diff --git a/libselinux/fuzz/input b/libselinux/fuzz/input new file mode 100644 index 000000000..e69de29bb diff --git a/libselinux/fuzz/selabel_file_compiled-fuzzer.c b/libselinux/fuzz/selabel_file_compiled-fuzzer.c new file mode 100644 index 000000000..cf0710ad1 --- /dev/null +++ b/libselinux/fuzz/selabel_file_compiled-fuzzer.c @@ -0,0 +1,281 @@ +#include +#include +#include +#include +#include + +#include + +#include "../src/label_file.h" + +extern int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size); + +#define MEMFD_FILE_NAME "file_contexts" +#define CTRL_PARTIAL (1U << 0) +#define CTRL_FIND_ALL (1U << 1) +#define CTRL_MODE (1U << 2) + + +__attribute__ ((format(printf, 2, 3))) +static int null_log(int type __attribute__((unused)), const char *fmt __attribute__((unused)), ...) +{ + return 0; +} + +static int validate_context(char **ctxp) +{ + assert(strcmp(*ctxp, "<>") != 0); + + if (*ctxp[0] == '\0') { + errno = EINVAL; + return -1; + } + + return 0; +} + +static int write_full(int fd, const void *data, size_t size) +{ + ssize_t rc; + const unsigned char *p = data; + + while (size > 0) { + rc = write(fd, p, size); + if (rc == -1) { + if (errno == EINTR) + continue; + + return -1; + } + + p += rc; + size -= rc; + } + + return 0; +} + +static FILE* convert_data(const uint8_t *data, size_t size) +{ + FILE* stream; + int fd, rc; + + fd = memfd_create(MEMFD_FILE_NAME, MFD_CLOEXEC); + if (fd == -1) + return NULL; + + rc = write_full(fd, data, size); + if (rc == -1) { + close(fd); + return NULL; + } + + stream = fdopen(fd, "r"); + if (!stream) { + close(fd); + return NULL; + } + + rc = fseek(stream, 0L, SEEK_SET); + if (rc == -1) { + fclose(stream); + return NULL; + } + + return stream; +} + +int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) +{ + struct selabel_handle rec; + struct saved_data sdata = {}; + struct spec_node *root = NULL; + FILE* fp = NULL; + struct lookup_result *result = NULL; + uint8_t control; + uint8_t *fcontext_data1 = NULL, *fcontext_data2 = NULL, *fcontext_data3 = NULL; + char *key = NULL; + size_t fcontext_data1_len, fcontext_data2_len, fcontext_data3_len, key_len; + bool partial, find_all; + mode_t mode; + int rc; + + /* + * Treat first byte as control byte, whether to use partial mode, find all matches or mode to lookup + */ + if (size == 0) + return 0; + + control = data[0]; + data++; + size--; + + if (control & ~(CTRL_PARTIAL | CTRL_FIND_ALL | CTRL_MODE)) + return 0; + + partial = control & CTRL_PARTIAL; + find_all = control & CTRL_FIND_ALL; + /* S_IFSOCK has the highest integer value */ + mode = (control & CTRL_MODE) ? S_IFSOCK : 0; + + + /* + * Split the fuzzer input into up to four pieces: one to three compiled fcontext + * definitions (to mimic file_contexts, file_contexts.homedirs and file_contexts.local, + * and the lookup key + */ + const unsigned char separator[4] = { 0xde, 0xad, 0xbe, 0xef }; + const uint8_t *sep = memmem(data, size, separator, 4); + if (!sep || sep == data) + return 0; + + fcontext_data1_len = sep - data; + fcontext_data1 = malloc(fcontext_data1_len); + if (!fcontext_data1) + goto cleanup; + + memcpy(fcontext_data1, data, fcontext_data1_len); + data += fcontext_data1_len + 4; + size -= fcontext_data1_len + 4; + + sep = memmem(data, size, separator, 4); + if (sep) { + fcontext_data2_len = sep - data; + fcontext_data2 = malloc(fcontext_data2_len); + if (!fcontext_data2) + goto cleanup; + + memcpy(fcontext_data2, data, fcontext_data2_len); + data += fcontext_data2_len + 4; + size -= fcontext_data2_len + 4; + } + + sep = memmem(data, size, separator, 4); + if (sep) { + fcontext_data3_len = sep - data; + fcontext_data3 = malloc(fcontext_data3_len); + if (!fcontext_data3) + goto cleanup; + + memcpy(fcontext_data3, data, fcontext_data3_len); + data += fcontext_data3_len + 4; + size -= fcontext_data3_len + 4; + } + + key_len = size; + key = malloc(key_len + 1); + if (!key) + goto cleanup; + + memcpy(key, data, key_len); + key[key_len] = '\0'; + + + /* + * Mock selabel handle + */ + rec = (struct selabel_handle) { + .backend = SELABEL_CTX_FILE, + .validating = 1, + .data = &sdata, + }; + + selinux_set_callback(SELINUX_CB_LOG, (union selinux_callback) { .func_log = &null_log }); + /* validate to pre-compile regular expressions */ + selinux_set_callback(SELINUX_CB_VALIDATE, (union selinux_callback) { .func_validate = &validate_context }); + + root = calloc(1, sizeof(*root)); + if (!root) + goto cleanup; + + sdata.root = root; + + fp = convert_data(fcontext_data1, fcontext_data1_len); + if (!fp) + goto cleanup; + + errno = 0; + rc = load_mmap(fp, fcontext_data1_len, &rec, MEMFD_FILE_NAME); + if (rc) { + assert(errno != 0); + goto cleanup; + } + + fclose(fp); + + fp = convert_data(fcontext_data2, fcontext_data2_len); + if (!fp) + goto cleanup; + + errno = 0; + rc = load_mmap(fp, fcontext_data2_len, &rec, MEMFD_FILE_NAME); + if (rc) { + assert(errno != 0); + goto cleanup; + } + + fclose(fp); + + fp = convert_data(fcontext_data3, fcontext_data3_len); + if (!fp) + goto cleanup; + + errno = 0; + rc = load_mmap(fp, fcontext_data3_len, &rec, MEMFD_FILE_NAME); + if (rc) { + assert(errno != 0); + goto cleanup; + } + + sort_specs(&sdata); + + assert(cmp(&rec, &rec) == SELABEL_EQUAL); + + errno = 0; + result = lookup_all(&rec, key, mode, partial, find_all); + + if (!result) + assert(errno != 0); + + for (const struct lookup_result *res = result; res; res = res->next) { + assert(res->regex_str); + assert(res->regex_str[0] != '\0'); + assert(res->lr->ctx_raw); + assert(res->lr->ctx_raw[0] != '\0'); + assert(strcmp(res->lr->ctx_raw, "<>") != 0); + assert(!res->lr->ctx_trans); + assert(res->lr->validated); + assert(res->prefix_len <= strlen(res->regex_str)); + } + + +cleanup: + free_lookup_result(result); + if (fp) + fclose(fp); + if (sdata.root) { + free_spec_node(sdata.root); + free(sdata.root); + } + + { + struct mmap_area *area, *last_area; + + area = sdata.mmap_areas; + while (area) { + rc = munmap(area->addr, area->len); + assert(rc == 0); + last_area = area; + area = area->next; + free(last_area); + } + } + + free(key); + free(fcontext_data3); + free(fcontext_data2); + free(fcontext_data1); + + /* Non-zero return values are reserved for future use. */ + return 0; +} diff --git a/libselinux/fuzz/selabel_file_text-fuzzer.c b/libselinux/fuzz/selabel_file_text-fuzzer.c new file mode 100644 index 000000000..5d851de14 --- /dev/null +++ b/libselinux/fuzz/selabel_file_text-fuzzer.c @@ -0,0 +1,225 @@ +#include +#include +#include +#include +#include + +#include + +#include "../src/label_file.h" + +extern int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size); + +#define MEMFD_FILE_NAME "file_contexts" +#define CTRL_PARTIAL (1U << 0) +#define CTRL_FIND_ALL (1U << 1) +#define CTRL_MODE (1U << 