//

// TLS routines for CUPS.

//

// Copyright © 2021-2024 by OpenPrinting.

// Copyright @ 2007-2014 by Apple Inc.

// Copyright @ 1997-2007 by Easy Software Products, all rights reserved.

//

// Licensed under Apache License v2.0.  See the file "LICENSE" for more

// information.

//

#include "cups-private.h"

#include "dir.h"

#include <fcntl.h>

#include <math.h>

#include <sys/stat.h>

#ifdef __APPLE__

#  include <Security/Security.h>

#endif // __APPLE__

#ifdef _WIN32

#  pragma comment(lib, "crypt32.lib") // Link in crypt32 library...

#  include <tchar.h>

#  include <wincrypt.h>

#else

#  include <poll.h>

#  include <signal.h>

#  include <sys/time.h>

#  include <sys/resource.h>

#endif // _WIN32

//

// Local globals...

//

static bool   tls_auto_create = false;

          // Auto-create self-signed certs?

static char   *tls_common_name = NULL;

          // Default common name

static char   *tls_keypath = NULL;

          // Certificate store path

static cups_mutex_t tls_mutex = CUPS_MUTEX_INITIALIZER;

          // Mutex for certificates

static int    tls_options = -1,// Options for TLS connections

      tls_min_version = _HTTP_TLS_1_2,

      tls_max_version = _HTTP_TLS_MAX;

#ifndef __APPLE__

static cups_array_t *tls_root_certs = NULL;

          // List of known root CAs

#endif // __APPLE__

//

// Local functions...

//

static bool   http_check_roots(const char *creds);

static char   *http_copy_file(const char *path, const char *common_name, const char *ext);

static const char *http_default_path(char *buffer, size_t bufsize);

static bool   http_default_san_cb(const char *common_name, const char *subject_alt_name, void *data);

#if defined(_WIN32) || defined(HAVE_GNUTLS)

static char   *http_der_to_pem(const unsigned char *der, size_t dersize);

#endif // _WIN32 || HAVE_GNUTLS

static const char *http_make_path(char *buffer, size_t bufsize, const char *dirname, const char *filename, const char *ext);

static bool   http_save_file(const char *path, const char *common_name, const char *ext, const char *value);

//

// Include platform-specific TLS code...

//

#ifdef HAVE_OPENSSL

#  include "tls-openssl.c"

#else // HAVE_GNUTLS

#  include "tls-gnutls.c"

#endif // HAVE_OPENSSL

//

// 'cupsCopyCredentials()' - Copy the X.509 certificate chain to a string.

//

char *

cupsCopyCredentials(

    const char *path,     // I - Directory path for certificate/key store or `NULL` for default

    const char *common_name)    // I - Common name

{

  return (http_copy_file(path, common_name, "crt"));

}

//

// 'cupsCopyCredentialsKey()' - Copy the private key to a string.

//

char *

cupsCopyCredentialsKey(

    const char *path,     // I - Directory path for certificate/key store or `NULL` for default

    const char *common_name)    // I - Common name

{

  return (http_copy_file(path, common_name, "key"));

}

//

// 'cupsCopyCredentialsPublicKey()' - Copy the public key for a X.509 certificate request.

//

char *          // O - PEM-encoded public key

cupsCopyCredentialsPublicKey(

    const char *path,     // I - Directory path for certificate/key store or `NULL` for default

    const char *common_name)    // I - Common name

{

  return (http_copy_file(path, common_name, "pub"));

}

//

// 'cupsCopyCredentialsRequest()' - Copy the X.509 certificate signing request to a string.

//

char *          // O - PEM-encoded X.509 certificate signing request

cupsCopyCredentialsRequest(

    const char *path,     // I - Directory path for certificate/key store or `NULL` for default

    const char *common_name)    // I - Common name

{

  return (http_copy_file(path, common_name, "csr"));

}

//

// 'cupsSaveCredentials()' - Save the credentials associated with a printer/server.

//

// This function saves the the PEM-encoded X.509 certificate chain string and

// private key (if not `NULL`) to the directory "path" or, if "path" is `NULL`,

// in a per-user or system-wide (when running as root) certificate/key store.

