This patchset implements the TCP-AO option as described in RFC5925. There is a request from industry to move away from TCP-MD5SIG and it seems the time is right to have a TCP-AO upstreamed. This TCP option is meant to replace the TCP MD5 option and address its shortcomings. Specifically, it provides more secure hashing, key rotation and support for long-lived connections (see the summary of TCP-AO advantages over TCP-MD5 in (1.3) of RFC5925). The patch series starts with six patches that are not specific to TCP-AO but implement a general crypto facility that we thought is useful to eliminate code duplication between TCP-MD5SIG and TCP-AO as well as other crypto users. These six patches are being submitted separately in a different patchset [1]. Including them here will show better the gain in code sharing. Next are 18 patches that implement the actual TCP-AO option, followed by patches implementing selftests. The patch set was written as a collaboration of three authors (in alphabetical order): Dmitry Safonov, Francesco Ruggeri and Salam Noureddine. Additional credits should be given to Prasad Koya, who was involved in early prototyping a few years back. There is also a separate submission done by Leonard Crestez whom we thank for his efforts getting an implementation of RFC5925 submitted for review upstream [2]. This is an independent implementation that makes different design decisions. For example, we chose a similar design to the TCP-MD5SIG implementation and used setsockopt()s to program per-socket keys, avoiding the extra complexity of managing a centralized key database in the kernel. A centralized database in the kernel has dubious benefits since it doesn’t eliminate per-socket setsockopts needed to specify which sockets need TCP-AO and what are the currently preferred keys. It also complicates traffic key caching and preventing deletion of in-use keys. In this implementation, a centralized database of keys can be thought of as living in user space and user applications would have to program those keys on matching sockets. On the server side, the user application programs keys (MKTS in TCP-AO nomenclature) on the listening socket for all peers that are expected to connect. Prefix matching on the peer address is supported. When a peer issues a successful connect, all the MKTs matching the IP address of the peer are copied to the newly created socket. On the active side, when a connect() is issued all MKTs that do not match the peer are deleted from the socket since they will never match the peer. This implementation uses three setsockopt()s for adding, deleting and modifying keys on a socket. All three setsockopt()s have extensive sanity checks that prevent inconsistencies in the keys on a given socket. A getsockopt() is provided to get key information from any given socket. Few things to note about this implementation: - Traffic keys are cached for established connections avoiding the cost of such calculation for each packet received or sent. - Great care has been taken to avoid deleting in-use MKTs as required by the RFC. - Any crypto algorithm supported by the Linux kernel can be used to calculate packet hashes. - Fastopen works with TCP-AO but hasn’t been tested extensively. - Tested for interop with other major networking vendors (on linux-4.19), including testing for key rotation and long lived connections. There are a couple of limitations that we’re aware of, including (but not limited to) the following: - setsockopt(TCP_REPAIR) not supported yet - IPv4-mapped-IPv6 addresses not tested - static key not implemented yet - CONFIG_TCP_AO depends on CONFIG_TCP_MD5SIG - A small window for a race condition exists between accept and key adding/deletion on a listening socket but can be easily overcome by using the getsockopt() to make sure the right keys are there on a newly accepted connection - Key matching by TCP port numbers, peer ranges, asterisks is unsupported as it’s unlikely to be useful [1]: https://lore.kernel.org/all/20220726201600.1715505-1-dima@xxxxxxxxxx/ [2]: https://lore.kernel.org/all/cover.1658815925.git.cdleonard@xxxxxxxxx/ Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Ard Biesheuvel <ardb@xxxxxxxxxx> Cc: Bob Gilligan <gilligan@xxxxxxxxxx> Cc: David Ahern <dsahern@xxxxxxxxxx> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx> Cc: Dmitry Safonov <0x7f454c46@xxxxxxxxx> Cc: Eric Biggers <ebiggers@xxxxxxxxxx> Cc: Eric Dumazet <edumazet@xxxxxxxxxx> Cc: Francesco Ruggeri <fruggeri@xxxxxxxxxx> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Cc: Hideaki YOSHIFUJI <yoshfuji@xxxxxxxxxxxxxx> Cc: Ivan Delalande <colona@xxxxxxxxxx> Cc: