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* conf, tcp, udp: Allow specification of interface to bind toStefano Brivio2022-10-151-10/+21
| | | | | | | | | | | | | | | | 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, tap: Add option to quit once the client closes the connectionStefano Brivio2022-10-151-1/+16
| | | | | | | | This is practical to avoid explicit lifecycle management in users, e.g. libvirtd, and is trivial to implement. 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>
* log, conf: Add support for logging to fileStefano Brivio2022-10-141-3/+46
| | | | | | | | | | | | | | | | | | | | | | 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>
* conf: Drop duplicate, diverging optstring assignmentsStefano Brivio2022-10-141-14/+6
| | | | | | | | | | | | | This originated as a result of copy and paste to introduce a second stage for processing options related to port forwarding, has already bitten David in the past, and just gave me hours of fun. As a matter of fact, the second set of optstring assignments was already incorrect, but it didn't matter because the first one was more restrictive, not allowing optional arguments for -P, -D, -S. 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: Use inline suppression for strtok() in conf.cDavid Gibson2022-09-291-0/+2
| | | | | | | | | | | strtok() is non-reentrant and old-fashioned, so cppcheck would complains about its use in conf.c if it weren't suppressed. We're single threaded and strtok() is convenient though, so it's not really worth reworking at this time. Convert this to an inline suppression so it's adjacent to the code its annotating. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Don't shadow 'i' in conf_ports()David Gibson2022-09-291-2/+5
| | | | | | | | | | | | | | The counter 'i' is used in a number of places in conf_ports(), but in one of those we unnecessarily shadow it in an inner scope. We could re-use the same 'i' every time, but each use is logically separate, so instead remove the outer declaration and declare it locally in each of the clauses where we need it. While we're there change it from a signed to unsigned int, since it's used to iterate over port numbers which are generally treated as unsigned. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Clean up parsing in conf_runas()David Gibson2022-09-291-45/+50
| | | | | | | | | | | | | | | | | | | | | | | | | conf_runas() handles several of the different possible cases for the --runas argument in a slightly odd order. Although it can parse both numeric UIDs/GIDs and user/group names, it can't parse a numeric UID combined with a group name or vice versa. That's not obviously useful, but it's slightly surprising gap to have. Rework the parsing to be more systematic: first split the option into user and (optional) group parts, then separately parse each part as either numeric or a name. As a bonus this removes some clang-tidy warnings. While we're there also add cppcheck suppressions for getpwnam() and getgrnam(). It complains about those because they're not reentrant. passt is single threaded though, and is always likely to be during this initialization code, even if we multithread later. There were some existing suppressions for these in the cppcheck invocation but they're no longer up to date. Replace them with inline suppressions which, being next to the code, are more likely to stay correct. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Clean up parsing of port rangesDavid Gibson2022-09-291-140/+102
| | | | | | | | | | | | | | | | | | | | conf_ports() parses ranges of ports for the -t, -u, -T and -U options. The code is quite difficult to the follow, to the point that clang-tidy and cppcheck disagree on whether one of the pointers can be NULL at some points. Rework the code with the use of two new helper functions: * parse_port_range() operates a bit like strtoul(), but can parse a whole port range specification (e.g. '80' or '1000-1015') * next_chunk() does the necessary wrapping around strchr() to advance to just after the next given delimiter, while cleanly handling if there are no more delimiters The new version is easier to follow, and also removes some cppcheck warnings. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Fix widespread off-by-one error dealing with port numbersDavid Gibson2022-09-241-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | Port numbers (for both TCP and UDP) are 16-bit, and so fit exactly into a 'short'. USHRT_MAX is therefore the maximum port number and this is widely used in the code. Unfortunately, a lot of those places don't actually want the maximum port number (USHRT_MAX == 65535), they want the total number of ports (65536). This leads to a number of potentially nasty consequences: * We have buffer overruns on the port_fwd::delta array if we try to use port 65535 * We have similar potential overruns for the tcp_sock_* arrays * Interestingly udp_act had the correct size, but we can calculate it in a more direct manner * We have a logical overrun of the ports bitmap as well, although it will just use an unused bit in the last byte so isnt harmful * Many loops don't consider port 65535 (which does mitigate some but not all of the buffer overruns above) * In udp_invert_portmap() we incorrectly compute the reverse port translation for return packets Correct all these by using a new NUM_PORTS defined explicitly for this purpose. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Treat port numbers as unsignedDavid Gibson2022-09-241-5/+6
