- (djm) Fix pam sprintf fix

 - (djm) Cleanup entropy collection code a little more. Split initialisation
   from seeding, perform intialisation immediatly at start, be careful with
   uids. Based on problem report from Jim Watt <jimw@peisj.pebio.com>

1 files changed, 49 insertions, 40 deletions

diff --git a/entropy.c b/entropy.c
index d8eba6547..842760992 100644
--- a/entropy.c
+++ b/entropy.c
@@ -35,7 +35,7 @@
 #include <openssl/rand.h>
 #include <openssl/sha.h>
 
-RCSID("$Id: entropy.c,v 1.16 2000/06/26 03:55:31 djm Exp $");
+RCSID("$Id: entropy.c,v 1.17 2000/07/09 12:42:33 djm Exp $");
 
 #ifndef offsetof
 # define offsetof(type, member) ((size_t) &((type *)0)->member)
@@ -168,6 +168,9 @@ seed_rng(void)
         memset(buf, '\0', sizeof(buf));
 }
 
+/* No-op */
+void init_rng(void) {}
+
 #else /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */
 
 /* 
@@ -180,9 +183,9 @@ seed_rng(void)
 /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */
 static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC;
 
-static int prng_seed_loaded = 0;
 static int prng_seed_saved = 0;
-static int prng_commands_loaded = 0;
+static int prng_initialised = 0;
+uid_t original_uid;
 
 typedef struct
 {
@@ -395,10 +398,10 @@ hash_output_from_command(entropy_source_t *src, char *hash)
                         close(p[1]);
                         close(devnull);
 
+                        setuid(original_uid);
                         execv(src->path, (char**)(src->args));
                         debug("(child) Couldn't exec '%s': %s", src->cmdstring,
                               strerror(errno));
-                        src->badness = src->sticky_badness = 128;
                         _exit(-1);
                 default: /* Parent */
                         break;
@@ -432,38 +435,36 @@ hash_output_from_command(entropy_source_t *src, char *hash)
 
                 ret = select(p[0]+1, &rdset, NULL, NULL, &tv);
 
+                RAND_add(&tv, sizeof(tv), 0.0);
+
                 switch (ret) {
                 case 0:
                         /* timer expired */
                         error_abort = 1;
                         break;
-                        
                 case 1:
                         /* command input */
                         bytes_read = read(p[0], buf, sizeof(buf));
+                        RAND_add(&bytes_read, sizeof(&bytes_read), 0.0);
                         if (bytes_read == -1) {
                                 error_abort = 1;
                                 break;
-                        }
-                        if (bytes_read) {
+                        } else if (bytes_read) {
                                 SHA1_Update(&sha, buf, bytes_read);
                                 total_bytes_read += bytes_read;
-                                RAND_add(&bytes_read, sizeof(&bytes_read), 0.0);
-                        } else
+                        } else {
                                 cmd_eof = 1;
-
+                        }
                         break;
-
                 case -1:
                 default:
+                        /* error */
                         debug("Command '%s': select() failed: %s", src->cmdstring,
                               strerror(errno));
                         error_abort = 1;
                         break;
-                } /* switch ret */
-
-                RAND_add(&tv, sizeof(&tv), 0.0);
-        } /* while !error_abort && !cmd_eof */
+                }
+        }
 
         SHA1_Final(hash, &sha);
 
@@ -533,7 +534,7 @@ prng_check_seedfile(char *filename) {
                 fatal("PRNG seedfile %.100s is not a regular file", filename);
 
         /* mode 0600, owned by root or the current user? */
-        if (((st.st_mode & 0177) != 0) || !(st.st_uid == getuid()))
+        if (((st.st_mode & 0177) != 0) || !(st.st_uid == original_uid))
                 fatal("PRNG seedfile %.100s must be mode 0600, owned by uid %d",
                          filename, getuid());
 
@@ -551,12 +552,14 @@ prng_write_seedfile(void) {
         if (prng_seed_saved)
                 return;
         
+        setuid(original_uid);
+        
         prng_seed_saved = 1;
         
-        pw = getpwuid(getuid());
+        pw = getpwuid(original_uid);
         if (pw == NULL)
                 fatal("Couldn't get password entry for current user (%i): %s", 
-                        getuid(), strerror(errno));
+                        original_uid, strerror(errno));
                                 
         /* Try to ensure that the parent directory is there */
         snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, 
@@ -591,10 +594,10 @@ prng_read_seedfile(void) {
         char filename[1024];
         struct passwd *pw;
         
-        pw = getpwuid(getuid());
+        pw = getpwuid(original_uid);
         if (pw == NULL)
                 fatal("Couldn't get password entry for current user (%i): %s", 
-                        getuid(), strerror(errno));
+                        original_uid, strerror(errno));
                         
         snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, 
                 SSH_PRNG_SEED_FILE);
@@ -755,7 +758,7 @@ prng_read_commands(char *cmdfilename)
         /* trim to size */
         entropy_sources = xrealloc(entcmd, (cur_cmd+1) * sizeof(entropy_source_t));
 
-        debug("loaded %d entropy commands from %.100s", cur_cmd, cmdfilename);
+        debug("Loaded %d entropy commands from %.100s", cur_cmd, cmdfilename);
 
         return (cur_cmd >= MIN_ENTROPY_SOURCES);
 }
@@ -777,35 +780,41 @@ void
 seed_rng(void)
 {
         void *old_sigchld_handler;
-        
-        if (!prng_commands_loaded) {
-                if (!prng_read_commands(SSH_PRNG_COMMAND_FILE))
-                        fatal("PRNG initialisation failed -- exiting.");
-                prng_commands_loaded = 1;
-        }
 
+        if (!prng_initialised)
+                fatal("RNG not initialised");
+        
         /* Make sure some other sigchld handler doesn't reap our entropy */
         /* commands */
         old_sigchld_handler = signal(SIGCHLD, SIG_DFL);
 
-        debug("Seeding random number generator.");
-        debug("OpenSSL random status is now %i\n", RAND_status());
-        debug("%i bytes from system calls", (int)stir_from_system());
-        debug("%i bytes from programs", (int)stir_from_programs());
-        debug("OpenSSL random status is now %i\n", RAND_status());
+        debug("Seeded RNG with %i bytes from programs", (int)stir_from_programs());
+        debug("Seeded RNG with %i bytes from system calls", (int)stir_from_system());
+
+        if (!RAND_status())
+                fatal("Not enough entropy in RNG");
 
         signal(SIGCHLD, old_sigchld_handler);
 
         if (!RAND_status())
                 fatal("Couldn't initialise builtin random number generator -- exiting.");
+}
 
-        if (!prng_seed_loaded)
-        {
-                prng_seed_loaded = 1;
-                prng_seed_saved = 0;            
-                prng_read_seedfile();
-                fatal_add_cleanup(prng_seed_cleanup, NULL);
-                atexit(prng_write_seedfile);
-        }
+void init_rng(void) 
+{
+        original_uid = getuid();
+
+        /* Read in collection commands */
+        if (!prng_read_commands(SSH_PRNG_COMMAND_FILE))
+                fatal("PRNG initialisation failed -- exiting.");
+
+        /* Set ourselves up to save a seed upon exit */
+        prng_seed_saved = 0;            
+        prng_read_seedfile();
+        fatal_add_cleanup(prng_seed_cleanup, NULL);
+        atexit(prng_write_seedfile);
+
+        prng_initialised = 1;
 }
+
 #endif /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */