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* udp: Rename UDP listening socketsDavid Gibson2024-07-191-1/+1
| | | | | | | | | | EPOLL_TYPE_UDP is now only used for "listening" sockets; long lived sockets which can initiate new flows. Rename to EPOLL_TYPE_UDP_LISTEN and associated functions to match. Along with that, remove the .orig field from union udp_listen_epoll_ref, since it is now always true. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Handle "spliced" datagrams with per-flow socketsDavid Gibson2024-07-191-0/+1
| | | | | | | | | | | | | | | | | | | | | When forwarding a datagram to a socket, we need to find a socket with a suitable local address to send it. Currently we keep track of such sockets in an array indexed by local port, but this can't properly handle cases where we have multiple local addresses in active use. For "spliced" (socket to socket) cases, improve this by instead opening a socket specifically for the target side of the flow. We connect() as well as bind()ing that socket, so that it will only receive the flow's reply packets, not anything else. We direct datagrams sent via that socket using the addresses from the flow table, effectively replacing bespoke addressing logic with the unified logic in fwd.c When we create the flow, we also take a duplicate of the originating socket, and use that to deliver reply datagrams back to the origin, again using addresses from the flow table entry. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* flow: Helper to create sockets based on flowsideDavid Gibson2024-07-191-3/+3
| | | | | | | | | We have upcoming use cases where it's useful to create new bound socket based on information from the flow table. Add flowside_sock_l4() to do this for either PIF_HOST or PIF_SPLICE sockets. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Handle errors on UDP socketsDavid Gibson2024-07-171-0/+29
| | | | | | | | | | | | | | | | | | Currently we ignore all events other than EPOLLIN on UDP sockets. This means that if we ever receive an EPOLLERR event, we'll enter an infinite loop on epoll, because we'll never do anything to clear the error. Luckily that doesn't seem to have happened in practice, but it's certainly fragile. Furthermore changes in how we handle UDP sockets with the flow table mean we will start receiving error events. Add handling of EPOLLERR events. For now we just read the error from the error queue (thereby clearing the error state) and print a debug message. We can add more substantial handling of specific events in future if we want to. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Add AF_UNSPEC support to sockaddr_ntop()David Gibson2024-07-171-0/+4
| | | | | | | | | | | Allow sockaddr_ntop() to format AF_UNSPEC socket addresses. There do exist a few cases where we might legitimately have either an AF_UNSPEC or a real address, such as the origin address from MSG_ERRQUEUE. Even in cases where we shouldn't get an AF_UNSPEC address, formatting it is likely to make things easier to debug if we ever somehow do. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: sock_l4() determine protocol from epoll type rather than the reverseDavid Gibson2024-07-051-22/+26
| | | | | | | | | | | | sock_l4() creates a socket of the given IP protocol number, and adds it to the epoll state. Currently it determines the correct tag for the epoll data based on the protocol. However, we have some future cases where we might want different semantics, and therefore epoll types, for sockets of the same protocol. So, change sock_l4() to take the epoll type as an explicit parameter, and determine the protocol from that. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Replace strerror() callsStefano Brivio2024-06-211-7/+5
| | | | | | | | | | | | | | Now that we have logging functions embedding perror() functionality, we can make _some_ calls more terse by using them. In many places, the strerror() calls are still more convenient because, for example, they are used in flow debugging functions, or because the return code variable of interest is not 'errno'. While at it, convert a few error messages from a scant perror style to proper failure descriptions. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* util: Split construction of bind socket address from the rest of sock_l4()David Gibson2024-06-141-53/+70
| | | | | | | | | | | | | sock_l4() creates, binds and otherwise prepares a new socket. It builds the socket address to bind from separately provided address and port. However, we have use cases coming up where it's more natural to construct the socket address in the caller. Prepare for this by adding sock_l4_sa() which takes a pre-constructed socket address, and rewriting sock_l4() in terms of it. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Use 'long' to represent millisecond durationsDavid Gibson2024-06-071-1/+1
