krb5: merged security.c and krb specific FTP functions in here

These two files were always tightly connected and it was hard to
understand what went into which. This also allows us to make the
ftpsend() function static (moved from ftp.c).

Removed security.c
Renamed curl_sec.h to krb5.h

Closes #5987

1 files changed, 582 insertions, 14 deletions

diff --git a/lib/krb5.c b/lib/krb5.c
index f50287aec..b300a8cdf 100644
--- a/lib/krb5.c
+++ b/lib/krb5.c
@@ -2,7 +2,7 @@
  *
  * Copyright (c) 1995, 1996, 1997, 1998, 1999 Kungliga Tekniska Högskolan
  * (Royal Institute of Technology, Stockholm, Sweden).
- * Copyright (c) 2004 - 2019 Daniel Stenberg
+ * Copyright (c) 2004 - 2020 Daniel Stenberg
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -45,14 +45,74 @@
 #include "ftp.h"
 #include "curl_gssapi.h"
 #include "sendf.h"
-#include "curl_sec.h"
+#include "krb5.h"
 #include "warnless.h"
+#include "non-ascii.h"
+#include "strcase.h"
+#include "strdup.h"
 
 /* The last 3 #include files should be in this order */
 #include "curl_printf.h"
 #include "curl_memory.h"
 #include "memdebug.h"
 
+static CURLcode ftpsend(struct connectdata *conn, const char *cmd)
+{
+  ssize_t bytes_written;
+#define SBUF_SIZE 1024
+  char s[SBUF_SIZE];
+  size_t write_len;
+  char *sptr = s;
+  CURLcode result = CURLE_OK;
+#ifdef HAVE_GSSAPI
+  enum protection_level data_sec = conn->data_prot;
+#endif
+
+  if(!cmd)
+    return CURLE_BAD_FUNCTION_ARGUMENT;
+
+  write_len = strlen(cmd);
+  if(!write_len || write_len > (sizeof(s) -3))
+    return CURLE_BAD_FUNCTION_ARGUMENT;
+
+  memcpy(&s, cmd, write_len);
+  strcpy(&s[write_len], "\r\n"); /* append a trailing CRLF */
+  write_len += 2;
+  bytes_written = 0;
+
+  result = Curl_convert_to_network(conn->data, s, write_len);
+  /* Curl_convert_to_network calls failf if unsuccessful */
+  if(result)
+    return result;
+
+  for(;;) {
+#ifdef HAVE_GSSAPI
+    conn->data_prot = PROT_CMD;
+#endif
+    result = Curl_write(conn, conn->sock[FIRSTSOCKET], sptr, write_len,
+                        &bytes_written);
+#ifdef HAVE_GSSAPI
+    DEBUGASSERT(data_sec > PROT_NONE && data_sec < PROT_LAST);
+    conn->data_prot = data_sec;
+#endif
+
+    if(result)
+      break;
+
+    if(conn->data->set.verbose)
+      Curl_debug(conn->data, CURLINFO_HEADER_OUT, sptr, (size_t)bytes_written);
+
+    if(bytes_written != (ssize_t)write_len) {
+      write_len -= bytes_written;
+      sptr += bytes_written;
+    }
+    else
+      break;
+  }
+
+  return result;
+}
+
 static int
 krb5_init(void *app_data)
 {
@@ -183,7 +243,7 @@ krb5_auth(void *app_data, struct connectdata *conn)
   for(;;) {
     /* this really shouldn't be repeated here, but can't help it */
     if(service == srv_host) {
-      result = Curl_ftpsend(conn, "AUTH GSSAPI");
+      result = ftpsend(conn, "AUTH GSSAPI");
       if(result)
         return -2;
 
@@ -260,7 +320,7 @@ krb5_auth(void *app_data, struct connectdata *conn)
 
         cmd = aprintf("ADAT %s", p);
         if(cmd)
-          result = Curl_ftpsend(conn, cmd);
+          result = ftpsend(conn, cmd);
         else
           result = CURLE_OUT_OF_MEMORY;
 
