From 30d21d279537e46629a697908d2d207c06bc310e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Stefan=20E=C3=9Fer?= Date: Wed, 18 Nov 2020 19:44:30 +0000 Subject: [PATCH] Add function getlocalbase() to libutil. This function returns the path to the local software base directory, by default "/usr/local" (or the value of _PATH_LOCALBASE in include/paths.h when building the world). The value returned can be overridden by 2 methods: - the LOCALBASE environment variable (ignored by SUID programs) - else a non-default user.localbase sysctl value Reviewed by: hps (earlier version) Relnotes: yes Differential Revision: https://reviews.freebsd.org/D27236 --- lib/libutil/Makefile | 5 +- lib/libutil/getlocalbase.3 | 99 ++++++++++++++++++++++++++++++++++++++ lib/libutil/getlocalbase.c | 74 ++++++++++++++++++++++++++++ lib/libutil/libutil.h | 2 + 4 files changed, 178 insertions(+), 2 deletions(-) create mode 100644 lib/libutil/getlocalbase.3 create mode 100644 lib/libutil/getlocalbase.c diff --git a/lib/libutil/Makefile b/lib/libutil/Makefile index 5ea2addd5d34..df3fb622b374 100644 --- a/lib/libutil/Makefile +++ b/lib/libutil/Makefile @@ -12,7 +12,8 @@ PACKAGE= runtime LIB= util SHLIB_MAJOR= 9 -SRCS= _secure_path.c auth.c expand_number.c flopen.c fparseln.c gr_util.c \ +SRCS= _secure_path.c auth.c expand_number.c flopen.c fparseln.c \ + getlocalbase.c gr_util.c \ hexdump.c humanize_number.c kinfo_getfile.c \ kinfo_getallproc.c kinfo_getproc.c kinfo_getvmmap.c \ kinfo_getvmobject.c kld.c \ @@ -30,7 +31,7 @@ CFLAGS+= -DINET6 CFLAGS+= -I${.CURDIR} -I${SRCTOP}/lib/libc/gen/ -MAN+= expand_number.3 flopen.3 fparseln.3 hexdump.3 \ +MAN+= expand_number.3 flopen.3 fparseln.3 getlocalbase.3 hexdump.3 \ humanize_number.3 kinfo_getallproc.3 kinfo_getfile.3 \ kinfo_getproc.3 kinfo_getvmmap.3 kinfo_getvmobject.3 kld.3 \ login_auth.3 login_cap.3 \ diff --git a/lib/libutil/getlocalbase.3 b/lib/libutil/getlocalbase.3 new file mode 100644 index 000000000000..ed0a4a3c1226 --- /dev/null +++ b/lib/libutil/getlocalbase.3 @@ -0,0 +1,99 @@ +.\" +.\" SPDX-License-Identifier: BSD-2-Clause-FreeBSD +.\" +.\" Copyright 2020 Scott Long +.\" Copyright 2020 Stefan Eßer +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" $FreeBSD$ +.\" +.Dd November 18, 2020 +.Dt GETLOCALBASE 3 +.Os +.Sh NAME +.Nm getlocalbase +.Nd "return the path to the local software directory" +.Sh LIBRARY +.Lb libutil +.Sh SYNOPSIS +.In libutil.h +.Ft const char* +.Fn getlocalbase "void" +.Sh DESCRIPTION +The +.Fn getlocalbase +function returns the path to the local software base directory. +Normally this is the +.Pa /usr/local +directory. +First the +.Ev LOCALBASE +environment variable is checked. +If that does not exist then the +.Va user.localbase +sysctl is checked. +If that also does not exist then the value of the +.Dv _PATH_LOCALBASE +compile-time variable is used. +If that is undefined then the default of +.Pa /usr/local +is used. +.Pp +The value returned by the +.Fn getlocalbase +function shall not be modified. +.Sh IMPLEMENTATION NOTES +Calls to +.Fn getlocalbase +will perform a setugid check on the running binary before checking the +environment. +.Sh RETURN VALUES +The +.Fn getlocalbase +function always succeeds and returns a pointer to a string, whose length +may exceed MAXPATHLEN if it has been derived from the environment variable +LOCALBASE. +No length checks are performed on the result. +.Sh ENVIRONMENT +The +.Fn getlocalbase +library function retrieves the +.Ev LOCALBASE +environment variable. +.Sh ERRORS +The +.Fn getlocalbase +function always succeeds. +.Sh SEE ALSO +.Xr env 1 , +.Xr src.conf 5 , +.Xr sysctl 8 +.Sh HISTORY +The +.Nm +library function first appeared in +.Fx 13.0 . +.Sh AUTHORS +This +manual page was written by +.An Scott Long Aq Mt scottl@FreeBSD.org and Stefan Eßer Aq Mt se@FreeBSD.org . diff --git a/lib/libutil/getlocalbase.c b/lib/libutil/getlocalbase.c new file mode 100644 index 000000000000..3d6bcc067391 --- /dev/null +++ b/lib/libutil/getlocalbase.c @@ -0,0 +1,74 @@ +/*- + * SPDX-License-Identifier: BSD-2-Clause + * + * Copyright 2020 Stefan Eßer + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include +__FBSDID("$FreeBSD$"); + +#include +#include +#include +#include +#include +#include +#include + +#ifndef _PATH_LOCALBASE +#define _PATH_LOCALBASE "/usr/local" +#endif + +const char * +getlocalbase(void) +{ + static const int localbase_oid[2] = {CTL_USER, USER_LOCALBASE}; + char *tmppath; + size_t tmplen; + static const char *localbase = NULL; + + if (issetugid() == 0) { + tmppath = getenv("LOCALBASE"); + if (tmppath != NULL && tmppath[0] != '\0') + return (tmppath); + } + if (sysctl(localbase_oid, 2, NULL, &tmplen, NULL, 0) == 0 && + (tmppath = malloc(tmplen)) != NULL && + sysctl(localbase_oid, 2, tmppath, &tmplen, NULL, 0) == 0) { + /* + * Check for some other thread already having + * set localbase - this should use atomic ops. + * The amount of memory allocated above may leak, + * if a parallel update in another thread is not + * detected and the non-NULL pointer is overwritten. + */ + if (tmppath[0] != '\0' && + (volatile const char*)localbase == NULL) + localbase = tmppath; + else + free((void*)tmppath); + return (localbase); + } + return (_PATH_LOCALBASE); +} diff --git a/lib/libutil/libutil.h b/lib/libutil/libutil.h index 2ac5e975a2d7..bb96b2caa502 100644 --- a/lib/libutil/libutil.h +++ b/lib/libutil/libutil.h @@ -98,6 +98,8 @@ int flopen(const char *_path, int _flags, ...); int flopenat(int _dirfd, const char *_path, int _flags, ...); int forkpty(int *_amaster, char *_name, struct termios *_termp, struct winsize *_winp); +const char * + getlocalbase(void); void hexdump(const void *_ptr, int _length, const char *_hdr, int _flags); int humanize_number(char *_buf, size_t _len, int64_t _number, const char *_suffix, int _scale, int _flags);