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* epoll: Always use epoll_ref for the epoll data variableDavid Gibson2023-08-131-5/+6
| | | | | | | | | | | | | | | | | | | | | | epoll_ref contains a variety of information useful when handling epoll events on our sockets, and we place it in the epoll_event data field returned by epoll. However, for a few other things we use the 'fd' field in the standard union of types for that data field. This actually introduces a bug which is vanishingly unlikely to hit in practice, but very nasty if it ever did: theoretically if we had a very large file descriptor number for fd_tap or fd_tap_listen it could overflow into bits that overlap with the 'proto' field in epoll_ref. With some very bad luck this could mean that we mistakenly think an event on a regular socket is an event on fd_tap or fd_tap_listen. More practically, using different (but overlapping) fields of the epoll_data means we can't unify dispatch for the various different objects in the epoll. Therefore use the same epoll_ref as the data for the tap fds and the netns quit fd, adding new fd type values to describe them. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* epoll: Generalize epoll_ref to cover things other than socketsDavid Gibson2023-08-131-13/+12
| | | | | | | | | | | | | | The epoll_ref type includes fields for the IP protocol of a socket, and the socket fd. However, we already have a few things in the epoll which aren't protocol sockets, and we may have more in future. Rename these fields to an abstract "fd type" and file descriptor for more generality. Similarly, rather than using existing IP protocol numbers for the type, introduce our own number space. For now these just correspond to the supported protocols, but we'll expand on that in future. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Use C11 anonymous members to make poll refs less verbose to useDavid Gibson2023-08-041-4/+4
| | | | | | | | | | | | union epoll_ref has a deeply nested set of structs and unions to let us subdivide it into the various different fields we want. This means that referencing elements can involve an awkward long string of intermediate fields. Using C11 anonymous structs and unions lets us do this less clumsily. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Fix error check for signal(), improve error messagesStefano Brivio2023-04-131-2/+9
| | | | | | | | | | | | | | Valtteri reports that if SIGPIPE already has a disposition set by the parent process, such as systemd with the default setting of IgnoreSIGPIPE=yes, signal() will return the previous value, not zero, and this is not an error: check for SIG_ERR instead. While at it, split messages for failures of sigaction() and signal(), and report the actual error. Reported-by: Valtteri Vuorikoski <vuori@notcom.org> Fixes: 8534be076c73 ("Catch failures when installing signal handlers") 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: Fix header includes to build with muslChris Kuhn2023-03-091-0/+2
| | | | | | | | | | | | | | | Roughly inspired from a patch by Chris Kuhn: fix up includes so that we can build against musl: glibc is more lenient as headers generally include a larger amount of other headers. Compared to the original patch, I only included what was needed directly in C files, instead of adding blanket includes in local header files. It's a bit more involved, but more consistent with the current (not ideal) situation. 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>
* conf, passt: Rename stderr to force_stderrChris Kuhn2023-03-091-1/+1
| | | | | | | | | | | | While building against musl, gcc informs us that 'stderr' is a protected keyword. This probably comes from a #define stderr (stderr) in musl's stdio.h, to avoid a clash with extern FILE *const stderr, but I didn't really track it down. Just rename it to force_stderr, it makes more sense. [sbrivio: Added commit message] Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* convert all remaining err() followed by exit() to die()Laine Stump2023-02-161-8/+4
| | | | | | | | This actually leaves us with 0 uses of err(), but someone could want to use it in the future, so we may as well leave it around. Signed-off-by: Laine Stump <laine@redhat.com> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* log to stderr until process is daemonized, even if a log file is setLaine Stump2023-02-161-7/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | Once a log file (specified on the commandline) is opened, the logging functions will stop sending error logs to stderr, which is annoying if passt has been started by another process that wants to collect error messages from stderr so it can report why passt failed to start. It would be much nicer if passt continued sending all log messages to stderr until it daemonizes itself (at which point the process that started passt can assume that it was started successfully). The system log mask is set to LOG_EMERG when the process starts, and we're already using that to do "special" logging during the period from process start until the log level requested on the commandline is processed (setting the log mask to something else). This period *almost* matches with "the time before the process