src/auth/password-scheme.c

	password-scheme.c revision 21be4f711d3bab82a783273189a8bbca44a84c5d
/* Copyright (C) 2003 Timo Sirainen */

#include "lib.h"
#include "buffer.h"
#include "base64.h"
#include "hex-binary.h"
#include "md5.h"
#include "module-dir.h"
#include "mycrypt.h"
#include "randgen.h"
#include "sha1.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;
}

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

    if (*password == NULL)
        return NULL;

    if (strncmp(*password, "$1$", 3) == 0) {
        /* skip the salt */
        p = strchr(*password + 3, '$');
        if (p != NULL) {
            /* stop at next '$' */
            p = strchr(p+1, '$');
            if (p != NULL)
                *password = t_strdup_until(*password, p);
            return "MD5";
        }
    }

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

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

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

    /* LDAP's RFC2307 specifies the MD5 scheme for what we call PLAIN-MD5,
       only base64-encoded rather than hex-encoded.
       We can detect this case - base64 doesn't use '$'. */
    if (strncasecmp(scheme, "MD5", 3) == 0 &&
        strncmp(*password, "$1$", 3) != 0) {
        scheme = "LDAP-MD5";
    }
    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 int 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 int md5_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_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 int sha1_verify(const char *plaintext, const char *password,
              const char *user __attr_unused__)
{
    unsigned char sha1_digest[SHA1_RESULTLEN];
    const char *data;
    buffer_t *buf;
    size_t size;

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

    buf = buffer_create_static(pool_datastack_create(),
                   MAX_BASE64_DECODED_SIZE(strlen(password)+1));

    if (base64_decode(password, strlen(password), NULL, buf) <= 0) {
        i_error("sha1_verify(%s): failed decoding SHA base64", user);
        return 0;
    }

    data = buffer_get_data(buf, &size);
    if (size < SHA1_RESULTLEN) {
        i_error("sha1_verify(%s): invalid SHA base64 decode", user);
        return 0;
    }

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

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

    random_fill(salt, 4);

    sha1_init(&ctx);
    sha1_loop(&ctx, plaintext, strlen(plaintext));
    sha1_loop(&ctx, salt, 4);
    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 int 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;
    struct sha1_ctxt ctx;

    /* format: base64-encoded MD5 hash and salt */
    buf = buffer_create_static(pool_datastack_create(),
                   MAX_BASE64_DECODED_SIZE(strlen(password)+1));

    if (base64_decode(password, strlen(password), 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__)
{
    unsigned char smd5_digest[20];
    unsigned char *salt = &smd5_digest[16];
    struct md5_context ctx;
    string_t *str;

    random_fill(salt, 4);

    md5_init(&ctx);
    md5_update(&ctx, plaintext, strlen(plaintext));
    md5_update(&ctx, salt, 4);
    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 int smd5_verify(const char *plaintext, const char *password,
               const char *user __attr_unused__)
{
    unsigned char md5_digest[16];
    buffer_t *buf;
    const char *data;
    size_t size;
    struct md5_context ctx;

    /* format: base64-encoded MD5 hash and salt */
    buf = buffer_create_static(pool_datastack_create(),
                   MAX_BASE64_DECODED_SIZE(strlen(password)+1));

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

    data = buffer_get_data(buf, &size);
    if (size <= 16) {
        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[16], size-16);
    md5_final(&ctx, md5_digest);
    return memcmp(md5_digest, data, 16) == 0;
}

static int 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 int hmac_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 *hmac_md5_generate(const char *plaintext,
                     const char *user __attr_unused__)
{
    return password_generate_cram_md5(plaintext);
}

static int digest_md5_verify(const char *plaintext, const char *password,
                 const char *user)
{
    unsigned char digest[16];
    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[16];

    /* 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 int plain_md5_verify(const char *plaintext, const char *password,
                const char *user __attr_unused__)
{
    unsigned char digest[16];
    const char *str;

    md5_get_digest(plaintext, strlen(plaintext), digest);
    str = binary_to_hex(digest, sizeof(digest));
    return strcasecmp(str, password) == 0;
}

static const char *plain_md5_generate(const char *plaintext,
                      const char *user __attr_unused__)
{
    unsigned char digest[16];

    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[16];
    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 int ldap_md5_verify(const char *plaintext, const char *password,
               const char *user __attr_unused__)
{
    unsigned char md5_digest[16];
    buffer_t *buf;
    const char *data;
    size_t size;

    md5_get_digest(plaintext, strlen(plaintext), md5_digest);

    buf = buffer_create_static(pool_datastack_create(),
                   MAX_BASE64_DECODED_SIZE(strlen(password)+1));

    if (base64_decode(password, strlen(password), NULL, buf) <= 0) {
        i_error("ldap_md5_verify(%s): failed decoding MD5 base64",
            user);
        return 0;
    }

    data = buffer_get_data(buf, &size);
    if (size != 16) {
        i_error("ldap_md5_verify(%s): invalid MD5 base64 decode", user);
        return 0;
    }

    return memcmp(md5_digest, data, 16) == 0;
}

static int 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 int 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 const struct password_scheme default_schemes[] = {
    { "CRYPT", crypt_verify, crypt_generate },
    { "MD5", md5_verify, md5_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 },
    { "HMAC-MD5", hmac_md5_verify, hmac_md5_generate },
    { "DIGEST-MD5", digest_md5_verify, digest_md5_generate },
    { "PLAIN-MD5", plain_md5_verify, plain_md5_generate },
    { "LDAP-MD5", ldap_md5_verify, ldap_md5_generate },
    { "LANMAN", lm_verify, lm_generate },
    { "NTLM", ntlm_verify, ntlm_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, (size_t)-1);
    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", FALSE);
    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;
}