.TH "Kernel API" 9 "enum skb_drop_reason" "May 2022" "API Manual" LINUX
.SH NAME
enum skb_drop_reason \- the reasons of skb drops
.SH SYNOPSIS
enum skb_drop_reason {
.br
.BI "    SKB_NOT_DROPPED_YET"
, 
.br
.br
.BI "    SKB_DROP_REASON_NOT_SPECIFIED"
, 
.br
.br
.BI "    SKB_DROP_REASON_NO_SOCKET"
, 
.br
.br
.BI "    SKB_DROP_REASON_PKT_TOO_SMALL"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_CSUM"
, 
.br
.br
.BI "    SKB_DROP_REASON_SOCKET_FILTER"
, 
.br
.br
.BI "    SKB_DROP_REASON_UDP_CSUM"
, 
.br
.br
.BI "    SKB_DROP_REASON_NETFILTER_DROP"
, 
.br
.br
.BI "    SKB_DROP_REASON_OTHERHOST"
, 
.br
.br
.BI "    SKB_DROP_REASON_IP_CSUM"
, 
.br
.br
.BI "    SKB_DROP_REASON_IP_INHDR"
, 
.br
.br
.BI "    SKB_DROP_REASON_IP_RPFILTER"
, 
.br
.br
.BI "    SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST"
, 
.br
.br
.BI "    SKB_DROP_REASON_XFRM_POLICY"
, 
.br
.br
.BI "    SKB_DROP_REASON_IP_NOPROTO"
, 
.br
.br
.BI "    SKB_DROP_REASON_SOCKET_RCVBUFF"
, 
.br
.br
.BI "    SKB_DROP_REASON_PROTO_MEM"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_MD5NOTFOUND"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_MD5UNEXPECTED"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_MD5FAILURE"
, 
.br
.br
.BI "    SKB_DROP_REASON_SOCKET_BACKLOG"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_FLAGS"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_ZEROWINDOW"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_OLD_DATA"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_OVERWINDOW"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_OFOMERGE"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_RFC7323_PAWS"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_INVALID_SEQUENCE"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_RESET"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_INVALID_SYN"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_CLOSE"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_FASTOPEN"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_OLD_ACK"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_TOO_OLD_ACK"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_ACK_UNSENT_DATA"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_OFO_QUEUE_PRUNE"
, 
.br
.br
.BI "    SKB_DROP_REASON_TCP_OFO_DROP"
, 
.br
.br
.BI "    SKB_DROP_REASON_IP_OUTNOROUTES"
, 
.br
.br
.BI "    SKB_DROP_REASON_BPF_CGROUP_EGRESS"
, 
.br
.br
.BI "    SKB_DROP_REASON_IPV6DISABLED"
, 
.br
.br
.BI "    SKB_DROP_REASON_NEIGH_CREATEFAIL"
, 
.br
.br
.BI "    SKB_DROP_REASON_NEIGH_FAILED"
, 
.br
.br
.BI "    SKB_DROP_REASON_NEIGH_QUEUEFULL"
, 
.br
.br
.BI "    SKB_DROP_REASON_NEIGH_DEAD"
, 
.br
.br
.BI "    SKB_DROP_REASON_TC_EGRESS"
, 
.br
.br
.BI "    SKB_DROP_REASON_QDISC_DROP"
, 
.br
.br
.BI "    SKB_DROP_REASON_CPU_BACKLOG"
, 
.br
.br
.BI "    SKB_DROP_REASON_XDP"
, 
.br
.br
.BI "    SKB_DROP_REASON_TC_INGRESS"
, 
.br
.br
.BI "    SKB_DROP_REASON_UNHANDLED_PROTO"
, 
.br
.br
.BI "    SKB_DROP_REASON_SKB_CSUM"
, 
.br
.br
.BI "    SKB_DROP_REASON_SKB_GSO_SEG"
, 
.br
.br
.BI "    SKB_DROP_REASON_SKB_UCOPY_FAULT"
, 
.br
.br
.BI "    SKB_DROP_REASON_DEV_HDR"
, 
.br
.br
.BI "    SKB_DROP_REASON_DEV_READY"
, 
.br
.br
.BI "    SKB_DROP_REASON_FULL_RING"
