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/* -*- coding: utf-8 -*- */
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* Askpass-FIFO - Read a password from a FIFO and output it
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* Copyright © 2008-2019, 2021 Teddy Hogeborn
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* Copyright © 2008-2019, 2021 Björn Påhlsson
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* This file is part of Mandos.
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* Mandos is free software: you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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* Mandos is distributed in the hope that it will be useful, but
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* Passprompt - Read a password from a FIFO and output it
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* Copyright © 2008,2009 Teddy Hogeborn
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* Copyright © 2008,2009 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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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with Mandos. If not, see <http://www.gnu.org/licenses/>.
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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@recompile.se>.
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* Contact the authors at <https://www.fukt.bsnet.se/~belorn/> and
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* <https://www.fukt.bsnet.se/~teddy/>.
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#define _GNU_SOURCE /* vasprintf(),
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program_invocation_short_name */
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#include <sys/types.h> /* uid_t, gid_t, getuid(), getgid(),
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#include <unistd.h> /* uid_t, gid_t, ssize_t, getuid(),
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getgid(), setgid(), setuid(),
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read(), close(), write(),
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#include <stdarg.h> /* va_list, va_start(), vfprintf() */
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#include <stdio.h> /* vasprintf(), fprintf(), stderr,
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#include <errno.h> /* program_invocation_short_name,
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errno, EACCES, ENOTDIR, ELOOP,
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ENAMETOOLONG, ENOSPC, EROFS,
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ENOENT, EEXIST, EFAULT, EMFILE,
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ENFILE, ENOMEM, EBADF, EINVAL, EIO,
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#include <string.h> /* strerror() */
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#include <error.h> /* error() */
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#include <stdlib.h> /* free(), realloc(), EXIT_SUCCESS */
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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/stat.h> /* mkfifo(), S_IRUSR, S_IWUSR */
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#include <sysexits.h> /* EX_OSFILE, EX_OSERR,
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EX_UNAVAILABLE, EX_IOERR */
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#include <iso646.h> /* and */
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#include <errno.h> /* errno, EEXIST */
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#include <stdio.h> /* perror() */
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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 <stddef.h> /* NULL, size_t */
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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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__builtin_unreachable();
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fprintf(stderr, "Mandos plugin ");
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error(status, errnum, "%s", text);
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__builtin_unreachable();
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#include <unistd.h> /* read(), close(), write(),
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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_plus(EX_OSFILE, errno, "mkfifo");
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__builtin_unreachable();
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error_plus(EX_OSERR, errno, "mkfifo");
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__builtin_unreachable();
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/* no "/lib/cryptsetup"? */
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error_plus(EX_UNAVAILABLE, errno, "mkfifo");
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__builtin_unreachable();
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break; /* not an error */
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ret = TEMP_FAILURE_RETRY(mkfifo(passfifo, S_IRUSR | S_IWUSR));
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if(ret == -1 and errno != EEXIST){
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int fifo_fd = open(passfifo, O_RDONLY);
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int fifo_fd = TEMP_FAILURE_RETRY(open(passfifo, O_RDONLY));
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if(fifo_fd == -1){
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error_plus(0, errno, "open");
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return EX_UNAVAILABLE;
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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_allocated = 0;
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const size_t blocksize = 1024;
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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_plus(0, errno, "realloc");
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buf_allocated += blocksize;
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sret = read(fifo_fd, buf + buf_len, buf_allocated - buf_len);
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sret = TEMP_FAILURE_RETRY(read(fifo_fd, buf + buf_len,
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buf_allocated - buf_len));
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error_plus(0, errno, "read");
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return EX_UNAVAILABLE;
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buf_len += (size_t)sret;
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TEMP_FAILURE_RETRY(close(fifo_fd));
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/* Print password to stdout */
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size_t written = 0;
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while(written < buf_len){
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sret = write(STDOUT_FILENO, buf + written, buf_len - written);
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sret = TEMP_FAILURE_RETRY(write(STDOUT_FILENO, buf + written,
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error_plus(0, errno, "write");
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written += (size_t)sret;
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ret = close(STDOUT_FILENO);
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error_plus(0, errno, "close");
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return EXIT_SUCCESS;
added
removed
plugins.d/askpass-fifo.c
