/************************************************************************ * * newrole * * SYNOPSIS: * * This program allows a user to change their SELinux RBAC role and/or * SELinux TE type (domain) in a manner similar to the way the traditional * UNIX su program allows a user to change their identity. * * USAGE: * * newrole [ -r role ] [ -t type ] [ -l level ] [ -V ] [ -- args ] * * BUILD OPTIONS: * * option USE_PAM: * * Set the USE_PAM constant if you want to authenticate users via PAM. * If USE_PAM is not set, users will be authenticated via direct * access to the shadow password file. * * If you decide to use PAM must be told how to handle newrole. A * good rule-of-thumb might be to tell PAM to handle newrole in the * same way it handles su, except that you should remove the pam_rootok.so * entry so that even root must re-authenticate to change roles. * * If you choose not to use PAM, make sure you have a shadow passwd file * in /etc/shadow. You can use a symlink if your shadow passwd file * lives in another directory. Example: * su * cd /etc * ln -s /etc/auth/shadow shadow * * If you decide not to use PAM, you will also have to make newrole * setuid root, so that it can read the shadow passwd file. * * * Authors: * Anthony Colatrella * Tim Fraser * Steve Grubb * Darrel Goeddel * Michael Thompson * Dan Walsh * *************************************************************************/ #define _GNU_SOURCE #if defined(AUDIT_LOG_PRIV) && !defined(USE_AUDIT) #error AUDIT_LOG_PRIV needs the USE_AUDIT option #endif #if defined(NAMESPACE_PRIV) && !defined(USE_PAM) #error NAMESPACE_PRIV needs the USE_PAM option #endif #include #include /* for malloc(), realloc(), free() */ #include /* for getpwuid() */ #include #include /* to make getuid() and getpwuid() happy */ #include /* for wait() */ #include /* for getopt_long() form of getopt() */ #include #include #include #include /* for is_selinux_enabled() */ #include /* for SECCLASS_CHR_FILE */ #include /* for context-mangling functions */ #include #include /* for SELINUX_DEFAULTUSER */ #include #include /* for getuid(), exit(), getopt() */ #ifdef USE_AUDIT #include #endif #if defined(AUDIT_LOG_PRIV) || (NAMESPACE_PRIV) #include #include #endif #ifdef USE_NLS #include /* for setlocale() */ #include /* for gettext() */ #define _(msgid) gettext (msgid) #else #define _(msgid) (msgid) #endif #ifndef PACKAGE #define PACKAGE "policycoreutils" /* the name of this package lang translation */ #endif #define TRUE 1 #define FALSE 0 /* USAGE_STRING describes the command-line args of this program. */ #define USAGE_STRING "USAGE: newrole [ -r role ] [ -t type ] [ -l level ] [ -p ] [ -V ] [ -- args ]" #ifdef USE_PAM #define PAM_SERVICE_CONFIG "/etc/selinux/newrole_pam.conf"; #endif #define DEFAULT_PATH "/usr/bin:/bin" #define DEFAULT_CONTEXT_SIZE 255 /* first guess at context size */ extern char **environ; /** * Construct from the current range and specified desired level a resulting * range. If the specified level is a range, return that. If it is not, then * construct a range with level as the sensitivity and clearance of the current * context. * * newlevel - the level specified on the command line * range - the range in the current context * * Returns malloc'd memory */ static char *build_new_range(char *newlevel, const char *range) { char *newrangep = NULL; const char *tmpptr; size_t len; /* a missing or empty string */ if (!range || !strlen(range) || !newlevel || !strlen(newlevel)) return NULL; /* if the newlevel is actually a range - just use that */ if (strchr(newlevel, '-')) { newrangep = strdup(newlevel); return newrangep; } /* look for MLS range in current context */ tmpptr = strchr(range, '-'); if (tmpptr) { /* we are inserting into a ranged MLS context */ len = strlen(newlevel) + 1 + strlen(tmpptr + 1) + 1; newrangep = (char *)malloc(len); if (!newrangep) return NULL; snprintf(newrangep, len, "%s-%s", newlevel, tmpptr + 1); } else { /* we are inserting into a currently non-ranged MLS context */ if (!strcmp(newlevel, range)) { newrangep = strdup(range); } else { len = strlen(newlevel) + 1 + strlen(range) + 1; newrangep = (char *)malloc(len); if (!newrangep) return NULL; snprintf(newrangep, len, "%s-%s", newlevel, range); } } return newrangep; } #ifdef USE_PAM /************************************************************************ * * All PAM code goes in this section. * ************************************************************************/ #include /* for PAM functions */ #include /* for misc_conv PAM utility function */ char *service_name = "newrole"; /* authenticate_via_pam() * * in: pw - struct containing data from our user's line in * the passwd file. * out: nothing * return: value condition * ----- --------- * 1 PAM thinks that the user authenticated themselves properly * 0 otherwise * * This function uses PAM to authenticate the user running this * program. This is the only function in this program that makes PAM * calls. */ int authenticate_via_pam(const char *ttyn, pam_handle_t * pam_handle) { int result = 0; /* set to 0 (not authenticated) by default */ int pam_rc; /* pam return code */ const char *tty_name; if (ttyn) { if (strncmp(ttyn, "/dev/", 5) == 0) tty_name = ttyn + 5; else tty_name = ttyn; pam_rc = pam_set_item(pam_handle, PAM_TTY, tty_name); if (pam_rc != PAM_SUCCESS) { fprintf(stderr, _("failed to set PAM_TTY\n")); goto out; } } /* Ask PAM to authenticate the user running this program */ pam_rc = pam_authenticate(pam_handle, 0); if (pam_rc != PAM_SUCCESS) { goto out; } /* Ask PAM to verify acct_mgmt */ pam_rc = pam_acct_mgmt(pam_handle, 0); if (pam_rc == PAM_SUCCESS) { result = 1; /* user authenticated OK! */ } out: return result; } /* authenticate_via_pam() */ #include "hashtab.h" static int free_hashtab_entry(hashtab_key_t key, hashtab_datum_t d, void *args __attribute__ ((unused))) { free(key); free(d); return 0; } static unsigned int reqsymhash(hashtab_t h, hashtab_key_t key) { char *p, *keyp; size_t size; unsigned int val; val = 0; keyp = (char *)key; size = strlen(keyp); for (p = keyp; ((size_t) (p - keyp)) < size; p++) val = (val << 4 | (val >> (8 * sizeof(unsigned int) - 4))) ^ (*p); return val & (h->size - 1); } static int reqsymcmp(hashtab_t h __attribute__ ((unused)), hashtab_key_t key1, hashtab_key_t key2) { char *keyp1, *keyp2; keyp1 = (char *)key1; keyp2 = (char *)key2; return strcmp(keyp1, keyp2); } static hashtab_t app_service_names = NULL; #define PAM_SERVICE_SLOTS 64 static int process_pam_config(FILE * cfg) { const char *config_file_path = PAM_SERVICE_CONFIG; char *line_buf = NULL; unsigned long lineno = 0; size_t len = 0; char *app = NULL; char *service = NULL; int ret; while (getline(&line_buf, &len, cfg) > 0) { char *buffer = line_buf; lineno++; while (isspace(*buffer)) buffer++; if (buffer[0] == '#') continue; if (buffer[0] == '\n' || buffer[0] == '\0') continue; app = service = NULL; ret = sscanf(buffer, "%as %as\n", &app, &service); if (ret < 2 || !app || !service) goto err; ret = hashtab_insert(app_service_names, app, service); if (ret == HASHTAB_OVERFLOW) { fprintf(stderr, _ ("newrole: service name configuration hashtable overflow\n")); goto err; } } free(line_buf); return 0; err: free(app); free(service); fprintf(stderr, _("newrole: %s: error on line %lu.\n"), config_file_path, lineno); free(line_buf); return -1; } /* * Read config file ignoring comment lines. * Files specified one per line executable with a corresponding * pam service name. */ static int read_pam_config() { const char *config_file_path = PAM_SERVICE_CONFIG; FILE *cfg = NULL; cfg = fopen(config_file_path, "r"); if (!cfg) return 0; /* This configuration is optional. */ app_service_names = hashtab_create(reqsymhash, reqsymcmp, PAM_SERVICE_SLOTS); if (!app_service_names) goto err; if (process_pam_config(cfg)) goto err; fclose(cfg); return 0; err: fclose(cfg); return -1; } #else /* else !USE_PAM */ /************************************************************************ * * All shadow passwd code goes