diff options
Diffstat (limited to 'libs/libsodium/src/randombytes/sysrandom/randombytes_sysrandom.c')
| -rw-r--r-- | libs/libsodium/src/randombytes/sysrandom/randombytes_sysrandom.c | 382 |
1 files changed, 382 insertions, 0 deletions
diff --git a/libs/libsodium/src/randombytes/sysrandom/randombytes_sysrandom.c b/libs/libsodium/src/randombytes/sysrandom/randombytes_sysrandom.c new file mode 100644 index 0000000000..f4dec08f5b --- /dev/null +++ b/libs/libsodium/src/randombytes/sysrandom/randombytes_sysrandom.c @@ -0,0 +1,382 @@ + +#include <assert.h> +#include <errno.h> +#include <fcntl.h> +#include <limits.h> +#include <stdint.h> +#include <string.h> +#ifndef _WIN32 +# include <unistd.h> +#endif + +#include <stdlib.h> +#include <sys/types.h> +#ifndef _WIN32 +# include <sys/stat.h> +# include <sys/time.h> +#endif +#ifdef __linux__ +# ifdef __dietlibc__ +# define _LINUX_SOURCE +# else +# include <sys/syscall.h> +# endif +# include <poll.h> +#endif + +#include "core.h" +#include "private/common.h" +#include "randombytes.h" +#include "randombytes_sysrandom.h" +#include "utils.h" + +#ifdef _WIN32 +/* `RtlGenRandom` is used over `CryptGenRandom` on Microsoft Windows based systems: + * - `CryptGenRandom` requires pulling in `CryptoAPI` which causes unnecessary + * memory overhead if this API is not being used for other purposes + * - `RtlGenRandom` is thus called directly instead. A detailed explanation + * can be found here: https://blogs.msdn.microsoft.com/michael_howard/2005/01/14/cryptographically-secure-random-number-on-windows-without-using-cryptoapi/ + * + * In spite of the disclaimer on the `RtlGenRandom` documentation page that was + * written back in the Windows XP days, this function is here to stay. The CRT + * function `rand_s()` directly depends on it, so touching it would break many + * applications released since Windows XP. + * + * Also note that Rust, Firefox and BoringSSL (thus, Google Chrome and everything + * based on Chromium) also depend on it, and that libsodium allows the RNG to be + * replaced without patching nor recompiling the library. + */ +# include <windows.h> +# define RtlGenRandom SystemFunction036 +# if defined(__cplusplus) +extern "C" +# endif +BOOLEAN NTAPI RtlGenRandom(PVOID RandomBuffer, ULONG RandomBufferLength); +# pragma comment(lib, "advapi32.lib") +#endif + +#if defined(__OpenBSD__) || defined(__CloudABI__) +# define HAVE_SAFE_ARC4RANDOM 1 +#endif + +#ifndef SSIZE_MAX +# define SSIZE_MAX (SIZE_MAX / 2 - 1) +#endif + +#ifdef HAVE_SAFE_ARC4RANDOM + +static uint32_t +randombytes_sysrandom(void) +{ + return arc4random(); +} + +static void +randombytes_sysrandom_stir(void) +{ +} + +static void +randombytes_sysrandom_buf(void * const buf, const size_t size) +{ + arc4random_buf(buf, size); +} + +static int +randombytes_sysrandom_close(void) +{ + return 0; +} + +#else /* __OpenBSD__ */ + +typedef struct SysRandom_ { + int random_data_source_fd; + int initialized; + int getrandom_available; +} SysRandom; + +static SysRandom stream = { + SODIUM_C99(.random_data_source_fd =) -1, + SODIUM_C99(.initialized =) 0, + SODIUM_C99(.getrandom_available =) 0 +}; + +#ifndef _WIN32 +static ssize_t +safe_read(const int fd, void * const buf_, size_t size) +{ + unsigned char *buf = (unsigned char *) buf_; + ssize_t readnb; + + assert(size > (size_t) 0U); + assert(size <= SSIZE_MAX); + do { + while ((readnb = read(fd, buf, size)) < (ssize_t) 0 && + (errno == EINTR || errno == EAGAIN)); /* LCOV_EXCL_LINE */ + if (readnb < (ssize_t) 0) { + return readnb; /* LCOV_EXCL_LINE */ + } + if (readnb == (ssize_t) 0) { + break; /* LCOV_EXCL_LINE */ + } + size -= (size_t) readnb; + buf += readnb; + } while (size > (ssize_t) 0); + + return (ssize_t) (buf - (unsigned char *) buf_); +} +#endif + +#ifndef _WIN32 +# if defined(__linux__) && !defined(USE_BLOCKING_RANDOM) && !defined(NO_BLOCKING_RANDOM_POLL) +static int +randombytes_block_on_dev_random(void) +{ + struct pollfd pfd; + int fd; + int pret; + + fd = open("/dev/random", O_RDONLY); + if (fd == -1) { + return 0; + } + pfd.fd = fd; + pfd.events = POLLIN; + pfd.revents = 0; + do { + pret = poll(&pfd, 1, -1); + } while (pret < 0 && (errno == EINTR || errno == EAGAIN)); + if (pret != 1) { + (void) close(fd); + errno = EIO; + return -1; + } + return close(fd); +} +# endif + +static int +randombytes_sysrandom_random_dev_open(void) +{ +/* LCOV_EXCL_START */ + struct stat st; + static const char *devices[] = { +# ifndef USE_BLOCKING_RANDOM + "/dev/urandom", +# endif + "/dev/random", NULL + }; + const char **device = devices; + int