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Diffstat (limited to '')
| -rw-r--r-- | src/tls/tls_prng_exch.c | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/src/tls/tls_prng_exch.c b/src/tls/tls_prng_exch.c new file mode 100644 index 0000000..31523a3 --- /dev/null +++ b/src/tls/tls_prng_exch.c @@ -0,0 +1,142 @@ +/*++ +/* NAME +/* tls_prng_exch 3 +/* SUMMARY +/* maintain PRNG exchange file +/* SYNOPSIS +/* #include <tls_prng_src.h> +/* +/* TLS_PRNG_SRC *tls_prng_exch_open(name, timeout) +/* const char *name; +/* int timeout; +/* +/* void tls_prng_exch_update(fh, length) +/* TLS_PRNG_SRC *fh; +/* size_t length; +/* +/* void tls_prng_exch_close(fh) +/* TLS_PRNG_SRC *fh; +/* DESCRIPTION +/* tls_prng_exch_open() opens the specified PRNG exchange file +/* and returns a handle that should be used with all subsequent +/* access. +/* +/* tls_prng_exch_update() reads the requested number of bytes +/* from the PRNG exchange file, updates the OpenSSL PRNG, and +/* writes the requested number of bytes to the exchange file. +/* The file is locked for exclusive access. +/* +/* tls_prng_exch_close() closes the specified PRNG exchange +/* file and releases memory that was allocated for the handle. +/* +/* Arguments: +/* .IP name +/* The name of the PRNG exchange file. +/* .IP length +/* The number of bytes to read from/write to the entropy file. +/* .IP timeout +/* Time limit on individual I/O operations. +/* DIAGNOSTICS +/* All errors are fatal. +/* LICENSE +/* .ad +/* .fi +/* The Secure Mailer license must be distributed with this software. +/* AUTHOR(S) +/* Wietse Venema +/* IBM T.J. Watson Research +/* P.O. Box 704 +/* Yorktown Heights, NY 10598, USA +/*--*/ + +/* System library. */ + +#include <sys_defs.h> +#include <fcntl.h> +#include <unistd.h> +#include <limits.h> + +/* OpenSSL library. */ + +#ifdef USE_TLS +#include <openssl/rand.h> /* For the PRNG */ + +/* Utility library. */ + +#include <msg.h> +#include <mymalloc.h> +#include <iostuff.h> +#include <myflock.h> + +/* TLS library. */ + +#include <tls_prng.h> + +/* Application specific. */ + +#define TLS_PRNG_EXCH_SIZE 1024 /* XXX Why not configurable? */ + +/* tls_prng_exch_open - open PRNG exchange file */ + +TLS_PRNG_SRC *tls_prng_exch_open(const char *name) +{ + const char *myname = "tls_prng_exch_open"; + TLS_PRNG_SRC *eh; + int fd; + + if ((fd = open(name, O_RDWR | O_CREAT, 0600)) < 0) + msg_fatal("%s: cannot open PRNG exchange file %s: %m", myname, name); + eh = (TLS_PRNG_SRC *) mymalloc(sizeof(*eh)); + eh->fd = fd; + eh->name = mystrdup(name); + eh->timeout = 0; + if (msg_verbose) + msg_info("%s: opened PRNG exchange file %s", myname, name); + return (eh); +} + +/* tls_prng_exch_update - update PRNG exchange file */ + +void tls_prng_exch_update(TLS_PRNG_SRC *eh) +{ + unsigned char buffer[TLS_PRNG_EXCH_SIZE]; + ssize_t count; + + /* + * Update the PRNG exchange file. Since other processes may have added + * entropy, we use a read-stir-write cycle. + */ + if (myflock(eh->fd, INTERNAL_LOCK, MYFLOCK_OP_EXCLUSIVE) != 0) + msg_fatal("cannot lock PRNG exchange file %s: %m", eh->name); + if (lseek(eh->fd, 0, SEEK_SET) < 0) + msg_fatal("cannot seek PRNG exchange file %s: %m", eh->name); + if ((count = read(eh->fd, buffer, sizeof(buffer))) < 0) + msg_fatal("cannot read PRNG exchange file %s: %m", eh->name); + + if (count > 0) + RAND_seed(buffer, count); + RAND_bytes(buffer, sizeof(buffer)); + + if (lseek(eh->fd, 0, SEEK_SET) < 0) + msg_fatal("cannot seek PRNG exchange file %s: %m", eh->name); + if (write(eh->fd, buffer, sizeof(buffer)) != sizeof(buffer)) + msg_fatal("cannot write PRNG exchange file %s: %m", eh->name); + if (myflock(eh->fd, INTERNAL_LOCK, MYFLOCK_OP_NONE) != 0) + msg_fatal("cannot unlock PRNG exchange file %s: %m", eh->name); +} + +/* tls_prng_exch_close - close PRNG exchange file */ + +void tls_prng_exch_close(TLS_PRNG_SRC *eh) +{ + const char *myname = "tls_prng_exch_close"; + + if (close(eh->fd) < 0) + msg_fatal("close PRNG exchange file %s: %m", eh->name); + if (msg_verbose) + msg_info("%s: closed PRNG exchange file %s", myname, eh->name); + myfree(eh->name); + myfree((void *) eh); +} + +#endif |