//

bool          // O - `true` on success, `false` on failure

cupsSaveCredentials(

    const char *path,     // I - Directory path for certificate/key store or `NULL` for default

    const char *common_name,    // I - Common name for certificate

    const char *credentials,    // I - PEM-encoded certificate chain or `NULL` to remove

    const char *key)      // I - PEM-encoded private key or `NULL` for none

{

  bool  ret = false;      // Return value

  char  crtfile[1024],      // Certificate filename

  keyfile[1024],      // Key filename

  ktmfile[1024];      // Temporary key filename

  // Validate input...

  if (credentials)

  {

    // Make sure it looks like a PEM-encoded cert...

    if (strncmp(credentials, "-----BEGIN CERTIFICATE-----", 27) || strstr(credentials, "-----END CERTIFICATE-----") == NULL)

      return (false);

  }

  if (key)

  {

    // Make sure it looks like a PEM-encoded private key...

    if (strncmp(key, "-----BEGIN PRIVATE KEY-----", 27) || strstr(key, "-----END PRIVATE KEY-----") == NULL)

      return (false);

  }

  // Save or delete credentials...

  http_make_path(crtfile, sizeof(crtfile), path, common_name, "crt");

  http_make_path(keyfile, sizeof(keyfile), path, common_name, "key");

  http_make_path(ktmfile, sizeof(ktmfile), path, common_name, "ktm");

  if (!credentials && !key)

  {

    // Delete credentials...

    if (!unlink(crtfile) && !unlink(keyfile))

      ret = true;

    else

      _cupsSetError(IPP_STATUS_ERROR_INTERNAL, strerror(errno), false);

  }

  else if (!credentials && key)

  {

    // Bad arguments...

    _cupsSetError(IPP_STATUS_ERROR_INTERNAL, strerror(EINVAL), false);

  }

  else if (!key && access(keyfile, 0) && access(ktmfile, 0))

  {

    // Missing key file...

    _cupsSetError(IPP_STATUS_ERROR_INTERNAL, strerror(errno), false);

  }

  else if (http_save_file(path, common_name, "crt", credentials))

  {

    // Certificate saved, save or rename key file as needed...

    if (key)

      ret = http_save_file(path, common_name, "key", key);

    else if (!access(ktmfile, 0))

      ret = !rename(ktmfile, keyfile);

    else

      ret = true;

  }

  return (ret);

}

//

// 'cupsSetServerCredentials()' - Set the default server credentials.

//

// Note: The server credentials are used by all threads in the running process.

// This function is threadsafe.

//

bool          // O - `true` on success, `false` on failure

cupsSetServerCredentials(

    const char *path,     // I - Directory path for certificate/key store or `NULL` for default

    const char *common_name,    // I - Default common name for server

    bool       auto_create)   // I - `true` = automatically create self-signed certificates

{

  char  temp[1024];     // Default path buffer

  DEBUG_printf("cupsSetServerCredentials(path=\"%s\", common_name=\"%s\", auto_create=%d)", path, common_name, auto_create);

  // Use defaults as needed...

  if (!path)

    path = http_default_path(temp, sizeof(temp));

  // Range check input...

  if (!path || !common_name)

  {

    _cupsSetError(IPP_STATUS_ERROR_INTERNAL, strerror(EINVAL), 0);

    return (0);

  }

  cupsMutexLock(&tls_mutex);

  // Free old values...

  if (tls_keypath)

    _cupsStrFree(tls_keypath);

  if (tls_common_name)

    _cupsStrFree(tls_common_name);

  // Save the new values...

  tls_keypath     = _cupsStrAlloc(path);

  tls_auto_create = auto_create;

  tls_common_name = _cupsStrAlloc(common_name);

  cupsMutexUnlock(&tls_mutex);

  return (1);

}

//

// '_httpTLSSetOptions()' - Set TLS protocol and cipher suite options.

//

void

_httpTLSSetOptions(int options,   // I - Options

                   int min_version, // I - Minimum TLS version

                   int max_version) // I - Maximum TLS version

{

  if (!(options & _HTTP_TLS_SET_DEFAULT) || tls_options < 0)

  {

    tls_options     = options;

    tls_min_version = min_version;

    tls_max_version = max_version;

  }

}

//

// 'http_check_roots()' - Check whether the supplied credentials use a trusted root CA.

//

static bool       // O - `true` if they use a trusted root, `false` otherwise

http_check_roots(const char *creds) // I - Credentials

{

  bool    ret = false;    // Return value

#ifdef __APPLE__

  // Apple hides all of the keychain stuff (all deprecated) so the best we can

  // do is use the SecTrust API to evaluate the certificate...