is daemonized"; if we just delay setting the log mask a tiny bit, then it will match exactly, and we can use it to determine if we need to send log messages to stderr even when a log file has been specified and opened. This patch delays the setting of the log mask until immediately before the call to __daemon(). It also modifies logfn() slightly, so that it will log to stderr any time log mask is LOG_EMERG, even if a log file has been opened. Signed-off-by: Laine Stump <laine@redhat.com> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* pasta: Wait for tap to be set up before spawning commandStefano Brivio2023-02-121-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Adapted from a patch by Paul Holzinger: when pasta spawns a command, operating without a pre-existing user and network namespace, it needs to wait for the tap device to be configured and its handler ready, before the command is actually executed. Otherwise, something like: pasta --config-net nslookup passt.top usually fails as the nslookup command is issued before the network interface is ready. We can't adopt a simpler approach based on SIGSTOP and SIGCONT here: the child runs in a separate PID namespace, so it can't send SIGSTOP to itself as the kernel sees the child as init process and blocks the delivery of the signal. We could send SIGSTOP from the parent, but this wouldn't avoid the possible condition where the child isn't ready to wait for it when the parent sends it, also raised by Paul -- and SIGSTOP can't be blocked, so it can never be pending. Use SIGUSR1 instead: mask it before clone(), so that the child starts with it blocked, and can safely wait for it. Once the parent is ready, it sends SIGUSR1 to the child. If SIGUSR1 is sent before the child is waiting for it, the kernel will queue it for us, because it's blocked. Reported-by: Paul Holzinger <pholzing@redhat.com> Fixes: 1392bc5ca002 ("Allow pasta to take a command to execute") Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt, tap: Add --fd optionRichard W.M. Jones2022-11-251-1/+0
| | | | | | | | | This passes a fully connected stream socket to passt. Signed-off-by: Richard W.M. Jones <rjones@redhat.com> [sbrivio: reuse fd_tap instead of adding a new descriptor, imply --one-off on --fd, add to optstring and usage()] Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Move __setlogmask() calls before output unrelated to configurationStefano Brivio2022-11-101-8/+8
| | | | | | | | | | | ...so that we avoid printing some lines twice because log-level is still set to LOG_EMERG, as if logging configuration didn't happen yet. While at it, note that logging to stderr doesn't really depend on whether debug mode is enabled or not. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Use typing to reduce chances of IPv4 endianness errorsDavid Gibson2022-11-041-1/+1
| | | | | | | | | | | | | | | | | | | 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>
* icmp: Don't discard first reply sequence for a given echo ID2022_10_26.f212044Stefano Brivio2022-10-271-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | In pasta mode, ICMP and ICMPv6 echo sockets relay back to us any reply we send: we're on the same host as the target, after all. We discard them by comparing the last sequence we sent with the sequence we receive. However, on the first reply for a given identifier, the sequence might be zero, depending on the implementation of ping(8): we need another value to indicate we haven't sent any sequence number, yet. Use -1 as initialiser in the echo identifier map. This is visible with Busybox's ping, and was reported by Paul on the integration at https://github.com/containers/podman/pull/16141, with: $ podman run --net=pasta alpine ping -c 2 192.168.188.1 ...where only the second reply would be routed back. Reported-by: Paul Holzinger <pholzing@redhat.com> Fixes: 33482d5bf293 ("passt: Add PASTA mode, major rework") Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* isolation: Clarify various self-isolation stepsDavid Gibson2022-10-151-5/+3
| | | | | | | | | | We have a number of steps of self-isolation scattered across our code. Improve function names and add comments to make it clearer what the self isolation model is, what the steps do, and why they happen at the points they happen. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* log, conf: Add support for logging to fileStefano Brivio2022-10-141-0/+1
| | | | | | | | | | | | | | | | | | | | | | In some environments, such as KubeVirt pods, we might not have a system logger available. We could choose to run in foreground, but this takes away the convenient synchronisation mechanism derived from forking to background when interfaces are ready. Add optional logging to file with -l/--log-file and --log-size. Unfortunately, this means we need to duplicate features that are more appropriately implemented by a system logger, such as rotation. Keep that reasonably simple, by using fallocate() with range collapsing where supported (Linux kernel >= 3.15, extent-based ext4 and XFS) and falling back to an unsophisticated block-by-block moving of entries toward the beginning of the file once we reach the (mandatory) size limit. While at it, clarify the role of LOG_EMERG in passt.c. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* Move logging functions to a new file, log.cStefano Brivio2022-10-141-0/+1
