diff options
Diffstat (limited to 'modules/pam_faillock/pam_faillock.c')
| -rw-r--r-- | modules/pam_faillock/pam_faillock.c | 764 |
1 files changed, 764 insertions, 0 deletions
diff --git a/modules/pam_faillock/pam_faillock.c b/modules/pam_faillock/pam_faillock.c new file mode 100644 index 0000000..8328fba --- /dev/null +++ b/modules/pam_faillock/pam_faillock.c @@ -0,0 +1,764 @@ +/* + * Copyright (c) 2010, 2017, 2019 Tomas Mraz <tmraz@redhat.com> + * Copyright (c) 2010, 2017, 2019 Red Hat, Inc. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, and the entire permission notice in its entirety, + * including the disclaimer of warranties. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote + * products derived from this software without specific prior + * written permission. + * + * ALTERNATIVELY, this product may be distributed under the terms of + * the GNU Public License, in which case the provisions of the GPL are + * required INSTEAD OF the above restrictions. (This clause is + * necessary due to a potential bad interaction between the GPL and + * the restrictions contained in a BSD-style copyright.) + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, + * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR + * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED + * OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "config.h" +#include <stdio.h> +#include <string.h> +#include <unistd.h> +#include <stdint.h> +#include <stdlib.h> +#include <errno.h> +#include <time.h> +#include <pwd.h> +#include <syslog.h> +#include <ctype.h> + +#ifdef HAVE_LIBAUDIT +#include <libaudit.h> +#endif + +#include <security/pam_modules.h> +#include <security/pam_modutil.h> +#include <security/pam_ext.h> + +#include "pam_inline.h" +#include "faillock.h" + +#define FAILLOCK_ACTION_PREAUTH 0 +#define FAILLOCK_ACTION_AUTHSUCC 1 +#define FAILLOCK_ACTION_AUTHFAIL 2 + +#define FAILLOCK_FLAG_DENY_ROOT 0x1 +#define FAILLOCK_FLAG_AUDIT 0x2 +#define FAILLOCK_FLAG_SILENT 0x4 +#define FAILLOCK_FLAG_NO_LOG_INFO 0x8 +#define FAILLOCK_FLAG_UNLOCKED 0x10 +#define FAILLOCK_FLAG_LOCAL_ONLY 0x20 +#define FAILLOCK_FLAG_NO_DELAY 0x40 + +#define MAX_TIME_INTERVAL 604800 /* 7 days */ +#define FAILLOCK_CONF_MAX_LINELEN 1023 + +static const char default_faillock_conf[] = FAILLOCK_DEFAULT_CONF; + +struct options { + unsigned int action; + unsigned int flags; + unsigned short deny; + unsigned int fail_interval; + unsigned int unlock_time; + unsigned int root_unlock_time; + char *dir; + const char *user; + char *admin_group; + int failures; + uint64_t latest_time; + uid_t uid; + int is_admin; + uint64_t now; + int fatal_error; +}; + +static int read_config_file( + pam_handle_t *pamh, + struct options *opts, + const char *cfgfile +); + +static void set_conf_opt( + pam_handle_t *pamh, + struct options *opts, + const char *name, + const char *value +); + +static int +args_parse(pam_handle_t *pamh, int argc, const char **argv, + int flags, struct options *opts) +{ + int i; + int config_arg_index = -1; + int rv; + const char *conf = default_faillock_conf; + + memset(opts, 