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Lock random seed file

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This commit is contained in:
Werner Koch 2006-02-09 12:54:41 +00:00
parent af67c98ee9
commit 2410941461
7 changed files with 106 additions and 2 deletions
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87
cipher/random.c
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@ -1,6 +1,6 @@
/* random.c - random number generator
* Copyright (C) 1998, 1999, 2000, 2001, 2002,
* 2003 Free Software Foundation, Inc.
* 2003, 2006 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
@ -70,6 +70,14 @@
#endif
/* Check whether we can lock the seed file read write. */
#if defined(HAVE_FCNTL) && defined(HAVE_FTRUNCATE) && !defined(HAVE_W32_SYSTEM)
#define LOCK_SEED_FILE 1
#else
#define LOCK_SEED_FILE 0
#endif
#if SIZEOF_UNSIGNED_LONG == 8
#define ADD_VALUE 0xa5a5a5a5a5a5a5a5
#elif SIZEOF_UNSIGNED_LONG == 4
@ -105,6 +113,7 @@ static int just_mixed;
static int did_initial_extra_seeding;
static char *seed_file_name;
static int allow_seed_file_update;
static int no_seed_file_locking;
static int secure_alloc;
static int quick_test;
@ -272,6 +281,13 @@ random_is_faked()
return faked_rng || quick_test;
}
/* Disable locking of seed files. */
void
random_disable_locking ()
{
no_seed_file_locking = 1;
}
/****************
* Return a pointer to a randomized buffer of level 0 and LENGTH bits
* caller must free the buffer.
@ -359,6 +375,50 @@ set_random_seed_file( const char *name )
seed_file_name = xstrdup( name );
}
/* Lock an open file identified by file descriptor FD and wait a
reasonable time to succeed. With FOR_WRITE set to true a Rite lock
will be taken. FNAME is used only for diagnostics. Returns 0 on
success or -1 on error. */
#if LOCK_SEED_FILE
static int
lock_seed_file (int fd, const char *fname, int for_write)
{
struct flock lck;
struct timeval tv;
int backoff=0;
if (no_seed_file_locking)
return 0;
/* We take a lock on the entire file. */
memset (&lck, 0, sizeof lck);
lck.l_type = for_write? F_WRLCK : F_RDLCK;
lck.l_whence = SEEK_SET;
while (fcntl (fd, F_SETLK, &lck) == -1)
{
if (errno != EAGAIN && errno != EACCES)
{
log_info (_("can't lock `%s': %s\n"), fname, strerror (errno));
return -1;
}
if (backoff > 2) /* Show the first message after ~2.25 seconds. */
log_info( _("waiting for lock on `%s'...\n"), fname);
tv.tv_sec = backoff;
tv.tv_usec = 250000;
select (0, NULL, NULL, NULL, &tv);
if (backoff < 10)
backoff++ ;
}
return 0;
}
#endif /*LOCK_SEED_FILE*/
/****************
* Read in a seed form the random_seed file
* and return true if this was successful
@ -388,6 +448,12 @@ read_seed_file(void)
log_info(_("can't open `%s': %s\n"), seed_file_name, strerror(errno) );
return 0;
}
if (lock_seed_file (fd, seed_file_name, 0))
{
close (fd);
return 0;
}
if( fstat( fd, &sb ) ) {
log_info(_("can't stat `%s': %s\n"), seed_file_name, strerror(errno) );
close(fd);
@ -468,12 +534,31 @@ update_random_seed_file()
fd = open( seed_file_name, O_WRONLY|O_CREAT|O_TRUNC|O_BINARY,
S_IRUSR|S_IWUSR );
#else
# if LOCK_SEED_FILE
fd = open( seed_file_name, O_WRONLY|O_CREAT, S_IRUSR|S_IWUSR );
# else
fd = open( seed_file_name, O_WRONLY|O_CREAT|O_TRUNC, S_IRUSR|S_IWUSR );
# endif
#endif
if( fd == -1 ) {
log_info(_("can't create `%s': %s\n"), seed_file_name, strerror(errno) );
return;
}
if (lock_seed_file (fd, seed_file_name, 1))
{
close (fd);
return;
}
#if LOCK_SEED_FILE
if (ftruncate (fd, 0))
{
log_info(_("can't write `%s': %s\n"), seed_file_name, strerror(errno));
close (fd);
return;
}
#endif /*LOCK_SEED_FILE*/
do {
i = write( fd, keypool, POOLSIZE );
} while( i == -1 && errno == EINTR );