/* * Platform-specific and custom entropy polling functions * * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later */ #if defined(__linux__) && !defined(_GNU_SOURCE) /* Ensure that syscall() is available even when compiling with -std=c99 */ #define _GNU_SOURCE #endif #include "common.h" #include #if defined(MBEDTLS_ENTROPY_C) #include "mbedtls/entropy.h" #include "mbedtls/entropy_poll.h" #include "mbedtls/error.h" #if defined(MBEDTLS_TIMING_C) #include "mbedtls/timing.h" #endif #if defined(MBEDTLS_HAVEGE_C) #include "mbedtls/havege.h" #endif #include "mbedtls/platform.h" #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY) #if !defined(unix) && !defined(__unix__) && !defined(__unix) && \ !defined(__APPLE__) && !defined(_WIN32) && !defined(__QNXNTO__) && \ !defined(__HAIKU__) && !defined(__midipix__) #error \ "Platform entropy sources only work on Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h" #endif #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) #if !defined(_WIN32_WINNT) #define _WIN32_WINNT 0x0400 #endif #include #include int mbedtls_platform_entropy_poll(void *data, unsigned char *output, size_t len, size_t *olen) { HCRYPTPROV provider; ((void) data); *olen = 0; if (CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT) == FALSE) { return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED; } if (CryptGenRandom(provider, (DWORD) len, output) == FALSE) { CryptReleaseContext(provider, 0); return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED; } CryptReleaseContext(provider, 0); *olen = len; return 0; } #else /* _WIN32 && !EFIX64 && !EFI32 */ /* * Test for Linux getrandom() support. * Since there is no wrapper in the libc yet, use the generic syscall wrapper * available in GNU libc and compatible libc's (eg uClibc). */ #if ((defined(__linux__) && defined(__GLIBC__)) || defined(__midipix__)) #include #include #if defined(SYS_getrandom) #define HAVE_GETRANDOM #include static int getrandom_wrapper(void *buf, size_t buflen, unsigned int flags) { /* MemSan cannot understand that the syscall writes to the buffer */ #if defined(__has_feature) #if __has_feature(memory_sanitizer) memset(buf, 0, buflen); #endif #endif return syscall(SYS_getrandom, buf, buflen, flags); } #endif /* SYS_getrandom */ #endif /* __linux__ || __midipix__ */ #if defined(__FreeBSD__) || defined(__DragonFly__) #include #if (defined(__FreeBSD__) && __FreeBSD_version >= 1200000) || \ (defined(__DragonFly__) && __DragonFly_version >= 500700) #include #include #define HAVE_GETRANDOM static int getrandom_wrapper(void *buf, size_t buflen, unsigned int flags) { return getrandom(buf, buflen, flags); } #endif /* (__FreeBSD__ && __FreeBSD_version >= 1200000) || (__DragonFly__ && __DragonFly_version >= 500700) */ #endif /* __FreeBSD__ || __DragonFly__ */ /* * Some BSD systems provide KERN_ARND. * This is equivalent to reading from /dev/urandom, only it doesn't require an * open file descriptor, and provides up to 256 bytes per call (basically the * same as getentropy(), but with a longer history). * * Documentation: https://netbsd.gw.com/cgi-bin/man-cgi?sysctl+7 */ #if (defined(__FreeBSD__) || defined(__NetBSD__)) && !defined(HAVE_GETRANDOM) #include #include #if defined(KERN_ARND) #define HAVE_SYSCTL_ARND static int sysctl_arnd_wrapper(unsigned char *buf, size_t buflen) { int name[2]; size_t len; name[0] = CTL_KERN; name[1] = KERN_ARND; while (buflen > 0) { len = buflen > 256 ? 256 : buflen; if (sysctl(name, 2, buf, &len, NULL, 0) == -1) { return -1; } buflen -= len; buf += len; } return 0; } #endif /* KERN_ARND */ #endif /* __FreeBSD__ || __NetBSD__ */ #include int mbedtls_platform_entropy_poll(void *data, unsigned char *output, size_t len, size_t *olen) { FILE *file; size_t read_len; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; ((void) data); #if defined(HAVE_GETRANDOM) ret = getrandom_wrapper(output, len, 0); if (ret >= 0) { *olen = ret; return 0; } else if (errno != ENOSYS) { return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED; } /* Fall through if the system call isn't known. */ #else ((void) ret); #endif /* HAVE_GETRANDOM */ #if defined(HAVE_SYSCTL_ARND) ((void) file); ((void) read_len); if (sysctl_arnd_wrapper(output, len) == -1) { return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED; } *olen = len; return 0; #else *olen = 0; file = fopen("/dev/urandom", "rb"); if (file == NULL) { return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED; } read_len = fread(output, 1, len, file); if (read_len != len) { fclose(file); return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED; } fclose(file); *olen = len; return 0; #endif /* HAVE_SYSCTL_ARND */ } #endif /* _WIN32 && !EFIX64 && !EFI32 */ #endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */ #if defined(MBEDTLS_TEST_NULL_ENTROPY) int mbedtls_null_entropy_poll(void *data, unsigned char *output, size_t len, size_t *olen) { ((void) data); ((void) output); *olen = 0; if (len < sizeof(unsigned char)) { return 0; } output[0] = 0; *olen = sizeof(unsigned char); return 0; } #endif #if defined(MBEDTLS_TIMING_C) int mbedtls_hardclock_poll(void *data, unsigned char *output, size_t len, size_t *olen) { unsigned long timer = mbedtls_timing_hardclock(); ((void) data); *olen = 0; if (len < sizeof(unsigned long)) { return 0; } memcpy(output, &timer, sizeof(unsigned long)); *olen = sizeof(unsigned long); return 0; } #endif /* MBEDTLS_TIMING_C */ #if defined(MBEDTLS_HAVEGE_C) int mbedtls_havege_poll(void *data, unsigned char *output, size_t len, size_t *olen) { mbedtls_havege_state *hs = (mbedtls_havege_state *) data; *olen = 0; if (mbedtls_havege_random(hs, output, len) != 0) { return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED; } *olen = len; return 0; } #endif /* MBEDTLS_HAVEGE_C */ #if defined(MBEDTLS_ENTROPY_NV_SEED) int mbedtls_nv_seed_poll(void *data, unsigned char *output, size_t len, size_t *olen) { unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE]; size_t use_len = MBEDTLS_ENTROPY_BLOCK_SIZE; ((void) data); memset(buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE); if (mbedtls_nv_seed_read(buf, MBEDTLS_ENTROPY_BLOCK_SIZE) < 0) { return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED; } if (len < use_len) { use_len = len; } memcpy(output, buf, use_len); *olen = use_len; return 0; } #endif /* MBEDTLS_ENTROPY_NV_SEED */ #endif /* MBEDTLS_ENTROPY_C */