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Remove multi-thread support from arc4random.

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Sudo is not multi-threaded so we don't need the added complexity.
This commit is contained in:
Todd C. Miller
2020-01-28 06:41:42 -07:00
parent aa7ea419f0
commit 13cc65038f
4 changed files with 48 additions and 171 deletions
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101
lib/util/arc4random.c
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@@ -60,32 +60,26 @@
#define minimum(a, b) ((a) < (b) ? (a) : (b))
#if defined(__GNUC__) || defined(_MSC_VER)
#define inline __inline
#else /* __GNUC__ || _MSC_VER */
#define inline
#endif /* !__GNUC__ && !_MSC_VER */
#ifdef __GNUC__
# define inline __inline
#else /* !__GNUC__ */
# define inline
#endif /* !__GNUC__ */
/* Sudo isn't multithreaded */
#define _ARC4_LOCK()
#define _ARC4_UNLOCK()
#define KEYSZ 32
#define IVSZ 8
#define BLOCKSZ 64
#define RSBUFSZ (16*BLOCKSZ)
/* Marked MAP_INHERIT_ZERO, so zero'd out in fork children. */
static struct _rs {
size_t rs_have; /* valid bytes at end of rs_buf */
size_t rs_count; /* bytes till reseed */
} *rs;
/* Maybe be preserved in fork children, if _rs_allocate() decides. */
static struct _rsx {
chacha_ctx rs_chacha; /* chacha context for random keystream */
unsigned char rs_buf[RSBUFSZ]; /* keystream blocks */
} *rsx;
static inline int _rs_allocate(struct _rs **, struct _rsx **);
static inline void _rs_forkdetect(void);
#include "arc4random.h"
static int rs_initialized;
static pid_t rs_stir_pid;
static chacha_ctx rs; /* chacha context for random keystream */
static u_char rs_buf[RSBUFSZ]; /* keystream blocks */
static size_t rs_have; /* valid bytes at end of rs_buf */
static size_t rs_count; /* bytes till reseed */
static inline void _rs_rekey(unsigned char *dat, size_t datlen);
@@ -94,14 +88,8 @@ _rs_init(unsigned char *buf, size_t n)
{
if (n < KEYSZ + IVSZ)
return;
if (rs == NULL) {
if (_rs_allocate(&rs, &rsx) == -1)
abort();
}
chacha_keysetup(&rsx->rs_chacha, buf, KEYSZ * 8, 0);
chacha_ivsetup(&rsx->rs_chacha, buf + KEYSZ);
chacha_keysetup(&rs, buf, KEYSZ * 8, 0);
chacha_ivsetup(&rs, buf + KEYSZ);
}
static void
@@ -110,54 +98,54 @@ _rs_stir(void)
unsigned char rnd[KEYSZ + IVSZ];
if (getentropy(rnd, sizeof rnd) == -1)
_getentropy_fail();
raise(SIGKILL);
if (!rs)
if (!rs_initialized) {
rs_initialized = 1;
_rs_init(rnd, sizeof(rnd));
else
} else
_rs_rekey(rnd, sizeof(rnd));
memset_s(rnd, sizeof(rnd), 0, sizeof(rnd)); /* discard source seed */
/* invalidate rs_buf */
rs->rs_have = 0;
memset(rsx->rs_buf, 0, sizeof(rsx->rs_buf));
rs_have = 0;
memset(rs_buf, 0, sizeof(rs_buf));
rs->rs_count = 1600000;
rs_count = 1600000;
}
static inline void
_rs_stir_if_needed(size_t len)
{
_rs_forkdetect();
if (!rs || rs->rs_count <= len)
pid_t pid = getpid();
if (rs_count <= len || !rs_initialized || rs_stir_pid != pid) {
rs_stir_pid = pid;
_rs_stir();
if (rs->rs_count <= len)
rs->rs_count = 0;
else
rs->rs_count -= len;
} else
rs_count -= len;
}
static inline void
_rs_rekey(unsigned char *dat, size_t datlen)
{
#ifndef KEYSTREAM_ONLY
memset(rsx->rs_buf, 0, sizeof(rsx->rs_buf));
memset(rs_buf, 0, sizeof(rs_buf));
#endif
/* fill rs_buf with the keystream */
chacha_encrypt_bytes(&rsx->rs_chacha, rsx->rs_buf,
rsx->rs_buf, sizeof(rsx->rs_buf));
chacha_encrypt_bytes(&rs, rs_buf, rs_buf, sizeof(rs_buf));
/* mix in optional user provided data */
if (dat) {
size_t i, m;
m = minimum(datlen, KEYSZ + IVSZ);
for (i = 0; i < m; i++)
rsx->rs_buf[i] ^= dat[i];
rs_buf[i] ^= dat[i];
}
/* immediately reinit for backtracking resistance */
_rs_init(rsx->rs_buf, KEYSZ + IVSZ);
memset(rsx->rs_buf, 0, KEYSZ + IVSZ);
rs->rs_have = sizeof(rsx->rs_buf) - KEYSZ - IVSZ;
_rs_init(rs_buf, KEYSZ + IVSZ);
memset(rs_buf, 0, KEYSZ + IVSZ);
rs_have = sizeof(rs_buf) - KEYSZ - IVSZ;
}
#ifdef notdef
@@ -170,17 +158,16 @@ _rs_random_buf(void *_buf, size_t n)
_rs_stir_if_needed(n);
while (n > 0) {
if (rs->rs_have > 0) {
m = minimum(n, rs->rs_have);
keystream = rsx->rs_buf + sizeof(rsx->rs_buf)
- rs->rs_have;
if (rs_have > 0) {
m = minimum(n, rs_have);
keystream = rs_buf + sizeof(rs_buf) - rs_have;
memcpy(buf, keystream, m);
memset(keystream, 0, m);
buf += m;
n -= m;
rs->rs_have -= m;
rs_have -= m;
}
if (rs->rs_have == 0)
if (rs_have == 0)
_rs_rekey(NULL, 0);
}
}
@@ -192,12 +179,12 @@ _rs_random_u32(uint32_t *val)
unsigned char *keystream;
_rs_stir_if_needed(sizeof(*val));
if (rs->rs_have < sizeof(*val))
if (rs_have < sizeof(*val))
_rs_rekey(NULL, 0);
keystream = rsx->rs_buf + sizeof(rsx->rs_buf) - rs->rs_have;
keystream = rs_buf + sizeof(rs_buf) - rs_have;
memcpy(val, keystream, sizeof(*val));
memset(keystream, 0, sizeof(*val));
rs->rs_have -= sizeof(*val);
rs_have -= sizeof(*val);
}
uint32_t