4b3b45edba
commit c146066ab802 ("ipv4: Don't use ufo handling on later transformed
packets") and commit f89c56ce710a ("ipv6: Don't use ufo handling on
later transformed packets") added a check that 'rt->dst.header_len' isn't
zero in order to skip UFO, but it doesn't include IPcomp in transport mode
where it equals zero.
Packets, after payload compression, may not require further fragmentation,
and if original length exceeds MTU, later compressed packets will be
transmitted incorrectly. This can be reproduced with LTP udp_ipsec.sh test
on veth device with enabled UFO, MTU is 1500 and UDP payload is 2000:
* IPv4 case, offset is wrong + unnecessary fragmentation
udp_ipsec.sh -p comp -m transport -s 2000 &
tcpdump -ni ltp_ns_veth2
...
IP (tos 0x0, ttl 64, id 45203, offset 0, flags [+],
proto Compressed IP (108), length 49)
10.0.0.2 > 10.0.0.1: IPComp(cpi=0x1000)
IP (tos 0x0, ttl 64, id 45203, offset 1480, flags [none],
proto UDP (17), length 21) 10.0.0.2 > 10.0.0.1: ip-proto-17
* IPv6 case, sending small fragments
udp_ipsec.sh -6 -p comp -m transport -s 2000 &
tcpdump -ni ltp_ns_veth2
...
IP6 (flowlabel 0x6b9ba, hlim 64, next-header Compressed IP (108)
payload length: 37) fd00::2 > fd00::1: IPComp(cpi=0x1000)
IP6 (flowlabel 0x6b9ba, hlim 64, next-header Compressed IP (108)
payload length: 21) fd00::2 > fd00::1: IPComp(cpi=0x1000)
Fix it by checking 'rt->dst.xfrm' pointer to 'xfrm_state' struct, skip UFO
if xfrm is set. So the new check will include both cases: IPcomp and IPsec.
Fixes: c146066ab802 ("ipv4: Don't use ufo handling on later transformed packets")
Fixes: f89c56ce710a ("ipv6: Don't use ufo handling on later transformed packets")
Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.