diff --git a/MAINTAINERS b/MAINTAINERS index 969329f83e68b3f12fd04d0c62a5a40d3eef30ea..195dd58cac1da0b74d7badde2ed4245c8a2ec030 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -2184,6 +2184,14 @@ F: qtest.c F: accel/qtest.c F: tests/qtest/ +Device Fuzzing +M: Alexander Bulekov +R: Paolo Bonzini +R: Bandan Das +R: Stefan Hajnoczi +S: Maintained +F: tests/qtest/fuzz/ + Register API M: Alistair Francis S: Maintained diff --git a/tests/qtest/fuzz/Makefile.include b/tests/qtest/fuzz/Makefile.include new file mode 100644 index 0000000000000000000000000000000000000000..8632bb89f46ac28f8521cbc91c59733755336121 --- /dev/null +++ b/tests/qtest/fuzz/Makefile.include @@ -0,0 +1,6 @@ +QEMU_PROG_FUZZ=qemu-fuzz-$(TARGET_NAME)$(EXESUF) + +fuzz-obj-y += tests/qtest/libqtest.o +fuzz-obj-y += tests/qtest/fuzz/fuzz.o # Fuzzer skeleton + +FUZZ_CFLAGS += -I$(SRC_PATH)/tests -I$(SRC_PATH)/tests/qtest diff --git a/tests/qtest/fuzz/fuzz.c b/tests/qtest/fuzz/fuzz.c new file mode 100644 index 0000000000000000000000000000000000000000..0d78ac8d364cd28fb5572e35bfbfe00aaea7b190 --- /dev/null +++ b/tests/qtest/fuzz/fuzz.c @@ -0,0 +1,179 @@ +/* + * fuzzing driver + * + * Copyright Red Hat Inc., 2019 + * + * Authors: + * Alexander Bulekov + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + * + */ + +#include "qemu/osdep.h" + +#include + +#include "sysemu/qtest.h" +#include "sysemu/runstate.h" +#include "sysemu/sysemu.h" +#include "qemu/main-loop.h" +#include "tests/qtest/libqtest.h" +#include "tests/qtest/libqos/qgraph.h" +#include "fuzz.h" + +#define MAX_EVENT_LOOPS 10 + +typedef struct FuzzTargetState { + FuzzTarget *target; + QSLIST_ENTRY(FuzzTargetState) target_list; +} FuzzTargetState; + +typedef QSLIST_HEAD(, FuzzTargetState) FuzzTargetList; + +static const char *fuzz_arch = TARGET_NAME; + +static FuzzTargetList *fuzz_target_list; +static FuzzTarget *fuzz_target; +static QTestState *fuzz_qts; + + + +void flush_events(QTestState *s) +{ + int i = MAX_EVENT_LOOPS; + while (g_main_context_pending(NULL) && i-- > 0) { + main_loop_wait(false); + } +} + +static QTestState *qtest_setup(void) +{ + qtest_server_set_send_handler(&qtest_client_inproc_recv, &fuzz_qts); + return qtest_inproc_init(&fuzz_qts, false, fuzz_arch, + &qtest_server_inproc_recv); +} + +void fuzz_add_target(const FuzzTarget *target) +{ + FuzzTargetState *tmp; + FuzzTargetState *target_state; + if (!fuzz_target_list) { + fuzz_target_list = g_new0(FuzzTargetList, 1); + } + + QSLIST_FOREACH(tmp, fuzz_target_list, target_list) { + if (g_strcmp0(tmp->target->name, target->name) == 0) { + fprintf(stderr, "Error: Fuzz target name %s already in use\n", + target->name); + abort(); + } + } + target_state = g_new0(FuzzTargetState, 1); + target_state->target = g_new0(FuzzTarget, 1); + *(target_state->target) = *target; + QSLIST_INSERT_HEAD(fuzz_target_list, target_state, target_list); +} + + + +static void usage(char *path) +{ + printf("Usage: %s --fuzz-target=FUZZ_TARGET [LIBFUZZER ARGUMENTS]\n", path); + printf("where FUZZ_TARGET is one of:\n"); + FuzzTargetState *tmp; + if (!fuzz_target_list) { + fprintf(stderr, "Fuzz target list not initialized\n"); + abort(); + } + QSLIST_FOREACH(tmp, fuzz_target_list, target_list) { + printf(" * %s : %s\n", tmp->target->name, + tmp->target->description); + } + exit(0); +} + +static FuzzTarget *fuzz_get_target(char* name) +{ + FuzzTargetState *tmp; + if (!fuzz_target_list) { + fprintf(stderr, "Fuzz target list not initialized\n"); + abort(); + } + + QSLIST_FOREACH(tmp, fuzz_target_list, target_list) { + if (strcmp(tmp->target->name, name) == 0) { + return tmp->target; + } + } + return NULL; +} + + +/* Executed for each fuzzing-input */ +int LLVMFuzzerTestOneInput(const unsigned char *Data, size_t Size) +{ + /* + * Do the pre-fuzz-initialization before the first fuzzing iteration, + * instead of before the actual fuzz loop. This is needed since libfuzzer + * may fork off additional workers, prior to the