1#include <fcntl.h>
2#include <unistd.h>
3#include <sys/stat.h>
4#include <ctype.h>
5#include <pthread.h>
6#include "pwf.h"
7
8/* This implementation support Openwall-style TCB passwords in place of
9 * traditional shadow, if the appropriate directories and files exist.
10 * Thus, it is careful to avoid following symlinks or blocking on fifos
11 * which a malicious user might create in place of his or her TCB shadow
12 * file. It also avoids any allocation to prevent memory-exhaustion
13 * attacks via huge TCB shadow files. */
14
15static long xatol(char **s)
16{
17 long x;
18 if (**s == ':' || **s == '\n') return -1;
19 for (x=0; **s-'0'<10U; ++*s) x=10*x+(**s-'0');
20 return x;
21}
22
23int __parsespent(char *s, struct spwd *sp)
24{
25 sp->sp_namp = s;
26 if (!(s = strchr(s, ':'))) return -1;
27 *s = 0;
28
29 sp->sp_pwdp = ++s;
30 if (!(s = strchr(s, ':'))) return -1;
31 *s = 0;
32
33 s++; sp->sp_lstchg = xatol(&s);
34 if (*s != ':') return -1;
35
36 s++; sp->sp_min = xatol(&s);
37 if (*s != ':') return -1;
38
39 s++; sp->sp_max = xatol(&s);
40 if (*s != ':') return -1;
41
42 s++; sp->sp_warn = xatol(&s);
43 if (*s != ':') return -1;
44
45 s++; sp->sp_inact = xatol(&s);
46 if (*s != ':') return -1;
47
48 s++; sp->sp_expire = xatol(&s);
49 if (*s != ':') return -1;
50
51 s++; sp->sp_flag = xatol(&s);
52 if (*s != '\n') return -1;
53 return 0;
54}
55
56static void cleanup(void *p)
57{
58 fclose(p);
59}
60
61int getspnam_r(const char *name, struct spwd *sp, char *buf, size_t size, struct spwd **res)
62{
63 char path[20+NAME_MAX];
64 FILE *f = 0;
65 int rv = 0;
66 int fd;
67 size_t k, l = strlen(name);
68 int skip = 0;
69 int cs;
70 int orig_errno = errno;
71
72 *res = 0;
73
74 /* Disallow potentially-malicious user names */
75 if (*name=='.' || strchr(name, '/') || !l)
76 return errno = EINVAL;
77
78 /* Buffer size must at least be able to hold name, plus some.. */
79 if (size < l+100)
80 return errno = ERANGE;
81
82 /* Protect against truncation */
83 if (snprintf(path, sizeof path, "/etc/tcb/%s/shadow", name) >= sizeof path)
84 return errno = EINVAL;
85
86 fd = open(path, O_RDONLY|O_NOFOLLOW|O_NONBLOCK|O_CLOEXEC);
87 if (fd >= 0) {
88 struct stat st = { 0 };
89 errno = EINVAL;
90 if (fstat(fd, &st) || !S_ISREG(st.st_mode) || !(f = fdopen(fd, "rb"))) {
91 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
92 close(fd);
93 pthread_setcancelstate(cs, 0);
94 return errno;
95 }
96 } else {
97 if (errno != ENOENT && errno != ENOTDIR)
98 return errno;
99 f = fopen("/etc/shadow", "rbe");
100 if (!f) {
101 if (errno != ENOENT && errno != ENOTDIR)
102 return errno;
103 return 0;
104 }
105 }
106
107 pthread_cleanup_push(cleanup, f);
108 while (fgets(buf, size, f) && (k=strlen(buf))>0) {
109 if (skip || strncmp(name, buf, l) || buf[l]!=':') {
110 skip = buf[k-1] != '\n';
111 continue;
112 }
113 if (buf[k-1] != '\n') {
114 rv = ERANGE;
115 break;
116 }
117
118 if (__parsespent(buf, sp) < 0) continue;
119 *res = sp;
120 break;
121 }
122 pthread_cleanup_pop(1);
123 errno = rv ? rv : orig_errno;
124 return rv;
125}