X-Git-Url: http://andersk.mit.edu/gitweb/gssapi-openssh.git/blobdiff_plain/c9f39d2c2cb442069d6568c47f70168e1f255e15..HEAD:/openssh/ssh-rand-helper.c diff --git a/openssh/ssh-rand-helper.c b/openssh/ssh-rand-helper.c index 2d8707e..8b1c4b4 100644 --- a/openssh/ssh-rand-helper.c +++ b/openssh/ssh-rand-helper.c @@ -24,6 +24,30 @@ #include "includes.h" +#include +#include +#include +#include +#include + +#include +#include +#include + +#include +#include + +#ifdef HAVE_SYS_UN_H +# include +#endif + +#include +#include +#include +#include +#include +#include + #include #include #include @@ -39,8 +63,6 @@ #include "pathnames.h" #include "log.h" -RCSID("$Id$"); - /* Number of bytes we write out */ #define OUTPUT_SEED_SIZE 48 @@ -123,7 +145,7 @@ get_random_bytes_prngd(unsigned char *buf, int len, unsigned short tcp_port, char *socket_path) { int fd, addr_len, rval, errors; - char msg[2]; + u_char msg[2]; struct sockaddr_storage addr; struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr; struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr; @@ -135,8 +157,8 @@ get_random_bytes_prngd(unsigned char *buf, int len, if (socket_path != NULL && strlen(socket_path) >= sizeof(addr_un->sun_path)) fatal("Random pool path is too long"); - if (len > 255) - fatal("Too many bytes to read from PRNGD"); + if (len <= 0 || len > 255) + fatal("Too many bytes (%d) to read from PRNGD", len); memset(&addr, '\0', sizeof(addr)); @@ -190,7 +212,7 @@ reopen: goto done; } - if (atomicio(read, fd, buf, len) != len) { + if (atomicio(read, fd, buf, len) != (size_t)len) { if (errno == EPIPE && errors < 10) { close(fd); errors++; @@ -209,6 +231,22 @@ done: return rval; } +static int +seed_from_prngd(unsigned char *buf, size_t bytes) +{ +#ifdef PRNGD_PORT + debug("trying egd/prngd port %d", PRNGD_PORT); + if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0) + return 0; +#endif +#ifdef PRNGD_SOCKET + debug("trying egd/prngd socket %s", PRNGD_SOCKET); + if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0) + return 0; +#endif + return -1; +} + double stir_gettimeofday(double entropy_estimate) { @@ -382,8 +420,8 @@ hash_command_output(entropy_cmd_t *src, unsigned char *hash) debug3("Time elapsed: %d msec", msec_elapsed); if (waitpid(pid, &status, 0) == -1) { - error("Couldn't wait for child '%s' completion: %s", - src->cmdstring, strerror(errno)); + error("Couldn't wait for child '%s' completion: %s", + src->cmdstring, strerror(errno)); return 0.0; } @@ -534,10 +572,11 @@ prng_check_seedfile(char *filename) void prng_write_seedfile(void) { - int fd; + int fd, save_errno; unsigned char seed[SEED_FILE_SIZE]; - char filename[MAXPATHLEN]; + char filename[MAXPATHLEN], tmpseed[MAXPATHLEN]; struct passwd *pw; + mode_t old_umask; pw = getpwuid(getuid()); if (pw == NULL) @@ -547,12 +586,16 @@ prng_write_seedfile(void) /* Try to ensure that the parent directory is there */ snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, _PATH_SSH_USER_DIR); - mkdir(filename, 0700); + if (mkdir(filename, 0700) < 0 && errno != EEXIST) + fatal("mkdir %.200s: %s", filename, strerror(errno)); snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, SSH_PRNG_SEED_FILE); - debug("writing PRNG seed to file %.100s", filename); + strlcpy(tmpseed, filename, sizeof(tmpseed)); + if (strlcat(tmpseed, ".XXXXXXXXXX", sizeof(tmpseed)) >= + sizeof(tmpseed)) + fatal("PRNG seed filename too long"); if (RAND_bytes(seed, sizeof(seed)) <= 0) fatal("PRNG seed extraction failed"); @@ -560,15 +603,31 @@ prng_write_seedfile(void) /* 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) { - debug("WARNING: couldn't access PRNG seedfile %.100s " - "(%.100s)", filename, strerror(errno)); + old_umask = umask(0177); + + if ((fd = mkstemp(tmpseed)) == -1) { + debug("WARNING: couldn't make temporary PRNG seedfile %.100s " + "(%.100s)", tmpseed, strerror(errno)); } else { - if (atomicio(vwrite, fd, &seed, sizeof(seed)) < sizeof(seed)) + debug("writing PRNG seed to file %.100s", tmpseed); + if (atomicio(vwrite, fd, &seed, sizeof(seed)) < sizeof(seed)) { + save_errno = errno; + close(fd); + unlink(tmpseed); fatal("problem writing PRNG seedfile %.100s " - "(%.100s)", filename, strerror(errno)); + "(%.100s)", filename, strerror(save_errno)); + } close(fd); + debug("moving temporary PRNG seed to file %.100s", filename); + if (rename(tmpseed, filename) == -1) { + save_errno = errno; + unlink(tmpseed); + fatal("problem renaming PRNG seedfile from %.100s " + "to %.100s (%.100s)", tmpseed, filename, + strerror(save_errno)); + } } + umask(old_umask); } void @@ -629,8 +688,7 @@ prng_read_commands(char *cmdfilename) } num_cmds = 64; - entcmd = xmalloc(num_cmds * sizeof(entropy_cmd_t)); - memset(entcmd, '\0', num_cmds * sizeof(entropy_cmd_t)); + entcmd = xcalloc(num_cmds, sizeof(entropy_cmd_t)); /* Read in file */ cur_cmd = linenum = 0; @@ -723,7 +781,7 @@ prng_read_commands(char *cmdfilename) */ if (cur_cmd == num_cmds) { num_cmds *= 2; - entcmd = xrealloc(entcmd, num_cmds * + entcmd = xrealloc(entcmd, num_cmds, sizeof(entropy_cmd_t)); } } @@ -732,12 +790,13 @@ prng_read_commands(char *cmdfilename) memset(&entcmd[cur_cmd], '\0', sizeof(entropy_cmd_t)); /* trim to size */ - entropy_cmds = xrealloc(entcmd, (cur_cmd + 1) * + entropy_cmds = xrealloc(entcmd, (cur_cmd + 1), sizeof(entropy_cmd_t)); debug("Loaded %d entropy commands from %.100s", cur_cmd, cmdfilename); + fclose(f); return cur_cmd < MIN_ENTROPY_SOURCES ? -1 : 0; } @@ -747,7 +806,7 @@ usage(void) fprintf(stderr, "Usage: %s [options]\n", __progname); fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); fprintf(stderr, " Multiple -v increases verbosity.\n"); - fprintf(stderr, " -x Force output in hexidecimal (for debugging)\n"); + fprintf(stderr, " -x Force output in hexadecimal (for debugging)\n"); fprintf(stderr, " -X Force output in binary\n"); fprintf(stderr, " -b bytes Number of bytes to output (default %d)\n", OUTPUT_SEED_SIZE); @@ -815,21 +874,16 @@ main(int argc, char **argv) debug("Seeded RNG with %i bytes from system calls", (int)stir_from_system()); -#ifdef PRNGD_PORT - if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == -1) - fatal("Entropy collection failed"); - RAND_add(buf, bytes, bytes); -#elif defined(PRNGD_SOCKET) - if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == -1) - fatal("Entropy collection failed"); - RAND_add(buf, bytes, bytes); -#else - /* Read in collection commands */ - if (prng_read_commands(SSH_PRNG_COMMAND_FILE) == -1) - fatal("PRNG initialisation failed -- exiting."); - debug("Seeded RNG with %i bytes from programs", - (int)stir_from_programs()); -#endif + /* try prngd, fall back to commands if prngd fails or not configured */ + if (seed_from_prngd(buf, bytes) == 0) { + RAND_add(buf, bytes, bytes); + } else { + /* Read in collection commands */ + if (prng_read_commands(SSH_PRNG_COMMAND_FILE) == -1) + fatal("PRNG initialisation failed -- exiting."); + debug("Seeded RNG with %i bytes from programs", + (int)stir_from_programs()); + } #ifdef USE_SEED_FILES prng_write_seedfile(); @@ -857,3 +911,15 @@ main(int argc, char **argv) return ret == bytes ? 0 : 1; } + +/* + * We may attempt to re-seed during mkstemp if we are using the one in the + * compat library (via mkstemp -> _gettemp -> arc4random -> seed_rng) so we + * need our own seed_rng(). We must also check that we have enough entropy. + */ +void +seed_rng(void) +{ + if (!RAND_status()) + fatal("Not enough entropy in RNG"); +}