in this section. * ************************************************************************/ #include /* for shadow passwd functions */ #include /* for strlen(), memset() */ #define PASSWORD_PROMPT _("Password:") /* prompt for getpass() */ /* authenticate_via_shadow_passwd() * * in: uname - the calling user's user name * out: nothing * return: value condition * ----- --------- * 1 user authenticated themselves properly according to the * shadow passwd file. * 0 otherwise * * This function uses the shadow passwd file to thenticate the user running * this program. */ int authenticate_via_shadow_passwd(const char *uname) { struct spwd *p_shadow_line; char *unencrypted_password_s; char *encrypted_password_s; setspent(); p_shadow_line = getspnam(uname); endspent(); if (!(p_shadow_line)) { fprintf(stderr, _("Cannot find your entry in the shadow " "passwd file.\n")); return 0; } /* Ask user to input unencrypted password */ if (!(unencrypted_password_s = getpass(PASSWORD_PROMPT))) { fprintf(stderr, _("getpass cannot open /dev/tty\n")); return 0; } /* Use crypt() to encrypt user's input password. */ encrypted_password_s = crypt(unencrypted_password_s, p_shadow_line->sp_pwdp); memset(unencrypted_password_s, 0, strlen(unencrypted_password_s)); return (!strcmp(encrypted_password_s, p_shadow_line->sp_pwdp)); } #endif /* if/else USE_PAM */ /** * This function checks to see if the shell is known in /etc/shells. * If so, it returns 1. On error or illegal shell, it returns 0. */ static int verify_shell(const char *shell_name) { int found = 0; const char *buf; if (!(shell_name && shell_name[0])) return found; while ((buf = getusershell()) != NULL) { /* ignore comments */ if (*buf == '#') continue; /* check the shell skipping newline char */ if (!strcmp(shell_name, buf)) { found = 1; break; } } endusershell(); return found; } /** * Determine the Linux user identity to re-authenticate. * If supported and set, use the login uid, as this should be more stable. * Otherwise, use the real uid. * * This function assigns malloc'd memory into the pw_copy struct. * Returns zero on success, non-zero otherwise */ int extract_pw_data(struct passwd *pw_copy) { uid_t uid; struct passwd *pw; #ifdef USE_AUDIT uid = audit_getloginuid(); if (uid == (uid_t) - 1) uid = getuid(); #else uid = getuid(); #endif setpwent(); pw = getpwuid(uid); endpwent(); if (!(pw && pw->pw_name && pw->pw_name[0] && pw->pw_shell && pw->pw_shell[0] && pw->pw_dir && pw->pw_dir[0])) { fprintf(stderr, _("cannot find valid entry in the passwd file.\n")); return -1; } *pw_copy = *pw; pw = pw_copy; pw->pw_name = strdup(pw->pw_name); pw->pw_dir = strdup(pw->pw_dir); pw->pw_shell = strdup(pw->pw_shell); if (!(pw->pw_name && pw->pw_dir && pw->pw_shell)) { fprintf(stderr, _("Out of memory!\n")); goto out_free; } if (verify_shell(pw->pw_shell) == 0) { fprintf(stderr, _("Error! Shell is not valid.\n")); goto out_free; } return 0; out_free: free(pw->pw_name); free(pw->pw_dir); free(pw->pw_shell); return -1; } /** * Either restore the original environment, or set up a minimal one. * * The minimal environment contains: * TERM, DISPLAY and XAUTHORITY - if they are set, preserve values * HOME, SHELL, USER and LOGNAME - set to contents of /etc/passwd * PATH - set to default value DEFAULT_PATH * * Returns zero on success, non-zero otherwise */ static int restore_environment(int preserve_environment, char **old_environ, const struct passwd *pw) { char const *term_env; char const *display_env; char const *xauthority_env; char *term = NULL; /* temporary container */ char *display = NULL; /* temporary container */ char *xauthority = NULL; /* temporary container */ int rc; environ = old_environ; if (preserve_environment) return 0; term_env = getenv("TERM"); display_env = getenv("DISPLAY"); xauthority_env = getenv("XAUTHORITY"); /* Save the variable values we want */ if (term_env) term = strdup(term_env); if (display_env) display = strdup(display_env); if (xauthority_env) xauthority = strdup(xauthority_env); if ((term_env && !term) || (display_env && !display) || (xauthority_env && !xauthority)) { rc = -1; goto out; } /* Construct a new environment */ if ((rc = clearenv())) { fprintf(stderr, _("Unable to clear environment\n")); goto out; } /* Restore that which we saved */ if (term) rc |= setenv("TERM", term, 1); if (display) rc |= setenv("DISPLAY", display, 1); if (xauthority) rc |= setenv("XAUTHORITY", xauthority, 1); rc |= setenv("HOME", pw->pw_dir, 1); rc |= setenv("SHELL", pw->pw_shell, 1); rc |= setenv("USER", pw->pw_name, 1); rc |= setenv("LOGNAME", pw->pw_name, 1); rc |= setenv("PATH", DEFAULT_PATH, 1); out: free(term); free(display); free(xauthority); return rc; } /** * This function will drop the capabilities so that we are left * only with access to the audit system. If the user is root, we leave * the capabilities alone since they already should have access to the * audit netlink socket. * * Returns zero on success, non-zero otherwise */ #if defined(AUDIT_LOG_PRIV) && !defined(NAMESPACE_PRIV) static int drop_capabilities(int full) { capng_clear(CAPNG_SELECT_BOTH); if (capng_lock() < 0) return -1; uid_t uid = getuid(); if (!uid) return 0; /* Change uid */ if (setresuid(uid, uid, uid)) { fprintf(stderr, _("Error changing uid, aborting.\n")); return -1; } if (! full) capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED, CAP_AUDIT_WRITE); return capng_apply(CAPNG_SELECT_BOTH); } #elif defined(NAMESPACE_PRIV) /** * This function will drop the capabilities so that we are left * only with access to the audit system and the ability to raise * CAP_SYS_ADMIN, CAP_DAC_OVERRIDE, CAP_FOWNER and CAP_CHOWN, * before invoking pam_namespace. These capabilities are needed * for performing bind mounts/unmounts and to create potential new * instance directories with appropriate DAC attributes. If the * user is root, we leave the capabilities alone since they already * should have access to the audit netlink socket and should have * the ability to create/mount/unmount instance directories. * * Returns zero on success, non-zero otherwise */ static int drop_capabilities(int full) { capng_clear(CAPNG_SELECT_BOTH); if (capng_lock() < 0) return -1; uid_t uid = getuid(); /* Change uid */ if (setresuid(uid, uid, uid)) { fprintf(stderr, _("Error changing uid, aborting.\n")); return -1; } if (! full) capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED, CAP_SYS_ADMIN | CAP_FOWNER | CAP_CHOWN | CAP_DAC_OVERRIDE); return capng_apply(CAPNG_SELECT_BOTH); } #else static inline int drop_capabilities(__attribute__ ((__unused__)) int full) { return 0; } #endif #ifdef NAMESPACE_PRIV /** * This function will set the uid values to be that of caller's uid, and * will drop any privilages which maybe have been raised. */ static int transition_to_caller_uid() { uid_t uid = getuid(); if (prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0) < 0) { fprintf(stderr, _("Error resetting KEEPCAPS, aborting\n")); return -1; } if (setresuid(uid, uid, uid)) { fprintf(stderr, _("Error changing uid, aborting.\n")); return -1; } return 0; } #endif #ifdef AUDIT_LOG_PRIV /* Send audit message */ static int send_audit_message(int success, security_context_t old_context, security_context_t new_context, const char *ttyn) { char *msg = NULL; int rc; int audit_fd = audit_open(); if (audit_fd < 0) { fprintf(stderr, _("Error connecting to audit system.\n")); return -1; } if (asprintf(&msg, "newrole: old-context=%s new-context=%s", old_context ? old_context : "?", new_context ? new_context : "?") < 0) { fprintf(stderr, _("Error allocating memory.\n")); rc = -1; goto out; } rc = audit_log_user_message(audit_fd, AUDIT_USER_ROLE_CHANGE, msg, NULL, NULL, ttyn, success); if (rc <= 0) { fprintf(stderr, _("Error sending audit message.