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* executor: tolerate syz_genetlink_get_family_id failuresAleksandr Nogikh2022-02-251-4/+1
| | | | | | | | | | We cannot expect syscalls to always succeed during fuzzing, especially when the situation involves a complex interaction with the system. For the syz_genetlink_get_family_id case, it leads to numerous SYZFAIL crashes every day. Don't print a SYZFAIL error for this pseudo syscall.
* fix: "mmap_alloc_size"->"cov->mmap_alloc_size"aiQG_2022-02-211-1/+1
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* executor: fail on SEGV during clone()Aleksandr Nogikh2022-01-214-1/+40
| | | | | | | | | | | | | | | As was found out in #2921, fork bombs are still possible in Linux-based instances. One of the possible reasons is described below. An invalid stack can be passed to the clone() call, thus causing it to stumble on an invalid memory access right during returning from the clone() call. This is in turn catched by the NONFAILING() macro and the control actually jumps over it and eventually both the child and the parent continue executing the same code. Prevent it by handling SIGSEGV and SIGBUS differently during the clone process. Co-authored-by: Andrei Vagin <avagin@google.com>
* executor: add extension point for adding non-mainline pseudo-syscallsDmitry Vyukov2022-01-192-0/+8
| | | | | | | | | | Add an empty common_ext.h which is included into executor and C reproducers and can be used to add non-mainline pseudo-syscalls w/o changing any other files (by replacing common_ext.h file). It would be good to finish #2274 which allows to add pseudo-syscalls along with *.txt descriptions, but #2274 is large and there are several open design questions. So add this simple extension point for now.
* all: create 8 tun devices for OpenBSDAleksandr Nogikh2022-01-141-2/+2
| | | | | Currently only 4 are created by default. This limits the maximum number of simultaneously running syz-executors.
* all: add syz_clone() and syz_clone3() pseudo callsAleksandr Nogikh2022-01-131-0/+59
| | | | | | | | | | | | | | | | | | | | As was pointed out in #2921, the current approach of limiting the number of pids per process does not work on all Linux-based kernels. We could just treat fork, clone and clone3 in a special way (e.g. exit on a zero return). However, in that case we also need to sanitize the arguments for clone and clone3 - if CLONE_VM is passed and stack is 0, the forked child processes (threads) will become nearly unindentifiable and will corrupt syz-executor's memory. While we could sanitize clone's arguments, we cannot do so for clone3 - nothing can guarantee that they will not be changed concurrently. Instead of calling those syscalls directly, introduce a special pseudo syscall syz_clone3. It copies and sanitizes the arguments and then executes clone3 (or fork, if we're on an older kernel) in such a way so as to prevent fork bombs from happening. Also introduce syz_clone() to still be able to fuzz it on older systems.
* executor: remove custom sys_io_uring_setup definitionAleksandr Nogikh2022-01-131-7/+1
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* executor: remove sys_memfd_create definesAleksandr Nogikh2022-01-131-19/+1
| | | | | Add memfd_create as a dependency to syz_mount_image and syz_read_part_table.
* executor: move SYSCALL_DEFINES above common_*.h includesAleksandr Nogikh2022-01-131-1/+4
| | | | | Otherwise the pseudo syscalls there won't be able to access those definitions.
* sys/syz-sysgen: generate possibly missing __NR/SYS definesAleksandr Nogikh2022-01-131-0/+1
| | | | | | | | | As the comiling machine may have a kernel version different from the tested one, not all definitions might be present. Generate sequences of ifndef in defs.h to avoid potential issues. Restrict __NR-related style checking rules to only checking common*.h files.
* executor: don't print errno for successful callsDmitry Vyukov2022-01-111-5/+7
| | | | Don't print the confuing errno 14 for successful calls.
* executor: bump on FreeBSD the maximum number of tun devices to 256 (#2956)Michael Tüxen2021-12-311-0/+5
| | | | | | | syz-execprog now uses twice the number of CPU cores as the number of processes. Each process might use a tun device. So bump the maximum number of tun devices to the maximum of 256, which allows syz-execprog to run with default settings on systems with up to 128 cores.
