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gnupg/cipher/rndunix.c

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/****************************************************************************
* *
* BeOS Randomness-Gathering Code *
* Copyright Peter Gutmann, Paul Kendall, and Chris Wedgwood 1996-1998 *
* Copyright (C) 1998, 1999 Werner Koch
* *
****************************************************************************/
/* General includes */
#include <config.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
/* OS-specific includes */
#ifdef __osf__
/* Somewhere in the morass of system-specific cruft which OSF/1 pulls in
* via the following includes are various endianness defines, so we
* undefine the cryptlib ones, which aren't really needed for this module
* anyway */
#undef BIG_ENDIAN
#undef LITTLE_ENDIAN
#endif /* __osf__ */
#include <unistd.h>
#include <fcntl.h>
#include <pwd.h>
#ifndef __QNX__
#include <sys/errno.h>
#include <sys/ipc.h>
#endif /* __QNX__ */
#include <sys/time.h> /* SCO and SunOS need this before resource.h */
#ifndef __QNX__
#include <sys/resource.h>
#endif /* __QNX__ */
#ifdef _AIX
#include <sys/select.h>
#endif /* _AIX */
#ifndef __QNX__
#include <sys/shm.h>
#include <sys/signal.h>
#endif /* __QNX__ */
#include <sys/stat.h>
#include <sys/types.h> /* Verschiedene komische Typen */
#if defined( __hpux ) && ( OS_VERSION == 9 )
#include <vfork.h>
#endif /* __hpux 9.x, after that it's in unistd.h */
#include <sys/wait.h>
/* #include <kitchensink.h> */
#include <errno.h>
#include "types.h" /* for byte and u32 typedefs */
#ifndef IS_MODULE
#include "dynload.h"
#endif
#include "util.h"
#ifndef EAGAIN
#define EAGAIN EWOULDBLOCK
#endif
#define GATHER_BUFSIZE 49152 /* Usually about 25K are filled */
/* The structure containing information on random-data sources. Each
* record contains the source and a relative estimate of its usefulness
* (weighting) which is used to scale the number of kB of output from the
* source (total = data_bytes / usefulness). Usually the weighting is in the
* range 1-3 (or 0 for especially useless sources), resulting in a usefulness
* rating of 1...3 for each kB of source output (or 0 for the useless
* sources).
*
* If the source is constantly changing (certain types of network statistics
* have this characteristic) but the amount of output is small, the weighting
* is given as a negative value to indicate that the output should be treated
* as if a minimum of 1K of output had been obtained. If the source produces
* a lot of output then the scale factor is fractional, resulting in a
* usefulness rating of < 1 for each kB of source output.
*
* In order to provide enough randomness to satisfy the requirements for a
* slow poll, we need to accumulate at least 20 points of usefulness (a
* typical system should get about 30 points).
*
* Some potential options are missed out because of special considerations.
* pstat -i and pstat -f can produce amazing amounts of output (the record
* is 600K on an Oracle server) which floods the buffer and doesn't yield
* anything useful (apart from perhaps increasing the entropy of the vmstat
* output a bit), so we don't bother with this. pstat in general produces
* quite a bit of output, but it doesn't change much over time, so it gets
* very low weightings. netstat -s produces constantly-changing output but
* also produces quite a bit of it, so it only gets a weighting of 2 rather
* than 3. The same holds for netstat -in, which gets 1 rather than 2.
*
* Some binaries are stored in different locations on different systems so
* alternative paths are given for them. The code sorts out which one to
* run by itself, once it finds an exectable somewhere it moves on to the
* next source. The sources are arranged roughly in their order of
* usefulness, occasionally sources which provide a tiny amount of
* relatively useless data are placed ahead of ones which provide a large
* amount of possibly useful data because another 100 bytes can't hurt, and
* it means the buffer won't be swamped by one or two high-output sources.
