BMC/Intel-BMC/linux.git/net/mpls, branch v4.4

mpls: make via address optional for multipath routes

2015-12-12T05:43:44+00:00

The via address is optional for a single path route, yet is mandatory when the multipath attribute is used: # ip -f mpls route add 100 dev lo # ip -f mpls route add 101 nexthop dev lo RTNETLINK answers: Invalid argument Make them consistent by making the via address optional when the RTA_MULTIPATH attribute is being parsed so that both forms of specifying the route work. Signed-off-by: Robert Shearman Signed-off-by: David S. Miller

mpls: fix out-of-bounds access when via address not specified

2015-12-12T05:43:44+00:00

When a via address isn't specified, the via table is left initialised to 0 (NEIGH_ARP_TABLE), and the via address length also left initialised to 0. This results in a via address array of length 0 being allocated (contiguous with route and nexthop array), meaning that when a packet is sent using neigh_xmit the neighbour lookup and creation will cause an out-of-bounds access when accessing the 4 bytes of the IPv4 address it assumes it has been given a pointer to. This could be fixed by allocating the 4 bytes of via address necessary and leaving it as all zeroes. However, it seems wrong to me to use an ipv4 nexthop (including possibly ARPing for 0.0.0.0) when the user didn't specify to do so. Instead, set the via address table to NEIGH_NR_TABLES to signify it hasn't been specified and use this at forwarding time to signify a neigh_xmit using an L2 address consisting of the device address. This mechanism is the same as that used for both ARP and ND for loopback interfaces and those flagged as no-arp, which are all we can really support in this case. Fixes: cf4b24f0024f ("mpls: reduce memory usage of routes") Signed-off-by: Robert Shearman Signed-off-by: David S. Miller

mpls: don't dump RTA_VIA attribute if not specified

2015-12-12T05:43:44+00:00

The problem seen is that when adding a route with a nexthop with no via address specified, iproute2 generates bogus output: # ip -f mpls route add 100 dev lo # ip -f mpls route list 100 via inet 0.0.8.0 dev lo The reason for this is that the kernel generates an RTA_VIA attribute with the family set to AF_INET, but the via address data having zero length. The cause of family being AF_INET is that on route insert cfg->rc_via_table is left set to 0, which just happens to be NEIGH_ARP_TABLE which is then translated into AF_INET. iproute2 doesn't validate the length prior to printing and so prints garbage. Although it could be fixed to do the validation, I would argue that AF_INET addresses should always be exactly 4 bytes so the kernel is really giving userspace bogus data. Therefore, avoid generating the RTA_VIA attribute when dumping the route if the via address wasn't specified on add/modify. This is indicated by NEIGH_ARP_TABLE and a zero via address length - if the user specified a via address the address length would have been validated such that it was 4 bytes. Although this is a change in behaviour that is visible to userspace, I believe that what was generated before was invalid and as such userspace wouldn't be expecting it. Signed-off-by: Robert Shearman Signed-off-by: David S. Miller

mpls: validate L2 via address length

2015-12-12T05:43:44+00:00

If an L2 via address for an mpls nexthop is specified, the length of the L2 address must match that expected by the output device, otherwise it could access memory beyond the end of the via address buffer in the route. This check was present prior to commit f8efb73c97e2 ("mpls: multipath route support"), but got lost in the refactoring, so add it back, applying it to all nexthops in multipath routes. Fixes: f8efb73c97e2 ("mpls: multipath route support") Signed-off-by: Robert Shearman Acked-by: Roopa Prabhu Signed-off-by: David S. Miller

mpls: fix sending of local encapped packets

2015-12-07T21:32:47+00:00

Locally generated IPv4 and (probably) IPv6 packets are dropped because skb->protocol isn't set. We could write wrappers to lwtunnel_output for IPv4 and IPv6 that set the protocol accordingly and then call lwtunnel_output, but mpls_output relies on the AF-specific type of dst anyway to get the via address. Therefore, make use of dst->dst_ops->family in mpls_output to determine the type of nexthop and thus protocol of the packet instead of checking skb->protocol. Fixes: 61adedf3e3f1 ("route: move lwtunnel state to dst_entry") Reported-by: Sam Russell Signed-off-by: Robert Shearman Signed-off-by: David S. Miller