| | | | | | | | | | timespec_diff_ms() returns an int representing a duration in milliseconds. This will overflow in about 25 days when an int is 32 bits. The way we use this function, we're probably not going to get a result that long, but it's not outrageously implausible. Use a long for safety. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Use unsigned indices for bits in bitmapsDavid Gibson2024-06-071-4/+4
| | | | | | | | | A negative bit index in a bitmap doesn't make sense. Avoid this by construction by using unsigned indices. While we're there adjust bitmap_isset() to return a bool instead of an int. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt, util: Move opening of PID file to its own functionStefano Brivio2024-05-231-0/+22
| | | | | | | We won't call it from main() any longer: move it. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
* util: Rename write_pidfile() to pidfile_write()Stefano Brivio2024-05-231-3/+3
| | | | | | | | As I'm adding pidfile_open() in the next patch. The function comment didn't match, by the way. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
* util, tcp: Add helper to display socket addressesDavid Gibson2024-05-221-0/+56
| | | | | | | | | | | When reporting errors, we sometimes want to show a relevant socket address. Doing so by extracting the various relevant fields can be pretty awkward, so introduce a sockaddr_ntop() helper to make it simpler. For now we just have one user in tcp.c, but I have further upcoming patches which can make use of it. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: fix confusion between offset in the iovec array and in the entry2024_03_20.71dd405Laurent Vivier2024-03-201-4/+5
| | | | | | | | | | | | | | | | | | | | In write_remainder() 'skip' is the offset to start the operation from in the iovec array. In iov_skip_bytes(), 'skip' is also the offset in the iovec array but 'offset' is the first unskipped byte in the iovec entry. As write_remainder() uses 'skip' for both, 'skip' is reset to the first unskipped byte in the iovec entry rather to staying the first unskipped byte in the iovec array. Fix the problem by introducing a new variable not to overwrite 'skip' on each loop. Fixes: 8bdb0883b441 ("util: Add write_remainder() helper") Signed-off-by: Laurent Vivier <lvivier@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* icmp: Use 'flowside' epoll references for ping socketsDavid Gibson2024-03-121-3/+1
| | | | | | | | | | | | | | | | Currently ping sockets use a custom epoll reference type which includes the ICMP id. However, now that we have entries in the flow table for ping flows, finding that is sufficient to get everything else we want, including the id. Therefore remove the icmp_epoll_ref type and use the general 'flowside' field for ping sockets. Having done this we no longer need separate EPOLL_TYPE_ICMP and EPOLL_TYPE_ICMPV6 reference types, because we can easily determine which case we have from the flow type. Merge both types into EPOLL_TYPE_PING. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: move IP stuff from util.[ch] to ip.[ch]Laurent Vivier2024-03-061-55/+0
| | | | | | | | | | | | Introduce ip.[ch] file to encapsulate IP protocol handling functions and structures. Modify various files to include the new header ip.h when it's needed. Signed-off-by: Laurent Vivier <lvivier@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au> Message-ID: <20240303135114.1023026-5-lvivier@redhat.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Add write_remainder() helperDavid Gibson2024-02-291-0/+35
| | | | | | | | | | | | | | | | | We have several places where we want to write(2) a buffer or buffers and we handle short write()s by retrying until everything is successfully written. Add a helper for this in util.c. This version has some differences from the typical write_all() function. First, take an IO vector rather than a single buffer, because that will be useful for some of our cases. Second, allow it to take an parameter to skip the first n bytes of the given buffers. This will be useful for some of the cases we want, and also falls out quite naturally from the implementation. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> [sbrivio: Minor formatting fixes in write_remainder()] Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Use sa_family_t for address family variablesDavid Gibson2024-02-271-1/+1
| | | | | | | | | | Sometimes we use sa_family_t for variables and parameters containing a socket address family, other times we use a plain int. Since sa_family_t is what's actually used in struct sockaddr and friends, standardise on that. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Make a bunch of pointer variables pointers to constDavid Gibson2024-01-161-2/+2
