radare2/libr/util/sandbox.c
2019-07-09 10:49:05 +02:00

435 lines
8.8 KiB
C

/* radare - LGPL - Copyright 2012-2017 - pancake */
#include <r_util.h>
#include <signal.h>
#if _MSC_VER
#include <process.h> // to compile execl under msvc windows
#include <direct.h> // to compile chdir under msvc windows
#endif
#if HAVE_CAPSICUM
#include <sys/capsicum.h>
#endif
static bool enabled = false;
static bool disabled = false;
static bool inHomeWww(const char *path) {
bool ret = false;
char *homeWww = r_str_home (R2_HOME_WWWROOT R_SYS_DIR);
if (homeWww) {
if (!strncmp (path, homeWww, strlen (homeWww))) {
ret = true;
}
free (homeWww);
}
return ret;
}
/**
* This function verifies that the given path is allowed. Paths are allowed only if they don't
* contain .. components (which would indicate directory traversal) and they are relative.
* Paths pointing into the webroot are an exception: For reaching the webroot, .. and absolute
* path are ok.
*/
R_API bool r_sandbox_check_path (const char *path) {
size_t root_len;
char *p;
/* XXX: the sandbox can be bypassed if a directory is symlink */
if (!path) {
return false;
}
root_len = strlen (R2_LIBDIR"/radare2");
if (!strncmp (path, R2_LIBDIR"/radare2", root_len)) {
return true;
}
root_len = strlen (R2_DATDIR"/radare2");
if (!strncmp (path, R2_DATDIR"/radare2", root_len)) {
return true;
}
if (inHomeWww (path)) {
return true;
}
// Accessing stuff inside the webroot is ok even if we need .. or leading / for that
root_len = strlen (R2_WWWROOT);
if (R2_WWWROOT[0] && !strncmp (path, R2_WWWROOT, root_len) && (
R2_WWWROOT[root_len-1] == '/' || path[root_len] == '/' || path[root_len] == '\0')) {
path += strlen (R2_WWWROOT);
while (*path == '/') {
path++;
}
}
// ./ path is not allowed
if (path[0]=='.' && path[1]=='/') {
return false;
}
// Properly check for directory traversal using "..". First, does it start with a .. part?
if (path[0] == '.' && path[1] == '.' && (path[2] == '\0' || path[2] == '/')) {
return 0;
}
// Or does it have .. in some other position?
for (p = strstr (path, "/.."); p; p = strstr(p, "/..")) {
if (p[3] == '\0' || p[3] == '/') {
return false;
}
}
// Absolute paths are forbidden.
if (*path == '/') {
return false;
}
#if __UNIX__
char ch;
if (readlink (path, &ch, 1) != -1) {
return false;
}
#endif
return true;
}
R_API bool r_sandbox_disable (bool e) {
if (e) {
#if LIBC_HAVE_PLEDGE
if (enabled) {
eprintf ("sandbox mode couldn't be disabled when pledged\n");
return enabled;
}
#endif
#if HAVE_CAPSICUM
if (enabled) {
eprintf ("sandbox mode couldn't be disabled in capability mode\n");
return enabled;
}
#endif
disabled = enabled;
enabled = false;
} else {
enabled = disabled;
}
return enabled;
}
R_API bool r_sandbox_enable (bool e) {
if (enabled) {
if (!e) {
// eprintf ("Can't disable sandbox\n");
}
return true;
}
enabled = e;
#if LIBC_HAVE_PLEDGE
if (enabled && pledge ("stdio rpath tty prot_exec inet", NULL) == -1) {
eprintf ("sandbox: pledge call failed\n");
return false;
}
#endif
#if HAVE_CAPSICUM
if (enabled) {
#if __FreeBSD_version >= 1000000
cap_rights_t wrt, rdr;
if (!cap_rights_init (&wrt, CAP_READ, CAP_WRITE)) {
eprintf ("sandbox: write descriptor failed\n");
return false;
}
if (!cap_rights_init (&rdr, CAP_READ, CAP_EVENT, CAP_FCNTL)) {
eprintf ("sandbox: read descriptor failed\n");
return false;
}
if (cap_rights_limit (STDIN_FILENO, &rdr) == -1) {
eprintf ("sandbox: stdin protection failed\n");
return false;
}
if (cap_rights_limit (STDOUT_FILENO, &wrt) == -1) {
eprintf ("sandbox: stdout protection failed\n");
return false;
}
if (cap_rights_limit (STDERR_FILENO, &wrt) == -1) {
eprintf ("sandbox: stderr protection failed\n");
return false;
}
#endif
if (cap_enter () != 0) {
eprintf ("sandbox: call_enter failed\n");
return false;
}
}
#endif
return enabled;
}
R_API int r_sandbox_system (const char *x, int n) {
if (enabled) {
eprintf ("sandbox: system call disabled\n");
return -1;
}
#if LIBC_HAVE_FORK
#if LIBC_HAVE_SYSTEM
if (n) {
#if APPLE_SDK_IPHONEOS
#include <dlfcn.h>
int (*__system)(const char *cmd)
= dlsym (NULL, "system");
if (__system) {
return __system (x);
}
return -1;
#else
return system (x);
#endif
}
return execl ("/bin/sh", "sh", "-c", x, (const char*)NULL);
#else
#include <spawn.h>
if (n && !strchr (x, '|')) {
char **argv, *cmd = strdup (x);
