From 9fc813e1a37d2e2d5e85a97d5ac4fc1c15d839fb Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Mon, 1 Mar 2021 15:56:36 +0100 Subject: Implement for dynamically loading the libgcc_s unwinder This will be used to consolidate the libgcc_s access for backtrace and pthread_cancel. Unlike the existing backtrace implementations, it provides some hardening based on pointer mangling. Reviewed-by: Carlos O'Donell --- sysdeps/generic/unwind-arch.h | 27 ++++++----- sysdeps/generic/unwind-link.h | 106 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 122 insertions(+), 11 deletions(-) create mode 100644 sysdeps/generic/unwind-link.h (limited to 'sysdeps/generic') diff --git a/sysdeps/generic/unwind-arch.h b/sysdeps/generic/unwind-arch.h index feda585e8d..ead6674279 100644 --- a/sysdeps/generic/unwind-arch.h +++ b/sysdeps/generic/unwind-arch.h @@ -1,5 +1,5 @@ -/* Return backtrace of current program state. Arch-specific bits. - Copyright (C) 2020-2021 Free Software Foundation, Inc. +/* Dynamic loading of the libgcc unwinder. Generic version of parameters. + Copyright (C) 2021 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 @@ -16,15 +16,20 @@ License along with the GNU C Library; if not, see . */ -#ifndef _UNWIND_ARCH_H -#define _UNWIND_ARCH_H +#ifndef _ARCH_UNWIND_LINK_H +#define _ARCH_UNWIND_LINK_H -#include +/* The _Unwind_GetIP function is supported. */ +#define UNWIND_LINK_GETIP 1 -static inline void * -unwind_arch_adjustment (void *prev, void *addr) -{ - return addr; -} +/* The __frame_state_for function is needed and re-exported from glibc. */ +#define UNWIND_LINK_FRAME_STATE_FOR 0 -#endif +/* No adjustment of the is needed. */ +#define UNWIND_LINK_FRAME_ADJUSTMENT 0 + +/* There are no extra fields in struct unwind_link in the generic version. */ +#define UNWIND_LINK_EXTRA_FIELDS +#define UNWIND_LINK_EXTRA_INIT + +#endif /* _ARCH_UNWIND_LINK_H */ diff --git a/sysdeps/generic/unwind-link.h b/sysdeps/generic/unwind-link.h new file mode 100644 index 0000000000..3527cebe2d --- /dev/null +++ b/sysdeps/generic/unwind-link.h @@ -0,0 +1,106 @@ +/* Dynamic loading of the libgcc unwinder. Generic version. + Copyright (C) 2021 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 + . */ + +#ifndef _UNWIND_LINK_H +#define _UNWIND_LINK_H + +#include +#include + +#if !UNWIND_LINK_FRAME_ADJUSTMENT +static inline void * +unwind_arch_adjustment (void *prev, void *addr) +{ + return addr; +} +#endif + +#ifdef SHARED +# include +# include + +# if UNWIND_LINK_FRAME_STATE_FOR +struct frame_state; +# endif + +struct unwind_link +{ + __typeof (_Unwind_Backtrace) *ptr__Unwind_Backtrace; + __typeof (_Unwind_ForcedUnwind) *ptr__Unwind_ForcedUnwind; + __typeof (_Unwind_GetCFA) *ptr__Unwind_GetCFA; +# if UNWIND_LINK_GETIP + __typeof (_Unwind_GetIP) *ptr__Unwind_GetIP; +# endif + __typeof (_Unwind_Resume) *ptr__Unwind_Resume; +#if UNWIND_LINK_FRAME_STATE_FOR + struct frame_state *(*ptr___frame_state_for) (void *, struct frame_state *); +#endif + _Unwind_Reason_Code (*ptr_personality) PERSONALITY_PROTO; + UNWIND_LINK_EXTRA_FIELDS +}; + +/* Return a pointer to the implementation, or NULL on failure. */ +struct unwind_link *__libc_unwind_link_get (void); +libc_hidden_proto (__libc_unwind_link_get) + +/* UNWIND_LINK_PTR returns the stored function pointer NAME from the + cached unwind link OBJ (which was previously returned by + __libc_unwind_link_get). */ +# ifdef PTR_DEMANGLE +# define UNWIND_LINK_PTR(obj, name, ...) \ + ({ \ + __typeof ((obj)->ptr_##name) __unwind_fptr = (obj)->ptr_##name; \ + PTR_DEMANGLE (__unwind_fptr); \ + __unwind_fptr; \ + }) +# else /* !PTR_DEMANGLE */ +# define UNWIND_LINK_PTR(obj, name, ...) ((obj)->ptr_##name) +# endif + +/* Called from fork, in the new subprocess. */ +void __libc_unwind_link_after_fork (void); + +/* Called from __libc_freeres. */ +void __libc_unwind_link_freeres (void) attribute_hidden; + +#else /* !SHARED */ + +/* Dummy implementation so that the code can be shared with the SHARED + version. */ +struct unwind_link; +static inline struct unwind_link * +__libc_unwind_link_get (void) +{ + /* Return something that is not a null pointer, so that error checks + succeed. */ + return (struct unwind_link *) 1; +} + +/* Directly call the static implementation. */ +# define UNWIND_LINK_PTR(obj, name, ...) \ + ((void) (obj), &name) + +static inline void +__libc_unwind_link_after_fork (void) +{ + /* No need to clean up if the unwinder is statically linked. */ +} + +#endif /* !SHARED */ + +#endif /* _UNWIND_LINK_H */ -- cgit 1.4.1