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/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 1996, 1998-2005, 2010-2015, 2017-2019
* Todd C. Miller <Todd.Miller@sudo.ws>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Sponsored in part by the Defense Advanced Research Projects
* Agency (DARPA) and Air Force Research Laboratory, Air Force
* Materiel Command, USAF, under agreement number F39502-99-1-0512.
*/
/*
* This is an open source non-commercial project. Dear PVS-Studio, please check it.
* PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
*/
#include <config.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sudoers.h>
/*
* Check the given command against the specified allowlist (NULL-terminated).
* On success, rewrites cmnd based on the allowlist and returns true.
* On failure, returns false.
*/
static bool
cmnd_allowed(char *cmnd, size_t cmnd_size, struct stat *cmnd_sbp,
char * const *allowlist)
{
const char *cmnd_base;
char * const *al;
debug_decl(cmnd_allowed, SUDOERS_DEBUG_UTIL);
if (!sudo_goodpath(cmnd, cmnd_sbp))
debug_return_bool(false);
if (allowlist == NULL)
debug_return_bool(true); /* nothing to check */
/* We compare the base names to avoid excessive stat()ing. */
cmnd_base = sudo_basename(cmnd);
for (al = allowlist; *al != NULL; al++) {
const char *base, *path = *al;
struct stat sb;
base = sudo_basename(path);
if (strcmp(cmnd_base, base) != 0)
continue;
if (sudo_goodpath(path, &sb) &&
sb.st_dev == cmnd_sbp->st_dev && sb.st_ino == cmnd_sbp->st_ino) {
/* Overwrite cmnd with safe version from allowlist. */
if (strlcpy(cmnd, path, cmnd_size) < cmnd_size)
debug_return_bool(true);
}
}
debug_return_bool(false);
}
/*
* This function finds the full pathname for a command and stores it
* in a statically allocated array, filling in a pointer to the array.
* Returns FOUND if the command was found, NOT_FOUND if it was not found,
* NOT_FOUND_DOT if it would have been found but it is in '.' and
* ignore_dot is set or NOT_FOUND_ERROR if an error occurred.
* The caller is responsible for freeing the output file.
*/
int
find_path(const char *infile, char **outfile, struct stat *sbp,
const char *path, bool ignore_dot, char * const *allowlist)
{
char command[PATH_MAX];
const char *cp, *ep, *pathend;
bool found = false;
bool checkdot = false;
int len;
debug_decl(find_path, SUDOERS_DEBUG_UTIL);
sudo_debug_printf(SUDO_DEBUG_INFO|SUDO_DEBUG_LINENO,
"resolving %s", infile);
/*
* If we were given a fully qualified or relative path
* there is no need to look at $PATH.
*/
if (strchr(infile, '/') != NULL) {
if (strlcpy(command, infile, sizeof(command)) >= sizeof(command)) {
errno = ENAMETOOLONG;
debug_return_int(NOT_FOUND_ERROR);
}
found = cmnd_allowed(command, sizeof(command), sbp, allowlist);
goto done;
}
if (path == NULL)
debug_return_int(NOT_FOUND);
pathend = path + strlen(path);
for (cp = sudo_strsplit(path, pathend, ":", &ep); cp != NULL;
cp = sudo_strsplit(NULL, pathend, ":", &ep)) {
/*
* Search current dir last if it is in PATH.
* This will miss sneaky things like using './' or './/' (XXX)
*/
if (cp == ep || (*cp == '.' && cp + 1 == ep)) {
checkdot = 1;
continue;
}
/*
* Resolve the path and exit the loop if found.
*/
len = snprintf(command, sizeof(command), "%.*s/%s",
(int)(ep - cp), cp, infile);
if (len < 0 || len >= ssizeof(command)) {
errno = ENAMETOOLONG;
debug_return_int(NOT_FOUND_ERROR);
}
found = cmnd_allowed(command, sizeof(command), sbp, allowlist);
if (found)
break;
}
/*
* Check current dir if dot was in the PATH
*/
if (!found && checkdot) {
len = snprintf(command, sizeof(command), "./%s", infile);
if (len < 0 || len >= ssizeof(command)) {
errno = ENAMETOOLONG;
debug_return_int(NOT_FOUND_ERROR);
}
found = cmnd_allowed(command, sizeof(command), sbp, allowlist);
if (found && ignore_dot)
debug_return_int(NOT_FOUND_DOT);
}
done:
if (found) {
sudo_debug_printf(SUDO_DEBUG_INFO|SUDO_DEBUG_LINENO,
"found %s", command);
if ((*outfile = strdup(command)) == NULL)
debug_return_int(NOT_FOUND_ERROR);
debug_return_int(FOUND);
}
debug_return_int(NOT_FOUND);
}
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