src/auth/password-scheme.c

	password-scheme.c revision 2e2b76ea4b5bc55ac4c2be33ee27070bfb95a093
/* Copyright (C) 2003 Timo Sirainen */

#include "lib.h"
#include "buffer.h"
#include "base64.h"
#include "hex-binary.h"
#include "md4.h"
#include "md5.h"
#include "module-dir.h"
#include "mycrypt.h"
#include "randgen.h"
#include "sha1.h"
#include "otp.h"
#include "str.h"
#include "password-scheme.h"

static const char salt_chars[] =
    "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

static buffer_t *schemes_buf;
static const struct password_scheme *schemes;
#ifdef HAVE_MODULES
static struct module *scheme_modules;
#endif

int password_verify(const char *plaintext, const char *password,
            const char *scheme, const char *user)
{
    const struct password_scheme *s;

    if (password == NULL)
        return 0;

    for (s = schemes; s->name != NULL; s++) {
        if (strcasecmp(s->name, scheme) == 0)
            return s->password_verify(plaintext, password, user);
    }

    return -1;
}

const char *password_list_schemes(const struct password_scheme **listptr)
{
    if (*listptr == NULL)
        *listptr = schemes;

    if ((*listptr)->name == NULL) {
        *listptr = NULL;
        return NULL;
    }

    return (*listptr)++->name;
}

bool password_scheme_is_alias(const char *scheme1, const char *scheme2)
{
    const struct password_scheme *s, *s1 = NULL, *s2 = NULL;

    if (strcasecmp(scheme1, scheme2) == 0)
        return TRUE;

    for (s = schemes; s->name != NULL; s++) {
        if (strcasecmp(s->name, scheme1) == 0)
            s1 = s;
        else if (strcasecmp(s->name, scheme2) == 0)
            s2 = s;
    }

    /* if they've the same verify function, they're equivalent */
    return s1 != NULL && s2 != NULL &&
        s1->password_verify == s2->password_verify;
}

const char *password_get_scheme(const char **password)
{
    const char *p, *scheme;

    if (*password == NULL)
        return NULL;

    if (strncmp(*password, "$1$", 3) == 0) {
        /* $1$<salt>$<password>[$<ignored>] */
        p = strchr(*password + 3, '$');
        if (p != NULL) {
            /* stop at next '$' after password */
            p = strchr(p+1, '$');
            if (p != NULL)
                *password = t_strdup_until(*password, p);
            return "MD5-CRYPT";
        }
    }

    if (**password != '{')
        return NULL;

    p = strchr(*password, '}');
    if (p == NULL)
        return NULL;

    scheme = t_strdup_until(*password + 1, p);
    *password = p + 1;
    return scheme;
}

const char *password_generate(const char *plaintext, const char *user,
                  const char *scheme)
{
    const struct password_scheme *s;

    for (s = schemes; s->name != NULL; s++) {
        if (strcasecmp(s->name, scheme) == 0)
            return s->password_generate(plaintext, user);
    }

    return NULL;
}

static bool crypt_verify(const char *plaintext, const char *password,
             const char *user __attr_unused__)
{
    return strcmp(mycrypt(plaintext, password), password) == 0;
}

static const char *crypt_generate(const char *plaintext,
                  const char *user __attr_unused__)
{
    char salt[9];

    random_fill(salt, 2);
    salt[0] = salt_chars[salt[0] % (sizeof(salt_chars)-1)];
    salt[1] = salt_chars[salt[1] % (sizeof(salt_chars)-1)];
    salt[2] = '\0';
    return t_strdup(mycrypt(plaintext, salt));
}

static bool md5_crypt_verify(const char *plaintext, const char *password,
                 const char *user __attr_unused__)
{
    const char *str;

    str = password_generate_md5_crypt(plaintext, password);
    return strcmp(str, password) == 0;
}

static const char *md5_crypt_generate(const char *plaintext,
                      const char *user __attr_unused__)
{
    char salt[9];
    int i;

    random_fill(salt, 8);
    for (i = 0; i < 8; i++)
        salt[i] = salt_chars[salt[i] % (sizeof(salt_chars)-1)];
    salt[8] = '\0';
    return password_generate_md5_crypt(plaintext, salt);
}

static const char *sha1_generate(const char *plaintext,
                const char *user __attr_unused__)
{
    unsigned char digest[SHA1_RESULTLEN];
    string_t *str;