, 
.br
.br
.BI "    SKB_DROP_REASON_NOMEM"
, 
.br
.br
.BI "    SKB_DROP_REASON_HDR_TRUNC"
, 
.br
.br
.BI "    SKB_DROP_REASON_TAP_FILTER"
, 
.br
.br
.BI "    SKB_DROP_REASON_TAP_TXFILTER"
, 
.br
.br
.BI "    SKB_DROP_REASON_ICMP_CSUM"
, 
.br
.br
.BI "    SKB_DROP_REASON_INVALID_PROTO"
, 
.br
.br
.BI "    SKB_DROP_REASON_IP_INADDRERRORS"
, 
.br
.br
.BI "    SKB_DROP_REASON_IP_INNOROUTES"
, 
.br
.br
.BI "    SKB_DROP_REASON_PKT_TOO_BIG"
, 
.br
.br
.BI "    SKB_DROP_REASON_MAX"

};
.SH Constants
.IP "SKB_NOT_DROPPED_YET" 12
skb is not dropped yet (used for no-drop case)
.IP "SKB_DROP_REASON_NOT_SPECIFIED" 12
drop reason is not specified
.IP "SKB_DROP_REASON_NO_SOCKET" 12
socket not found
.IP "SKB_DROP_REASON_PKT_TOO_SMALL" 12
packet size is too small
.IP "SKB_DROP_REASON_TCP_CSUM" 12
TCP checksum error
.IP "SKB_DROP_REASON_SOCKET_FILTER" 12
dropped by socket filter
.IP "SKB_DROP_REASON_UDP_CSUM" 12
UDP checksum error
.IP "SKB_DROP_REASON_NETFILTER_DROP" 12
dropped by netfilter
.IP "SKB_DROP_REASON_OTHERHOST" 12
packet don't belong to current host
(interface is in promisc mode)
.IP "SKB_DROP_REASON_IP_CSUM" 12
IP checksum error
.IP "SKB_DROP_REASON_IP_INHDR" 12
there is something wrong with IP header (see
IPSTATS_MIB_INHDRERRORS)
.IP "SKB_DROP_REASON_IP_RPFILTER" 12
IP rpfilter validate failed. see the
document for rp_filter in ip-sysctl.rst for more information
.IP "SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST" 12
destination address of L2 is
multicast, but L3 is unicast.
.IP "SKB_DROP_REASON_XFRM_POLICY" 12
xfrm policy check failed
.IP "SKB_DROP_REASON_IP_NOPROTO" 12
no support for IP protocol
.IP "SKB_DROP_REASON_SOCKET_RCVBUFF" 12
socket receive buff is full
.IP "SKB_DROP_REASON_PROTO_MEM" 12
proto memory limition, such as udp packet
drop out of udp_memory_allocated.
.IP "SKB_DROP_REASON_TCP_MD5NOTFOUND" 12
no MD5 hash and one expected,
corresponding to LINUX_MIB_TCPMD5NOTFOUND
.IP "SKB_DROP_REASON_TCP_MD5UNEXPECTED" 12
MD5 hash and we're not expecting
one, corresponding to LINUX_MIB_TCPMD5UNEXPECTED
.IP "SKB_DROP_REASON_TCP_MD5FAILURE" 12
MD5 hash and its wrong, corresponding
to LINUX_MIB_TCPMD5FAILURE
.IP "SKB_DROP_REASON_SOCKET_BACKLOG" 12
failed to add skb to socket backlog (
see LINUX_MIB_TCPBACKLOGDROP)
.IP "SKB_DROP_REASON_TCP_FLAGS" 12
TCP flags invalid
.IP "SKB_DROP_REASON_TCP_ZEROWINDOW" 12
TCP receive window size is zero,
see LINUX_MIB_TCPZEROWINDOWDROP
.IP "SKB_DROP_REASON_TCP_OLD_DATA" 12
the TCP data reveived is already
received before (spurious retrans may happened), see
LINUX_MIB_DELAYEDACKLOST
.IP "SKB_DROP_REASON_TCP_OVERWINDOW" 12
the TCP data is out of window,
the seq of the first byte exceed the right edges of receive
window
.IP "SKB_DROP_REASON_TCP_OFOMERGE" 12
the data of skb is already in the ofo
queue, corresponding to LINUX_MIB_TCPOFOMERGE
.IP "SKB_DROP_REASON_TCP_RFC7323_PAWS" 12
PAWS check, corresponding to
LINUX_MIB_PAWSESTABREJECTED
.IP "SKB_DROP_REASON_TCP_INVALID_SEQUENCE" 12
Not acceptable SEQ field
.IP "SKB_DROP_REASON_TCP_RESET" 12
Invalid RST packet
.IP "SKB_DROP_REASON_TCP_INVALID_SYN" 12
Incoming packet has unexpected SYN flag
.IP "SKB_DROP_REASON_TCP_CLOSE" 12
TCP socket in CLOSE state
