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gnupg/g10/exec.c

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/* exec.c - generic call-a-program code
* Copyright (C) 2001, 2002, 2003, 2004, 2005 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>
#include <stdlib.h>
#include <stdarg.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#ifndef EXEC_TEMPFILE_ONLY
#include <sys/wait.h>
#endif
#ifdef HAVE_DOSISH_SYSTEM
#include <windows.h>
#endif
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include "gpg.h"
#include "options.h"
#include "i18n.h"
#include "iobuf.h"
#include "util.h"
#include "mkdtemp.h" /* From gnulib. */
#include "exec.h"
#ifdef NO_EXEC
int exec_write(struct exec_info **info,const char *program,
const char *args_in,const char *name,int writeonly,int binary)
{
log_error(_("no remote program execution supported\n"));
return G10ERR_GENERAL;
}
int exec_read(struct exec_info *info) { return G10ERR_GENERAL; }
int exec_finish(struct exec_info *info) { return G10ERR_GENERAL; }
int set_exec_path(const char *path) { return G10ERR_GENERAL; }
#else /* ! NO_EXEC */
#if defined (_WIN32)
/* This is a nicer system() for windows that waits for programs to
return before returning control to the caller. I hate helpful
computers. */
static int w32_system(const char *command)
{
PROCESS_INFORMATION pi;
STARTUPINFO si;
char *string;
/* We must use a copy of the command as CreateProcess modifies this
argument. */
string=xstrdup(command);
memset(&pi,0,sizeof(pi));
memset(&si,0,sizeof(si));
si.cb=sizeof(si);
if(!CreateProcess(NULL,string,NULL,NULL,FALSE,0,NULL,NULL,&si,&pi))
return -1;
/* Wait for the child to exit */
WaitForSingleObject(pi.hProcess,INFINITE);
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
xfree(string);
return 0;
}
#endif
/* Replaces current $PATH */
int set_exec_path(const char *path)
{
char *p;
p=xmalloc(5+strlen(path)+1);
strcpy(p,"PATH=");
strcat(p,path);
if(DBG_EXTPROG)
log_debug("set_exec_path: %s\n",p);
/* Notice that path is never freed. That is intentional due to the
way putenv() works. This leaks a few bytes if we call
set_exec_path multiple times. */
if(putenv(p)!=0)
return G10ERR_GENERAL;
else
return 0;
}
/* Makes a temp directory and filenames */
static int make_tempdir(struct exec_info *info)
{
char *tmp=opt.temp_dir,*namein=info->name,*nameout;
if(!namein)
namein=info->flags.binary?"tempin" EXTSEP_S "bin":"tempin" EXTSEP_S "txt";
nameout=info->flags.binary?"tempout" EXTSEP_S "bin":"tempout" EXTSEP_S "txt";
/* Make up the temp dir and files in case we need them */
if(tmp==NULL)
{
#if defined (_WIN32)
int err;
tmp=xmalloc(MAX_PATH+2);
err=GetTempPath(MAX_PATH+1,tmp);
if(err==0 || err>MAX_PATH+1)
strcpy(tmp,"c:\\windows\\temp");
else
{
int len=strlen(tmp);
/* GetTempPath may return with \ on the end */
while(len>0 && tmp[len-1]=='\\')
{
tmp[len-1]='\0';
len--;
}
}
#else /* More unixish systems */
tmp=getenv("TMPDIR");
if(tmp==NULL)
{
tmp=getenv("TMP");
if(tmp==NULL)
{
#ifdef __riscos__
tmp="<Wimp$ScrapDir>.GnuPG";
mkdir(tmp,0700); /* Error checks occur later on */
#else
tmp="/tmp";
#endif
}
}
#endif
}
info->tempdir=xmalloc(strlen(tmp)+strlen(DIRSEP_S)+10+1);
sprintf(info->tempdir,"%s" DIRSEP_S "gpg-XXXXXX",tmp);
#if defined (_WIN32)
xfree(tmp);
#endif
if(mkdtemp(info->tempdir)==NULL)
log_error(_("can't create directory `%s': %s\n"),
info->tempdir,strerror(errno));
else
{
info->flags.madedir=1;
info->tempfile_in=xmalloc(strlen(info->tempdir)+
strlen(DIRSEP_S)+strlen(namein)+1);
sprintf(info->tempfile_in,"%s" DIRSEP_S "%s",info->tempdir,namein);
if(!info->flags.writeonly)
{
info->tempfile_out=xmalloc(strlen(info->tempdir)+
strlen(DIRSEP_S)+strlen(nameout)+1);
sprintf(info->tempfile_out,"%s" DIRSEP_S "%s",info->tempdir,nameout);
}
}
return info->flags.madedir?0:G10ERR_GENERAL;
}
/* Expands %i and %o in the args to the full temp files within the
temp directory. */
