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| | #include <pthread.h>
#include <byteswap.h>
#include <string.h>
#include <unistd.h>
#include "pwf.h"
#include "nscd.h"
static char *itoa(char *p, uint32_t x)
{
// number of digits in a uint32_t + NUL
p += 11;
*--p = 0;
do {
*--p = '0' + x % 10;
x /= 10;
} while (x);
return p;
}
int __getpw_a(const char *name, uid_t uid, struct passwd *pw, char **buf, size_t *size, struct passwd **res)
{
FILE *f;
int cs;
int rv = 0;
*res = 0;
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
f = fopen("/etc/passwd", "rbe");
if (!f) {
rv = errno;
goto done;
}
while (!(rv = __getpwent_a(f, pw, buf, size, res)) && *res) {
if (name && !strcmp(name, (*res)->pw_name)
|| !name && (*res)->pw_uid == uid)
break;
}
fclose(f);
if (!*res && (rv == 0 || rv == ENOENT || rv == ENOTDIR)) {
int32_t req = name ? GETPWBYNAME : GETPWBYUID;
const char *key;
int32_t passwdbuf[PW_LEN] = {0};
size_t len = 0;
char uidbuf[11] = {0};
if (name) {
key = name;
} else {
/* uid outside of this range can't be queried with the
* nscd interface, but might happen if uid_t ever
* happens to be a larger type (this is not true as of
* now)
*/
if(uid < 0 || uid > UINT32_MAX) {
rv = 0;
goto done;
}
key = itoa(uidbuf, uid);
}
f = __nscd_query(req, key, passwdbuf, sizeof passwdbuf, (int[]){0});
if (!f) { rv = errno; goto done; }
if(!passwdbuf[PWFOUND] || passwdbuf[PWFOUND] == -1) { rv = 0; goto cleanup_f; }
/* A zero length response from nscd is invalid. We ignore
* invalid responses and just report an error, rather than
* trying to do something with them.
*/
if (!passwdbuf[PWNAMELEN] || !passwdbuf[PWPASSWDLEN]
|| !passwdbuf[PWGECOSLEN] || !passwdbuf[PWDIRLEN]
|| !passwdbuf[PWSHELLLEN]) {
rv = EIO;
goto cleanup_f;
}
if ((passwdbuf[PWNAMELEN]|passwdbuf[PWPASSWDLEN]
|passwdbuf[PWGECOSLEN]|passwdbuf[PWDIRLEN]
|passwdbuf[PWSHELLLEN]) >= SIZE_MAX/8) {
rv = ENOMEM;
goto cleanup_f;
}
len = passwdbuf[PWNAMELEN] + passwdbuf[PWPASSWDLEN]
+ passwdbuf[PWGECOSLEN] + passwdbuf[PWDIRLEN]
+ passwdbuf[PWSHELLLEN];
if (len > *size || !*buf) {
char *tmp = realloc(*buf, len);
if (!tmp) {
rv = errno;
goto cleanup_f;
}
*buf = tmp;
*size = len;
}
if (!fread(*buf, len, 1, f)) {
rv = ferror(f) ? errno : EIO;
goto cleanup_f;
}
pw->pw_name = *buf;
pw->pw_passwd = pw->pw_name + passwdbuf[PWNAMELEN];
pw->pw_gecos = pw->pw_passwd + passwdbuf[PWPASSWDLEN];
pw->pw_dir = pw->pw_gecos + passwdbuf[PWGECOSLEN];
pw->pw_shell = pw->pw_dir + passwdbuf[PWDIRLEN];
pw->pw_uid = passwdbuf[PWUID];
pw->pw_gid = passwdbuf[PWGID];
/* Don't assume that nscd made sure to null terminate strings.
* It's supposed to, but malicious nscd should be ignored
* rather than causing a crash.
*/
if (pw->pw_passwd[-1] || pw->pw_gecos[-1] || pw->pw_dir[-1]
|| pw->pw_shell[passwdbuf[PWSHELLLEN]-1]) {
rv = EIO;
goto cleanup_f;
}
if (name && strcmp(name, pw->pw_name)
|| !name && uid != pw->pw_uid) {
rv = EIO;
goto cleanup_f;
}
*res = pw;
cleanup_f:
fclose(f);
goto done;
}
done:
pthread_setcancelstate(cs, 0);
if (rv) errno = rv;
return rv;
}
|