@@ -326,16 +386,524 @@ static void krb5_end(void *app_data)
     }
 }
 
-struct Curl_sec_client_mech Curl_krb5_client_mech = {
-    "GSSAPI",
-    sizeof(gss_ctx_id_t),
-    krb5_init,
-    krb5_auth,
-    krb5_end,
-    krb5_check_prot,
-    krb5_overhead,
-    krb5_encode,
-    krb5_decode
+static struct Curl_sec_client_mech Curl_krb5_client_mech = {
+  "GSSAPI",
+  sizeof(gss_ctx_id_t),
+  krb5_init,
+  krb5_auth,
+  krb5_end,
+  krb5_check_prot,
+  krb5_overhead,
+  krb5_encode,
+  krb5_decode
+};
+
+static const struct {
+  enum protection_level level;
+  const char *name;
+} level_names[] = {
+  { PROT_CLEAR, "clear" },
+  { PROT_SAFE, "safe" },
+  { PROT_CONFIDENTIAL, "confidential" },
+  { PROT_PRIVATE, "private" }
 };
 
+static enum protection_level
+name_to_level(const char *name)
+{
+  int i;
+  for(i = 0; i < (int)sizeof(level_names)/(int)sizeof(level_names[0]); i++)
+    if(checkprefix(name, level_names[i].name))
+      return level_names[i].level;
+  return PROT_NONE;
+}
+
+/* Convert a protocol |level| to its char representation.
+   We take an int to catch programming mistakes. */
+static char level_to_char(int level)
+{
+  switch(level) {
+  case PROT_CLEAR:
+    return 'C';
+  case PROT_SAFE:
+    return 'S';
+  case PROT_CONFIDENTIAL:
+    return 'E';
+  case PROT_PRIVATE:
+    return 'P';
+  case PROT_CMD:
+    /* Fall through */
+  default:
+    /* Those 2 cases should not be reached! */
+    break;
+  }
+  DEBUGASSERT(0);
+  /* Default to the most secure alternative. */
+  return 'P';
+}
+
+/* Send an FTP command defined by |message| and the optional arguments. The
+   function returns the ftp_code. If an error occurs, -1 is returned. */
+static int ftp_send_command(struct connectdata *conn, const char *message, ...)
+{
+  int ftp_code;
+  ssize_t nread = 0;
+  va_list args;
+  char print_buffer[50];
+
+  va_start(args, message);
+  mvsnprintf(print_buffer, sizeof(print_buffer), message, args);
+  va_end(args);
+
+  if(ftpsend(conn, print_buffer)) {
+    ftp_code = -1;
+  }
+  else {
+    if(Curl_GetFTPResponse(&nread, conn, &ftp_code))
+      ftp_code = -1;
+  }
+
+  (void)nread; /* Unused */
+  return ftp_code;
+}
+
+/* Read |len| from the socket |fd| and store it in |to|. Return a CURLcode
+   saying whether an error occurred or CURLE_OK if |len| was read. */
+static CURLcode
+socket_read(curl_socket_t fd, void *to, size_t len)
+{
+  char *to_p = to;
+  CURLcode result;
+  ssize_t nread = 0;
+
+  while(len > 0) {
+    result = Curl_read_plain(fd, to_p, len, &nread);
+    if(!result) {
+      len -= nread;
+      to_p += nread;
+    }
+    else {
+      if(result == CURLE_AGAIN)
+        continue;
+      return result;
+    }
+  }
+  return CURLE_OK;
+}
+
+
+/* Write |len| bytes from the buffer |to| to the socket |fd|. Return a
+   CURLcode saying whether an error occurred or CURLE_OK if |len| was
+   written. */
+static CURLcode
+socket_write(struct connectdata *conn, curl_socket_t fd, const void *to,
+             size_t len)
+{
+  const char *to_p = to;
+  CURLcode result;
+  ssize_t written;
+
+  while(len > 0) {
+    result = Curl_write_plain(conn, fd, to_p, len, &written);
+    if(!result) {
+      len -= written;
+      to_p += written;
+    }
+    else {
+      if(result == CURLE_AGAIN)
+        continue;
+      return result;
+    }
+  }
+  return CURLE_OK;
+}
+
+static CURLcode read_data(struct connectdata *conn,
+                          curl_socket_t fd,
