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authorDamien Miller <djm@mindrot.org>2000-04-30 09:30:44 +1000
committerDamien Miller <djm@mindrot.org>2000-04-30 09:30:44 +1000
commit4018c1985d6e34f4625132965e814880ac3075ba (patch)
tree1a3450e78dc2fa600f485a07a5c5a866781f082c /entropy.c
parent1bead335d7381b553bc4a13b3ea2b9dc09679123 (diff)
- Integrate Andre Lucas' <andre.lucas@dial.pipex.com> entropy collection
patch. - Adds timeout to entropy collection - Disables slow entropy sources - Load and save seed file - Changed entropy seed code to user per-user seeds only (server seed is saved in root's .ssh directory) - Use atexit() and fatal cleanups to save seed on exit
Diffstat (limited to 'entropy.c')
-rw-r--r--entropy.c384
1 files changed, 304 insertions, 80 deletions
diff --git a/entropy.c b/entropy.c
index 549fe702..edf14233 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) */