1#include <pthread.h>
2#include <byteswap.h>
3#include <string.h>
4#include <unistd.h>
5#include "pwf.h"
6#include "nscd.h"
7
8static char *itoa(char *p, uint32_t x)
9{
10 // number of digits in a uint32_t + NUL
11 p += 11;
12 *--p = 0;
13 do {
14 *--p = '0' + x % 10;
15 x /= 10;
16 } while (x);
17 return p;
18}
19
20int __getpw_a(const char *name, uid_t uid, struct passwd *pw, char **buf, size_t *size, struct passwd **res)
21{
22 FILE *f;
23 int cs;
24 int rv = 0;
25
26 *res = 0;
27
28 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
29
30 f = fopen("/etc/passwd", "rbe");
31 if (!f) {
32 rv = errno;
33 goto done;
34 }
35
36 while (!(rv = __getpwent_a(f, pw, buf, size, res)) && *res) {
37 if (name && !strcmp(name, (*res)->pw_name)
38 || !name && (*res)->pw_uid == uid)
39 break;
40 }
41 fclose(f);
42
43 if (!*res && (rv == 0 || rv == ENOENT || rv == ENOTDIR)) {
44 int32_t req = name ? GETPWBYNAME : GETPWBYUID;
45 const char *key;
46 int32_t passwdbuf[PW_LEN] = {0};
47 size_t len = 0;
48 char uidbuf[11] = {0};
49
50 if (name) {
51 key = name;
52 } else {
53 /* uid outside of this range can't be queried with the
54 * nscd interface, but might happen if uid_t ever
55 * happens to be a larger type (this is not true as of
56 * now)
57 */
58 if(uid < 0 || uid > UINT32_MAX) {
59 rv = 0;
60 goto done;
61 }
62 key = itoa(uidbuf, uid);
63 }
64
65 f = __nscd_query(req, key, passwdbuf, sizeof passwdbuf, (int[]){0});
66 if (!f) { rv = errno; goto done; }
67
68 if(!passwdbuf[PWFOUND]) { rv = 0; goto cleanup_f; }
69
70 /* A zero length response from nscd is invalid. We ignore
71 * invalid responses and just report an error, rather than
72 * trying to do something with them.
73 */
74 if (!passwdbuf[PWNAMELEN] || !passwdbuf[PWPASSWDLEN]
75 || !passwdbuf[PWGECOSLEN] || !passwdbuf[PWDIRLEN]
76 || !passwdbuf[PWSHELLLEN]) {
77 rv = EIO;
78 goto cleanup_f;
79 }
80
81 if ((passwdbuf[PWNAMELEN]|passwdbuf[PWPASSWDLEN]
82 |passwdbuf[PWGECOSLEN]|passwdbuf[PWDIRLEN]
83 |passwdbuf[PWSHELLLEN]) >= SIZE_MAX/8) {
84 rv = ENOMEM;
85 goto cleanup_f;
86 }
87
88 len = passwdbuf[PWNAMELEN] + passwdbuf[PWPASSWDLEN]
89 + passwdbuf[PWGECOSLEN] + passwdbuf[PWDIRLEN]
90 + passwdbuf[PWSHELLLEN];
91
92 if (len > *size || !*buf) {
93 char *tmp = realloc(*buf, len);
94 if (!tmp) {
95 rv = errno;
96 goto cleanup_f;
97 }
98 *buf = tmp;
99 *size = len;
100 }
101
102 if (!fread(*buf, len, 1, f)) {
103 rv = ferror(f) ? errno : EIO;
104 goto cleanup_f;
105 }
106
107 pw->pw_name = *buf;
108 pw->pw_passwd = pw->pw_name + passwdbuf[PWNAMELEN];
109 pw->pw_gecos = pw->pw_passwd + passwdbuf[PWPASSWDLEN];
110 pw->pw_dir = pw->pw_gecos + passwdbuf[PWGECOSLEN];
111 pw->pw_shell = pw->pw_dir + passwdbuf[PWDIRLEN];
112 pw->pw_uid = passwdbuf[PWUID];
113 pw->pw_gid = passwdbuf[PWGID];
114
115 /* Don't assume that nscd made sure to null terminate strings.
116 * It's supposed to, but malicious nscd should be ignored
117 * rather than causing a crash.
118 */
119 if (pw->pw_passwd[-1] || pw->pw_gecos[-1] || pw->pw_dir[-1]
120 || pw->pw_shell[passwdbuf[PWSHELLLEN]-1]) {
121 rv = EIO;
122 goto cleanup_f;
123 }
124
125 if (name && strcmp(name, pw->pw_name)
126 || !name && uid != pw->pw_uid) {
127 rv = EIO;
128 goto cleanup_f;
129 }
130
131
132 *res = pw;
133cleanup_f:
134 fclose(f);
135 goto done;
136 }
137
138done:
139 pthread_setcancelstate(cs, 0);
140 if (rv) errno = rv;
141 return rv;
142}