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gnupg/common/sysutils.c

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/* sysutils.c - system helpers
* Copyright (C) 1998, 1999, 2000, 2001, 2003, 2004,
* 2007, 2008 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* GnuPG is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#ifdef WITHOUT_GNU_PTH /* Give the Makefile a chance to build without Pth. */
# undef HAVE_PTH
# undef USE_GNU_PTH
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#ifdef HAVE_STAT
# include <sys/stat.h>
#endif
#if defined(__linux__) && defined(__alpha__) && __GLIBC__ < 2
# include <asm/sysinfo.h>
# include <asm/unistd.h>
#endif
#ifdef HAVE_SETRLIMIT
# include <time.h>
# include <sys/time.h>
# include <sys/resource.h>
#endif
#ifdef HAVE_W32_SYSTEM
# define WINVER 0x0500 /* Required for AllowSetForegroundWindow. */
# include <windows.h>
#endif
#ifdef HAVE_PTH
# include <pth.h>
#endif
#include <fcntl.h>
#include "util.h"
#include "i18n.h"
#include "sysutils.h"
#define tohex(n) ((n) < 10 ? ((n) + '0') : (((n) - 10) + 'A'))
#if defined(__linux__) && defined(__alpha__) && __GLIBC__ < 2
#warning using trap_unaligned
static int
setsysinfo(unsigned long op, void *buffer, unsigned long size,
int *start, void *arg, unsigned long flag)
{
return syscall(__NR_osf_setsysinfo, op, buffer, size, start, arg, flag);
}
void
trap_unaligned(void)
{
unsigned int buf[2];
buf[0] = SSIN_UACPROC;
buf[1] = UAC_SIGBUS | UAC_NOPRINT;
setsysinfo(SSI_NVPAIRS, buf, 1, 0, 0, 0);
}
#else
void
trap_unaligned(void)
{ /* dummy */
}
#endif
int
disable_core_dumps (void)
{
#ifdef HAVE_DOSISH_SYSTEM
return 0;
#else
# ifdef HAVE_SETRLIMIT
struct rlimit limit;
/* We only set the current limit unless we were not able to
retrieve the old value. */
if (getrlimit (RLIMIT_CORE, &limit))
limit.rlim_max = 0;
limit.rlim_cur = 0;
if( !setrlimit (RLIMIT_CORE, &limit) )
return 0;
if( errno != EINVAL && errno != ENOSYS )
log_fatal (_("can't disable core dumps: %s\n"), strerror(errno) );
#endif
return 1;
#endif
}
int
enable_core_dumps (void)
{
#ifdef HAVE_DOSISH_SYSTEM
return 0;
#else
# ifdef HAVE_SETRLIMIT
struct rlimit limit;
if (getrlimit (RLIMIT_CORE, &limit))
return 1;
limit.rlim_cur = limit.rlim_max;
setrlimit (RLIMIT_CORE, &limit);
return 1; /* We always return true because this function is
merely a debugging aid. */
# endif
return 1;
#endif
}
/* Return a string which is used as a kind of process ID */
const byte *
get_session_marker( size_t *rlen )
{
static byte marker[SIZEOF_UNSIGNED_LONG*2];
static int initialized;
if ( !initialized ) {
volatile ulong aa, bb; /* we really want the uninitialized value */
ulong a, b;
initialized = 1;
/* Although this marker is guessable it is not easy to use
* for a faked control packet because an attacker does not
* have enough control about the time the verification does
* take place. Of course, we can add just more random but
* than we need the random generator even for verification
* tasks - which does not make sense. */
a = aa ^ (ulong)getpid();
b = bb ^ (ulong)time(NULL);
memcpy( marker, &a, SIZEOF_UNSIGNED_LONG );
memcpy( marker+SIZEOF_UNSIGNED_LONG, &b, SIZEOF_UNSIGNED_LONG );
}
*rlen = sizeof(marker);
return marker;
}
#if 0 /* not yet needed - Note that this will require inclusion of
cmacros.am in Makefile.am */
int
check_permissions(const char *path,int extension,int checkonly)
{
#if defined(HAVE_STAT) && !defined(HAVE_DOSISH_SYSTEM)
char *tmppath;
struct stat statbuf;
int ret=1;
int isdir=0;
if(opt.no_perm_warn)
return 0;
if(extension && path[0]!=DIRSEP_C)
{
if(strchr(path,DIRSEP_C))
tmppath=make_filename(path,NULL);
else
tmppath=make_filename(GNUPG_LIBDIR,path,NULL);
}
else
tmppath=m_strdup(path);
/* It's okay if the file doesn't exist */
if(stat(tmppath,&statbuf)!=0)
{
ret=0;
goto end;
}
isdir=S_ISDIR(statbuf.st_mode);
/* Per-user files must be owned by the user. Extensions must be
owned by the user or root. */
if((!extension && statbuf.st_uid != getuid()) ||
(extension && statbuf.st_uid!=0 && statbuf.st_uid!=getuid()))
{
if(!checkonly)
log_info(_("Warning: unsafe ownership on %s \"%s\"\n"),
isdir?"directory":extension?"extension":"file",path);
goto end;
}
/* This works for both directories and files - basically, we don't
care what the owner permissions are, so long as the group and
other permissions are 0 for per-user files, and non-writable for
extensions. */
if((extension && (statbuf.st_mode & (S_IWGRP|S_IWOTH)) !=0) ||
(!extension && (statbuf.st_mode & (S_IRWXG|S_IRWXO)) != 0))
{
char *dir;
/* However, if the directory the directory/file is in is owned
by the user and is 700, then this is not a problem.