  CFMutableArrayRef certs = NULL; // Certificates from credentials

  SecCertificateRef cert;

  char      *tcreds = NULL, // Copy of credentials string

      *tstart,  // Start of certificate data

      *tend,    // End of certificate data

      *der = NULL;  // DER-encoded fragment buffer

  size_t    dersize,  // Size of DER buffer

      derlen;   // Length of DER data

  SecPolicyRef    policy;   // X.509 policy

  SecTrustRef   trust;    // Trust evaluator

  // Convert PEM-encoded credentials to an array of DER-encoded certificates...

  if ((tcreds = strdup(creds)) == NULL)

    goto done;

  if ((certs = CFArrayCreateMutable(kCFAllocatorDefault, /*capacity*/0, &kCFTypeArrayCallBacks)) == NULL)

    goto done;

  dersize = 3 * strlen(tcreds) / 4;

  if ((der = malloc(dersize)) == NULL)

    goto done;

  for (tstart = strstr(tcreds, "-----BEGIN CERTIFICATE-----\n"); tstart; tstart = strstr(tend, "-----BEGIN CERTIFICATE-----\n"))

  {

    // Find the end of the certificate data...

    tstart += 28;     // Skip "-----BEGIN CERTIFICATE-----\n"

    if ((tend = strstr(tstart, "-----END CERTIFICATE-----\n")) == NULL)

      break;        // Missing end...

    // Nul-terminate the cert data...

    *tend++ = '\0';

    // Convert to DER format

    derlen = dersize;

    if (httpDecode64(der, &derlen, tstart, /*end*/NULL))

    {

      // Create a CFData object for the data...

      CFDataRef data = CFDataCreate(kCFAllocatorDefault, (const UInt8 *)der, (CFIndex)derlen);

      if (data)

      {

        // Create a certificate from the DER data...

        if ((cert = SecCertificateCreateWithData(kCFAllocatorDefault, data)) != NULL)

        {

          // Add certificate to the array...

          CFArrayAppendValue(certs, cert);

          CFRelease(cert);

  }

        CFRelease(data);

      }

    }

  }

  // Test the certificate list against the macOS/iOS trust store...

  if ((policy = SecPolicyCreateBasicX509()) != NULL)

  {

    if (SecTrustCreateWithCertificates(certs, policy, &trust) == noErr)

    {

      ret = SecTrustEvaluateWithError(trust, NULL);

      CFRelease(trust);

    }

    CFRelease(policy);

  }

  done:

  free(tcreds);

  free(der);

  if (certs)

    CFRelease(certs);

#else

  size_t  credslen;   // Length of credentials string

  const char  *rcreds;    // Current root credential

  size_t  rcredslen;    // Length of current root credential

  cupsMutexLock(&tls_mutex);

  // Load root certificates as needed...

  if (!tls_root_certs)

  {

    // Load root certificates...

    tls_root_certs = cupsArrayNew(/*cb*/NULL, /*cb_data*/NULL, /*hash_cb*/NULL, /*hash_size*/0, /*copy_cb*/NULL, /*free_cb*/NULL);

#  ifdef _WIN32

    int     i;    // Looping var

    HCERTSTORE    store;    // Certificate store

    CERT_CONTEXT  *cert;    // Current certificate

    // Add certificates in both the "ROOT" and "CA" stores...

    for (i = 0; i < 2; i ++)

    {

      if ((store = CertOpenStore(CERT_STORE_PROV_SYSTEM, 0, 0, CERT_SYSTEM_STORE_CURRENT_USER, i ? L"CA" : L"ROOT")) == NULL)

        continue;

      // Loop through certificates...

      for (cert = CertEnumCertificatesInStore(store, NULL); cert; cert = CertEnumCertificatesInStore(store, cert))

      {

        if (cert->dwCertEncodingType == X509_ASN_ENCODING)

        {

          // Convert DER to PEM and add to the list...

          char * pem = http_der_to_pem(cert->pbCertEncoded, cert->cbCertEncoded);

          if (pem)

            cupsArrayAdd(tls_root_certs, pem);

  }

      }

      CertCloseStore(store, 0);

    }

#  else

    size_t    i;    // Looping var

    cups_dir_t    *dir;   // Directory

    cups_dentry_t *dent;    // Directory entry

    const char    *ext;   // Pointer to filename extension

    static const char * const root_dirs[] =

    {         // Root certificate stores

      "/etc/ssl/certs",

      "/system/etc/security/cacerts/",

    };

    for (i = 0, dir = NULL; i < (sizeof(root_dirs) / sizeof(root_dirs[0])); i ++)

    {

      if ((dir = cupsDirOpen(root_dirs[i])) != NULL)

        break;

    }

    if (dir)

    {

      while ((dent = cupsDirRead(dir)) != NULL)

