5.15-stable review patch. If anyone has any objections, please let me know.
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From: Andrea Mayer andrea.mayer@uniroma2.it
commit a3bd2102e464202b58d57390a538d96f57ffc361 upstream.
Commit 40867d74c374 ("net: Add l3mdev index to flow struct and avoid oif reset for port devices") adds a new entry (flowi_l3mdev) in the common flow struct used for indicating the l3mdev index for later rule and table matching. The l3mdev_update_flow() has been adapted to properly set the flowi_l3mdev based on the flowi_oif/flowi_iif. In fact, when a valid flowi_iif is supplied to the l3mdev_update_flow(), this function can update the flowi_l3mdev entry only if it has not yet been set (i.e., the flowi_l3mdev entry is equal to 0).
The SRv6 End.DT6 behavior in VRF mode leverages a VRF device in order to force the routing lookup into the associated routing table. This routing operation is performed by seg6_lookup_any_nextop() preparing a flowi6 data structure used by ip6_route_input_lookup() which, in turn, (indirectly) invokes l3mdev_update_flow().
However, seg6_lookup_any_nexthop() does not initialize the new flowi_l3mdev entry which is filled with random garbage data. This prevents l3mdev_update_flow() from properly updating the flowi_l3mdev with the VRF index, and thus SRv6 End.DT6 (VRF mode)/DT46 behaviors are broken.
This patch correctly initializes the flowi6 instance allocated and used by seg6_lookup_any_nexhtop(). Specifically, the entire flowi6 instance is wiped out: in case new entries are added to flowi/flowi6 (as happened with the flowi_l3mdev entry), we should no longer have incorrectly initialized values. As a result of this operation, the value of flowi_l3mdev is also set to 0.
The proposed fix can be tested easily. Starting from the commit referenced in the Fixes, selftests [1],[2] indicate that the SRv6 End.DT6 (VRF mode)/DT46 behaviors no longer work correctly. By applying this patch, those behaviors are back to work properly again.
[1] - tools/testing/selftests/net/srv6_end_dt46_l3vpn_test.sh [2] - tools/testing/selftests/net/srv6_end_dt6_l3vpn_test.sh
Fixes: 40867d74c374 ("net: Add l3mdev index to flow struct and avoid oif reset for port devices") Reported-by: Anton Makarov am@3a-alliance.com Signed-off-by: Andrea Mayer andrea.mayer@uniroma2.it Reviewed-by: David Ahern dsahern@kernel.org Link: https://lore.kernel.org/r/20220608091917.20345-1-andrea.mayer@uniroma2.it Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv6/seg6_local.c | 1 + 1 file changed, 1 insertion(+)
--- a/net/ipv6/seg6_local.c +++ b/net/ipv6/seg6_local.c @@ -217,6 +217,7 @@ seg6_lookup_any_nexthop(struct sk_buff * struct flowi6 fl6; int dev_flags = 0;
+ memset(&fl6, 0, sizeof(fl6)); fl6.flowi6_iif = skb->dev->ifindex; fl6.daddr = nhaddr ? *nhaddr : hdr->daddr; fl6.saddr = hdr->saddr;