192 lines
5.2 KiB
Groff
192 lines
5.2 KiB
Groff
.\" $OpenBSD: readpassphrase.3,v 1.7 2001/12/15 15:37:51 millert Exp $
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.\"
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.\" Copyright (c) 2000 Todd C. Miller <Todd.Miller@courtesan.com>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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.\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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.\" AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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.\" THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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.\" EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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.\" PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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.\" OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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.\" OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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.\" ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 7, 2001
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.Dt READPASSPHRASE 3
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.Os
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.Sh NAME
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.Nm readpassphrase
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.Nd get a passphrase from the user
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.Sh SYNOPSIS
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.In readpassphrase.h
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.Ft "char *"
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.Fn readpassphrase "const char *prompt" "char *buf" "size_t bufsiz" "int flags"
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.Sh DESCRIPTION
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The
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.Fn readpassphrase
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function displays a prompt to, and reads in a passphrase from,
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.Pa /dev/tty .
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If this file is inaccessible
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and the
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.Dv RPP_REQUIRE_TTY
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flag is not set,
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.Fn readpassphrase
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displays the prompt on the standard error output and reads from the standard
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input.
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In this case it is generally not possible to turn off echo.
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.Pp
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Up to
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.Fa bufsiz
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\- 1 characters (one is for the
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.Dv NUL )
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are read into the provided buffer
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.Fa buf .
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Any additional
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characters and the terminating newline (or return) character are discarded.
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.Pp
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The
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.Fn readpassphrase
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function
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takes the following optional
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.Fa flags :
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.Pp
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.Bl -tag -width ".Dv RPP_REQUIRE_TTY" -compact
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.It Dv RPP_ECHO_OFF
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turn off echo (default behavior)
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.It Dv RPP_ECHO_ON
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leave echo on
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.It Dv RPP_REQUIRE_TTY
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fail if there is no tty
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.It Dv RPP_FORCELOWER
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force input to lower case
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.It Dv RPP_FORCEUPPER
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force input to upper case
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.It Dv RPP_SEVENBIT
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strip the high bit from input
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.El
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.Pp
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The calling process should zero the passphrase as soon as possible to
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avoid leaving the cleartext passphrase visible in the process's address
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space.
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.Sh RETURN VALUES
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Upon successful completion,
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.Fn readpassphrase
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returns a pointer to the null-terminated passphrase.
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If an error is encountered, the terminal state is restored and
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a
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.Dv NULL
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pointer is returned.
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.Sh FILES
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.Bl -tag -width ".Pa /dev/tty" -compact
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.It Pa /dev/tty
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.El
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.Sh EXAMPLES
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The following code fragment will read a passphrase from
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.Pa /dev/tty
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into the buffer
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.Fa passbuf .
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.Bd -literal -offset indent
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char passbuf[1024];
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\&...
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if (readpassphrase("Response: ", passbuf, sizeof(passbuf),
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RPP_REQUIRE_TTY) == NULL)
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errx(1, "unable to read passphrase");
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if (compare(transform(passbuf), epass) != 0)
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errx(1, "bad passphrase");
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\&...
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memset(passbuf, 0, sizeof(passbuf));
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.Ed
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.Sh SIGNALS
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The
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.Fn readpassphrase
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function
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will catch the following signals:
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.Pp
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.Bl -tag -compact
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.It Dv SIGINT
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.It Dv SIGHUP
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.It Dv SIGQUIT
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.It Dv SIGTERM
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.It Dv SIGTSTP
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.It Dv SIGTTIN
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.It Dv SIGTTOU
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.El
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.Pp
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When one of the above signals is intercepted, terminal echo will
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be restored if it had previously been turned off.
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If a signal handler was installed for the signal when
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.Fn readpassphrase
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was called that handler is then executed.
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If no handler was previously installed for the signal then the
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default action is taken as per
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.Xr sigaction 2 .
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.Pp
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The
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.Dv SIGTSTP , SIGTTIN ,
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and
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.Dv SIGTTOU
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signals (stop signal generated from keyboard or due to terminal I/O
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from a background process) are treated specially.
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When the process is resumed after it has been stopped,
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.Fn readpassphrase
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will reprint the prompt and the user may then enter a passphrase.
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.Sh ERRORS
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.Bl -tag -width Er
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.It Bq Er EINTR
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The
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.Fn readpassphrase
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function was interrupted by a signal.
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.It Bq Er EINVAL
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The
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.Fa bufsiz
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argument was zero.
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.It Bq Er EIO
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The process is a member of a background process attempting to read
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from its controlling terminal, the process is ignoring or blocking
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the
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.Dv SIGTTIN
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signal or the process group is orphaned.
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.It Bq Er EMFILE
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The process has already reached its limit for open file descriptors.
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.It Bq Er ENFILE
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The system file table is full.
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.It Bq Er ENOTTY
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There is no controlling terminal and the
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.Dv RPP_REQUIRE_TTY
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flag was specified.
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.El
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.Sh SEE ALSO
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.Xr sigaction 2 ,
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.Xr getpass 3
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.Sh STANDARDS
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The
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.Fn readpassphrase
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function is an
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extension and should not be used if portability is desired.
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.Sh HISTORY
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The
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.Fn readpassphrase
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function first appeared in
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.Ox 2.9 .
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