* All the high-output sources are clustered towards the end of the list
* for this reason. Some binaries are checked for in a certain order, for
* example under Slowaris /usr/ucb/ps understands aux as an arg, but the
* others don't. Some systems have conditional defines enabling alternatives
* to commands which don't understand the usual options but will provide
* enough output (in the form of error messages) to look like they're the
* real thing, causing alternative options to be skipped (we can't check the
* return either because some commands return peculiar, non-zero status even
* when they're working correctly).
*
* In order to maximise use of the buffer, the code performs a form of run-
* length compression on its input where a repeated sequence of bytes is
* replaced by the occurrence count mod 256. Some commands output an awful
* lot of whitespace, this measure greatly increases the amount of data we
* can fit in the buffer.
*
* When we scale the weighting using the SC() macro, some preprocessors may
* give a division by zero warning for the most obvious expression
* 'weight ? 1024 / weight : 0' (and gcc 2.7.2.2 dies with a division by zero
* trap), so we define a value SC_0 which evaluates to zero when fed to
* '1024 / SC_0' */
#define SC( weight ) ( 1024 / weight ) /* Scale factor */
#define SC_0 16384 /* SC( SC_0 ) evalutes to 0 */
static struct RI {
const char *path; /* Path to check for existence of source */
const char *arg; /* Args for source */
const int usefulness; /* Usefulness of source */
FILE *pipe; /* Pipe to source as FILE * */
int pipeFD; /* Pipe to source as FD */
pid_t pid; /* pid of child for waitpid() */
int length; /* Quantity of output produced */
const int hasAlternative; /* Whether source has alt.location */
} dataSources[] = {
{ "/bin/vmstat", "-s", SC(-3), NULL, 0, 0, 0, 1 },
{ "/usr/bin/vmstat", "-s", SC(-3), NULL, 0, 0, 0, 0},
{ "/bin/vmstat", "-c", SC(-3), NULL, 0, 0, 0, 1 },
{ "/usr/bin/vmstat", "-c", SC(-3), NULL, 0, 0, 0, 0},
{ "/usr/bin/pfstat", NULL, SC(-2), NULL, 0, 0, 0, 0},
{ "/bin/vmstat", "-i", SC(-2), NULL, 0, 0, 0, 1 },
{ "/usr/bin/vmstat", "-i", SC(-2), NULL, 0, 0, 0, 0},
{ "/usr/ucb/netstat", "-s", SC(2), NULL, 0, 0, 0, 1 },
{ "/usr/bin/netstat", "-s", SC(2), NULL, 0, 0, 0, 1 },
{ "/usr/sbin/netstat", "-s", SC(2), NULL, 0, 0, 0, 1},
{ "/usr/etc/netstat", "-s", SC(2), NULL, 0, 0, 0, 0},
{ "/usr/bin/nfsstat", NULL, SC(2), NULL, 0, 0, 0, 0},
{ "/usr/ucb/netstat", "-m", SC(-1), NULL, 0, 0, 0, 1 },
{ "/usr/bin/netstat", "-m", SC(-1), NULL, 0, 0, 0, 1 },
{ "/usr/sbin/netstat", "-m", SC(-1), NULL, 0, 0, 0, 1 },
{ "/usr/etc/netstat", "-m", SC(-1), NULL, 0, 0, 0, 0 },
{ "/bin/netstat", "-in", SC(-1), NULL, 0, 0, 0, 1 },
{ "/usr/ucb/netstat", "-in", SC(-1), NULL, 0, 0, 0, 1 },