0, sizeof(*opts)); + + opts->dir = strdup(FAILLOCK_DEFAULT_TALLYDIR); + opts->deny = 3; + opts->fail_interval = 900; + opts->unlock_time = 600; + opts->root_unlock_time = MAX_TIME_INTERVAL+1; + + for (i = 0; i < argc; ++i) { + const char *str = pam_str_skip_prefix(argv[i], "conf="); + + if (str != NULL) { + conf = str; + config_arg_index = i; + } + } + + if ((rv = read_config_file(pamh, opts, conf)) != PAM_SUCCESS) { + pam_syslog(pamh, LOG_ERR, + "Configuration file missing or broken"); + return rv; + } + + for (i = 0; i < argc; ++i) { + if (i == config_arg_index) { + continue; + } + else if (strcmp(argv[i], "preauth") == 0) { + opts->action = FAILLOCK_ACTION_PREAUTH; + } + else if (strcmp(argv[i], "authfail") == 0) { + opts->action = FAILLOCK_ACTION_AUTHFAIL; + } + else if (strcmp(argv[i], "authsucc") == 0) { + opts->action = FAILLOCK_ACTION_AUTHSUCC; + } + else { + char buf[FAILLOCK_CONF_MAX_LINELEN + 1]; + char *val; + + strncpy(buf, argv[i], sizeof(buf) - 1); + buf[sizeof(buf) - 1] = '\0'; + + val = strchr(buf, '='); + if (val != NULL) { + *val = '\0'; + ++val; + } + else { + val = buf + sizeof(buf) - 1; + } + set_conf_opt(pamh, opts, buf, val); + } + } + + if (opts->root_unlock_time == MAX_TIME_INTERVAL+1) + opts->root_unlock_time = opts->unlock_time; + if (flags & PAM_SILENT) + opts->flags |= FAILLOCK_FLAG_SILENT; + + if (opts->dir == NULL) { + pam_syslog(pamh, LOG_CRIT, "Error allocating memory: %m"); + opts->fatal_error = 1; + } + + if (opts->fatal_error) + return PAM_BUF_ERR; + return PAM_SUCCESS; +} + +/* parse a single configuration file */ +static int +read_config_file(pam_handle_t *pamh, struct options *opts, const char *cfgfile) +{ + FILE *f; + char linebuf[FAILLOCK_CONF_MAX_LINELEN+1]; + + f = fopen(cfgfile, "r"); + if (f == NULL) { + /* ignore non-existent default config file */ + if (errno == ENOENT && cfgfile == default_faillock_conf) + return PAM_SUCCESS; + return PAM_SERVICE_ERR; + } + + while (fgets(linebuf, sizeof(linebuf), f) != NULL) { + size_t len; + char *ptr; + char *name; + int eq; + + len = strlen(linebuf); + /* len cannot be 0 unless there is a bug in fgets */ + if (len && linebuf[len - 1] != '\n' && !feof(f)) { + (void) fclose(f); + return PAM_SERVICE_ERR; + } + + if ((ptr=strchr(linebuf, '#')) != NULL) { + *ptr = '\0'; + } else { + ptr = linebuf + len; + } + + /* drop terminating whitespace including the \n */ + while (ptr > linebuf) { + if (!isspace(*(ptr-1))) { + *ptr = '\0'; + break; + } + --ptr; + } + + /* skip initial whitespace */ + for (ptr = linebuf; isspace(*ptr); ptr++); + if (*ptr == '\0') + continue; + + /* grab the key name */ + eq = 0; + name = ptr; + while (*ptr != '\0') { + if (isspace(*ptr) || *ptr == '=') { + eq = *ptr == '='; + *ptr = '\0'; + ++ptr; + break; + } + ++ptr; + } + + /* grab the key value */ + while (*ptr != '\0') { + if (*ptr != '=' || eq) { + if (!isspace(*ptr)) { + break; + } + } else { + eq = 1; + } + ++ptr; + } + + /* set the key:value pair on opts */ + set_conf_opt(pamh, opts, name, ptr); + } + + (void)fclose(f); + return PAM_SUCCESS; +} + +static void +set_conf_opt(pam_handle_t *pamh, struct options *opts, const char *name, const char *value) +{ + if (strcmp(name, "dir") == 0) { + if (value[0] != '/') { + pam_syslog(pamh, LOG_ERR, + "Tally directory is not absolute path (%s); keeping default", value); + } else { + free(opts->dir); + opts->dir = strdup(value); + } + } + else if (strcmp(name, "deny") == 0) { + if (sscanf(value, "%hu", &opts->deny) != 1) { + pam_syslog(pamh, LOG_ERR, + "Bad number supplied for deny argument"); + } + } + else if (strcmp(name, "fail_interval") == 0) { + unsigned int temp; + if (sscanf(value, "%u", &temp) != 1 || + temp > MAX_TIME_INTERVAL) { + pam_syslog(pamh, LOG_ERR, + "Bad number supplied for fail_interval argument"); + } else { + opts->fail_interval = temp; + } + } + else if (strcmp(name, "unlock_time") == 0) { + unsigned int temp; + + if (strcmp(value, "never") == 0) { + opts->unlock_time = 0; + } + else if (sscanf(value, "%u", &temp) != 1 || + temp > MAX_TIME_INTERVAL) { + pam_syslog(pamh, LOG_ERR, + "Bad number supplied for unlock_time argument"); + } + else { + opts->unlock_time = temp; + } + } + else if (strcmp(name, "root_unlock_time") == 0) { + unsigned int temp; + + if (strcmp(value, "never") == 0) { + opts->root_unlock_time = 0; + } + else if (sscanf(value, "%u", &temp) != 1 || + temp > MAX_TIME_INTERVAL) { + pam_syslog(pamh, LOG_ERR, + "Bad number supplied for root_unlock_time argument"); + } else { + opts->root_unlock_time = temp; + } + } + else if (strcmp(name, "admin_group") == 0) { + free(opts->admin_group); + opts->admin_group = strdup(value); + if (opts->admin_group == NULL) { + opts->fatal_error = 1; + pam_syslog(pamh, LOG_CRIT, "Error allocating memory: %m"); + } + } + else if (strcmp(name, "even_deny_root") == 0) { + opts->flags |= FAILLOCK_FLAG_DENY_ROOT; + } + else if (strcmp(name, "audit") == 0) { + opts->flags |= FAILLOCK_FLAG_AUDIT; + } + else if (strcmp(name, "silent") == 0) { + opts->flags |= FAILLOCK_FLAG_SILENT; + } + else if (strcmp(name, "no_log_info") == 0) { + opts->flags |= FAILLOCK_FLAG_NO_LOG_INFO; + } + else if (strcmp(name, "local_users_only") == 0) { + opts->flags |= FAILLOCK_FLAG_LOCAL_ONLY; + } + else if (strcmp(name, "nodelay") == 0) { + opts->flags |= FAILLOCK_FLAG_NO_DELAY; + } + else { + pam_syslog(pamh, LOG_ERR, "Unknown option: %s", name); + } +} + +static int +check_local_user (pam_handle_t *pamh, const char *user) +{ + return pam_modutil_check_user_in_passwd(pamh, user, NULL) == PAM_SUCCESS; +} + +static int +get_pam_user(pam_handle_t *pamh, struct options *opts) +{ + const char *user; + int rv; + struct passwd *pwd; + + if ((rv=pam_get_user(pamh, &user, NULL)) != PAM_SUCCESS) { + return rv == PAM_CONV_AGAIN ? PAM_INCOMPLETE : rv; + } + + if (*user == '\0') { + return PAM_IGNORE; + } + + if ((pwd=pam_modutil_getpwnam(pamh, user)) == NULL) { + if (opts->flags & FAILLOCK_FLAG_AUDIT) { + pam_syslog(pamh, LOG_NOTICE, "User unknown: %s", user); + } + else { + pam_syslog(pamh, LOG_NOTICE, "User unknown"); + } + return PAM_IGNORE; + } + opts->user = user; + opts->uid = pwd->pw_uid; + + if (pwd->pw_uid == 0) { + opts->is_admin = 1; + return