| | | | | | | | 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>
* cppcheck: Suppress same-value-in-ternary branches warningDavid Gibson2022-09-291-0/+1
| | | | | | | | | | | | | | TIMER_INTERVAL is the minimum of two separately defined intervals which happen to have the same value at present. This results in an expression which has the same value in both branches of a ternary operator, which cppcheck warngs about. This is logically sound in this case, so suppress the error (we appear to already have a similar suppression for clang-tidy). Also add an unmatchedSuppression suppression, since only some cppcheck versions complain about this instance. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Catch failures when installing signal handlersDavid Gibson2022-09-291-2/+4
| | | | | | | | | Stop ignoring the return codes from sigaction() and signal(). Unlikely to happen in practice, but if it ever did it could lead to really hard to debug problems. So, take clang-tidy's advice and check for errors here. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Handle userns isolation and dropping root at the same timeDavid Gibson2022-09-131-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | passt/pasta can interact with user namespaces in a number of ways: 1) With --netns-only we'll remain in our original user namespace 2) With --userns or a PID option to pasta we'll join either the given user namespace or that of the PID 3) When pasta spawns a shell or command we'll start a new user namespace for the command and then join it 4) With passt we'll create a new user namespace when we sandbox() ourself However (3) and (4) turn out to have essentially the same effect. In both cases we create one new user namespace. The spawned command starts there, and passt/pasta itself will live there from sandbox() onwards. Because of this, we can simplify user namespace handling by moving the userns handling earlier, to the same point we drop root in the original namespace. Extend the drop_user() function to isolate_user() which does both. After switching UID and GID in the original userns, isolate_user() will either join or create the userns we require. When we spawn a command with pasta_start_ns()/pasta_setup_ns() we no longer need to create a userns, because we're already made one. sandbox() likewise no longer needs to create (or join) an userns because we're already in the one we need. We no longer need c->pasta_userns_fd, since the fd is only used locally in isolate_user(). Likewise we can replace c->netns_only with a local in conf(), since it's not used outside there. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Move self-isolation code into a separate fileDavid Gibson2022-09-131-112/+1
| | | | | | | | 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>
* Don't unnecessarily avoid CLOEXEC flags2022_08_24.60ffc5bDavid Gibson2022-08-241-4/+2
| | | | | | | | | | | | | | | | There are several places in the passt code where we have lint overrides because we're not adding CLOEXEC flags to open or other operations. Comments suggest this is because it's before we fork() into the background but we'll need those file descriptors after we're in the background. However, as the name suggests CLOEXEC closes on exec(), not on fork(). The only place we exec() is either super early invoke the avx2 version of the binary, or when we start a shell in pasta mode, which certainly *doesn't* require the fds in question. Add the CLOEXEC flag in those places, and remove the lint overrides. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Make substructures for IPv4 and IPv6 specific context informationDavid Gibson2022-07-301-1/+1
| | | | | | | | | | | | The context structure contains a batch of fields specific to IPv4 and to IPv6 connectivity. Split those out into a sub-structure. This allows the conf_ip4() and conf_ip6() functions, which take the entire context but touch very little of it, to be given more specific parameters, making it clearer what it affects without stepping through the code. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Separate IPv4 and IPv6 configurationDavid Gibson2022-07-301-2/+2
| | | | | | | | | | | | | | | | | | | After recent changes, conf_ip() now has essentially entirely disjoint paths for IPv4 and IPv6 configuration. So, it's cleaner to split them out into different functions conf_ip4() and conf_ip6(). Splitting these out also lets us make the interface a bit nicer, having them return success or failure directly, rather than manipulating c->v4 and c->v6 to indicate success/failure of the two versions. Since these functions may also initialize the interface index for each protocol, it turns out we can then drop c->v4 and c->v6 entirely, replacing tests on those with tests on whether c->ifi4 or c->ifi6 is non-zero (since a 0 interface index is never valid). Signed-off-by: David Gibson <david@gibson.dropbear.id.au> [sbrivio: Whitespace fixes] Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Truncate PID file on open()Stefano Brivio2022-07-221-1/+1
