On Tue, Jan 31, 2023 at 09:12:51PM +0100, Christian Weisgerber wrote:
> Jan Klemkow:
> 
> >  - I turned the KASSERTS to returns.
> >  - Check if the mbuf is large enough for an ether header.
> >  - additionally #ifdef'd INET6 around the ip6_hdr in the new struct
> 
> For non-initial fragments of TCP/UDP packets, ether_extract_headers()
> will create ext.tcp/ext.udp pointers that do not point to a protocol
> header.  Should there be a check to exclude fragments?

yes.  bluhm also suggested this solution to me.

ok?

Thanks,
Jan

Index: dev/pci/if_ix.c
===================================================================
RCS file: /cvs/src/sys/dev/pci/if_ix.c,v
retrieving revision 1.191
diff -u -p -r1.191 if_ix.c
--- dev/pci/if_ix.c     26 Jan 2023 07:32:39 -0000      1.191
+++ dev/pci/if_ix.c     31 Jan 2023 21:05:40 -0000
@@ -2477,25 +2477,16 @@ static inline int
 ixgbe_csum_offload(struct mbuf *mp, uint32_t *vlan_macip_lens,
     uint32_t *type_tucmd_mlhl, uint32_t *olinfo_status)
 {
-       struct ether_header *eh = mtod(mp, struct ether_header *);
-       struct mbuf *m;
-       int hoff;
+       struct ether_extracted ext;
        int offload = 0;
        uint32_t iphlen;
-       uint8_t ipproto;
 
-       *vlan_macip_lens |= (sizeof(*eh) << IXGBE_ADVTXD_MACLEN_SHIFT);
+       ether_extract_headers(mp, &ext);
 
-       switch (ntohs(eh->ether_type)) {
-       case ETHERTYPE_IP: {
-               struct ip *ip;
+       *vlan_macip_lens |= (sizeof(*ext.eh) << IXGBE_ADVTXD_MACLEN_SHIFT);
 
-               m = m_getptr(mp, sizeof(*eh), &hoff);
-               KASSERT(m != NULL && m->m_len - hoff >= sizeof(*ip));
-               ip = (struct ip *)(mtod(m, caddr_t) + hoff);
-
-               iphlen = ip->ip_hl << 2;
-               ipproto = ip->ip_p;
+       if (ext.ip4) {
+               iphlen = ext.ip4->ip_hl << 2;
 
                if (ISSET(mp->m_pkthdr.csum_flags, M_IPV4_CSUM_OUT)) {
                        *olinfo_status |= IXGBE_TXD_POPTS_IXSM << 8;
@@ -2503,46 +2494,30 @@ ixgbe_csum_offload(struct mbuf *mp, uint
                }
 
                *type_tucmd_mlhl |= IXGBE_ADVTXD_TUCMD_IPV4;
-               break;
-       }
-
 #ifdef INET6
-       case ETHERTYPE_IPV6: {
-               struct ip6_hdr *ip6;
-
-               m = m_getptr(mp, sizeof(*eh), &hoff);
-               KASSERT(m != NULL && m->m_len - hoff >= sizeof(*ip6));
-               ip6 = (struct ip6_hdr *)(mtod(m, caddr_t) + hoff);
-
-               iphlen = sizeof(*ip6);
-               ipproto = ip6->ip6_nxt;
+       } else if (ext.ip6) {
+               iphlen = sizeof(*ext.ip6);
 
                *type_tucmd_mlhl |= IXGBE_ADVTXD_TUCMD_IPV6;
-               break;
-       }
 #endif
-
-       default:
+       } else {
                return offload;
        }
 
        *vlan_macip_lens |= iphlen;
 
-       switch (ipproto) {
-       case IPPROTO_TCP:
+       if (ext.tcp) {
                *type_tucmd_mlhl |= IXGBE_ADVTXD_TUCMD_L4T_TCP;
                if (ISSET(mp->m_pkthdr.csum_flags, M_TCP_CSUM_OUT)) {
                        *olinfo_status |= IXGBE_TXD_POPTS_TXSM << 8;
                        offload = 1;
                }
-               break;
-       case IPPROTO_UDP:
+       } else if (ext.udp) {
                *type_tucmd_mlhl |= IXGBE_ADVTXD_TUCMD_L4T_UDP;
                if (ISSET(mp->m_pkthdr.csum_flags, M_UDP_CSUM_OUT)) {
                        *olinfo_status |= IXGBE_TXD_POPTS_TXSM << 8;
                        offload = 1;
                }
-               break;
        }
 
