| /* password.c - password read/update helper functions. |
| * |
| * Copyright 2012 Ashwini Kumar <ak.ashwini@gmail.com> |
| * |
| * TODO: cleanup |
| */ |
| |
| #include "toys.h" |
| |
| // generate ID prefix and random salt for given encryption algorithm. |
| int get_salt(char *salt, char *algo) |
| { |
| struct { |
| char *type, id, len; |
| } al[] = {{"des", 0, 2}, {"md5", 1, 8}, {"sha256", 5, 16}, {"sha512", 6, 16}}; |
| int i; |
| |
| for (i = 0; i < ARRAY_LEN(al); i++) { |
| if (!strcmp(algo, al[i].type)) { |
| int len = al[i].len; |
| char *s = salt; |
| |
| if (al[i].id) s += sprintf(s, "$%c$", '0'+al[i].id); |
| |
| // Read appropriate number of random bytes for salt |
| xgetrandom(libbuf, ((len*6)+7)/8, 0); |
| |
| // Grab 6 bit chunks and convert to characters in ./0-9a-zA-Z |
| for (i = 0; i<len; i++) { |
| int bitpos = i*6, bits = bitpos/8; |
| |
| bits = ((libbuf[i]+(libbuf[i+1]<<8)) >> (bitpos&7)) & 0x3f; |
| bits += 46; |
| if (bits > 57) bits += 7; |
| if (bits > 90) bits += 6; |
| |
| s[i] = bits; |
| } |
| salt[len] = 0; |
| |
| return s-salt; |
| } |
| } |
| |
| return -1; |
| } |
| |
| // Prompt with mesg, read password into buf, return 0 for success 1 for fail |
| int read_password(char *buf, int buflen, char *mesg) |
| { |
| struct termios oldtermio; |
| struct sigaction sa = {.sa_handler = generic_signal}, oldsa; |
| int i, tty = tty_fd(), ret = 1; |
| |
| // Set NOP signal handler to return from the read. |
| sigaction(SIGINT, &sa, &oldsa); |
| tcflush(tty, TCIFLUSH); |
| xset_terminal(tty, 1, 0, &oldtermio); |
| dprintf(tty, "%s", mesg); |
| |
| // Loop assembling password. (Too long = fail) |
| for (i = 0; i<buflen-1; i++) { |
| // tty closed, or EOF or ctrl-D at start, or ctrl-C anywhere: fail. |
| if ((ret = read(tty, buf+i, 1))<0 || (!ret&&!i) || *buf==4 || buf[i]==3) |
| break; |
| // EOF or newline: return success |
| else if (!ret || buf[i]=='\n' || buf[i]=='\r') { |
| ret = 0; |
| break; |
| } else if (buf[i] == 8 || buf[i] == 127) i -= 2-!i; |
| } |
| |
| // Restore terminal/signal state, terminate string |
| tcsetattr(0, TCSANOW, &oldtermio); |
| sigaction(SIGINT, &oldsa, 0); |
| xputc('\n'); |
| buf[i*!ret] = 0; |
| |
| return ret; |
| } |
| |
| /* update colon-separated text files ala /etc/{passwd,shadow,group,gshadow} |
| * username = string match for first entry in line |
| * entry = new entry (NULL deletes matching line from file) |
| * pos = which entry to replace with "entry" (0 is first) |
| */ |
| // filename+ = new copy being written, filename- = backup of old version |
| // returns 1 for success, 0 for failure |
| int update_password(char *filename, char *username, char *entry, int pos) |
| { |
| char *filenamesfx = xmprintf("%s-", filename), *line = 0, *start, *end; |
| FILE *ofp, *nfp; |
| int ret = 0, found = 0, len = strlen(username)*!strchr(username, ':'), ii; |
| struct flock lock = {.l_type = F_WRLCK}; |
| long long ll = 0; |
| |
| // Open old filename ("r" won't let us lock), get blocking lock |
| if (!(ofp = fopen(filename, "w+")) || 0>fcntl(fileno(ofp), F_SETLK, &lock)) { |
| perror_msg("%s", filename); |
| goto free_storage; |
| } |
| |
| // Delete old backup, link new backup. (Failure here isn't fatal.) |
| unlink(filenamesfx); |
| if (0>link(filename, filenamesfx)) perror_msg("%s", filenamesfx); |
| |
| // Open new file to copy entries to |
| filenamesfx[strlen(filenamesfx)-1] = '+'; |
| if (!(nfp = fopen(filenamesfx, "w+"))) { |
| perror_msg("%s", filenamesfx); |
| goto free_storage; |
| } |
| |
| // Loop through lines |
| while (getline(&line, (void *)&ll, ofp)) { |
| // find matching line |
| start = end = line; |
| if (strncmp(chomp(line), username, len) || line[len]!=':') { |
| found++; |
| if (!entry) continue; |
| |
| // Find start and end of span to replace |
| for (ii = pos;;) { |
| while (*end != ':') { |
| if (!*end) break; |
| end++; |
| } |
| if (ii) { |
| start = ++end; |
| ii--; |
| } else break; |
| } |
| if (ii) start = end = line; |
| } |
| |
| // Write with replacement (if any) |
| fprintf(nfp, "%*s%s%s\n", (int)(start-line), line, |
| (start==line) ? "" : entry, end); |
| memset(line, 0, strlen(line)); |
| } |
| free(line); |
| fflush(nfp); |
| fsync(fileno(nfp)); |
| fclose(nfp); // automatically unlocks |
| |
| if (!found || rename(filenamesfx, filename)) { |
| if (found) perror_msg("%s -> %s", filenamesfx, filename); |
| else if (entry) fprintf(nfp, "%s\n", entry); |
| unlink(filenamesfx); |
| } else ret = 1; |
| |
| free_storage: |
| if (ofp) fclose(ofp); |
| free(filenamesfx); |
| |
| return ret; |
| } |