* executor: support larger maximum number of tun devices on *BSD (#2953)Michael Tüxen2021-12-301-9/+17
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* executor: ignore async flag in the non-threaded modeAleksandr Nogikh2021-12-131-3/+3
| | | | | | | | pkg/repro tries to clear the Threaded flag during repro simplification, so it's easier just to ignore the remaining async flags in that case - they won't be in the C repro either. Add a test to pkg/ipc to verify the new behavior.
* executor: do exitf instead of fail on kcov shortageAleksandr Nogikh2021-12-101-2/+2
| | | | | | | | | Set new kcov count limits: 6 for the default mode and 16 for the optimized mode (when the instances are mmapped a needed). Don't generate SYZFAIL when these limits are exhausted. Just increasing those limits won't help as syzkaller will anyway come up with programs that overcome them.
* all: add the `rerun` call propertyAleksandr Nogikh2021-12-101-0/+9
| | | | | | | | | | | | | | To be able to collide specific syscalls more precisely, we need to repeat the process many times. Introduce the `rerun` call property, which instructs `syz-executor` to repeat the call the specified number of times. The intended use is: call1() (rerun: 100, async) call2() (rerun: 100) For now, assign rerun values randomly to consecutive pairs of calls, where the first one is async.
* all: replace collide mode by `async` call propertyAleksandr Nogikh2021-12-102-110/+86
| | | | | | | | | | | | | Replace the currently existing straightforward approach to race triggering (that was almost entirely implemented inside syz-executor) with a more flexible one. The `async` call property instructs syz-executor not to block until the call has completed execution and proceed immediately to the next call. The decision on what calls to mark with `async` is made by syz-fuzzer. Ultimately this should let us implement more intelligent race provoking strategies as well as make more fine-grained reproducers.
* executor: fix kcov mmaping in the non-optimized modeAleksandr Nogikh2021-12-091-2/+0
| | | | | As all opened kcov instances are mmapped, we don't need to check it one more time at all.
* all: adapt to how mmapping a kcov instance works in LinuxAleksandr Nogikh2021-12-091-4/+22
| | | | | | | | | | | | | | | | | | | | It turns out that the current Linux implementation of KCOV does not properly handle multiple mmap invocations on the same instance. The first one succeedes, but the subsequent ones do not actually mmap anything, yet returning no error at all. The ability to mmap that memory multiple times allows us to increase syz-executor performance and it would be a pity to completely lose it (especially given that mmapping kcov works fine on *BSD). In some time a patch will be prepared, but still we will have to support both versions at the same time - the buggy one and the correct one. Detect whether the bug is present by writing a value at the pointer returned by mmap. If it is present, disable dynamic kcov mmapping and pre-mmap 5 instances in the main() function - it should be enough for all reasonable uses. Otherwise, pre-mmap 3 and let syz-executor mmap them as needed.
* executor: spread overlapping fdsAleksandr Nogikh2021-12-062-4/+4
| | | | | | | There's a chance that the methods from common_bsd.h and common_linux.h could dup2 (and thus close) an fd belonging to a kcov instance. Prevent this by adjusting fd consts.
* executor: set fixed fd for the extra coverage kcov instanceAleksandr Nogikh2021-12-061-0/+2
| | | | | Currently it is dup2'd to 0, which is quite likely to be closed by the fuzzer. Dup2 it to a safer fd instead.
* executor: delay kcov mmap until it is neededAleksandr Nogikh2021-12-035-56/+46
| | | | | | | | | The previous strategy (delay kcov instance creation) seems not to work very well in carefully sandboxed environments. Let's see if the new approach is more versatile. Open a kcov handle for each thread at syz-executor's initialization, but don't mmap it right away.
* executor: reserve fds that will belong to kcovAleksandr Nogikh2021-12-035-3/+36
| | | | | | | | | As now kcov instances may get set up during fuzzing, performing dup2 in cover_open is no longer safe as it may close some important resource. Prevent that by reserving most of fds that belong to the kcov fds range. Unfortunately we must duplicate the code because of the way kcov implementations are organized.