\n")); rc = -1; goto out; } rc = 0; out: free(msg); close(audit_fd); return rc; } #else static inline int send_audit_message(int success __attribute__ ((unused)), security_context_t old_context __attribute__ ((unused)), security_context_t new_context __attribute__ ((unused)), const char *ttyn __attribute__ ((unused))) { return 0; } #endif /** * This function attempts to relabel the tty. If this function fails, then * the fd is closed, the contexts are free'd and -1 is returned. On success, * a valid fd is returned and tty_context and new_tty_context are set. * * This function will not fail if it can not relabel the tty when selinux is * in permissive mode. */ static int relabel_tty(const char *ttyn, security_context_t new_context, security_context_t * tty_context, security_context_t * new_tty_context) { int fd; int enforcing = security_getenforce(); security_context_t tty_con = NULL; security_context_t new_tty_con = NULL; if (!ttyn) return 0; if (enforcing < 0) { fprintf(stderr, _("Could not determine enforcing mode.\n")); return -1; } /* Re-open TTY descriptor */ fd = open(ttyn, O_RDWR | O_NONBLOCK); if (fd < 0) { fprintf(stderr, _("Error! Could not open %s.\n"), ttyn); return fd; } fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK); if (fgetfilecon(fd, &tty_con) < 0) { fprintf(stderr, _("%s! Could not get current context " "for %s, not relabeling tty.\n"), enforcing ? "Error" : "Warning", ttyn); if (enforcing) goto close_fd; } if (tty_con && (security_compute_relabel(new_context, tty_con, SECCLASS_CHR_FILE, &new_tty_con) < 0)) { fprintf(stderr, _("%s! Could not get new context for %s, " "not relabeling tty.\n"), enforcing ? "Error" : "Warning", ttyn); if (enforcing) goto close_fd; } if (new_tty_con) if (fsetfilecon(fd, new_tty_con) < 0) { fprintf(stderr, _("%s! Could not set new context for %s\n"), enforcing ? "Error" : "Warning", ttyn); freecon(new_tty_con); new_tty_con = NULL; if (enforcing) goto close_fd; } *tty_context = tty_con; *new_tty_context = new_tty_con; return fd; close_fd: freecon(tty_con); close(fd); return -1; } /** * This function attempts to revert the relabeling done to the tty. * fd - referencing the opened ttyn * ttyn - name of tty to restore * tty_context - original context of the tty * new_tty_context - context tty was relabeled to * * Returns zero on success, non-zero otherwise */ static int restore_tty_label(int fd, const char *ttyn, security_context_t tty_context, security_context_t new_tty_context) { int rc = 0; security_context_t chk_tty_context = NULL; if (!ttyn) goto skip_relabel; if (!new_tty_context) goto skip_relabel; /* Verify that the tty still has the context set by newrole. */ if ((rc = fgetfilecon(fd, &chk_tty_context)) < 0) { fprintf(stderr, "Could not fgetfilecon %s.\n", ttyn); goto skip_relabel; } if ((rc = strcmp(chk_tty_context, new_tty_context))) { fprintf(stderr, _("%s changed labels.\n"), ttyn); goto skip_relabel; } if ((rc = fsetfilecon(fd, tty_context)) < 0) fprintf(stderr, _("Warning! Could not restore context for %s\n"), ttyn); skip_relabel: freecon(chk_tty_context); return rc; } /** * Parses and validates the provided command line options and * constructs a new context based on our old context and the * arguments specified on the command line. On success * new_context will be set to valid values, otherwise its value * is left unchanged. * * Returns zero on success, non-zero otherwise. */ static int parse_command_line_arguments(int argc, char **argv, char *ttyn, security_context_t old_context, security_context_t * new_context, int *preserve_environment) { int flag_index; /* flag index in argv[] */ int clflag; /* holds codes for command line flags */ char *role_s = NULL; /* role spec'd by user in argv[] */ char *type_s = NULL; /* type spec'd by user in argv[] */ char *type_ptr = NULL; /* stores malloc'd data from get_default_type */ char *level_s = NULL; /* level spec'd by user in argv[] */ char *range_ptr = NULL; security_context_t new_con = NULL; security_context_t tty_con = NULL; context_t context = NULL; /* manipulatable form of new_context */ const struct option long_options[] = { {"role", 1, 0, 'r'}, {"type", 1, 0, 't'}, {"level", 1, 0, 'l'}, {"preserve-environment", 0, 0, 'p'}, {"version", 0, 0, 'V'}, {NULL, 0, 0, 