{ "/usr/bin/netstat", "-in", SC(-1), NULL, 0, 0, 0, 1 },
{ "/usr/sbin/netstat", "-in", SC(-1), NULL, 0, 0, 0, 1},
{ "/usr/etc/netstat", "-in", SC(-1), NULL, 0, 0, 0, 0},
{ "/usr/sbin/snmp_request", "localhost public get 1.3.6.1.2.1.7.1.0",
SC(-1), NULL, 0, 0, 0, 0 }, /* UDP in */
{ "/usr/sbin/snmp_request", "localhost public get 1.3.6.1.2.1.7.4.0",
SC(-1), NULL, 0, 0, 0, 0 }, /* UDP out */
{ "/usr/sbin/snmp_request", "localhost public get 1.3.6.1.2.1.4.3.0",
SC(-1), NULL, 0, 0, 0, 0 }, /* IP ? */
{ "/usr/sbin/snmp_request", "localhost public get 1.3.6.1.2.1.6.10.0",
SC(-1), NULL, 0, 0, 0, 0 }, /* TCP ? */
{ "/usr/sbin/snmp_request", "localhost public get 1.3.6.1.2.1.6.11.0",
SC(-1), NULL, 0, 0, 0, 0 }, /* TCP ? */
{ "/usr/sbin/snmp_request", "localhost public get 1.3.6.1.2.1.6.13.0",
SC(-1), NULL, 0, 0, 0, 0 }, /* TCP ? */
{ "/usr/bin/mpstat", NULL, SC(1), NULL, 0, 0, 0, 0 },
{ "/usr/bin/w", NULL, SC(1), NULL, 0, 0, 0, 1 },
{ "/usr/bsd/w", NULL, SC(1), NULL, 0, 0, 0, 0 },
{ "/usr/bin/df", NULL, SC(1), NULL, 0, 0, 0, 1 },
{ "/bin/df", NULL, SC(1), NULL, 0, 0, 0, 0 },
{ "/usr/sbin/portstat", NULL, SC(1), NULL, 0, 0, 0, 0 },
{ "/usr/bin/iostat", NULL, SC(SC_0), NULL, 0, 0, 0, 0 },
{ "/usr/bin/uptime", NULL, SC(SC_0), NULL, 0, 0, 0, 1 },
{ "/usr/bsd/uptime", NULL, SC(SC_0), NULL, 0, 0, 0, 0 },
{ "/bin/vmstat", "-f", SC(SC_0), NULL, 0, 0, 0, 1 },
{ "/usr/bin/vmstat", "-f", SC(SC_0), NULL, 0, 0, 0, 0 },
{ "/bin/vmstat", NULL, SC(SC_0), NULL, 0, 0, 0, 1 },
{ "/usr/bin/vmstat", NULL, SC(SC_0), NULL, 0, 0, 0, 0 },
{ "/usr/ucb/netstat", "-n", SC(0.5), NULL, 0, 0, 0, 1 },
{ "/usr/bin/netstat", "-n", SC(0.5), NULL, 0, 0, 0, 1 },
{ "/usr/sbin/netstat", "-n", SC(0.5), NULL, 0, 0, 0, 1 },
{ "/usr/etc/netstat", "-n", SC(0.5), NULL, 0, 0, 0, 0 },
#if defined( __sgi ) || defined( __hpux )
{ "/bin/ps", "-el", SC(0.3), NULL, 0, 0, 0, 1 },
#endif /* __sgi || __hpux */
{ "/usr/ucb/ps", "aux", SC(0.3), NULL, 0, 0, 0, 1 },
{ "/usr/bin/ps", "aux", SC(0.3), NULL, 0, 0, 0, 1 },
{ "/bin/ps", "aux", SC(0.3), NULL, 0, 0, 0, 0 },
{ "/usr/bin/ipcs", "-a", SC(0.5), NULL, 0, 0, 0, 1 },
{ "/bin/ipcs", "-a", SC(0.5), NULL, 0, 0, 0, 0 },
/* Unreliable source, depends on system usage */
{ "/etc/pstat", "-p", SC(0.5), NULL, 0, 0, 0, 1 },
{ "/bin/pstat", "-p", SC(0.5), NULL, 0, 0, 0, 0 },
{ "/etc/pstat", "-S", SC(0.2), NULL, 0, 0, 0, 1 },
{ "/bin/pstat", "-S", SC(0.2), NULL, 0, 0, 0, 0 },
{ "/etc/pstat", "-v", SC(0.2), NULL, 0, 0, 0, 1 },
{ "/bin/pstat", "-v", SC(0.2), NULL, 0, 0, 0, 0 },
{ "/etc/pstat", "-x", SC(0.2), NULL, 0, 0, 0, 1 },
{ "/bin/pstat", "-x", SC(0.2), NULL, 0, 0, 0, 0 },
{ "/etc/pstat", "-t", SC(0.1), NULL, 0, 0, 0, 1 },
{ "/bin/pstat", "-t", SC(0.1), NULL, 0, 0, 0, 0 },
/* pstat is your friend */
{ "/usr/bin/last", "-n 50", SC(0.3), NULL, 0, 0, 0, 1 },
#ifdef __sgi