        return offload;
Index: dev/pci/if_ixl.c
===================================================================
RCS file: /cvs/src/sys/dev/pci/if_ixl.c,v
retrieving revision 1.86
diff -u -p -r1.86 if_ixl.c
--- dev/pci/if_ixl.c    26 Jan 2023 07:32:39 -0000      1.86
+++ dev/pci/if_ixl.c    31 Jan 2023 21:05:40 -0000
@@ -2784,10 +2784,8 @@ ixl_load_mbuf(bus_dma_tag_t dmat, bus_dm
 static uint64_t
 ixl_tx_setup_offload(struct mbuf *m0)
 {
-       struct mbuf *m;
-       int hoff;
+       struct ether_extracted ext;
        uint64_t hlen;
-       uint8_t ipproto;
        uint64_t offload = 0;
 
        if (ISSET(m0->m_flags, M_VLANTAG)) {
@@ -2800,39 +2798,21 @@ ixl_tx_setup_offload(struct mbuf *m0)
            M_IPV4_CSUM_OUT|M_TCP_CSUM_OUT|M_UDP_CSUM_OUT))
                return (offload);
 
-       switch (ntohs(mtod(m0, struct ether_header *)->ether_type)) {
-       case ETHERTYPE_IP: {
-               struct ip *ip;
-
-               m = m_getptr(m0, ETHER_HDR_LEN, &hoff);
-               KASSERT(m != NULL && m->m_len - hoff >= sizeof(*ip));
-               ip = (struct ip *)(mtod(m, caddr_t) + hoff);
+       ether_extract_headers(m0, &ext);
 
+       if (ext.ip4) {
                offload |= ISSET(m0->m_pkthdr.csum_flags, M_IPV4_CSUM_OUT) ?
                    IXL_TX_DESC_CMD_IIPT_IPV4_CSUM :
                    IXL_TX_DESC_CMD_IIPT_IPV4;
  
-               hlen = ip->ip_hl << 2;
-               ipproto = ip->ip_p;
-               break;
-       }
-
+               hlen = ext.ip4->ip_hl << 2;
 #ifdef INET6
-       case ETHERTYPE_IPV6: {
-               struct ip6_hdr *ip6;
-
-               m = m_getptr(m0, ETHER_HDR_LEN, &hoff);
-               KASSERT(m != NULL && m->m_len - hoff >= sizeof(*ip6));
-               ip6 = (struct ip6_hdr *)(mtod(m, caddr_t) + hoff);
- 
+       } else if (ext.ip6) {
                offload |= IXL_TX_DESC_CMD_IIPT_IPV6;
 
-               hlen = sizeof(*ip6);
-               ipproto = ip6->ip6_nxt;
-               break;
-       }
+               hlen = sizeof(*ext.ip6);
 #endif
-       default:
+       } else {
                panic("CSUM_OUT set for non-IP packet");
                /* NOTREACHED */
        }
@@ -2840,30 +2820,12 @@ ixl_tx_setup_offload(struct mbuf *m0)
        offload |= (ETHER_HDR_LEN >> 1) << IXL_TX_DESC_MACLEN_SHIFT;
        offload |= (hlen >> 2) << IXL_TX_DESC_IPLEN_SHIFT;
 
-       switch (ipproto) {
-       case IPPROTO_TCP: {
-               struct tcphdr *th;
-
-               if (!ISSET(m0->m_pkthdr.csum_flags, M_TCP_CSUM_OUT))
-                       break;
-
-               m = m_getptr(m, hoff + hlen, &hoff);
-               KASSERT(m != NULL && m->m_len - hoff >= sizeof(*th));
-               th = (struct tcphdr *)(mtod(m, caddr_t) + hoff);
- 
+       if (ext.tcp && ISSET(m0->m_pkthdr.csum_flags, M_TCP_CSUM_OUT)) {
                offload |= IXL_TX_DESC_CMD_L4T_EOFT_TCP;
-               offload |= (uint64_t)th->th_off << IXL_TX_DESC_L4LEN_SHIFT;
-               break;
-       }
-
-       case IPPROTO_UDP:
-               if (!ISSET(m0->m_pkthdr.csum_flags, M_UDP_CSUM_OUT))
-                       break;
- 
+               offload |= (uint64_t)ext.tcp->th_off << IXL_TX_DESC_L4LEN_SHIFT;
+       } else if (ext.udp && ISSET(m0->m_pkthdr.csum_flags, M_UDP_CSUM_OUT)) {
                offload |= IXL_TX_DESC_CMD_L4T_EOFT_UDP;
-               offload |= (sizeof(struct udphdr) >> 2) <<
-                   IXL_TX_DESC_L4LEN_SHIFT;
-               break;
+               offload |= (sizeof(*ext.udp) >> 2) << IXL_TX_DESC_L4LEN_SHIFT;
        }
 
