Use of the rand/srand API is error prone and trips up static analyzers. Just drop it and expect users to use random32() instead, which is always seeded and outputs 32-bit integers directly instead of 16-bit.
Signed-off-by: Ahmad Fatoum <a.fat...@pengutronix.de> --- Documentation/user/random.rst | 8 ++++---- commands/2048.c | 4 ++-- commands/nandtest.c | 11 +++++------ commands/seed.c | 2 +- common/boot.c | 2 +- common/ubiformat.c | 4 +--- drivers/net/phy/dp83tg720.c | 2 +- include/net.h | 3 +-- include/stdlib.h | 22 +++++----------------- lib/random.c | 29 +++++++---------------------- 10 files changed, 28 insertions(+), 59 deletions(-) diff --git a/Documentation/user/random.rst b/Documentation/user/random.rst index 95dad72e55a7..dc3c32ffeb95 100644 --- a/Documentation/user/random.rst +++ b/Documentation/user/random.rst @@ -11,8 +11,8 @@ Barebox provides two types of RNG sources - PRNG and HWRNG: (which may include truly random values). Although sequences that are closer to truly random can be generated using hardware random number generators." Pseudorandom number generator. https://en.wikipedia.org/wiki/Pseudorandom_number_generator (2017.05.08). - The PRNG used by Barebox is LCG (linear congruential generator) non cryptographically - secure, so please use with caution. + The PRNG used by Barebox is a Xorshift* and is not seeded in a manner appropriate + for cryptographic operations, so please use with caution. - The HWRNG framework is software that makes use of a special hardware feature on your CPU, SoC or motherboard. It can‘t provide any guarantee about cryptographic @@ -23,8 +23,8 @@ API .. code-block:: c - /* seed the PRNG. */ - void srand(unsigned int seed); + /* mix extra entropy into the PRNG state. */ + void srand_xor(u64 seed); /* Fill the buffer with PRNG bits. */ void get_random_bytes(void *buf, int len); diff --git a/commands/2048.c b/commands/2048.c index 3ad9c0f3ae37..c8b35bdb7d0a 100644 --- a/commands/2048.c +++ b/commands/2048.c @@ -233,10 +233,10 @@ static void addRandom(uint16_t board[SIZE][SIZE]) } if (len>0) { - r = rand()%len; + r = random32()%len; x = list[r][0]; y = list[r][1]; - n = ((rand()%10)/9+1)*2; + n = ((random32()%10)/9+1)*2; board[x][y]=n; } } diff --git a/commands/nandtest.c b/commands/nandtest.c index bc138646a460..fa64d9ccea0b 100644 --- a/commands/nandtest.c +++ b/commands/nandtest.c @@ -25,7 +25,8 @@ static struct region_info_user memregion; static struct mtd_info_user meminfo; static struct mtd_ecc_stats oldstats, newstats; -static int fd, seed; +static int fd; +static u64 seed; /* Markbad option flag */ static int markbad; @@ -184,7 +185,7 @@ static int erase_and_write(loff_t ofs, unsigned char *data, * debugging information. */ ret = memcmp(data, rbuf, meminfo.erasesize); if (ret < 0) { - printf("\ncompare failed. seed %d\n", seed); + printf("\ncompare failed. seed %llu\n", seed); for (i = 0; i < meminfo.erasesize; i++) { if (data[i] != rbuf[i]) printf("Block 0x%llx byte 0x%0x (page 0x%x offset 0x%x) is %02x should be %02x\n", @@ -236,7 +237,7 @@ static int do_nandtest(int argc, char *argv[]) markbad = 1; break; case 's': - seed = simple_strtoul(optarg, NULL, 0); + seed = simple_strtoull(optarg, NULL, 0); break; case 'i': nr_iterations = simple_strtoul(optarg, NULL, 0); @@ -352,8 +353,6 @@ static int do_nandtest(int argc, char *argv[]) test_ofs < flash_end; test_ofs += meminfo.erasesize) { pb_update(test_ofs); - srand(seed); - seed = rand(); if (ioctl(fd, MEMGETBADBLOCK, &test_ofs)) { printf("\nBad block at 0x%08llx\n", @@ -364,7 +363,7 @@ static int do_nandtest(int argc, char *argv[]) if (do_nandtest_ro) { ret = read_corrected(test_ofs, rbuf, length); } else { - get_random_bytes(wbuf, meminfo.erasesize); + randbuf_r(&seed, wbuf, meminfo.erasesize); ret = erase_and_write(test_ofs, wbuf, rbuf, length); } diff --git a/commands/seed.c b/commands/seed.c index 3947208834ff..3495fab1fd27 100644 --- a/commands/seed.c +++ b/commands/seed.c @@ -12,7 +12,7 @@ static int do_seed(int argc, char *argv[]) return COMMAND_ERROR_USAGE; if (isdigit(*argv[1])) { - srand(simple_strtoul(argv[1], NULL, 0)); + srand_xor(simple_strtoull(argv[1], NULL, 0)); return 