diff options
Diffstat (limited to 'src/exec_common.c')
| -rw-r--r-- | src/exec_common.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/src/exec_common.c b/src/exec_common.c new file mode 100644 index 0000000..c5d704f --- /dev/null +++ b/src/exec_common.c @@ -0,0 +1,136 @@ +/* + * 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); +} |