kernel/linux.git/net/ipv6/exthdrs.c, branch linux-4.16.y

ipv6: sr: fix TLVs not being copied using setsockopt

2018-01-10T21:03:55+00:00

Function ipv6_push_rthdr4 allows to add an IPv6 Segment Routing Header to a socket through setsockopt, but the current implementation doesn't copy possible TLVs at the end of the SRH received from userspace. Therefore, the execution of the following branch if (sr_has_hmac(sr_phdr)) { ... } will never complete since the len and type fields of a possible HMAC TLV are not copied, hence seg6_get_tlv_hmac will return an error, and the HMAC will not be computed. This commit adds a memcpy in case TLVs have been appended to the SRH. Fixes: a149e7c7ce81 ("ipv6: sr: add support for SRH injection through setsockopt") Acked-by: David Lebrun Signed-off-by: Mathieu Xhonneux Signed-off-by: David S. Miller

ipv6: Implement limits on Hop-by-Hop and Destination options

2017-11-03T00:50:22+00:00

RFC 8200 (IPv6) defines Hop-by-Hop options and Destination options extension headers. Both of these carry a list of TLVs which is only limited by the maximum length of the extension header (2048 bytes). By the spec a host must process all the TLVs in these options, however these could be used as a fairly obvious denial of service attack. I think this could in fact be a significant DOS vector on the Internet, one mitigating factor might be that many FWs drop all packets with EH (and obviously this is only IPv6) so an Internet wide attack might not be so effective (yet!). By my calculation, the worse case packet with TLVs in a standard 1500 byte MTU packet that would be processed by the stack contains 1282 invidual TLVs (including pad TLVS) or 724 two byte TLVs. I wrote a quick test program that floods a whole bunch of these packets to a host and sure enough there is substantial time spent in ip6_parse_tlv. These packets contain nothing but unknown TLVS (that are ignored), TLV padding, and bogus UDP header with zero payload length. 25.38% [kernel] [k] __fib6_clean_all 21.63% [kernel] [k] ip6_parse_tlv 4.21% [kernel] [k] __local_bh_enable_ip 2.18% [kernel] [k] ip6_pol_route.isra.39 1.98% [kernel] [k] fib6_walk_continue 1.88% [kernel] [k] _raw_write_lock_bh 1.65% [kernel] [k] dst_release This patch adds configurable limits to Destination and Hop-by-Hop options. There are three limits that may be set: - Limit the number of options in a Hop-by-Hop or Destination options extension header. - Limit the byte length of a Hop-by-Hop or Destination options extension header. - Disallow unrecognized options in a Hop-by-Hop or Destination options extension header. The limits are set in corresponding sysctls: ipv6.sysctl.max_dst_opts_cnt ipv6.sysctl.max_hbh_opts_cnt ipv6.sysctl.max_dst_opts_len ipv6.sysctl.max_hbh_opts_len If a max_*_opts_cnt is less than zero then unknown TLVs are disallowed. The number of known TLVs that are allowed is the absolute value of this number. If a limit is exceeded when processing an extension header the packet is dropped. Default values are set to 8 for options counts, and set to INT_MAX for maximum length. Note the choice to limit options to 8 is an arbitrary guess (roughly based on the fact that the stack supports three HBH options and just one destination option). These limits have being proposed in draft-ietf-6man-rfc6434-bis. Tested (by Martin Lau) I tested out 1 thread (i.e. one raw_udp process). I changed the net.ipv6.max_dst_(opts|hbh)_number between 8 to 2048. With sysctls setting to 2048, the softirq% is packed to 100%. With 8, the softirq% is almost unnoticable from mpstat. v2; - Code and documention cleanup. - Change references of RFC2460 to be RFC8200. - Add reference to RFC6434-bis where the limits will be in standard. Signed-off-by: Tom Herbert Signed-off-by: David S. Miller

ipv6: exthdrs: use swap macro in ipv6_dest_hao

2017-10-28T10:06:59+00:00

make use of the swap macro and remove unnecessary variable tmp_addr. This makes the code easier to read and maintain. This code was detected with the help of Coccinelle. Signed-off-by: Gustavo A. R. Silva Signed-off-by: David S. Miller