2) + + +__attribute__ ((format(printf, 2, 3))) +static int null_log(int type __attribute__((unused)), const char *fmt __attribute__((unused)), ...) +{ + return 0; +} + +static int validate_context(char **ctxp) +{ + assert(strcmp(*ctxp, "<>") != 0); + + if (*ctxp[0] == '\0') { + errno = EINVAL; + return -1; + } + + return 0; +} + +static int write_full(int fd, const void *data, size_t size) +{ + ssize_t rc; + const unsigned char *p = data; + + while (size > 0) { + rc = write(fd, p, size); + if (rc == -1) { + if (errno == EINTR) + continue; + + return -1; + } + + p += rc; + size -= rc; + } + + return 0; +} + +static FILE* convert_data(const uint8_t *data, size_t size) +{ + FILE* stream; + int fd, rc; + + fd = memfd_create(MEMFD_FILE_NAME, MFD_CLOEXEC); + if (fd == -1) + return NULL; + + rc = write_full(fd, data, size); + if (rc == -1) { + close(fd); + return NULL; + } + + stream = fdopen(fd, "r"); + if (!stream) { + close(fd); + return NULL; + } + + rc = fseek(stream, 0L, SEEK_SET); + if (rc == -1) { + fclose(stream); + return NULL; + } + + return stream; +} + +int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) +{ + struct selabel_handle rec; + struct saved_data sdata = {}; + struct spec_node *root = NULL; + FILE* fp = NULL; + struct lookup_result *result = NULL; + uint8_t control; + uint8_t *fcontext_data = NULL; + char *key = NULL; + size_t fcontext_data_len, key_len; + bool partial, find_all; + mode_t mode; + int rc; + + /* + * Treat first byte as control byte, whether to use partial mode, find all matches or mode to lookup + */ + if (size == 0) + return 0; + + control = data[0]; + data++; + size--; + + if (control & ~(CTRL_PARTIAL | CTRL_FIND_ALL | CTRL_MODE)) + return 0; + + partial = control & CTRL_PARTIAL; + find_all = control & CTRL_FIND_ALL; + /* S_IFSOCK has the highest integer value */ + mode = (control & CTRL_MODE) ? S_IFSOCK : 0; + + + /* + * Split the fuzzer input into two pieces: the textual fcontext definition and the lookup key + */ + const unsigned char separator[4] = { 0xde, 0xad, 0xbe, 0xef }; + const uint8_t *sep = memmem(data, size, separator, 4); + if (!sep || sep == data) + return 0; + + fcontext_data_len = sep - data; + fcontext_data = malloc(fcontext_data_len); + if (!fcontext_data) + goto cleanup; + + memcpy(fcontext_data, data, fcontext_data_len); + + key_len = size - fcontext_data_len - 4; + key = malloc(key_len + 1); + if (!key) + goto cleanup; + + memcpy(key, sep + 4, key_len); + key[key_len] = '\0'; + + + /* + * Mock selabel handle + */ + rec = (struct selabel_handle) { + .backend = SELABEL_CTX_FILE, + .validating = 1, + .data = &sdata, + }; + + selinux_set_callback(SELINUX_CB_LOG, (union selinux_callback) { .func_log = &null_log }); + /* validate to pre-compile regular expressions */ + selinux_set_callback(SELINUX_CB_VALIDATE, (union selinux_callback) { .func_validate = &validate_context }); + + root = calloc(1, sizeof(*root)); + if (!root) + goto cleanup; + + sdata.root = root; + + fp = convert_data(fcontext_data, fcontext_data_len); + if (!fp) + goto cleanup; + + errno = 0; + rc = process_text_file(fp, /*prefix=*/ NULL, &rec, MEMFD_FILE_NAME); + if (rc) { + assert(errno != 0); + goto cleanup; + } + + sort_specs(&sdata); + + assert(cmp(&rec, &rec) == SELABEL_EQUAL); + + errno = 0; + result = lookup_all(&rec, key, mode, partial, find_all); + + if (!result) + assert(errno != 0); + + for (const struct