freebsd-skq/libexec/rtld-elf/rtld_printf.h

/*-
 * Copyright 2011 Konstantin Belousov <kib@FreeBSD.org>.
 * All rights reserved.
 *
 * 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 ``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 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.
 *
 * $FreeBSD$
 */

#ifndef RTLD_PRINTF_H
#define RTLD_PRINTF_H 1

#include <sys/cdefs.h>
#include <unistd.h>

int rtld_snprintf(char *buf, size_t bufsize, const char *fmt, ...)
    __printflike(3, 4);
int rtld_vsnprintf(char *buf, size_t bufsize, const char *fmt, va_list ap);
int rtld_vfdprintf(int fd, const char *fmt, va_list ap);
int rtld_fdprintf(int fd, const char *fmt, ...) __printflike(2, 3);
void rtld_fdputstr(int fd, const char *str);
void rtld_fdputchar(int fd, int c);

#define	rtld_printf(...) rtld_fdprintf(STDOUT_FILENO, __VA_ARGS__)
#define	rtld_putstr(str) rtld_fdputstr(STDOUT_FILENO, (str))
#define	rtld_putchar(c) rtld_fdputchar(STDOUT_FILENO, (c))

#endif
Rtld links with the specially built pic static libc library to get some C runtime services, like printf(). Unfortunately, the multithread-safeness measures in the libc do not work in rtld environment. Rip the kernel printf() implementation and use it in the rtld instead of libc version. This printf does not require any shared global data and thus is mt-safe. Systematically use rtld_printf() and related functions, remove the calls to err(3). Note that stdio is still pulled from libc due to libmap implementaion using fopen(). This is safe but unoptimal, and can be changed later. Reported and tested by: pgj Diagnosed and reviewed by: kan (previous version) Approved by: re (bz) 2011-08-24 20:05:13 +00:00			`/*-`
			`* Copyright 2011 Konstantin Belousov <kib@FreeBSD.org>.`
			`* All rights reserved.`
			`*`
			`* 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 ``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 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.`
			`*`
			`* $FreeBSD$`
			`*/`

			`#ifndef RTLD_PRINTF_H`
			`#define RTLD_PRINTF_H 1`

			`#include <sys/cdefs.h>`
			`#include <unistd.h>`

Add the LD_LIBRARY_PATH_FDS environmental variable. This variable allows the loading of shared libraries via directory descriptors rather than via library paths. If LD_LIBRARY_PATH_FDS=3:4:12, the directories represented by file descriptors 3, 4 and 12 will searched for shared libraries before the normal path-based mechanisms are used. This allows us to execute unprivileged binaries from within a Capsicum sandbox even if they require shared libraries. Approved by: rwatson (mentor) Reviewed by: kib MFC after: 3 weeks Sponsored by: DARPA/AFRL 2014-06-20 17:08:32 +00:00			`int rtld_snprintf(char buf, size_t bufsize, const char fmt, ...)`
			`__printflike(3, 4);`
Rtld links with the specially built pic static libc library to get some C runtime services, like printf(). Unfortunately, the multithread-safeness measures in the libc do not work in rtld environment. Rip the kernel printf() implementation and use it in the rtld instead of libc version. This printf does not require any shared global data and thus is mt-safe. Systematically use rtld_printf() and related functions, remove the calls to err(3). Note that stdio is still pulled from libc due to libmap implementaion using fopen(). This is safe but unoptimal, and can be changed later. Reported and tested by: pgj Diagnosed and reviewed by: kan (previous version) Approved by: re (bz) 2011-08-24 20:05:13 +00:00			`int rtld_vsnprintf(char buf, size_t bufsize, const char fmt, va_list ap);`
			`int rtld_vfdprintf(int fd, const char *fmt, va_list ap);`
			`int rtld_fdprintf(int fd, const char *fmt, ...) __printflike(2, 3);`
			`void rtld_fdputstr(int fd, const char *str);`
			`void rtld_fdputchar(int fd, int c);`

			`#define rtld_printf(...) rtld_fdprintf(STDOUT_FILENO, __VA_ARGS__)`
			`#define rtld_putstr(str) rtld_fdputstr(STDOUT_FILENO, (str))`
			`#define rtld_putchar(c) rtld_fdputchar(STDOUT_FILENO, (c))`

			`#endif`