char optname, optname, optarg); } - if (ifname && c->no_bindtodevice) { - die( -"Device binding for '-%c %s' unsupported (requires kernel 5.7+)", - optname, optarg); - } - for (base = first; base <= last; base++) { if (bitmap_isset(exclude, base)) continue; @@ -204,8 +198,27 @@ static void conf_ports_range_except(const struct ctx *c, char optname, } } - fwd_table_add(fwd, flags, addr, ifname, - base, i - 1, base + delta); + if ((optname == 'T' || optname == 'U') && c->no_bindtodevice) { + /* FIXME: Once the fwd bitmaps are removed, move this + * workaround to the caller + */ + ASSERT(!addr && ifname && !strcmp(ifname, "lo")); + warn( +"SO_BINDTODEVICE unavailable, forwarding only 127.0.0.1 and ::1 for '-%c %s'", + optname, optarg); + + if (c->ifi4) { + fwd_table_add(fwd, flags, &inany_loopback4, NULL, + base, i - 1, base + delta); + } + if (c->ifi6) { + fwd_table_add(fwd, flags, &inany_loopback6, NULL, + base, i - 1, base + delta); + } + } else { + fwd_table_add(fwd, flags, addr, ifname, + base, i - 1, base + delta); + } base = i - 1; } @@ -352,6 +365,15 @@ static void conf_ports(const struct ctx *c, char optname, const char *optarg, } } while ((p = next_chunk(p, ','))); + if (ifname && c->no_bindtodevice) { + die( +"Device binding for '-%c %s' unsupported (requires kernel 5.7+)", + optname, optarg); + } + /* Outbound forwards come from guest loopback */ + if ((optname == 'T' || optname == 'U') && !ifname) + ifname = "lo"; + if (exclude_only) { /* Exclude ephemeral ports */ for (i = 0; i < NUM_PORTS; i++) -- 2.52.0