| | | | | | | | | | Sufficiently recent cppcheck (I'm using 2.13.0) seems to have added another warning for pointer variables which could be pointer to const but aren't. Use this to make a bunch of variables const pointers where they previously weren't for no particular reason. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Make sock_l4() treat empty string ifname like NULLDavid Gibson2023-12-271-1/+1
| | | | | | | | | | | sock_l4() takes NULL for ifname if you don't want to bind the socket to a particular interface. However, for a number of the callers, it's more natural to use an empty string for that case. Change sock_l4() to accept either NULL or an empty string equivalently, and simplify some callers using that change. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Avoid in_addr_tDavid Gibson2023-12-271-1/+1
| | | | | | | | | | | | | | | IPv4 addresses can be stored in an in_addr_t or a struct in_addr. The former is just a type alias to a 32-bit integer, so doesn't really give us any type checking. Therefore we generally prefer the structure, since we mostly want to treat IP address as opaque objects. Fix a few places where we still use in_addr_t, but can just as easily use struct in_addr. Note there are still some uses of in_addr_t in conf.c, but those are justified: since they're doing prefix calculations, they actually need to look at the internals of the address as an integer. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Drop explicit setting to INADDR_ANY/in6addr_any in sock_l4()David Gibson2023-12-271-4/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The original commit message says: --- Currently we initialise the address field of the sockaddrs we construct to the any/unspecified address, but not in a very clear way: we use explicit 0 values, which is only interpretable if you know the order of fields in the sockaddr structures. Use explicit field names, and explicit initialiser macros for the address. Because we initialise to this default value, we don't need to explicitly set the any/unspecified address later on if the caller didn't pass an overriding bind address. --- and the original patch modified the initialisation of addr4 and addr6: - instead of { 0 }, { 0 } for sin_addr and sin_zero, .sin_addr = IN4ADDR_ANY_INIT - instead of 0, IN6ADDR_ANY_INIT, 0: .sin6_addr = IN6ADDR_ANY_INIT but I dropped those hunks: they break gcc versions 7 to 9 as reported in eed6933e6c29 ("udp: Explicitly initialise sin6_scope_id and sin_zero in sockaddr_in{,6}"). I applied the rest of the changes. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> [sbrivio: Dropped first two hunks] Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* port_fwd, util: Don't bind UDP ports with opposite-side bound TCP portsStefano Brivio2023-11-221-0/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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/+53
| | | | | | | | | | 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 Gibson2023-11-071-64/+1
| | | | | | | | | | | | | 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/+3
| | | | | | | | | 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>
* Avoid shadowing index(3)David Gibson2023-09-271-6/+6
| | | | | | | | | | | | | | | | | 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>
* epoll: Split handling of listening TCP sockets into their own handlerDavid Gibson2023-08-131-1/+1
| | | | | | | | | | | | | | | | | tcp_sock_handler() handles both listening TCP sockets, and connected TCP sockets, but what it needs to do in those cases has essentially nothing in common. Therefore, give listening sockets their own epoll_type value and dispatch directly to their own handler from the top level. Furthermore, the two handlers need essentially entirely different information from the reference: we re-(ab)used the index field in the tcp_epoll_ref to indicate the port for the listening socket, but that's not the same meaning. So, switch listening sockets to their own reference type which we can lay out as we please. That lets us remove the listen and outbound fields from the normal (connected) tcp_epoll_ref, reducing it to just the connection table index. 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 Gibson2023-08-131-7/+20
| | | | | | | | | | | | | | 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>
* util: Make ns_enter() a void function and report setns() errorsDavid Gibson2023-08-041-5/+3
| | | | | | | | | | | | | | | | 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>
* Use C11 anonymous members to make poll refs less verbose to useDavid Gibson2023-08-041-2/+2
