1 files changed, 304 insertions, 80 deletions

diff --git a/entropy.c b/entropy.c
index 549fe7026..edf142333 100644
--- a/entropy.c
+++ b/entropy.c
@@ -35,7 +35,7 @@
 #include <openssl/rand.h>
 #include <openssl/sha.h>
 
-RCSID("$Id: entropy.c,v 1.5 2000/04/16 02:31:50 damien Exp $");
+RCSID("$Id: entropy.c,v 1.6 2000/04/29 23:30:46 damien Exp $");
 
 #ifdef EGD_SOCKET
 #ifndef offsetof
@@ -109,87 +109,100 @@ void get_random_bytes(unsigned char *buf, int len)
 #if !defined(EGD_SOCKET) && !defined(RANDOM_POOL)
 /* 
  * FIXME: proper entropy estimations. All current values are guesses
- * FIXME: Need timeout for slow moving programs
+ * FIXME: (ATL) do estimates at compile time?
  * FIXME: More entropy sources
+ * FIXME: (ATL) bring in entropy sources from file
+ * FIXME: (ATL) add heuristic to increase the timeout if needed
  */
 
-double stir_from_system(void);
-double stir_from_programs(void);
-double stir_gettimeofday(double entropy_estimate);
-double stir_clock(double entropy_estimate);
-double stir_rusage(int who, double entropy_estimate);
-double hash_output_from_command(const char *path, const char **args, char *hash);
+/* slow command timeouts (all in milliseconds) */
+/* 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;         
 
 typedef struct
 {
         /* Proportion of data that is entropy */
         double rate;
+        /* Counter goes positive if this command times out */
+        unsigned int badness;
+        /* Increases by factor of two each timeout */
+        unsigned int sticky_badness;
         /* Path to executable */
         const char *path;
         /* argv to pass to executable */
         const char *args[5];
 } entropy_source_t;
 
