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* Askpass-FIFO - Read a password from a FIFO and output it
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* Copyright © 2008-2011 Teddy Hogeborn
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* Copyright © 2008-2011 Björn Påhlsson
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* Copyright © 2008-2016 Teddy Hogeborn
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* Copyright © 2008-2016 Björn Påhlsson
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* This program is free software: you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* along with this program. If not, see
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* <http://www.gnu.org/licenses/>.
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* Contact the authors at <mandos@fukt.bsnet.se>.
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* Contact the authors at <mandos@recompile.se>.
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#define _GNU_SOURCE /* TEMP_FAILURE_RETRY() */
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#include <sys/types.h> /* ssize_t */
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#include <sys/types.h> /* uid_t, gid_t, ssize_t */
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#include <sys/stat.h> /* mkfifo(), S_IRUSR, S_IWUSR */
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#include <iso646.h> /* and */
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#include <errno.h> /* errno, EACCES, ENOTDIR, ELOOP,
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ENFILE, ENOMEM, EBADF, EINVAL, EIO,
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#include <error.h> /* error() */
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#include <stdio.h> /* fprintf(), vfprintf(),
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#include <stdlib.h> /* EXIT_FAILURE, NULL, size_t, free(),
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realloc(), EXIT_SUCCESS */
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#include <fcntl.h> /* open(), O_RDONLY */
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#include <sysexits.h> /* EX_OSERR, EX_OSFILE,
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EX_UNAVAILABLE, EX_IOERR */
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#include <string.h> /* strerror() */
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#include <stdarg.h> /* va_list, va_start(), ... */
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/* Function to use when printing errors */
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__attribute__((format (gnu_printf, 3, 4)))
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void error_plus(int status, int errnum, const char *formatstring,
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va_start(ap, formatstring);
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ret = vasprintf(&text, formatstring, ap);
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fprintf(stderr, "Mandos plugin %s: ",
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program_invocation_short_name);
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vfprintf(stderr, formatstring, ap);
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fprintf(stderr, ": ");
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fprintf(stderr, "%s\n", strerror(errnum));
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error(status, errno, "vasprintf while printing error");
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fprintf(stderr, "Mandos plugin ");
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error(status, errnum, "%s", text);
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int main(__attribute__((unused))int argc,
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__attribute__((unused))char **argv){
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const char passfifo[] = "/lib/cryptsetup/passfifo";
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ret = mkfifo(passfifo, S_IRUSR | S_IWUSR);
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error(0, errno, "mkfifo");
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error_plus(EX_OSFILE, errno, "mkfifo");
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error_plus(EX_OSERR, errno, "mkfifo");
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return EX_UNAVAILABLE; /* no "/lib/cryptsetup"? */
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/* no "/lib/cryptsetup"? */
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error_plus(EX_UNAVAILABLE, errno, "mkfifo");
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break; /* not an error */
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/* Lower group privileges */
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if(setgid(gid) == -1){
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error_plus(0, errno, "setgid");
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/* Lower user privileges */
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if(setuid(uid) == -1){
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error_plus(0, errno, "setuid");
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/* Read from FIFO */
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size_t buf_len = 0;
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if(buf_len + blocksize > buf_allocated){
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char *tmp = realloc(buf, buf_allocated + blocksize);
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error(0, errno, "realloc");
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error_plus(0, errno, "realloc");