0} }; *preserve_environment = 0; while (1) { clflag = getopt_long(argc, argv, "r:t:l:pV", long_options, &flag_index); if (clflag == -1) break; switch (clflag) { case 'V': printf("newrole: %s version %s\n", PACKAGE, VERSION); exit(0); break; case 'p': *preserve_environment = 1; break; case 'r': if (role_s) { fprintf(stderr, _("Error: multiple roles specified\n")); return -1; } role_s = optarg; break; case 't': if (type_s) { fprintf(stderr, _("Error: multiple types specified\n")); return -1; } type_s = optarg; break; case 'l': if (!is_selinux_mls_enabled()) { fprintf(stderr, _("Sorry, -l may be used with " "SELinux MLS support.\n")); return -1; } if (level_s) { fprintf(stderr, _("Error: multiple levels " "specified\n")); return -1; } if (ttyn) { if (fgetfilecon(STDIN_FILENO, &tty_con) >= 0) { if (selinux_check_securetty_context (tty_con) < 0) { fprintf(stderr, _ ("Error: you are not allowed to change levels on a non secure terminal \n")); freecon(tty_con); return -1; } freecon(tty_con); } } level_s = optarg; break; default: fprintf(stderr, "%s\n", USAGE_STRING); return -1; } } /* Verify that the combination of command-line arguments are viable */ if (!(role_s || type_s || level_s)) { fprintf(stderr, "%s\n", USAGE_STRING); return -1; } /* Fill in a default type if one hasn't been specified. */ if (role_s && !type_s) { /* get_default_type() returns malloc'd memory */ if (get_default_type(role_s, &type_ptr)) { fprintf(stderr, _("Couldn't get default type.\n")); send_audit_message(0, old_context, new_con, ttyn); return -1; } type_s = type_ptr; } /* Create a temporary new context structure we extract and modify */ context = context_new(old_context); if (!context) { fprintf(stderr, _("failed to get new context.\n")); goto err_free; } /* Modify the temporary new context */ if (role_s) if (context_role_set(context, role_s)) { fprintf(stderr, _("failed to set new role %s\n"), role_s); goto err_free; } if (type_s) if (context_type_set(context, type_s)) { fprintf(stderr, _("failed to set new type %s\n"), type_s); goto err_free; } if (level_s) { range_ptr = build_new_range(level_s, context_range_get(context)); if (!range_ptr) { fprintf(stderr, _("failed to build new range with level %s\n"), level_s); goto err_free; } if (context_range_set(context, range_ptr)) { fprintf(stderr, _("failed to set new range %s\n"), range_ptr); goto err_free; } } /* Construct the final new context */ if (!(new_con = context_str(context))) { fprintf(stderr, _("failed to convert new context to string\n")); goto err_free; } if (security_check_context(new_con) < 0) { fprintf(stderr, _("%s is not a valid context\n"), new_con); send_audit_message(0, old_context, new_con, ttyn); goto err_free; } *new_context = strdup(new_con); if (!*new_context) { fprintf(stderr, _("Unable to allocate memory for new_context")); goto err_free; } free(type_ptr); free(range_ptr); context_free(context); return 0; err_free: free(type_ptr); free(range_ptr); /* Don't free new_con, context_free(context) handles this */ context_free(context); return -1; } /** * Take care of any signal setup */ static int set_signal_handles() { sigset_t empty; /* Empty the signal mask in case someone is blocking a signal */ if (sigemptyset(&empty)) { fprintf(stderr, _("Unable to obtain empty signal set\n")); return -1; } (void)sigprocmask(SIG_SETMASK, &empty, NULL); /* Terminate on SIGHUP. */ if (signal(SIGHUP, SIG_DFL) == SIG_ERR) { fprintf(stderr, _("Unable to set SIGHUP handler\n")); return -1; } return 0; } /************************************************************************ * * All code used for both PAM and shadow passwd goes in this section. * ************************************************************************/ int main(int argc, char *argv[]) { security_context_t new_context = NULL; /* target security context */ security_context_t old_context = NULL; /* original securiy context */ security_context_t tty_context = NULL; /* current context of tty */ security_context_t new_tty_context = NULL; /* new context