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[67.207.112.138]) by smtp.gmail.com with ESMTPSA id s3sm4082810pfk.7.2017.11.16.06.06.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 16 Nov 2017 06:06:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=skyportsystems.com; s=google; h=from:to:cc:subject:date:message-id; bh=gG1ugFxYRRM+SegX7IWwXUE2cu2asw4+TG0GwlzLXQs=; b=mtnNgZrICty6GQa45cF+Xb7tIqG7wof2I+AsUz6zJb9+qI8u7+IjEhTUAA5qpsrDxg CDrW2bxGmVs5GiECRVjWn/vzTIDaeNA72rJk+VP9aGTRlLXNi7yehD1e9R4hLodE+q/q 6K2jPZzlh3wbQLeHiDqt5dquy5sWtyv8d3v8c= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=gG1ugFxYRRM+SegX7IWwXUE2cu2asw4+TG0GwlzLXQs=; b=dArR2umcXeuB89cj83SxsGH2qOv/g5lPRsclSOaBQvvFWmg5WMmGViWMOZ7f+vOidT ZW6lhN7GWz1bTWv+D+9I5J9JVOSdga/vpj66G2DxCH3nj9eOc9TGYbltEFQWR3R6HHSa H+uLGEDspoJuGomGlOCP+muA0UgAQ9TKroq5iJq1lztNsbvSIsFh0X8FCe7i2sxZx589 dGlYd6kzIpkpJNE8zqFo9ranSj6YAjqxr44AdZod2wch+3y4QOE9NGOYGrrdyZ/cEAOX 2tkEAjs2dFHeomamwiIXc2L+ofIE5Fti1Z59TPwxJc2qyfpoUiF4QVGtmUD6LwgNue4M wQqA== X-Gm-Message-State: AJaThX5nLpEK7Ur7lRtzExGCithvQzPy+om9FR57RBlPllff9BZs7N70 WTU+2Amhu9JJPEQkkNKZqWBX3w== X-Google-Smtp-Source: AGs4zMar505q5oFQZOgukpM/JtkNOCsZPMkHEndcl+1LHuGUIrsguAyRgeTNkeLcgc10K4s0zmgaaQ== X-Received: by 10.84.240.196 with SMTP id l4mr1809177plt.149.1510841197768; Thu, 16 Nov 2017 06:06:37 -0800 (PST) To: Jason Wang , "Daniel P . Berrange" , Stefan Hajnoczi , Dmitry Fleytman Date: Thu, 16 Nov 2017 06:06:06 -0800 Message-Id: <1510841166-40615-1-git-send-email-eswierk@skyportsystems.com> X-Mailer: git-send-email 1.9.1 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:400e:c05::243 Subject: [Qemu-devel] [PATCH v3 REPOST] net: Transmit zero UDP checksum as 0xFFFF X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Ed Swierk via Qemu-devel Reply-To: Ed Swierk Cc: Ed Swierk , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZohoMail: RDKM_2 RSF_6 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" The checksum algorithm used by IPv4, TCP and UDP allows a zero value to be represented by either 0x0000 and 0xFFFF. But per RFC 768, a zero UDP checksum must be transmitted as 0xFFFF because 0x0000 is a special value meaning no checksum. Substitute 0xFFFF whenever a checksum is computed as zero when modifying a UDP datagram header. Doing this on IPv4 and TCP checksums is unnecessary but legal. Add a wrapper for net_checksum_finish() that makes the substitution. (We can't just change net_checksum_finish(), as that function is also used by receivers to verify checksums, and in that case the expected value is always 0x0000.) Signed-off-by: Ed Swierk --- v3: (Reposted to fix patch format) Leave net_tx_pkt_update_ip_checksums() alone since it's only computing a partial sum of the IP pseudo-header. Rename wrapper to net_checksum_finish_nozero() for clarity. v2: Add a wrapper net_checksum_finish_hdr() rather than duplicating the logic at every caller. --- hw/net/e1000.c | 2 +- hw/net/net_rx_pkt.c | 2 +- hw/net/net_tx_pkt.c | 2 +- hw/net/vmxnet3.c | 3 ++- include/net/checksum.h | 6 ++++++ 5 files changed, 11 insertions(+), 4 deletions(-) diff --git a/hw/net/e1000.c b/hw/net/e1000.c index 72a92be..804ec08 100644 --- a/hw/net/e1000.c +++ b/hw/net/e1000.c @@ -506,7 +506,7 @@ putsum(uint8_t *data, uint32_t n, uint32_t sloc, uint32= _t css, uint32_t cse) n =3D cse + 1; if (sloc < n-1) { sum =3D net_checksum_add(n-css, data+css); - stw_be_p(data + sloc, net_checksum_finish(sum)); + stw_be_p(data + sloc, net_checksum_finish_nozero(sum)); } } =20 diff --git a/hw/net/net_rx_pkt.c b/hw/net/net_rx_pkt.c index cef1c2e..98a5030 100644 --- a/hw/net/net_rx_pkt.c +++ b/hw/net/net_rx_pkt.c @@ -518,7 +518,7 @@ _net_rx_pkt_calc_l4_csum(struct NetRxPkt *pkt) cntr +=3D net_checksum_add_iov(pkt->vec, pkt->vec_len, pkt->l4hdr_off, csl, cso); =20 - csum =3D net_checksum_finish(cntr); + csum =3D net_checksum_finish_nozero(cntr); =20 trace_net_rx_pkt_l4_csum_calc_csum(pkt->l4hdr_off, csl, cntr, csum); =20 diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c index 20b2549..e29c881 100644 --- a/hw/net/net_tx_pkt.c +++ b/hw/net/net_tx_pkt.c @@ -486,7 +486,7 @@ static void net_tx_pkt_do_sw_csum(struct NetTxPkt *pkt) net_checksum_add_iov(iov, iov_len, pkt->virt_hdr.csum_start, csl, = cso); =20 /* Put the checksum obtained into the packet */ - csum =3D cpu_to_be16(net_checksum_finish(csum_cntr)); + csum =3D cpu_to_be16(net_checksum_finish_nozero(csum_cntr)); iov_from_buf(iov, iov_len, csum_offset, &csum, sizeof csum); } =20 diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c index 8c4bae5..cdc307d 100644 --- a/hw/net/vmxnet3.c +++ b/hw/net/vmxnet3.c @@ -972,7 +972,8 @@ static void vmxnet3_rx_need_csum_calculate(struct NetRx= Pkt *pkt, data =3D (uint8_t *)pkt_data + vhdr->csum_start; len =3D pkt_len - vhdr->csum_start; /* Put the checksum obtained into the packet */ - stw_be_p(data + vhdr->csum_offset, net_raw_checksum(data, len)); + stw_be_p(data + vhdr->csum_offset, + net_checksum_finish_nozero(net_checksum_add(len, data))); =20 vhdr->flags &=3D ~VIRTIO_NET_HDR_F_NEEDS_CSUM; vhdr->flags |=3D VIRTIO_NET_HDR_F_DATA_VALID; diff --git a/include/net/checksum.h b/include/net/checksum.h index 7df472c..05a0d27 100644 --- a/include/net/checksum.h +++ b/include/net/checksum.h @@ -34,6 +34,12 @@ net_checksum_add(int len, uint8_t *buf) } =20 static inline uint16_t +net_checksum_finish_nozero(uint32_t sum) +{ + return net_checksum_finish(sum) ?: 0xFFFF; +} + +static inline uint16_t net_raw_checksum(uint8_t *data, int length) { return net_checksum_finish(net_checksum_add(length, data)); --=20 1.9.1