lookup_result *res = result; res; res = res->next) { + assert(res->regex_str); + assert(res->regex_str[0] != '\0'); + assert(res->lr->ctx_raw); + assert(res->lr->ctx_raw[0] != '\0'); + assert(strcmp(res->lr->ctx_raw, "<>") != 0); + assert(!res->lr->ctx_trans); + assert(res->lr->validated); + assert(res->prefix_len <= strlen(res->regex_str)); + } + + +cleanup: + free_lookup_result(result); + if (fp) + fclose(fp); + if (sdata.root) { + free_spec_node(sdata.root); + free(sdata.root); + } + + { + struct mmap_area *area, *last_area; + + area = sdata.mmap_areas; + while (area) { + rc = munmap(area->addr, area->len); + assert(rc == 0); + last_area = area; + area = area->next; + free(last_area); + } + } + + free(key); + free(fcontext_data); + + /* Non-zero return values are reserved for future use. */ + return 0; +} diff --git a/libselinux/src/label_file.c b/libselinux/src/label_file.c index c7713d7c1..267f708ef 100644 --- a/libselinux/src/label_file.c +++ b/libselinux/src/label_file.c @@ -27,6 +27,13 @@ #include "label_file.h" +#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION +# define FUZZ_EXTERN +#else +# define FUZZ_EXTERN static +#endif /* FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION */ + + /* * Warn about duplicate specifications. */ @@ -114,8 +121,8 @@ static int nodups_spec_node(const struct spec_node *node, const char *path) return rc; } -static int process_text_file(FILE *fp, const char *prefix, - struct selabel_handle *rec, const char *path) +FUZZ_EXTERN int process_text_file(FILE *fp, const char *prefix, + struct selabel_handle *rec, const char *path) { int rc; size_t line_len; @@ -720,8 +727,8 @@ static int load_mmap_spec_node(struct mmap_area *mmap_area, const char *path, bo return 0; } -static int load_mmap(FILE *fp, const size_t len, struct selabel_handle *rec, - const char *path) +FUZZ_EXTERN int load_mmap(FILE *fp, const size_t len, struct selabel_handle *rec, + const char *path) { struct saved_data *data = rec->data; struct spec_node *root = NULL; @@ -1449,16 +1456,7 @@ static uint32_t search_literal_spec(const struct literal_spec *array, uint32_t s return (uint32_t)-1; } -struct lookup_result { - const char *regex_str; - struct selabel_lookup_rec *lr; - uint16_t prefix_len; - uint8_t file_kind; - bool has_meta_chars; - struct lookup_result *next; -}; - -static void free_lookup_result(struct lookup_result *result) +FUZZ_EXTERN void free_lookup_result(struct lookup_result *result) { struct lookup_result *tmp; @@ -1690,11 +1688,11 @@ static uint8_t mode_to_file_kind(int type) { // Finds all the matches of |key| in the given context. Returns the result in // the allocated array and updates the match count. If match_count is NULL, // stops early once the 1st match is found. -static struct lookup_result *lookup_all(struct selabel_handle *rec, - const char *key, - int type, - bool partial, - bool find_all) +FUZZ_EXTERN struct lookup_result *lookup_all(struct selabel_handle *rec, + const char *key, + int type, + bool partial, + bool find_all) { struct saved_data *data = (struct saved_data *)rec->data; struct lookup_result *result = NULL; @@ -2283,7 +2281,7 @@ static enum selabel_cmp_result spec_node_cmp(const struct spec_node *node1, cons return result; } -static enum selabel_cmp_result cmp(const struct selabel_handle *h1, const struct selabel_handle *h2) +FUZZ_EXTERN enum selabel_cmp_result cmp(const