| | | | | | | | | | | Port numbers are unsigned values, but we're storing them in (signed) int variables in some places. This isn't actually harmful, because int is large enough to hold the entire range of ports. However in places we don't want to use an in_port_t (usually to avoid overflow on the last iteration of a loop) it makes more conceptual sense to use an unsigned int. This will also avoid some problems with later cleanups. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Pass entire port forwarding configuration substructure to conf_ports()David Gibson2022-09-241-40/+22
| | | | | | | | | conf_ports() switches on the optname argument to select the target array for several updates. Now that all these maps are in a common structure, we can simplify by just passing in a pointer to the whole struct port_fwd to update. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Don't use indirect remap functions for conf_ports()David Gibson2022-09-241-7/+7
| | | | | | | | | | Now that we've delayed initialization of the UDP specific "reverse" map until udp_init(), the only difference between the various 'remap' functions used in conf_ports() is which array they target. So, simplify by open coding the logic into conf_ports() with a pointer to the correct mapping array. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Consolidate port forwarding configuration into a common structureDavid Gibson2022-09-241-37/+37
| | | | | | | | | | | | | | | The configuration for how to forward ports in and out of the guest/ns is divided between several different variables. For each connect direction and protocol we have a mode in the udp/tcp context structure, a bitmap of which ports to forward also in the context structure and an array of deltas to apply if the outward facing and inward facing port numbers are different. This last is a separate global variable, rather than being in the context structure, for no particular reason. UDP also requires an additional array which has the reverse mapping used for return packets. Consolidate these into a re-used substructure in the context structure. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Improve types and names for port forwarding configurationDavid Gibson2022-09-241-36/+37
| | | | | | | | | | | | | | | | | | | | | | | | | enum conf_port_type is local to conf.c and is used to track the port forwarding mode during configuration. We don't keep it around in the context structure, however the 'init_detect_ports' and 'ns_detect_ports' fields in the context are based solely on this. Rather than changing encoding, just include the forwarding mode into the context structure. Move the type definition to a new port_fwd.h, which is kind of trivial at the moment but will have more stuff later. While we're there, "conf_port_type" doesn't really convey that this enum is describing how port forwarding is configured. Rename it to port_fwd_mode. The variables (now fields) of this type also have mildly confusing names since it's not immediately obvious whether 'ns' and 'init' refer to the source or destination of the packets. Use "in" (host to guest / init to ns) and "out" (guest to host / ns to init) instead. This has the added bonus that we no longer have locals 'udp_init' and 'tcp_init' which shadow global functions. In addition, add a typedef 'port_fwd_map' for a bitmap of each port number, which is used in several places. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* conf, tcp, udp: Arrays for ports need 2^16 values, not 2^16-8Stefano Brivio2022-09-221-1/+1
| | | | | | | | | | | | Reported by David but also by Coverity (CWE-119): In conf_ports: Out-of-bounds access to a buffer ...not in practice, because the allocation size is rounded up anyway, but not nice either. Reported-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Allow --userns when pasta spawns a commandDavid Gibson2022-09-131-5/+0
| | | | | | | | | | | | Currently --userns is only allowed when pasta is attaching to an existing netns or PID, and is prohibited when creating a new netns by spawning a command or shell. With the new handling of userns, this check isn't neccessary. I'm not sure if there's any use case for --userns with a spawned command, but it's strictly more flexible and requires zero extra code, so we might as well. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Handle userns isolation and dropping root at the same timeDavid Gibson2022-09-131-5/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* Clean up and rename conf_ns_open()David Gibson2022-09-131-71/+1
| | | | | | | | | | | | | | conf_ns_open() opens file descriptors for the namespaces pasta needs, but it doesnt really have anything to do with configuration any more. For better clarity, move it to pasta.c and rename it pasta_open_ns(). This makes the symmetry between it and pasta_start_ns() more clear, since these represent the two basic ways that pasta can operate, either attaching to an existing namespace/process or spawning a new one. Since its no longer validating options, the errors it could return shouldn't cause a usage message. Just exit directly with an error instead. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Consolidate validation of pasta namespace optionsDavid Gibson2022-09-131-41/+42
