lib/util.c

/*
 * util.c
 *
 * Copyright (c) 2013 Duo Security
 * All rights reserved, all wrongs reversed
 */
#include "config.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <ctype.h>

#include "util.h"
#include "groupaccess.h"

int duo_debug = 0;

void
duo_config_default(struct duo_config *cfg)
{
    memset(cfg, 0, sizeof(struct duo_config));
    cfg->failmode = DUO_FAIL_SAFE;
    cfg->prompts = MAX_PROMPTS;
    cfg->local_ip_fallback = 0;
    cfg->https_timeout = -1;
    cfg->fips_mode = 0;
    cfg->gecos_username_pos = -1;
    cfg->gecos_delim = ',';
}

int
duo_set_boolean_option(const char *val)
{
    if (strcmp(val, "yes") == 0 || strcmp(val, "true") == 0 ||
        strcmp(val, "on") == 0 || strcmp(val, "1") == 0) {
        return (1);
    } else {
        return (0);
    }
}

int
duo_common_ini_handler(struct duo_config *cfg, const char *section,
    const char *name, const char*val)
{
    char *buf, *p;
    int int_val;

    if (strcmp(name, "ikey") == 0) {
        cfg->ikey = strdup(val);
    } else if (strcmp(name, "skey") == 0) {
        cfg->skey = strdup(val);
    } else if (strcmp(name, "host") == 0) {
        cfg->apihost = strdup(val);
    } else if (strcmp(name, "cafile") == 0) {
        cfg->cafile = strdup(val);
    } else if (strcmp(name, "http_proxy") == 0) {
        cfg->http_proxy = strdup(val);
    } else if (strcmp(name, "groups") == 0 || strcmp(name, "group") == 0) {
        if ((buf = strdup(val)) == NULL) {
            fprintf(stderr, "Out of memory parsing groups\n");
            return (0);
        }
        for (p = strtok(buf, " "); p != NULL; p = strtok(NULL, " ")) {
            if (cfg->groups_cnt >= MAX_GROUPS) {
                fprintf(stderr, "Exceeded max %d groups\n",
                    MAX_GROUPS);
                cfg->groups_cnt = 0;
                free(buf);
                return (0);
            }
            cfg->groups[cfg->groups_cnt++] = p;
        }
    } else if (strcmp(name, "failmode") == 0) {
        if (strcmp(val, "secure") == 0) {
            cfg->failmode = DUO_FAIL_SECURE;
        } else if (strcmp(val, "safe") == 0) {
            cfg->failmode = DUO_FAIL_SAFE;
        } else {
            fprintf(stderr, "Invalid failmode: '%s'\n", val);
            return (0);
        }
    } else if (strcmp(name, "pushinfo") == 0) {
        cfg->pushinfo = duo_set_boolean_option(val);
    } else if (strcmp(name, "noverify") == 0) {
        cfg->noverify = duo_set_boolean_option(val);
    } else if (strcmp(name, "prompts") == 0) {
        int_val = atoi(val);
        /* Clamp the value into acceptable range */
        if (int_val <= 0) {
            int_val = 1;
        } else if (int_val < cfg->prompts) {
            cfg->prompts = int_val;
        }
    } else if (strcmp(name, "autopush") == 0) {
        cfg->autopush = duo_set_boolean_option(val);
    } else if (strcmp(name, "accept_env_factor") == 0) {
        cfg->accept_env = duo_set_boolean_option(val);
    } else if (strcmp(name, "fallback_local_ip") == 0) {
        cfg->local_ip_fallback = duo_set_boolean_option(val);
    } else if (strcmp(name, "https_timeout") == 0) {
        cfg->https_timeout = atoi(val);
        if (cfg->https_timeout <= 0) {
            cfg->https_timeout = -1; /* no timeout */
        } else {
            /* Make timeout milliseconds */
            cfg->https_timeout *= 1000;
        }
    } else if (strcmp(name, "send_gecos") == 0) {
        cfg->send_gecos = duo_set_boolean_option(val);
    } else if (strcmp(name, "gecos_parsed") == 0) {
        duo_log(LOG_ERR, "The gecos_parsed configuration item for Duo Unix is deprecated and no longer has any effect. Use gecos_delim and gecos_username_pos instead", NULL, NULL, NULL);
    } else if (strcmp(name, "gecos_delim") == 0) {
        if (strlen(val) != 1) {
            fprintf(stderr, "Invalid character option length. Character fields must be 1 character long: '%s'\n", val);
            return (0);
        }

        char delim = val[0];
        if (!ispunct(delim) || delim == ':') {
            fprintf(stderr, "Invalid gecos_delim '%c' (delimiter must be punctuation other than ':')\n", delim);
            return (0);
        }
        cfg->gecos_delim = delim;
    } else if (strcmp(name, "gecos_username_pos") == 0) {
        int gecos_username_pos = atoi(val);
        if (gecos_username_pos < 1) {
            fprintf(stderr, "Gecos position starts at 1\n");
            return (0);
        }
        else {
            // Offset the position so user facing first position is 1
            cfg->gecos_username_pos = gecos_username_pos - 1;
        }
    } else if (strcmp(name, "dev_fips_mode") == 0) {
        /* This flag is for development */
        cfg->fips_mode = duo_set_boolean_option(val);
    } else {
        /* Couldn't handle the option, maybe it's target specific? */
        return (0);
    }
    return (1);
}