| | | | | | | Otherwise, if the current PID has fewer digits than a previously written one, the content will be wrong. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Allow exit_group() system call in seccomp profilesStefano Brivio2022-07-141-0/+2
| | | | | | | | | | | | We handle SIGQUIT and SIGTERM calling exit(), which is usually implemented with the exit_group() system call. If we don't allow exit_group(), we'll get a SIGSYS while handling SIGQUIT and SIGTERM, which means a misleading non-zero exit code. Reported-by: Wenli Quan <wquan@redhat.com> Link: https://bugzilla.redhat.com/show_bug.cgi?id=2101990 Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* arch, passt: Use executable link to form AVX2 binary pathStefano Brivio2022-07-141-3/+6
| | | | | | | | | | | | | | | | ...instead of argv[0], which might or might not contain a valid path to the executable itself. Instead of mangling argv[0], use the same link to find out if we're already running the AVX2 build where supported. Alternatively, we could use execvpe(), but that might result in running a different installed version, in case e.g. the set of binaries is present in both /usr/bin and /usr/local/bin, with both being in $PATH. Reported-by: Wenli Quan <wquan@redhat.com> Link: https://bugzilla.redhat.com/show_bug.cgi?id=2101310 Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* conf: Add --runas option, changing to given UID and GID if started as rootStefano Brivio2022-05-191-46/+0
| | | | | | | | | | | | | | 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>
* conf, tcp, udp: Allow address specification for forwarded portsStefano Brivio2022-05-011-11/+11
| | | | | | | | | | | | | 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>
* passt: Improper use of negative value (CWE-394)Stefano Brivio2022-04-071-5/+14
| | | | | | Reported by Coverity. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Ignoring number of bytes read, CWE-252Stefano Brivio2022-04-051-2/+3
| | | | | | Harmless, assuming sane kernel behaviour. Reported by Coverity. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Accurate error reporting for sandbox()Stefano Brivio2022-03-291-10/+26
| | | | | | | It's actually quite easy to make it fail depending on the environment, accurately report errors here. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Fix android-cloexec-* clang-tidy warnings, re-enable checksStefano Brivio2022-03-291-4/+5
| | | | Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Mark constant references as constStefano Brivio2022-03-291-7/+7
| | | | Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp_splice: Close sockets right away on high number of open filesStefano Brivio2022-03-291-1/+1
| | | | | | | | | | | | | We can't take for granted that the hard limit for open files is big enough as to allow to delay closing sockets to a timer. Store the value of RTLIMIT_NOFILE we set at start, and use it to understand if we're approaching the limit with pending, spliced TCP connections. If that's the case, close sockets right away as soon as they're not needed, instead of deferring this task to a timer. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Rework timers to use timerfd instead of periodic bitmap scanStefano Brivio2022-03-291-4/+8
| | | | | | | | | | | | | | | | | | With a lot of concurrent connections, the bitmap scan approach is not really sustainable. Switch to per-connection timerfd timers, set based on events and on two new flags, ACK_FROM_TAP_DUE and ACK_TO_TAP_DUE. Timers are added to the common epoll list, and implement the existing timeouts. While at it, drop the CONN_ prefix from flag names, otherwise they get quite long, and fix the logic to decide if a connection has a local, possibly unreachable endpoint: we shouldn't go through the rest of tcp_conn_from_tap() if we reset the connection due to a successful bind(2), and we'll get EACCES if the port number is low. 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 Brivio2022-03-281-2/+2
| | | | | | | | | | | | | | | | | | | | | 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>
* conf, util, tap: Implement --trace option for extra verbose loggingStefano Brivio2022-03-251-1/+2
| | | | | | | | --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: Run-time selection of AVX2 buildStefano Brivio2022-02-281-0/+3
| | | | | | | | | | | | | Build-time selection of AVX2 flags and routines is not practical for distributions, but limiting AVX2 usage to checksum routines with specific run-time detection doesn't allow for easy performance gains from auto-vectorisation of batched packet handling routines. For x86_64, build non-AVX2 and AVX2 binaries, and implement a simple wrapper replacing the current executable with the AVX2 build if it's available, and if AVX2 is supported by the current CPU. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* seccomp: Adjust list of allowed syscalls for armv6l, armv7lStefano Brivio2022-02-261-3/+5
| | | | | | | | | | | It looks like glibc commonly implements clock_gettime(2) with clock_gettime64(), and uses recv() instead of recvfrom(), send() instead of sendto(), and sigreturn() instead of rt_sigreturn() on armv6l and armv7l. Adjust the list of system calls for armv6l and armv7l accordingly. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Don't warn on failed madvise()Stefano Brivio2022-02-261-2/+1