      {

        if ((ext = strrchr(dent->filename, '.')) != NULL && !strcmp(ext, ".pem"))

        {

          char  filename[1024],   // Certificate filename

    *cert;      // Certificate data

    int fd;     // File descriptor

    snprintf(filename, sizeof(filename), "%s/%s", root_dirs[i], dent->filename);

          if ((fd = open(filename, O_RDONLY)) >= 0)

          {

            if ((cert = calloc(1, (size_t)(dent->fileinfo.st_size + 1))) != NULL)

      {

        read(fd, cert, (size_t)dent->fileinfo.st_size);

        cupsArrayAdd(tls_root_certs, cert);

      }

      close(fd);

    }

  }

      }

    }

#  endif // _WIN32

  }

  // Check all roots

  credslen = strlen(creds);

  DEBUG_printf("4http_check_roots: %lu root certificates to check.", (unsigned long)cupsArrayGetCount(tls_root_certs));

  for (rcreds = (const char *)cupsArrayGetFirst(tls_root_certs); rcreds && !ret; rcreds = (const char *)cupsArrayGetNext(tls_root_certs))

  {

    // Compare the root against the tail of the current credentials...

    rcredslen = strlen(rcreds);

    if (credslen >= rcredslen && !strcmp(creds + (credslen - rcredslen), rcreds))

      ret = true;

  }

  // Unlock access and return...

  cupsMutexUnlock(&tls_mutex);

#endif // __APPLE__

  return (ret);

}

//

// 'http_copy_file()' - Copy the contents of a file to a string.

//

static char *       // O - Contents of file or `NULL` on error

http_copy_file(const char *path,  // I - Directory

               const char *common_name, // I - Common name

               const char *ext)   // I - Extension

{

  char    *s = NULL;    // String

  int   fd;     // File descriptor

  char    defpath[1024],    // Default path

    filename[1024];   // Filename

  struct stat fileinfo;   // File information

  if (!common_name)

    return (NULL);

  if (!path)

    path = http_default_path(defpath, sizeof(defpath));

  if ((fd = open(http_make_path(filename, sizeof(filename), path, common_name, ext), O_RDONLY)) < 0)

    return (NULL);

  if (fstat(fd, &fileinfo))

    goto done;

  if (fileinfo.st_size > 65536)

  {

    close(fd);

    return (NULL);

  }

  if ((s = calloc(1, (size_t)fileinfo.st_size + 1)) == NULL)

  {

    close(fd);

    return (NULL);

  }

  if (read(fd, s, (size_t)fileinfo.st_size) < 0)

  {

    free(s);

    s = NULL;

  }

  done:

  close(fd);

  return (s);

}

//

// 'http_default_path()' - Get the default credential store path.

//

static const char *     // O - Path or NULL on error

http_default_path(

    char   *buffer,     // I - Path buffer

    size_t bufsize)     // I - Size of path buffer

{

  _cups_globals_t *cg = _cupsGlobals();

          // Pointer to library globals

  if (cg->userconfig)

  {

    snprintf(buffer, bufsize, "%s/ssl", cg->userconfig);

    if (!_cupsDirCreate(buffer, 0700))

    {

      DEBUG_printf("1http_default_path: Failed to make directory '%s': %s", buffer, strerror(errno));

      return (NULL);

    }

  }

  else

  {

    snprintf(buffer, bufsize, "%s/ssl", cg->sysconfig);

    if (!_cupsDirCreate(buffer, 0700))

    {

      DEBUG_printf("1http_default_path: Failed to make directory '%s': %s", buffer, strerror(errno));

      return (NULL);

    }

  }

  DEBUG_printf("1http_default_path: Using default path \"%s\".", buffer);

  return (buffer);

}

//

// 'http_default_san_cb()' - Validate a subjectAltName value.

//

static bool       // O - `true` if OK, `false` otherwise

http_default_san_cb(

    const char *common_name,    // I - Common name value

    const char *subject_alt_name, // I - subjectAltName value

    void       *data)     // I - Callback data (unused)

{

  size_t  common_len;   // Common name length

  (void)data;

  if (!_cups_strcasecmp(subject_alt_name, common_name) || !_cups_strcasecmp(subject_alt_name, "localhost"))

    return (true);

  common_len = strlen(common_name);

  return (!_cups_strncasecmp(subject_alt_name, common_name, common_len) && subject_alt_name[common_len] == '.');

}

#if defined(_WIN32) || defined(HAVE_GNUTLS)

//

// 'http_der_to_pem()' - Convert DER format certificate data to PEM.

