1
0
mirror of https://git.FreeBSD.org/src.git synced 2024-12-24 11:29:10 +00:00
freebsd/libexec/rtld-elf/rtld.h
Konstantin Belousov 8569deaf1c Implement support for ELF filters in rtld. Both normal and auxillary
filters are implemented.

Filtees are loaded on demand, unless LD_LOADFLTR environment variable
is set or -z loadfltr was specified during the linking. This forces
rtld to upgrade read-locked rtld_bind_lock to write lock when it
encounters an object with filter during symbol lookup.

Consolidate common arguments of the symbol lookup functions in the
SymLook structure.  Track the state of the rtld locks in the
RtldLockState structure. Pass local RtldLockState through the rtld
symbol lookup calls to allow lock upgrades.

Reviewed by:	kan
Tested by:	Mykola Dzham <i levsha me>, nwhitehorn (powerpc)
2010-12-25 08:51:20 +00:00

338 lines
12 KiB
C

/*-
* Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
* All rights reserved.
*
* 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.
*
* $FreeBSD$
*/
#ifndef RTLD_H /* { */
#define RTLD_H 1
#include <machine/elf.h>
#include <sys/types.h>
#include <sys/queue.h>
#include <elf-hints.h>
#include <link.h>
#include <setjmp.h>
#include <stddef.h>
#include "rtld_lock.h"
#include "rtld_machdep.h"
#ifdef COMPAT_32BIT
#undef STANDARD_LIBRARY_PATH
#undef _PATH_ELF_HINTS
#define _PATH_ELF_HINTS "/var/run/ld-elf32.so.hints"
/* For running 32 bit binaries */
#define STANDARD_LIBRARY_PATH "/lib32:/usr/lib32"
#define LD_ "LD_32_"
#endif
#ifndef STANDARD_LIBRARY_PATH
#define STANDARD_LIBRARY_PATH "/lib:/usr/lib"
#endif
#ifndef LD_
#define LD_ "LD_"
#endif
#define NEW(type) ((type *) xmalloc(sizeof(type)))
#define CNEW(type) ((type *) xcalloc(sizeof(type)))
/* We might as well do booleans like C++. */
typedef unsigned char bool;
#define false 0
#define true 1
extern size_t tls_last_offset;
extern size_t tls_last_size;
extern size_t tls_static_space;
extern int tls_dtv_generation;
extern int tls_max_index;
struct stat;
struct Struct_Obj_Entry;
/* Lists of shared objects */
typedef struct Struct_Objlist_Entry {
STAILQ_ENTRY(Struct_Objlist_Entry) link;
struct Struct_Obj_Entry *obj;
} Objlist_Entry;
typedef STAILQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
/* Types of init and fini functions */
typedef void (*InitFunc)(void);
/* Lists of shared object dependencies */
typedef struct Struct_Needed_Entry {
struct Struct_Needed_Entry *next;
struct Struct_Obj_Entry *obj;
unsigned long name; /* Offset of name in string table */
} Needed_Entry;
typedef struct Struct_Name_Entry {
STAILQ_ENTRY(Struct_Name_Entry) link;
char name[1];
} Name_Entry;
/* Lock object */
typedef struct Struct_LockInfo {
void *context; /* Client context for creating locks */
void *thelock; /* The one big lock */
/* Debugging aids. */
volatile int rcount; /* Number of readers holding lock */
volatile int wcount; /* Number of writers holding lock */
/* Methods */
void *(*lock_create)(void *context);
void (*rlock_acquire)(void *lock);
void (*wlock_acquire)(void *lock);
void (*rlock_release)(void *lock);
void (*wlock_release)(void *lock);
void (*lock_destroy)(void *lock);
void (*context_destroy)(void *context);
} LockInfo;
typedef struct Struct_Ver_Entry {
Elf_Word hash;
unsigned int flags;
const char *name;
const char *file;
} Ver_Entry;
#define VER_INFO_HIDDEN 0x01
/*
* Shared object descriptor.
*
* Items marked with "(%)" are dynamically allocated, and must be freed
* when the structure is destroyed.
*
* CAUTION: It appears that the JDK port peeks into these structures.
* It looks at "next" and "mapbase" at least. Don't add new members
* near the front, until this can be straightened out.
*/
typedef struct Struct_Obj_Entry {
/*
* These two items have to be set right for compatibility with the
* original ElfKit crt1.o.
*/
Elf_Size magic; /* Magic number (sanity check) */
Elf_Size version; /* Version number of struct format */
