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/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2009-2022 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.
*/
/*
* 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 <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifdef HAVE_PRIV_SET
# include <priv.h>
#endif
#include <errno.h>
#include "sudo.h"
#include "sudo_exec.h"
/*
* Disable execution of child processes in the command we are about
* to run. On systems with privilege sets, we can remove the exec
* privilege. On other systems we use LD_PRELOAD and the like.
*/
char **
disable_execute(char *envp[], const char *dso)
{
debug_decl(disable_execute, SUDO_DEBUG_UTIL);
#ifdef HAVE_PRIV_SET
/* Solaris privileges, remove PRIV_PROC_EXEC post-execve. */
(void)priv_set(PRIV_ON, PRIV_INHERITABLE, "PRIV_FILE_DAC_READ", NULL);
(void)priv_set(PRIV_ON, PRIV_INHERITABLE, "PRIV_FILE_DAC_WRITE", NULL);
(void)priv_set(PRIV_ON, PRIV_INHERITABLE, "PRIV_FILE_DAC_SEARCH", NULL);
if (priv_set(PRIV_OFF, PRIV_LIMIT, "PRIV_PROC_EXEC", NULL) == 0)
debug_return_ptr(envp);
sudo_warn("%s", U_("unable to remove PRIV_PROC_EXEC from PRIV_LIMIT"));
#endif /* HAVE_PRIV_SET */
#ifdef RTLD_PRELOAD_VAR
if (dso != NULL)
envp = sudo_preload_dso(envp, dso, -1);
#endif /* RTLD_PRELOAD_VAR */
debug_return_ptr(envp);
}
/*
* Trap execution of child processes in the command we are about to run.
* Uses LD_PRELOAD and the like to perform a policy check on child commands.
*/
static char **
enable_intercept(char *envp[], const char *dso, int intercept_fd)
{
debug_decl(enable_intercept, SUDO_DEBUG_UTIL);
if (dso != NULL) {
#ifdef RTLD_PRELOAD_VAR
if (intercept_fd == -1)
sudo_fatalx("%s: no intercept fd", __func__);
envp = sudo_preload_dso(envp, dso, intercept_fd);
#else
/* Intercept not supported, envp unchanged. */
if (intercept_fd != -1)
close(intercept_fd);
#endif /* RTLD_PRELOAD_VAR */
}
debug_return_ptr(envp);
}
/*
* Like execve(2) but falls back to running through /bin/sh
* ala execvp(3) if we get ENOEXEC.
*/
int
sudo_execve(int fd, const char *path, char *const argv[], char *envp[],
int intercept_fd, int flags)
{
debug_decl(sudo_execve, SUDO_DEBUG_UTIL);
sudo_debug_execve(SUDO_DEBUG_INFO, path, argv, envp);
/* Modify the environment as needed to trap execve(). */
if (ISSET(flags, CD_NOEXEC))
envp = disable_execute(envp, sudo_conf_noexec_path());
if (ISSET(flags, CD_INTERCEPT|CD_LOG_SUBCMDS)) {
if (!ISSET(flags, CD_USE_PTRACE)) {
envp = enable_intercept(envp, sudo_conf_intercept_path(),
intercept_fd);
}
}
#ifdef HAVE_FEXECVE
if (fd != -1)
fexecve(fd, argv, envp);
else
#endif
execve(path, argv, envp);
if (fd == -1 && errno == ENOEXEC) {
int argc;
const char **nargv;
for (argc = 0; argv[argc] != NULL; argc++)
continue;
nargv = reallocarray(NULL, argc + 2, sizeof(char *));
if (nargv != NULL) {
nargv[0] = "sh";
nargv[1] = path;
memcpy(nargv + 2, argv + 1, argc * sizeof(char *));
execve(_PATH_SUDO_BSHELL, (char **)nargv, envp);
free(nargv);
}
}
debug_return_int(-1);
}
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