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authorCorinna Vinschen <corinna@vinschen.de>2000-07-24 11:33:02 +0000
committerCorinna Vinschen <corinna@vinschen.de>2000-07-24 11:33:02 +0000
commit9602ffc30b29e48544c3d947367e118ad8c61c92 (patch)
treeab560b540b885e1e9f161989af2573b29744afc4
parent5b7d5241feab3447025fc09c0f76bcd8dc80ba62 (diff)
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* fhandler.h (class fhandler_dev_random): Add members for managing
pseudo randomness. * fhandler_random.cc: Rearrange. Use pseudo random number generator as entropy source if system entropy isn't available and if device is used as /dev/urandom. Allow initializing device by calling write().
-rw-r--r--winsup/cygwin/ChangeLog8
-rw-r--r--winsup/cygwin/fhandler.h5
-rw-r--r--winsup/cygwin/fhandler_random.cc93
3 files changed, 95 insertions, 11 deletions
diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 556a61a..37e60c3 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,11 @@
+Mon Jul 24 13:26:00 2000 Corinna Vinschen <corinna@vinschen.de>
+
+ * fhandler.h (class fhandler_dev_random): Add members for managing
+ pseudo randomness.
+ * fhandler_random.cc: Rearrange. Use pseudo random number generator
+ as entropy source if system entropy isn't available and if device is
+ used as /dev/urandom. Allow initializing device by calling write().
+
Sun Jul 23 23:11:00 2000 Corinna Vinschen <corinna@vinschen.de>
* fhandler.h: Add comment.
diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index 9ff028a..ba6319b 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -743,6 +743,11 @@ class fhandler_dev_random: public fhandler_base
protected:
int unit;
HCRYPTPROV crypt_prov;
+ long pseudo;
+
+ BOOL crypt_gen_random (void *ptr, size_t len);
+ int pseudo_write (const void *ptr, size_t len);
+ int pseudo_read (void *ptr, size_t len);
public:
fhandler_dev_random (const char *name, int unit);
diff --git a/winsup/cygwin/fhandler_random.cc b/winsup/cygwin/fhandler_random.cc
index 9b784a8..9991c3b 100644
--- a/winsup/cygwin/fhandler_random.cc
+++ b/winsup/cygwin/fhandler_random.cc
@@ -1,4 +1,4 @@
-/* fhandler_dev_random.cc: code to access /dev/random
+/* fhandler_dev_random.cc: code to access /dev/random and /dev/urandom
Copyright 2000 Cygnus Solutions.
@@ -11,11 +11,15 @@ Cygwin license. Please consult the file "CYGWIN_LICENSE" for
details. */
#include <errno.h>
+#include <limits.h>
#include "winsup.h"
#define RANDOM 8
#define URANDOM 9
+#define PSEUDO_MULTIPLIER (6364136223846793005LL)
+#define PSEUDO_SHIFTVAL (21)
+
fhandler_dev_random::fhandler_dev_random (const char *name, int nunit)
: fhandler_base (FH_RANDOM, name),
unit(nunit),
@@ -31,35 +35,102 @@ fhandler_dev_random::open (const char *, int flags, mode_t)
return 1;
}
+BOOL
+fhandler_dev_random::crypt_gen_random (void *ptr, size_t len)
+{
+ if (!crypt_prov
+ && !CryptAcquireContext (&crypt_prov, NULL, MS_DEF_PROV, PROV_RSA_FULL,
+ CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET)
+ && !CryptAcquireContext (&crypt_prov, NULL, MS_DEF_PROV, PROV_RSA_FULL,
+ CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET
+ | CRYPT_NEWKEYSET))
+ {
+ debug_printf ("%E = CryptAquireContext()");
+ return FALSE;
+ }
+ if (!CryptGenRandom (crypt_prov, len, (BYTE *)ptr))
+ {
+ debug_printf ("%E = CryptGenRandom()");
+ return FALSE;
+ }
+ return TRUE;
+}
+
int
-fhandler_dev_random::write (const void *, size_t len)
+fhandler_dev_random::pseudo_write (const void *ptr, size_t len)
{
+ /* Use buffer to mess up the pseudo random number generator. */
+ for (size_t i = 0; i < len; ++i)
+ pseudo = (pseudo + ((unsigned char *)ptr)[i]) * PSEUDO_MULTIPLIER + 1;
return len;
}
int
-fhandler_dev_random::read (void *ptr, size_t len)
+fhandler_dev_random::write (const void *ptr, size_t len)
{
if (!len)
return 0;
- if (!crypt_prov
- && !CryptAcquireContext (&crypt_prov, NULL, MS_DEF_PROV, PROV_RSA_FULL,
- CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET)
- && !CryptAcquireContext (&crypt_prov, NULL, MS_DEF_PROV, PROV_RSA_FULL,
- CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET
- | CRYPT_NEWKEYSET ))
+ if (!ptr)
{
- __seterrno ();
+ set_errno (EINVAL);
return -1;
}
- if (!CryptGenRandom (crypt_prov, len, (BYTE *)ptr))
+
+ /* Limit len to a value <= 512 since we don't want to overact.
+ Copy to local buffer because CryptGenRandom violates const. */
+ unsigned char buf[512];
+ size_t limited_len = len <= 512 ? len : 512;
+ memcpy (buf, ptr, limited_len);
+
+ /* Mess up system entropy source. Return error if device is /dev/random. */
+ if (!crypt_gen_random (buf, limited_len) && unit == RANDOM)
{
__seterrno ();
return -1;
}
+ /* Mess up the pseudo random number generator. */
+ pseudo_write (buf, limited_len);
return len;
}
+int
+fhandler_dev_random::pseudo_read (void *ptr, size_t len)
+{
+ /* Use pseudo random number generator as fallback entropy source.
+ This multiplier was obtained from Knuth, D.E., "The Art of
+ Computer Programming," Vol 2, Seminumerical Algorithms, Third
+ Edition, Addison-Wesley, 1998, p. 106 (line 26) & p. 108 */
+ for (size_t i = 0; i < len; ++i)
+ {
+ pseudo = pseudo * PSEUDO_MULTIPLIER + 1;
+ ((unsigned char *)ptr)[i] = (pseudo >> PSEUDO_SHIFTVAL) & UCHAR_MAX;
+ }
+ return len;
+}
+
+int
+fhandler_dev_random::read (void *ptr, size_t len)
+{
+ if (!len)
+ return 0;
+ if (!ptr)
+ {
+ set_errno (EINVAL);
+ return -1;
+ }
+
+ if (crypt_gen_random (ptr, len))
+ return len;
+ /* If device is /dev/urandom, use pseudo number generator as fallback.
+ Don't do this for /dev/random since it's intended for uses that need
+ very high quality randomness. */
+ if (unit == URANDOM)
+ return pseudo_read (ptr, len);
+
+ __seterrno ();
+ return -1;
+}
+
off_t
fhandler_dev_random::lseek (off_t, int)
{