{ "/usr/bsd/last", "-50", SC(0.3), NULL, 0, 0, 0, 0 },
#endif /* __sgi */
#ifdef __hpux
{ "/etc/last", "-50", SC(0.3), NULL, 0, 0, 0, 0 },
#endif /* __hpux */
{ "/usr/bsd/last", "-n 50", SC(0.3), NULL, 0, 0, 0, 0 },
{ "/usr/sbin/snmp_request", "localhost public get 1.3.6.1.2.1.5.1.0",
SC(0.1), NULL, 0, 0, 0, 0 }, /* ICMP ? */
{ "/usr/sbin/snmp_request", "localhost public get 1.3.6.1.2.1.5.3.0",
SC(0.1), NULL, 0, 0, 0, 0 }, /* ICMP ? */
{ "/etc/arp", "-a", SC(0.1), NULL, 0, 0, 0, 1 },
{ "/usr/etc/arp", "-a", SC(0.1), NULL, 0, 0, 0, 1 },
{ "/usr/bin/arp", "-a", SC(0.1), NULL, 0, 0, 0, 1 },
{ "/usr/sbin/arp", "-a", SC(0.1), NULL, 0, 0, 0, 0 },
{ "/usr/sbin/ripquery", "-nw 1 127.0.0.1",
SC(0.1), NULL, 0, 0, 0, 0 },
{ "/bin/lpstat", "-t", SC(0.1), NULL, 0, 0, 0, 1 },
{ "/usr/bin/lpstat", "-t", SC(0.1), NULL, 0, 0, 0, 1 },
{ "/usr/ucb/lpstat", "-t", SC(0.1), NULL, 0, 0, 0, 0 },
{ "/usr/bin/tcpdump", "-c 5 -efvvx", SC(1), NULL, 0, 0, 0, 0 },
/* This is very environment-dependant. If network traffic is low, it'll
* probably time out before delivering 5 packets, which is OK because
* it'll probably be fixed stuff like ARP anyway */
{ "/usr/sbin/advfsstat", "-b usr_domain",
SC(SC_0), NULL, 0, 0, 0, 0},
{ "/usr/sbin/advfsstat", "-l 2 usr_domain",
SC(0.5), NULL, 0, 0, 0, 0},
{ "/usr/sbin/advfsstat", "-p usr_domain",
SC(SC_0), NULL, 0, 0, 0, 0},
/* This is a complex and screwball program. Some systems have things
* like rX_dmn, x = integer, for RAID systems, but the statistics are
* pretty dodgy */
#if 0
/* The following aren't enabled since they're somewhat slow and not very
* unpredictable, however they give an indication of the sort of sources
* you can use (for example the finger might be more useful on a
* firewalled internal network) */
{ "/usr/bin/finger", "@ml.media.mit.edu", SC(0.9), NULL, 0, 0, 0, 0 },
{ "/usr/local/bin/wget", "-O - http://lavarand.sgi.com/block.html",
SC(0.9), NULL, 0, 0, 0, 0 },
{ "/bin/cat", "/usr/spool/mqueue/syslog", SC(0.9), NULL, 0, 0, 0, 0 },
#endif /* 0 */
{ NULL, NULL, 0, NULL, 0, 0, 0, 0 }
};
static byte *gather_buffer; /* buffer for gathering random noise */
static int gather_buffer_size; /* size of the memory buffer */
static uid_t gatherer_uid;
/* The message structure used to communicate with the parent */
typedef struct {
int usefulness; /* usefulness of data */
int ndata; /* valid bytes in data */
char data[500]; /* gathered data */
} GATHER_MSG;
/* Under SunOS popen() doesn't record the pid of the child process. When
* pclose() is called, instead of calling waitpid() for the correct child, it
* calls wait() repeatedly until the right child is reaped. The problem is
* that this reaps any other children that happen to have died at that
* moment, and when their pclose() comes along, the process hangs forever.
