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* treewide: Add IN4ADDR_ANY_INIT macroDavid Gibson2023-12-271-0/+3
| | | | | | | | | | We already define IN4ADDR_LOOPBACK_INIT to initialise a struct in_addr to the loopback address, make a similar one for the unspecified / any address. This avoids messying things with the internal structure of struct in_addr where we don't care about it. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Switch hash table to linear probing instead of chainingDavid Gibson2023-12-271-0/+28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently we deal with hash collisions by letting a hash bucket contain multiple entries, forming a linked list using an index in the connection structure. That's a pretty standard and simple approach, but in our case we can use an even simpler one: linear probing. Here if a hash bucket is occupied we just move onto the next one until we find a feww one. This slightly simplifies lookup and more importantly saves some precious bytes in the connection structure by removing the need for a link. It does require some additional complexity for hash removal. This approach can perform poorly with hash table load is high. However, we already size our hash table of pointers larger than the connection table, which puts an upper bound on the load. It's relatively cheap to decrease that bound if we find we need to. I adapted the linear probing operations from Knuth's The Art of Computer Programming, Volume 3, 2nd Edition. Specifically Algorithm L and Algorithm R in Section 6.4. Note that there is an error in Algorithm R as printed, see errata at [0]. [0] https://www-cs-faculty.stanford.edu/~knuth/all3-prepre.ps.gz Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: MAX_FROM_BITS() should be unsignedDavid Gibson2023-12-041-1/+1
| | | | | | | | | | | | | | | MAX_FROM_BITS() computes the maximum value representable in a number of bits. The expression for that is an unsigned value, but we explicitly cast it to a signed int. It looks like this is because one of the main users is for FD_REF_MAX, which is used to bound fd values, typically stored as a signed int. The value MAX_FROM_BITS() is calculating is naturally non-negative, though, so it makes more sense for it to be unsigned, and to move the case to the definition of FD_REF_MAX. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* port_fwd, util: Include additional headers to fix build with muslStefano Brivio2023-12-021-0/+1
| | | | | | | | | | | | | lseek() is declared in unistd.h, and stdio.h provides sscanf(). Include these two headers in port_fwd.c. SIGCHLD, even if used exclusively for clone(), is defined in signal.h: add the include to util.h, as NS_CALL needs it. Reported-by: lemmi <lemmi@nerd2nerd.org> Link: https://github.com/void-linux/void-packages/actions/runs/6999782606/job/19039526604#step:7:57 Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* port_fwd, util: Don't bind UDP ports with opposite-side bound TCP portsStefano Brivio2023-11-221-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When pasta periodically scans bound ports and binds them on the other side in order to forward traffic, we bind UDP ports for corresponding TCP port numbers, too, to support protocols and applications such as iperf3 which use UDP port numbers matching the ones used by the TCP data connection. If we scan UDP ports in order to bind UDP ports, we skip detection of the UDP ports we already bound ourselves, to avoid looping back our own ports. Same with scanning and binding TCP ports. But if we scan for TCP ports in order to bind UDP ports, we need to skip bound TCP ports too, otherwise, as David pointed out: - we find a bound TCP port on side A, and bind the corresponding TCP and UDP ports on side B - at the next periodic scan, we find that UDP port bound on side B, and we bind the corresponding UDP port on side A - at this point, we unbind that UDP port on side B: we would otherwise loop back our own port. To fix this, we need to avoid binding UDP ports that we already bound, on the other side, as a consequence of finding a corresponding bound TCP port. Reproducing this issue is straightforward: ./pasta -- iperf3 -s # Wait one second, then from another terminal: iperf3 -c ::1 -u Reported-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp> Analysed-by: David Gibson <david@gibson.dropbear.id.au> Fixes: 457ff122e33c ("udp,pasta: Periodically scan for ports to automatically forward") Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Add open_in_ns() helperDavid Gibson2023-11-071-0/+1
| | | | | | | | | | Most of our helpers which need to enter the pasta network namespace are quite specialised. Add one which is rather general - it just open()s a given file in the namespace context and returns the fd back to the main namespace. This will have some future uses. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* port_fwd: Move automatic port forwarding code to port_fwd.[ch]David Gibson2023-11-071-2/+0
| | | | | | | | | | | | | The implementation of scanning /proc files to do automatic port forwarding is a bit awkwardly split between procfs_scan_listen() in util.c, get_bound_ports() and related functions in conf.c and the initial setup code in conf(). Consolidate all of this into port_fwd.h, which already has some related definitions, and a new port_fwd.c. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* cppcheck: Make many pointers constDavid Gibson2023-10-041-2/+2
