Do not use uninitialized memory to seed the PRNG as it may confuse

[openssl.git] / crypto / rand / randfile.c

diff --git a/crypto/rand/randfile.c b/crypto/rand/randfile.c
index 7c2673a61ffd31fabd4d05245976697834cdfa4a..43053b19bf8679b878d026760e5d5877fb715519 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 500
+
 #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>
@@ -71,9 +75,7 @@
 #ifndef NO_SYS_TYPES_H
 # include <sys/types.h>
 #endif
-#ifdef MAC_OS_pre_X
-# include <stat.h>
-#else
+#ifndef OPENSSL_NO_POSIX_IO
 # include <sys/stat.h>
 #endif
 
@@ -92,20 +94,32 @@ int RAND_load_file(const char *file, long bytes)
         * if bytes == -1, read complete file. */
 
        MS_STATIC unsigned char buf[BUFSIZE];
+#ifndef OPENSSL_NO_POSIX_IO
        struct stat sb;
+#endif
        int i,ret=0,n;
        FILE *in;
 
        if (file == NULL) return(0);
 
-       i=stat(file,&sb);
-       /* If the state fails, put some crap in anyway */
-       RAND_add(&sb,sizeof(sb),0);
-       if (i < 0) return(0);
+#ifndef OPENSSL_NO_POSIX_IO
+       if (stat(file,&sb) < 0) return(0);
+       RAND_add(&sb,sizeof(sb),0.0);
+#endif
        if (bytes == 0) return(ret);
 
        in=fopen(file,"rb");
        if (in == NULL) goto err;
+#if defined(S_IFBLK) && defined(S_IFCHR) && !defined(OPNESSL_NO_POSIX_IO)
+       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 */
+       }
+#endif
        for (;;)
                {
                if (bytes > 0)
@@ -115,7 +129,7 @@ int RAND_load_file(const char *file, long bytes)
                i=fread(buf,1,n,in);
                if (i <= 0) break;
                /* even if n != i, use the full array */
-               RAND_add(buf,n,i);
+               RAND_add(buf,n,(double)i);
                ret+=i;
                if (bytes > 0)
                        {
@@ -124,7 +138,7 @@ int RAND_load_file(const char *file, long bytes)
                        }
                }
        fclose(in);
-       memset(buf,0,BUFSIZE);
+       OPENSSL_cleanse(buf,BUFSIZE);
 err:
        return(ret);
        }
@@ -135,8 +149,26 @@ int RAND_write_file(const char *file)
        int i,ret=0,rand_err=0;
        FILE *out = NULL;
        int n;
+#ifndef OPENSSL_NO_POSIX_IO
+       struct stat sb;
        
-#if defined(O_CREAT) && !defined(OPENSSL_SYS_WIN32)
+       i=stat(file,&sb);
+       if (i != -1) { 
+#if defined(S_IFBLK) && defined(S_IFCHR)
+         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); 
+         }
+#endif
+       }
+#endif
+
+#if defined(O_CREAT) && !defined(OPENSSL_SYS_WIN32) && !defined(OPENSSL_NO_POSIX_IO)
+       {
        /* For some reason Win32 can't write to files created this way */
        
        /* chmod(..., 0600) is too late to protect the file,
@@ -144,6 +176,7 @@ int RAND_write_file(const char *file)
        int fd = open(file, O_CREAT, 0600);
        if (fd != -1)
                out = fdopen(fd, "wb");
+       }
 #endif
        if (out == NULL)
                out = fopen(file,"wb");
@@ -189,7 +222,7 @@ int RAND_write_file(const char *file)
 #endif /* OPENSSL_SYS_VMS */
 
        fclose(out);
-       memset(buf,0,BUFSIZE);
+       OPENSSL_cleanse(buf,BUFSIZE);
 err:
        return (rand_err ? -1 : ret);
        }
@@ -197,16 +230,17 @@ 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 +252,36 @@ 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);
        }