    sha1_get_digest(plaintext, strlen(plaintext), digest);
    str = t_str_new(MAX_BASE64_ENCODED_SIZE(sizeof(digest)+1));
    base64_encode(digest, sizeof(digest), str);
    return str_c(str);
}

static const void *
password_decode(const char *password, unsigned int result_len)
{
    buffer_t *buf;
    size_t len;

    len = strlen(password);
    if (len == result_len*2) {
        /* hex-encoded */
        buf = buffer_create_static_hard(pool_datastack_create(),
                        result_len);

        if (hex_to_binary(password, buf) < 0)
            return NULL;
    } else {
        /* base64-encoded */
        buf = buffer_create_static_hard(pool_datastack_create(),
                        MAX_BASE64_DECODED_SIZE(len));

        if (base64_decode(password, len, NULL, buf) < 0)
            return NULL;
    }

    return buf->used != result_len ? NULL : buf->data;
}

static bool sha1_verify(const char *plaintext, const char *password,
            const char *user)
{
    unsigned char sha1_digest[SHA1_RESULTLEN];
    const char *data;

    sha1_get_digest(plaintext, strlen(plaintext), sha1_digest);

    data = password_decode(password, SHA1_RESULTLEN);
    if (data == NULL) {
        i_error("sha1_verify(%s): Invalid password encoding", user);
        return 0;
    }

    return memcmp(sha1_digest, data, SHA1_RESULTLEN) == 0;
}

static const char *ssha_generate(const char *plaintext,
                 const char *user __attr_unused__)
{
#define SSHA_SALT_LEN 4
    unsigned char ssha_digest[SHA1_RESULTLEN + SSHA_SALT_LEN];
    unsigned char *salt = &ssha_digest[SHA1_RESULTLEN];
    struct sha1_ctxt ctx;
    string_t *str;

    random_fill(salt, SSHA_SALT_LEN);

    sha1_init(&ctx);
    sha1_loop(&ctx, plaintext, strlen(plaintext));
    sha1_loop(&ctx, salt, SSHA_SALT_LEN);
    sha1_result(&ctx, ssha_digest);

    str = t_str_new(MAX_BASE64_ENCODED_SIZE(sizeof(ssha_digest))+1);
    base64_encode(ssha_digest, sizeof(ssha_digest), str);
    return str_c(str);
}

static bool ssha_verify(const char *plaintext, const char *password,
            const char *user __attr_unused__)
{
    unsigned char sha1_digest[SHA1_RESULTLEN];
    buffer_t *buf;
    const char *data;
    size_t size, password_len;
    struct sha1_ctxt ctx;

    /* format: base64-encoded MD5 hash and salt */
    password_len = strlen(password);
    buf = buffer_create_static_hard(pool_datastack_create(),
                    MAX_BASE64_DECODED_SIZE(password_len));

    if (base64_decode(password, password_len, NULL, buf) < 0) {
        i_error("ssha_verify(%s): failed decoding SSHA base64", user);
        return 0;
    }

    data = buffer_get_data(buf, &size);
    if (size <= SHA1_RESULTLEN) {
        i_error("ssha_verify(%s): invalid SSHA base64 decode", user);
        return 0;
    }

    sha1_init(&ctx);
    sha1_loop(&ctx, plaintext, strlen(plaintext));
    sha1_loop(&ctx, &data[SHA1_RESULTLEN], size-SHA1_RESULTLEN);
    sha1_result(&ctx, sha1_digest);
    return memcmp(sha1_digest, data, SHA1_RESULTLEN) == 0;
}

static const char *smd5_generate(const char *plaintext,
                 const char *user __attr_unused__)
{
#define SMD5_SALT_LEN 4
    unsigned char smd5_digest[MD5_RESULTLEN + SMD5_SALT_LEN];
    unsigned char *salt = &smd5_digest[MD5_RESULTLEN];
    struct md5_context ctx;
    string_t *str;

    random_fill(salt, SMD5_SALT_LEN);

    md5_init(&ctx);
    md5_update(&ctx, plaintext, strlen(plaintext));
    md5_update(&ctx, salt, SMD5_SALT_LEN);
    md5_final(&ctx, smd5_digest);

    str = t_str_new(MAX_BASE64_ENCODED_SIZE(sizeof(smd5_digest))+1);
    base64_encode(smd5_digest, sizeof(smd5_digest), str);
    return str_c(str);
}

static bool smd5_verify(const char *plaintext, const char *password,
            const char *user __attr_unused__)
{
    unsigned char md5_digest[MD5_RESULTLEN];
    buffer_t *buf;
    const char *data;
    size_t size, password_len;
    struct md5_context ctx;

