Check if a random "file" is really a device file, and treat it

specially if it is.
Add a few OpenBSD-specific cases.
This is part of a large change submitted by Markus Friedl <markus@openbsd.org>

diff --git a/crypto/rand/rand_unix.c b/crypto/rand/rand_unix.c
index 8b4c483312967a3ec6f476ac2f8f344d75c17335..ef80201212883d84cce9dd64c1f08935ca50802c 100644 (file)
--- a/crypto/rand/rand_unix.c
+++ b/crypto/rand/rand_unix.c
@@ -125,6 +125,24 @@
 #include <unistd.h>
 #include <time.h>
 
+#ifdef __OpenBSD__
+int RAND_poll(void)
+{
+       u_int32_t rnd = 0, i;
+       unsigned char buf[ENTROPY_NEEDED];
+
+       for (i = 0; i < sizeof(buf); i++) {
+               if (i % 4 == 0)
+                       rnd = arc4random();
+               buf[i] = rnd;
+               rnd >>= 8;
+       }
+       RAND_add(buf, sizeof(buf), ENTROPY_NEEDED);
+       memset(buf, 0, sizeof(buf));
+
+       return 1;
+}
+#else
 int RAND_poll(void)
 {
        unsigned long l;
@@ -236,6 +254,7 @@ int RAND_poll(void)
 #endif
 }
 
+#endif
 #endif
 
 #if defined(OPENSSL_SYS_VXWORKS)

diff --git a/crypto/rand/randfile.c b/crypto/rand/randfile.c
index 41574768ab762a32c6ec32d1f3a55c0e0968745f..f1f250c5bfbacf62aa82468590da5cb614aa3b57 100644 (file)
--- a/crypto/rand/randfile.c
+++ b/crypto/rand/randfile.c
@@ -56,6 +56,9 @@
  * [including the GNU Public Licence.]
  */
 
+/* We need to define this to get macros like S_IFBLK and S_IFCHR */
+#define _XOPEN_SOURCE 1
+
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -64,6 +67,7 @@
 #include "e_os.h"
 #include <openssl/crypto.h>
 #include <openssl/rand.h>
+#include <openssl/buffer.h>
 
 #ifdef OPENSSL_SYS_VMS
 #include <unixio.h>
@@ -106,6 +110,14 @@ int RAND_load_file(const char *file, long bytes)
 
        in=fopen(file,"rb");
        if (in == NULL) goto err;
+       if (sb.st_mode & (S_IFBLK | S_IFCHR)) {
+         /* this file is a device. we don't want read an infinite number
+          * of bytes from a random device, nor do we want to use buffered
+          * I/O because we will waste system entropy. 
+          */
+         bytes = (bytes == -1) ? 2048 : bytes; /* ok, is 2048 enough? */
+         setvbuf(in, NULL, _IONBF, 0); /* don't do buffered reads */
+       }
        for (;;)
                {
                if (bytes > 0)
@@ -135,7 +147,20 @@ int RAND_write_file(const char *file)
        int i,ret=0,rand_err=0;
        FILE *out = NULL;
        int n;
+       struct stat sb;
        
+       i=stat(file,&sb);
+       if (i != -1) { 
+         if (sb.st_mode & (S_IFBLK | S_IFCHR)) {
+           /* this file is a device. we don't write back to it. 
+            * we "succeed" on the assumption this is some sort 
+            * of random device. Otherwise attempting to write to 
+            * and chmod the device causes problems.
+            */
+           return(1); 
+         }
+       }
+
 #if defined(O_CREAT) && !defined(OPENSSL_SYS_WIN32)
        /* For some reason Win32 can't write to files created this way */
        
@@ -197,16 +222,17 @@ err:
 const char *RAND_file_name(char *buf, size_t size)
        {
        char *s=NULL;
-       char *ret=NULL;
+       int ok = 0;
+#ifdef __OpenBSD__
+       struct stat sb;
+#endif
 
        if (OPENSSL_issetugid() == 0)
                s=getenv("RANDFILE");
-       if (s != NULL)
+       if (s != NULL && *s && strlen(s) + 1 < size)
                {
-               if(strlen(s) >= size)
+               if (BUF_strlcpy(buf,s,size) >= size)
                        return NULL;
-               strcpy(buf,s);
-               ret=buf;
                }
        else
                {
@@ -218,17 +244,36 @@ const char *RAND_file_name(char *buf, size_t size)
                        s = DEFAULT_HOME;
                        }
 #endif
-               if (s != NULL && (strlen(s)+strlen(RFILE)+2 < size))
+               if (s && *s && strlen(s)+strlen(RFILE)+2 < size)
                        {
-                       strcpy(buf,s);
+                       BUF_strlcpy(buf,s,size);
 #ifndef OPENSSL_SYS_VMS
-                       strcat(buf,"/");
+                       BUF_strlcat(buf,"/",size);
 #endif
-                       strcat(buf,RFILE);
-                       ret=buf;
+                       BUF_strlcat(buf,RFILE,size);
+                       ok = 1;
                        }
                else
                        buf[0] = '\0'; /* no file name */
                }
-       return(ret);
+
+#ifdef __OpenBSD__
+       /* given that all random loads just fail if the file can't be 
+        * seen on a stat, we stat the file we're returning, if it
+        * fails, use /dev/arandom instead. this allows the user to 
+        * use their own source for good random data, but defaults
+        * to something hopefully decent if that isn't available. 
+        */
+
+       if (!ok)
+               if (BUF_strlcpy(buf,"/dev/arandom",size) >= size) {
+                       return(NULL);
+               }       
+       if (stat(buf,&sb) == -1)
+               if (BUF_strlcpy(buf,"/dev/arandom",size) >= size) {
+                       return(NULL);
+               }       
+
+#endif
+       return(buf);
        }