struct Struct_Obj_Entry *next;
char *path; /* Pathname of underlying file (%) */
char *origin_path; /* Directory path of origin file */
int refcount;
int dl_refcount; /* Number of times loaded by dlopen */
/* These items are computed by map_object() or by digest_phdr(). */
caddr_t mapbase; /* Base address of mapped region */
size_t mapsize; /* Size of mapped region in bytes */
size_t textsize; /* Size of text segment in bytes */
Elf_Addr vaddrbase; /* Base address in shared object file */
caddr_t relocbase; /* Relocation constant = mapbase - vaddrbase */
const Elf_Dyn *dynamic; /* Dynamic section */
caddr_t entry; /* Entry point */
const Elf_Phdr *phdr; /* Program header if it is mapped, else NULL */
size_t phsize; /* Size of program header in bytes */
const char *interp; /* Pathname of the interpreter, if any */
/* TLS information */
int tlsindex; /* Index in DTV for this module */
void *tlsinit; /* Base address of TLS init block */
size_t tlsinitsize; /* Size of TLS init block for this module */
size_t tlssize; /* Size of TLS block for this module */
size_t tlsoffset; /* Offset of static TLS block for this module */
size_t tlsalign; /* Alignment of static TLS block */
/* Items from the dynamic section. */
Elf_Addr *pltgot; /* PLT or GOT, depending on architecture */
const Elf_Rel *rel; /* Relocation entries */
unsigned long relsize; /* Size in bytes of relocation info */
const Elf_Rela *rela; /* Relocation entries with addend */
unsigned long relasize; /* Size in bytes of addend relocation info */
const Elf_Rel *pltrel; /* PLT relocation entries */
unsigned long pltrelsize; /* Size in bytes of PLT relocation info */
const Elf_Rela *pltrela; /* PLT relocation entries with addend */
unsigned long pltrelasize; /* Size in bytes of PLT addend reloc info */
const Elf_Sym *symtab; /* Symbol table */
const char *strtab; /* String table */
unsigned long strsize; /* Size in bytes of string table */
#ifdef __mips__
Elf_Word local_gotno; /* Number of local GOT entries */
Elf_Word symtabno; /* Number of dynamic symbols */
Elf_Word gotsym; /* First dynamic symbol in GOT */
#endif
const Elf_Verneed *verneed; /* Required versions. */
Elf_Word verneednum; /* Number of entries in verneed table */
const Elf_Verdef *verdef; /* Provided versions. */
Elf_Word verdefnum; /* Number of entries in verdef table */
const Elf_Versym *versyms; /* Symbol versions table */
const Elf_Hashelt *buckets; /* Hash table buckets array */
unsigned long nbuckets; /* Number of buckets */
const Elf_Hashelt *chains; /* Hash table chain array */
unsigned long nchains; /* Number of chains */
char *rpath; /* Search path specified in object */
Needed_Entry *needed; /* Shared objects needed by this one (%) */
Needed_Entry *needed_filtees;
Needed_Entry *needed_aux_filtees;
STAILQ_HEAD(, Struct_Name_Entry) names; /* List of names for this object we
know about. */
Ver_Entry *vertab; /* Versions required /defined by this object */
int vernum; /* Number of entries in vertab */
Elf_Addr init; /* Initialization function to call */
Elf_Addr fini; /* Termination function to call */
bool mainprog : 1; /* True if this is the main program */
bool rtld : 1; /* True if this is the dynamic linker */
bool textrel : 1; /* True if there are relocations to text seg */
bool symbolic : 1; /* True if generated with "-Bsymbolic" */
bool bind_now : 1; /* True if all relocations should be made first */
bool traced : 1; /* Already printed in ldd trace output */
bool jmpslots_done : 1; /* Already have relocated the jump slots */
bool init_done : 1; /* Already have added object to init list */
bool tls_done : 1; /* Already allocated offset for static TLS */
bool phdr_alloc : 1; /* Phdr is allocated and needs to be freed. */
bool z_origin : 1; /* Process rpath and soname tokens */
bool z_nodelete : 1; /* Do not unload the object and dependencies */