of tty */ struct passwd pw; /* struct derived from passwd file line */ char *ttyn = NULL; /* tty path */ char **old_environ; int preserve_environment; int fd; pid_t childPid = 0; char *shell_argv0 = NULL; #ifdef USE_PAM int rc; int pam_status; /* pam return code */ pam_handle_t *pam_handle; /* opaque handle used by all PAM functions */ /* This is a jump table of functions for PAM to use when it wants to * * communicate with the user. We'll be using misc_conv(), which is * * provided for us via pam_misc.h. */ struct pam_conv pam_conversation = { misc_conv, NULL }; #endif /* * Step 0: Setup * * Do some intial setup, including dropping capabilities, checking * if it makes sense to continue to run newrole, and setting up * a scrubbed environment. */ if (drop_capabilities(FALSE)) return -1; if (set_signal_handles()) return -1; #ifdef USE_NLS setlocale(LC_ALL, ""); bindtextdomain(PACKAGE, LOCALEDIR); textdomain(PACKAGE); #endif old_environ = environ; environ = NULL; if (!is_selinux_enabled()) { fprintf(stderr, _("Sorry, newrole may be used only on " "a SELinux kernel.\n")); return -1; } if (security_getenforce() < 0) { fprintf(stderr, _("Could not determine enforcing mode.\n")); return -1; } /* * Step 1: Parse command line and valid arguments * * old_context and ttyn are required for audit logging, * context validation and pam */ if (getprevcon(&old_context)) { fprintf(stderr, _("failed to get old_context.\n")); return -1; } ttyn = ttyname(STDIN_FILENO); if (!ttyn || *ttyn == '\0') { fprintf(stderr, _("Warning! Could not retrieve tty information.\n")); } if (parse_command_line_arguments(argc, argv, ttyn, old_context, &new_context, &preserve_environment)) return -1; /* * Step 2: Authenticate the user. * * Re-authenticate the user running this program. * This is just to help confirm user intent (vs. invocation by * malicious software), not to authorize the operation (which is covered * by policy). Trusted path mechanism would be preferred. */ if (extract_pw_data(&pw)) goto err_free; #ifdef USE_PAM if (read_pam_config()) { fprintf(stderr, _("error on reading PAM service configuration.\n")); goto err_free; } if (app_service_names != NULL && optind < argc) { if (strcmp(argv[optind], "-c") == 0 && optind < (argc - 1)) { /* * Check for a separate pam service name for the * command when invoked by newrole. */ char *cmd = NULL; rc = sscanf(argv[optind + 1], "%as", &cmd); if (rc != EOF && cmd) { char *app_service_name = (char *)hashtab_search(app_service_names, cmd); free(cmd); if (app_service_name != NULL) service_name = app_service_name; } } } pam_status = pam_start(service_name, pw.pw_name, &pam_conversation, &pam_handle); if (pam_status != PAM_SUCCESS) { fprintf(stderr, _("failed to initialize PAM\n")); goto err_free; } if (!authenticate_via_pam(ttyn, pam_handle)) #else if (!authenticate_via_shadow_passwd(pw.pw_name)) #endif { fprintf(stderr, _("newrole: incorrect password for %s\n"), pw.pw_name); send_audit_message(0, old_context, new_context, ttyn); goto err_close_pam; } /* * Step 3: Handle relabeling of the tty. * * Once we authenticate the user, we know that we want to proceed with * the action. Prior to this point, no changes are made the to system. */ fd = relabel_tty(ttyn, new_context, &tty_context, &new_tty_context); if (fd < 0) goto err_close_pam; /* * Step 4: Fork * * Fork, allowing parent to clean up after shell has executed. * Child: reopen stdin, stdout, stderr and exec shell * Parnet: wait for child to die and restore tty's context */ childPid = fork(); if (childPid < 0) { /* fork failed, no child to worry about */ int errsv = errno; fprintf(stderr, _("newrole: failure forking: %s"), strerror(errsv)); if (restore_tty_label(fd, ttyn, tty_context, new_tty_context)) fprintf(stderr, _("Unable to restore tty label...