From 698aa6c46bf09070310cd2c8893ea2de5a796644 Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Sat, 12 Jun 2021 09:37:33 -0500 Subject: [PATCH] net: qualcomm: rmnet: remove unneeded code The previous patch makes rmnet_map_ipv4_dl_csum_trailer() return early with an error if it is determined that the computed checksum for the IP payload does not match what was expected. If the computed checksum *does* match the expected value, the IP payload (i.e., the transport message), can be considered good. There is no need to do any further processing of the message. This means a big block of code is unnecessary for validating the transport checksum value, and can be removed. Make comparable changes in rmnet_map_ipv6_dl_csum_trailer(). Signed-off-by: Alex Elder Signed-off-by: David S. Miller --- .../net/ethernet/qualcomm/rmnet/rmnet_map_data.c | 75 ++++------------------ 1 file changed, 14 insertions(+), 61 deletions(-) diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c index a05124eb8602..033b8ad3d735 100644 --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c @@ -37,7 +37,6 @@ rmnet_map_ipv4_dl_csum_trailer(struct sk_buff *skb, void *txporthdr = skb->data + ip4h->ihl * 4; __sum16 *csum_field, pseudo_csum; __sum16 ip_payload_csum; - __sum16 csum_value_final; /* Computing the checksum over just the IPv4 header--including its * checksum field--should yield 0. If it doesn't, the IP header @@ -93,37 +92,15 @@ rmnet_map_ipv4_dl_csum_trailer(struct sk_buff *skb, pseudo_csum = ~csum_tcpudp_magic(ip4h->saddr, ip4h->daddr, ntohs(ip4h->tot_len) - ip4h->ihl * 4, ip4h->protocol, 0); - pseudo_csum = csum16_add(ip_payload_csum, (__force __be16)pseudo_csum); /* The cast is required to ensure only the low 16 bits are examined */ - if ((__sum16)~pseudo_csum) { + if (ip_payload_csum != (__sum16)~pseudo_csum) { priv->stats.csum_validation_failed++; return -EINVAL; } - csum_value_final = ~csum16_sub(pseudo_csum, (__force __be16)*csum_field); - - if (unlikely(!csum_value_final)) { - switch (ip4h->protocol) { - case IPPROTO_UDP: - /* RFC 768 - DL4 1's complement rule for UDP csum 0 */ - csum_value_final = ~csum_value_final; - break; - - case IPPROTO_TCP: - /* DL4 Non-RFC compliant TCP checksum found */ - if (*csum_field == (__force __sum16)0xFFFF) - csum_value_final = ~csum_value_final; - break; - } - } - if (csum_value_final == *csum_field) { - priv->stats.csum_ok++; - return 0; - } else { - priv->stats.csum_validation_failed++; - return -EINVAL; - } + priv->stats.csum_ok++; + return 0; } #if IS_ENABLED(CONFIG_IPV6) @@ -137,7 +114,6 @@ rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb, __sum16 *csum_field, pseudo_csum; __sum16 ip6_payload_csum; __be16 ip_header_csum; - __sum16 csum_value_final; u32 length; /* Checksum offload is only supported for UDP and TCP protocols; @@ -154,11 +130,6 @@ rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb, * transport checksum from this, we first subract the contribution * of the IP header from the trailer checksum. We then add the * checksum computed over the pseudo header. - * - * It's sufficient to compare the IP payload checksum with the - * negated pseudo checksum to determine whether the packet - * checksum was good. (See further explanation in comments - * in rmnet_map_ipv4_dl_csum_trailer()). */ ip_header_csum = (__force __be16)ip_fast_csum(ip6h, sizeof(*ip6h) / 4); ip6_payload_csum = ~csum16_sub((__force __sum16)csum_trailer->csum_value, @@ -169,40 +140,22 @@ rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb, ntohs(ip6h->payload_len); pseudo_csum = ~csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, length, ip6h->nexthdr, 0); - pseudo_csum = csum16_add(ip6_payload_csum, (__force __be16)pseudo_csum); - /* The cast is required to ensure only the low 16 bits are examined */ - if ((__sum16)~pseudo_csum) { + /* It's sufficient to compare the IP payload checksum with the + * negated pseudo checksum to determine whether the packet + * checksum was good. (See further explanation in comments + * in rmnet_map_ipv4_dl_csum_trailer()). + * + * The cast is required to ensure only the low 16 bits are + * examined. + */ + if (ip6_payload_csum != (__sum16)~pseudo_csum) { priv->stats.csum_validation_failed++; return -EINVAL; } - csum_value_final = ~csum16_sub(pseudo_csum, (__force __be16)*csum_field); - - if (unlikely(csum_value_final == 0)) { - switch (ip6h->nexthdr) { - case IPPROTO_UDP: - /* RFC 2460 section 8.1 - * DL6 One's complement rule for UDP checksum 0 - */ - csum_value_final = ~csum_value_final; - break; - - case IPPROTO_TCP: - /* DL6 Non-RFC compliant TCP checksum found */ - if (*csum_field == (__force __sum16)0xFFFF) - csum_value_final = ~csum_value_final; - break; - } - } - - if (csum_value_final == *csum_field) { - priv->stats.csum_ok++; - return 0; - } else { - priv->stats.csum_validation_failed++; - return -EINVAL; - } + priv->stats.csum_ok++; + return 0; } #endif -- 2.11.0