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 gets "char *str" 53.Ft char * 54.Fn fgets "char *str" "int len" "FILE *fp" 55.In ssp/string.h 56.Ft void * 57.Fn memcpy "void *str" "const void *ptr" "size_t len" 58.Ft void * 59.Fn memmove "void *str" "const void *ptr" "size_t len" 60.Ft void * 61.Fn memset "void *str" "int val" "size_t len" 62.Ft char * 63.Fn stpcpy "char *str" "const char *ptr" 64.Ft char * 65.Fn strcpy "char *str" "const char *ptr" 66.Ft char * 67.Fn strcat "char *str" "const char *ptr" 68.Ft char * 69.Fn strncpy "char *str" "const char *ptr" "size_t len" 70.Ft char * 71.Fn strncat "char *str" "const char *ptr" "size_t len" 72.In ssp/strings.h 73.Ft void * 74.Fn bcopy "const void *ptr" "void *str" "size_t len" 75.Ft void * 76.Fn bzero "void *str" "size_t len" 77.In ssp/unistd.h 78.Ft ssize_t 79.Fn read "int fd" "void *str" "size_t len" 80.Ft int 81.Fn readlink "const char * restrict path" "char * restrict str" "size_t len" 82.Ft int 83.Fn getcwd "char *str" "size_t len" 84.Sh DESCRIPTION 85When 86.Dv _FORTIFY_SOURCE 87bounds checking is enabled as described below, the above functions get 88overwritten to use the 89.Xr __builtin_object_size 3 90function to compute the size of 91.Fa str , 92if known at compile time, 93and perform bounds check on it in order 94to avoid data buffer or stack buffer overflows. 95If an overflow is detected, the routines will call 96.Xr abort 3 . 97.Pp 98To enable these function overrides the following should be added to the 99.Xr clang 1 100or 101.Xr gcc 1 102command line: 103.Dq \-D_FORTIFY_SOURCE=1 104or 105.Dq \-D_FORTIFY_SOURCE=2 . 106.Pp 107If 108.Dv _FORTIFY_SOURCE is set to 109.Dv 1 110the code will compute the maximum possible buffer size for 111.Fa str , 112and if set to 113.Dv 2 114it will compute the minimum buffer size. 115.Sh SEE ALSO 116.Xr clang 1 , 117.Xr gcc 1 , 118.Xr __builtin_object_size 3 , 119.Xr stdio 3 , 120.Xr string 3 , 121.Xr security 7 122.Sh HISTORY 123The 124.Nm 125library appeared in 126.Nx 4.0 . 127This version of the 128.Nm 129library replaced the GNU library of the same name in 130.Fx 12.2 . 131