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IABSD.fr/src/libexec/ld.so/resolve.h

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  • Author : guenther
    Date : 2021-11-12 22:28:13
    Hash : b3331980
    Message : Add support for RELR relocations in the executable and share objects. This doesn't affect ld.so's self-reloc, which still requires DT_REL/DT_RELA ok kettenis@

  • libexec/ld.so/resolve.h 
  • /*	$OpenBSD: resolve.h,v 1.99 2021/11/12 22:28:13 guenther Exp $ */

/*
 * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
 *
 * 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. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
 *
 */

#ifndef _RESOLVE_H_
#define _RESOLVE_H_

#include <sys/queue.h>
#include <dlfcn.h>
#include <link.h>
#include <tib.h>

#define __relro		__attribute__((section(".data.rel.ro")))

#ifndef __boot
# if DO_CLEAN_BOOT
#  define __boot	__attribute__((section(".boot.text")))
#  define __boot_data	__attribute__((section(".boot.data")))
# else
#  define __boot
#  define __boot_data
# endif
#endif

/* Number of low tags that are used saved internally (0 .. DT_NUM-1) */
#define DT_NUM	(DT_RELR + 1)

struct load_list {
	struct load_list *next;
	void		*start;
	size_t		size;
	int		prot;
	Elf_Addr	moff;
	long		foff;
};

typedef void initarrayfunc(int, const char **, char **, dl_cb_cb *);
typedef void initfunc(void);	/* also fini and fini_array functions */

/* Alpha uses 8byte entries for DT_HASH */
#ifdef __alpha__
typedef uint64_t Elf_Hash_Word;
#else
typedef uint32_t Elf_Hash_Word;
#endif

typedef struct elf_object elf_object_t;

struct object_vector {
	int		len;
	int		alloc;
	elf_object_t 	**vec;
};
void	object_vec_grow(struct object_vector *_vec, int _more);

/*
 *  Structure describing a loaded object.
 *  The head of this struct must be compatible
 *  with struct link_map in sys/link.h
 */
struct elf_object {
	Elf_Addr obj_base;		/* object's address '0' base */
	char	*load_name;		/* Pointer to object name */
	Elf_Dyn *load_dyn;		/* Pointer to object dynamic data */
	struct elf_object *next;
	struct elf_object *prev;
/* End struct link_map compatible */
	Elf_Addr load_base;		/* Base address of loadable segments */

	struct load_list *load_list;

	u_int32_t  load_size;

	union {
		u_long		info[DT_NUM + DT_PROCNUM];
		struct {
			Elf_Addr	null;		/* Not used */
			Elf_Addr	needed;		/* Not used */
			Elf_Addr	pltrelsz;
			Elf_Addr	*pltgot;
			Elf_Addr	*hash;
			const char	*strtab;
			const Elf_Sym	*symtab;
			Elf_RelA	*rela;
			Elf_Addr	relasz;
			Elf_Addr	relaent;
			Elf_Addr	strsz;
			Elf_Addr	syment;
			initfunc	*init;
			initfunc	*fini;
			const char	*soname;
			const char	*rpath;
			Elf_Addr	symbolic;
			Elf_Rel		*rel;
			Elf_Addr	relsz;
			Elf_Addr	relent;
			Elf_Addr	pltrel;
			Elf_Addr	debug;
			Elf_Addr	textrel;
			Elf_Addr	jmprel;
			Elf_Addr	bind_now;
			initarrayfunc	**init_array;
			initfunc	**fini_array;
			Elf_Addr	init_arraysz;
			Elf_Addr	fini_arraysz;
			const char	*runpath;
			Elf_Addr	flags;
			Elf_Addr	encoding;
			initarrayfunc	**preinit_array;
			Elf_Addr	preinit_arraysz;
			Elf_Addr	unassigned;
			Elf_Addr	relrsz;
			Elf_Relr	*relr;
		} u;
	} Dyn;
#define dyn Dyn.u

	Elf_Addr	relacount;	/* DT_RELACOUNT */
	Elf_Addr	relcount;	/* DT_RELCOUNT */

	int		status;
#define	STAT_RELOC_DONE		0x001
#define	STAT_GOT_DONE		0x002
#define	STAT_INIT_DONE		0x004
#define	STAT_FINI_DONE		0x008
#define	STAT_FINI_READY		0x010
#define	STAT_UNLOADED		0x020
#define	STAT_NODELETE		0x040
#define	STAT_GNU_HASH		0x080
#define	STAT_VISIT_INITFIRST	0x100
#define	STAT_VISIT_INIT		0x200