* The fix is to use a wrapper for popen()/pclose() which saves the pid in
* the dataSources structure (code adapted from GNU-libc's popen() call).
*
* Aut viam inveniam aut faciam */
static FILE *
my_popen(struct RI *entry)
{
int pipedes[2];
FILE *stream;
/* Create the pipe */
if (pipe(pipedes) < 0)
return (NULL);
/* Fork off the child ("vfork() is like an OS orgasm. All OS's want to
* do it, but most just end up faking it" - Chris Wedgwood). If your OS
* supports it, you should try to use vfork() here because it's somewhat
* more efficient */
#if defined( sun ) || defined( __ultrix__ ) || defined( __osf__ ) || \
defined(__hpux)
entry->pid = vfork();
#else /* */
entry->pid = fork();
#endif /* Unixen which have vfork() */
if (entry->pid == (pid_t) - 1) {
/* The fork failed */
close(pipedes[0]);
close(pipedes[1]);
return (NULL);
}
if (entry->pid == (pid_t) 0) {
struct passwd *passwd;
/* We are the child. Make the read side of the pipe be stdout */
if (dup2(pipedes[STDOUT_FILENO], STDOUT_FILENO) < 0)
exit(127);
/* Now that everything is set up, give up our permissions to make
* sure we don't read anything sensitive. If the getpwnam() fails,
* we default to -1, which is usually nobody */
if (gatherer_uid == (uid_t)-1 && \
(passwd = getpwnam("nobody")) != NULL)
gatherer_uid = passwd->pw_uid;
setuid(gatherer_uid);
/* Close the pipe descriptors */
close(pipedes[STDIN_FILENO]);
close(pipedes[STDOUT_FILENO]);
/* Try and exec the program */
execl(entry->path, entry->path, entry->arg, NULL);
/* Die if the exec failed */
exit(127);
}
/* We are the parent. Close the irrelevant side of the pipe and open
* the relevant side as a new stream. Mark our side of the pipe to
* close on exec, so new children won't see it */
close(pipedes[STDOUT_FILENO]);
fcntl(pipedes[STDIN_FILENO], F_SETFD, FD_CLOEXEC);
stream = fdopen(pipedes[STDIN_FILENO], "r");
if (stream == NULL) {
int savedErrno = errno;
/* The stream couldn't be opened or the child structure couldn't be
* allocated. Kill the child and close the other side of the pipe */
kill(entry->pid, SIGKILL);
if (stream == NULL)
close(pipedes[STDOUT_FILENO]);
else
fclose(stream);
waitpid(entry->pid, NULL, 0);
entry->pid = 0;
errno = savedErrno;
return (NULL);
}
return (stream);
}
static int
my_pclose(struct RI *entry)
{
int status = 0;
if (fclose(entry->pipe))
return (-1);
/* We ignore the return value from the process because some programs
* return funny values which would result in the input being discarded
* even if they executed successfully. This isn't a problem because the
* result data size threshold will filter out any programs which exit
* with a usage message without producing useful output */
if (waitpid(entry->pid, NULL, 0) != entry->pid)
status = -1;
entry->pipe = NULL;
entry->pid = 0;
return (status);
}
/* Unix slow poll (without special support for Linux)
*
* If a few of the randomness sources create a large amount of output then
* the slowPoll() stops once the buffer has been filled (but before all the
* randomness sources have been sucked dry) so that the 'usefulness' factor
* remains below the threshold. For this reason the gatherer buffer has to
* be fairly sizeable on moderately loaded systems. This is something of a
* bug since the usefulness should be influenced by the amount of output as
* well as the source type */
static int
slow_poll(FILE *dbgfp, int dbgall, size_t *nbytes )
{
int moreSources;
struct timeval tv;
fd_set fds;
#if defined( __hpux )
size_t maxFD = 0;
#else
int maxFD = 0;
#endif /* OS-specific brokenness */
int bufPos, i, usefulness = 0;
/* Fire up each randomness source */
FD_ZERO(&fds);
for (i = 0; dataSources[i].path != NULL; i++) {
/* Since popen() is a fairly heavy function, we check to see whether
* the executable exists before we try to run it */
if (access(dataSources[i].path, X_OK)) {
if( dbgfp && dbgall )
fprintf(dbgfp, "%s not present%s\n", dataSources[i].path,
dataSources[i].hasAlternative ?
