I noticed when I added support for IPV6_DONTFRAG that if you set
IPV6_RECVERR and tried to send a UDP packet larger than 64K to an
IPv6 destination, you'd correctly get an EMSGSIZE, but reading from
MSG_ERRQUEUE returned the incorrect address in the cmsg:
struct msghdr:
msg_name 0x7fff8f3c96d0
msg_namelen 28
struct sockaddr_in6:
sin6_family 10
sin6_port 7639
sin6_flowinfo 0
sin6_addr ::ffff:38.32.0.0
sin6_scope_id 0 ((null))
It should have returned this in my case:
struct msghdr:
msg_name 0x7fffd866b510
msg_namelen 28
struct sockaddr_in6:
sin6_family 10
sin6_port 7639
sin6_flowinfo 0
sin6_addr 2620:0:a09:e000:21f:29ff:fe57:f88b
sin6_scope_id 0 ((null))
The problem is that ipv6_recv_error() assumes that if the error
wasn't generated by ICMPv6, it's an IPv4 address sitting there,
and proceeds to create a v4-mapped address from it.
Change ipv6_icmp_error() and ipv6_local_error() to set skb->protocol
to htons(ETH_P_IPV6) so that ipv6_recv_error() knows the address
sitting right after the extended error is IPv6, else it will
incorrectly map the first octet into an IPv4-mapped IPv6 address
in the cmsg structure returned in a recvmsg() call to obtain
the error.
Signed-off-by: Brian Haley <brian.haley@hp.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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