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/* password.c - password read/update helper functions.
*
* Copyright 2012 Ashwini Kumar <ak.ashwini@gmail.com>
*/
#include "toys.h"
// generate $id$salt$hash given a password and algorithm. Generates salt if NULL
//char *toy_crypt(char *pass, char *salt, char *algo)
// generate ID prefix and random salt for given encryption algorithm.
int get_salt(char *salt, char *algo, int rand)
{
struct {
char *type, id, len;
} al[] = {{"des", 0, 2}, {"md5", 1, 8}, {"sha256", 5, 16}, {"sha512", 6, 16}};
char *s;
int i, len;
for (i = 0; i < ARRAY_LEN(al); i++) {
for (s = al[i].type, len = 0; algo[len]; len++) {
while (ispunct(algo[len])) len++;
if (tolower(algo[len]) != tolower(*s++)) break;
}
if (algo[len]) continue;
len = al[i].len;
s = salt + (al[i].id ? sprintf(salt, "$%c$", '0'+al[i].id) : 0);
// Read appropriate number of random bytes for salt
if (rand) xgetrandom(libbuf, ((len*6)+7)/8);
// 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;
}
s[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;
}
// Read array of colon separated strings from file with given first entry
char **get_userline(char *filename, char *username)
{
FILE *fp = xfopen(filename, "r");
int len = strlen(username);
char *line = 0, **data;
size_t n = 0;
while (getline(&line, &n, fp)) {
if (!strncmp(line, username, len) && line[len]==':') {
data = xzalloc(10*sizeof(char *));
for (len = 0; len<9; len++) {
data[len] = line;
if (!(line = strchr(line, ':'))) break;
*line++ = 0;
}
return data;
}
memset(line, 0, strlen(line));
free(line);
line = 0;
n = 0;
}
return 0;
}
// update colon-separated text files ala /etc/{passwd,shadow,group,gshadow}
// returns 1 for success, 0 for failure
// username = string match for first entry in line
// entry = new entry (NULL deletes matching line, contains : adds/replaces line)
// pos = if no : in "entry", which field to replace (0 is first)
// filename+ = new copy being written, filename- = backup of old version
int update_password(char *filename, char *username, char *entry, int pos)
{
char *ff = xmprintf("%s-", filename), *line = 0, *start, *end, *out, *oo;
FILE *ofp;
int len = strlen(username)*!strchr(username,':'), rc = 0, ret = 0, found = 0,
nfd;
struct flock lock = {.l_type = F_WRLCK};
struct stat st;
long long ll = 0;
// Open old filename ("r" won't let us lock) and get blocking lock
if (!(ofp = fopen(filename, "w+")) || 0>fcntl(fileno(ofp), F_SETLK, &lock)\
|| fstat(fileno(ofp), &st))
{
perror_msg_raw(filename);
goto free_storage;
}
// Delete old backup, link new backup. (Failure here isn't fatal.)
unlink(ff);
if (0>link(filename, ff)) perror_msg_raw(ff);
// Open new file to copy entries to
ff[strlen(ff)-1] = '+';
if (-1 == (nfd = xcreate(ff, O_CREAT|O_EXCL|O_WRONLY, st.st_mode))) {
perror_msg_raw(ff);
goto free_storage;
}
// Loop through lines
for (; getline(&line, (void *)&ll, ofp)!=-1; memset(line, 0, strlen(line))) {
// find matching line
oo = 0;
start = end = chomp(line);
if (strncmp(line, username, len) || !(line[len] && line[len]!=':'))
out = line;
else {
found++;
// Delete or replace whole line?
if (!entry) out = 0;
else if (strchr(entry, ':')) out = entry;
// Replace entry at pos
else {
for (;; pos--, start = ++end) {
while (*end && *end != ':') end++;
if (!pos || !*end) break;
}
if (pos>=0) out = line;
else oo = out = xmprintf("%*s%s%s\n", (int)(start-line),line,entry,end);
}
}
if (out) {
rc = dprintf(nfd, "%s\n", out);
free(out);
if (rc<0) {
perror_msg_raw(ff);
goto free_storage;
}
free(oo);
}
}
free(line);
if (!found && entry && strchr(entry, ':')) dprintf(nfd, "%s\n", entry);
fsync(nfd);
close(nfd); // automatically unlocks
if (!found || rename(ff, filename)) {
if (found) perror_msg("%s -> %s", ff, filename);
else if (entry) error_msg("No %s in %s", username, filename);
} else ret = 1, *ff = 0;
free_storage:
if (ofp) fclose(ofp);
if (ff && *ff) unlink(ff);
free(ff);
return ret;
}
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