+                          struct krb5buffer *buf)
+{
+  int len;
+  CURLcode result;
+
+  result = socket_read(fd, &len, sizeof(len));
+  if(result)
+    return result;
+
+  if(len) {
+    /* only realloc if there was a length */
+    len = ntohl(len);
+    buf->data = Curl_saferealloc(buf->data, len);
+  }
+  if(!len || !buf->data)
+    return CURLE_OUT_OF_MEMORY;
+
+  result = socket_read(fd, buf->data, len);
+  if(result)
+    return result;
+  buf->size = conn->mech->decode(conn->app_data, buf->data, len,
+                                 conn->data_prot, conn);
+  buf->index = 0;
+  return CURLE_OK;
+}
+
+static size_t
+buffer_read(struct krb5buffer *buf, void *data, size_t len)
+{
+  if(buf->size - buf->index < len)
+    len = buf->size - buf->index;
+  memcpy(data, (char *)buf->data + buf->index, len);
+  buf->index += len;
+  return len;
+}
+
+/* Matches Curl_recv signature */
+static ssize_t sec_recv(struct connectdata *conn, int sockindex,
+                        char *buffer, size_t len, CURLcode *err)
+{
+  size_t bytes_read;
+  size_t total_read = 0;
+  curl_socket_t fd = conn->sock[sockindex];
+
+  *err = CURLE_OK;
+
+  /* Handle clear text response. */
+  if(conn->sec_complete == 0 || conn->data_prot == PROT_CLEAR)
+      return sread(fd, buffer, len);
+
+  if(conn->in_buffer.eof_flag) {
+    conn->in_buffer.eof_flag = 0;
+    return 0;
+  }
+
+  bytes_read = buffer_read(&conn->in_buffer, buffer, len);
+  len -= bytes_read;
+  total_read += bytes_read;
+  buffer += bytes_read;
+
+  while(len > 0) {
+    if(read_data(conn, fd, &conn->in_buffer))
+      return -1;
+    if(conn->in_buffer.size == 0) {
+      if(bytes_read > 0)
+        conn->in_buffer.eof_flag = 1;
+      return bytes_read;
+    }
+    bytes_read = buffer_read(&conn->in_buffer, buffer, len);
+    len -= bytes_read;
+    total_read += bytes_read;
+    buffer += bytes_read;
+  }
+  return total_read;
+}
+
+/* Send |length| bytes from |from| to the |fd| socket taking care of encoding
+   and negotiating with the server. |from| can be NULL. */
+static void do_sec_send(struct connectdata *conn, curl_socket_t fd,
+                        const char *from, int length)
+{
+  int bytes, htonl_bytes; /* 32-bit integers for htonl */
+  char *buffer = NULL;
+  char *cmd_buffer;
+  size_t cmd_size = 0;
+  CURLcode error;
+  enum protection_level prot_level = conn->data_prot;
+  bool iscmd = (prot_level == PROT_CMD)?TRUE:FALSE;
+
+  DEBUGASSERT(prot_level > PROT_NONE && prot_level < PROT_LAST);
+
+  if(iscmd) {
+    if(!strncmp(from, "PASS ", 5) || !strncmp(from, "ACCT ", 5))
+      prot_level = PROT_PRIVATE;
+    else
+      prot_level = conn->command_prot;
+  }
+  bytes = conn->mech->encode(conn->app_data, from, length, prot_level,
+                             (void **)&buffer);
+  if(!buffer || bytes <= 0)
+    return; /* error */
+
+  if(iscmd) {
+    error = Curl_base64_encode(conn->data, buffer, curlx_sitouz(bytes),
+                               &cmd_buffer, &cmd_size);
+    if(error) {
+      free(buffer);
+      return; /* error */
+    }
+    if(cmd_size > 0) {
+      static const char *enc = "ENC ";
+      static const char *mic = "MIC ";
+      if(prot_level == PROT_PRIVATE)
+        socket_write(conn, fd, enc, 4);
+      else
+        socket_write(conn, fd, mic, 4);
+
+      socket_write(conn, fd, cmd_buffer, cmd_size);
+      socket_write(conn, fd, "\r\n", 2);
+      infof(conn->data, "Send: %s%s\n", prot_level == PROT_PRIVATE?enc:mic,