Jakub Kicinski <kuba@xxxxxxxxxx> Cc: Leonard Crestez <cdleonard@xxxxxxxxx> Cc: Paolo Abeni <pabeni@xxxxxxxxxx> Cc: Salam Noureddine <noureddine@xxxxxxxxxx> Cc: Shuah Khan <shuah@xxxxxxxxxx> Cc: netdev@xxxxxxxxxxxxxxx Cc: linux-crypto@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Dmitry Safonov (31): crypto: Introduce crypto_pool crypto_pool: Add crypto_pool_reserve_scratch() net/tcp: Separate tcp_md5sig_info allocation into tcp_md5sig_info_add() net/tcp: Disable TCP-MD5 static key on tcp_md5sig_info destruction net/tcp: Use crypto_pool for TCP-MD5 net/ipv6: sr: Switch to using crypto_pool tcp: Add TCP-AO config and structures net/tcp: Introduce TCP_AO setsockopt()s net/tcp: Prevent TCP-MD5 with TCP-AO being set net/tcp: Calculate TCP-AO traffic keys net/tcp: Add TCP-AO sign to outgoing packets net/tcp: Add tcp_parse_auth_options() net/tcp: Add AO sign to RST packets net/tcp: Add TCP-AO sign to twsk net/tcp: Wire TCP-AO to request sockets net/tcp: Sign SYN-ACK segments with TCP-AO net/tcp: Verify inbound TCP-AO signed segments net/tcp: Add TCP-AO segments counters net/tcp: Add TCP-AO SNE support net/tcp: Add tcp_hash_fail() ratelimited logs net/tcp: Ignore specific ICMPs for TCP-AO connections net/tcp: Add option for TCP-AO to (not) hash header net/tcp: Add getsockopt(TCP_AO_GET) net/tcp: Allow asynchronous delete for TCP-AO keys (MKTs) selftests/net: Add TCP-AO library selftests/net: Verify that TCP-AO complies with ignoring ICMPs selftest/net: Add TCP-AO ICMPs accept test selftest/tcp-ao: Add a test for MKT matching selftest/tcp-ao: Add test for TCP-AO add setsockopt() command selftests/tcp-ao: Add TCP-AO + TCP-MD5 + no sign listen socket tests selftests/aolib: Add test/benchmark for removing MKTs crypto/Kconfig | 12 + crypto/Makefile | 1 + crypto/crypto_pool.c | 323 +++ include/crypto/pool.h | 33 + include/linux/sockptr.h | 23 + include/linux/tcp.h | 24 + include/net/dropreason.h | 25 + include/net/seg6_hmac.h | 7 - include/net/tcp.h | 193 +- include/net/tcp_ao.h | 283 +++ include/uapi/linux/snmp.h | 5 + include/uapi/linux/tcp.h | 62 + net/ipv4/Kconfig | 15 +- net/ipv4/Makefile | 1 + net/ipv4/proc.c | 5 + net/ipv4/tcp.c | 191 +- net/ipv4/tcp_ao.c | 1939 +++++++++++++++++ net/ipv4/tcp_input.c | 94 +- net/ipv4/tcp_ipv4.c | 385 +++- net/ipv4/tcp_minisocks.c | 37 +- net/ipv4/tcp_output.c | 188 +- net/ipv6/Kconfig | 2 +- net/ipv6/Makefile | 1 + net/ipv6/seg6.c | 3 - net/ipv6/seg6_hmac.c | 204 +- net/ipv6/tcp_ao.c | 151 ++ net/ipv6/tcp_ipv6.c | 327 ++- tools/testing/selftests/Makefile | 1 + tools/testing/selftests/net/tcp_ao/.gitignore | 2 + tools/testing/selftests/net/tcp_ao/Makefile | 50 + .../selftests/net/tcp_ao/bench-lookups.c | 403 ++++ .../selftests/net/tcp_ao/connect-deny.c | 217 ++ tools/testing/selftests/net/tcp_ao/connect.c | 81 + .../selftests/net/tcp_ao/icmps-accept.c | 1 + .../selftests/net/tcp_ao/icmps-discard.c | 447 ++++ .../testing/selftests/net/tcp_ao/lib/aolib.h | 333 +++ .../selftests/net/tcp_ao/lib/netlink.c | 341 +++ tools/testing/selftests/net/tcp_ao/lib/proc.c | 267 +++ .../testing/selftests/net/tcp_ao/lib/setup.c | 297 +++ tools/testing/selftests/net/tcp_ao/lib/sock.c | 294 +++ .../testing/selftests/net/tcp_ao/lib/utils.c | 30 + .../selftests/net/tcp_ao/setsockopt-closed.c | 191 ++ .../selftests/net/tcp_ao/unsigned-md5.c | 483 ++++ 43 files changed, 7516 insertions(+), 456 deletions(-) create mode 100644 crypto/crypto_pool.c create mode 100644 include/crypto/pool.h create mode 100644 include/net/tcp_ao.h create mode 100644 net/ipv4/tcp_ao.c create mode 100644 net/ipv6/tcp_ao.c create mode 100644 tools/testing/selftests/net/tcp_ao/.gitignore create mode 100644 tools/testing/selftests/net/tcp_ao/Makefile create mode 100644 tools/testing/selftests/net/tcp_ao/bench-lookups.c create mode 100644 tools/testing/selftests/net/tcp_ao/connect-deny.c create mode 100644 tools/testing/selftests/net/tcp_ao/connect.c create mode 120000 tools/testing/selftests/net/tcp_ao/icmps-accept.c create mode 100644 tools/testing/selftests/net/tcp_ao/icmps-discard.c create mode 100644 tools/testing/selftests/net/tcp_ao/lib/aolib.h create mode 100644 tools/testing/selftests/net/tcp_ao/lib/netlink.c create mode 100644 tools/testing/selftests/net/tcp_ao/lib/proc.c create mode 100644 tools/testing/selftests/net/tcp_ao/lib/setup.c create mode 100644 tools/testing/selftests/net/tcp_ao/lib/sock.c create mode 100644 tools/testing/selftests/net/tcp_ao/lib/utils.c create mode 100644 tools/testing/selftests/net/tcp_ao/setsockopt-closed.c create mode 100644 tools/testing/selftests/net/tcp_ao/unsigned-md5.c base-commit: e34cfee65ec891a319ce79797dda18083af33a76 -- 2.37.2
