1.\" $NetBSD: ssp.3,v 1.2 2007/08/20 16:07:05 perry 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.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the NetBSD 20.\" Foundation, Inc. and its contributors. 21.\" 4. Neither the name of The NetBSD Foundation nor the names of its 22.\" contributors may be used to endorse or promote products derived 23.\" from this software without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 26.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 29.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35.\" POSSIBILITY OF SUCH DAMAGE. 36.\" 37.\" 38.Dd May 23, 2007 39.Dt SSP 3 40.Os 41.Sh NAME 42.Nm ssp 43.Nd bounds checked libc functions 44.Sh LIBRARY 45.Lb libssp 46.Sh SYNOPSIS 47.In ssp/stdio.h 48.Ft int 49.Fn sprintf "char *str" "const char *fmt" "..." 50.Ft int 51.Fn vsprintf "char *str" "const char *fmt" "va_list ap" 52.Ft int 53.Fn snprintf "char *str" "size_t len" "const char *fmt" "..." 54.Ft int 55.Fn vsnprintf "char *str" "size_t len" "const char *fmt" "va_list ap" 56.Ft char * 57.Fn gets "char *str" 58.Ft char * 59.Fn fgets "char *str" "int len" "FILE *fp" 60.In ssp/string.h 61.Ft void * 62.Fn memcpy "void *str" "const void *ptr" "size_t len" 63.Ft void * 64.Fn memmove "void *str" "const void *ptr" "size_t len" 65.Ft void * 66.Fn memset "void *str" "int val" "size_t len" 67.Ft char * 68.Fn strcpy "char *str" "const char *ptr" "size_t len" 69.Ft char * 70.Fn strcat "char *str" "const char *ptr" "size_t len" 71.Ft char * 72.Fn strncpy "char *str" "const char *ptr" "size_t len" 73.Ft char * 74.Fn strncat "char *str" "const char *ptr" "size_t len" 75.In ssp/strings.h 76.Ft void * 77.Fn bcopy "const void *ptr" "void *str" "size_t len" 78.Ft void * 79.Fn bzero "void *str" "size_t len" 80.In ssp/unistd.h 81.Ft ssize_t 82.Fn read "int fd" "void *str" "size_t len" 83.Ft int 84.Fn readlink "const char * restrict path" "char * restrict str" "size_t len" 85.Ft int 86.Fn getcwd "char *str" "size_t len" 87.Sh DESCRIPTION 88When 89.Dv _FORTIFY_SOURCE 90bounds checking is enabled as described below, the above functions get 91overwriten to use the 92.Xr gcc 1 93.Xr __builtin_object_size 3 94function to compute the size of 95.Fa str 96if known at compile time and perform bounds check on it in order 97to avoid data buffer or stack buffer overflows. 98If an overflow is detected the routines will call 99.Xr abort 3 . 100.Pp 101To enable these function overrides the following should be added to the 102.Xr gcc 1 103command line: 104.Dq \-I/usr/include/ssp 105to override the standard include files and 106.Dq \-D_FORTIFY_SOURCE=1 107or 108.Dq \-D_FORTIFY_SOURCE=2 . 109.Pp 110If 111.Dv _FORTIFY_SOURCE is set to 112.Dv 1 113the code will compute the maximum possible buffer size for 114.Fa str , 115and if set to 116.Dv 2 117it will compute the minimum buffer size. 118.Sh SEE ALSO 119.Xr gcc 1 , 120.Xr read 2 , 121.Xr readlink 2 , 122.Xr getcwd 3 , 123.Xr stdio 3 , 124.Xr string 3 , 125.Xr abort 3 , 126.Xr __builtin_object_size 3 127.Sh HISTORY 128The 129.Nm ssp 130library appeared 131.Nx 4.0 . 132