+            cmd_buffer);
+      free(cmd_buffer);
+    }
+  }
+  else {
+    htonl_bytes = htonl(bytes);
+    socket_write(conn, fd, &htonl_bytes, sizeof(htonl_bytes));
+    socket_write(conn, fd, buffer, curlx_sitouz(bytes));
+  }
+  free(buffer);
+}
+
+static ssize_t sec_write(struct connectdata *conn, curl_socket_t fd,
+                         const char *buffer, size_t length)
+{
+  ssize_t tx = 0, len = conn->buffer_size;
+
+  len -= conn->mech->overhead(conn->app_data, conn->data_prot,
+                              curlx_sztosi(len));
+  if(len <= 0)
+    len = length;
+  while(length) {
+    if(length < (size_t)len)
+      len = length;
+
+    do_sec_send(conn, fd, buffer, curlx_sztosi(len));
+    length -= len;
+    buffer += len;
+    tx += len;
+  }
+  return tx;
+}
+
+/* Matches Curl_send signature */
+static ssize_t sec_send(struct connectdata *conn, int sockindex,
+                        const void *buffer, size_t len, CURLcode *err)
+{
+  curl_socket_t fd = conn->sock[sockindex];
+  *err = CURLE_OK;
+  return sec_write(conn, fd, buffer, len);
+}
+
+int Curl_sec_read_msg(struct connectdata *conn, char *buffer,
+                      enum protection_level level)
+{
+  /* decoded_len should be size_t or ssize_t but conn->mech->decode returns an
+     int */
+  int decoded_len;
+  char *buf;
+  int ret_code = 0;
+  size_t decoded_sz = 0;
+  CURLcode error;
+
+  if(!conn->mech)
+    /* not inititalized, return error */
+    return -1;
+
+  DEBUGASSERT(level > PROT_NONE && level < PROT_LAST);
+
+  error = Curl_base64_decode(buffer + 4, (unsigned char **)&buf, &decoded_sz);
+  if(error || decoded_sz == 0)
+    return -1;
+
+  if(decoded_sz > (size_t)INT_MAX) {
+    free(buf);
+    return -1;
+  }
+  decoded_len = curlx_uztosi(decoded_sz);
+
+  decoded_len = conn->mech->decode(conn->app_data, buf, decoded_len,
+                                   level, conn);
+  if(decoded_len <= 0) {
+    free(buf);
+    return -1;
+  }
+
+  if(conn->data->set.verbose) {
+    buf[decoded_len] = '\n';
+    Curl_debug(conn->data, CURLINFO_HEADER_IN, buf, decoded_len + 1);
+  }
+
+  buf[decoded_len] = '\0';
+  if(decoded_len <= 3)
+    /* suspiciously short */
+    return 0;
+
+  if(buf[3] != '-')
+    /* safe to ignore return code */
+    (void)sscanf(buf, "%d", &ret_code);
+
+  if(buf[decoded_len - 1] == '\n')
+    buf[decoded_len - 1] = '\0';
+  strcpy(buffer, buf);
+  free(buf);
+  return ret_code;
+}
+
+static int sec_set_protection_level(struct connectdata *conn)
+{
+  int code;
+  enum protection_level level = conn->request_data_prot;
+
+  DEBUGASSERT(level > PROT_NONE && level < PROT_LAST);
+
+  if(!conn->sec_complete) {
+    infof(conn->data, "Trying to change the protection level after the"
+                      " completion of the data exchange.\n");
+    return -1;
+  }
+
+  /* Bail out if we try to set up the same level */
+  if(conn->data_prot == level)
+    return 0;
+
+  if(level) {
+    char *pbsz;
+    static unsigned int buffer_size = 1 << 20; /* 1048576 */
+
+    code = ftp_send_command(conn, "PBSZ %u", buffer_size);
+    if(code < 0)
+      return -1;
+
+    if(code/100 != 2) {
+      failf(conn->data, "Failed to set the protection's buffer size.");
+      return -1;
+    }
+    conn->buffer_size = buffer_size;
+
+    pbsz = strstr(conn->data->state.buffer, "PBSZ=");
+    if(pbsz) {
+      /* ignore return code, use default value if it fails */
