1.\" $NetBSD: ssp.3,v 1.9 2015/12/03 13:11:45 christos Exp $ 2.\" 3.\" SPDX-License-Identifier: BSD-2-Clause 4.\" 5.\" Copyright (c) 2007 The NetBSD Foundation, Inc. 6.\" All rights reserved. 7.\" 8.\" This code is derived from software contributed to The NetBSD Foundation 9.\" by Christos Zoulas. 10.\" 11.\" Redistribution and use in source and binary forms, with or without 12.\" modification, are permitted provided that the following conditions 13.\" are met: 14.\" 1. Redistributions of source code must retain the above copyright 15.\" notice, this list of conditions and the following disclaimer. 16.\" 2. Redistributions in binary form must reproduce the above copyright 17.\" notice, this list of conditions and the following disclaimer in the 18.\" documentation and/or other materials provided with the distribution. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 21.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 24.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30.\" POSSIBILITY OF SUCH DAMAGE. 31.\" 32.\" 33.Dd December 3, 2015 34.Dt SSP 3 35.Os 36.Sh NAME 37.Nm ssp 38.Nd bounds checked libc functions 39.Sh LIBRARY 40.Lb libssp 41.Sh SYNOPSIS 42.In ssp/stdio.h 43.Ft int 44.Fn sprintf "char *str" "const char *fmt" "..." 45.Ft int 46.Fn vsprintf "char *str" "const char *fmt" "va_list ap" 47.Ft int 48.Fn snprintf "char *str" "size_t len" "const char *fmt" "..." 49.Ft int 50.Fn vsnprintf "char *str" "size_t len" "const char *fmt" "va_list ap" 51.Ft char * 52.Fn fgets "char *str" "int len" "FILE *fp" 53.In ssp/string.h 54.Ft void * 55.Fn memcpy "void *str" "const void *ptr" "size_t len" 56.Ft void * 57.Fn memmove "void *str" "const void *ptr" "size_t len" 58.Ft void * 59.Fn memset "void *str" "int val" "size_t len" 60.Ft char * 61.Fn stpcpy "char *str" "const char *ptr" 62.Ft char * 63.Fn strcpy "char *str" "const char *ptr" 64.Ft char * 65.Fn strcat "char *str" "const char *ptr" 66.Ft char * 67.Fn strncpy "char *str" "const char *ptr" "size_t len" 68.Ft char * 69.Fn strncat "char *str" "const char *ptr" "size_t len" 70.In ssp/strings.h 71.Ft void * 72.Fn bcopy "const void *ptr" "void *str" "size_t len" 73.Ft void * 74.Fn bzero "void *str" "size_t len" 75.In ssp/unistd.h 76.Ft ssize_t 77.Fn read "int fd" "void *str" "size_t len" 78.Ft int 79.Fn readlink "const char * restrict path" "char * restrict str" "size_t len" 80.Ft int 81.Fn getcwd "char *str" "size_t len" 82.Sh DESCRIPTION 83When 84.Dv _FORTIFY_SOURCE 85bounds checking is enabled as described below, the above functions get 86overwritten to use the 87.Xr __builtin_object_size 3 88function to compute the size of 89.Fa str , 90if known at compile time, 91and perform bounds check on it in order 92to avoid data buffer or stack buffer overflows. 93If an overflow is detected, the routines will call 94.Xr abort 3 . 95.Pp 96To enable these function overrides the following should be added to the 97.Xr clang 1 98or 99.Xr gcc 1 100command line: 101.Dq \-D_FORTIFY_SOURCE=1 102or 103.Dq \-D_FORTIFY_SOURCE=2 . 104.Pp 105If 106.Dv _FORTIFY_SOURCE is set to 107.Dv 1 108the code will compute the maximum possible buffer size for 109.Fa str , 110and if set to 111.Dv 2 112it will compute the minimum buffer size. 113.Sh SEE ALSO 114.Xr clang 1 , 115.Xr gcc 1 , 116.Xr __builtin_object_size 3 , 117.Xr stdio 3 , 118.Xr string 3 , 119.Xr security 7 120.Sh HISTORY 121The 122.Nm 123library appeared in 124.Nx 4.0 . 125This version of the 126.Nm 127library replaced the GNU library of the same name in 128.Fx 12.2 . 129