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#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 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 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 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();
}
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