| | | | | | | | | Newer versions of cppcheck (as of 2.12.0, at least) added a warning for pointers which could be declared to point at const data, but aren't. Based on that, make many pointers throughout the codebase const. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Consolidate and improve workarounds for clang-tidy issue 58992David Gibson2023-09-271-0/+41
| | | | | | | | | | | | | | | | | | | | | We have several workarounds for a clang-tidy bug where the checker doesn't recognize that a number of system calls write to - and therefore initialise - a socket address. We can't neatly use a suppression, because the bogus warning shows up some time after the actual system call, when we access a field of the socket address which clang-tidy erroneously thinks is uninitialised. Consolidate these workarounds into one place by using macros to implement wrappers around affected system calls which add a memset() of the sockaddr to silence clang-tidy. This removes the need for the individual memset() workarounds at the callers - and the somewhat longwinded explanatory comments. We can then use a #define to not include the hack in "real" builds, but only consider it for clang-tidy. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Avoid shadowing index(3)David Gibson2023-09-271-1/+1
| | | | | | | | | | | | | | | | | A classic gotcha of the standard C library is that its unwise to call any variable 'index' because it will shadow the standard string library function index(3). This can cause warnings from cppcheck amongst others, and it also means that if the variable is removed you tend to get confusing type errors (or sometimes nothing at all) instead of a nice simple "name is not defined" error. Strictly speaking this only occurs if <string.h> is included, but that is so common that as a rule it's best to just avoid it always. We have a number of places which hit this trap, so rename variables and parameters to avoid it. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Fix licensing information display in --version2023_09_08.05627dcStefano Brivio2023-09-081-2/+2
| | | | | | | The regular expression I used when relicensing to GPLv2+ missed this. Fixes: ca2749e1bd52 ("passt: Relicense to GPL 2.0, or any later version") Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp, udp: Don't include destination address in partially precomputed csumsDavid Gibson2023-08-221-1/+3
| | | | | | | | | | | | | | | | | | | | | | We partially prepopulate IP and TCP header structures including, amongst other things the destination address, which for IPv4 is always the known address of the guest/namespace. We partially precompute both the IPv4 header checksum and the TCP checksum based on this. In future we're going to want more flexibility with controlling the destination for IPv4 (as we already do for IPv6), so this precomputed value gets in the way. Therefore remove the IPv4 destination from the precomputed checksum and fold it into the checksum update when we actually send a packet. Doing this means we no longer need to recompute those partial sums when the destination address changes ({tcp,udp}_update_l2_buf()) and instead the computation can be moved to compile time. This means while we perform slightly more computations on each packet, we slightly reduce the amount of memory we need to access. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Make ns_enter() a void function and report setns() errorsDavid Gibson2023-08-041-1/+1
| | | | | | | | | | | | | | | | ns_enter() returns an integer... but it's always zero. If we actually fail the function doesn't return. Therefore it makes more sense for this to be a function returning void, and we can remove the cases where we pointlessly checked its return value. In addition ns_enter() is usually called from an ephemeral thread created by NS_CALL(). That means that the exit(EXIT_FAILURE) there usually won't be reported (since NS_CALL() doesn't wait() for the thread). So, use die() instead to print out some information in the unlikely event that our setns() here does fail. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util, conf: Add and use ns_is_init() helperStefano Brivio2023-05-231-0/+2
| | | | | | | | | | We'll need this in isolate_initial(). While at it, don't rely on BUFSIZ: the earlier issue we had with musl reminded me it's not a magic "everything will fit" value. Size the read buffer to what we actually need from uid_map, and check for the final newline too, because uid_map is organised in lines. 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>
* util: Carry own definition of __bswap_constant{16,32}Stefano Brivio2023-03-091-0/+11
| | | | | | | | | | musl doesn't define those, use our own definition there. This is a trivial implementation, similar to what's shipped by e.g. uClibc, glibc, libiio. Reported-by: Chris Kuhn <kuhnchris+github@kuhnchris.eu> Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* Fix definitions of SOCKET_MAX, TCP_MAX_CONNSStefano Brivio2023-02-271-0/+2
| | | | | | | | ...and, given that I keep getting this wrong, add a convenience macro, MAX_FROM_BITS(). Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* Make assertions actually usefulDavid Gibson2023-02-121-1/+19