PAM_SUCCESS; + } + + if (opts->admin_group && *opts->admin_group) { + opts->is_admin = pam_modutil_user_in_group_uid_nam(pamh, + pwd->pw_uid, opts->admin_group); + } + + return PAM_SUCCESS; +} + +static int +check_tally(pam_handle_t *pamh, struct options *opts, struct tally_data *tallies, int *fd) +{ + int tfd; + unsigned int i; + uint64_t latest_time; + int failures; + + opts->now = time(NULL); + + tfd = open_tally(opts->dir, opts->user, opts->uid, 0); + + *fd = tfd; + + if (tfd == -1) { + if (errno == EACCES || errno == ENOENT) { + return PAM_SUCCESS; + } + pam_syslog(pamh, LOG_ERR, "Error opening the tally file for %s: %m", opts->user); + return PAM_SYSTEM_ERR; + } + + if (read_tally(tfd, tallies) != 0) { + pam_syslog(pamh, LOG_ERR, "Error reading the tally file for %s: %m", opts->user); + return PAM_SYSTEM_ERR; + } + + if (opts->is_admin && !(opts->flags & FAILLOCK_FLAG_DENY_ROOT)) { + return PAM_SUCCESS; + } + + latest_time = 0; + for (i = 0; i < tallies->count; i++) { + if ((tallies->records[i].status & TALLY_STATUS_VALID) && + tallies->records[i].time > latest_time) + latest_time = tallies->records[i].time; + } + + opts->latest_time = latest_time; + + failures = 0; + for (i = 0; i < tallies->count; i++) { + if ((tallies->records[i].status & TALLY_STATUS_VALID) && + latest_time - tallies->records[i].time < opts->fail_interval) { + ++failures; + } + } + + opts->failures = failures; + + if (opts->deny && failures >= opts->deny) { + if ((!opts->is_admin && opts->unlock_time && latest_time + opts->unlock_time < opts->now) || + (opts->is_admin && opts->root_unlock_time && latest_time + opts->root_unlock_time < opts->now)) { +#ifdef HAVE_LIBAUDIT + if (opts->action != FAILLOCK_ACTION_PREAUTH) { /* do not audit in preauth */ + char buf[64]; + int audit_fd; + const void *rhost = NULL, *tty = NULL; + + audit_fd = audit_open(); + /* If there is an error & audit support is in the kernel report error */ + if ((audit_fd < 0) && !(errno == EINVAL || errno == EPROTONOSUPPORT || + errno == EAFNOSUPPORT)) + return PAM_SYSTEM_ERR; + + (void)pam_get_item(pamh, PAM_TTY, &tty); + (void)pam_get_item(pamh, PAM_RHOST, &rhost); + snprintf(buf, sizeof(buf), "pam_faillock uid=%u ", opts->uid); + audit_log_user_message(audit_fd, AUDIT_RESP_ACCT_UNLOCK_TIMED, buf, + rhost, NULL, tty, 1); + } +#endif + opts->flags |= FAILLOCK_FLAG_UNLOCKED; + return PAM_SUCCESS; + } + return PAM_AUTH_ERR; + } + return PAM_SUCCESS; +} + +static void +reset_tally(pam_handle_t *pamh, struct options *opts, int *fd) +{ + int rv; + + if (*fd == -1) { + *fd = open_tally(opts->dir, opts->user, opts->uid, 1); + } + else { + while ((rv=ftruncate(*fd, 0)) == -1 && errno == EINTR); + if (rv == -1) { + pam_syslog(pamh, LOG_ERR, "Error clearing the tally file for %s: %m", opts->user); + } + } +} + +static int +write_tally(pam_handle_t *pamh, struct options *opts, struct tally_data *tallies, int *fd) +{ + struct tally *records; + unsigned int i; + int failures; + unsigned int oldest; + uint64_t oldtime; + const void *source = NULL; + + if (*fd == -1) { + *fd = open_tally(opts->dir, opts->user, opts->uid, 