/* Data structure for communication from the run-time dynamic linker for loaded ELF shared objects. Copyright (C) 1995-2020 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/>. */ #ifndef _LINK_H #define _LINK_H 1 #include <features.h> #include <elf.h> #include <dlfcn.h> #include <sys/types.h> /* We use this macro to refer to ELF types independent of the native wordsize. `ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'. */ #define ElfW(type) _ElfW (Elf, __ELF_NATIVE_CLASS, type) #define _ElfW(e,w,t) _ElfW_1 (e, w, _##t) #define _ElfW_1(e,w,t) e##w##t #include <bits/elfclass.h> /* Defines __ELF_NATIVE_CLASS. */ #include <bits/link.h> /* Rendezvous structure used by the run-time dynamic linker to communicate details of shared object loading to the debugger. If the executable's dynamic section has a DT_DEBUG element, the run-time linker sets that element's value to the address where this structure can be found. */ struct r_debug { int r_version; /* Version number for this protocol. */ struct link_map *r_map; /* Head of the chain of loaded objects. */ /* This is the address of a function internal to the run-time linker, that will always be called when the linker begins to map in a library or unmap it, and again when the mapping change is complete. The debugger can set a breakpoint at this address if it wants to notice shared object mapping changes. */ ElfW(Addr) r_brk; enum { /* This state value describes the mapping change taking place when the `r_brk' address is called. */ RT_CONSISTENT, /* Mapping change is complete. */ RT_ADD, /* Beginning to add a new object. */ RT_DELETE /* Beginning to remove an object mapping. */ } r_state; ElfW(Addr) r_ldbase; /* Base address the linker is loaded at. */ }; /* This is the instance of that structure used by the dynamic linker. */ extern struct r_debug _r_debug; /* This symbol refers to the "dynamic structure" in the `.dynamic' section of whatever module refers to `_DYNAMIC'. So, to find its own `struct r_debug', a program could do: for (dyn = _DYNAMIC; dyn->d_tag != DT_NULL; ++dyn) if (dyn->d_tag == DT_DEBUG) r_debug = (struct r_debug *) dyn->d_un.d_ptr; */ extern ElfW(Dyn) _DYNAMIC[]; /* Structure describing a loaded shared object. The `l_next' and `l_prev' members form a chain of all the shared objects loaded at startup. These data structures exist in space used by the run-time dynamic linker; modifying them may have disastrous results. */ struct link_map { /* These first few members are part of the protocol with the debugger. This is the same format used in SVR4. */ ElfW(Addr) l_addr; /* Difference between the address in the ELF file and the addresses in memory. */ char *l_name; /* Absolute file name object was found in. */ ElfW(Dyn) *l_ld; /* Dynamic section of the shared object. */ struct link_map *l_next, *l_prev; /* Chain of loaded objects. */ }; #ifdef __USE_GNU /* Version numbers for la_version handshake interface. */ #define LAV_CURRENT 1 /* Activity types signaled through la_activity. */ enum { LA_ACT_CONSISTENT, /* Link map consistent again. */ LA_ACT_ADD, /* New object will be added. */ LA_ACT_DELETE /* Objects will be removed. */ }; /* Values representing origin of name for dynamic loading. */ enum { LA_SER_ORIG = 0x01, /* Original name. */ LA_SER_LIBPATH = 0x02, /* Directory from LD_LIBRARY_PATH. */ LA_SER_RUNPATH = 0x04, /* Directory from RPATH/RUNPATH. */ LA_SER_CONFIG = 0x08, /* Found through ldconfig. */ LA_SER_DEFAULT = 0x40, /* Default directory. */ LA_SER_SECURE = 0x80 /* Unused. */ }; /* Values for la_objopen return value. */ enum { LA_FLG_BINDTO = 0x01, /* Audit symbols bound to this object. */ LA_FLG_BINDFROM = 0x02 /* Audit symbols bound from this object. */ }; /* Values for la_symbind flags parameter. */ enum { LA_SYMB_NOPLTENTER = 0x01, /* la_pltenter will not be called. */ LA_SYMB_NOPLTEXIT = 0x02, /* la_pltexit will not be called. */ LA_SYMB_STRUCTCALL = 0x04, /* Return value is a structure. */ LA_SYMB_DLSYM = 0x08, /* Binding due to dlsym call. */ LA_SYMB_ALTVALUE = 0x10 /* Value has been changed by a previous la_symbind call. */ }; struct dl_phdr_info { ElfW(Addr) dlpi_addr; const char *dlpi_name; const ElfW(Phdr) *dlpi_phdr; ElfW(Half) dlpi_phnum; /* Note: Following members were introduced after the first version of this structure was available. Check the SIZE argument passed to the dl_iterate_phdr callback to determine whether or not each later member is available. */ /* Incremented when a new object may have been added. */ __extension__ unsigned long long int dlpi_adds; /* Incremented when an object may have been removed. */ __extension__ unsigned long long int dlpi_subs; /* If there is a PT_TLS segment, its module ID as used in TLS relocations, else zero. */ size_t dlpi_tls_modid; /* The address of the calling thread's instance of this module's PT_TLS segment, if it has one and it has been allocated in the calling thread, otherwise a null pointer. */ void *dlpi_tls_data; }; __BEGIN_DECLS extern int dl_iterate_phdr (int (*__callback) (struct dl_phdr_info *, size_t, void *), void *__data); /* Prototypes for the ld.so auditing interfaces. These are not defined anywhere in ld.so but instead have to be provided by the auditing DSO. */ extern unsigned int la_version (unsigned int __version); extern void la_activity (uintptr_t *__cookie, unsigned int __flag); extern char *la_objsearch (const char *__name, uintptr_t *__cookie, unsigned int __flag); extern unsigned int la_objopen (struct link_map *__map, Lmid_t __lmid, uintptr_t *__cookie); extern void la_preinit (uintptr_t *__cookie); extern uintptr_t la_symbind32 (Elf32_Sym *__sym, unsigned int __ndx, uintptr_t *__refcook, uintptr_t *__defcook, unsigned int *__flags, const char *__symname); extern uintptr_t la_symbind64 (Elf64_Sym *__sym, unsigned int __ndx, uintptr_t *__refcook, uintptr_t *__defcook, unsigned int *__flags, const char *__symname); extern unsigned int la_objclose (uintptr_t *__cookie); __END_DECLS #endif #endif /* link.h */