| | | | | | | | | | | | | | | | | | There are some places in passt/pasta which #include <assert.h> and make various assertions. If we hit these something has already gone wrong, but they're there so that we a useful message instead of cryptic misbehaviour if assumptions we thought were correct turn out not to be. Except.. the glibc implementation of assert() uses syscalls that aren't in our seccomp filter, so we'll get a SIGSYS before it actually prints the message. Work around this by adding our own ASSERT() implementation using our existing err() function to log the message, and an abort(). The abort() probably also won't work exactly right with seccomp, but once we've printed the message, dying with a SIGSYS works just as well as dying with a SIGABRT. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Use abstracted tap headerDavid Gibson2023-01-231-7/+0
| | | | | | | | | Update the UDP code to use the tap layer abstractions for initializing and updating the L2 and lower headers. This will make adding other tap backends in future easier. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Parameterize ethernet header initializer macroDavid Gibson2023-01-231-9/+2
| | | | | | | | | We have separate IPv4 and IPv6 versions of a macro to construct an initializer for ethernet headers. However, now that we have htons_constant it's easy to simply paramterize this with the ethernet protocol number. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Introduce hton*_constant() in place of #ifdefsDavid Gibson2023-01-231-26/+11
| | | | | | | | | | | We have several places where we have fairly ugly #ifdefs on __BYTE_ORDER where we need network order values in a constant expression (so we can't use htons() or htonl()). We can do this more cleanly by using a single __BYTE_ORDER ifdef to define htons_constant() and htonl_constant() macros, then using those in all the other places. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Pre-populate msg_names with local addressDavid Gibson2023-01-131-0/+7
| | | | | | | | | | | udp_splice_namebuf is now used only for spliced sending, and so it is only ever populated with the localhost address, either IPv4 or IPv6. So, replace the awkward initialization in udp_sock_handler_splice() with statically initialized versions for IPv4 and IPv6. We then just need to update the port number in udp_sock_handler_splice(). Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util, pasta: Add do_clone() wrapper around __clone2() and clone()Stefano Brivio2022-11-161-3/+5
| | | | | | | | | | | | | | | Spotted in Debian's buildd logs: on ia64, clone(2) is not available: the glibc wrapper is named __clone2() and it takes, additionally, the size of the stack area passed by the caller. Add a do_clone() wrapper handling the different cases, and also taking care of pointing the child's stack in the middle of the allocated area: on PA-RISC (hppa), handled by clone(), the stack grows up, and on ia64 the stack grows down, but the register backing store grows up -- and I think it might be actually used here. Suggested-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Use typing to reduce chances of IPv4 endianness errorsDavid Gibson2022-11-041-2/+10
| | | | | | | | | | | | | | | | | | | We recently corrected some errors handling the endianness of IPv4 addresses. These are very easy errors to make since although we mostly store them in network endianness, we sometimes need to manipulate them in host endianness. To reduce the chances of making such mistakes again, change to always using a (struct in_addr) instead of a bare in_addr_t or uint32_t to store network endian addresses. This makes it harder to accidentally do arithmetic or comparisons on such addresses as if they were host endian. We introduce a number of IN4_IS_ADDR_*() helpers to make it easier to directly work with struct in_addr values. This has the additional benefit of making the IPv4 and IPv6 paths more visually similar. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Set NS_FN_STACK_SIZE to one eighth of ulimit-reported maximum stack size2022_10_22.b68da10Stefano Brivio2022-10-221-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ...instead of one fourth. On the main() -> conf() -> nl_sock_init() call path, LTO from gcc 12 on (at least) x86_64 decides to inline... everything: nl_sock_init() is effectively part of main(), after commit 3e2eb4337bc0 ("conf: Bind inbound ports with CAP_NET_BIND_SERVICE before isolate_user()"). This means we exceed the maximum stack size, and we get SIGSEGV, under any condition, at start time, as reported by Andrea on a recent build for CentOS Stream 9. The calculation of NS_FN_STACK_SIZE, which is the stack size we reserve for clones, was previously obtained by dividing the maximum stack size by two, to avoid an explicit check on architecture (on PA-RISC, also known as hppa, the stack grows up, so we point the clone to the middle of this area), and then further divided by two to allow for any additional usage in the caller. Well, if there are essentially no function calls anymore, this is not enough. Divide it by eight, which is anyway much more than possibly needed by any clone()d callee. I think this is robust, so it's a fix in some sense. Strictly speaking, though, we have no formal guarantees that this isn't either too little or too much. What we should do, eventually: check cloned() callees, there are just thirteen of them at the moment. Note down any stack usage (they are mostly small helpers), bonus points for an automated way at build time, quadruple that or so, to allow for extreme clumsiness, and use as NS_FN_STACK_SIZE. Perhaps introduce a specific condition for hppa. Reported-by: Andrea Bolognani <abologna@redhat.com> Fixes: 3e2eb4337bc0 ("conf: Bind inbound ports with CAP_NET_BIND_SERVICE before isolate_user()") Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Replace FWRITE with a functionDavid Gibson2022-10-151-12/+1