| | | | | | | | | | | | | | | | | | | | There are a number of different ways to specify namespaces for pasta to use. Some combinations are valid and some are not. Currently validation for these is spread across several places: conf_ns_pid() validates PID options specifically. Near its callsite in conf() several other checks are made. Some additional checks are made in conf_ns_open() and finally theres a check just before the call to pasta_start_ns(). This is quite hard to follow. Make it easier by putting all the validation logic together in a new conf_pasta_ns() function, which subsumes conf_ns_pid(). This reveals that some of the checks were redundant with each other, so remove those. For good measure, rename conf_netns() to conf_netns_opt() to make it clearer its handling just the --netns option specifically, not overall configuration of the netns. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Move self-isolation code into a separate fileDavid Gibson2022-09-131-0/+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>
* Safer handling if we can't open /proc/self/uid_mapDavid Gibson2022-09-131-2/+6
| | | | | | | | | | | | | | | | | passt is allowed to run as "root" (UID 0) in a user namespace, but notas real root in the init namespace. We read /proc/self/uid_map to determine if we're in the init namespace or not. If we're unable to open /proc/self/uid_map we assume we're ok and continue running as UID 0. This seems unwise. The only instances I can think of where uid_map won't be available are if the host kernel doesn't support namespaces, or /proc is not mounted. In neither case is it safe to assume we're "not really" root and continue (although in practice we'd likely fail for other reasons pretty soon anyway). Therefore, fail with an error in this case, instead of carrying on. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Consolidate determination of UID/GID to run asDavid Gibson2022-09-131-8/+73
| | | | | | | | | | | | 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 Gibson2022-09-131-2/+3
| | | | | | | | | | | | | | | | | | 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 Gibson2022-09-131-3/+5
| | | | | | | | 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>
* conf: Fix getopt_long() optstring for current semantics of -D, -S, -pStefano Brivio2022-09-021-2/+2
| | | | | | | | | | | | | Declaring them as required_argument in the longopts array specifies validation, but doesn't affect how optind is increased after parsing their values. Currently, passing one of these options as last option causes pasta to handle their own values as path to a binary to execute. Fixes: aae2a9bbf7d1 ("conf: Use "-D none" and "-S none" instead of missing empty option arguments") Fixes: bf95322fc1ef ("conf: Make the argument to --pcap option mandatory") Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Allow pasta to take a command to executeDavid Gibson2022-08-301-9/+18
| | | | | | | | | | | | | | When not given an existing PID or network namspace to attach to, pasta spawns a shell. Most commands which can spawn a shell in an altered environment can also run other commands in that same environment, which can be useful in automation. Allow pasta to do the same thing; it can be given an arbitrary command to run in the network and user namespace which pasta creates. If neither a command nor an existing PID or netns to attach to is given, continue to spawn a default shell, as before. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Use explicit --netns option rather than multiplexing with PIDDavid Gibson2022-08-301-25/+60
| | | | | | | | | | | | When attaching to an existing namespace, pasta can take a PID or the name or path of a network namespace as a non-option parameter. We disambiguate based on what the parameter looks like. Make this more explicit by using a --netns option for explicitly giving the path or name, and treating a non-option argument always as a PID. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> [sbrivio: Fix typo in man page] Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* More deterministic detection of whether argument is a PID, PATH or NAMEDavid Gibson2022-08-301-82/+90
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | pasta takes as its only non-option argument either a PID to attach to the namespaces of, a PATH to a network namespace or a NAME of a network namespace (relative to /run/netns). Currently to determine which it is we try all 3 in that order, and if anything goes wrong we move onto the next. This has the potential to cause very confusing failure modes. e.g. if the argument is intended to be a network namespace name, but a (non-namespace) file of the same name exists in the current directory. Make behaviour more predictable by choosing how to treat the argument based only on the argument's contents, not anything else on the system: - If it's a decimal integer treat it as a PID - Otherwise, if it has no '/' characters, treat it as a netns name (ip-netns doesn't allow '/' in netns names) - Otherwise, treat it as a netns path If you want to open a persistent netns in the current directory, you can use './netns'. This also allows us to split the parsing of the PID|PATH|NAME option from the actual opening of the namespaces. In turn that allows us to put the opening of existing namespaces next to the opening of new namespaces in pasta_start_ns. That makes the logical flow easier to follow and will enable later cleanups. Caveats: - The separation of functions mean we will always generate the basename and dirname for the netns_quit system, even when using PID namespaces. This is pointless, since the netns_quit system doesn't work for non persistent namespaces, but is harmless. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Move ENOENT error message into conf_ns_opt()David Gibson2022-08-301-2/+1