    /* format: base64-encoded MD5 hash and salt */
    password_len = strlen(password);
    buf = buffer_create_static_hard(pool_datastack_create(),
                    MAX_BASE64_DECODED_SIZE(password_len));

    if (base64_decode(password, password_len, NULL, buf) < 0) {
        i_error("smd5_verify(%s): failed decoding SMD5 base64", user);
        return 0;
    }

    data = buffer_get_data(buf, &size);
    if (size <= MD5_RESULTLEN) {
        i_error("smd5_verify(%s): invalid SMD5 base64 decode", user);
        return 0;
    }

    md5_init(&ctx);
    md5_update(&ctx, plaintext, strlen(plaintext));
    md5_update(&ctx, &data[MD5_RESULTLEN], size-MD5_RESULTLEN);
    md5_final(&ctx, md5_digest);
    return memcmp(md5_digest, data, MD5_RESULTLEN) == 0;
}

static bool plain_verify(const char *plaintext, const char *password,
             const char *user __attr_unused__)
{
    return strcmp(password, plaintext) == 0;
}

static const char *plain_generate(const char *plaintext,
                  const char *user __attr_unused__)
{
    return plaintext;
}

static bool cram_md5_verify(const char *plaintext, const char *password,
                const char *user __attr_unused__)
{
    return strcmp(password_generate_cram_md5(plaintext), password) == 0;
}

static const char *cram_md5_generate(const char *plaintext,
                     const char *user __attr_unused__)
{
    return password_generate_cram_md5(plaintext);
}

static bool digest_md5_verify(const char *plaintext, const char *password,
                  const char *user)
{
    unsigned char digest[MD5_RESULTLEN];
    const char *realm, *str;

    /* user:realm:passwd */
    realm = strchr(user, '@');
    if (realm != NULL) realm++; else realm = "";

    str = t_strconcat(t_strcut(user, '@'), ":", realm,  ":",
              plaintext, NULL);
    md5_get_digest(str, strlen(str), digest);
    str = binary_to_hex(digest, sizeof(digest));

    return strcasecmp(str, password) == 0;
}

static const char *digest_md5_generate(const char *plaintext, const char *user)
{
    const char *realm, *str;
    unsigned char digest[MD5_RESULTLEN];

    if (user == NULL)
        i_fatal("digest_md5_generate(): username not given");

    /* user:realm:passwd */
    realm = strchr(user, '@');
    if (realm != NULL) realm++; else realm = "";

    str = t_strconcat(t_strcut(user, '@'), ":", realm,  ":",
              plaintext, NULL);
    md5_get_digest(str, strlen(str), digest);
    return binary_to_hex(digest, sizeof(digest));
}

static bool plain_md4_verify(const char *plaintext, const char *password,
                 const char *user)
{
    unsigned char digest[MD4_RESULTLEN];
    const void *data;

    md4_get_digest(plaintext, strlen(plaintext), digest);

    data = password_decode(password, MD4_RESULTLEN);
    if (data == NULL) {
        i_error("plain_md4_verify(%s): Invalid password encoding",
            user);
        return 0;
    }
    return memcmp(digest, data, MD4_RESULTLEN) == 0;
}

static const char *plain_md4_generate(const char *plaintext,
                      const char *user __attr_unused__)
{
    unsigned char digest[MD4_RESULTLEN];

    md4_get_digest(plaintext, strlen(plaintext), digest);
    return binary_to_hex(digest, sizeof(digest));
}

static bool plain_md5_verify(const char *plaintext, const char *password,
                 const char *user)
{
    unsigned char digest[MD5_RESULTLEN];
    const void *data;

    md5_get_digest(plaintext, strlen(plaintext), digest);

    data = password_decode(password, MD5_RESULTLEN);
    if (data == NULL) {
        i_error("plain_md5_verify(%s): Invalid password encoding",
            user);
        return 0;
    }
    return memcmp(digest, data, MD5_RESULTLEN) == 0;
}

static const char *plain_md5_generate(const char *plaintext,
                      const char *user __attr_unused__)
{
    unsigned char digest[MD5_RESULTLEN];

    md5_get_digest(plaintext, strlen(plaintext), digest);
    return binary_to_hex(digest, sizeof(digest));
}

static const char *ldap_md5_generate(const char *plaintext,
                     const char *user __attr_unused__)
{
    unsigned char digest[MD5_RESULTLEN];
    string_t *str;