| | | | | | | | | | | | | | In a few places we use the FWRITE() macro to open a file, replace it's contents with a given string and close it again. There's no real reason this needs to be a macro rather than just a function though. Turn it into a function 'write_file()' and make some ancillary cleanups while we're there: - Add a return code so the caller can handle giving a useful error message - Handle the case of short write()s (unlikely, but possible) - Add O_TRUNC, to make sure we replace the existing contents entirely Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util.h: Add missing gcc pragma push before pragma popStefano Brivio2022-10-151-0/+1
| | | | | | | | | While building with clang: ./util.h:176:24: warning: pragma diagnostic pop could not pop, no matching push [-Wunknown-pragmas] Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* Don't create 'tap' socket for ports that are bound to loopback onlyStefano Brivio2022-10-151-0/+3
| | | | | | | | | | | | | | | | | | | | | If the user specifies an explicit loopback address for a port binding, we're going to use that address for the 'tap' socket, and the same exact address for the 'spliced' socket (because those are, by definition, only bound to loopback addresses). This means that the second binding will fail, and, unexpectedly, the port is forwarded, but via tap device, which means the source address in the namespace won't be a loopback address. Make it explicit under which conditions we're creating which kind of socket, by refactoring tcp_sock_init() into two separate functions for IPv4 and IPv6 and gathering those conditions at the beginning. Also, don't create spliced sockets if the user specifies explicitly a non-loopback address, those are harmless but not desired either. Fixes: 3c6ae625101a ("conf, tcp, udp: Allow address specification for forwarded ports") Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* conf, tcp, udp: Allow specification of interface to bind toStefano Brivio2022-10-151-1/+2
| | | | | | | | | | | | | | | | Since kernel version 5.7, commit c427bfec18f2 ("net: core: enable SO_BINDTODEVICE for non-root users"), we can bind sockets to interfaces, if they haven't been bound yet (as in bind()). Introduce an optional interface specification for forwarded ports, prefixed by %, that can be passed together with an address. Reported use case: running local services that use ports we want to have externally forwarded: https://github.com/containers/podman/issues/14425 Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* conf, log, Makefile: Add versioning informationStefano Brivio2022-10-151-0/+8
| | | | | | | Add a --version option displaying that, and also include this information in the log files. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Move logging functions to a new file, log.cStefano Brivio2022-10-141-16/+0
| | | | | | | | Logging to file is going to add some further complexity that we don't want to squeeze into util.c. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* udp: Replace pragma to ignore bogus stringop-overread warning with workaroundStefano Brivio2022-09-291-23/+0
| | | | | | | | | | | | | | | | | | | Commit c318ffcb4c93 ("udp: Ignore bogus -Wstringop-overread for write() from gcc 12.1") uses a gcc pragma to ignore a bogus warning, which started appearing on gcc 12.1 (aarch64 and x86_64) due to: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103483 ...but gcc 12.2 has the same issue. Not just that: if LTO is enabled, the pragma itself is ignored (this wasn't the case with gcc 12.1), because of: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80922 Drop the pragma, and assign a frame (in the networking sense) pointer from the offset of the Ethernet header in the buffer, then pass it to write() and pcap(), so that gcc doesn't obsess anymore with the fact that an Ethernet header is 14 bytes and we're sending more than that. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* cppcheck: Use inline suppression for ffsl()David Gibson2022-09-291-0/+1
| | | | | | | | | | We define our own ffsl() as a weak symbol, in case our C library doesn't include it. On glibc systems which *do* include it, this causes a cppcheck warning because unsurprisingly our version doesn't pick the same argument names. Convert the suppression for this into an inline suppression. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Move self-isolation code into a separate fileDavid Gibson2022-09-131-2/+0
| | | | | | | | passt/pasta contains a number of routines designed to isolate passt from the rest of the system for security. These are spread through util.c and passt.c. Move them together into a new isolation.c file. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Consolidate determination of UID/GID to run asDavid Gibson2022-09-131-1/+0