+double stir_from_system(void);
+double stir_from_programs(void);
+double stir_gettimeofday(double entropy_estimate);
+double stir_clock(double entropy_estimate);
+double stir_rusage(int who, double entropy_estimate);
+double hash_output_from_command(entropy_source_t *src, char *hash);
+
 entropy_source_t entropy_sources[] = {
 #ifdef PROG_LS
-        { 0.002, PROG_LS,       { "ls", "-alni", "/var/log", NULL } },
-        { 0.002, PROG_LS,       { "ls", "-alni", "/var/adm", NULL } },
-        { 0.002, PROG_LS,       { "ls", "-alni", "/var/mail", NULL } },
-        { 0.002, PROG_LS,       { "ls", "-alni", "/var/spool/mail", NULL } },
-        { 0.002, PROG_LS,       { "ls", "-alni", "/proc", NULL } },
-        { 0.002, PROG_LS,       { "ls", "-alni", "/tmp", NULL } },
+        { 0.002, 0, 1, PROG_LS,       { "ls", "-alni", "/var/log", NULL } },
+        { 0.002, 0, 1, PROG_LS,       { "ls", "-alni", "/var/adm", NULL } },
+        { 0.002, 0, 1, PROG_LS,       { "ls", "-alni", "/var/mail", NULL } },
+        { 0.002, 0, 1, PROG_LS,       { "ls", "-alni", "/var/spool/mail", NULL } },
+        { 0.002, 0, 1, PROG_LS,       { "ls", "-alni", "/proc", NULL } },
+        { 0.002, 0, 1, PROG_LS,       { "ls", "-alni", "/tmp", NULL } },
 #endif
 #ifdef PROG_NETSTAT
-        { 0.005, PROG_NETSTAT,  { "netstat","-an", NULL, NULL } },
-        { 0.010, PROG_NETSTAT,  { "netstat","-in", NULL, NULL } },
-        { 0.002, PROG_NETSTAT,  { "netstat","-rn", NULL, NULL } },
-        { 0.002, PROG_NETSTAT,  { "netstat","-s", NULL, NULL } },
+        { 0.005, 0, 1, PROG_NETSTAT,  { "netstat","-an", NULL, NULL } },
+        { 0.010, 0, 1, PROG_NETSTAT,  { "netstat","-in", NULL, NULL } },
+        { 0.002, 0, 1, PROG_NETSTAT,  { "netstat","-rn", NULL, NULL } },
+        { 0.002, 0, 1, PROG_NETSTAT,  { "netstat","-s", NULL, NULL } },
 #endif
 #ifdef PROG_ARP
-        { 0.002, PROG_ARP,      { "arp","-a","-n", NULL } },
+        { 0.002, 0, 1, PROG_ARP,      { "arp","-a","-n", NULL } },
 #endif
 #ifdef PROG_IFCONFIG
-        { 0.002, PROG_IFCONFIG, { "ifconfig", "-a", NULL, NULL } },
+        { 0.002, 0, 1, PROG_IFCONFIG, { "ifconfig", "-a", NULL, NULL } },
 #endif
 #ifdef PROG_PS
-        { 0.003, PROG_PS,       { "ps", "laxww", NULL, NULL } },
-        { 0.003, PROG_PS,       { "ps", "-al", NULL, NULL } },
-        { 0.003, PROG_PS,       { "ps", "-efl", NULL, NULL } },
+        { 0.003, 0, 1, PROG_PS,       { "ps", "laxww", NULL, NULL } },
+        { 0.003, 0, 1, PROG_PS,       { "ps", "-al", NULL, NULL } },
+        { 0.003, 0, 1, PROG_PS,       { "ps", "-efl", NULL, NULL } },
 #endif
 #ifdef PROG_W
-        { 0.005, PROG_W,        { "w", NULL, NULL, NULL } },
+        { 0.005, 0, 1, PROG_W,        { "w", NULL, NULL, NULL } },
 #endif
 #ifdef PROG_WHO
-        { 0.001, PROG_WHO,      { "who","-i", NULL, NULL } },
+        { 0.001, 0, 1, PROG_WHO,      { "who","-i", NULL, NULL } },
 #endif
 #ifdef PROG_LAST
-        { 0.001, PROG_LAST,     { "last", NULL, NULL, NULL } },
+        { 0.001, 0, 1, PROG_LAST,     { "last", NULL, NULL, NULL } },
 #endif
 #ifdef PROG_LASTLOG
-        { 0.001, PROG_LASTLOG,  { "lastlog", NULL, NULL, NULL } },
+        { 0.001, 0, 1, PROG_LASTLOG,  { "lastlog", NULL, NULL, NULL } },
 #endif
 #ifdef PROG_DF
-        { 0.010, PROG_DF,       { "df", NULL, NULL, NULL } },
-        { 0.010, PROG_DF,       { "df", "-i", NULL, NULL } },
+        { 0.010, 0, 1, PROG_DF,       { "df", NULL, NULL, NULL } },
+        { 0.010, 0, 1, PROG_DF,       { "df", "-i", NULL, NULL } },
 #endif
 #ifdef PROG_VMSTAT
-        { 0.010, PROG_VMSTAT,   { "vmstat", NULL, NULL, NULL } },
+        { 0.010, 0, 1, PROG_VMSTAT,   { "vmstat", NULL, NULL, NULL } },
 #endif
 #ifdef PROG_UPTIME
-        { 0.001, PROG_UPTIME,   { "uptime", NULL, NULL, NULL } },
+        { 0.001, 0, 1, PROG_UPTIME,   { "uptime", NULL, NULL, NULL } },
 #endif
 #ifdef PROG_IPCS
-        { 0.001, PROG_IPCS,     { "-a", NULL, NULL, NULL } },
+        { 0.001, 0, 1, PROG_IPCS,     { "-a", NULL, NULL, NULL } },
 #endif
 #ifdef PROG_TAIL
-        { 0.001, PROG_TAIL,     { "tail", "-200", "/var/log/messages", NULL, NULL } },
-        { 0.001, PROG_TAIL,     { "tail", "-200", "/var/log/syslog", NULL, NULL } },
-        { 0.001, PROG_TAIL,     { "tail", "-200", "/var/adm/messages", NULL, NULL } },
-        { 0.001, PROG_TAIL,     { "tail", "-200", "/var/adm/syslog", NULL, NULL } },
-        { 0.001, PROG_TAIL,     { "tail", "-200", "/var/log/maillog", NULL, NULL } },
-        { 0.001, PROG_TAIL,     { "tail", "-200", "/var/adm/maillog", NULL, NULL } },
+        { 0.001, 0, 1, PROG_TAIL,     { "tail", "-200", "/var/log/messages", NULL, NULL } },
+        { 0.001, 0, 1, PROG_TAIL,     { "tail", "-200", "/var/log/syslog", NULL, NULL } },
+        { 0.001, 0, 1, PROG_TAIL,     { "tail", "-200", "/var/adm/messages", NULL, NULL } },
+        { 0.001, 0, 1, PROG_TAIL,     { "tail", "-200", "/var/adm/syslog", NULL, NULL } },
+        { 0.001, 0, 1, PROG_TAIL,     { "tail", "-200", "/var/log/maillog", NULL, NULL } },
+        { 0.001, 0, 1, PROG_TAIL,     { "tail", "-200", "/var/adm/maillog", NULL, NULL } },
 #endif
-        { 0.000, NULL,          { NULL, NULL, NULL, NULL, NULL } },
+        { 0.000, 0, 0, NULL,          { NULL, NULL, NULL, NULL, NULL } },
 };
 