1); + } + if (*fd == -1) { + if (errno == EACCES) { + return PAM_SUCCESS; + } + pam_syslog(pamh, LOG_ERR, "Error opening the tally file for %s: %m", opts->user); + return PAM_SYSTEM_ERR; + } + + oldtime = 0; + oldest = 0; + failures = 0; + + for (i = 0; i < tallies->count; ++i) { + if (oldtime == 0 || tallies->records[i].time < oldtime) { + oldtime = tallies->records[i].time; + oldest = i; + } + if (opts->flags & FAILLOCK_FLAG_UNLOCKED || + opts->now - tallies->records[i].time >= opts->fail_interval ) { + tallies->records[i].status &= ~TALLY_STATUS_VALID; + } else { + ++failures; + } + } + + if (oldest >= tallies->count || (tallies->records[oldest].status & TALLY_STATUS_VALID)) { + oldest = tallies->count; + + if ((records=realloc(tallies->records, (oldest+1) * sizeof (*tallies->records))) == NULL) { + pam_syslog(pamh, LOG_CRIT, "Error allocating memory for tally records: %m"); + return PAM_BUF_ERR; + } + + ++tallies->count; + tallies->records = records; + } + + memset(&tallies->records[oldest], 0, sizeof (*tallies->records)); + + tallies->records[oldest].status = TALLY_STATUS_VALID; + if (pam_get_item(pamh, PAM_RHOST, &source) != PAM_SUCCESS || source == NULL) { + if (pam_get_item(pamh, PAM_TTY, &source) != PAM_SUCCESS || source == NULL) { + if (pam_get_item(pamh, PAM_SERVICE, &source) != PAM_SUCCESS || source == NULL) { + source = ""; + } + } + else { + tallies->records[oldest].status |= TALLY_STATUS_TTY; + } + } + else { + tallies->records[oldest].status |= TALLY_STATUS_RHOST; + } + + strncpy(tallies->records[oldest].source, source, sizeof(tallies->records[oldest].source)); + /* source does not have to be null terminated */ + + tallies->records[oldest].time = opts->now; + + ++failures; + + if (opts->deny && failures == opts->deny) { +#ifdef HAVE_LIBAUDIT + char buf[64]; + int audit_fd; + + audit_fd = audit_open(); + /* If there is an error & audit support is in the kernel report error */ + if ((audit_fd < 0) && !(errno == EINVAL || errno == EPROTONOSUPPORT || + errno == EAFNOSUPPORT)) + return PAM_SYSTEM_ERR; + + snprintf(buf, sizeof(buf), "pam_faillock uid=%u ", opts->uid); + audit_log_user_message(audit_fd, AUDIT_ANOM_LOGIN_FAILURES, buf, + NULL, NULL, NULL, 1); + + if (!opts->is_admin || (opts->flags & FAILLOCK_FLAG_DENY_ROOT)) { + audit_log_user_message(audit_fd, AUDIT_RESP_ACCT_LOCK, buf, + NULL, NULL, NULL, 1); + } + close(audit_fd); +#endif + if (!(opts->flags & FAILLOCK_FLAG_NO_LOG_INFO)) { + pam_syslog(pamh, LOG_INFO, "Consecutive login failures for user %s account temporarily locked", + opts->user); + } + } + + if (update_tally(*fd, tallies) == 0) + return PAM_SUCCESS; + + return PAM_SYSTEM_ERR; +} + +static void +faillock_message(pam_handle_t *pamh, struct options *opts) +{ + int64_t left; + + if (!