| | | | | | | | | | | | Currently the logic to work out what UID and GID we will run as is spread across conf(). If --runas is specified it's handled in conf_runas(), otherwise it's handled by check_root(), which depends on initialization of the uid and gid variables by either conf() itself or conf_runas(). Make this clearer by putting all the UID and GID logic into a single conf_ugid() function. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Split checking for root from dropping root privilegeDavid Gibson2022-09-131-0/+1
| | | | | | | | | | | | | | | | | | check_root() both checks to see if we are root (in the init namespace), and if we are drops to an unprivileged user. To make future cleanups simpler, split the checking for root (now in check_root()) from the actual dropping of privilege (now in drop_root()). Note that this does slightly alter semantics. Previously we would only setuid() if we were originally root (in the init namespace). Now we will always setuid() and setgid(), though it won't actually change anything if we weren't privileged to begin with. This also means that we will now always attempt to switch to the user specified with --runas, even if we aren't (init namespace) root to begin with. Obviously this will fail with an error if we weren't privileged to start with. --help and the man page are updated accordingly. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Don't store UID & GID persistently in the context structureDavid Gibson2022-09-131-1/+1
| | | | | | | | c->uid and c->gid are first set in conf(), and last used in check_root() itself called from conf(). Therefore these don't need to be fields in the long lived context structure and can instead be locals in conf(). Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Clarify semantics of c->v4 and c->v6 variablesDavid Gibson2022-07-301-6/+0
| | | | | | | | | | | | | | | | | | | | | The v4 and v6 fields of the context structure can be confusing, because they change meaning part way through the code: Before conf_ip(), they are booleans which indicate whether the -4 or -6 options have been given. After conf_ip() they are DISABLED|ENABLED|PROBE enums which indicate whether the IP version is available (which means both that it was allowed on the command line and we were able to configure it). The PROBE variant of the enum is only used locally within conf_ip() and since recent changes there it no longer has a real purpose different from ENABLED. Simplify this all by making the context fields always just a boolean indicating the availability of the IP version. They both default to 1, but can be set to 0 by either command line options or configuration failures. We use some local variables in conf() for tracking the state of the command line options on their own. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> [sbrivio: Minor coding style fix in conf.c] Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* conf: Add --runas option, changing to given UID and GID if started as rootStefano Brivio2022-05-191-0/+1
| | | | | | | | | | | | | | On some systems, user and group "nobody" might not be available. The new --runas option allows to override the default "nobody" choice if started as root. Now that we allow this, drop the initgroups() call that was used to add any additional groups for the given user, as that might now grant unnecessarily broad permissions. For instance, several distributions have a "kvm" group to allow regular user access to /dev/kvm, and we don't need that in passt or pasta. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Ignore bogus -Wstringop-overread for write() from gcc 12.1Stefano Brivio2022-05-191-0/+23
| | | | | | | | | | | | | | | | | With current OpenSUSE Tumbleweed on aarch64 (gcc-12-1.3.aarch64) and on x86_64 (gcc-12-1.4.x86_64), but curiously not on armv7hl (gcc-12-1.3.armv7hl), gcc warns about using the _pointer_ to the 802.3 header to write the whole frame to the tap descriptor: reading between 62 and 4294967357 bytes from a region of size 14 which is bogus: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103483 Probably declaring udp_sock_fill_data_v{4,6}() as noinline would "fix" this, but that's on the data path, so I'd rather not. Use a gcc pragma instead. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* conf, tcp, udp: Allow address specification for forwarded portsStefano Brivio2022-05-011-9/+2
| | | | | | | | | | | | | This feature is available in slirp4netns but was missing in passt and pasta. Given that we don't do dynamic memory allocation, we need to bind sockets while parsing port configuration. This means we need to process all other options first, as they might affect addressing and IP version support. It also implies a minor rework of how TCP and UDP implementations bind sockets. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Argument cannot be negative, CWE-687Stefano Brivio2022-04-071-0/+12
| | | | | | Actually harmless. Reported by Coverity. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Mark constant references as constStefano Brivio2022-03-291-4/+4
| | | | Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Add include guardsStefano Brivio2022-03-291-0/+5
| | | | | | | ...at the moment, just for consistency with packet.h, icmp.h, tcp.h and udp.h. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Packet abstraction with mandatory boundary checksStefano Brivio2022-03-291-1/+4