void
close_config(struct duo_config *cfg)
{
    if (cfg == NULL) {
        return;
    }
    if (cfg->ikey != NULL) {
        duo_zero_free(cfg->ikey, strlen(cfg->ikey));
        cfg->ikey = NULL;
    }
    if (cfg->skey != NULL) {
        duo_zero_free(cfg->skey, strlen(cfg->skey));
        cfg->skey = NULL;
    }
    if (cfg->apihost != NULL) {
        duo_zero_free(cfg->apihost, strlen(cfg->apihost));
        cfg->apihost = NULL;
    }
    if (cfg->cafile != NULL) {
        duo_zero_free(cfg->cafile, strlen(cfg->cafile));
        cfg->cafile = NULL;
    }
    if (cfg->http_proxy != NULL) {
        duo_zero_free(cfg->http_proxy, strlen(cfg->http_proxy));
        cfg->http_proxy = NULL;
    }
}

int
duo_check_groups(struct passwd *pw, char **groups, int groups_cnt)
{
    int i;

    if (groups_cnt > 0) {
        int matched = 0;

        if (ga_init(pw->pw_name, pw->pw_gid) < 0) {
            duo_log(LOG_ERR, "Couldn't get groups",
                pw->pw_name, NULL, strerror(errno));
            return (-1);
        }
        for (i = 0; i < groups_cnt; i++) {
            if (ga_match_pattern_list(groups[i])) {
                matched = 1;
                break;
            }
        }
        ga_free();

        /* User in configured groups for Duo auth? */
        return matched;
    } else {
        return 1;
    }
}

void
duo_log(int priority, const char*msg, const char *user, const char *ip,
        const char *err)
{
    char buf[512];
    int i, n;

    n = snprintf(buf, sizeof(buf), "%s", msg);

    if (user != NULL &&
        (i = snprintf(buf + n, sizeof(buf) - n, " for '%s'", user)) > 0) {
        n += i;
    }
    if (ip != NULL &&
        (i = snprintf(buf + n, sizeof(buf) - n, " from %s", ip)) > 0) {
        n += i;
    }
    if (err != NULL &&
        (i = snprintf(buf + n, sizeof(buf) - n, ": %s", err)) > 0) {
        n += i;
    }
    duo_syslog(priority, "%s", buf);
}

void
duo_syslog(int priority, const char *fmt, ...)
{
    va_list ap;

    va_start(ap, fmt);
    if (duo_debug) {
        fprintf(stderr, "[%d] ", priority);
        vfprintf(stderr, fmt, ap);
        fputs("\n", stderr);
    } else {
        vsyslog(priority, fmt, ap);
    }
    va_end(ap);
}

const char *
duo_local_ip()
{
    struct sockaddr_in sin;
    socklen_t slen;
    int fd;
    const char *ip = NULL;

    memset(&sin, 0, sizeof(sin));
    sin.sin_family = AF_INET;
    sin.sin_addr.s_addr = inet_addr("8.8.8.8"); /* XXX Google's DNS Server */
    sin.sin_port = htons(53);
    slen = sizeof(sin);

    if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) != -1) {
        if (connect(fd, (struct sockaddr *)&sin, slen) != -1 &&
            getsockname(fd, (struct sockaddr *)&sin, &slen) != -1) {
            ip = inet_ntoa(sin.sin_addr); /* XXX statically allocated */
        }
        close(fd);
    }
    return (ip);
}

char *
duo_split_at(char *s, char delimiter, unsigned int position)
{
    unsigned int count = 0;
    char *iter = NULL;
    char *result = s;

    for (iter = s; *iter; iter++) {
        if (*iter == delimiter) {
            if (count < position) {
                result = iter + 1;
                count++;
            }
            *iter = '\0';
        }
    }

    if (count < position) {
        return NULL;
    }

    return result;
}

void
duo_zero_free(void *ptr, size_t size)
{
    /*
     * A compiler's usage of dead store optimization may skip the memory
     * zeroing if it doesn't detect futher usage. Different systems use explicit
     * zeroing functions to prevent this. If none of those are available we fall back
     * on volatile pointers to prevent optimization. There is no guarantee in the standard
     * that this will work, but gcc and other major compilers will respect it.
     * Idea and technique borrowed from https://github.com/openssh/openssh-portable
     */
    if (ptr != NULL) {
#ifdef HAVE_EXPLICIT_BZERO
        explicit_bzero(ptr, size);
#elif HAVE_MEMSET_S
        (void)memset_s(ptr, size, 0, size);
#else
        static void* (* volatile duo_memset)(void *, int, size_t) = memset;
        duo_memset(ptr, 0, size);
#endif
        free(ptr);
    }
}