Theoretically, we could walk this test up to the root
directory /, but for the sake of sanity, I'm stopping at one
level down. */
dir= make_dirname (tmppath);
if(stat(dir,&statbuf)==0 && statbuf.st_uid==getuid() &&
S_ISDIR(statbuf.st_mode) && (statbuf.st_mode & (S_IRWXG|S_IRWXO))==0)
{
xfree (dir);
ret=0;
goto end;
}
m_free(dir);
if(!checkonly)
log_info(_("Warning: unsafe permissions on %s \"%s\"\n"),
isdir?"directory":extension?"extension":"file",path);
goto end;
}
ret=0;
end:
m_free(tmppath);
return ret;
#endif /* HAVE_STAT && !HAVE_DOSISH_SYSTEM */
return 0;
}
#endif
/* Wrapper around the usual sleep fucntion. This one won't wake up
before the sleep time has really elapsed. When build with Pth it
merely calls pth_sleep and thus suspends only the current
thread. */
void
gnupg_sleep (unsigned int seconds)
{
#ifdef HAVE_PTH
/* With Pth we force a regular sleep for seconds == 0 so that also
the process will give up its timeslot. */
if (!seconds)
{
# ifdef HAVE_W32_SYSTEM
Sleep (0);
# else
sleep (0);
# endif
}
pth_sleep (seconds);
#else
/* Fixme: make sure that a sleep won't wake up to early. */
# ifdef HAVE_W32_SYSTEM
Sleep (seconds*1000);
# else
sleep (seconds);
# endif
#endif
}
/* This function is a NOP for POSIX systems but required under Windows
as the file handles as returned by OS calls (like CreateFile) are
different from the libc file descriptors (like open). This function
translates system file handles to libc file handles. FOR_WRITE
gives the direction of the handle. */
int
translate_sys2libc_fd (gnupg_fd_t fd, int for_write)
{
#ifdef HAVE_W32_SYSTEM
int x;
if (fd == GNUPG_INVALID_FD)
return -1;
/* Note that _open_osfhandle is currently defined to take and return
a long. */
x = _open_osfhandle ((long)fd, for_write ? 1 : 0);
if (x == -1)
log_error ("failed to translate osfhandle %p\n", (void *) fd);
return x;
#else /*!HAVE_W32_SYSTEM */
return fd;
#endif
}
/* This is the same as translate_sys2libc_fd but takes an integer
which is assumed to be such an system handle. */
int
translate_sys2libc_fd_int (int fd, int for_write)
{
#ifdef HAVE_W32_SYSTEM
if (fd <= 2)
return fd; /* Do not do this for error, stdin, stdout, stderr. */
return translate_sys2libc_fd ((void*)fd, for_write);
#else
return fd;
#endif
}
/* Replacement for tmpfile(). This is required because the tmpfile
function of Windows' runtime library is broken, insecure, ignores
TMPDIR and so on. In addition we create a file with an inheritable
handle. */
FILE *
gnupg_tmpfile (void)
{
#ifdef HAVE_W32_SYSTEM
int attempts, n;
char buffer[MAX_PATH+7+12+1];
char *name, *p;
HANDLE file;
int pid = GetCurrentProcessId ();
unsigned int value;
int i;
SECURITY_ATTRIBUTES sec_attr;
memset (&sec_attr, 0, sizeof sec_attr );
sec_attr.nLength = sizeof sec_attr;
sec_attr.bInheritHandle = TRUE;
n = GetTempPath (MAX_PATH+1, buffer);
if (!n || n > MAX_PATH || strlen (buffer) > MAX_PATH)
{
errno = ENOENT;
return NULL;
}
p = buffer + strlen (buffer);
p = stpcpy (p, "_gnupg");
/* We try to create the directory but don't care about an error as
it may already exist and the CreateFile would throw an error
anyway. */
CreateDirectory (buffer, NULL);
