diff options
Diffstat (limited to 'plugins/sudoers/env.c')
| -rw-r--r-- | plugins/sudoers/env.c | 1419 |
1 files changed, 1419 insertions, 0 deletions
diff --git a/plugins/sudoers/env.c b/plugins/sudoers/env.c new file mode 100644 index 0000000..73f017a --- /dev/null +++ b/plugins/sudoers/env.c @@ -0,0 +1,1419 @@ +/* + * SPDX-License-Identifier: ISC + * + * Copyright (c) 2000-2005, 2007-2019 + * 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 <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#if defined(HAVE_STDINT_H) +# include <stdint.h> +#elif defined(HAVE_INTTYPES_H) +# include <inttypes.h> +#endif +#ifdef HAVE_LOGIN_CAP_H +# include <login_cap.h> +# ifndef LOGIN_SETENV +# define LOGIN_SETENV 0 +# endif +#endif /* HAVE_LOGIN_CAP_H */ +#include <ctype.h> +#include <errno.h> +#include <limits.h> +#include <pwd.h> + +#include "sudoers.h" + +/* + * Flags used in rebuild_env() + */ +#undef DID_TERM +#define DID_TERM 0x00000001 +#undef DID_PATH +#define DID_PATH 0x00000002 +#undef DID_HOME +#define DID_HOME 0x00000004 +#undef DID_SHELL +#define DID_SHELL 0x00000008 +#undef DID_LOGNAME +#define DID_LOGNAME 0x00000010 +#undef DID_USER +#define DID_USER 0x00000020 +#undef DID_LOGIN +#define DID_LOGIN 0x00000040 +#undef DID_MAIL +#define DID_MAIL 0x00000080 +#undef DID_MAX +#define DID_MAX 0x0000ffff + +#undef KEPT_TERM +#define KEPT_TERM 0x00010000 +#undef KEPT_PATH +#define KEPT_PATH 0x00020000 +#undef KEPT_HOME +#define KEPT_HOME 0x00040000 +#undef KEPT_SHELL +#define KEPT_SHELL 0x00080000 +#undef KEPT_LOGNAME +#define KEPT_LOGNAME 0x00100000 +#undef KEPT_USER +#define KEPT_USER 0x00200000 +#undef KEPT_LOGIN +#define KEPT_LOGIN 0x00400000 +#undef KEPT_MAIL +#define KEPT_MAIL 0x00800000 +#undef KEPT_MAX +#define KEPT_MAX 0xffff0000 + +/* + * AIX sets the LOGIN environment variable too. + */ +#ifdef _AIX +# define KEPT_USER_VARIABLES (KEPT_LOGIN|KEPT_LOGNAME|KEPT_USER) +#else +# define KEPT_USER_VARIABLES (KEPT_LOGNAME|KEPT_USER) +#endif + +/* + * Functions to open, close and parse an environment file, either + * a system file such as /etc/environment or one specified in sudoers. + */ +struct sudoers_env_file { + void * (*open)(const char *); + void (*close)(void *); + char * (*next)(void *, int *); +}; + +/* + * State for a local environment file. + */ +struct env_file_local { + FILE *fp; + char *line; + size_t linesize; +}; + +struct environment { + char **envp; /* pointer to the new environment */ + char **old_envp; /* pointer the old environment we allocated */ + size_t env_size; /* size of new_environ in char **'s */ + size_t env_len; /* number of slots used, not counting NULL */ +}; + +/* + * Copy of the sudo-managed environment. + */ +static struct environment env; + +/* + * Default table of "bad" variables to remove from the environment. + * XXX - how to omit TERMCAP if it starts with '/'? + */ +static const char *initial_badenv_table[] = { + "IFS", + "CDPATH", + "LOCALDOMAIN", + "RES_OPTIONS", + "HOSTALIASES", + "NLSPATH", + "PATH_LOCALE", + "LD_*", + "_RLD*", +#ifdef __hpux + "SHLIB_PATH", +#endif /* __hpux */ +#ifdef _AIX + "LDR_*", + "LIBPATH", + "AUTHSTATE", +#endif +#ifdef __APPLE__ + "DYLD_*", +#endif +#ifdef HAVE_KERB5 + "KRB5_CONFIG*", + "KRB5_KTNAME", +#endif /* HAVE_KERB5 */ +#ifdef HAVE_SECURID + "VAR_ACE", + "USR_ACE", + "DLC_ACE", +#endif /* HAVE_SECURID */ + "TERMINFO", /* terminfo, exclusive path to terminfo files */ + "TERMINFO_DIRS", /* terminfo, path(s) to terminfo files */ + "TERMPATH", /* termcap, path(s) to termcap files */ + "TERMCAP", /* XXX - only if it starts with '/' */ + "ENV", /* ksh, file to source before script runs */ + "BASH_ENV", /* bash, file to source before script runs */ + "PS4", /* bash, prefix for lines in xtrace mode */ + "GLOBIGNORE", /* bash, globbing patterns to ignore */ + "BASHOPTS", /* bash, initial "shopt -s" options */ + "SHELLOPTS", /* bash, initial "set -o" options */ + "JAVA_TOOL_OPTIONS", /* java, extra command line options */ + "PERLIO_DEBUG", /* perl, debugging output file */ + "PERLLIB", /* perl, search path for modules/includes */ + "PERL5LIB", /* perl 5, search path for modules/includes */ + "PERL5OPT", /* perl 5, extra command line options */ + "PERL5DB", /* perl 5, command used to load debugger */ + "FPATH", /* ksh, search path for functions */ + "NULLCMD", /* zsh, command for null file redirection */ + "READNULLCMD", /* zsh, command for null file redirection */ + "ZDOTDIR", /* zsh, search path for dot files */ + "TMPPREFIX", /* zsh, prefix for temporary files */ + "PYTHONHOME", /* python, module search path */ + "PYTHONPATH", /* python, search path */ + "PYTHONINSPECT", /* python, allow inspection */ + "PYTHONUSERBASE", /* python, per user site-packages directory */ + "RUBYLIB", /* ruby, library load path */ + "RUBYOPT", /* ruby, extra command line options */ + "*=()*", /* bash functions */ + NULL +}; + +/* + * Default table of variables to check for '%' and '/' characters. + */ +static const char *initial_checkenv_table[] = { + "COLORTERM", + "LANG", + "LANGUAGE", + "LC_*", + "LINGUAS", + "TERM", + "TZ", + NULL +}; + +/* + * Default table of variables to preserve in the environment. + */ +static const char *initial_keepenv_table[] = { + "COLORS", + "DISPLAY", + "HOSTNAME", + "KRB5CCNAME", + "LS_COLORS", + "PATH", + "PS1", + "PS2", + "XAUTHORITY", + "XAUTHORIZATION", + "XDG_CURRENT_DESKTOP", + NULL +}; + +/* + * Initialize env based on envp. + */ +bool +env_init(char * const envp[]) +{ + char * const *ep; + size_t len; + debug_decl(env_init, SUDOERS_DEBUG_ENV); + + if (envp == NULL) { + /* Free the old envp we allocated, if any. */ + sudoers_gc_remove(GC_PTR, env.old_envp); + free(env.old_envp); + + /* Reset to initial state but keep a pointer to what we allocated. */ + env.old_envp = env.envp; + env.envp = NULL; + env.env_size = 0; + env.env_len = 0; + } else { + /* Make private copy of envp. */ + for (ep = envp; *ep != NULL; ep++) + continue; + len = (size_t)(ep - envp); + + env.env_len = len; + env.env_size = len + 1 + 128; + env.envp = reallocarray(NULL, env.env_size, sizeof(char *)); + if (env.envp == NULL) { + env.env_size = 0; + env.env_len = 0; + sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory")); + debug_return_bool(false); + } + sudoers_gc_add(GC_PTR, env.envp); +#ifdef ENV_DEBUG + memset(env.envp, 0, env.env_size * sizeof(char *)); +#endif + memcpy(env.envp, envp, len * sizeof(char *)); + env.envp[len] = NULL; + + /* Free the old envp we allocated, if any. */ + sudoers_gc_remove(GC_PTR, env.old_envp); + free(env.old_envp); + env.old_envp = NULL; + } + + debug_return_bool(true); +} + +/* + * Getter for private copy of the environment. + */ +char ** +env_get(void) +{ + return env.envp; +} + +/* + * Swap the old and new copies of the environment. + */ +bool +env_swap_old(void) +{ + char **old_envp; + + if (env.old_envp == NULL) + return false; + old_envp = env.old_envp; + env.old_envp = env.envp; + env.envp = old_envp; + return true; +} + +/* + * Similar to putenv(3) but operates on sudo's private copy of the + * environment (not environ) and it always overwrites. The dupcheck param + * determines whether we need to verify that the variable is not already set. + * Will only overwrite an existing variable if overwrite is set. + * Does not include warnings or debugging to avoid recursive calls. + */ +int +sudo_putenv_nodebug(char *str, bool dupcheck, bool overwrite) +{ + char **ep; + const char *equal; + bool found = false; + + /* Some putenv(3) implementations check for NULL. */ + if (str == NULL) { + errno = EINVAL; + return -1; + } + + /* The string must contain a '=' char but not start with one. */ + equal = strchr(str, '='); + if (equal == NULL || equal == str) { + errno = EINVAL; + return -1; + } + + /* Make sure there is room for the new entry plus a NULL. */ + if (env.env_size > 2 && env.env_len > env.env_size - 2) { + char **nenvp; + size_t nsize; + + if (env.env_size > SIZE_MAX - 128) { + sudo_warnx_nodebug(U_("internal error, %s overflow"), + "sudo_putenv_nodebug"); + errno = EOVERFLOW; + return -1; + } + nsize = env.env_size + 128; + if (nsize > SIZE_MAX / sizeof(char *)) { + sudo_warnx_nodebug(U_("internal error, %s overflow"), + "sudo_putenv_nodebug"); + errno = EOVERFLOW; + return -1; + } + sudoers_gc_remove(GC_PTR, env.envp); + nenvp = reallocarray(env.envp, nsize, sizeof(char *)); + if (nenvp == NULL) { + sudoers_gc_add(GC_PTR, env.envp); + return -1; + } + sudoers_gc_add(GC_PTR, nenvp); + env.envp = nenvp; + env.env_size = nsize; +#ifdef ENV_DEBUG + memset(env.envp + env.env_len, 0, + (env.env_size - env.env_len) * sizeof(char *)); +#endif + } + +#ifdef ENV_DEBUG + if (env.envp[env.env_len] != NULL) { + errno = EINVAL; + return -1; + } +#endif + + if (dupcheck) { + size_t len = (size_t)(equal - str) + 1; + for (ep = env.envp; *ep != NULL; ep++) { + if (strncmp(str, *ep, len) == 0) { + if (overwrite) + *ep = str; + found = true; + break; + } + } + /* Prune out extra instances