(opts->flags & FAILLOCK_FLAG_SILENT)) { + if (opts->is_admin) { + left = opts->latest_time + opts->root_unlock_time - opts->now; + } + else { + left = opts->latest_time + opts->unlock_time - opts->now; + } + + pam_info(pamh, _("The account is locked due to %u failed logins."), + (unsigned int)opts->failures); + if (left > 0) { + left = (left + 59)/60; /* minutes */ + +#if defined HAVE_DNGETTEXT && defined ENABLE_NLS + pam_info( + pamh, + dngettext(PACKAGE, + "(%d minute left to unlock)", + "(%d minutes left to unlock)", + (int)left), + (int)left); +#else + if (left == 1) + pam_info(pamh, _("(%d minute left to unlock)"), (int)left); + else + /* TRANSLATORS: only used if dngettext is not supported. */ + pam_info(pamh, _("(%d minutes left to unlock)"), (int)left); +#endif + } + } +} + +static void +tally_cleanup(struct tally_data *tallies, int fd) +{ + if (fd != -1) { + close(fd); + } + + free(tallies->records); +} + +static void +opts_cleanup(struct options *opts) +{ + free(opts->dir); + free(opts->admin_group); +} + +/*---------------------------------------------------------------------*/ + +int +pam_sm_authenticate(pam_handle_t *pamh, int flags, + int argc, const char **argv) +{ + struct options opts; + int rv, fd = -1; + struct tally_data tallies; + + memset(&tallies, 0, sizeof(tallies)); + + rv = args_parse(pamh, argc, argv, flags, &opts); + if (rv != PAM_SUCCESS) + goto err; + + if (!(opts.flags & FAILLOCK_FLAG_NO_DELAY)) { + pam_fail_delay(pamh, 2000000); /* 2 sec delay on failure */ + } + + if ((rv=get_pam_user(pamh, &opts)) != PAM_SUCCESS) { + goto err; + } + + if (!(opts.flags & FAILLOCK_FLAG_LOCAL_ONLY) || + check_local_user (pamh, opts.user) != 0) { + switch (opts.action) { + case FAILLOCK_ACTION_PREAUTH: + rv = check_tally(pamh, &opts, &tallies, &fd); + if (rv == PAM_AUTH_ERR && !(opts.flags & FAILLOCK_FLAG_SILENT)) { + faillock_message(pamh, &opts); + } + break; + + case FAILLOCK_ACTION_AUTHSUCC: + rv = check_tally(pamh, &opts, &tallies, &fd); + if (rv == PAM_SUCCESS) { + reset_tally(pamh, &opts, &fd); + } + break; + + case FAILLOCK_ACTION_AUTHFAIL: + rv = check_tally(pamh, &opts, &tallies, &fd); + if (rv == PAM_SUCCESS) { + rv = PAM_IGNORE; /* this return value should be ignored */ + write_tally(pamh, &opts, &tallies, &fd); + } + break; + } + } + + tally_cleanup(&tallies, fd); + +err: + opts_cleanup(&opts); + + return rv; +} + +/*---------------------------------------------------------------------*/ + +int +pam_sm_setcred(pam_handle_t *pamh UNUSED, int flags UNUSED, + int argc UNUSED, const char **argv UNUSED) +{ + return PAM_SUCCESS; +} + +/*---------------------------------------------------------------------*/ + +int +pam_sm_acct_mgmt(pam_handle_t *pamh, int flags, + int argc, const char **argv) +{ + struct options opts; + int rv, fd = -1; + struct tally_data tallies; + + memset(&tallies, 0, sizeof(tallies)); + + rv = args_parse(pamh, argc, argv, flags, &opts); + + if (rv != PAM_SUCCESS) + goto err; + + opts.action = FAILLOCK_ACTION_AUTHSUCC; + + if ((rv=get_pam_user(pamh, &opts)) != PAM_SUCCESS) { + goto err; + } + + if (!(opts.flags & FAILLOCK_FLAG_LOCAL_ONLY) || + check_local_user (pamh, opts.user) != 0) { + check_tally(pamh, &opts, &tallies, &fd); /* for auditing */ + reset_tally(pamh, &opts, &fd); + } + + tally_cleanup(&tallies, fd); + +err: + opts_cleanup(&opts); + + return rv; +} + +/*-----------------------------------------------------------------------*/ |