int rc, pid, argc;
char *isbg = strchr (cmd, '&');
// XXX this is hacky
if (isbg) {
*isbg = 0;
}
argv = r_str_argv (cmd, &argc);
if (argv) {
char *argv0 = r_file_path (argv[0]);
if (!argv0) {
eprintf ("Cannot find '%s'\n", argv[0]);
return -1;
}
pid = 0;
posix_spawn (&pid, argv0, NULL, NULL, argv, NULL);
if (isbg) {
// XXX. wait for children
rc = 0;
} else {
rc = waitpid (pid, NULL, 0);
}
r_str_argv_free (argv);
free (argv0);
return rc;
}
eprintf ("Error parsing command arguments\n");
return -1;
}
int child = fork();
if (child == -1) return -1;
if (child) {
return waitpid (child, NULL, 0);
}
execl ("/bin/sh", "sh", "-c", x, (const char*)NULL);
exit (1);
#endif
#endif
return -1;
}
R_API bool r_sandbox_creat (const char *path, int mode) {
if (enabled) {
return false;
#if 0
if (mode & O_CREAT) return -1;
if (mode & O_RDWR) return -1;
if (!r_sandbox_check_path (path))
return -1;
#endif
}
int fd = open (path, O_CREAT | O_TRUNC | O_WRONLY, mode);
if (fd != -1) {
close (fd);
return true;
}
return false;
}
static char *expand_home(const char *p) {
if (*p == '~') {
return r_str_home (p);
}
return strdup (p);
}
R_API int r_sandbox_lseek(int fd, ut64 addr, int whence) {
if (enabled) {
return -1;
}
return lseek (fd, (off_t)addr, whence);
}
R_API int r_sandbox_truncate(int fd, ut64 length) {
if (enabled) {
return -1;
}
#ifdef _MSC_VER
return _chsize_s (fd, length);
#else
return ftruncate (fd, (off_t)length);
#endif
}
R_API int r_sandbox_read(int fd, ut8 *buf, int len) {
return enabled? -1: read (fd, buf, len);
}
R_API int r_sandbox_write(int fd, const ut8* buf, int len) {
return enabled? -1: write (fd, buf, len);
}
R_API int r_sandbox_close(int fd) {
return enabled? -1: close (fd);
}
/* perm <-> mode */
R_API int r_sandbox_open(const char *path, int mode, int perm) {
if (!path) {
return -1;
}
char *epath = expand_home (path);
int ret = -1;
#if __WINDOWS__
mode |= O_BINARY;
if (!strcmp (path, "/dev/null")) {
path = "NUL";
}
#endif
if (enabled) {
if ((mode & O_CREAT)
|| (mode & O_RDWR)
|| (!r_sandbox_check_path (epath))) {
free (epath);
return -1;
}
}
#if __WINDOWS__
{
wchar_t *wepath = r_utf8_to_utf16 (epath);
if (!wepath) {
free (epath);
return -1;
}
ret = _wopen (wepath, mode, perm);
free (wepath);
}
#else // __WINDOWS__
ret = open (epath, mode, perm);
#endif // __WINDOWS__
free (epath);
return ret;
}
R_API FILE *r_sandbox_fopen (const char *path, const char *mode) {
FILE *ret = NULL;
char *epath = NULL;
if (!path) {
return NULL;
}
if (enabled) {
if (strchr (mode, 'w') || strchr (mode, 'a') || strchr (mode, '+')) {
return NULL;
}
epath = expand_home (path);
if (!r_sandbox_check_path (epath)) {
free (epath);
return NULL;
}
}
if (!epath) {
epath = expand_home (path);
}
if ((strchr (mode, 'w') || r_file_is_regular (epath))) {
#if __WINDOWS__
wchar_t *wepath = r_utf8_to_utf16 (epath);
if (!wepath) {
free (epath);
return ret;
}
wchar_t *wmode = r_utf8_to_utf16 (mode);
if (!wmode) {
free (wepath);
free (epath);
return ret;
}
ret = _wfopen (wepath, wmode);
free (wmode);
free (wepath);
#else // __WINDOWS__
ret = fopen (epath, mode);
#endif // __WINDOWS__
}
free (epath);
return ret;
}
R_API int r_sandbox_chdir (const char *path) {
if (enabled) {
// TODO: check path
if (strstr (path, "../")) {
return -1;
}
if (*path == '/') {
return -1;
}
return -1;
}
return chdir (path);
}
R_API int r_sandbox_kill(int pid, int sig) {
// XXX: fine-tune. maybe we want to enable kill for child?
if (enabled) {
return -1;
}
#if __UNIX__
return kill (pid, sig);
#endif
return -1;
}
#if __WINDOWS__
R_API HANDLE r_sandbox_opendir (const char *path, WIN32_FIND_DATAW *entry) {
wchar_t dir[MAX_PATH];
wchar_t *wcpath = 0;
if (!path) {
return NULL;
}
if (r_sandbox_enable (0)) {
if (path && !r_sandbox_check_path (path)) {
return NULL;
}
}
if (!(wcpath = r_utf8_to_utf16 (path))) {
return NULL;
}
swprintf (dir, MAX_PATH, L"%ls\\*.*", wcpath);
free (wcpath);
return FindFirstFileW (dir, entry);
}
#else
R_API DIR* r_sandbox_opendir (const char *path) {
if (!path) {
return NULL;
}
if (r_sandbox_enable (0)) {
if (path && !r_sandbox_check_path (path)) {
return NULL;
}
}
return opendir (path);
}
#endif
R_API bool r_sys_stop () {
if (enabled) {
return false;
}
#if __UNIX__
return !r_sandbox_kill (0, SIGTSTP);
#else
return false;
#endif
}