Make UtilRandomString() more secure.
Two ways this is more secure: 1. The seed is only generated once, not every time the function is called. 2. All threads share the same seed, which means timing attacks aren't possible. Because we are using a mutex, performance may suffer slightly.
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1 changed files with 13 additions and 4 deletions
17
src/Util.c
17
src/Util.c
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@ -32,6 +32,7 @@
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#include <math.h>
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#include <time.h>
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#include <unistd.h>
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#include <errno.h>
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#include <sys/time.h>
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#include <sys/stat.h>
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@ -399,14 +400,13 @@ UtilGetLine(char **linePtr, size_t * n, FILE * stream)
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char *
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UtilRandomString(size_t len)
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{
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static const char charset[] =
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"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
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static const char charset[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
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static pthread_mutex_t seedLock = PTHREAD_MUTEX_INITIALIZER;
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static unsigned int seed = 0;
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char *str;
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size_t i;
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unsigned int seed = UtilServerTs() * (unsigned long) pthread_self();
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if (!len)
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{
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return NULL;
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@ -418,11 +418,20 @@ UtilRandomString(size_t len)
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return NULL;
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}
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pthread_mutex_lock(&seedLock);
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if (!seed)
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{
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seed = UtilServerTs() ^ getpid() ^ (unsigned long) pthread_self();
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}
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for (i = 0; i < len; i++)
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{
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str[i] = charset[rand_r(&seed) % (sizeof(charset) - 1)];
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}
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pthread_mutex_unlock(&seedLock);
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str[len] = '\0';
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return str;
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}
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