From c7aa8596de86fb667914ccb95c10495ad056ff96 Mon Sep 17 00:00:00 2001 From: Szabolcs Nagy Date: Mon, 22 Jun 2020 10:56:38 +0100 Subject: rtld: Clean up PT_NOTE and add PT_GNU_PROPERTY handling Add generic code to handle PT_GNU_PROPERTY notes. Invalid content is ignored, _dl_process_pt_gnu_property is always called after PT_LOAD segments are mapped and it has no failure modes. Currently only one NT_GNU_PROPERTY_TYPE_0 note is handled, which contains target specific properties: the _dl_process_gnu_property hook is called for each property. The old _dl_process_pt_note and _rtld_process_pt_note differ in how the program header is read. The old _dl_process_pt_note is called before PT_LOAD segments are mapped and _rtld_process_pt_note is called after PT_LOAD segments are mapped. The old _rtld_process_pt_note is removed and _dl_process_pt_note is always called after PT_LOAD segments are mapped and now it has no failure modes. The program headers are scanned backwards so that PT_NOTE can be skipped if PT_GNU_PROPERTY exists. Co-Authored-By: H.J. Lu Reviewed-by: Adhemerval Zanella --- sysdeps/generic/dl-prop.h | 23 +++++++++++------------ sysdeps/generic/ldsodefs.h | 4 ++++ 2 files changed, 15 insertions(+), 12 deletions(-) (limited to 'sysdeps/generic') diff --git a/sysdeps/generic/dl-prop.h b/sysdeps/generic/dl-prop.h index 6b0f2aa95a..f1cf576fe3 100644 --- a/sysdeps/generic/dl-prop.h +++ b/sysdeps/generic/dl-prop.h @@ -20,11 +20,11 @@ #define _DL_PROP_H /* The following functions are used by the dynamic loader and the - dlopen machinery to process PT_NOTE entries in the binary or - shared object. The notes can be used to change the behaviour of - the loader, and as such offer a flexible mechanism for hooking in - various checks related to ABI tags or implementing "flag day" ABI - transitions. */ + dlopen machinery to process PT_NOTE and PT_GNU_PROPERTY entries in + the binary or shared object. The notes can be used to change the + behaviour of the loader, and as such offer a flexible mechanism + for hooking in various checks related to ABI tags or implementing + "flag day" ABI transitions. */ static inline void __attribute__ ((always_inline)) _rtld_main_check (struct link_map *m, const char *program) @@ -36,17 +36,16 @@ _dl_open_check (struct link_map *m) { } -#ifdef FILEBUF_SIZE -static inline int __attribute__ ((always_inline)) -_dl_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph, - int fd, struct filebuf *fbp) +static inline void __attribute__ ((always_inline)) +_dl_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph) { - return 0; } -#endif +/* Called for each property in the NT_GNU_PROPERTY_TYPE_0 note of L, + processing of the properties continues until this returns 0. */ static inline int __attribute__ ((always_inline)) -_rtld_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph) +_dl_process_gnu_property (struct link_map *l, uint32_t type, uint32_t datasz, + void *data) { return 0; } diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h index d08b97a5ef..c525ffa12c 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -910,6 +910,10 @@ extern void _dl_setup_hash (struct link_map *map) attribute_hidden; extern void _dl_rtld_di_serinfo (struct link_map *loader, Dl_serinfo *si, bool counting); +/* Process PT_GNU_PROPERTY program header PH in module L after + PT_LOAD segments are mapped. */ +void _dl_process_pt_gnu_property (struct link_map *l, const ElfW(Phdr) *ph); + /* Search loaded objects' symbol tables for a definition of the symbol referred to by UNDEF. *SYM is the symbol table entry containing the -- cgit v1.2.1