bool z_noopen : 1; /* Do not load on dlopen */
bool z_loadfltr : 1; /* Immediately load filtees */
bool ref_nodel : 1; /* Refcount increased to prevent dlclose */
bool init_scanned: 1; /* Object is already on init list. */
bool on_fini_list: 1; /* Object is already on fini list. */
bool dag_inited : 1; /* Object has its DAG initialized. */
bool filtees_loaded : 1; /* Filtees loaded */
struct link_map linkmap; /* For GDB and dlinfo() */
Objlist dldags; /* Object belongs to these dlopened DAGs (%) */
Objlist dagmembers; /* DAG has these members (%) */
dev_t dev; /* Object's filesystem's device */
ino_t ino; /* Object's inode number */
void *priv; /* Platform-dependant */
} Obj_Entry;
#define RTLD_MAGIC 0xd550b87a
#define RTLD_VERSION 1
#define RTLD_STATIC_TLS_EXTRA 128
/* Flags to be passed into symlook_ family of functions. */
#define SYMLOOK_IN_PLT 0x01 /* Lookup for PLT symbol */
#define SYMLOOK_DLSYM 0x02 /* Return newes versioned symbol. Used by
dlsym. */
/* Flags for load_object(). */
#define RTLD_LO_NOLOAD 0x01 /* dlopen() specified RTLD_NOLOAD. */
#define RTLD_LO_DLOPEN 0x02 /* Load_object() called from dlopen(). */
#define RTLD_LO_TRACE 0x04 /* Only tracing. */
#define RTLD_LO_NODELETE 0x08 /* Loaded object cannot be closed. */
#define RTLD_LO_FILTEES 0x10 /* Loading filtee. */
/*
* Symbol cache entry used during relocation to avoid multiple lookups
* of the same symbol.
*/
typedef struct Struct_SymCache {
const Elf_Sym *sym; /* Symbol table entry */
const Obj_Entry *obj; /* Shared object which defines it */
} SymCache;
/*
* This structure provides a reentrant way to keep a list of objects and
* check which ones have already been processed in some way.
*/
typedef struct Struct_DoneList {
const Obj_Entry **objs; /* Array of object pointers */
unsigned int num_alloc; /* Allocated size of the array */
unsigned int num_used; /* Number of array slots used */
} DoneList;
struct Struct_RtldLockState {
int lockstate;
jmp_buf env;
};
/*
* The pack of arguments and results for the symbol lookup functions.
*/
typedef struct Struct_SymLook {
const char *name;
unsigned long hash;
const Ver_Entry *ventry;
int flags;
const Obj_Entry *defobj_out;
const Elf_Sym *sym_out;
struct Struct_RtldLockState *lockstate;
} SymLook;
extern void _rtld_error(const char *, ...) __printflike(1, 2);
extern Obj_Entry *map_object(int, const char *, const struct stat *);
extern void *xcalloc(size_t);
extern void *xmalloc(size_t);
extern char *xstrdup(const char *);
extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
extern Elf_Sym sym_zero; /* For resolving undefined weak refs. */
extern void dump_relocations (Obj_Entry *);
extern void dump_obj_relocations (Obj_Entry *);
extern void dump_Elf_Rel (Obj_Entry *, const Elf_Rel *, u_long);
extern void dump_Elf_Rela (Obj_Entry *, const Elf_Rela *, u_long);
/*
* Function declarations.
*/
unsigned long elf_hash(const char *);
const Elf_Sym *find_symdef(unsigned long, const Obj_Entry *,
const Obj_Entry **, int, SymCache *, struct Struct_RtldLockState *);
void init_pltgot(Obj_Entry *);
void lockdflt_init(void);
void obj_free(Obj_Entry *);
Obj_Entry *obj_new(void);
void _rtld_bind_start(void);
void symlook_init(SymLook *, const char *);
int symlook_obj(SymLook *, const Obj_Entry *);
void *tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset);
void *allocate_tls(Obj_Entry *, void *, size_t, size_t);
void free_tls(void *, size_t, size_t);
void *allocate_module_tls(int index);
bool allocate_tls_offset(Obj_Entry *obj);
void free_tls_offset(Obj_Entry *obj);
const Ver_Entry *fetch_ventry(const Obj_Entry *obj, unsigned long);
/*
* MD function declarations.
*/
int do_copy_relocations(Obj_Entry *);
int reloc_non_plt(Obj_Entry *, Obj_Entry *, struct Struct_RtldLockState *);
int reloc_plt(Obj_Entry *);
int reloc_jmpslots(Obj_Entry *, struct Struct_RtldLockState *);
void allocate_initial_tls(Obj_Entry *);
#endif /* } */