        return (offload);
Index: net/if_ethersubr.c
===================================================================
RCS file: /cvs/src/sys/net/if_ethersubr.c,v
retrieving revision 1.286
diff -u -p -r1.286 if_ethersubr.c
--- net/if_ethersubr.c  26 Jan 2023 07:32:40 -0000      1.286
+++ net/if_ethersubr.c  31 Jan 2023 21:24:04 -0000
@@ -98,6 +98,10 @@ didn't get a copy, you may request one f
 #include <netinet/in.h>
 #include <netinet/if_ether.h>
 #include <netinet/ip_ipsp.h>
+#include <netinet/ip.h>
+#include <netinet/ip6.h>
+#include <netinet/tcp.h>
+#include <netinet/udp.h>
 
 #if NBPFILTER > 0
 #include <net/bpf.h>
@@ -1033,4 +1037,67 @@ ether_e64_to_addr(struct ether_addr *ea,
                ea->ether_addr_octet[--i] = e64;
                e64 >>= 8;
        } while (i > 0);
+}
+
+/* Parse different TCP/IP protocol headers for a quick view inside an mbuf. */
+void
+ether_extract_headers(struct mbuf *mp, struct ether_extracted *ext)
+{
+       struct mbuf     *m;
+       uint64_t         hlen;
+       int              hoff;
+       uint8_t          ipproto;
+
+       /* Return NULL if header was not recognized. */
+       memset(ext, 0, sizeof(*ext));
+
+       if (mp->m_len < sizeof(*ext->eh))
+               return;
+
+       ext->eh = mtod(mp, struct ether_header *);
+       switch (ntohs(ext->eh->ether_type)) {
+       case ETHERTYPE_IP:
+               m = m_getptr(mp, sizeof(*ext->eh), &hoff);
+               if (m == NULL || m->m_len - hoff < sizeof(*ext->ip4))
+                       return;
+               ext->ip4 = (struct ip *)(mtod(m, caddr_t) + hoff);
+
+               if (ISSET(ntohs(ext->ip4->ip_off), IP_MF|IP_OFFMASK))
+                       return;
+
+               hlen = ext->ip4->ip_hl << 2;
+               ipproto = ext->ip4->ip_p;
+
+               break;
+#ifdef INET6
+       case ETHERTYPE_IPV6:
+               m = m_getptr(mp, sizeof(*ext->eh), &hoff);
+               if (m == NULL || m->m_len - hoff < sizeof(*ext->ip6))
+                       return;
+               ext->ip6 = (struct ip6_hdr *)(mtod(m, caddr_t) + hoff);
+
+               hlen = sizeof(*ext->ip6);
+               ipproto = ext->ip6->ip6_nxt;
+
+               break;
+#endif
+       default:
+               return;
+       }
+
+       switch (ipproto) {
+       case IPPROTO_TCP:
+               m = m_getptr(m, hoff + hlen, &hoff);
+               if (m == NULL || m->m_len - hoff < sizeof(*ext->tcp))
+                       return;
+               ext->tcp = (struct tcphdr *)(mtod(m, caddr_t) + hoff);
+               break;
+
+       case IPPROTO_UDP:
+               m = m_getptr(m, hoff + hlen, &hoff);
+               if (m == NULL || m->m_len - hoff < sizeof(*ext->udp))
+                       return;
+               ext->udp = (struct udphdr *)(mtod(m, caddr_t) + hoff);
+               break;
+       }
 }
Index: netinet/if_ether.h
===================================================================
RCS file: /cvs/src/sys/netinet/if_ether.h,v
retrieving revision 1.86
diff -u -p -r1.86 if_ether.h
--- netinet/if_ether.h  26 Jan 2023 07:32:40 -0000      1.86
+++ netinet/if_ether.h  31 Jan 2023 21:05:40 -0000
@@ -297,6 +297,18 @@ const struct ether_brport *
 uint64_t       ether_addr_to_e64(const struct ether_addr *);
 void           ether_e64_to_addr(struct ether_addr *, uint64_t);
 
+struct ether_extracted {
+       struct ether_header     *eh;
+       struct ip               *ip4;
+#ifdef INET6
+       struct ip6_hdr          *ip6;
+#endif
+       struct tcphdr           *tcp;
+       struct udphdr           *udp;
+};
+
+void ether_extract_headers(struct mbuf *, struct ether_extracted *);
+
 /*
  * Ethernet multicast address structure.  There is one of these for each
  * multicast address or range of multicast addresses that we are supposed

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