* executor: allocate output region for individual programsAleksandr Nogikh2021-12-031-18/+79
| | | | | | | | | | | | | | | | | | | | The amount of virtual memory affects the speed of forking/exiting. As in most cases we do it for each executed program, the difference may be substantial. We don't need 16MB of output data for each execution (in fact, experiments have shown that we never cross even 8MB on Linux). But reducing that cap in more than 2 times is a pretty bold decision, and perhaps it's better to just make the allocation process smarter. Mmap the output region depending on the exact amount of memory needed for a specific program. E.g. if comparisons are collected, the expected amount of output is maximal. If we only collect signals, the output is minimal. Mmap the minimally required region in the parent and then re-mmap it in the forked child if it turns out that a higher amount of memory is needed.
* executor: introduce threads without coverageAleksandr Nogikh2021-12-031-6/+24
| | | | | | | | | | | | | | | | Experiments have shown that the amount of allocated memory has a very big impact on the syz-executor's performance (at least under Linux) - much bigger than was expected. One source of that extra virtual memory is kcov and, in fact, usually we don't need all 16 kcov handles we create. E.g. only 4 are enough for 99.5% progs that syzkaller executes. The biggest consumer of threads - the collide mode doesn't need kcov at all. Let kcov handle be an optional property of a thread, not a mandatory one. Allocate only 3 kcov instances initially (they'll be preserved over forks) and let the forked processes create other kcov instances if they happen to be needed.
* executor: changed initialization of VMCS fieldsAyomide Erinfolami2021-12-012-4/+4
| | | | | | | Initializing the VMCS fields Pin-based VM-execution controls and Primary processor-based VM-execution controls to 0 and setting their reserved bits using the appropriate MSRs increase coverage for arch/x86/kvm/vmx/nested.c from 19% to 43%.
* executor: add an ifdef SYZ_* style checkAleksandr Nogikh2021-11-301-0/+8
| | | | | | SYZ_* constants are always defined and one must not check them via ifdef. Add a check to prevent such problems during development (inspired by the discussion in #2882).
* executor: do not follow symlinks during umountAleksandr Nogikh2021-10-291-4/+4
| | | | | Add a UMOUNT_NOFOLLOW flag to umount2 in order to prevent remove_dir from unmounting what was not mounted by the executed program.
* all: add binderfs fuzzing supportAleksandr Nogikh2021-10-291-0/+38
| | | | | | | | Create one instance of binderfs per process and add descriptions to enable syzkaller to create binderfs mounts and binder devices itself. Keep descriptions compatible with the legacy mode (when devices are created at boot time).
* executor: don't mount some cgroup controllers during setupDmitry Vyukov2021-10-131-3/+3
| | | | | | | Leave some controllers unbound so that the fuzzer can mount them during fuzzing. This is suboptimal because all controllers are global (so different test processes will collide, state accumulate, etc), but this still should give at least some new coverage.
* executor: don't fail on cgroup mountingDmitry Vyukov2021-10-131-2/+6
| | | | | | | | | | | | | | | | On stretch images setup_cgroups fails as: mount(/syzcgroup/net, net) failed: 22 mount(/syzcgroup/net, net_cls) failed: 22 mount(/syzcgroup/net, net_prio) failed: 22 mount(/syzcgroup/net, blkio) failed: 22 SYZFAIL: mount cgroup failed (/syzcgroup/net, devices,freezer): 16 (errno 16: Device or resource busy) It seems that systemd starts messing with these mounts somehow and repeated mounting fails with EBUSY. Don't hard fail on that error.
* executor: setup cgroups onceDmitry Vyukov2021-10-124-7/+8
| | | | | | | Currently we setup cgroups on every test process start (along with sandbox creation). That's unnecessary because that's global per-machine setup. Move cgroup setup into setup section that's executed once per machine from pkg/host.Setup.
* executor: remove unused sysctl setupDmitry Vyukov2021-10-121-1/+0
| | | | | | | pkg/host.Setup never asks to setup "sysctl" feature explicitly, sysctl's are assumed to be setup whenever "syz-executor setup" is executed. Thus "sysctl" does not need to be present in the list of available things to setup.
