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* siphash, checksum: Move TBAA explanation to checksum.cDavid Gibson2023-09-301-14/+5
| | | | | | | | | | | | A number of checksum and hash functions require workarounds for the odd behaviour of Type-Baased Alias Analysis. We have a detailed comment about this on siphash_8b() and other functions reference that. Move the main comment to csume_16b() instead, because we're going to reorganise things in siphash.c. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* siphash: Make internal helpers publicDavid Gibson2023-09-301-104/+0
| | | | | | | | | Move a bunch of code from siphash.c to siphash.h, making it available to other modules. This will allow places which need hashes of more complex objects to construct them incrementally. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* siphash: Use specific structure for internal stateDavid Gibson2023-09-301-38/+42
| | | | | | | | To improve type safety, encapsulate the internal state of the SipHash algorithm into a dedicated structure type. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* siphash: Use more hygienic state initialiserDavid Gibson2023-09-301-17/+12
| | | | | | | | | | The PREAMBLE macro sets up the SipHash initial internal state. It also defines that state as a variable, which isn't macro hygeinic. With previous changes simplifying this premable, it's now possible to replace it with a macro which simply expands to a C initialisedrfor that state. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* siphash: Fix bug in state initialisationDavid Gibson2023-09-301-1/+1
| | | | | | | | | | | | | The SipHash algorithm starts with initializing the 32 bytes of internal state with some magic numbers XORed with the hash key. However, our implementation has a bug - rather than XORing the hash key, it *sets* the initial state to copies of the key. I don't know if that affects any of the cryptographic properties of SipHash but it's not what we should be doing. Fix it. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* siphash: Clean up hash finalisation with posthash_final() functionDavid Gibson2023-09-301-30/+28
| | | | | | | | | | | | | | | | | | | | | The POSTAMBLE macro implements the finalisation steps of SipHash. It relies on some variables in the environment, including returning the final hash value that way. That isn't great hygeine. In addition the PREAMBLE macro takes a length parameter which is used only to initialize the 'b' value that's not used until the finalisation and is also sometimes modified in a non-obvious way by the callers. The 'b' value is always composed from the total length of the hash input plus up to 7 bytes of "tail" data - that is the remainder of the hash input after a multiple of 8 bytes has been consumed. Simplify all this by replacing the POSTAMBLE macro with a siphash_final() function which takes the length and tail data as parameters and returns the final hash value. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* siphash: Add siphash_feed() helperDavid Gibson2023-09-301-31/+21
| | | | | | | | | | | | | We have macros or inlines for a number of common operations in the siphash functions. However, in a number of places we still open code feeding another 64-bits of data into the hash function: an xor, followed by 2 rounds of shuffling, followed by another xor. Implement an inline function for this, which results in somewhat shortened code. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* siphash: Make sip round calculations an inline function rather than macroDavid Gibson2023-09-301-22/+29
| | | | | | | | | The SIPROUND(n) macro implements n rounds of SipHash shuffling. It relies on 'v' and '__i' variables being available in the context it's used in which isn't great hygeine. Replace it with an inline function instead. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* siphash: Make siphash functions consistently return 64-bit resultsDavid Gibson2023-09-301-10/+7
| | | | | | | | | | | | | | Some of the siphas_*b() functions return 64-bit results, others 32-bit results, with no obvious pattern. siphash_32b() also appears to do this incorrectly - taking the 64-bit hash value and simply returning it truncated, rather than folding the two halves together. Since SipHash proper is defined to give a 64-bit hash, make all of them return 64-bit results. In the one caller which needs a 32-bit value, tcp_seq_init() do the fold down to 32-bits ourselves. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Relicense to GPL 2.0, or any later versionStefano Brivio2023-04-061-1/+1
| | | | | | | | | | | | | | | | | | | In practical terms, passt doesn't benefit from the additional protection offered by the AGPL over the GPL, because it's not suitable to be executed over a computer network. Further, restricting the distribution under the version 3 of the GPL wouldn't provide any practical advantage either, as long as the passt codebase is concerned, and might cause unnecessary compatibility dilemmas. Change licensing terms to the GNU General Public License Version 2, or any later version, with written permission from all current and past contributors, namely: myself, David Gibson, Laine Stump, Andrea Bolognani, Paul Holzinger, Richard W.M. Jones, Chris Kuhn, Florian Weimer, Giuseppe Scrivano, Stefan Hajnoczi, and Vasiliy Ulyanov. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Disable gcc strict aliasing rules as needed, drop workaroundsStefano Brivio2023-02-271-3/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Recently, commit 4ddbcb9c0c55 ("tcp: Disable optimisations for tcp_hash()") worked around yet another issue we hit with gcc 12 and '-flto -O2': some stores affecting the input data to siphash_20b() were omitted altogether, and tcp_hash() wouldn't get the correct hash for incoming connections. Digging further into this revealed that, at least according to gcc's interpretation of C99 aliasing rules, passing pointers to functions with different types compared to the effective type of the object (for example, a uint8_t pointer to an anonymous struct, as it happens in tcp_hash()), doesn't guarantee that stores are not reordered across the function call. This means that, in general, our checksum and hash functions might not see parts of input data that was intended to be provided by callers. Not even switching from uint8_t to character types, which should be appropriate here, according to C99 (ISO/IEC 9899, TC3, draft N1256), section 6.5, "Expressions", paragraph 7: An object shall have its stored value accessed only by an lvalue expression that has one of the following types: [...] — a character type. does the trick. I guess this is also subject to interpretation: casting passed pointers to character types, and then using those as different types, might still violate (dubious) aliasing rules. Disable gcc strict aliasing rules for potentially affected functions, which, in turn, disables gcc's Type-Based Alias Analysis (TBAA) optimisations based on those function arguments. Drop the existing workarounds. Also the (seemingly?) bogus 'maybe-uninitialized' warning on the tcp_tap_handler() > tcp_hash() > siphash_20b() path goes away with -fno-strict-aliasing on siphash_20b(). Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* tcp: Unify initial sequence number calculation for IPv4 and IPv6David Gibson2022-11-251-0/+1
