3ff2e0a825
[ Upstream commit 338bb57e4c2a1c2c6fc92f9c0bd35be7587adca7 ]
The TOS value that is returned to user space in the route get reply is
the one with which the lookup was performed ('fl4->flowi4_tos'). This is
fine when the matched route is configured with a TOS as it would not
match if its TOS value did not match the one with which the lookup was
performed.
However, matching on TOS is only performed when the route's TOS is not
zero. It is therefore possible to have the kernel incorrectly return a
non-zero TOS:
# ip link add name dummy1 up type dummy
# ip address add 192.0.2.1/24 dev dummy1
# ip route get 192.0.2.2 tos 0xfc
192.0.2.2 tos 0x1c dev dummy1 src 192.0.2.1 uid 0
cache
Fix by adding a DSCP field to the FIB result structure (inside an
existing 4 bytes hole), populating it in the route lookup and using it
when filling the route get reply.
Output after the patch:
# ip link add name dummy1 up type dummy
# ip address add 192.0.2.1/24 dev dummy1
# ip route get 192.0.2.2 tos 0xfc
192.0.2.2 dev dummy1 src 192.0.2.1 uid 0
cache
Fixes: 1a00fee4ffb2 ("ipv4: Remove rt_key_{src,dst,tos} from struct rtable.")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
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.