 double 
@@ -236,37 +249,49 @@ stir_from_programs(void)
         for(i = 0; i < 2; i++) {
                 c = 0;
                 while (entropy_sources[c].path != NULL) {
-                        /* Hash output from command */
-                        entropy_estimate = hash_output_from_command(entropy_sources[c].path,
-                                entropy_sources[c].args, hash);
 
-                        /* Scale back entropy estimate according to command's rate */
-                        entropy_estimate *= entropy_sources[c].rate;
+                        if (!entropy_sources[c].badness) {
+                                /* Hash output from command */
+                                entropy_estimate = hash_output_from_command(&entropy_sources[c], hash);
+
+                                /* Scale back entropy estimate according to command's rate */
+                                entropy_estimate *= entropy_sources[c].rate;
  
-                        /* Upper bound of entropy estimate is SHA_DIGEST_LENGTH */
-                        if (entropy_estimate > SHA_DIGEST_LENGTH)
-                                entropy_estimate = SHA_DIGEST_LENGTH;
+                                /* Upper bound of entropy estimate is SHA_DIGEST_LENGTH */
+                                if (entropy_estimate > SHA_DIGEST_LENGTH)
+                                        entropy_estimate = SHA_DIGEST_LENGTH;
 
                         /* * Scale back estimates for subsequent passes through list */
-                        entropy_estimate /= 10.0 * (i + 1.0);
+                                entropy_estimate /= 10.0 * (i + 1.0);
                         
-                        /* Stir it in */
-                        RAND_add(hash, sizeof(hash), entropy_estimate);
+                                /* Stir it in */
+                                RAND_add(hash, sizeof(hash), entropy_estimate);
 
 /* FIXME: turn this off later */
 #if 1
-                        debug("Got %0.2f bytes of entropy from %s", entropy_estimate, 
-                                entropy_sources[c].path);
+                                debug("Got %0.2f bytes of entropy from %s", entropy_estimate, 
+                                        entropy_sources[c].path);
 #endif
 
-                        total_entropy_estimate += entropy_estimate;
+                                total_entropy_estimate += entropy_estimate;
 
                         /* Execution times should be a little unpredictable */
-                        total_entropy_estimate += stir_gettimeofday(0.05);
-                        total_entropy_estimate += stir_clock(0.05);
-                        total_entropy_estimate += stir_rusage(RUSAGE_SELF, 0.1);
-                        total_entropy_estimate += stir_rusage(RUSAGE_CHILDREN, 0.1);
-                        
+                                total_entropy_estimate += stir_gettimeofday(0.05);
+                                total_entropy_estimate += stir_clock(0.05);
+                                total_entropy_estimate += stir_rusage(RUSAGE_SELF, 0.1);
+                                total_entropy_estimate += stir_rusage(RUSAGE_CHILDREN, 0.1);
+                        } else {
+/* FIXME: turn this off later */
+#if 1
+                                debug("Command '%s %s %s' disabled (badness %d)",
+                                        entropy_sources[c].path, entropy_sources[c].args[1],
+                                        entropy_sources[c].args[2], entropy_sources[c].badness);
+#endif
+
+                                if (entropy_sources[c].badness > 0)
+                                        entropy_sources[c].badness--;
+                        }
+
                         c++;
                 }
         }
@@ -308,7 +333,7 @@ stir_rusage(int who, double entropy_estimate)
 #ifdef HAVE_GETRUSAGE
         struct rusage ru;
         
-   if (getrusage(who, &ru) == -1)
+        if (getrusage(who, &ru) == -1)
                 fatal("Couldn't getrusage: %s", strerror(errno));
 