| | | | | | | | After calling conf_ns_opt() we check for -ENOENT and print an error message, but conf_ns_opt() prints messages for other errors itself. For consistency move the ENOENT message into conf_ns_opt() as well. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Remove --nsrun-dir optionDavid Gibson2022-08-301-20/+4
| | | | | | | | | | | | | pasta can identify a netns as a "name", which is to say a path relative to (usually) /run/netns, which is the place that ip(8) creates persistent network namespaces. Alternatively a full path to a netns can be given. The --nsrun-dir option allows the user to change the standard path where netns names are resolved. However, there's no real point to this, if the user wants to override the location of the netns, they can just as easily use the full path to specify the netns. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* conf: Use "-D none" and "-S none" instead of missing empty option argumentsDavid Gibson2022-08-301-24/+32
| | | | | | | | | | | | | | | | Both the -D (--dns) and -S (--search) options take an optional argument. If the argument is omitted the option is disabled entirely. However, handling the optional argument requires some ugly special case handling if it's the last option on the command line, and has potential ambiguity with non-option arguments used with pasta. It can also make it more confusing to read command lines. Simplify the logic here by replacing the non-argument versions with an explicit "-D none" or "-S none". Signed-off-by: David Gibson <david@gibson.dropbear.id.au> [sbrivio: Reworked logic to exclude redundant/conflicting options] Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* conf: Make the argument to --pcap option mandatoryDavid Gibson2022-08-301-15/+3
| | | | | | | | | | | The --pcap or -p option can be used with or without an argument. If given, the argument gives the name of the file to save a packet trace to. If omitted, we generate a default name in /tmp. Generating the default name isn't particularly useful though, since making a suitable name can easily be done by the caller. Remove this feature. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Don't unnecessarily avoid CLOEXEC flags2022_08_24.60ffc5bDavid Gibson2022-08-241-7/+3
| | | | | | | | | | | | | | | | 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>
* conf: Fix incorrect bounds checking for sock_path parameterDavid Gibson2022-08-241-1/+1
| | | | | | | Looks like a copy-paste error where we're checking against the size of the pcap field, rather than the sock_path field. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Make substructures for IPv4 and IPv6 specific context informationDavid Gibson2022-07-301-90/+94
| | | | | | | | | | | | 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 Gibson2022-07-301-68/+80
| | | | | | | | | | | | | | | | | | | 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>
* Clarify semantics of c->v4 and c->v6 variablesDavid Gibson2022-07-301-39/+20
| | | | | | | | | | | | | | | | | | | | | 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>
* Move passt mac_guest init to be more symmetric with pastaDavid Gibson2022-07-301-3/+0
| | | | | | | | | | | | | | | | | In pasta mode, the guest's MAC address is set up in pasta_ns_cobf() called from tap_sock_tun_init(). If we have a guest MAC configured with --ns-mac-addr, this will set the given MAC on the kernel tuntap device, or if we haven't configured one it will update our record of the guest MAC to the kernel assigned one from the device. For passt, we don't initially know the guest's MAC until we receive packets from it, so we have to initially use a broadcast address. This is - oddly - set up in an entirely different place, in conf_ip() conditional on the mode. Move it to the logically matching place for passt - tap_sock_unix_init(). Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Initialize host side MAC when in IPv6 only modeDavid Gibson2022-07-301-9/+12
| | | | | | | | | | | | | | | | | | When sending packets to the guest we need a source MAC address, which we currently take from the host side interface we're using (though it's basically arbitrary). However if not given on the command line this MAC is initialized in an IPv4 specific path, and will end up as 00:00:00:00:00:00 when running "passt 6". The MAC address is also used for IPv6 packets, though. Interestingly, we largely seem to get away with using an all-zero MAC, but it's probably not a good idea. Make the IPv6 path pick the MAC address from its interface if the IPv4 path hasn't already done so. While we're there, use the existing MAC_IS_ZERO macro to make the code a little clearer. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Separately locate external interfaces for IPv4 and IPv6David Gibson2022-07-301-2/+17
| | | | | | | | | | | | | | | | | Now that the back end allows passt/pasta to use different external interfaces for IPv4 and IPv6, use that to do the right thing in the case that the host has IPv4 and IPv6 connectivity via different interfaces. If the user hasn't explicitly chosen an interface, separately search for a suitable external interface for each protocol. As a bonus, this substantially simplifies the external interface probe. It also eliminates a subtle confusing case where in some circumstances we would pick the first interface in interface index order, and sometimes in order of routes returned from netlink. On some network configurations that could cause tests to fail, because the logic in the tests was subtly different (it always used route order). Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Allow different external interfaces for IPv4 and IPv6 connectivityDavid Gibson2022-07-301-17/+21
| | | | | | | | | | | | | | | | It's quite plausible for a host to have both IPv4 and IPv6 connectivity, but only via different interfaces. For example, this will happen in the case that IPv6 connectivity is via a tunnel (e.g. 6in4 or 6rd). It would also happen in the case that IPv4 access is via a tunnel on an otherwise IPv6 only local network, which is a setup that might become more common in the post IPv4 address exhaustion world. In turns out there's no real need for passt/pasta to get its IPv4 and IPv6 connectivity via the same interface, so we can handle this situation fairly easily. Change the core to allow eparate external interfaces for IPv4 and IPv6. We don't actually set these separately for now. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* conf: Reset range endpoints after parsing one excluded port specifier2022_07_14.b86cd00Stefano Brivio2022-07-141-0/+1
| | | | | | | | | I forgot to reset the range endpoints after parsing an item of the comma-separated list in commit 220759efb89a ("conf: Allow to specify ranges and ports excluded from given ranges") -- fix that. Fixes: 220759efb89a ("conf: Allow to specify ranges and ports excluded from given ranges") Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* conf: Allow to specify ranges and ports excluded from given rangesStefano Brivio2022-07-141-11/+101
| | | | | | | | | | | | | | | | | | | | | This is useful in environments where we want to forward a large number of ports, or all non-ephemeral ones, and some other service running on the host needs a few selected ports. I'm using ~ as prefix for the specification of excluded ranges and ports to avoid the need for explicit command line quoting. Ranges and ports can be excluded from given ranges by adding them in the comma-separated list, prefixed by ~. Some quick examples: -t 5000-6000,~5555: forward ports 5000 to 6000, but not 5555 -t ~20000-20010: forward all non-ephemeral, allowed ports, except for ports 20000 to 20010 ...more details in usage message and man page. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* conf: Fix initialisation of IPv6 unicast and link-local addressesStefano Brivio2022-07-141-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | In commit 675174d4ba25 ("conf, tap: Split netlink and pasta functions, allow interface configuration"), I broke the initial setting of the observed IPv6 addresses in two ways: - the size copied from the configured addresses corresponds to an IPv4 address, not to an IPv6 address - the observed link-local address is initialised to the configured unicast address, not the link-local one If we haven't seen the guest using some type of addresses yet, we should default to the configured values, hence these initial settings: fix both. This resulted in UDP flows to the guest from a unique local address on the network not working before the guest shows passt a valid address itself, as reported by Alona. Reported-by: Alona Paz <alkaplan@redhat.com> Link: https://bugs.passt.top/show_bug.cgi?id=16 Fixes: 675174d4ba25 ("conf, tap: Split netlink and pasta functions, allow interface configuration") Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Handle the case of a DNS server on localhostDavid Gibson2022-07-141-0/+16
| | | | | | | | | | | | | | | | | | By default, passt detects the nameserver used by the host system by reading /etc/resolv.conf, and advertises that to the guest via DHCP. However this breaks down if the host's nameserver is local (on 127.0.0.1 or ::1); connecting to localhost on the guest won't reach the host's nameserver. Using a local nameserver is a reasonably common case when using dnsmasq or similar to merge name resolution on a home network with name resolution from an organization-private VPN. We already have the gateway mapping support to allow reaching host-local services from the guest via the address of the default gateway. Add code to detect the case of a local DNS server and use the gateway mapping to advertise it usefully to the guest. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Parse resolv.conf with new lineread implementationDavid Gibson2022-07-061-8/+14
| | | | | | | | | | | Switch the resolv.conf parsing in conf.c to use the new lineread implementation. This means that it can now handle a resolv.conf file which contains blank lines. There are quite a few other fragilities with the resolv.conf parsing, but that's out of scope for this patch. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* conf: In conf_runas(), on static builds, group information is also unusedStefano Brivio2022-06-181-0/+1
| | | | Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* conf: Fix one Coverity CID 258163 warning, work around another oneStefano Brivio2022-05-201-5/+3
| | | | | | | | | | | | | | | In conf_runas(), Coverity reports that we might dereference uid and gid despite possibly being NULL (CWE-476) because of the check after the first sscanf(). They can't be NULL, but I actually wanted to check that UID and GID are non-zero (the user could otherwise pass --runas root:root and defy the whole mechanism). Later on, we have the same type of warning for 'gr': it's compared against NULL, so it might be NULL, which is actually the case: but in that case, we don't dereference it, because we'll return -ENOENT right away. Rewrite the clause to silence the warning. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>