The algorithm for checksum neutral mapping is incorrect. This problem
was being hidden since we were previously always performing checksum
offload on the translated addresses and only with IPv6 HW csum.
Enabling an ILA router shows the issue.
Corrected algorithm:
old_loc is the original locator in the packet, new_loc is the value
to overwrite with and is found in the lookup table. old_flag is
the old flag value (zero of CSUM_NEUTRAL_FLAG) and new_flag is
then (old_flag ^ CSUM_NEUTRAL_FLAG) & CSUM_NEUTRAL_FLAG.
Need SUM(new_id + new_flag + diff) == SUM(old_id + old_flag) for
checksum neutral translation.
Solving for diff gives:
diff = (old_id - new_id) + (old_flag - new_flag)
compute_csum_diff8(new_id, old_id) gives old_id - new_id
If old_flag is set
old_flag - new_flag = old_flag = CSUM_NEUTRAL_FLAG
Else
old_flag - new_flag = -new_flag = ~CSUM_NEUTRAL_FLAG
Tested:
- Implemented a user space program that creates random addresses
and random locators to overwrite. Compares the checksum over
the address before and after translation (must always be equal)
- Enabled ILA router and showed proper operation.
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When setting up ILA in a router we noticed that the the encapsulation
is invoked twice: once in the route input path and again upon route
output. To resolve this we add a flag set_csum_neutral for the
ila_update_ipv6_locator. If this flag is set and the checksum
neutral bit is also set we assume that checksum-neutral translation
has already been performed and take no further action. The
flag is set only in ila_output path. The flag is not set for ila_input and
ila_xlat.
Tested:
Used 3 netns to set to emulate a router and two hosts. The router
translates SIR addresses between the two destinations in other two netns.
Verified ping and netperf are functional.
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Support checksum neutral ILA as described in the ILA draft. The low
order 16 bits of the identifier are used to contain the checksum
adjustment value.
The csum-mode parameter is added to described checksum processing. There
are three values:
- adjust transport checksum (previous behavior)
- do checksum neutral mapping
- do nothing
On output the csum-mode in the ila_params is checked and acted on. If
mode is checksum neutral mapping then to mapping and set C-bit.
On input, C-bit is checked. If it is set checksum-netural mapping is
done (regardless of csum-mode in ila params) and C-bit will be cleared.
If it is not set then action in csum-mode is taken.
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add structures for identifiers, locators, and an ila address which
is composed of a locator and identifier and in6_addr can be cast to
it. This includes a three bit type field and enums for the types defined
in ILA I-D.
In ILA lwt don't allow user to set a translation for a non-ILA
address (type of identifier is zero meaning it is an IID). This also
requires that the destination prefix is at least 65 bytes (64
bit locator and first byte of identifier).
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Avoid users having to manually load the module by adding a module
alias allowing it to be autoloaded by the lwt infra.
Signed-off-by: Robert Shearman <rshearma@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch implements an ILA tanslation table. This table can be
configured with identifier to locator mappings, and can be be queried
to resolve a mapping. Queries can be parameterized based on interface,
direction (incoming or outoing), and matching locator. The table is
implemented using rhashtable and is configured via netlink (through
"ip ila .." in iproute).
The table may be used as alternative means to do do ILA tanslations
other than the lw tunnels
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Create ila directory in preparation for supporting other hooks in the
kernel than LWT for doing ILA. This includes:
- Moving ila.c to ila/ila_lwt.c
- Splitting out some common functions into ila_common.c
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