static int expand_args(struct exec_info *info,const char *args_in)
{
const char *ch=args_in;
unsigned int size,len;
info->flags.use_temp_files=0;
info->flags.keep_temp_files=0;
if(DBG_EXTPROG)
log_debug("expanding string \"%s\"\n",args_in);
size=100;
info->command=xmalloc(size);
len=0;
info->command[0]='\0';
while(*ch!='\0')
{
if(*ch=='%')
{
char *append=NULL;
ch++;
switch(*ch)
{
case 'O':
info->flags.keep_temp_files=1;
/* fall through */
case 'o': /* out */
if(!info->flags.madedir)
{
if(make_tempdir(info))
goto fail;
}
append=info->tempfile_out;
info->flags.use_temp_files=1;
break;
case 'I':
info->flags.keep_temp_files=1;
/* fall through */
case 'i': /* in */
if(!info->flags.madedir)
{
if(make_tempdir(info))
goto fail;
}
append=info->tempfile_in;
info->flags.use_temp_files=1;
break;
case '%':
append="%";
break;
}
if(append)
{
size_t applen=strlen(append);
if(applen+len>size-1)
{
if(applen<100)
applen=100;
size+=applen;
info->command=xrealloc(info->command,size);
}
strcat(info->command,append);
len+=strlen(append);
}
}
else
{
if(len==size-1) /* leave room for the \0 */
{
size+=100;
info->command=xrealloc(info->command,size);
}
info->command[len++]=*ch;
info->command[len]='\0';
}
ch++;
}
if(DBG_EXTPROG)
log_debug("args expanded to \"%s\", use %u, keep %u\n",info->command,
info->flags.use_temp_files,info->flags.keep_temp_files);
return 0;
fail:
xfree(info->command);
info->command=NULL;
return G10ERR_GENERAL;
}
/* Either handles the tempfile creation, or the fork/exec. If it
returns ok, then info->tochild is a FILE * that can be written to.
The rules are: if there are no args, then it's a fork/exec/pipe.
If there are args, but no tempfiles, then it's a fork/exec/pipe via
shell -c. If there are tempfiles, then it's a system. */
int exec_write(struct exec_info **info,const char *program,
const char *args_in,const char *name,int writeonly,int binary)
{
int ret=G10ERR_GENERAL;
if(opt.exec_disable && !opt.no_perm_warn)
{
log_info(_("external program calls are disabled due to unsafe "
"options file permissions\n"));
return ret;
}
#if defined(HAVE_GETUID) && defined(HAVE_GETEUID)
/* There should be no way to get to this spot while still carrying
setuid privs. Just in case, bomb out if we are. */
if(getuid()!=geteuid())
BUG();
#endif
if(program==NULL && args_in==NULL)
BUG();
*info=xmalloc_clear(sizeof(struct exec_info));
if(name)
(*info)->name=xstrdup(name);
(*info)->flags.binary=binary;
(*info)->flags.writeonly=writeonly;
/* Expand the args, if any */
if(args_in && expand_args(*info,args_in))
goto fail;
#ifdef EXEC_TEMPFILE_ONLY
if(!(*info)->flags.use_temp_files)
{
log_error(_("this platform requires temporary files when calling"
" external programs\n"));
goto fail;
}
#else /* !EXEC_TEMPFILE_ONLY */
/* If there are no args, or there are args, but no temp files, we
can use fork/exec/pipe */
if(args_in==NULL || (*info)->flags.use_temp_files==0)
{
int to[2],from[2];
if(pipe(to)==-1)
goto fail;
if(pipe(from)==-1)
{
close(to[0]);
close(to[1]);
goto fail;
}
if(((*info)->child=fork())==-1)
{
close(to[0]);
close(to[1]);
close(from[0]);
close(from[1]);
goto fail;
}
if((*info)->child==0)
{
char *shell=getenv("SHELL");
if(shell==NULL)
shell="/bin/sh";
/* I'm the child */
/* If the program isn't going to respond back, they get to
keep their stdout/stderr */
if(!(*info)->flags.writeonly)
{
/* implied close of STDERR */
if(dup2(STDOUT_FILENO,STDERR_FILENO)==-1)
_exit(1);
/* implied close of STDOUT */
close(from[0]);
if(dup2(from[1],STDOUT_FILENO)==-1)
_exit(1);
}
/* implied close of STDIN */
close(to[1]);
if(dup2(to[0],STDIN_FILENO)==-1)
_exit(1);
if(args_in==NULL)
{
if(DBG_EXTPROG)
log_debug("execlp: %s\n",program);
execlp(program,program,(void *)NULL);
}
else
{
if(DBG_EXTPROG)
log_debug("execlp: %s -c %s\n",shell,(*info)->command);
execlp(shell,shell,"-c",(*info)->command,(void *)NULL);
}
/* If we get this far the exec failed. Clean up and return. */
if(args_in==NULL)