ipv6: mark expected switch fall-throughs

2017-10-18T13:13:08+00:00

In preparation to enabling -Wimplicit-fallthrough, mark switch cases where we are expecting to fall through. Notice that in some cases I placed the "fall through" comment on its own line, which is what GCC is expecting to find. Signed-off-by: Gustavo A. R. Silva Signed-off-by: David S. Miller

ipv6: sr: allow SRH insertion with arbitrary segments_left value

2017-08-07T21:16:21+00:00

The seg6_validate_srh() function only allows SRHs whose active segment is the first segment of the path. However, an application may insert an SRH whose active segment is not the first one. Such an application might be for example an SR-aware Virtual Network Function. This patch enables to insert SRHs with an arbitrary active segment. Signed-off-by: David Lebrun Signed-off-by: David S. Miller

udp6: fix jumbogram reception

2017-08-01T05:01:21+00:00

Since commit 67a51780aebb ("ipv6: udp: leverage scratch area helpers") udp6_recvmsg() read the skb len from the scratch area, to avoid a cache miss. But the UDP6 rx path support RFC 2675 UDPv6 jumbograms, and their length exceeds the 16 bits available in the scratch area. As a side effect the length returned by recvmsg() is: % (1<<16) This commit addresses the issue allocating one more bit in the IP6CB flags field and setting it for incoming jumbograms. Such field is still in the first cacheline, so at recvmsg() time we can check it and fallback to access skb->len if required, without a measurable overhead. Fixes: 67a51780aebb ("ipv6: udp: leverage scratch area helpers") Signed-off-by: Paolo Abeni Signed-off-by: David S. Miller

net, ipv6: convert ipv6_txoptions.refcnt from atomic_t to refcount_t

2017-07-04T08:29:03+00:00

refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. Signed-off-by: Elena Reshetova Signed-off-by: Hans Liljestrand Signed-off-by: Kees Cook Signed-off-by: David Windsor Signed-off-by: David S. Miller

networking: make skb_push & __skb_push return void pointers

2017-06-16T15:48:40+00:00

It seems like a historic accident that these return unsigned char *, and in many places that means casts are required, more often than not. Make these functions return void * and remove all the casts across the tree, adding a (u8 *) cast only where the unsigned char pointer was used directly, all done with the following spatch: @@ expression SKB, LEN; typedef u8; identifier fn = { skb_push, __skb_push, skb_push_rcsum }; @@ - *(fn(SKB, LEN)) + *(u8 *)fn(SKB, LEN) @@ expression E, SKB, LEN; identifier fn = { skb_push, __skb_push, skb_push_rcsum }; type T; @@ - E = ((T *)(fn(SKB, LEN))) + E = fn(SKB, LEN) @@ expression SKB, LEN; identifier fn = { skb_push, __skb_push, skb_push_rcsum }; @@ - fn(SKB, LEN)[0] + *(u8 *)fn(SKB, LEN) Note that the last part there converts from push(...)[0] to the more idiomatic *(u8 *)push(...). Signed-off-by: Johannes Berg Signed-off-by: David S. Miller

ipv6: Need to export ipv6_push_frag_opts for tunneling now.

2017-05-01T19:10:20+00:00

Since that change also made the nfrag function not necessary for exports, remove it. Fixes: 89a23c8b528b ("ip6_tunnel: Fix missing tunnel encapsulation limit option") Signed-off-by: David S. Miller

ipv6: fix source routing

2017-04-25T17:59:24+00:00

Commit a149e7c7ce81 ("ipv6: sr: add support for SRH injection through setsockopt") introduced handling of IPV6_SRCRT_TYPE_4, but at the same time restricted it to only IPV6_SRCRT_TYPE_0 and IPV6_SRCRT_TYPE_4. Previously, ipv6_push_exthdr() and fl6_update_dst() would also handle other values (ie STRICT and TYPE_2). Restore previous source routing behavior, by handling IPV6_SRCRT_STRICT and IPV6_SRCRT_TYPE_2 the same way as IPV6_SRCRT_TYPE_0 in ipv6_push_exthdr() and fl6_update_dst(). Fixes: a149e7c7ce81 ("ipv6: sr: add support for SRH injection through setsockopt") Signed-off-by: Sabrina Dubroca Reviewed-by: Hannes Frederic Sowa Signed-off-by: David S. Miller