    md5_get_digest(plaintext, strlen(plaintext), digest);
    str = t_str_new(MAX_BASE64_ENCODED_SIZE(sizeof(digest)+1));
    base64_encode(digest, sizeof(digest), str);
    return str_c(str);
}

static bool lm_verify(const char *plaintext, const char *password,
              const char *user __attr_unused__)
{
    return strcasecmp(password, password_generate_lm(plaintext)) == 0;
}

static const char *lm_generate(const char *plaintext,
                 const char *user __attr_unused__)
{
    return password_generate_lm(plaintext);
}

static bool ntlm_verify(const char *plaintext, const char *password,
            const char *user __attr_unused__)
{
    return strcasecmp(password, password_generate_ntlm(plaintext)) == 0;
}

static const char *ntlm_generate(const char *plaintext,
                 const char *user __attr_unused__)
{
    return password_generate_ntlm(plaintext);
}

static bool otp_verify(const char *plaintext, const char *password,
               const char *user __attr_unused__)
{
    return strcasecmp(password,
        password_generate_otp(plaintext, password, -1)) == 0;
}

static const char *otp_generate(const char *plaintext,
                const char *user __attr_unused__)
{
    return password_generate_otp(plaintext, NULL, OTP_HASH_SHA1);
}

static const char *skey_generate(const char *plaintext,
                 const char *user __attr_unused__)
{
    return password_generate_otp(plaintext, NULL, OTP_HASH_MD4);
}

static bool rpa_verify(const char *plaintext, const char *password,
               const char *user __attr_unused__)
{
    return strcasecmp(password, password_generate_rpa(plaintext)) == 0;
}

static const char *rpa_generate(const char *plaintext,
                const char *user __attr_unused__)
{
    return password_generate_rpa(plaintext);
}

static const struct password_scheme default_schemes[] = {
    { "CRYPT", crypt_verify, crypt_generate },
    { "MD5", md5_crypt_verify, md5_crypt_generate },
    { "MD5-CRYPT", md5_crypt_verify, md5_crypt_generate },
    { "SHA", sha1_verify, sha1_generate },
    { "SHA1", sha1_verify, sha1_generate },
    { "SMD5", smd5_verify, smd5_generate },
    { "SSHA", ssha_verify, ssha_generate },
    { "PLAIN", plain_verify, plain_generate },
    { "CLEARTEXT", plain_verify, plain_generate },
    { "CRAM-MD5", cram_md5_verify, cram_md5_generate },
    { "HMAC-MD5", cram_md5_verify, cram_md5_generate },
    { "DIGEST-MD5", digest_md5_verify, digest_md5_generate },
    { "PLAIN-MD4", plain_md4_verify, plain_md4_generate },
    { "PLAIN-MD5", plain_md5_verify, plain_md5_generate },
    { "LDAP-MD5", plain_md5_verify, ldap_md5_generate },
    { "LANMAN", lm_verify, lm_generate },
    { "NTLM", ntlm_verify, ntlm_generate },
    { "OTP", otp_verify, otp_generate },
    { "SKEY", otp_verify, skey_generate },
    { "RPA", rpa_verify, rpa_generate },
    { NULL, NULL, NULL }
};

void password_schemes_init(void)
{
    static const struct password_scheme null_scheme = { NULL, NULL, NULL };
    const struct password_scheme *s;
#ifdef HAVE_MODULES
    struct module *mod;
    const char *symbol;
#endif

    schemes_buf = buffer_create_dynamic(default_pool, 128);
    for (s = default_schemes; s->name != NULL; s++)
        buffer_append(schemes_buf, s, sizeof(*s));

#ifdef HAVE_MODULES
    scheme_modules = module_dir_load(AUTH_MODULE_DIR"/password",
                     NULL, FALSE, PACKAGE_VERSION);
    module_dir_init(scheme_modules);
    for (mod = scheme_modules; mod != NULL; mod = mod->next) {
        t_push();
        symbol = t_strconcat(mod->name, "_scheme", NULL);
        s = module_get_symbol(mod, symbol);
        if (s != NULL)
            buffer_append(schemes_buf, s, sizeof(*s));
        t_pop();
    }
#endif

    buffer_append(schemes_buf, &null_scheme, sizeof(null_scheme));
    schemes = buffer_get_data(schemes_buf, NULL);
}

void password_schemes_deinit(void)
{
#ifdef HAVE_MODULES
    module_dir_unload(&scheme_modules);
#endif

    buffer_free(schemes_buf);
    schemes = NULL;
}