of the variable we just overwrote. */ + if (found && overwrite) { + while (*++ep != NULL) { + if (strncmp(str, *ep, len) == 0) { + char **cur = ep; + while ((*cur = *(cur + 1)) != NULL) + cur++; + ep--; + } + } + env.env_len = ep - env.envp; + } + } + + if (!found) { + ep = env.envp + env.env_len; + env.env_len++; + *ep++ = str; + *ep = NULL; + } + return 0; +} + +/* + * Similar to putenv(3) but operates on sudo's private copy of the + * environment (not environ) and it always overwrites. The dupcheck param + * determines whether we need to verify that the variable is not already set. + * Will only overwrite an existing variable if overwrite is set. + */ +static int +sudo_putenv(char *str, bool dupcheck, bool overwrite) +{ + int ret; + debug_decl(sudo_putenv, SUDOERS_DEBUG_ENV); + + sudo_debug_printf(SUDO_DEBUG_INFO, "sudo_putenv: %s", str); + + ret = sudo_putenv_nodebug(str, dupcheck, overwrite); + if (ret == -1) { +#ifdef ENV_DEBUG + if (env.envp[env.env_len] != NULL) { + sudo_warnx("%s", + U_("sudo_putenv: corrupted envp, length mismatch")); + } +#endif + } + debug_return_int(ret); +} + +/* + * Similar to setenv(3) but operates on a private copy of the environment. + * The dupcheck param determines whether we need to verify that the variable + * is not already set. + */ +static int +sudo_setenv2(const char *var, const char *val, bool dupcheck, bool overwrite) +{ + char *estring; + size_t esize; + int ret = -1; + debug_decl(sudo_setenv2, SUDOERS_DEBUG_ENV); + + esize = strlen(var) + 1 + strlen(val) + 1; + if ((estring = malloc(esize)) == NULL) { + sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO, + "unable to allocate memory"); + debug_return_int(-1); + } + + /* Build environment string and insert it. */ + if (strlcpy(estring, var, esize) >= esize || + strlcat(estring, "=", esize) >= esize || + strlcat(estring, val, esize) >= esize) { + + sudo_warnx(U_("internal error, %s overflow"), __func__); + errno = EOVERFLOW; + } else { + ret = sudo_putenv(estring, dupcheck, overwrite); + } + if (ret == -1) + free(estring); + else + sudoers_gc_add(GC_PTR, estring); + debug_return_int(ret); +} + +/* + * Similar to setenv(3) but operates on a private copy of the environment. + */ +int +sudo_setenv(const char *var, const char *val, int overwrite) +{ + return sudo_setenv2(var, val, true, (bool)overwrite); +} + +/* + * Similar to unsetenv(3) but operates on a private copy of the environment. + * Does not include warnings or debugging to avoid recursive calls. + */ +int +sudo_unsetenv_nodebug(const char *var) +{ + char **ep = env.envp; + size_t len; + + if (ep == NULL || var == NULL || *var == '\0' || strchr(var, '=') != NULL) { + errno = EINVAL; + return -1; + } + + len = strlen(var); + while (*ep != NULL) { + if (strncmp(var, *ep, len) == 0 && (*ep)[len] == '=') { + /* Found it; shift remainder + NULL over by one. */ + char **cur = ep; + while ((*cur = *(cur + 1)) != NULL) + cur++; + env.env_len--; + /* Keep going, could be multiple instances of the var. */ + } else { + ep++; + } + } + return 0; +} + +/* + * Similar to unsetenv(3) but operates on a private copy of the environment. + */ +int +sudo_unsetenv(const char *name) +{ + int ret; + debug_decl(sudo_unsetenv, SUDOERS_DEBUG_ENV); + + sudo_debug_printf(SUDO_DEBUG_INFO, "sudo_unsetenv: %s", name); + + ret = sudo_unsetenv_nodebug(name); + + debug_return_int(ret); +} + +/* + * Similar to getenv(3) but operates on a private copy of the environment. + * Does not include warnings or debugging to avoid recursive calls. + */ +char * +sudo_getenv_nodebug(const char *name) +{ + char **ep, *val = NULL; + size_t namelen = 0; + + if (env.env_len != 0) { + /* For BSD compatibility, treat '=' in name like end of string. */ + while (name[namelen] != '\0' && name[namelen] != '=') + namelen++; + for (ep = env.envp; *ep != NULL; ep++) { + if (strncmp(*ep, name, namelen) == 0 && (*ep)[namelen] == '=') { + val = *ep + namelen + 1; + break; + } + } + } + return val; +} + +/* + * Similar to getenv(3) but operates on a private copy of the environment. + */ +char * +sudo_getenv(const char *name) +{ + char *val; + debug_decl(sudo_getenv, SUDOERS_DEBUG_ENV); + + sudo_debug_printf(SUDO_DEBUG_INFO, "sudo_getenv: %s", name); + + val = sudo_getenv_nodebug(name); + + debug_return_str(val); +} + +/* + * Check for var against patterns in the specified environment list. + * Returns true if the variable was found, else false. + */ +static bool +matches_env_list(const char *var, struct list_members *list, bool *full_match) +{ + struct list_member *cur; + bool is_logname = false; + debug_decl(matches_env_list, SUDOERS_DEBUG_ENV); + + switch (*var) { + case 'L': + if (strncmp(var, "LOGNAME=", 8) == 0) + is_logname = true; +#ifdef _AIX + else if (strncmp(var, "LOGIN=", 6) == 0) + is_logname = true; +#endif + break; + case 'U': + if (strncmp(var, "USER=", 5) == 0) + is_logname = true; + break; + } + + if (is_logname) { + /* + * We treat LOGIN, LOGNAME and USER specially. + * If one is preserved/deleted we want to preserve/delete them all. + */ + SLIST_FOREACH(cur, list, entries) { + if (matches_env_pattern(cur->value, "LOGNAME", full_match) || +#ifdef _AIX + matches_env_pattern(cur->value, "LOGIN", full_match) || +#endif + matches_env_pattern(cur->value, "USER", full_match)) + debug_return_bool(true); + } + } else { + SLIST_FOREACH(cur, list, entries) { + if (matches_env_pattern(cur->value, var, full_match)) + debug_return_bool(true); + } + } + debug_return_bool(false); +} + +/* + * Check the env_delete blocklist. + * Returns true if the variable was found, else false. + */ +static bool +matches_env_delete(const char *var) +{ + bool full_match; /* unused */ + debug_decl(matches_env_delete, SUDOERS_DEBUG_ENV); + + /* Skip anything listed in env_delete. */ + debug_return_bool(matches_env_list(var, &def_env_delete, &full_match)); +} + +/* + * Verify the TZ environment variable is safe. + * On many systems it is possible to set this to a pathname. + */ +static bool +tz_is_safe(const char *tzval) +{ + const char *cp; + char lastch; + debug_decl(tz_is_safe, SUDOERS_DEBUG_ENV); + + /* tzcode treats a value beginning with a ':' as a path. */ + if (tzval[0] == ':') + tzval++; + + /* Reject fully-qualified TZ that doesn't being with the zoneinfo dir. */ + if (tzval[0] == '/') { +#ifdef _PATH_ZONEINFO + if (strncmp(tzval, _PATH_ZONEINFO, sizeof(_PATH_ZONEINFO) - 1) != 0 || + tzval[sizeof(_PATH_ZONEINFO) - 1] != '/') + debug_return_bool(false); +#else + /* Assume the worst. */ + debug_return_bool(false); +#endif + } + + /* + * Make sure TZ only contains printable non-space characters + * and does not contain a '..' path element. + */ + lastch = '/'; + for (cp = tzval; *cp != '\0'; cp++) { + if (isspace((unsigned char)*cp) || !isprint((unsigned char)*cp)) + debug_return_bool(false); + if (lastch == '/' && cp[0] == '.' && cp[1] == '.' && + (cp[2] == '/' || cp[2] == '\0')) + debug_return_bool(false); + lastch = *cp; + } + + /* Reject extra long TZ values (even if not a path). */ + if ((size_t)(cp - tzval) >= PATH_MAX) + debug_return_bool(false); + + debug_return_bool(true); +} + +/* + * Apply the env_check list. + * Returns true if the variable is allowed, false if denied + * or -1 if no match. + */ +static int +matches_env_check(const char *var, bool *full_match) +{ + int keepit = -1; + debug_decl(matches_env_check, SUDOERS_DEBUG_ENV); + + /* Skip anything listed in env_check that includes '/' or '%'. */ + if (matches_env_list(var, &def_env_check, full_match)) { + if (strncmp(var, "TZ=", 3) == 0) { + /* Special case for TZ */ + keepit = tz_is_safe(var + 3); + } else { + const char *val = strchr(var, '='); + if (val != NULL) + keepit = !strpbrk(val + 1, "/%"); + } + } + debug_return_int(keepit); +} + +/* + * Check the env_keep list. + * Returns true if the variable is allowed else false. + */ +static bool +matches_env_keep(const char *var, bool *full_match) +{ + bool keepit = false; + debug_decl(matches_env_keep, SUDOERS_DEBUG_ENV); + + /* Preserve SHELL variable for "sudo -s". */ + if (ISSET(sudo_mode, MODE_SHELL) && strncmp(var, "SHELL=", 6) == 0) { + keepit = true; + } else if (matches_env_list(var, &def_env_keep, full_match)) { + keepit = true; + } + debug_return_bool(keepit); +} + +/* + * Look up var in the env_delete and env_check. + * Returns true if we should delete the variable, else false. + */ +static bool +env_should_delete(const char *var) +{ + int delete_it; + bool full_match = false; + debug_decl(env_should_delete, SUDOERS_DEBUG_ENV); + + delete_it = matches_env_delete(var); + if (!delete_it) + delete_it = matches_env_check(var, &full_match) == false; + + sudo_debug_printf(SUDO_DEBUG_INFO, "delete %s: %s", + var, delete_it ? "YES" : "NO"); + debug_return_bool(delete_it); +} + +/* + * Lookup var in the env_check and env_keep lists. + * Returns true if the variable is allowed else false. + */ +static bool +env_should_keep(const char *var) +{ + int keepit; + bool full_match = false; + const char *cp; + debug_decl(env_should_keep, SUDOERS_DEBUG_ENV); + + keepit = matches_env_check(var, &full_match); + if (keepit == -1) + keepit = matches_env_keep(var, &full_match); + + /* Skip bash functions unless we matched on the value as well as name. */ + if (keepit && !full_match) { + if ((cp = strchr(var, '=')) != NULL) { + if (strncmp(cp, "=() ", 4) == 0) + keepit = false; + } + } + sudo_debug_printf(SUDO_DEBUG_INFO, "keep %s: %s", + var, keepit == true ? "YES" : "NO"); + debug_return_bool(keepit == true); +} + +#ifdef HAVE_PAM +/* + * Merge another environment with our private copy. + * Only overwrite an existing variable if it is not + * being preserved from the user's environment. + * Returns true on success or false on failure. + */ +bool +env_merge(char * const envp[]) +{ + char * const *ep; + bool ret = true; + debug_decl(env_merge, SUDOERS_DEBUG_ENV); + + for (ep = envp; *ep != NULL; ep++) { + /* XXX - avoid checking value here, should only check name */ + bool overwrite = def_env_reset ? !env_should_keep(*ep) : env_should_delete(*ep); + if (sudo_putenv(*ep, true, overwrite) == -1) { + /* XXX cannot undo on failure */ + ret = false; + break; + } + } + debug_return_bool(ret); +} +#endif /* HAVE_PAM */ + +static void +env_update_didvar(const char *ep, unsigned int *didvar) +{ + switch (*ep) { + case 'H': + if (strncmp(ep, "HOME=", 5) == 0) + SET(*didvar, DID_HOME); + break; + case 'L': +#ifdef _AIX + if (strncmp(ep, "LOGIN=", 8) == 0) + SET(*didvar, DID_LOGIN); +#endif + if (strncmp(ep, "LOGNAME=", 8) == 0) + SET(*didvar, DID_LOGNAME); + break; + case 'M': + if (strncmp(ep, "MAIL=", 5) == 0) + SET(*didvar, DID_MAIL); + break; + case 'P': + if (strncmp(ep, "PATH=", 5) == 0) + SET(*didvar, DID_PATH); + break; + case 'S': + if (strncmp(ep, "SHELL=", 6) == 0) + SET(*didvar, DID_SHELL); + break; + case 'T': + if (strncmp(ep, "TERM=", 5) == 0) + SET(*didvar, DID_TERM); + break; + case 'U': + if (strncmp(ep, "USER=", 5) == 0) + SET(*didvar, DID_USER); + break; + } +} + +#define CHECK_PUTENV(a, b, c) do { \ + if (sudo_putenv((char *)(a), (b), (c)) == -1) { \ + goto bad; \ + } \ +} while (0) + +#define CHECK_SETENV2(a, b, c, d) do { \ + if (sudo_setenv2((char *)(a), (b), (c), (d)) == -1) { \ + goto bad; \ + } \ +} while (0) + +/* + * Build a new environment and either clear potentially dangerous + * variables from the old one or start with a clean slate. + * Also adds sudo-specific variables (SUDO_*). + * Returns true on success or false on failure. + */ +bool +rebuild_env(void) +{ + char **ep, *cp, *ps1; + char idbuf[MAX_UID_T_LEN + 1]; + unsigned int didvar; + bool reset_home = false; + debug_decl(rebuild_env, SUDOERS_DEBUG_ENV); + + /* + * Either clean out the environment or reset to a safe default. + */ + ps1 = NULL; + didvar = 0; + env.env_len = 0; + env.env_size = 128; + sudoers_gc_remove(GC_PTR, env.old_envp); + free(env.old_envp); + env.old_envp = env.envp; + env.envp = reallocarray(NULL, env.env_size, sizeof(char *)); + if (env.envp == NULL) { + sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO, + "unable to allocate memory"); + env.env_size = 0; + goto bad; + } + sudoers_gc_add(GC_PTR, env.envp); +#ifdef ENV_DEBUG + memset(env.envp, 0, env.env_size * sizeof(char *)); +#else + env.envp[0] = NULL; +#endif + + /* Reset HOME based on target user if configured to. */ + if (ISSET(sudo_mode, MODE_RUN)) { + if (def_always_set_home || + ISSET(sudo_mode, MODE_RESET_HOME | MODE_LOGIN_SHELL) || + (ISSET(sudo_mode, MODE_SHELL) && def_set_home)) + reset_home = true; + } + + if (def_env_reset || ISSET(sudo_mode, MODE_LOGIN_SHELL)) { + /* + * If starting with a fresh environment, initialize it based on + * /etc/environment or login.conf. For "sudo -i" we want those + * variables to override the invoking user's environment, so we + * defer reading them until later. + */ + if (!ISSET(sudo_mode, MODE_LOGIN_SHELL)) { +#ifdef HAVE_LOGIN_CAP_H + /* Insert login class environment variables. */ + if (login_class) { + login_cap_t *lc = login_getclass(login_class); + if (lc != NULL) { + setusercontext(lc, runas_pw, runas_pw->pw_uid, + LOGIN_SETPATH|LOGIN_SETENV); + login_close(lc); + } + } +#endif /* HAVE_LOGIN_CAP_H */ +#if defined(_AIX) || (defined(__linux__) && !defined(HAVE_PAM)) + /* Insert system-wide environment variables. */ + if (!read_env_file(_PATH_ENVIRONMENT, true, false)) + sudo_warn("%s", _PATH_ENVIRONMENT); +#endif + for (ep = env.envp; *ep; ep++) + env_update_didvar(*ep, &didvar); + } + + /* Pull