0; } diff --git a/common/boot.c b/common/boot.c index 6aa2b1394961..e1844c470888 100644 --- a/common/boot.c +++ b/common/boot.c @@ -360,7 +360,7 @@ static char *parse_nfs_url(const char *url) mountpath = xstrdup(prevpath); } else { mountpath = basprintf("/mnt/nfs-%s-bootentries-%08x", host, - rand()); + random32()); if (port) options = basprintf("mountport=%s,port=%s", port, port); diff --git a/common/ubiformat.c b/common/ubiformat.c index d8399ad9d6a0..c9256983b501 100644 --- a/common/ubiformat.c +++ b/common/ubiformat.c @@ -488,10 +488,8 @@ int ubiformat(struct mtd_info *mtd, struct ubiformat_args *args) if (!args->ubi_ver) args->ubi_ver = 1; - if (!args->image_seq) { - srand(get_time_ns()); + if (!args->image_seq) args->image_seq = random32(); - } if (!is_power_of_2(mtd->writesize)) { errmsg("min. I/O size is %d, but should be power of 2", diff --git a/drivers/net/phy/dp83tg720.c b/drivers/net/phy/dp83tg720.c index a9e5560adc85..0e02f714fea7 100644 --- a/drivers/net/phy/dp83tg720.c +++ b/drivers/net/phy/dp83tg720.c @@ -81,7 +81,7 @@ static int dp83tg720_phy_init(struct phy_device *phydev) * the link partner. The polling interval is set to 150ms +/- 50ms. */ phydev->polling_interval = (DP83TG720S_POLL_TIMEOUT_MS + - (rand() % 10) * 10) * MSECOND; + prandom_u32_max(100)) * MSECOND; /* According to the "DP83TG720R-Q1 1000BASE-T1 Automotive Ethernet PHY * datasheet (Rev. C)" - "T6.2 Post reset stabilization-time prior to diff --git a/include/net.h b/include/net.h index 52f6a0fa97ad..439e0a4c9b61 100644 --- a/include/net.h +++ b/include/net.h @@ -423,8 +423,7 @@ int generate_ether_addr(u8 *addr, int ethid); */ static inline void random_ether_addr(u8 *addr) { - srand(get_time_ns()); - get_random_bytes(addr, ETH_ALEN); + get_noncrypto_bytes(addr, ETH_ALEN); addr[0] &= 0xfe; /* clear multicast bit */ addr[0] |= 0x02; /* set local assignment bit (IEEE802) */ } diff --git a/include/stdlib.h b/include/stdlib.h index 12a81cfc31a3..36613eb34a99 100644 --- a/include/stdlib.h +++ b/include/stdlib.h @@ -6,20 +6,13 @@ #include <types.h> #include <malloc.h> -#define RAND_MAX 32767 - -/* return a pseudo-random integer in the range [0, RAND_MAX] */ -unsigned int rand(void); - -/* set the seed for rand () */ -void srand(unsigned int seed); - struct hwrng; /* fill a buffer with pseudo-random data */ #if IN_PROPER void randbuf_r(u64 *x, void *buf, size_t len); void srand_xor(u64 entropy); +u32 random32(void); void get_noncrypto_bytes(void *buf, size_t len); void get_random_bytes(void *buf, int len); int get_crypto_bytes(void *buf, int len); @@ -33,6 +26,10 @@ static inline void srand_xor(u64 entropy) { BUG(); } +static inline u32 random32(void) +{ + BUG(); +} static inline void get_noncrypto_bytes(void *buf, size_t len) { BUG(); @@ -51,15 +48,6 @@ static inline int hwrng_get_crypto_bytes(struct hwrng *rng, void *buf, int len) } #endif -static inline u32 random32(void) -{ - u32 ret; - - get_random_bytes(&ret, 4); - - return ret; -} - static inline u32 prandom_u32_max(u32 ep_ro) { return (u32)(((u64) random32() * ep_ro) >> 32); diff --git a/lib/random.c b/lib/random.c index 51c68dcd427b..36fb1ec08f05 100644 --- a/lib/random.c +++ b/lib/random.c @@ -15,23 +15,6 @@ #include <stdlib.h> #include <linux/hw_random.h> -static unsigned int random_seed; - -#if RAND_MAX > 32767 -#error this rand implementation is for RAND_MAX < 32678 only. -#endif - -unsigned int rand(void) -{ - random_seed = random_seed * 1103515245 + 12345; - return (random_seed / 65536) % (RAND_MAX + 1); -} - -void srand(unsigned int seed) -{ - random_seed = seed; -} - static u64 prng_state = 1; /** @@ -113,17 +96,19 @@ void get_noncrypto_bytes(void *buf, size_t len) randbuf_r(&prng_state, buf, len); } +u32 random32(void) +{ + return rand_r(&prng_state); +} + /** * get_random_bytes - get pseudo random numbers. * This interface can be good enough to generate MAC address * or use for NAND test. */ -void get_random_bytes(void *_buf, int len) +void get_random_bytes(void *buf, int len) { - char *buf = _buf; - - while (len--) - *buf++ = rand() % 256; + get_noncrypto_bytes(buf, len); } int hwrng_get_crypto_bytes(struct hwrng *rng, void *buf, int len) -- 2.39.5