fuzzing loop, and if + * pre_fuzz() sets up e.g. shared memory, this should be done for the + * individual worker processes + */ + static int pre_fuzz_done; + if (!pre_fuzz_done && fuzz_target->pre_fuzz) { + fuzz_target->pre_fuzz(fuzz_qts); + pre_fuzz_done = true; + } + + fuzz_target->fuzz(fuzz_qts, Data, Size); + return 0; +} + +/* Executed once, prior to fuzzing */ +int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp) +{ + + char *target_name; + + /* Initialize qgraph and modules */ + qos_graph_init(); + module_call_init(MODULE_INIT_FUZZ_TARGET); + module_call_init(MODULE_INIT_QOM); + module_call_init(MODULE_INIT_LIBQOS); + + if (*argc <= 1) { + usage(**argv); + } + + /* Identify the fuzz target */ + target_name = (*argv)[1]; + if (!strstr(target_name, "--fuzz-target=")) { + usage(**argv); + } + + target_name += strlen("--fuzz-target="); + + fuzz_target = fuzz_get_target(target_name); + if (!fuzz_target) { + usage(**argv); + } + + fuzz_qts = qtest_setup(); + + if (fuzz_target->pre_vm_init) { + fuzz_target->pre_vm_init(); + } + + /* Run QEMU's softmmu main with the fuzz-target dependent arguments */ + const char *init_cmdline = fuzz_target->get_init_cmdline(fuzz_target); + + /* Split the runcmd into an argv and argc */ + wordexp_t result; + wordexp(init_cmdline, &result, 0); + + qemu_init(result.we_wordc, result.we_wordv, NULL); + + return 0; +} diff --git a/tests/qtest/fuzz/fuzz.h b/tests/qtest/fuzz/fuzz.h new file mode 100644 index 0000000000000000000000000000000000000000..03901d414e128b5303191091279cf29fb9de19d4 --- /dev/null +++ b/tests/qtest/fuzz/fuzz.h @@ -0,0 +1,95 @@ +/* + * fuzzing driver + * + * Copyright Red Hat Inc., 2019 + * + * Authors: + * Alexander Bulekov + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + * + */ + +#ifndef FUZZER_H_ +#define FUZZER_H_ + +#include "qemu/osdep.h" +#include "qemu/units.h" +#include "qapi/error.h" + +#include "tests/qtest/libqtest.h" + +/** + * A libfuzzer fuzzing target + * + * The QEMU fuzzing binary is built with all available targets, each + * with a unique @name that can be specified on the command-line to + * select which target should run. + * + * A target must implement ->fuzz() to process a random input. If QEMU + * crashes in ->fuzz() then libfuzzer will record a failure. + * + * Fuzzing targets are registered with fuzz_add_target(): + * + * static const FuzzTarget fuzz_target = { + * .name = "my-device-fifo", + * .description = "Fuzz the FIFO buffer registers of my-device", + * ... + * }; + * + * static void register_fuzz_target(void) + * { + * fuzz_add_target(&fuzz_target); + * } + * fuzz_target_init(register_fuzz_target); + */ +typedef struct FuzzTarget { + const char *name; /* target identifier (passed to --fuzz-target=)*/ + const char *description; /* help text */ + + + /* + * returns the arg-list that is passed to qemu/softmmu init() + * Cannot be NULL + */ + const char* (*get_init_cmdline)(struct FuzzTarget *); + + /* + * will run once, prior to running qemu/softmmu init. + * eg: set up shared-memory for communication with the child-process + * Can be NULL + */ + void(*pre_vm_init)(void); + + /* + * will run once, after QEMU has been initialized, prior to the fuzz-loop. + * eg: detect the memory map + * Can be NULL + */ + void(*pre_fuzz)(QTestState *); + + /* + * accepts and executes an input from libfuzzer. this is repeatedly + * executed during the fuzzing loop. Its should handle setup, input + * execution and cleanup. + * Cannot be NULL + */ + void(*fuzz)(QTestState *, const unsigned char *, size_t); + +} FuzzTarget; + +void flush_events(QTestState *); +void reboot(QTestState *); + +/* + * makes a copy of *target and adds it to the target-list. + * i.e. fine to set up target on the caller's stack + */ +void fuzz_add_target(const FuzzTarget *target); + +int LLVMFuzzerTestOneInput(const unsigned char *Data, size_t Size); +int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp); + +#endif +