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8b0682644e
We haven't exposed gets(3) in a long time, rip out __gets_chk before it's too late and something builds a gets(3) user with it enabled.
129 lines
3.8 KiB
Groff
129 lines
3.8 KiB
Groff
.\" $NetBSD: ssp.3,v 1.9 2015/12/03 13:11:45 christos Exp $
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.\"
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.\" SPDX-License-Identifier: BSD-2-Clause
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.\"
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.\" Copyright (c) 2007 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Christos Zoulas.
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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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\"
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.Dd December 3, 2015
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.Dt SSP 3
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.Os
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.Sh NAME
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.Nm ssp
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.Nd bounds checked libc functions
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.Sh LIBRARY
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.Lb libssp
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.Sh SYNOPSIS
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.In ssp/stdio.h
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.Ft int
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.Fn sprintf "char *str" "const char *fmt" "..."
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.Ft int
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.Fn vsprintf "char *str" "const char *fmt" "va_list ap"
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.Ft int
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.Fn snprintf "char *str" "size_t len" "const char *fmt" "..."
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.Ft int
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.Fn vsnprintf "char *str" "size_t len" "const char *fmt" "va_list ap"
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.Ft char *
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.Fn fgets "char *str" "int len" "FILE *fp"
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.In ssp/string.h
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.Ft void *
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.Fn memcpy "void *str" "const void *ptr" "size_t len"
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.Ft void *
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.Fn memmove "void *str" "const void *ptr" "size_t len"
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.Ft void *
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.Fn memset "void *str" "int val" "size_t len"
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.Ft char *
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.Fn stpcpy "char *str" "const char *ptr"
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.Ft char *
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.Fn strcpy "char *str" "const char *ptr"
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.Ft char *
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.Fn strcat "char *str" "const char *ptr"
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.Ft char *
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.Fn strncpy "char *str" "const char *ptr" "size_t len"
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.Ft char *
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.Fn strncat "char *str" "const char *ptr" "size_t len"
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.In ssp/strings.h
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.Ft void *
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.Fn bcopy "const void *ptr" "void *str" "size_t len"
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.Ft void *
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.Fn bzero "void *str" "size_t len"
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.In ssp/unistd.h
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.Ft ssize_t
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.Fn read "int fd" "void *str" "size_t len"
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.Ft int
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.Fn readlink "const char * restrict path" "char * restrict str" "size_t len"
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.Ft int
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.Fn getcwd "char *str" "size_t len"
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.Sh DESCRIPTION
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When
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.Dv _FORTIFY_SOURCE
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bounds checking is enabled as described below, the above functions get
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overwritten to use the
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.Xr __builtin_object_size 3
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function to compute the size of
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.Fa str ,
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if known at compile time,
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and perform bounds check on it in order
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to avoid data buffer or stack buffer overflows.
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If an overflow is detected, the routines will call
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.Xr abort 3 .
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.Pp
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To enable these function overrides the following should be added to the
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.Xr clang 1
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or
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.Xr gcc 1
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command line:
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.Dq \-D_FORTIFY_SOURCE=1
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or
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.Dq \-D_FORTIFY_SOURCE=2 .
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.Pp
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If
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.Dv _FORTIFY_SOURCE is set to
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.Dv 1
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the code will compute the maximum possible buffer size for
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.Fa str ,
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and if set to
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.Dv 2
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it will compute the minimum buffer size.
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.Sh SEE ALSO
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.Xr clang 1 ,
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.Xr gcc 1 ,
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.Xr __builtin_object_size 3 ,
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.Xr stdio 3 ,
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.Xr string 3 ,
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.Xr security 7
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.Sh HISTORY
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The
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.Nm
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library appeared in
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.Nx 4.0 .
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This version of the
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.Nm
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library replaced the GNU library of the same name in
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.Fx 12.2 .
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