src/ssl/bio.h

   1 /*
   2  * Copyright (C) 1996-2018 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 #ifndef SQUID_SSL_BIO_H
  10 #define SQUID_SSL_BIO_H
  11
  12 #if USE_OPENSSL
  13
  14 #include "compat/openssl.h"
  15 #include "FadingCounter.h"
  16 #include "fd.h"
  17 #include "MemBuf.h"
  18 #include "security/Handshake.h"
  19 #include "ssl/support.h"
  20
  21 #include <iosfwd>
  22 #include <list>
  23 #if HAVE_OPENSSL_BIO_H
  24 #include <openssl/bio.h>
  25 #endif
  26 #include <string>
  27 #include <type_traits>
  28
  29 namespace Ssl
  30 {
  31
  32 /// BIO source and sink node, handling socket I/O and monitoring SSL state
  33 class Bio
  34 {
  35 public:
  36     explicit Bio(const int anFd);
  37     virtual ~Bio();
  38
  39     /// Writes the given data to socket
  40     virtual int write(const char *buf, int size, BIO *table);
  41
  42     /// Reads data from socket
  43     virtual int read(char *buf, int size, BIO *table);
  44
  45     /// Flushes any buffered data to socket.
  46     /// The Ssl::Bio does not buffer any data, so this method has nothing to do
  47     virtual void flush(BIO *table) {}
  48
  49     int fd() const { return fd_; } ///< The SSL socket descriptor
  50
  51     /// Called by linked SSL connection whenever state changes, an alert
  52     /// appears, or an error occurs. See SSL_set_info_callback().
  53     virtual void stateChanged(const SSL *ssl, int where, int ret);
  54
  55     /// Creates a low-level BIO table, creates a high-level Ssl::Bio object
  56     /// for a given socket, and then links the two together via BIO_C_SET_FD.
  57     static BIO *Create(const int fd, Security::Io::Type type);
  58     /// Tells ssl connection to use BIO and monitor state via stateChanged()
  59     static void Link(SSL *ssl, BIO *bio);
  60
  61     const SBuf &rBufData() {return rbuf;} ///< The buffered input data
  62 protected:
  63     const int fd_; ///< the SSL socket we are reading and writing
  64     SBuf rbuf;  ///< Used to buffer input data.
  65 };
  66
  67 /// BIO node to handle socket IO for squid client side
  68 /// If bumping is enabled  this Bio detects and analyses client hello message
  69 /// to retrieve the SSL features supported by the client
  70 class ClientBio: public Bio
  71 {
  72 public:
  73     explicit ClientBio(const int anFd);
  74
  75     /// The ClientBio version of the Ssl::Bio::stateChanged method
  76     /// When the client hello message retrieved, fill the
  77     /// "features" member with the client provided informations.
  78     virtual void stateChanged(const SSL *ssl, int where, int ret);
  79     /// The ClientBio version of the Ssl::Bio::write method
  80     virtual int write(const char *buf, int size, BIO *table);
  81     /// The ClientBio version of the Ssl::Bio::read method
  82     /// If the holdRead flag is true then it does not write any data
  83     /// to socket and sets the "read retry" flag of the BIO to true
  84     virtual int read(char *buf, int size, BIO *table);
  85     /// Prevents or allow writting on socket.
  86     void hold(bool h) {holdRead_ = holdWrite_ = h;}
  87
  88     /// Sets the buffered input data (Bio::rbuf).
  89     /// Used to pass payload data (normally client HELLO data) retrieved
  90     /// by the caller.
  91     void setReadBufData(SBuf &data) {rbuf = data;}
  92 private:
  93     /// approximate size of a time window for computing client-initiated renegotiation rate (in seconds)
  94     static const time_t RenegotiationsWindow = 10;
  95
  96     /// the maximum tolerated number of client-initiated renegotiations in RenegotiationsWindow
  97     static const int RenegotiationsLimit = 5;
  98
  99     bool holdRead_; ///< The read hold state of the bio.
 100     bool holdWrite_;  ///< The write hold state of the bio.
 101     int helloSize; ///< The SSL hello message sent by client size
 102     FadingCounter renegotiations; ///< client requested renegotiations limit control
 103
 104     /// why we should terminate the connection during next TLS operation (or nil)
 105     const char *abortReason;
 106 };
 107
 108 /// BIO node to handle socket IO for squid server side
 109 /// If bumping is enabled, analyses the SSL hello message sent by squid OpenSSL
 110 /// subsystem (step3 bumping step) against bumping mode:
 111 ///   * Peek mode:  Send client hello message instead of the openSSL generated
 112 ///                 hello message and normaly denies bumping and allow only
 113 ///                 splice or terminate the SSL connection
 114 ///   * Stare mode: Sends the openSSL generated hello message and normaly
 115 ///                 denies splicing and allow bump or terminate the SSL
 116 ///                 connection
 117 ///  If SQUID_USE_OPENSSL_HELLO_OVERWRITE_HACK is enabled also checks if the
 118 ///  openSSL library features are compatible with the features reported in
 119 ///  web client SSL hello message and if it is, overwrites the openSSL SSL
 120 ///  object members to replace hello message with web client hello message.