         RAND_add(&ru, sizeof(ru), 0.1);
@@ -320,10 +345,12 @@ stir_rusage(int who, double entropy_estimate)
 }
 
 double
-hash_output_from_command(const char *path, const char **args, char *hash)
+hash_output_from_command(entropy_source_t *src, char *hash)
 {
         static int devnull = -1;
         int p[2];
+        fd_set rdset;
+        int cmd_eof = 0, error_abort = 0;
         pid_t pid;
         int status;
         char buf[2048];
@@ -347,18 +374,17 @@ hash_output_from_command(const char *path, const char **args, char *hash)
                         fatal("Couldn't fork: %s", strerror(errno));
                         /* NOTREACHED */
                 case 0: /* Child */
-                        close(0);
-                        close(1);
-                        close(2);
-                        dup2(devnull, 0);
-                        dup2(p[1], 1);
-                        dup2(p[1], 2);
+                        dup2(devnull, STDIN_FILENO);
+                        dup2(p[1], STDOUT_FILENO);
+                        dup2(p[1], STDERR_FILENO);
                         close(p[0]);
                         close(p[1]);
                         close(devnull);
 
-                        execv(path, (char**)args);
-                        debug("(child) Couldn't exec '%s': %s", path, strerror(errno));
+                        execv(src->path, (char**)(src->args));
+                        debug("(child) Couldn't exec '%s %s %s': %s", src->path,
+                                src->args[1], src->args[2], strerror(errno));
+                        src->badness = src->sticky_badness = 128;
                         _exit(-1);
                 default: /* Parent */
                         break;
@@ -371,31 +397,208 @@ hash_output_from_command(const char *path, const char **args, char *hash)
         /* Hash output from child */
         SHA1_Init(&sha);
         total_bytes_read = 0;
-        while ((bytes_read = read(p[0], buf, sizeof(buf)))      > 0) {
-                SHA1_Update(&sha, buf, bytes_read);
-                total_bytes_read += bytes_read;
-                RAND_add(&bytes_read, sizeof(&bytes_read), 0.0);
-        }
+
+        while (!error_abort && !cmd_eof) {
+                int ret;
+                struct timeval tv;
+
+                FD_ZERO(&rdset);
+                FD_SET(p[0], &rdset);
+                tv.tv_sec = entropy_timeout_current / 1000;
+                tv.tv_usec = (entropy_timeout_current % 1000) * 1000;
+
+                ret = select(p[0]+1, &rdset, NULL, NULL, &tv);
+                switch (ret) {
+                case 0:
+                        /* timer expired */
+                        error_abort = 1;
+                        break;
+                        
+                case 1:
+                        /* command input */
+                        bytes_read = read(p[0], buf, sizeof(buf));
+                        if (bytes_read == -1) {
+                                error_abort = 1;
+                                break;
+                        }
+                        SHA1_Update(&sha, buf, bytes_read);
+                        total_bytes_read += bytes_read;
+                        RAND_add(&bytes_read, sizeof(&bytes_read), 0.0);
+                        cmd_eof = bytes_read ? 0 : 1;
+
+                        break;
+
+                case -1:
+                default:
+                        error("Command '%s %s': select() failed: %s", src->path, src->args[1],
+                                strerror(errno));
+                        error_abort = 1;
+                        break;
+                } /* switch ret */
+
+                RAND_add(&tv, sizeof(&tv), 0.0);
+        } /* while !error_abort && !cmd_eof */
+
         SHA1_Final(hash, &sha);
 
         close(p[0]);
         
         if (waitpid(pid, &status, 0) == -1) {
-                error("Couldn't wait for child '%s' completion: %s", path, 
-                        strerror(errno));
-                return(-1);
+                error("Couldn't wait for child '%s %s' completion: %s", src->path,
+                        src->args[1], strerror(errno));
+                /* return(-1); */ /* FIXME: (ATL) this doesn't feel right */
+                return(0.0);
         }
 
         RAND_add(&status, sizeof(&status), 0.0);
 