+      (void)sscanf(pbsz, "PBSZ=%u", &buffer_size);
+      if(buffer_size < conn->buffer_size)
+        conn->buffer_size = buffer_size;
+    }
+  }
+
+  /* Now try to negiociate the protection level. */
+  code = ftp_send_command(conn, "PROT %c", level_to_char(level));
+
+  if(code < 0)
+    return -1;
+
+  if(code/100 != 2) {
+    failf(conn->data, "Failed to set the protection level.");
+    return -1;
+  }
+
+  conn->data_prot = level;
+  if(level == PROT_PRIVATE)
+    conn->command_prot = level;
+
+  return 0;
+}
+
+int
+Curl_sec_request_prot(struct connectdata *conn, const char *level)
+{
+  enum protection_level l = name_to_level(level);
+  if(l == PROT_NONE)
+    return -1;
+  DEBUGASSERT(l > PROT_NONE && l < PROT_LAST);
+  conn->request_data_prot = l;
+  return 0;
+}
+
+static CURLcode choose_mech(struct connectdata *conn)
+{
+  int ret;
+  struct Curl_easy *data = conn->data;
+  void *tmp_allocation;
+  const struct Curl_sec_client_mech *mech = &Curl_krb5_client_mech;
+
+  tmp_allocation = realloc(conn->app_data, mech->size);
+  if(tmp_allocation == NULL) {
+    failf(data, "Failed realloc of size %zu", mech->size);
+    mech = NULL;
+    return CURLE_OUT_OF_MEMORY;
+  }
+  conn->app_data = tmp_allocation;
+
+  if(mech->init) {
+    ret = mech->init(conn->app_data);
+    if(ret) {
+      infof(data, "Failed initialization for %s. Skipping it.\n",
+            mech->name);
+      return CURLE_FAILED_INIT;
+    }
+  }
+
+  infof(data, "Trying mechanism %s...\n", mech->name);
+  ret = ftp_send_command(conn, "AUTH %s", mech->name);
+  if(ret < 0)
+    return CURLE_COULDNT_CONNECT;
+
+  if(ret/100 != 3) {
+    switch(ret) {
+    case 504:
+      infof(data, "Mechanism %s is not supported by the server (server "
+            "returned ftp code: 504).\n", mech->name);
+      break;
+    case 534:
+      infof(data, "Mechanism %s was rejected by the server (server returned "
+            "ftp code: 534).\n", mech->name);
+      break;
+    default:
+      if(ret/100 == 5) {
+        infof(data, "server does not support the security extensions\n");
+        return CURLE_USE_SSL_FAILED;
+      }
+      break;
+    }
+    return CURLE_LOGIN_DENIED;
+  }
+
+  /* Authenticate */
+  ret = mech->auth(conn->app_data, conn);
+
+  if(ret != AUTH_CONTINUE) {
+    if(ret != AUTH_OK) {
+      /* Mechanism has dumped the error to stderr, don't error here. */
+      return CURLE_USE_SSL_FAILED;
+    }
+    DEBUGASSERT(ret == AUTH_OK);
+
+    conn->mech = mech;
+    conn->sec_complete = 1;
+    conn->recv[FIRSTSOCKET] = sec_recv;
+    conn->send[FIRSTSOCKET] = sec_send;
+    conn->recv[SECONDARYSOCKET] = sec_recv;
+    conn->send[SECONDARYSOCKET] = sec_send;
+    conn->command_prot = PROT_SAFE;
+    /* Set the requested protection level */
+    /* BLOCKING */
+    (void)sec_set_protection_level(conn);
+  }
+
+  return CURLE_OK;
+}
+
+CURLcode
+Curl_sec_login(struct connectdata *conn)
+{
+  return choose_mech(conn);
+}
+
+
+void
+Curl_sec_end(struct connectdata *conn)
+{
+  if(conn->mech != NULL && conn->mech->end)
+    conn->mech->end(conn->app_data);
+  free(conn->app_data);
+  conn->app_data = NULL;
+  if(conn->in_buffer.data) {
+    free(conn->in_buffer.data);
+    conn->in_buffer.data = NULL;
+    conn->in_buffer.size = 0;
+    conn->in_buffer.index = 0;
+    conn->in_buffer.eof_flag = 0;
+  }
+  conn->sec_complete = 0;
+  conn->data_prot = PROT_CLEAR;
+  conn->mech = NULL;
+}
+
 #endif /* HAVE_GSSAPI && !CURL_DISABLE_FTP */