| | | | | | | | A kernel might not be configured with CONFIG_TRANSPARENT_HUGEPAGE, especially on embedded systems. Ignore the error, it doesn't affect functionality. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Explicitly check return value of chdir()Stefano Brivio2022-02-251-1/+3
| | | | | | | | ...it doesn't actually matter as we're checking errno at the very end, but, depending on build flags, chdir() might be declared with warn_unused_result and the compiler issues a warning. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Drop PASST_LEGACY_NO_OPTIONS sectionsStefano Brivio2022-02-221-2/+0
| | | | | | ...nobody uses those builds anymore. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* pasta: By default, quit if filesystem-bound net namespace goes awayStefano Brivio2022-02-211-1/+6
| | | | | | | | | | | | This should be convenient for users managing filesystem-bound network namespaces: monitor the base directory of the namespace and exit if the namespace given as PATH or NAME target is deleted. We can't add an inotify watch directly on the namespace directory, that won't work with nsfs. Add an option to disable this behaviour, --no-netns-quit. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Makefile, conf, passt: Drop passt4netns references, explicit argc checkStefano Brivio2022-02-211-2/+7
| | | | | | | | | | | Nobody currently calls this as passt4netns, that was the name I used before 'pasta', drop any reference before it's too late. While at it, explicitly check that argc is bigger than or equal to one, just as a defensive measure: argv[0] being NULL is not an issue anyway. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Make process not dumpable after sandboxingStefano Brivio2022-02-211-0/+2
| | | | | | | | | | | | | Two effects: - ptrace() on passt and pasta can only be done by root, so that even if somebody gains access to the same user, they won't be able to check data passed in syscalls anyway. No core dumps allowed either - /proc/PID files are owned by root:root, and they can't be read by the same user as the one passt or pasta are running with Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt, pasta: Namespace-based sandboxing, defer seccomp policy applicationStefano Brivio2022-02-211-47/+79
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* passt, tap: Daemonise once socket is ready without waiting for connectionStefano Brivio2022-01-281-2/+4
| | | | | | | | | | | | | The existing behaviour is not really practical: an automated agent in charge of starting both qemu and passt would need to fork itself to start passt, because passt won't fork to background until qemu connects, and the agent needs to unblock to start qemu. Instead of waiting for a connection to daemonise, do it right away as soon as a socket is available: that can be considered an initialised state already. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* seccomp: Add a number of alternate and per-arch syscallsStefano Brivio2022-01-261-5/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Depending on the C library, but not necessarily in all the functions we use, statx() might be used instead of stat(), getdents() instead of getdents64(), readlinkat() instead of readlink(), openat() instead of open(). On aarch64, it's clone() and not fork(), and dup3() instead of dup2() -- just allow the existing alternative instead of dealing with per-arch selections. Since glibc commit 9a7565403758 ("posix: Consolidate fork implementation"), we need to allow set_robust_list() for fork()/clone(), even in a single-threaded context. On some architectures, epoll_pwait() is provided instead of epoll_wait(), but never both. Same with newfstat() and fstat(), sigreturn() and rt_sigreturn(), getdents64() and getdents(), readlink() and readlinkat(), unlink() and unlinkat(), whereas pipe() might not be available, but pipe2() always is, exclusively or not. Seen on Fedora 34: newfstatat() is used on top of fstat(). syslog() is an actual system call on some glibc/arch combinations, instead of a connect()/send() implementation. On ppc64 and ppc64le, _llseek(), recv(), send() and getuid() are used. For ppc64 only: ugetrlimit() for the getrlimit() implementation, plus sigreturn() and fcntl64(). On s390x, additionally, we need to allow socketcall() (on top of socket()), and sigreturn() also for passt (not just for pasta). Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Makefile, seccomp: Fix build for i386, ppc64, ppc64leStefano Brivio2022-01-261-1/+1
| | | | | | | | | | | | | | | | | On some distributions, on ppc64, ulimit -s returns 'unlimited': add a reasonable default, and also make sure ulimit is invoked using the default shell, which should ensure ulimit is actually implemented. Also note that AUDIT_ARCH doesn't follow closely the naming reported by 'uname -m': convert for i386 and ppc as needed. While at it, move inclusion of seccomp.h after util.h, the former is less generic (cosmetic/clang-tidy only). Older kernel headers might lack a definition for AUDIT_ARCH_PPC64LE: define that explicitly if it's not available. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
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