1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
|
#include "util.h"
#define DEFAULT_SYSUSRTMP "/tmp/user"
#define CONFIG_FILE "/etc/security/tmpdir.conf"
/* Standard implementation of xrealloc -- exit if anything goes
wrong */
void *xrealloc(void *ptr, size_t size) {
void *r = realloc(ptr, size);
if (r == NULL) {
_log_err(LOG_ERR, "Out of memory in xrealloc");
exit(0);
}
return r;
}
/* Standard implementation of xmalloc -- exit if anything goes
wrong */
void *xmalloc(size_t size) {
void *r = malloc(size);
if (r == NULL) {
_log_err(LOG_ERR, "Out of memory in xmalloc");
exit(0);
}
return r;
}
/* Why doesn't libc have a method to read a line from a file, similar
to python's f.readline()? This is an implementation. */
char *freadline(FILE *stream) {
char buf[512];
size_t alloc = 0;
char *ret = NULL;
char *t;
t = fgets(buf, sizeof(buf), stream);
if (t == NULL) {
return NULL;
}
ret = xmalloc(sizeof(buf));
strcpy(ret, buf);
t = fgets(buf, sizeof(buf), stream);
return ret;
}
int check_dir_ok(char *path) {
struct stat statbuf;
int ret;
ret = lstat(path,&statbuf);
if (ret == -1) {
_log_err(LOG_NOTICE, "%s", "lstat %s failed: %s\n", path, strerror(errno));
return 1;
} else if (statbuf.st_uid != 0) {
/* Somebody else than root has grabbed the dir. Bad, bad, bad. */
_log_err(LOG_ERR, "%s is owned by uid %d instead of root "
"(uid 0).\n", path, statbuf.st_uid);
return 1;
} else if (!S_ISDIR(statbuf.st_mode)) {
_log_err(LOG_NOTICE, "%s is not a directory.\n", path);
return 1;
} else if ((statbuf.st_mode & S_IWGRP) || (statbuf.st_mode & S_IWOTH)) {
_log_err(LOG_NOTICE, "%s is group or world writable. ", path);
return 1;
}
return 0;
}
int check_path(const char *path) {
char *p = strdup(path);
char *tmp;
/* special-case /, since it should end with / */
if (check_dir_ok("/") != 0) {
free(p);
return 1;
}
tmp = strchr(p+1,'/'); /* +1 so we don't change the initial / :) */
if (tmp != NULL) {
*tmp = '\0';
}
while (tmp != NULL) {
if (check_dir_ok(p) != 0) {
free(p);
return 1;
}
*tmp = '/';
tmp = strchr(tmp+1,'/');
}
/* One last check for the full path */
if (check_dir_ok(p) != 0) {
free(p);
return 1;
}
free(p);
return 0;
}
char *get_tmp_dir() {
char *line;
FILE *conf;
char *confdir = dirname(strdup(CONFIG_FILE));
char *tmp;
/* Start paranoia checks */
if (check_path(confdir) != 0) {
/* Can't trust confdir, just return DEFAULT_SYSUSRTMP */
return strdup(DEFAULT_SYSUSRTMP);
}
/* Ok, paranoia checks over, let's open the file and parse it, then */
conf = fopen(CONFIG_FILE,"r");
if (conf == NULL) {
/* Fallback */
return strdup(DEFAULT_SYSUSRTMP);
}
line = freadline(conf);
while (line) {
char *key, *value;
if ((line[0] == '#') || (strchr(line, '=') == NULL)) {
free(line);
line = freadline(conf);
continue;
}
tmp = strchr(line, '=');
*tmp = '\0';
key = line;
value = tmp+1;
/* chomp */
if (value[strlen(value)-1] == '\n') {
value[strlen(value)-1] = '\0';
}
if (strcmp(key, "tmpdir") == 0) {
value = strdup(value);
free(line);
return value;
}
/* Cleanup */
free(line);
line = freadline(conf);
}
/* Fallback */
return strdup(DEFAULT_SYSUSRTMP);
}
/* some syslogging */
void _log_err(int err, const char *format, ...) {
va_list args;
va_start(args, format);
openlog("PAM_tmpdir", LOG_CONS|LOG_PID, LOG_AUTH);
vsyslog(err, format, args);
va_end(args);
closelog();
}
const char *get_homedir(pam_handle_t *pamh) {
const void *username;
struct passwd* user_entry;
int r;
r = pam_get_item(pamh, PAM_USER, &username);
if (r != PAM_SUCCESS) {
_log_err(LOG_WARNING, "could not get PAM user");
return NULL;
}
user_entry = getpwnam(username);
return user_entry->pw_dir;
}
|
