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/*
* Placed in the public domain
*/
/* $OpenBSD: modpipe.c,v 1.6 2013/11/21 03:16:47 djm Exp $ */
#include "includes.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <stdlib.h>
#include <errno.h>
#include <pwd.h>
#ifdef HAVE_LIBGEN_H
#include <libgen.h>
#endif
static void
fatal(const char *fmt, ...)
{
va_list args;
va_start(args, fmt);
vfprintf(stderr, fmt, args);
fputc('\n', stderr);
va_end(args);
exit(1);
}
/* Based on session.c. NB. keep tests in sync */
static void
safely_chroot(const char *path, uid_t uid)
{
const char *cp;
char component[PATH_MAX];
struct stat st;
if (*path != '/')
fatal("chroot path does not begin at root");
if (strlen(path) >= sizeof(component))
fatal("chroot path too long");
/*
* Descend the path, checking that each component is a
* root-owned directory with strict permissions.
*/
for (cp = path; cp != NULL;) {
if ((cp = strchr(cp, '/')) == NULL)
strlcpy(component, path, sizeof(component));
else {
cp++;
memcpy(component, path, cp - path);
component[cp - path] = '\0';
}
/* debug3("%s: checking '%s'", __func__, component); */
if (stat(component, &st) != 0)
fatal("%s: stat(\"%s\"): %s", __func__,
component, strerror(errno));
if (st.st_uid != 0 || (st.st_mode & 022) != 0)
fatal("bad ownership or modes for chroot "
"directory %s\"%s\"",
cp == NULL ? "" : "component ", component);
if (!S_ISDIR(st.st_mode))
fatal("chroot path %s\"%s\" is not a directory",
cp == NULL ? "" : "component ", component);
}
if (chdir(path) == -1)
fatal("Unable to chdir to chroot path \"%s\": "
"%s", path, strerror(errno));
}
/* from platform.c */
int
platform_sys_dir_uid(uid_t uid)
{
if (uid == 0)
return 1;
#ifdef PLATFORM_SYS_DIR_UID
if (uid == PLATFORM_SYS_DIR_UID)
return 1;
#endif
return 0;
}
/* from auth.c */
int
auth_secure_path(const char *name, struct stat *stp, const char *pw_dir,
uid_t uid, char *err, size_t errlen)
{
char buf[PATH_MAX], homedir[PATH_MAX];
char *cp;
int comparehome = 0;
struct stat st;
if (realpath(name, buf) == NULL) {
snprintf(err, errlen, "realpath %s failed: %s", name,
strerror(errno));
return -1;
}
if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL)
comparehome = 1;
if (!S_ISREG(stp->st_mode)) {
snprintf(err, errlen, "%s is not a regular file", buf);
return -1;
}
if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) ||
(stp->st_mode & 022) != 0) {
snprintf(err, errlen, "bad ownership or modes for file %s",
buf);
return -1;
}
/* for each component of the canonical path, walking upwards */
for (;;) {
if ((cp = dirname(buf)) == NULL) {
snprintf(err, errlen, "dirname() failed");
return -1;
}
strlcpy(buf, cp, sizeof(buf));
if (stat(buf, &st) < 0 ||
(!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) ||
(st.st_mode & 022) != 0) {
snprintf(err, errlen,
"bad ownership or modes for directory %s", buf);
return -1;
}
/* If are past the homedir then we can stop */
if (comparehome && strcmp(homedir, buf) == 0)
break;
/*
* dirname should always complete with a "/" path,
* but we can be paranoid and check for "." too
*/
if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
break;
}
return 0;
}
static void
usage(void)
{
fprintf(stderr, "check-perm -m [chroot | keys-command] [path]\n");
exit(1);
}
int
main(int argc, char **argv)
{
const char *path = ".";
char errmsg[256];
int ch, mode = -1;
extern char *optarg;
extern int optind;
struct stat st;
while ((ch = getopt(argc, argv, "hm:")) != -1) {
switch (ch) {
case 'm':
if (strcasecmp(optarg, "chroot") == 0)
mode = 1;
else if (strcasecmp(optarg, "keys-command") == 0)
mode = 2;
else {
fprintf(stderr, "Invalid -m option\n"),
usage();
}
break;
default:
usage();
}
}
argc -= optind;
argv += optind;
if (argc > 1)
usage();
else if (argc == 1)
path = argv[0];
if (mode == 1)
safely_chroot(path, getuid());
else if (mode == 2) {
if (stat(path, &st) < 0)
fatal("Could not stat %s: %s", path, strerror(errno));
if (auth_secure_path(path, &st, NULL, 0,
errmsg, sizeof(errmsg)) != 0)
fatal("Unsafe %s: %s", path, errmsg);
} else {
fprintf(stderr, "Invalid mode\n");
usage();
}
return 0;
}
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