log_error(_("unable to execute program `%s': %s\n"),
program,strerror(errno));
else
log_error(_("unable to execute shell `%s': %s\n"),
shell,strerror(errno));
/* This mimics the POSIX sh behavior - 127 means "not found"
from the shell. */
if(errno==ENOENT)
_exit(127);
_exit(1);
}
/* I'm the parent */
close(to[0]);
(*info)->tochild=fdopen(to[1],binary?"wb":"w");
if((*info)->tochild==NULL)
{
ret = gpg_error_from_syserror ();
close(to[1]);
goto fail;
}
close(from[1]);
(*info)->fromchild=iobuf_fdopen(from[0],"r");
if((*info)->fromchild==NULL)
{
ret = gpg_error_from_syserror ();
close(from[0]);
goto fail;
}
/* fd iobufs are cached?! */
iobuf_ioctl((*info)->fromchild,3,1,NULL);
return 0;
}
#endif /* !EXEC_TEMPFILE_ONLY */
if(DBG_EXTPROG)
log_debug("using temp file `%s'\n",(*info)->tempfile_in);
/* It's not fork/exec/pipe, so create a temp file */
if( is_secured_filename ((*info)->tempfile_in) )
{
(*info)->tochild = NULL;
errno = EPERM;
}
else
(*info)->tochild=fopen((*info)->tempfile_in,binary?"wb":"w");
if((*info)->tochild==NULL)
{
ret = gpg_error_from_syserror ();
log_error(_("can't create `%s': %s\n"),
(*info)->tempfile_in,strerror(errno));
goto fail;
}
ret=0;
fail:
return ret;
}
int exec_read(struct exec_info *info)
{
int ret=G10ERR_GENERAL;
fclose(info->tochild);
info->tochild=NULL;
if(info->flags.use_temp_files)
{
if(DBG_EXTPROG)
log_debug("system() command is %s\n",info->command);
#if defined (_WIN32)
info->progreturn=w32_system(info->command);
#else
info->progreturn=system(info->command);
#endif
if(info->progreturn==-1)
{
log_error(_("system error while calling external program: %s\n"),
strerror(errno));
info->progreturn=127;
goto fail;
}
#if defined(WIFEXITED) && defined(WEXITSTATUS)
if(WIFEXITED(info->progreturn))
info->progreturn=WEXITSTATUS(info->progreturn);
else
{
log_error(_("unnatural exit of external program\n"));
info->progreturn=127;
goto fail;
}
#else
/* If we don't have the macros, do the best we can. */
info->progreturn = (info->progreturn & 0xff00) >> 8;
#endif
/* 127 is the magic value returned from system() to indicate
that the shell could not be executed, or from /bin/sh to
indicate that the program could not be executed. */
if(info->progreturn==127)
{
log_error(_("unable to execute external program\n"));
goto fail;
}
if(!info->flags.writeonly)
{
info->fromchild=iobuf_open(info->tempfile_out);
if (info->fromchild
&& is_secured_file (iobuf_get_fd (info->fromchild)))
{
iobuf_close (info->fromchild);
info->fromchild = NULL;
errno = EPERM;
}
if(info->fromchild==NULL)
{
ret = gpg_error_from_syserror ();
log_error(_("unable to read external program response: %s\n"),
strerror(errno));
goto fail;
}
/* Do not cache this iobuf on close */
iobuf_ioctl(info->fromchild,3,1,NULL);
}
}
ret=0;
fail:
return ret;
}
int exec_finish(struct exec_info *info)
{
int ret=info->progreturn;
if(info->fromchild)
iobuf_close(info->fromchild);
if(info->tochild)
fclose(info->tochild);
#ifndef EXEC_TEMPFILE_ONLY
if(info->child>0)
{
if(waitpid(info->child,&info->progreturn,0)!=0 &&
WIFEXITED(info->progreturn))
ret=WEXITSTATUS(info->progreturn);
else
{
log_error(_("unnatural exit of external program\n"));
ret=127;
}
}
#endif
if(info->flags.madedir && !info->flags.keep_temp_files)
{
if(info->tempfile_in)
{
if(unlink(info->tempfile_in)==-1)
log_info(_("WARNING: unable to remove tempfile (%s) `%s': %s\n"),
"in",info->tempfile_in,strerror(errno));
}
if(info->tempfile_out)
{
if(unlink(info->tempfile_out)==-1)
log_info(_("WARNING: unable to remove tempfile (%s) `%s': %s\n"),
"out",info->tempfile_out,strerror(errno));
}
if(rmdir(info->tempdir)==-1)
log_info(_("WARNING: unable to remove temp directory `%s': %s\n"),
info->tempdir,strerror(errno));
}
xfree(info->command);
xfree(info->name);
xfree(info->tempdir);
xfree(info->tempfile_in);
xfree(info->tempfile_out);
xfree(info);
return ret;
}
#endif /* ! NO_EXEC */
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