.IP "SKB_DROP_REASON_TCP_FASTOPEN" 12
dropped by FASTOPEN request socket
.IP "SKB_DROP_REASON_TCP_OLD_ACK" 12
TCP ACK is old, but in window
.IP "SKB_DROP_REASON_TCP_TOO_OLD_ACK" 12
TCP ACK is too old
.IP "SKB_DROP_REASON_TCP_ACK_UNSENT_DATA" 12
TCP ACK for data we haven't sent yet
.IP "SKB_DROP_REASON_TCP_OFO_QUEUE_PRUNE" 12
pruned from TCP OFO queue
.IP "SKB_DROP_REASON_TCP_OFO_DROP" 12
data already in receive queue
.IP "SKB_DROP_REASON_IP_OUTNOROUTES" 12
route lookup failed
.IP "SKB_DROP_REASON_BPF_CGROUP_EGRESS" 12
dropped by BPF_PROG_TYPE_CGROUP_SKB
eBPF program
.IP "SKB_DROP_REASON_IPV6DISABLED" 12
IPv6 is disabled on the device
.IP "SKB_DROP_REASON_NEIGH_CREATEFAIL" 12
failed to create neigh entry
.IP "SKB_DROP_REASON_NEIGH_FAILED" 12
neigh entry in failed state
.IP "SKB_DROP_REASON_NEIGH_QUEUEFULL" 12
arp_queue for neigh entry is full
.IP "SKB_DROP_REASON_NEIGH_DEAD" 12
neigh entry is dead
.IP "SKB_DROP_REASON_TC_EGRESS" 12
dropped in TC egress HOOK
.IP "SKB_DROP_REASON_QDISC_DROP" 12
dropped by qdisc when packet outputting (
failed to enqueue to current qdisc)
.IP "SKB_DROP_REASON_CPU_BACKLOG" 12
failed to enqueue the skb to the per CPU
backlog queue. This can be caused by backlog queue full (see
netdev_max_backlog in net.rst) or RPS flow limit
.IP "SKB_DROP_REASON_XDP" 12
dropped by XDP in input path
.IP "SKB_DROP_REASON_TC_INGRESS" 12
dropped in TC ingress HOOK
.IP "SKB_DROP_REASON_UNHANDLED_PROTO" 12
protocol not implemented or not supported
.IP "SKB_DROP_REASON_SKB_CSUM" 12
sk_buff checksum computation error
.IP "SKB_DROP_REASON_SKB_GSO_SEG" 12
gso segmentation error
.IP "SKB_DROP_REASON_SKB_UCOPY_FAULT" 12
failed to copy data from user space,
e.g., via \fBzerocopy_sg_from_iter\fP or \fBskb_orphan_frags_rx\fP
.IP "SKB_DROP_REASON_DEV_HDR" 12
device driver specific header/metadata is invalid
.IP "SKB_DROP_REASON_DEV_READY" 12
the device is not ready to xmit/recv due to
any of its data structure that is not up/ready/initialized,
e.g., the IFF_UP is not set, or driver specific tun->tfiles[txq]
is not initialized
.IP "SKB_DROP_REASON_FULL_RING" 12
ring buffer is full
.IP "SKB_DROP_REASON_NOMEM" 12
error due to OOM
.IP "SKB_DROP_REASON_HDR_TRUNC" 12
failed to trunc/extract the header from
networking data, e.g., failed to pull the protocol header from
frags via \fBpskb_may_pull\fP
.IP "SKB_DROP_REASON_TAP_FILTER" 12
dropped by (ebpf) filter directly attached
to tun/tap, e.g., via TUNSETFILTEREBPF
.IP "SKB_DROP_REASON_TAP_TXFILTER" 12
dropped by tx filter implemented at
tun/tap, e.g., \fBcheck_filter\fP
.IP "SKB_DROP_REASON_ICMP_CSUM" 12
ICMP checksum error
.IP "SKB_DROP_REASON_INVALID_PROTO" 12
the packet doesn't follow RFC 2211,
such as a broadcasts ICMP_TIMESTAMP
.IP "SKB_DROP_REASON_IP_INADDRERRORS" 12
host unreachable, corresponding to
IPSTATS_MIB_INADDRERRORS
.IP "SKB_DROP_REASON_IP_INNOROUTES" 12
network unreachable, corresponding to
IPSTATS_MIB_INADDRERRORS
.IP "SKB_DROP_REASON_PKT_TOO_BIG" 12
packet size is too big (maybe exceed the
MTU)
.IP "SKB_DROP_REASON_MAX" 12
the maximum of drop reason, which shouldn't be
used as a real 'reason'
.SH "Description"
The reason of skb drop, which is used in \fBkfree_skb_reason\fP.
en...maybe they should be splited by group?