in vars we want to keep from the old environment. */ + if (env.old_envp != NULL) { + for (ep = env.old_envp; *ep; ep++) { + bool keepit; + + /* + * Look up the variable in the env_check and env_keep lists. + */ + keepit = env_should_keep(*ep); + + /* + * Do SUDO_PS1 -> PS1 conversion. + * This must happen *after* env_should_keep() is called. + */ + if (strncmp(*ep, "SUDO_PS1=", 9) == 0) + ps1 = *ep + 5; + + if (keepit) { + /* Preserve variable. */ + CHECK_PUTENV(*ep, true, false); + env_update_didvar(*ep, &didvar); + } + } + } + didvar |= didvar << 16; /* convert DID_* to KEPT_* */ + + /* + * Add in defaults. In -i mode these come from the runas user, + * otherwise they may be from the user's environment (depends + * on sudoers options). + */ + if (ISSET(sudo_mode, MODE_LOGIN_SHELL)) { + CHECK_SETENV2("SHELL", runas_pw->pw_shell, + ISSET(didvar, DID_SHELL), true); +#ifdef _AIX + CHECK_SETENV2("LOGIN", runas_pw->pw_name, + ISSET(didvar, DID_LOGIN), true); +#endif + CHECK_SETENV2("LOGNAME", runas_pw->pw_name, + ISSET(didvar, DID_LOGNAME), true); + CHECK_SETENV2("USER", runas_pw->pw_name, + ISSET(didvar, DID_USER), true); + } else { + /* We will set LOGNAME later in the def_set_logname case. */ + if (!def_set_logname) { +#ifdef _AIX + if (!ISSET(didvar, DID_LOGIN)) + CHECK_SETENV2("LOGIN", user_name, false, true); +#endif + if (!ISSET(didvar, DID_LOGNAME)) + CHECK_SETENV2("LOGNAME", user_name, false, true); + if (!ISSET(didvar, DID_USER)) + CHECK_SETENV2("USER", user_name, false, true); + } + } + + /* If we didn't keep HOME, reset it based on target user. */ + if (!ISSET(didvar, KEPT_HOME)) + reset_home = true; + + /* + * Set MAIL to target user in -i mode or if MAIL is not preserved + * from user's environment. + */ + if (ISSET(sudo_mode, MODE_LOGIN_SHELL) || !ISSET(didvar, KEPT_MAIL)) { + if (_PATH_MAILDIR[sizeof(_PATH_MAILDIR) - 2] == '/') { + if (asprintf(&cp, "MAIL=%s%s", _PATH_MAILDIR, runas_pw->pw_name) == -1) + goto bad; + } else { + if (asprintf(&cp, "MAIL=%s/%s", _PATH_MAILDIR, runas_pw->pw_name) == -1) + goto bad; + } + if (sudo_putenv(cp, ISSET(didvar, DID_MAIL), true) == -1) { + free(cp); + goto bad; + } + sudoers_gc_add(GC_PTR, cp); + } + } else { + /* + * Copy environ entries as long as they don't match env_delete or + * env_check. + */ + if (env.old_envp != NULL) { + for (ep = env.old_envp; *ep; ep++) { + /* Add variable unless it matches a blocklist. */ + if (!env_should_delete(*ep)) { + if (strncmp(*ep, "SUDO_PS1=", 9) == 0) + ps1 = *ep + 5; + else if (strncmp(*ep, "SHELL=", 6) == 0) + SET(didvar, DID_SHELL); + else if (strncmp(*ep, "PATH=", 5) == 0) + SET(didvar, DID_PATH); + else if (strncmp(*ep, "TERM=", 5) == 0) + SET(didvar, DID_TERM); + CHECK_PUTENV(*ep, true, false); + } + } + } + } + /* Replace the PATH envariable with a secure one? */ + if (def_secure_path && !user_is_exempt()) { + CHECK_SETENV2("PATH", def_secure_path, true, true); + SET(didvar, DID_PATH); + } + + /* + * Set LOGIN, LOGNAME, and USER to target if "set_logname" is not + * disabled. We skip this if we are running a login shell (because + * they have already been set). + */ + if (def_set_logname && !ISSET(sudo_mode, MODE_LOGIN_SHELL)) { + if ((didvar & KEPT_USER_VARIABLES) == 0) { + /* Nothing preserved, set them all. */ +#ifdef _AIX + CHECK_SETENV2("LOGIN", runas_pw->pw_name, true, true); +#endif + CHECK_SETENV2("LOGNAME", runas_pw->pw_name, true, true); + CHECK_SETENV2("USER", runas_pw->pw_name, true, true); + } else if ((didvar & KEPT_USER_VARIABLES) != KEPT_USER_VARIABLES) { + /* + * Preserved some of LOGIN, LOGNAME, USER but not all. + * Make the unset ones match so we don't end up with some + * set to the invoking user and others set to the runas user. + */ + if (ISSET(didvar, KEPT_LOGNAME)) + cp = sudo_getenv("LOGNAME"); +#ifdef _AIX + else if (ISSET(didvar, KEPT_LOGIN)) + cp = sudo_getenv("LOGIN"); +#endif + else if (ISSET(didvar, KEPT_USER)) + cp = sudo_getenv("USER"); + else + cp = NULL; + if (cp != NULL) { +#ifdef _AIX + if (!ISSET(didvar, KEPT_LOGIN)) + CHECK_SETENV2("LOGIN", cp, true, true); +#endif + if (!ISSET(didvar, KEPT_LOGNAME)) + CHECK_SETENV2("LOGNAME", cp, true, true); + if (!ISSET(didvar, KEPT_USER)) + CHECK_SETENV2("USER", cp, true, true); + } + } + } + + /* Set $HOME to target user if not preserving user's value. */ + if (reset_home) + CHECK_SETENV2("HOME", runas_pw->pw_dir, true, true); + + /* Provide default values for $SHELL, $TERM and $PATH if not set. */ + if (!ISSET(didvar, DID_SHELL)) + CHECK_SETENV2("SHELL", runas_pw->pw_shell, false, false); + if (!ISSET(didvar, DID_TERM)) + CHECK_PUTENV("TERM=unknown", false, false); + if (!ISSET(didvar, DID_PATH)) + CHECK_SETENV2("PATH", _PATH_STDPATH, false, true); + + /* Set PS1 if SUDO_PS1 is set. */ + if (ps1 != NULL) + CHECK_PUTENV(ps1, true, true); + + /* Add the SUDO_COMMAND envariable (cmnd + args). */ + if (user_args) { + /* + * We limit user_args to 4096 bytes to avoid an execve() failure + * for very long argument vectors. The command's environment also + * counts against the ARG_MAX limit. + */ + if (asprintf(&cp, "SUDO_COMMAND=%s %.*s", user_cmnd, 4096, user_args) == -1) + goto bad; + if (sudo_putenv(cp, true, true) == -1) { + free(cp); + goto bad; + } + sudoers_gc_add(GC_PTR, cp); + } else { + CHECK_SETENV2("SUDO_COMMAND", user_cmnd, true, true); + } + + /* Add the SUDO_USER, SUDO_UID, SUDO_GID environment variables. */ + CHECK_SETENV2("SUDO_USER", user_name, true, true); + (void)snprintf(idbuf, sizeof(idbuf), "%u", (unsigned int) user_uid); + CHECK_SETENV2("SUDO_UID", idbuf, true, true); + (void)snprintf(idbuf, sizeof(idbuf), "%u", (unsigned int) user_gid); + CHECK_SETENV2("SUDO_GID", idbuf, true, true); + + debug_return_bool(true); + +bad: + sudo_warn("%s", U_("unable to rebuild the environment")); + debug_return_bool(false); +} + +/* + * Insert all environment variables in envp into the private copy + * of the environment. + * Returns true on success or false on failure. + */ +bool +insert_env_vars(char * const envp[]) +{ + char * const *ep; + bool ret = true; + debug_decl(insert_env_vars, SUDOERS_DEBUG_ENV); + + /* Add user-specified environment variables. */ + if (envp != NULL) { + for (ep = envp; *ep != NULL; ep++) { + /* XXX - no undo on failure */ + if (sudo_putenv(*ep, true, true) == -1) { + ret = false; + break; + } + } + } + debug_return_bool(ret); +} + +/* + * Validate the list of environment variables passed in on the command + * line against env_delete, env_check, and env_keep. + * Calls log_warning() if any specified variables are not allowed. + * Returns true if allowed, else false. + */ +bool +validate_env_vars(char * const env_vars[]) +{ + char * const *ep; + char errbuf[4096]; + char *errpos = errbuf; + bool okvar, ret = true; + debug_decl(validate_env_vars, SUDOERS_DEBUG_ENV); + + if (env_vars == NULL) + debug_return_bool(true); /* nothing to do */ + + /* Add user-specified environment variables. */ + for (ep = env_vars; *ep != NULL; ep++) { + char *eq = strchr(*ep, '='); + if (eq == NULL || eq == *ep) { + /* Must be in the form var=val. */ + okvar = false; + } else if (def_secure_path && !user_is_exempt() && + strncmp(*ep, "PATH=", 5) == 0) { + okvar = false; + } else if (def_env_reset) { + okvar = env_should_keep(*ep); + } else { + okvar = !env_should_delete(*ep); + } + if (okvar == false) { + /* Not allowed, append to error buffer if space remains. */ + if (errpos < &errbuf[sizeof(errbuf)]) { + size_t varlen = strcspn(*ep, "="); + int len = snprintf(errpos, sizeof(errbuf) - (errpos - errbuf), + "%s%.*s", errpos != errbuf ? ", " : "", (int)varlen, *ep); + if (len >= ssizeof(errbuf) - (errpos - errbuf)) { + memcpy(&errbuf[sizeof(errbuf) - 4], "...", 4); + errpos = &errbuf[sizeof(errbuf)]; + } else { + errpos += len; + } + } + } + } + if (errpos != errbuf) { + /* XXX - audit? */ + log_warningx(0, + N_("sorry, you are not allowed to set the following environment variables: %s"), errbuf); + ret = false; + } + debug_return_bool(ret); +} + +static void * +env_file_open_local(const char *path) +{ + struct env_file_local *efl; + debug_decl(env_file_open_local, SUDOERS_DEBUG_ENV); + + efl = calloc(1, sizeof(*efl)); + if (efl != NULL) { + if ((efl->fp = fopen(path, "r")) == NULL) { + if (errno != ENOENT) { + free(efl); + efl = NULL; + } + } + } + debug_return_ptr(efl); +} + +static void +env_file_close_local(void *cookie) +{ + struct env_file_local *efl = cookie; + debug_decl(env_file_close_local, SUDOERS_DEBUG_ENV); + + if (efl != NULL) { + if (efl->fp != NULL) + fclose(efl->fp); + free(efl->line); + free(efl); + } + debug_return; +} + +/* + * Parse /etc/environment lines ala AIX and Linux. + * Lines may be in either of three formats: + * NAME=VALUE + * NAME="VALUE" + * NAME='VALUE' + * with an optional "export" prefix so the shell can source the file. + * Invalid lines, blank lines, or lines consisting solely of a comment + * character are skipped. + */ +static char * +env_file_next_local(void *cookie, int *errnum) +{ + struct env_file_local *efl = cookie; + char *var, *val, *ret = NULL; + size_t var_len, val_len; + debug_decl(env_file_next_local, SUDOERS_DEBUG_ENV); + + *errnum = 0; + if (efl->fp == NULL) + debug_return_ptr(NULL); + + for (;;) { + if (sudo_parseln(&efl->line, &efl->linesize, NULL, efl->fp, PARSELN_CONT_IGN) == -1) { + if (!feof(efl->fp)) + *errnum = errno; + break; + } + + /* Skip blank or comment lines */ + if (*(var = efl->line) == '\0') + continue; + + /* Skip optional "export " */ + if (strncmp(var, "export", 6) == 0 && isspace((unsigned char) var[6])) { + var += 7; + while (isspace((unsigned char) *var)) { + var++; + } + } + + /* Must be of the form name=["']value['"] */ + for (val = var; *val != '\0' && *val != '='; val++) + continue; + if (var == val || *val != '=') + continue; + var_len = (size_t)(val - var); + val_len = strlen(++val); + + /* Strip leading and trailing single/double quotes */ + if ((val[0] == '\'' || val[0] == '\"') && val_len > 1 && val[0] == val[val_len - 1]) { + val[val_len - 1] = '\0'; + val++; + val_len -= 2; + } + + if ((ret = malloc(var_len + 1 + val_len + 1)) == NULL) { + *errnum = errno; + sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO, + "unable to allocate memory"); + } else { + memcpy(ret, var, var_len + 1); /* includes '=' */ + memcpy(ret + var_len + 1, val, val_len + 1); /* includes NUL */ + sudoers_gc_add(GC_PTR, ret); + } + break; + } + debug_return_str(ret); +} + +static struct sudoers_env_file env_file_sudoers = { + env_file_open_local, + env_file_close_local, + env_file_next_local +}; + +static struct sudoers_env_file env_file_system = { + env_file_open_local, + env_file_close_local, + env_file_next_local +}; + +void +register_env_file(void * (*ef_open)(const char *), void (*ef_close)(void *), + char * (*ef_next)(void *, int *), bool sys) +{ + struct sudoers_env_file *ef = sys ? &env_file_system : &env_file_sudoers; + + ef->open = ef_open; + ef->close = ef_close; + ef->next = ef_next; +} + +bool +read_env_file(const char *path, bool overwrite, bool restricted) +{ + struct sudoers_env_file *ef; + bool ret = true; + char *envstr; + void *cookie; + int errnum; + debug_decl(read_env_file, SUDOERS_DEBUG_ENV); + + /* + * The environment file may be handled differently depending on + * whether it is specified in sudoers or the system. + */ + if (path == def_env_file || path == def_restricted_env_file) + ef = &env_file_sudoers; + else + ef = &env_file_system; + + cookie = ef->open(path); + if (cookie == NULL) + debug_return_bool(false); + + for (;;) { + /* Keep reading until EOF or error. */ + if ((envstr = ef->next(cookie, &errnum)) == NULL) { + if (errnum != 0) + ret = false; + break; + } + + /* + * If the env file is restricted, apply env_check and env_keep + * when env_reset is set or env_delete when it is not. + */ + if (restricted) { + if (def_env_reset ? !env_should_keep(envstr) : env_should_delete(envstr)) { + free(envstr); + continue; + } + } + if (sudo_putenv(envstr, true, overwrite) == -1) { + /* XXX - no undo on failure */ + ret = false; + break; + } + } + ef->close(cookie); + + debug_return_bool(ret); +} + +bool +init_envtables(void) +{ + struct list_member *cur; + const char **p; + debug_decl(init_envtables, SUDOERS_DEBUG_ENV); + + /* Fill in the "env_delete" list. */ + for (p = initial_badenv_table; *p; p++) { + cur = calloc(1, sizeof(struct list_member)); + if (cur == NULL || (cur->value = strdup(*p)) == NULL) { + sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO, + "unable to allocate memory"); + free(cur); + debug_return_bool(false); + } + SLIST_INSERT_HEAD(&def_env_delete, cur, entries); + } + + /* Fill in the "env_check" list. */ + for (p = initial_checkenv_table; *p; p++) { + cur = calloc(1, sizeof(struct list_member)); + if (cur == NULL || (cur->value = strdup(*p)) == NULL) { + sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO, + "unable to allocate memory"); + free(cur); + debug_return_bool(false); + } + SLIST_INSERT_HEAD(&def_env_check, cur, entries); + } + + /* Fill in the "env_keep" list. */ + for (p = initial_keepenv_table; *p; p++) { + cur = calloc(1, sizeof(struct list_member)); + if (cur == NULL || (cur->value = strdup(*p)) == NULL) { + sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO, + "unable to allocate memory"); + free(cur); + debug_return_bool(false); + } + SLIST_INSERT_HEAD(&def_env_keep, cur, entries); + } + debug_return_bool(true); +} |