[337] | 1 | #include <fcntl.h>
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| 2 | #include <unistd.h>
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| 3 | #include <sys/stat.h>
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| 4 | #include <ctype.h>
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| 5 | #include <pthread.h>
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| 6 | #include "pwf.h"
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| 7 |
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| 8 | /* This implementation support Openwall-style TCB passwords in place of
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| 9 | * traditional shadow, if the appropriate directories and files exist.
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| 10 | * Thus, it is careful to avoid following symlinks or blocking on fifos
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| 11 | * which a malicious user might create in place of his or her TCB shadow
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| 12 | * file. It also avoids any allocation to prevent memory-exhaustion
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| 13 | * attacks via huge TCB shadow files. */
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| 14 |
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| 15 | static long xatol(char **s)
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| 16 | {
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| 17 | long x;
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| 18 | if (**s == ':' || **s == '\n') return -1;
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| 19 | for (x=0; **s-'0'<10U; ++*s) x=10*x+(**s-'0');
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| 20 | return x;
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| 21 | }
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| 22 |
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| 23 | int __parsespent(char *s, struct spwd *sp)
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| 24 | {
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| 25 | sp->sp_namp = s;
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| 26 | if (!(s = strchr(s, ':'))) return -1;
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| 27 | *s = 0;
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| 28 |
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| 29 | sp->sp_pwdp = ++s;
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| 30 | if (!(s = strchr(s, ':'))) return -1;
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| 31 | *s = 0;
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| 32 |
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| 33 | s++; sp->sp_lstchg = xatol(&s);
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| 34 | if (*s != ':') return -1;
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| 35 |
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| 36 | s++; sp->sp_min = xatol(&s);
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| 37 | if (*s != ':') return -1;
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| 38 |
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| 39 | s++; sp->sp_max = xatol(&s);
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| 40 | if (*s != ':') return -1;
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| 41 |
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| 42 | s++; sp->sp_warn = xatol(&s);
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| 43 | if (*s != ':') return -1;
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| 44 |
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| 45 | s++; sp->sp_inact = xatol(&s);
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| 46 | if (*s != ':') return -1;
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| 47 |
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| 48 | s++; sp->sp_expire = xatol(&s);
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| 49 | if (*s != ':') return -1;
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| 50 |
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| 51 | s++; sp->sp_flag = xatol(&s);
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| 52 | if (*s != '\n') return -1;
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| 53 | return 0;
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| 54 | }
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| 55 |
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| 56 | static void cleanup(void *p)
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| 57 | {
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| 58 | fclose(p);
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| 59 | }
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| 60 |
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| 61 | int getspnam_r(const char *name, struct spwd *sp, char *buf, size_t size, struct spwd **res)
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| 62 | {
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| 63 | char path[20+NAME_MAX];
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| 64 | FILE *f = 0;
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| 65 | int rv = 0;
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| 66 | int fd;
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| 67 | size_t k, l = strlen(name);
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| 68 | int skip = 0;
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| 69 | int cs;
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| 70 |
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| 71 | *res = 0;
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| 72 |
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| 73 | /* Disallow potentially-malicious user names */
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| 74 | if (*name=='.' || strchr(name, '/') || !l)
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| 75 | return errno = EINVAL;
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| 76 |
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| 77 | /* Buffer size must at least be able to hold name, plus some.. */
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| 78 | if (size < l+100)
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| 79 | return errno = ERANGE;
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| 80 |
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| 81 | /* Protect against truncation */
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| 82 | if (snprintf(path, sizeof path, "/etc/tcb/%s/shadow", name) >= sizeof path)
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| 83 | return errno = EINVAL;
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| 84 |
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| 85 | fd = open(path, O_RDONLY|O_NOFOLLOW|O_NONBLOCK|O_CLOEXEC);
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| 86 | if (fd >= 0) {
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| 87 | struct stat st = { 0 };
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| 88 | errno = EINVAL;
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| 89 | if (fstat(fd, &st) || !S_ISREG(st.st_mode) || !(f = fdopen(fd, "rb"))) {
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| 90 | pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
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| 91 | close(fd);
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| 92 | pthread_setcancelstate(cs, 0);
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| 93 | return errno;
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| 94 | }
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| 95 | } else {
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| 96 | f = fopen("/etc/shadow", "rbe");
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| 97 | if (!f) return errno;
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| 98 | }
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| 99 |
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| 100 | pthread_cleanup_push(cleanup, f);
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| 101 | while (fgets(buf, size, f) && (k=strlen(buf))>0) {
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| 102 | if (skip || strncmp(name, buf, l) || buf[l]!=':') {
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| 103 | skip = buf[k-1] != '\n';
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| 104 | continue;
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| 105 | }
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| 106 | if (buf[k-1] != '\n') {
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| 107 | rv = ERANGE;
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| 108 | break;
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| 109 | }
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| 110 |
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| 111 | if (__parsespent(buf, sp) < 0) continue;
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| 112 | *res = sp;
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| 113 | break;
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| 114 | }
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| 115 | pthread_cleanup_pop(1);
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| 116 | if (rv) errno = rv;
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| 117 | return rv;
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| 118 | }
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