| | | | | | | | | | | | | tcp_seq_init() has separate paths for IPv4 and IPv6 addresses, which means we will calculate different sequence numbers for IPv4 and equivalent IPv4-mapped IPv6 addresses. Change it to treat these the same by always converting the input address into an inany_addr representation and use that to calculate the sequence number. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Hash IPv4 and IPv4-mapped-IPv6 addresses the sameDavid Gibson2022-11-251-0/+1
| | | | | | | | | | | | | | | | | In the tcp_conn structure, we represent the address with an inany_addr which could be an IPv4 or IPv6 address. However, we have different paths which will calculate different hashes for IPv4 and equivalent IPv4-mapped IPv6 addresses. This will cause problems for some future changes. Make the hash function work the same for these two cases, by taking an inany_addr directly. Since this represents IPv4 and IPv4-mapped IPv6 addresses the same way, it will trivially hash the same for both cases. Callers are changed to construct an inany_addr from whatever they have. Some of that will be elided in later changes. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Mark unused functions for cppcheckDavid Gibson2022-09-291-0/+1
| | | | | | | | | | We have a couple of functions that are unused (for now) by design. Although at least one has a flag so that gcc doesn't warn, cppcheck has its own warnings about this. Add specific inline suppressions for these rather than a blanket suppression in the Makefile. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Add cppcheck target, test, and address resulting warningsStefano Brivio2021-10-211-5/+5
| | | | | | | ...mostly false positives, but a number of very relevant ones too, in tcp_get_sndbuf(), tcp_conn_from_tap(), and siphash PREAMBLE(). Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Address gcc 11 warningsStefano Brivio2021-10-201-0/+3
| | | | | | | | | A mix of unchecked return values, a missing permission mask for open(2) with O_CREAT, and some false positives from -Wstringop-overflow and -Wmaybe-uninitialized. Reported-by: Martin Hauke <mardnh@gmx.de> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* LICENSES: Add license text files, add missing notices, fix SPDX tagsStefano Brivio2021-10-201-3/+3
| | | | | | | | | | SPDX tags don't replace license files. Some notices were missing and some tags were not according to the SPDX specification, too. Now reuse --lint from the REUSE tool (https://reuse.software/) passes. Reported-by: Martin Hauke <mardnh@gmx.de> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Add PASTA mode, major reworkStefano Brivio2021-07-171-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | PASTA (Pack A Subtle Tap Abstraction) provides quasi-native host connectivity to an otherwise disconnected, unprivileged network and user namespace, similarly to slirp4netns. Given that the implementation is largely overlapping with PASST, no separate binary is built: 'pasta' (and 'passt4netns' for clarity) both link to 'passt', and the mode of operation is selected depending on how the binary is invoked. Usage example: $ unshare -rUn # echo $$ 1871759 $ ./pasta 1871759 # From another terminal # udhcpc -i pasta0 2>/dev/null # ping -c1 pasta.pizza PING pasta.pizza (64.190.62.111) 56(84) bytes of data. 64 bytes from 64.190.62.111 (64.190.62.111): icmp_seq=1 ttl=255 time=34.6 ms --- pasta.pizza ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 34.575/34.575/34.575/0.000 ms # ping -c1 spaghetti.pizza PING spaghetti.pizza(2606:4700:3034::6815:147a (2606:4700:3034::6815:147a)) 56 data bytes 64 bytes from 2606:4700:3034::6815:147a (2606:4700:3034::6815:147a): icmp_seq=1 ttl=255 time=29.0 ms --- spaghetti.pizza ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 28.967/28.967/28.967/0.000 ms This entails a major rework, especially with regard to the storage of tracked connections and to the semantics of epoll(7) references. Indexing TCP and UDP bindings merely by socket proved to be inflexible and unsuitable to handle different connection flows: pasta also provides Layer-2 to Layer-2 socket mapping between init and a separate namespace for local connections, using a pair of splice() system calls for TCP, and a recvmmsg()/sendmmsg() pair for UDP local bindings. For instance, building on the previous example: # ip link set dev lo up # iperf3 -s $ iperf3 -c ::1 -Z -w 32M -l 1024k -P2 | tail -n4 [SUM] 0.00-10.00 sec 52.3 GBytes 44.9 Gbits/sec 283 sender [SUM] 0.00-10.43 sec 52.3 GBytes 43.1 Gbits/sec receiver iperf Done. epoll(7) references now include a generic part in order to demultiplex data to the relevant protocol handler, using 24 bits for the socket number, and an opaque portion reserved for usage by the single protocol handlers, in order to track sockets back to corresponding connections and bindings. A number of fixes pertaining to TCP state machine and congestion window handling are also included here. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Add siphash implementation for initial sequence numbersStefano Brivio2021-03-171-0/+217
Implement siphash routines for initial TCP sequence numbers (12 bytes input for IPv4, 36 bytes input for IPv6), and while at it, also functions we'll use later on for hash table indices and TCP timestamp offsets (with 8, 20, 32 bytes of input). Use these to set the initial sequence number, according to RFC 6528, for connections originating either from the tap device or from sockets. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>