", has alternatives" : "");
dataSources[i].pipe = NULL;
}
else
dataSources[i].pipe = my_popen(&dataSources[i]);
if (dataSources[i].pipe != NULL) {
dataSources[i].pipeFD = fileno(dataSources[i].pipe);
if (dataSources[i].pipeFD > maxFD)
maxFD = dataSources[i].pipeFD;
#ifdef O_NONBLOCK /* Ohhh what a hack (used for Atari) */
fcntl(dataSources[i].pipeFD, F_SETFL, O_NONBLOCK);
#else
#warning O_NONBLOCK is missing
#endif
FD_SET(dataSources[i].pipeFD, &fds);
dataSources[i].length = 0;
/* If there are alternatives for this command, don't try and
* execute them */
while (dataSources[i].hasAlternative) {
if( dbgfp && dbgall )
fprintf(dbgfp, "Skipping %s\n", dataSources[i + 1].path);
i++;
}
}
}
/* Suck all the data we can get from each of the sources */
bufPos = 0;
moreSources = 1;
while (moreSources && bufPos <= gather_buffer_size) {
/* Wait for data to become available from any of the sources, with a
* timeout of 10 seconds. This adds even more randomness since data
* becomes available in a nondeterministic fashion. Kudos to HP's QA
* department for managing to ship a select() which breaks its own
* prototype */
tv.tv_sec = 10;
tv.tv_usec = 0;
#if defined( __hpux ) && ( OS_VERSION == 9 )
if (select(maxFD + 1, (int *)&fds, NULL, NULL, &tv) == -1)
#else /* */
if (select(maxFD + 1, &fds, NULL, NULL, &tv) == -1)
#endif /* __hpux */
break;
/* One of the sources has data available, read it into the buffer */
for (i = 0; dataSources[i].path != NULL; i++) {
if( dataSources[i].pipe && FD_ISSET(dataSources[i].pipeFD, &fds)) {
size_t noBytes;
if ((noBytes = fread(gather_buffer + bufPos, 1,
gather_buffer_size - bufPos,
dataSources[i].pipe)) == 0) {
if (my_pclose(&dataSources[i]) == 0) {
int total = 0;
/* Try and estimate how much entropy we're getting
* from a data source */
if (dataSources[i].usefulness) {
if (dataSources[i].usefulness < 0)
total = (dataSources[i].length + 999)
/ -dataSources[i].usefulness;
else
total = dataSources[i].length
/ dataSources[i].usefulness;
}
if( dbgfp )
fprintf(dbgfp,
"%s %s contributed %d bytes, "
"usefulness = %d\n", dataSources[i].path,
(dataSources[i].arg != NULL) ?