struct selabel_handle *h1, const struct selabel_handle *h2) { const struct saved_data *data1, *data2; diff --git a/libselinux/src/label_file.h b/libselinux/src/label_file.h index 2dc772eb9..529a1bd26 100644 --- a/libselinux/src/label_file.h +++ b/libselinux/src/label_file.h @@ -50,6 +50,23 @@ #define LABEL_FILE_KIND_LNK 6 #define LABEL_FILE_KIND_REG 7 +/* Only exported for fuzzing */ +struct lookup_result { + const char *regex_str; + struct selabel_lookup_rec *lr; + uint16_t prefix_len; + uint8_t file_kind; + bool has_meta_chars; + struct lookup_result *next; +}; +#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION +extern int load_mmap(FILE *fp, const size_t len, struct selabel_handle *rec, const char *path); +extern int process_text_file(FILE *fp, const char *prefix, struct selabel_handle *rec, const char *path); +extern void free_lookup_result(struct lookup_result *result); +extern struct lookup_result *lookup_all(struct selabel_handle *rec, const char *key, int type, bool partial, bool find_all); +extern enum selabel_cmp_result cmp(const struct selabel_handle *h1, const struct selabel_handle *h2); +#endif /* FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION */ + struct selabel_sub { char *src; unsigned int slen; diff --git a/scripts/oss-fuzz.sh b/scripts/oss-fuzz.sh index 069f130ae..9376b6e42 100755 --- a/scripts/oss-fuzz.sh +++ b/scripts/oss-fuzz.sh @@ -44,10 +44,13 @@ export LIB_FUZZING_ENGINE=${LIB_FUZZING_ENGINE:--fsanitize=fuzzer} rm -rf "$DESTDIR" make -C libsepol clean +make -C libselinux clean # LIBSO and LIBMAP shouldn't be expanded here because their values are unknown until Makefile # has been read by make # shellcheck disable=SC2016 make -C libsepol V=1 LD_SONAME_FLAGS='-soname,$(LIBSO),--version-script=$(LIBMAP)' -j"$(nproc)" install +# shellcheck disable=SC2016 +make -C libselinux V=1 LD_SONAME_FLAGS='-soname,$(LIBSO),--version-script=libselinux.map' -j"$(nproc)" install ## secilc fuzzer ## @@ -84,3 +87,25 @@ $CXX $CXXFLAGS $LIB_FUZZING_ENGINE checkpolicy-fuzzer.o checkpolicy/*.o "$DESTDI zip -j "$OUT/checkpolicy-fuzzer_seed_corpus.zip" checkpolicy/fuzz/min_pol.mls.conf cp checkpolicy/fuzz/checkpolicy-fuzzer.dict "$OUT/" + +## selabel-file text fcontext based fuzzer ## + +# CFLAGS, CXXFLAGS and LIB_FUZZING_ENGINE have to be split to be accepted by +# the compiler/linker so they shouldn't be quoted +# shellcheck disable=SC2086 +$CC $CFLAGS -DUSE_PCRE2 -DPCRE2_CODE_UNIT_WIDTH=8 -c -o selabel_file_text-fuzzer.o libselinux/fuzz/selabel_file_text-fuzzer.c +# shellcheck disable=SC2086 +$CXX $CXXFLAGS $LIB_FUZZING_ENGINE selabel_file_text-fuzzer.o "$DESTDIR/usr/lib/libselinux.a" -lpcre2-8 -o "$OUT/selabel_file_text-fuzzer" + +zip -j "$OUT/selabel_file_text-fuzzer_seed_corpus.zip" libselinux/fuzz/input + +## selabel-file compiled fcontext based fuzzer ## + +# CFLAGS, CXXFLAGS and LIB_FUZZING_ENGINE have to be split to be accepted by +# the compiler/linker so they shouldn't be quoted +# shellcheck disable=SC2086 +$CC $CFLAGS -DUSE_PCRE2 -DPCRE2_CODE_UNIT_WIDTH=8 -c -o selabel_file_compiled-fuzzer.o libselinux/fuzz/selabel_file_compiled-fuzzer.c +# shellcheck disable=SC2086 +$CXX $CXXFLAGS $LIB_FUZZING_ENGINE selabel_file_compiled-fuzzer.o "$DESTDIR/usr/lib/libselinux.a" -lpcre2-8 -o "$OUT/selabel_file_compiled-fuzzer" + +zip -j "$OUT/selabel_file_compiled-fuzzer_seed_corpus.zip" libselinux/fuzz/input