mpls: reduce memory usage of routes

2015-10-28T02:52:59+00:00

Nexthops for MPLS routes have a via address field sized for the largest via address that is expected, which is 32 bytes. This means that in the most common case of having ipv4 via addresses, 28 bytes of memory more than required are used per nexthop. In the other common case of an ipv6 nexthop then 16 bytes more than required are used. With large numbers of MPLS routes this extra memory usage could start to become significant. To avoid allocating memory for a maximum length via address when not all of it is required and to allow for ease of iterating over nexthops, then the via addresses are changed to be stored in the same memory block as the route and nexthops, but in an array after the end of the array of nexthops. New accessors are provided to retrieve a pointer to the via address. To allow for O(1) access without having to store a pointer or offset per nh, the via address for each nexthop is sized according to the maximum via address for any nexthop in the route, which is stored in a new route field, rt_max_alen, but this is in an existing hole in struct mpls_route so it doesn't increase the size of the structure. Each via address is ensured to be aligned to VIA_ALEN_ALIGN to account for architectures that don't allow unaligned accesses. Signed-off-by: Robert Shearman Signed-off-by: David S. Miller

mpls: fix forwarding using v4/v6 explicit null

2015-10-28T02:52:58+00:00

Fill in the via address length for the predefined IPv4 and IPv6 explicit-null label routes. Fixes: f8efb73c97e2 ("mpls: multipath route support") Signed-off-by: Robert Shearman Acked-by: Roopa Prabhu Signed-off-by: David S. Miller

mpls: flow-based multipath selection

2015-10-23T13:26:45+00:00

Change the selection of a multipath route to use a flow-based hash. This more suitable for traffic sensitive to reordering within a flow (e.g. TCP, L2VPN) and whilst still allowing a good distribution of traffic given enough flows. Selection of the path for a multipath route is done using a hash of: 1. Label stack up to MAX_MP_SELECT_LABELS labels or up to and including entropy label, whichever is first. 2. 3-tuple of (L3 src, L3 dst, proto) from IPv4/IPv6 header in MPLS payload, if present. Naturally, a 5-tuple hash using L4 information in addition would be possible and be better in some scenarios, but there is a tradeoff between looking deeper into the packet to achieve good distribution, and packet forwarding performance, and I have erred on the side of the latter as the default. Signed-off-by: Robert Shearman Signed-off-by: Roopa Prabhu Signed-off-by: David S. Miller

mpls: multipath route support

2015-10-23T13:26:42+00:00

This patch adds support for MPLS multipath routes. Includes following changes to support multipath: - splits struct mpls_route into 'struct mpls_route + struct mpls_nh' - 'struct mpls_nh' represents a mpls nexthop label forwarding entry - moves mpls route and nexthop structures into internal.h - A mpls_route can point to multiple mpls_nh structs - the nexthops are maintained as a array (similar to ipv4 fib) - In the process of restructuring, this patch also consistently changes all labels to u8 - Adds support to parse/fill RTA_MULTIPATH netlink attribute for multipath routes similar to ipv4/v6 fib - In this patch, the multipath route nexthop selection algorithm simply returns the first nexthop. It is replaced by a hash based algorithm from Robert Shearman in the next patch - mpls_route_update cleanup: remove 'dev' handling in mpls_route_update. mpls_route_update though implemented to update based on dev, it was never used that way. And the dev handling gets tricky with multiple nexthops. Cannot match against any single nexthops dev. So, this patch removes the unused 'dev' handling in mpls_route_update. - dead route/path handling will be implemented in a subsequent patch Example: $ip -f mpls route add 100 nexthop as 200 via inet 10.1.1.2 dev swp1 \ nexthop as 700 via inet 10.1.1.6 dev swp2 \ nexthop as 800 via inet 40.1.1.2 dev swp3 $ip -f mpls route show 100 nexthop as to 200 via inet 10.1.1.2 dev swp1 nexthop as to 700 via inet 10.1.1.6 dev swp2 nexthop as to 800 via inet 40.1.1.2 dev swp3 Signed-off-by: Roopa Prabhu Acked-by: Robert Shearman Signed-off-by: David S. Miller

dst: Pass net into dst->output

2015-10-08T11:27:03+00:00

The network namespace is already passed into dst_output pass it into dst->output lwt->output and friends. Signed-off-by: "Eric W. Biederman" Signed-off-by: David S. Miller