dataSources[i].arg : "",
dataSources[i].length, total);
if( dataSources[i].length )
usefulness += total;
}
dataSources[i].pipe = NULL;
}
else {
int currPos = bufPos;
int endPos = bufPos + noBytes;
/* Run-length compress the input byte sequence */
while (currPos < endPos) {
int ch = gather_buffer[currPos];
/* If it's a single byte, just copy it over */
if (ch != gather_buffer[currPos + 1]) {
gather_buffer[bufPos++] = ch;
currPos++;
}
else {
int count = 0;
/* It's a run of repeated bytes, replace them
* with the byte count mod 256 */
while ((ch == gather_buffer[currPos])
&& currPos < endPos) {
count++;
currPos++;
}
gather_buffer[bufPos++] = count;
noBytes -= count - 1;
}
}
/* Remember the number of (compressed) bytes of input we
* obtained */
dataSources[i].length += noBytes;
}
}
}
/* Check if there is more input available on any of the sources */
moreSources = 0;
FD_ZERO(&fds);
for (i = 0; dataSources[i].path != NULL; i++) {
if (dataSources[i].pipe != NULL) {
FD_SET(dataSources[i].pipeFD, &fds);
moreSources = 1;
}
}
}
if( dbgfp ) {
fprintf(dbgfp, "Got %d bytes, usefulness = %d\n", bufPos, usefulness);
fflush(dbgfp);
}
*nbytes = bufPos;
return usefulness;
}
/****************
* Start the gatherer process which writes messages of
* type GATHERER_MSG to pipedes
*/
static void
start_gatherer( int pipefd )
{
FILE *dbgfp = NULL;
int dbgall;
{
const char *s = getenv("GNUPG_RNDUNIX_DBG");
if( s ) {
dbgfp = (*s=='-' && !s[1])? stdout : fopen(s, "a");
if( !dbgfp )
g10_log_info("can't open debug file `%s': %s\n",
s, strerror(errno) );
else
fprintf(dbgfp,"\nSTART RNDUNIX DEBUG pid=%d\n", (int)getpid());
}
dbgall = !!getenv("GNUPG_RNDUNIX_DBGALL");
}
/* close all files but the ones we need */
{ int nmax, n1, n2, i;
if( (nmax=sysconf( _SC_OPEN_MAX )) < 0 ) {
#ifdef _POSIX_OPEN_MAX
nmax = _POSIX_OPEN_MAX;
#else
nmax = 20; /* assume a reasonable value */
#endif
}
n1 = fileno( stderr );
n2 = dbgfp? fileno( dbgfp ) : -1;
for(i=0; i < nmax; i++ ) {
if( i != n1 && i != n2 && i != pipefd )
close(i);
}
errno = 0;
}
/* Set up the buffer */
gather_buffer_size = GATHER_BUFSIZE;
gather_buffer = malloc( gather_buffer_size );
if( !gather_buffer ) {
g10_log_error("out of core while allocating the gatherer buffer\n");
exit(2);
}
/* Reset the SIGC(H)LD handler to the system default. This is necessary
* because if the program which cryptlib is a part of installs its own
* SIGC(H)LD handler, it will end up reaping the cryptlib children before
* cryptlib can. As a result, my_pclose() will call waitpid() on a
* process which has already been reaped by the installed handler and
* return an error, so the read data won't be added to the randomness
* pool. There are two types of SIGC(H)LD naming, the SysV SIGCLD and
* the BSD/Posix SIGCHLD, so we need to handle either possibility */
#ifdef SIGCLD
signal(SIGCLD, SIG_DFL);
#else
signal(SIGCHLD, SIG_DFL);
#endif
fclose(stderr); /* Arrghh!! It's Stuart code!! */
for(;;) {
GATHER_MSG msg;
size_t nbytes;
const char *p;
msg.usefulness = slow_poll( dbgfp, dbgall, &nbytes );
p = gather_buffer;
while( nbytes ) {
msg.ndata = nbytes > sizeof(msg.data)? sizeof(msg.data) : nbytes;
memcpy( msg.data, p, msg.ndata );
nbytes -= msg.ndata;
p += msg.ndata;
while( write( pipefd, &msg, sizeof(msg) ) != sizeof(msg) ) {
if( errno == EINTR )
continue;
if( errno == EAGAIN ) {
struct timeval tv;
tv.tv_sec = 0;
tv.tv_usec = 50000;
select(0, NULL, NULL, NULL, &tv);
continue;
}
if( errno == EPIPE ) /* parent has exited, so give up */