*p++ = '\\';
name = p;
for (attempts=0; attempts < 10; attempts++)
{
p = name;
value = (GetTickCount () ^ ((pid<<16) & 0xffff0000));
for (i=0; i < 8; i++)
{
*p++ = tohex (((value >> 28) & 0x0f));
value <<= 4;
}
strcpy (p, ".tmp");
file = CreateFile (buffer,
GENERIC_READ | GENERIC_WRITE,
0,
&sec_attr,
CREATE_NEW,
FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_DELETE_ON_CLOSE,
NULL);
if (file != INVALID_HANDLE_VALUE)
{
FILE *fp;
int fd = _open_osfhandle ((long)file, 0);
if (fd == -1)
{
CloseHandle (file);
return NULL;
}
fp = fdopen (fd, "w+b");
if (!fp)
{
int save = errno;
close (fd);
errno = save;
return NULL;
}
return fp;
}
Sleep (1); /* One ms as this is the granularity of GetTickCount. */
}
errno = ENOENT;
return NULL;
#else /*!HAVE_W32_SYSTEM*/
return tmpfile ();
#endif /*!HAVE_W32_SYSTEM*/
}
/* Make sure that the standard file descriptors are opened. Obviously
some folks close them before an exec and the next file we open will
get one of them assigned and thus any output (i.e. diagnostics) end
up in that file (e.g. the trustdb). Not actually a gpg problem as
this will hapen with almost all utilities when called in a wrong
way. However we try to minimize the damage here and raise
awareness of the problem.
Must be called before we open any files! */
void
gnupg_reopen_std (const char *pgmname)
{
#if defined(HAVE_STAT) && !defined(HAVE_W32_SYSTEM)
struct stat statbuf;
int did_stdin = 0;
int did_stdout = 0;
int did_stderr = 0;
FILE *complain;
if (fstat (STDIN_FILENO, &statbuf) == -1 && errno ==EBADF)
{
if (open ("/dev/null",O_RDONLY) == STDIN_FILENO)
did_stdin = 1;
else
did_stdin = 2;
}
if (fstat (STDOUT_FILENO, &statbuf) == -1 && errno == EBADF)
{
if (open ("/dev/null",O_WRONLY) == STDOUT_FILENO)
did_stdout = 1;
else
did_stdout = 2;
}
if (fstat (STDERR_FILENO, &statbuf)==-1 && errno==EBADF)
{
if (open ("/dev/null", O_WRONLY) == STDERR_FILENO)
did_stderr = 1;
else
did_stderr = 2;
}
/* It's hard to log this sort of thing since the filehandle we would
complain to may be closed... */
if (!did_stderr)
complain = stderr;
else if (!did_stdout)
complain = stdout;
else
complain = NULL;
if (complain)
{
if (did_stdin == 1)
fprintf (complain, "%s: WARNING: standard input reopened\n", pgmname);
if (did_stdout == 1)
fprintf (complain, "%s: WARNING: standard output reopened\n", pgmname);
if (did_stderr == 1)
fprintf (complain, "%s: WARNING: standard error reopened\n", pgmname);
if (did_stdin == 2 || did_stdout == 2 || did_stderr == 2)
fprintf(complain,"%s: fatal: unable to reopen standard input,"
" output, or error\n", pgmname);
}
if (did_stdin == 2 || did_stdout == 2 || did_stderr == 2)
exit (3);
#endif /* HAVE_STAT && !HAVE_W32_SYSTEM */
}
/* Hack required for Windows. */
void
gnupg_allow_set_foregound_window (pid_t pid)
{
if (!pid || pid == (pid_t)(-1))
log_info ("%s called with invalid pid %lu\n",
"gnupg_allow_set_foregound_window", (unsigned long)pid);
#ifdef HAVE_W32_SYSTEM
else if (!AllowSetForegroundWindow (pid))
log_info ("AllowSetForegroundWindow(%lu) failed: %s\n",
(unsigned long)pid, w32_strerror (-1));
#endif
}
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