| | | | | | | | | | | | | | | | | | | | Implement a packet abstraction providing boundary and size checks based on packet descriptors: packets stored in a buffer can be queued into a pool (without storage of its own), and data can be retrieved referring to an index in the pool, specifying offset and length. Checks ensure data is not read outside the boundaries of buffer and descriptors, and that packets added to a pool are within the buffer range with valid offset and indices. This implies a wider rework: usage of the "queueing" part of the abstraction mostly affects tap_handler_{passt,pasta}() functions and their callees, while the "fetching" part affects all the guest or tap facing implementations: TCP, UDP, ICMP, ARP, NDP, DHCP and DHCPv6 handlers. Suggested-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Refactor to use events instead of states, split out spliced implementationStefano Brivio2022-03-281-1/+3
| | | | | | | | | | | | | | | | | | | | | Using events and flags instead of states makes the implementation much more straightforward: actions are mostly centered on events that occurred on the connection rather than states. An example is given by the ESTABLISHED_SOCK_FIN_SENT and FIN_WAIT_1_SOCK_FIN abominations: we don't actually care about which side started closing the connection to handle closing of connection halves. Split out the spliced implementation, as it has very little in common with the "regular" TCP path. Refactor things here and there to improve clarity. Add helpers to trace where resets and flag settings come from. No functional changes intended. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Use standard int typesStefano Brivio2022-03-251-6/+6
| | | | | | ...instead of kernel-like short notations. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Drop CHECK_SET_MIN_MAX{,_PROTO_FD} macrosStefano Brivio2022-03-251-14/+0
| | | | | | | ...those were used when epoll references used to be socket numbers, they should have gone away a long time ago. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* conf, util, tap: Implement --trace option for extra verbose loggingStefano Brivio2022-03-251-0/+8
| | | | | | | | --debug can be a bit too noisy, especially as single packets or socket messages are logged: implement a new option, --trace, implying --debug, that enables all debug messages. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt, pasta: Namespace-based sandboxing, defer seccomp policy applicationStefano Brivio2022-02-211-1/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To reach (at least) a conceptually equivalent security level as implemented by --enable-sandbox in slirp4netns, we need to create a new mount namespace and pivot_root() into a new (empty) mountpoint, so that passt and pasta can't access any filesystem resource after initialisation. While at it, also detach IPC, PID (only for passt, to prevent vulnerabilities based on the knowledge of a target PID), and UTS namespaces. With this approach, if we apply the seccomp filters right after the configuration step, the number of allowed syscalls grows further. To prevent this, defer the application of seccomp policies after the initialisation phase, before the main loop, that's where we expect bad things to happen, potentially. This way, we get back to 22 allowed syscalls for passt and 34 for pasta, on x86_64. While at it, move #syscalls notes to specific code paths wherever it conceptually makes sense. We have to open all the file handles we'll ever need before sandboxing: - the packet capture file can only be opened once, drop instance numbers from the default path and use the (pre-sandbox) PID instead - /proc/net/tcp{,v6} and /proc/net/udp{,v6}, for automatic detection of bound ports in pasta mode, are now opened only once, before sandboxing, and their handles are stored in the execution context - the UNIX domain socket for passt is also bound only once, before sandboxing: to reject clients after the first one, instead of closing the listening socket, keep it open, accept and immediately discard new connection if we already have a valid one Clarify the (unchanged) behaviour for --netns-only in the man page. To actually make passt and pasta processes run in a separate PID namespace, we need to unshare(CLONE_NEWPID) before forking to background (if configured to do so). Introduce a small daemon() implementation, __daemon(), that additionally saves the PID file before forking. While running in foreground, the process itself can't move to a new PID namespace (a process can't change the notion of its own PID): mention that in the man page. For some reason, fork() in a detached PID namespace causes SIGTERM and SIGQUIT to be ignored, even if the handler is still reported as SIG_DFL: add a signal handler that just exits. We can now drop most of the pasta_child_handler() implementation, that took care of terminating all processes running in the same namespace, if pasta started a shell: the shell itself is now the init process in that namespace, and all children will terminate once the init process exits. Issuing 'echo $$' in a detached PID namespace won't return the actual namespace PID as seen from the init namespace: adapt demo and test setup scripts to reflect that. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-16 18:36:19 +0000