diff options
| -rw-r--r-- | csu/libc-tls.c | 11 | ||||
| -rw-r--r-- | elf/Makefile | 19 | ||||
| -rw-r--r-- | elf/dl-early_allocate.c | 30 | ||||
| -rw-r--r-- | elf/tst-tls-allocation-failure-static.c | 31 | ||||
| -rw-r--r-- | scripts/tst-elf-edit.py | 34 | ||||
| -rw-r--r-- | sysdeps/generic/ldsodefs.h | 5 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/dl-early_allocate.c | 82 |
7 files changed, 202 insertions, 10 deletions
diff --git a/csu/libc-tls.c b/csu/libc-tls.c index bef92a7..0a216c5 100644 --- a/csu/libc-tls.c +++ b/csu/libc-tls.c @@ -145,11 +145,16 @@ __libc_setup_tls (void) _dl_allocate_tls_storage (in elf/dl-tls.c) does using __libc_memalign and dl_tls_static_align. */ tcb_offset = roundup (memsz + GLRO(dl_tls_static_surplus), max_align); - tlsblock = __sbrk (tcb_offset + TLS_INIT_TCB_SIZE + max_align); + tlsblock = _dl_early_allocate (tcb_offset + TLS_INIT_TCB_SIZE + max_align); + if (tlsblock == NULL) + _startup_fatal ("Fatal glibc error: Cannot allocate TLS block\n"); #elif TLS_DTV_AT_TP tcb_offset = roundup (TLS_INIT_TCB_SIZE, align ?: 1); - tlsblock = __sbrk (tcb_offset + memsz + max_align - + TLS_PRE_TCB_SIZE + GLRO(dl_tls_static_surplus)); + tlsblock = _dl_early_allocate (tcb_offset + memsz + max_align + + TLS_PRE_TCB_SIZE + + GLRO(dl_tls_static_surplus)); + if (tlsblock == NULL) + _startup_fatal ("Fatal glibc error: Cannot allocate TLS block\n"); tlsblock += TLS_PRE_TCB_SIZE; #else /* In case a model with a different layout for the TCB and DTV diff --git a/elf/Makefile b/elf/Makefile index fc9860e..ce3345e 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -33,6 +33,7 @@ routines = \ $(all-dl-routines) \ dl-addr \ dl-addr-obj \ + dl-early_allocate \ dl-error \ dl-iteratephdr \ dl-libc \ @@ -108,6 +109,7 @@ all-dl-routines = $(dl-routines) $(sysdep-dl-routines) # But they are absent from the shared libc, because that code is in ld.so. elide-routines.os = \ $(all-dl-routines) \ + dl-early_allocate \ dl-exception \ dl-origin \ dl-reloc-static-pie \ @@ -276,6 +278,7 @@ tests-static-normal := \ tst-linkall-static \ tst-single_threaded-pthread-static \ tst-single_threaded-static \ + tst-tls-allocation-failure-static \ tst-tlsalign-extern-static \ tst-tlsalign-static \ # tests-static-normal @@ -1213,6 +1216,10 @@ $(objpfx)tst-glibcelf.out: tst-glibcelf.py elf.h $(..)/scripts/glibcelf.py \ --cc="$(CC) $(patsubst -DMODULE_NAME=%,-DMODULE_NAME=testsuite,$(CPPFLAGS))" \ < /dev/null > $@ 2>&1; $(evaluate-test) +ifeq ($(run-built-tests),yes) +tests-special += $(objpfx)tst-tls-allocation-failure-static-patched.out +endif + # The test requires shared _and_ PIE because the executable # unit test driver must be able to link with the shared object # that is going to eventually go into an installed DSO. @@ -2937,3 +2944,15 @@ $(eval $(call tst-trace-skeleton,4,\ $(objpfx)libtracemod2:$(objpfx)libtracemod3:$(objpfx)libtracemod4)) $(eval $(call tst-trace-skeleton,5,\ $(objpfx)libtracemod2:$(objpfx)libtracemod3:$(objpfx)libtracemod4:$(objpfx)libtracemod5)) + +$(objpfx)tst-tls-allocation-failure-static-patched: \ + $(objpfx)tst-tls-allocation-failure-static $(..)scripts/tst-elf-edit.py + cp $< $@ + $(PYTHON) $(..)scripts/tst-elf-edit.py --maximize-tls-size $@ + +$(objpfx)tst-tls-allocation-failure-static-patched.out: \ + $(objpfx)tst-tls-allocation-failure-static-patched + $< > $@ 2>&1; echo "status: $$?" >> $@ + grep -q '^Fatal glibc error: Cannot allocate TLS block$$' $@ \ + && grep -q '^status: 127$$' $@; \ + $(evaluate-test) diff --git a/elf/dl-early_allocate.c b/elf/dl-early_allocate.c new file mode 100644 index 0000000..61677aa --- /dev/null +++ b/elf/dl-early_allocate.c @@ -0,0 +1,30 @@ +/* Early memory allocation for the dynamic loader. Generic version. + Copyright (C) 2022 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +#include <ldsodefs.h> +#include <stddef.h> +#include <unistd.h> + +void * +_dl_early_allocate (size_t size) +{ + void *result = __sbrk (size); + if (result == (void *) -1) + result = NULL; + return result; +} diff --git a/elf/tst-tls-allocation-failure-static.c b/elf/tst-tls-allocation-failure-static.c new file mode 100644 index 0000000..8de831b --- /dev/null +++ b/elf/tst-tls-allocation-failure-static.c @@ -0,0 +1,31 @@ +/* Base for test program with impossiblyh large PT_TLS segment. + Copyright (C) 2022 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +/* The test actual binary is patched using scripts/tst-elf-edit.py + --maximize-tls-size, and this introduces the expected test + allocation failure due to an excessive PT_LS p_memsz value. + + Patching the binary is required because on some 64-bit targets, TLS + relocations can only cover a 32-bit range, and glibc-internal TLS + variables such as errno end up outside that range. */ + +int +main (void) +{ + return 0; +} diff --git a/scripts/tst-elf-edit.py b/scripts/tst-elf-edit.py index a514179..0e19ce1 100644 --- a/scripts/tst-elf-edit.py +++ b/scripts/tst-elf-edit.py @@ -43,9 +43,11 @@ EI_DATA=5 ELFDATA2LSB=b'\x01' ELFDATA2MSB=b'\x02' +ET_EXEC=2 ET_DYN=3 PT_LOAD=1 +PT_TLS=7 def elf_types_fmts(e_ident): endian = '<' if e_ident[EI_DATA] == ELFDATA2LSB else '>' @@ -146,8 +148,15 @@ def elf_edit_align(phdr, align): else: phdr.p_align = int(align) +def elf_edit_maximize_tls_size(phdr, elfclass): + if elfclass == ELFCLASS32: + # It is possible that the kernel can allocate half of the + # address space, so use something larger. + phdr.p_memsz = 0xfff00000 + else: + phdr.p_memsz = 1 << 63 -def elf_edit(f, align): +def elf_edit(f, opts): ei_nident_fmt = 'c' * EI_NIDENT ei_nident_len = struct.calcsize(ei_nident_fmt) @@ -172,24 +181,35 @@ def elf_edit(f, align): ehdr = Elf_Ehdr(e_ident) ehdr.read(f) - if ehdr.e_type != ET_DYN: - error('{}: not a shared library'.format(f.name)) + if ehdr.e_type not in (ET_EXEC, ET_DYN): + error('{}: not an executable or shared library'.format(f.name)) phdr = Elf_Phdr(e_ident) + maximize_tls_size_done = False for i in range(0, ehdr.e_phnum): f.seek(ehdr.e_phoff + i * phdr.len) phdr.read(f) - if phdr.p_type == PT_LOAD: - elf_edit_align(phdr, align) + if phdr.p_type == PT_LOAD and opts.align is not None: + elf_edit_align(phdr, opts.align) + f.seek(ehdr.e_phoff + i * phdr.len) + phdr.write(f) + break + if phdr.p_type == PT_TLS and opts.maximize_tls_size: + elf_edit_maximize_tls_size(phdr, e_ident[EI_CLASS]) f.seek(ehdr.e_phoff + i * phdr.len) phdr.write(f) + maximize_tls_size_done = True break + if opts.maximize_tls_size and not maximize_tls_size_done: + error('{}: TLS maximum size was not updated'.format(f.name)) def get_parser(): parser = argparse.ArgumentParser(description=__doc__) - parser.add_argument('-a', dest='align', required=True, + parser.add_argument('-a', dest='align', help='How to set the LOAD alignment') + parser.add_argument('--maximize-tls-size', action='store_true', + help='Set maximum PT_TLS size') parser.add_argument('output', help='ELF file to edit') return parser @@ -199,7 +219,7 @@ def main(argv): parser = get_parser() opts = parser.parse_args(argv) with open(opts.output, 'r+b') as fout: - elf_edit(fout, opts.align) + elf_edit(fout, opts) if __name__ == '__main__': diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h index 4a5e698..5d03693 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -1211,6 +1211,11 @@ extern struct link_map * _dl_get_dl_main_map (void) # endif #endif +/* Perform early memory allocation, avoding a TCB dependency. + Terminate the process if allocation fails. May attempt to use + brk. */ +void *_dl_early_allocate (size_t size) attribute_hidden; + /* Initialize the DSO sort algorithm to use. */ #if !HAVE_TUNABLES static inline void diff --git a/sysdeps/unix/sysv/linux/dl-early_allocate.c b/sysdeps/unix/sysv/linux/dl-early_allocate.c new file mode 100644 index 0000000..52c538e --- /dev/null +++ b/sysdeps/unix/sysv/linux/dl-early_allocate.c @@ -0,0 +1,82 @@ +/* Early memory allocation for the dynamic loader. Generic version. + Copyright (C) 2022 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +/* Mark symbols hidden in static PIE for early self relocation to work. */ +#if BUILD_PIE_DEFAULT +# pragma GCC visibility push(hidden) +#endif +#include <startup.h> + +#include <ldsodefs.h> +#include <stddef.h> +#include <string.h> +#include <sysdep.h> +#include <unistd.h> + +#include <brk_call.h> +#include <mmap_call.h> + +/* Defined in brk.c. */ +extern void *__curbrk; + +void * +_dl_early_allocate (size_t size) +{ + void *result; + + if (__curbrk != NULL) + /* If the break has been initialized, brk must have run before, + so just call it once more. */ + { + result = __sbrk (size); + if (result == (void *) -1) + result = NULL; + } + else + { + /* If brk has not been invoked, there is no need to update + __curbrk. The first call to brk will take care of that. */ + void *previous = __brk_call (0); + result = __brk_call (previous + size); + if (result == previous) + result = NULL; + else + result = previous; + } + + /* If brk fails, fall back to mmap. This can happen due to + unfortunate ASLR layout decisions and kernel bugs, particularly + for static PIE. */ + if (result == NULL) + { + long int ret; + int prot = PROT_READ | PROT_WRITE; + int flags = MAP_PRIVATE | MAP_ANONYMOUS; +#ifdef __NR_mmap2 + ret = MMAP_CALL_INTERNAL (mmap2, 0, size, prot, flags, -1, 0); +#else + ret = MMAP_CALL_INTERNAL (mmap, 0, size, prot, flags, -1, 0); +#endif + if (INTERNAL_SYSCALL_ERROR_P (ret)) + result = NULL; + else + result = (void *) ret; + } + + return result; +} |