	Elf_Phdr	*phdrp;
	int		phdrc;

	int		obj_type;
#define	OBJTYPE_LDR	1
#define	OBJTYPE_EXE	2
#define	OBJTYPE_LIB	3
#define	OBJTYPE_DLO	4
	int		obj_flags;	/* c.f. <sys/exec_elf.h> DF_1_* */

	/* shared by ELF and GNU hash */
	u_int32_t	nbuckets;
	u_int32_t	nchains;	/* really, number of symbols */
	union {
		struct {
			/* specific to ELF hash */
			const Elf_Hash_Word	*buckets;
			const Elf_Hash_Word	*chains;
		} u_elf;
		struct {
			/* specific to GNU hash */
			const Elf_Word		*buckets;
			const Elf_Word		*chains;
			const Elf_Addr		*bloom;
			Elf_Word		mask_bm;
			Elf_Word		shift2;
			Elf_Word		symndx;
		} u_gnu;
	} hash_u;
#define buckets_elf	hash_u.u_elf.buckets
#define chains_elf	hash_u.u_elf.chains
#define buckets_gnu	hash_u.u_gnu.buckets
#define chains_gnu	hash_u.u_gnu.chains
#define bloom_gnu	hash_u.u_gnu.bloom
#define mask_bm_gnu	hash_u.u_gnu.mask_bm
#define shift2_gnu	hash_u.u_gnu.shift2
#define symndx_gnu	hash_u.u_gnu.symndx

	struct object_vector	child_vec;	/* direct dep libs of object */
	struct object_vector	grpsym_vec;	/* ordered complete dep list */
	TAILQ_HEAD(,dep_node)	grpref_list;	/* refs to other load groups */

	int		refcount;	/* dep libs only */
	int		opencount;	/* # dlopen() & exe */
	int		grprefcount;	/* load group refs */
#define OBJECT_REF_CNT(object) \
    ((object->refcount + object->opencount + object->grprefcount))
#define OBJECT_DLREF_CNT(object) \
    ((object->opencount + object->grprefcount))

	/* object that caused this module to be loaded, used in symbol lookup */
	elf_object_t	*load_object;
	struct sod	sod;

	/* for object confirmation */
	dev_t	dev;
	ino_t inode;

	/* thread local storage info */
	Elf_Addr	tls_fsize;
	Elf_Addr	tls_msize;
	Elf_Addr	tls_align;
	const void	*tls_static_data;
	int		tls_offset;

	/* relro bits */
	Elf_Addr	relro_addr;
	Elf_Addr	relro_size;

	/* generation number of last grpsym insert on this object */
	unsigned int grpsym_gen;

	char **rpath;
	char **runpath;

	/* nonzero if trace enabled for this object */
	int traced;
};

struct dep_node {
	TAILQ_ENTRY(dep_node) next_sib;
	elf_object_t *data;
};


/* Please don't rename or make hidden; gdb(1) knows about these. */
Elf_Addr _dl_bind(elf_object_t *object, int index);
void	_dl_debug_state(void);

/* exported to the application */
extern char *__progname;

__BEGIN_HIDDEN_DECLS
void _dl_handle_nodelete(elf_object_t *_object);
void _dl_add_object(elf_object_t *object);
elf_object_t *_dl_finalize_object(const char *objname, Elf_Dyn *dynp,
    Elf_Phdr *phdrp, int phdrc, const int objtype, const long lbase,
    const long obase);
void	_dl_remove_object(elf_object_t *object);
void	_dl_cleanup_objects(void);

elf_object_t *_dl_load_shlib(const char *, elf_object_t *, int, int);
elf_object_t *_dl_tryload_shlib(const char *libname, int type, int flags);

int _dl_md_reloc(elf_object_t *object, int rel, int relsz);
int _dl_md_reloc_got(elf_object_t *object, int lazy);

struct sym_res {
	const Elf_Sym		*sym;
	const elf_object_t	*obj;
};

struct sym_res _dl_find_symbol(const char *name, int flags,
    const Elf_Sym *ref_sym, elf_object_t *object);