* executor: enable cgroup controllers one-by-oneDmitry Vyukov2021-10-121-18/+49
| | | | | | | | Currently we enable all controllers at once. As the result if one of them fails (b/c of older kernel or not enabled configs), all will fail. Enable them one-by-one instead. This way we can support kernels that don't have all of the controllers.
* executor: mount new cgroupsDmitry Vyukov2021-10-121-2/+2
| | | | Mount net, blkio, rlimit cgroups.
* executor: work around clang-format issueDmitry Vyukov2021-10-051-4/+6
| | | | | | | | clang-format mis-formats #elif: https://bugs.llvm.org/show_bug.cgi?id=48664 and then clang fails with: error: misleading indentation; statement is not part of the previous 'if' Split #elif into nested #if/else.
* executor: check for single-line compound statementsDmitry Vyukov2021-10-017-16/+31
| | | | | | Historically the code base does not use single-line compound statements ({} around single-line blocks). But there are few precedents creeped into already. Add a check to keep the code base consistent.
* executor: fail if the first argument isn't a known commandAndrei Vagin2021-09-301-0/+5
| | | | | | | | | | | | | | | | | | We have seen cases when a test program re-execed the current binary: 11:53:29 executing program 0: openat$zero(0xffffffffffffff9c, &(0x7f0000000040), 0x0, 0x0) r0 = openat(0xffffffffffffff9c, &(0x7f0000000080)='/proc/self/exe\x00', 0x0, 0x0) lseek(r0, 0x4000000000000000, 0x4) execveat(r0, &(0x7f0000000080)='\x00', 0x0, 0x0, 0x1000) In such cases, we have to be sure that executor will not print SYZFAIL log messages and will not exit with kFailStatus. Since a659b3f1, syzkaller reports bugs in all these cases. Fixes: a659b3f1dc88 ("pkg/report: detect executor failures") Signed-off-by: Andrei Vagin <avagin@google.com>
* all: refactor fault injection into call propsAleksandr Nogikh2021-09-224-27/+30
| | | | | | | | | | | | Now that call properties mechanism is implemented, we can refactor fault injection. Unfortunately, it is impossible to remove all traces of the previous apprach. In reprolist and while performing syz-ci jobs, syzkaller still needs to parse the old format. Remove the old prog options-based approach whenever possible and replace it with the use of call properties.
* all: introduce call propertiesAleksandr Nogikh2021-09-221-3/+8
| | | | | | | | | Call properties let us specify how each individual call within a program must be executed. So far the only way to enforce extra rules was to pass extra program-level properties (e.g. that is how fault injection was done). However, it entangles the logic and not flexible enough. Implement an ability to pass properties along with each individual call.
* executor: add missing includes to BSD's setup_faultAleksandr Nogikh2021-09-221-0/+1
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* executor/common_kvm_ppc64: fuzz more hypercallsAlexey Kardashevskiy2021-09-161-8/+8
| | | | | | | | | | | | | At the moment syzkaller only fuzzes the platform architecture defined hypercalls. However there are custom defined hypercalls which KVM handles, they make 2 groups - an extension of hypercalls and so-called ultracalls which are handled by the secure VM firmware but in absense of the secure VM facility, KVM gets to handle those as errors. This enables the two extra groups of hypercalls in KVM. If not enabled, KVM exits to let the userspace handle them (which syzkaller does not do). Signed-off-by: Alexey Kardashevskiy <aik@linux.ibm.com>
* executor/common_kvm_ppc64: enable nested KVMAlexey Kardashevskiy2021-09-161-0/+17
| | | | | | This is necessary to make KVM actually execute the instructions. Signed-off-by: Alexey Kardashevskiy <aik@linux.ibm.com>
* sys: skip kvm const extraction for non i386/amd64Aleksandr Nogikh2021-09-134-4/+4
| | | | | | | | | | | | It is impossible to compile a number of definitions in include/uapi/linux/kvm.h for other platforms, which leads to syz-extract failing to update constants. Skip processing of this file for all arches except i386 and amd64. This is a hacky and (hopefully) temporary solution until #2754 is implemented.
