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@@ -47,11 +47,29 @@
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*
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* The hardware you're dealing with doesn't calculate the full checksum
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* (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums
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- * for specific protocols e.g. TCP/UDP/SCTP, then, for such packets it will
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- * set CHECKSUM_UNNECESSARY if their checksums are okay. skb->csum is still
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- * undefined in this case though. It is a bad option, but, unfortunately,
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- * nowadays most vendors do this. Apparently with the secret goal to sell
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- * you new devices, when you will add new protocol to your host, f.e. IPv6 8)
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+ * for specific protocols. For such packets it will set CHECKSUM_UNNECESSARY
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+ * if their checksums are okay. skb->csum is still undefined in this case
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+ * though. It is a bad option, but, unfortunately, nowadays most vendors do
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+ * this. Apparently with the secret goal to sell you new devices, when you
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+ * will add new protocol to your host, f.e. IPv6 8)
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+ *
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+ * CHECKSUM_UNNECESSARY is applicable to following protocols:
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+ * TCP: IPv6 and IPv4.
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+ * UDP: IPv4 and IPv6. A device may apply CHECKSUM_UNNECESSARY to a
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+ * zero UDP checksum for either IPv4 or IPv6, the networking stack
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+ * may perform further validation in this case.
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+ * GRE: only if the checksum is present in the header.
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+ * SCTP: indicates the CRC in SCTP header has been validated.
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+ *
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+ * skb->csum_level indicates the number of consecutive checksums found in
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+ * the packet minus one that have been verified as CHECKSUM_UNNECESSARY.
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+ * For instance if a device receives an IPv6->UDP->GRE->IPv4->TCP packet
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+ * and a device is able to verify the checksums for UDP (possibly zero),
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+ * GRE (checksum flag is set), and TCP-- skb->csum_level would be set to
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+ * two. If the device were only able to verify the UDP checksum and not
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+ * GRE, either because it doesn't support GRE checksum of because GRE
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+ * checksum is bad, skb->csum_level would be set to zero (TCP checksum is
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+ * not considered in this case).
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*
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* CHECKSUM_COMPLETE:
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*
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@@ -112,6 +130,9 @@
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#define CHECKSUM_COMPLETE 2
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#define CHECKSUM_PARTIAL 3
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+/* Maximum value in skb->csum_level */
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+#define SKB_MAX_CSUM_LEVEL 3
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+
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#define SKB_DATA_ALIGN(X) ALIGN(X, SMP_CACHE_BYTES)
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#define SKB_WITH_OVERHEAD(X) \
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((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
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@@ -571,11 +592,7 @@ struct sk_buff {
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__u8 wifi_acked:1;
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__u8 no_fcs:1;
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__u8 head_frag:1;
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- /* Encapsulation protocol and NIC drivers should use
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- * this flag to indicate to each other if the skb contains
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- * encapsulated packet or not and maybe use the inner packet
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- * headers if needed
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- */
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+ /* Indicates the inner headers are valid in the skbuff. */
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__u8 encapsulation:1;
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__u8 encap_hdr_csum:1;
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__u8 csum_valid:1;
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@@ -598,6 +615,11 @@ struct sk_buff {
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__u32 reserved_tailroom;
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};
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+ kmemcheck_bitfield_begin(flags3);
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+ __u8 csum_level:2;
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+ /* 14 bit hole */
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+ kmemcheck_bitfield_end(flags3);
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+
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__be16 inner_protocol;
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__u16 inner_transport_header;
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__u16 inner_network_header;
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@@ -1862,18 +1884,6 @@ static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
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return pskb_may_pull(skb, skb_network_offset(skb) + len);
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}
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-static inline void skb_pop_rcv_encapsulation(struct sk_buff *skb)
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-{
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- /* Only continue with checksum unnecessary if device indicated
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- * it is valid across encapsulation (skb->encapsulation was set).
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- */
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- if (skb->ip_summed == CHECKSUM_UNNECESSARY && !skb->encapsulation)
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- skb->ip_summed = CHECKSUM_NONE;
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-
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- skb->encapsulation = 0;
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- skb->csum_valid = 0;
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-}
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-
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/*
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* CPUs often take a performance hit when accessing unaligned memory
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* locations. The actual performance hit varies, it can be small if the
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@@ -2794,6 +2804,27 @@ static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
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0 : __skb_checksum_complete(skb);
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}
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+static inline void __skb_decr_checksum_unnecessary(struct sk_buff *skb)
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+{
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+ if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
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+ if (skb->csum_level == 0)
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+ skb->ip_summed = CHECKSUM_NONE;
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+ else
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+ skb->csum_level--;
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+ }
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+}
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+
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+static inline void __skb_incr_checksum_unnecessary(struct sk_buff *skb)
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+{
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+ if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
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+ if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
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+ skb->csum_level++;
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+ } else if (skb->ip_summed == CHECKSUM_NONE) {
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+ skb->ip_summed = CHECKSUM_UNNECESSARY;
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+ skb->csum_level = 0;
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+ }
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+}
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+
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/* Check if we need to perform checksum complete validation.
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*
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* Returns true if checksum complete is needed, false otherwise
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@@ -2805,6 +2836,7 @@ static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
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{
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if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {
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skb->csum_valid = 1;
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+ __skb_decr_checksum_unnecessary(skb);
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return false;
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}
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David S. Miller