\n")); if (close(fd)) fprintf(stderr, _("Failed to close tty properly\n")); goto err_close_pam; } else if (childPid) { /* PARENT * It doesn't make senes to exit early on errors at this point, * since we are doing cleanup which needs to be done. * We can exit with a bad rc though */ pid_t pid; int exit_code = 0; int status; do { pid = wait(&status); } while (pid < 0 && errno == EINTR); /* Preserve child exit status, unless there is another error. */ if (WIFEXITED(status)) exit_code = WEXITSTATUS(status); if (restore_tty_label(fd, ttyn, tty_context, new_tty_context)) { fprintf(stderr, _("Unable to restore tty label...\n")); exit_code = -1; } freecon(tty_context); freecon(new_tty_context); if (close(fd)) { fprintf(stderr, _("Failed to close tty properly\n")); exit_code = -1; } #ifdef USE_PAM #ifdef NAMESPACE_PRIV pam_status = pam_close_session(pam_handle, 0); if (pam_status != PAM_SUCCESS) { fprintf(stderr, "pam_close_session failed with %s\n", pam_strerror(pam_handle, pam_status)); exit_code = -1; } #endif rc = pam_end(pam_handle, pam_status); if (rc != PAM_SUCCESS) { fprintf(stderr, "pam_end failed with %s\n", pam_strerror(pam_handle, rc)); exit_code = -1; } hashtab_map(app_service_names, free_hashtab_entry, NULL); hashtab_destroy(app_service_names); #endif free(pw.pw_name); free(pw.pw_dir); free(pw.pw_shell); free(shell_argv0); return exit_code; } /* CHILD */ /* Close the tty and reopen descriptors 0 through 2 */ if (ttyn) { if (close(fd) || close(0) || close(1) || close(2)) { fprintf(stderr, _("Could not close descriptors.\n")); goto err_close_pam; } fd = open(ttyn, O_RDONLY | O_NONBLOCK); if (fd != 0) goto err_close_pam; fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK); fd = open(ttyn, O_RDWR | O_NONBLOCK); if (fd != 1) goto err_close_pam; fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK); fd = open(ttyn, O_RDWR | O_NONBLOCK); if (fd != 2) goto err_close_pam; fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK); } /* * Step 5: Execute a new shell with the new context in `new_context'. * * Establish context, namesapce and any options for the new shell */ if (optind < 1) optind = 1; /* This is ugly, but use newrole's argv for the exec'd shells argv */ if (asprintf(&shell_argv0, "-%s", pw.pw_shell) < 0) { fprintf(stderr, _("Error allocating shell's argv0.\n")); shell_argv0 = NULL; goto err_close_pam; } argv[optind - 1] = shell_argv0; if (setexeccon(new_context)) { fprintf(stderr, _("Could not set exec context to %s.\n"), new_context); goto err_close_pam; } #ifdef NAMESPACE_PRIV /* Ask PAM to setup session for user running this program */ pam_status = pam_open_session(pam_handle, 0); if (pam_status != PAM_SUCCESS) { fprintf(stderr, "pam_open_session failed with %s\n", pam_strerror(pam_handle, pam_status)); goto err_close_pam; } #endif if (send_audit_message(1, old_context, new_context, ttyn)) goto err_close_pam_session; freecon(old_context); old_context=NULL; freecon(new_context); new_context=NULL; #ifdef NAMESPACE_PRIV if (transition_to_caller_uid()) goto err_close_pam_session; #endif if (drop_capabilities(TRUE)) goto err_close_pam_session; /* Handle environment changes */ if (restore_environment(preserve_environment, old_environ, &pw)) { fprintf(stderr, _("Unable to restore the environment, " "aborting\n")); goto err_close_pam_session; } execv(pw.pw_shell, argv + optind - 1); /* * Error path cleanup * * If we reach here, then we failed to exec the new shell. */ perror(_("failed to exec shell\n")); err_close_pam_session: #ifdef NAMESPACE_PRIV pam_status = pam_close_session(pam_handle, 0); if (pam_status != PAM_SUCCESS) fprintf(stderr, "pam_close_session failed with %s\n", pam_strerror(pam_handle, pam_status)); #endif err_close_pam: #ifdef USE_PAM rc = pam_end(pam_handle, pam_status); if (rc != PAM_SUCCESS) fprintf(stderr, "pam_end failed with %s\n", pam_strerror(pam_handle, rc)); #endif err_free: freecon(tty_context); freecon(new_tty_context); freecon(old_context); freecon(new_context); free(pw.pw_name); free(pw.pw_dir); free(pw.pw_shell); free(shell_argv0); #ifdef USE_PAM if (app_service_names) { hashtab_map(app_service_names, free_hashtab_entry, NULL); hashtab_destroy(app_service_names); } #endif return -1; } /* main() */