fd; + +# if defined(__linux__) && !defined(USE_BLOCKING_RANDOM) && !defined(NO_BLOCKING_RANDOM_POLL) + if (randombytes_block_on_dev_random() != 0) { + return -1; + } +# endif + do { + fd = open(*device, O_RDONLY); + if (fd != -1) { + if (fstat(fd, &st) == 0 && +# ifdef __COMPCERT__ + 1 +# elif defined(S_ISNAM) + (S_ISNAM(st.st_mode) || S_ISCHR(st.st_mode)) +# else + S_ISCHR(st.st_mode) +# endif + ) { +# if defined(F_SETFD) && defined(FD_CLOEXEC) + (void) fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC); +# endif + return fd; + } + (void) close(fd); + } else if (errno == EINTR) { + continue; + } + device++; + } while (*device != NULL); + + errno = EIO; + return -1; +/* LCOV_EXCL_STOP */ +} + +# if defined(__dietlibc__) || (defined(SYS_getrandom) && defined(__NR_getrandom)) +static int +_randombytes_linux_getrandom(void * const buf, const size_t size) +{ + int readnb; + + assert(size <= 256U); + do { +# ifdef __dietlibc__ + readnb = getrandom(buf, size, 0); +# else + readnb = syscall(SYS_getrandom, buf, (int) size, 0); +# endif + } while (readnb < 0 && (errno == EINTR || errno == EAGAIN)); + + return (readnb == (int) size) - 1; +} + +static int +randombytes_linux_getrandom(void * const buf_, size_t size) +{ + unsigned char *buf = (unsigned char *) buf_; + size_t chunk_size = 256U; + + do { + if (size < chunk_size) { + chunk_size = size; + assert(chunk_size > (size_t) 0U); + } + if (_randombytes_linux_getrandom(buf, chunk_size) != 0) { + return -1; + } + size -= chunk_size; + buf += chunk_size; + } while (size > (size_t) 0U); + + return 0; +} +# endif + +static void +randombytes_sysrandom_init(void) +{ + const int errno_save = errno; + +# if defined(SYS_getrandom) && defined(__NR_getrandom) + { + unsigned char fodder[16]; + + if (randombytes_linux_getrandom(fodder, sizeof fodder) == 0) { + stream.getrandom_available = 1; + errno = errno_save; + return; + } + stream.getrandom_available = 0; + } +# endif + + if ((stream.random_data_source_fd = + randombytes_sysrandom_random_dev_open()) == -1) { + sodium_misuse(); /* LCOV_EXCL_LINE */ + } + errno = errno_save; +} + +#else /* _WIN32 */ + +static void +randombytes_sysrandom_init(void) +{ +} +#endif + +static void +randombytes_sysrandom_stir(void) +{ + if (stream.initialized == 0) { + randombytes_sysrandom_init(); + stream.initialized = 1; + } +} + +static void +randombytes_sysrandom_stir_if_needed(void) +{ + if (stream.initialized == 0) { + randombytes_sysrandom_stir(); + } +} + +static int +randombytes_sysrandom_close(void) +{ + int ret = -1; + +#ifndef _WIN32 + if (stream.random_data_source_fd != -1 && + close(stream.random_data_source_fd) == 0) { + stream.random_data_source_fd = -1; + stream.initialized = 0; + ret = 0; + } +# if defined(SYS_getrandom) && defined(__NR_getrandom) + if (stream.getrandom_available != 0) { + ret = 0; + } +# endif +#else /* _WIN32 */ + if (stream.initialized != 0) { + stream.initialized = 0; + ret = 0; + } +#endif + return ret; +} + +static void +randombytes_sysrandom_buf(void * const buf, const size_t size) +{ + randombytes_sysrandom_stir_if_needed(); +#if defined(ULONG_LONG_MAX) && defined(SIZE_MAX) +# if SIZE_MAX > ULONG_LONG_MAX + /* coverity[result_independent_of_operands] */ + assert(size <= ULONG_LONG_MAX); +# endif +#endif +#ifndef _WIN32 +# if defined(SYS_getrandom) && defined(__NR_getrandom) + if (stream.getrandom_available != 0) { + if (randombytes_linux_getrandom(buf, size) != 0) { + sodium_misuse(); /* LCOV_EXCL_LINE */ + } + return; + } +# endif + if (stream.random_data_source_fd == -1 || + safe_read(stream.random_data_source_fd, buf, size) != (ssize_t) size) { + sodium_misuse(); /* LCOV_EXCL_LINE */ + } +#else + COMPILER_ASSERT(randombytes_BYTES_MAX <= 0xffffffffUL); + if (size > (size_t) 0xffffffffUL) { + sodium_misuse(); /* LCOV_EXCL_LINE */ + } + if (! RtlGenRandom((PVOID) buf, (ULONG) size)) { + sodium_misuse(); /* LCOV_EXCL_LINE */ + } +#endif +} + +static uint32_t +randombytes_sysrandom(void) +{ + uint32_t r; + + randombytes_sysrandom_buf(&r, sizeof r); + + return r; +} + +#endif /* __OpenBSD__ */ + +static const char * +randombytes_sysrandom_implementation_name(void) +{ + return "sysrandom"; +} + +struct randombytes_implementation randombytes_sysrandom_implementation = { + SODIUM_C99(.implementation_name =) randombytes_sysrandom_implementation_name, + SODIUM_C99(.random =) randombytes_sysrandom, + SODIUM_C99(.stir =) randombytes_sysrandom_stir, + SODIUM_C99(.uniform =) NULL, + SODIUM_C99(.buf =) randombytes_sysrandom_buf, + SODIUM_C99(.close =) randombytes_sysrandom_close +}; |