//

static char *       // O - PEM string

http_der_to_pem(

     const unsigned char *der,    // I - DER-encoded data

     size_t              dersize) // I - Size of DER-encoded data

{

  char    *pem,     // PEM-encoded string

    *pemptr;    // Pointer into PEM-encoded string

  int   col;      // Current column

  size_t  pemsize;    // Size of PEM-encoded string

  static const char *base64 =   // Base64 alphabet

    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

  // Calculate the size, accounting for Base64 expansion, line wrapping at

  // column 64, and the BEGIN/END CERTIFICATE text...

  pemsize = 2 * dersize + /*"-----BEGIN CERTIFICATE-----\n"*/28 + /*"-----END CERTIFICATE-----\n"*/26 + 1;

  if ((pem = calloc(1, pemsize)) == NULL)

    return (NULL);

  cupsCopyString(pem, "-----BEGIN CERTIFICATE-----\n", pemsize);

  for (pemptr = pem + strlen(pem), col = 0; dersize > 0; der += 3)

  {

    // Encode the up to 3 characters as 4 Base64 numbers...

    switch (dersize)

    {

      case 1 :

          *pemptr ++ = base64[(der[0] & 255) >> 2];

    *pemptr ++ = base64[((der[0] & 255) << 4) & 63];

    *pemptr ++ = '=';

    *pemptr ++ = '=';

    dersize = 0;

          break;

      case 2 :

          *pemptr ++ = base64[(der[0] & 255) >> 2];

    *pemptr ++ = base64[(((der[0] & 255) << 4) | ((der[1] & 255) >> 4)) & 63];

    *pemptr ++ = base64[((der[1] & 255) << 2) & 63];

    *pemptr ++ = '=';

    dersize = 0;

          break;

      default :

          *pemptr ++ = base64[(der[0] & 255) >> 2];

    *pemptr ++ = base64[(((der[0] & 255) << 4) | ((der[1] & 255) >> 4)) & 63];

    *pemptr ++ = base64[(((der[1] & 255) << 2) | ((der[2] & 255) >> 6)) & 63];

    *pemptr ++ = base64[der[2] & 63];

    dersize -= 3;

          break;

    }

    // Add a newline as needed...

    col += 4;

    if (col >= 64)

    {

      *pemptr++ = '\n';

      col = 0;

    }

  }

  if (col > 0)

    *pemptr++ = '\n';

  *pemptr = '\0';

  cupsConcatString(pem, "-----END CERTIFICATE-----\n", pemsize);

  // Return the encoded string...

  return (pem);

}

#endif // _WIN32 || HAVE_GNUTLS

//

// 'http_make_path()' - Format a filename for a certificate or key file.

//

static const char *     // O - Filename

http_make_path(

    char       *buffer,     // I - Filename buffer

    size_t     bufsize,     // I - Size of buffer

    const char *dirname,    // I - Directory

    const char *filename,   // I - Filename (usually hostname)

    const char *ext)      // I - Extension

{

  char  *bufptr,      // Pointer into buffer

  *bufend = buffer + bufsize - 1; // End of buffer

  snprintf(buffer, bufsize, "%s/", dirname);

  bufptr = buffer + strlen(buffer);

  while (*filename && bufptr < bufend)

  {

    if (_cups_isalnum(*filename) || *filename == '-' || *filename == '.')

      *bufptr++ = *filename;

    else

      *bufptr++ = '_';

    filename ++;

  }

  if (bufptr < bufend && filename[-1] != '.')

    *bufptr++ = '.';

  cupsCopyString(bufptr, ext, (size_t)(bufend - bufptr + 1));

  return (buffer);

}

//

// 'http_save_file()' - Save a string to a file.

//

static bool       // O - `true` on success, `false` on failure

http_save_file(const char *path,  // I - Directory path for certificate/key store or `NULL` for default

               const char *common_name, // I - Common name

               const char *ext,   // I - Extension

         const char *value) // I - String value

{

  char  defpath[1024],      // Default path

  filename[1024];     // Output filename

  int fd;       // File descriptor

  // Range check input...

  if (!common_name)

    return (false);

  // Get default path as needed...

  if (!path)

    path = http_default_path(defpath, sizeof(defpath));

  http_make_path(filename, sizeof(filename), path, common_name, ext);

  if (!value)

  {

    unlink(filename);

    return (true);

  }

  if ((fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, 0644)) < 0)

    return (false);

  if (write(fd, value, strlen(value)) < 0)

  {

    close(fd);

    unlink(filename);

    return (false);

  }

  close(fd);

  return (true);

}