/*
 * defines for _dl_find_symbol() flag field, three bits of meaning
 * myself	- clear: search all objects,	set: search only this object
 * warnnotfound - clear: no warning,		set: warn if not found
 * inplt	- clear: possible plt ref	set: real matching function.
 *
 * inplt - due to how ELF handles function addresses in shared libraries
 * &func may actually refer to the plt entry in the main program
 * rather than the actual function address in the .so file.
 * This rather bizarre behavior is documented in the SVR4 ABI.
 * when getting the function address to relocate a PLT entry
 * the 'real' function address is necessary, not the possible PLT address.
 */
/* myself */
#define SYM_SEARCH_ALL		0x00
#define SYM_SEARCH_SELF		0x01
#define SYM_SEARCH_OTHER	0x02
#define SYM_SEARCH_NEXT		0x04
/* warnnotfound */
#define SYM_NOWARNNOTFOUND	0x00
#define SYM_WARNNOTFOUND	0x10
/* inplt */
#define SYM_NOTPLT		0x00
#define SYM_PLT			0x20

#define SYM_DLSYM		0x40

int _dl_load_dep_libs(elf_object_t *object, int flags, int booting);
int _dl_rtld(elf_object_t *object);
void _dl_call_init(elf_object_t *object);
void _dl_link_child(elf_object_t *dep, elf_object_t *p);
void _dl_link_grpsym(elf_object_t *object);
void _dl_cache_grpsym_list_setup(elf_object_t *_object);
void _dl_link_grpref(elf_object_t *load_group, elf_object_t *load_object);
void _dl_link_dlopen(elf_object_t *dep);
void _dl_unlink_dlopen(elf_object_t *dep);
void _dl_notify_unload_shlib(elf_object_t *object);
void _dl_unload_shlib(elf_object_t *object);
void _dl_unload_dlopen(void);

void _dl_run_all_dtors(void);

int	_dl_match_file(struct sod *sodp, const char *name, int namelen);
char	*_dl_find_shlib(struct sod *sodp, char **searchpath, int nohints);
void	_dl_load_list_free(struct load_list *load_list);

typedef void lock_cb(int);
void	_dl_thread_kern_go(lock_cb *);
lock_cb	*_dl_thread_kern_stop(void);

char	*_dl_getenv(const char *, char **) __boot;
void	_dl_unsetenv(const char *, char **) __boot;

void	_dl_trace_setup(char **) __boot;
void	_dl_trace_object_setup(elf_object_t *);
int	_dl_trace_plt(const elf_object_t *, const char *);

/* tib.c */
void	_dl_allocate_tls_offsets(void) __boot;
void	_dl_allocate_first_tib(void) __boot;
void	_dl_set_tls(elf_object_t *_object, Elf_Phdr *_ptls, Elf_Addr _libaddr,
	    const char *_libname);
extern int _dl_tib_static_done;

extern elf_object_t *_dl_objects;
extern int object_count;	/* how many objects are currently loaded */

extern elf_object_t *_dl_loading_object;

extern struct r_debug *_dl_debug_map;

extern int  _dl_pagesz;
extern int  _dl_errno;

extern char **_dl_libpath;

extern int _dl_bindnow;
extern int _dl_traceld;
extern int _dl_debug;

extern char *_dl_preload;
extern char *_dl_tracefmt1;
extern char *_dl_tracefmt2;
extern char *_dl_traceprog;

extern void *_dl_exec_hint;

extern int _dl_trust;

#define DL_DEB(P) do { if (_dl_debug) _dl_printf P ; } while (0)

#define	DL_NOT_FOUND		1
#define	DL_CANT_OPEN		2
#define	DL_NOT_ELF		3
#define	DL_CANT_OPEN_REF	4
#define	DL_CANT_MMAP		5
#define	DL_NO_SYMBOL		6
#define	DL_INVALID_HANDLE	7
#define	DL_INVALID_CTL		8
#define	DL_NO_OBJECT		9
#define	DL_CANT_FIND_OBJ	10
#define	DL_CANT_LOAD_OBJ	11
#define	DL_INVALID_MODE		12

#define ELF_ROUND(x,malign) (((x) + (malign)-1) & ~((malign)-1))
#define ELF_TRUNC(x,malign) ((x) & ~((malign)-1))

/* symbol lookup cache */
typedef struct sym_cache {
	const elf_object_t *obj;
	const Elf_Sym	*sym;
	int flags;
} sym_cache;

TAILQ_HEAD(dlochld, dep_node);
extern struct dlochld _dlopened_child_list;
__END_HIDDEN_DECLS

#endif /* _RESOLVE_H_ */