1.\" $NetBSD: ssp.3,v 1.8 2013/11/07 02:01:42 christos Exp $ 2.\" 3.\" Copyright (c) 2007 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Christos Zoulas. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.\" 31.Dd November 6, 2013 32.Dt SSP 3 33.Os 34.Sh NAME 35.Nm ssp 36.Nd bounds checked libc functions 37.Sh LIBRARY 38.Lb libssp 39.Sh SYNOPSIS 40.In ssp/stdio.h 41.Ft int 42.Fn sprintf "char *str" "const char *fmt" "..." 43.Ft int 44.Fn vsprintf "char *str" "const char *fmt" "va_list ap" 45.Ft int 46.Fn snprintf "char *str" "size_t len" "const char *fmt" "..." 47.Ft int 48.Fn vsnprintf "char *str" "size_t len" "const char *fmt" "va_list ap" 49.Ft char * 50.Fn gets "char *str" 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 gcc 1 98command line: 99.Dq \-I/usr/include/ssp 100to override the standard include files and 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 gcc 1 , 115.Xr __builtin_object_size 3 , 116.Xr stdio 3 , 117.Xr string 3 , 118.Xr security 7 119.Sh HISTORY 120The 121.Nm ssp 122library appeared 123.Nx 4.0 . 124