-        if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0))
-                return(0.0);
-        else
+        if (error_abort) {
+                /* closing p[0] on timeout causes the entropy command to
+                 * SIGPIPE. Take whatever output we got, and mark this command
+                 * as slow */
+                debug("Command %s %s timed out", src->path, src->args[1]);
+                src->sticky_badness *= 2;
+                src->badness = src->sticky_badness;
                 return(total_bytes_read);
+        }
+
+        if (WIFEXITED(status)) {
+                if (WEXITSTATUS(status)==0) {
+                        return(total_bytes_read);
+                } else {
+                        debug("Exit status was %d", WEXITSTATUS(status));
+                        src->badness = src->sticky_badness = 128;
+                        return (0.0);
+                }
+        } else if (WIFSIGNALED(status)) {
+                debug("Returned on uncaught signal %d !", status);
+                src->badness = src->sticky_badness = 128;
+                return(0.0);
+        } else
+                return(0.0);
+}
+
+/*
+ * prng seedfile functions
+ */
+int
+prng_check_seedfile(char *filename) {
+
+        struct stat st;
+
+        /* FIXME raceable: eg replace seed between this stat and subsequent open */
+        /* Not such a problem because we don't trust the seed file anyway */
+        if (lstat(filename, &st) == -1) {
+                /* Fail on hard errors */
+                if (errno != ENOENT)
+                        fatal("Couldn't stat random seed file \"%s\": %s", filename,
+                                strerror(errno));
+
+                return(0);
+        }
+
+        /* regular file? */
+        if (!S_ISREG(st.st_mode))
+                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 == geteuid()))
+                fatal("PRNG seedfile %.100s must be mode 0600, owned by uid %d",
+                         filename, getuid());
+
+        return(1);
+}
+
+void
+prng_write_seedfile(void) {
+        int fd;
+        char seed[1024];
+        char filename[1024];
+        struct passwd *pw;
+
+        /* Don't bother if we have already saved a seed */
+        if (prng_seed_saved)
+                return;
+        
+        pw = getpwuid(getuid());
+        if (pw == NULL)
+                fatal("Couldn't get password entry for current user (%i): %s", 
+                        getuid(), strerror(errno));
+                                
+        /* Try to ensure that the parent directory is there */
+        snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, 
+                SSH_USER_DIR);
+        mkdir(filename, 0700);
+
+        snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, 
+                SSH_PRNG_SEED_FILE);
+
+        debug("writing PRNG seed to file %.100s", filename);
+
+        RAND_bytes(seed, sizeof(seed));
+
+        /* Don't care if the seed doesn't exist */
+        prng_check_seedfile(filename);
+        
+        if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1)
+                fatal("couldn't access PRNG seedfile %.100s (%.100s)", filename, 
+                        strerror(errno));
+        
+        if (atomicio(write, fd, &seed, sizeof(seed)) != sizeof(seed))
+                fatal("problem writing PRNG seedfile %.100s (%.100s)", filename, 
+                         strerror(errno));
+
+        close(fd);
+}
+
+void
+prng_read_seedfile(void) {
+        int fd;
+        char seed[1024];
+        char filename[1024];
+        struct passwd *pw;
+        
+        pw = getpwuid(getuid());
+        if (pw == NULL)
+                fatal("Couldn't get password entry for current user (%i): %s", 
+                        getuid(), strerror(errno));
+                        
+        snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, 
+                SSH_PRNG_SEED_FILE);
+
+        debug("loading PRNG seed from file %.100s", filename);
+
+        if (!prng_check_seedfile(filename)) {
+                verbose("Random seed file not found, creating new");
+                prng_write_seedfile();
+                
+                /* Reseed immediatly */
+                (void)stir_from_system();
+                (void)stir_from_programs();
+                return;
+        }
+
+        /* open the file and read in the seed */
+        fd = open(filename, O_RDONLY);
+        if (fd == -1)
+                fatal("could not open PRNG seedfile %.100s (%.100s)", filename, 
+                        strerror(errno));
+
+        if (atomicio(read, fd, &seed, sizeof(seed)) != sizeof(seed)) {
+                verbose("invalid or short read from PRNG seedfile %.100s - ignoring",
+                        filename);
+                memset(seed, '\0', sizeof(seed));
+        }
+        close(fd);
+
+        /* stir in the seed, with estimated entropy zero */
+        RAND_add(&seed, sizeof(seed), 0.0);
 }
+
 #endif /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */
 
 #if defined(EGD_SOCKET) || defined(RANDOM_POOL)
+
 /*
  * Seed OpenSSL's random number pool from Kernel random number generator
  * or EGD
@@ -410,9 +613,21 @@ seed_rng(void)
         RAND_add(buf, sizeof(buf), sizeof(buf));
         memset(buf, '\0', sizeof(buf));
 }
+
 #else /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */
+
+/*
+ * Write a keyfile at exit
+ */ 
+void
+prng_seed_cleanup(void *junk)
+{
+        prng_write_seedfile();
+}
+
 /*
- * Conditionally Seed OpenSSL's random number pool syscalls and program output
+ * Conditionally Seed OpenSSL's random number pool from
+ * syscalls and program output
  */
 void
 seed_rng(void)
@@ -422,5 +637,14 @@ seed_rng(void)
         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());
+
+        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);
+        }
 }
 #endif /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */