freebsd-skq/lib/libc/gen/elf_utils.c
kib 9638d3e2e6 Fix initial exec TLS mode for dynamically loaded shared objects.
If dso uses initial exec TLS mode, rtld tries to allocate TLS in
static space. If there is no space left, the dlopen(3) fails. If space
if allocated, initial content from PT_TLS segment is distributed to
all threads' pcbs, which was missed and caused un-initialized TLS
segment for such dso after dlopen(3).

The mode is auto-detected either due to the relocation used, or if the
DF_STATIC_TLS dynamic flag is set.  In the later case, the TLS segment
is tried to allocate earlier, which increases chance of the dlopen(3)
to succeed.  LLD was recently fixed to properly emit the flag, ld.bdf
did it always.

Initial test by:	dumbbell
Tested by:	emaste (amd64), ian (arm)
Tested by:	Gerald Aryeetey <aryeeteygerald_rogers.com> (arm64)
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Differential revision:	https://reviews.freebsd.org/D19072
2019-03-29 17:52:57 +00:00

124 lines
3.7 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2010 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. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* 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.
*
* $FreeBSD$
*/
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/resource.h>
#include <sys/sysctl.h>
#include <link.h>
#include <stddef.h>
#include <string.h>
#include "libc_private.h"
#include "static_tls.h"
int __elf_phdr_match_addr(struct dl_phdr_info *, void *);
void __pthread_map_stacks_exec(void);
void __pthread_distribute_static_tls(size_t, void *, size_t, size_t);
int
__elf_phdr_match_addr(struct dl_phdr_info *phdr_info, void *addr)
{
const Elf_Phdr *ph;
int i;
for (i = 0; i < phdr_info->dlpi_phnum; i++) {
ph = &phdr_info->dlpi_phdr[i];
if (ph->p_type != PT_LOAD)
continue;
/* ELFv1 ABI for powerpc64 passes function descriptor
* pointers around, not function pointers. The function
* descriptors live in .opd, which is a non-executable segment.
* The PF_X check would therefore make all address checks fail,
* causing a crash in some instances. Don't skip over
* non-executable segments in the ELFv1 powerpc64 case.
*/
#if !defined(__powerpc64__) || (defined(_CALL_ELF) && _CALL_ELF == 2)
if ((ph->p_flags & PF_X) == 0)
continue;
#endif
if (phdr_info->dlpi_addr + ph->p_vaddr <= (uintptr_t)addr &&
(uintptr_t)addr + sizeof(addr) < phdr_info->dlpi_addr +
ph->p_vaddr + ph->p_memsz)
break;
}
return (i != phdr_info->dlpi_phnum);
}
void
__libc_map_stacks_exec(void)
{
int mib[2];
struct rlimit rlim;
u_long usrstack;
size_t len;
mib[0] = CTL_KERN;
mib[1] = KERN_USRSTACK;
len = sizeof(usrstack);
if (sysctl(mib, sizeof(mib) / sizeof(mib[0]), &usrstack, &len, NULL, 0)
== -1)
return;
if (getrlimit(RLIMIT_STACK, &rlim) == -1)
return;
mprotect((void *)(uintptr_t)(usrstack - rlim.rlim_cur),
rlim.rlim_cur, _rtld_get_stack_prot());
}
#pragma weak __pthread_map_stacks_exec
void
__pthread_map_stacks_exec(void)
{
((void (*)(void))__libc_interposing[INTERPOS_map_stacks_exec])();
}
void
__libc_distribute_static_tls(size_t offset, void *src, size_t len,
size_t total_len)
{
uintptr_t tlsbase;
tlsbase = _libc_get_static_tls_base(offset);
memcpy((void *)tlsbase, src, len);
memset((char *)tlsbase + len, 0, total_len - len);
}
#pragma weak __pthread_distribute_static_tls
void
__pthread_distribute_static_tls(size_t offset, void *src, size_t len,
size_t total_len)
{
((void (*)(size_t, void *, size_t, size_t))__libc_interposing[
INTERPOS_distribute_static_tls])(offset, src, len, total_len);
}