| | | | | | | | | | | | 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>
* util, conf: Add and use ns_is_init() helperStefano Brivio2023-05-231-0/+25
| | | | | | | | | | 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>
* tcp, udp, util: Pass socket creation errors all the way upStefano Brivio2023-03-091-13/+18
| | | | | | | | | ...starting from sock_l4(), pass negative error (errno) codes instead of -1. They will only be used in two commits from now, no functional changes intended here. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* treewide: Fix header includes to build with muslChris Kuhn2023-03-091-0/+1
| | | | | | | | | | | | | | | 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>
* util: Add own prototype for __clone2() on ia642023_02_27.c538ee8Stefano Brivio2023-02-271-0/+9
| | | | | | | | | | | | | ia64 needs to use __clone2() as clone() is not available, but glibc doesn't export the prototype. Take it from clone(2) to avoid an implicit declaration: util.c: In function ‘do_clone’: util.c:512:16: warning: implicit declaration of function ‘__clone2’ [-Wimplicit-function-declaration] 512 | return __clone2(fn, stack_area + stack_size / 2, stack_size / 2, | ^~~~~~~~ Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Make assertions actually usefulDavid Gibson2023-02-121-1/+0
| | | | | | | | | | | | | | | | | | 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>
* util: Always return -1 on error in sock_l4()David Gibson2022-11-251-1/+1
| | | | | | | | | According to its doc comments, sock_l4() returns -1 on error. It does, except in one case where it returns -EIO. Fix this inconsistency to match the docs and always return -1. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Allow sock_l4() to open dual stack socketsDavid Gibson2022-11-251-2/+15
| | | | | | | | | | | | | | | Currently, when instructed to open an IPv6 socket, sock_l4() explicitly sets the IPV6_V6ONLY socket option so that the socket will only respond to IPv6 connections. Linux (and probably other platforms) allow "dual stack" sockets: IPv6 sockets which can also accept IPv4 connections. Extend sock_l4() to be able to make such sockets, by passing AF_UNSPEC as the address family and no bind address (binding to a specific address would defeat the purpose). We add a Makefile define 'DUAL_STACK_SOCKETS' to indicate availability of this feature on the target platform. 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 Brivio2022-11-161-0/+21
| | | | | | | | | | | | | | | 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>
* arp, tap, util: Don't use perror() after seccomp filter is installedStefano Brivio2022-11-161-3/+3
| | | | | | | | | | | | | | | If stderr is closed, after we fork to background, glibc's implementation of perror() will try to re-open it by calling dup(), upon which the seccomp filter causes the process to terminate, because dup() is not included in the list of allowed syscalls. Replace perror() calls that might happen after isolation_postfork(). We could probably replace all of them, but early ones need a bit more attention as we have to check whether log.c functions work in early stages. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* Replace FWRITE with a functionDavid Gibson2022-10-151-0/+33
| | | | | | | | | | | | | | 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>
* conf, tcp, udp: Allow specification of interface to bind toStefano Brivio2022-10-151-1/+18
| | | | | | | | | | | | | | | | 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>
* util: Check return value of lseek() while reading bound ports from procfsStefano Brivio2022-10-151-3/+7
| | | | | | | | | Coverity now noticed we're checking most lseek() return values, but not this. Not really relevant, but it doesn't hurt to check we can actually seek before reading lines. 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 Brivio2022-10-141-120/+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>
* clang-tidy: Suppress warning about unchecked error in logfn macroDavid Gibson2022-09-291-1/+1
| | | | | | | | | clang-tidy complains that we're not checking the result of vfprintf in logfn(). There's not really anything we can do if this fails here, so just suppress the error with a cast to void. 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 Gibson2022-09-131-5/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 Gibson2022-09-131-51/+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 Gibson2022-09-131-50/+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 Gibson2022-09-131-3/+26
| | | | | | | | | | | | | | | | | | 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>
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