* executor: ifconfig destroy wants the interface (not device) name (#2739)Greg Steuck2021-09-021-1/+1
| | | | | | | | At least on OpenBSD this is the behavior: % doas ifconfig tun5 create % doas ifconfig tun5 destroy % doas ifconfig tun5 create % doas ifconfig /dev/tun5 destroy ifconfig: SIOCIFDESTROY: Invalid argument
* executor: fix remote coverage collectionAleksandr Nogikh2021-08-263-2/+4
| | | | | | | | | Currently the data_offset field of cover_t is only initialized for per-syscall coverage collection. As a result, remote coverage is read from an invalid location, fails to pass sanity checks and is not returned to syzkaller. Fix the initialization of cover_t fields.
* pkg/ifuzz/powerpc: add some RTAS fuzzingAlexey Kardashevskiy2021-07-191-0/+17
| | | | | | | | | | | | | | | RunTime Abstraction Services (RTAS) is an API used by the Linux powerpc/pseries platform to talk to the hypervisor. Under KVM, this is implemented as a custom hypercall (which we have support for) and an in memory array of parameters. The hypercall is H_RTAS and its only parameter is a pointer to the mentioned array. The vast majority of RTAS calls are handled normally by QEMU and only a handful by KVM. This adds fuzzing of 4 RTAS calls. This uses a chunk from main 256MB RAM for parameters. The parameters are big endian hence "<<24" for the token. To allow more targeted fuzzing, use iset.GenerateInt(). Signed-off-by: Alexey Kardashevskiy <aik@linux.ibm.com>
* executor/common_kvm_ppc64: run with enabled MMUAlexey Kardashevskiy2021-07-192-1/+147
| | | | | | | | | | | | | | | | | | | | | This sets up a page table to map the text in order to exercise more code paths in the KVM. This defines flags to control the MMU state. When enabled, this creates a simple page table at the 64K offset and maps all the RAM. The fuzzer code is placed right after the table. The flags are: IR - enables MMU for instruction fetches DR - enables MMU for data loads/stores PR - "problem state", i.e. userspace (implies DR and IR) PID1 - initializes a process table for PID>0 (PID#0 is used by the VM OS normally) This adds a simple "syz_kvm_setup_cpu_ppc64" syz-test with MSR=IR|DR|LE which is a typical Linux kernel mode. Signed-off-by: Alexey Kardashevskiy <aik@linux.ibm.com>
* executor/common_kvm_ppc64: fix KVM supportAlexey Kardashevskiy2021-07-196-12/+256
| | | | | | | | | | | | | | | | | | | | | | | | | | Turns out the ifuzz on powerpc did not ever properly work. This fixes syz_kvm_setup_cpu$ppc64: Enable the PAPR KVM capability (otherwise KVM_RUN fails right away). Finish generated sequences with the software debug breakpoint as there is no x86's "hlt" variant on POWER and otherwise KVM won't exit. Add exception handlers, use the software debug breakpoint instruction to trigger immediate exit from KVM with the only exception of the decrementer interrupt handler (timer) to recharge the timer and continue. Define and use endianness selection flag (Big vs. Little endian). Define the code generator similar to kvm_gen.cc which for now contains 2 simple tests and the decrementer interrupt handler code. Add test cases to the executor so "bin/linux_ppc64le/syz-executor test" can run some sensible tests. The tests copy 0xbadc0de around similar to x86 and uses gpr[3] is a return value register (similar to EAX). Signed-off-by: Alexey Kardashevskiy <aik@linux.ibm.com>
* executor: prepare for proper powerpc testingAlexey Kardashevskiy2021-07-191-5/+13
| | | | | | | | | | | | | | | This moves x86 instructions under GOARCH_amd64 and makes some cross-platforms changes. This allocates as much memory for a VM as syzkaller normally does so we are testing here what syzkaller itself runs. This should not cause any behavioral change for x86. Other arches are not properly supported anyway. Follow-up patches will use these changes for PPC64. Signed-off-by: Alexey Kardashevskiy <aik@linux.ibm.com>
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