exit(0);
/* we can't do very much here because stderr is closed */
if( dbgfp )
fprintf(dbgfp, "gatherer can't write to pipe: %s\n",
strerror(errno) );
/* we start a new poll to give the system some time */
nbytes = 0;
break;
}
}
}
/* we are killed when the parent dies */
}
static int
read_a_msg( int fd, GATHER_MSG *msg )
{
char *buffer = (char*)msg;
size_t length = sizeof( *msg );
int n;
do {
do {
n = read(fd, buffer, length );
} while( n == -1 && errno == EINTR );
if( n == -1 )
return -1;
buffer += n;
length -= n;
} while( length );
return 0;
}
static int
gather_random( void (*add)(const void*, size_t, int), int requester,
size_t length, int level )
{
static pid_t gatherer_pid = 0;
static int pipedes[2];
GATHER_MSG msg;
size_t n;
if( !gatherer_pid ) {
/* make sure we are not setuid */
if( getuid() != geteuid() )
BUG();
/* time to start the gatherer process */
if( pipe( pipedes ) ) {
g10_log_error("pipe() failed: %s\n", strerror(errno));
return -1;
}
gatherer_pid = fork();
if( gatherer_pid == -1 ) {
g10_log_error("can't for gatherer process: %s\n", strerror(errno));
return -1;
}
if( !gatherer_pid ) {
start_gatherer( pipedes[1] );
/* oops, can't happen */
return -1;
}
}
/* now read from the gatherer */
while( length ) {
int goodness;
ulong subtract;
if( read_a_msg( pipedes[0], &msg ) ) {
g10_log_error("reading from gatherer pipe failed: %s\n",
strerror(errno));
return -1;
}
if( level > 1 ) {
if( msg.usefulness > 30 )
goodness = 100;
else if ( msg.usefulness )
goodness = msg.usefulness * 100 / 30;
else
goodness = 0;
}
else if( level ) {
if( msg.usefulness > 15 )
goodness = 100;
else if ( msg.usefulness )
goodness = msg.usefulness * 100 / 15;
else
goodness = 0;
}
else
goodness = 100; /* goodness of level 0 is always 100 % */
n = msg.ndata;
if( n > length )
n = length;
(*add)( msg.data, n, requester );
/* this is the trick how e cope with the goodness */
subtract = (ulong)n * goodness / 100;
/* subtract at least 1 byte to avoid infinite loops */
length -= subtract ? subtract : 1;
}
return 0;
}
#ifndef IS_MODULE
static
#endif
const char * const gnupgext_version = "RNDUNIX ($Revision$)";
static struct {
int class;
int version;
void *func;
} func_table[] = {
{ 40, 1, gather_random },
};
/****************
* Enumerate the names of the functions together with informations about
* this function. Set sequence to an integer with a initial value of 0 and
* do not change it.
* If what is 0 all kind of functions are returned.
* Return values: class := class of function:
* 10 = message digest algorithm info function
* 11 = integer with available md algorithms
* 20 = cipher algorithm info function
* 21 = integer with available cipher algorithms
* 30 = public key algorithm info function
* 31 = integer with available pubkey algorithms
* 40 = get read_random_source() function
* 41 = get fast_random_poll function
* version = interface version of the function/pointer
* (currently this is 1 for all functions)
*/
#ifndef IS_MODULE
static
#endif
void *
gnupgext_enum_func( int what, int *sequence, int *class, int *vers )
{
void *ret;
int i = *sequence;
do {
if ( i >= DIM(func_table) || i < 0 ) {
return NULL;
}
*class = func_table[i].class;
*vers = func_table[i].version;
ret = func_table[i].func;
i++;
} while ( what && what != *class );
*sequence = i;
return ret;
}
#ifndef IS_MODULE
void
rndunix_constructor(void)
{
register_internal_cipher_extension( gnupgext_version,
gnupgext_enum_func );
}
#endif
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