 121 ///  This is may allow bumping in peek mode and splicing in stare mode after
 122 ///  the server hello message received.
 123 class ServerBio: public Bio
 124 {
 125 public:
 126     explicit ServerBio(const int anFd);
 127
 128     /// The ServerBio version of the Ssl::Bio::stateChanged method
 129     virtual void stateChanged(const SSL *ssl, int where, int ret);
 130     /// The ServerBio version of the Ssl::Bio::write method
 131     /// If a clientRandom number is set then rewrites the raw hello message
 132     /// "client random" field with the provided random number.
 133     /// It may buffer the output packets.
 134     virtual int write(const char *buf, int size, BIO *table);
 135     /// The ServerBio version of the Ssl::Bio::read method
 136     /// If the record flag is set then append the data to the rbuf member
 137     virtual int read(char *buf, int size, BIO *table);
 138     /// The ServerBio version of the Ssl::Bio::flush method.
 139     /// Flushes any buffered data
 140     virtual void flush(BIO *table);
 141     /// Sets the random number to use in client SSL HELLO message
 142     void setClientFeatures(Security::TlsDetails::Pointer const &details, SBuf const &hello);
 143
 144     bool resumingSession();
 145
 146     /// The write hold state
 147     bool holdWrite() const {return holdWrite_;}
 148     /// Enables or disables the write hold state
 149     void holdWrite(bool h) {holdWrite_ = h;}
 150     /// The read hold state
 151     bool holdRead() const {return holdRead_;}
 152     /// Enables or disables the read hold state
 153     void holdRead(bool h) {holdRead_ = h;}
 154     /// Enables or disables the input data recording, for internal analysis.
 155     void recordInput(bool r) {record_ = r;}
 156     /// Whether we can splice or not the SSL stream
 157     bool canSplice() {return allowSplice;}
 158     /// Whether we can bump or not the SSL stream
 159     bool canBump() {return allowBump;}
 160     /// The bumping mode
 161     void mode(Ssl::BumpMode m) {bumpMode_ = m;}
 162     Ssl::BumpMode bumpMode() {return bumpMode_;} ///< return the bumping mode
 163
 164     /// \retval true if the Server hello message received
 165     bool gotHello() const { return (parsedHandshake && !parseError); }
 166
 167     /// Return true if the Server Hello parsing failed
 168     bool gotHelloFailed() const { return (parsedHandshake && parseError); }
 169
 170     /// \return the server certificates list if received and parsed correctly
 171     const Security::CertList &serverCertificatesIfAny() { return parser_.serverCertificates; }
 172
 173     /// \return the TLS Details advertised by TLS server.
 174     const Security::TlsDetails::Pointer &receivedHelloDetails() const {return parser_.details;}
 175
 176 private:
 177     int readAndGive(char *buf, const int size, BIO *table);
 178     int readAndParse(char *buf, const int size, BIO *table);
 179     int readAndBuffer(BIO *table);
 180     int giveBuffered(char *buf, const int size);
 181
 182     /// SSL client features extracted from ClientHello message or SSL object
 183     Security::TlsDetails::Pointer clientTlsDetails;
 184     /// TLS client hello message, used to adapt our tls Hello message to the server
 185     SBuf clientSentHello;
 186     SBuf helloMsg; ///< Used to buffer output data.
 187     mb_size_t  helloMsgSize;
 188     bool helloBuild; ///< True if the client hello message sent to the server
 189     bool allowSplice; ///< True if the SSL stream can be spliced
 190     bool allowBump;  ///< True if the SSL stream can be bumped
 191     bool holdWrite_;  ///< The write hold state of the bio.
 192     bool holdRead_;  ///< The read hold state of the bio.
 193     bool record_; ///< If true the input data recorded to rbuf for internal use
 194     bool parsedHandshake; ///< whether we are done parsing TLS Hello
 195     bool parseError; ///< error while parsing server hello message
 196     Ssl::BumpMode bumpMode_;
 197
 198     /// The size of data stored in rbuf which passed to the openSSL
 199     size_t rbufConsumePos;
 200     Security::HandshakeParser parser_; ///< The TLS/SSL messages parser.
 201 };
 202
 203 } // namespace Ssl
 204
 205 void
 206 applyTlsDetailsToSSL(SSL *ssl, Security::TlsDetails::Pointer const &details, Ssl::BumpMode bumpMode);
 207
 208 #endif /* USE_OPENSSL */
 209 #endif /* SQUID_SSL_BIO_H */
 210