freebsd-dev/libexec/rtld-elf/rtld.h
Konstantin Belousov 4903c73faf Some fixes for LD_BIND_NOW + ifuncs.
- Do not perform ifunc relocations together with other PLT relocations
  in PLT.  Instead, do it during an additional pass over the init
  list, so that ifuncs are resolved in the order of dso
  dependencies. This allows the ifuncs resolvers to call into depended
  libs.  Init list now includes all objects instead of only objects
  with init/fini callables.
- Disable relro protection around bind_now ifunc relocations.

I considered calling ifunc resolvers of dso after initializers of all
dependencies are processed, and decided that this is wrong/should not
be supported. The order now is normal relocations for all
objects->ifunc resolution in init order->initializers, where each step
does complete pass over all loaded objects before moving to the next
step.

Reported, tested and reviewed by:	emaste
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D18400
2018-12-03 20:03:43 +00:00

413 lines
16 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* 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 <stdarg.h>
#include <setjmp.h>
#include <stddef.h>
#include "rtld_lock.h"
#include "rtld_machdep.h"
#define NEW(type) ((type *) xmalloc(sizeof(type)))
#define CNEW(type) ((type *) xcalloc(1, 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 Elf_Addr tls_dtv_generation;
extern int tls_max_index;
extern int npagesizes;
extern size_t *pagesizes;
extern int main_argc;
extern char **main_argv;
extern char **environ;
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);
typedef void (*InitArrFunc)(int, char **, char **);
/* 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;
typedef struct Struct_Sym_Match_Result {
const Elf_Sym *sym_out;
const Elf_Sym *vsymp;
int vcount;
} Sym_Match_Result;
#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 */
TAILQ_ENTRY(Struct_Obj_Entry) next;
char *path; /* Pathname of underlying file (%) */
char *origin_path; /* Directory path of origin file */
int refcount; /* DAG references */
int holdcount; /* Count of transient references */
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 */
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 */
Elf_Word stack_flags;
/* 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 */
caddr_t relro_page;
size_t relro_size;
/* 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 */
Elf_Addr *mips_pltgot; /* Second PLT GOT */
#endif
#ifdef __powerpc64__
Elf_Addr glink; /* GLINK PLT call stub section */
#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 entries in chain array */
Elf32_Word nbuckets_gnu; /* Number of GNU hash buckets*/
Elf32_Word symndx_gnu; /* 1st accessible symbol on dynsym table */
Elf32_Word maskwords_bm_gnu; /* Bloom filter words - 1 (bitmask) */
Elf32_Word shift2_gnu; /* Bloom filter shift count */
Elf32_Word dynsymcount; /* Total entries in dynsym table */
const Elf_Addr *bloom_gnu; /* Bloom filter used by GNU hash func */
const Elf_Hashelt *buckets_gnu; /* GNU hash table bucket array */
const Elf_Hashelt *chain_zero_gnu; /* GNU hash table value array (Zeroed) */
const char *rpath; /* Search path specified in object */
const char *runpath; /* Search path with different priority */
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 */
Elf_Addr preinit_array; /* Pre-initialization array of functions */
Elf_Addr init_array; /* Initialization array of functions */
Elf_Addr fini_array; /* Termination array of functions */
int preinit_array_num; /* Number of entries in preinit_array */
int init_array_num; /* Number of entries in init_array */
int fini_array_num; /* Number of entries in fini_array */
int32_t osrel; /* OSREL note value */
uint32_t fctl0; /* FEATURE_CONTROL note desc[0] value */
bool mainprog : 1; /* True if this is the main program */
bool rtld : 1; /* True if this is the dynamic linker */
bool relocated : 1; /* True if processed by relocate_objects() */
bool ver_checked : 1; /* True if processed by rtld_verify_object_versions */
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 z_interpose : 1; /* Interpose all objects but main */
bool z_nodeflib : 1; /* Don't search default library path */
bool z_global : 1; /* Make the object global */
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 */
bool irelative : 1; /* Object has R_MACHDEP_IRELATIVE relocs */
bool gnu_ifunc : 1; /* Object has references to STT_GNU_IFUNC */
bool non_plt_gnu_ifunc : 1; /* Object has non-plt IFUNC references */
bool ifuncs_resolved : 1; /* Object ifuncs were already resolved */
bool crt_no_init : 1; /* Object' crt does not call _init/_fini */
bool valid_hash_sysv : 1; /* A valid System V hash hash tag is available */
bool valid_hash_gnu : 1; /* A valid GNU hash tag is available */
bool dlopened : 1; /* dlopen()-ed (vs. load statically) */
bool marker : 1; /* marker on the global obj list */
bool unholdfree : 1; /* unmap upon last unhold */
bool doomed : 1; /* Object cannot be referenced */
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-dependent */
} Obj_Entry;
#define RTLD_MAGIC 0xd550b87a
#define RTLD_VERSION 1
TAILQ_HEAD(obj_entry_q, Struct_Obj_Entry);
#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 newest versioned symbol. Used by
dlsym. */
#define SYMLOOK_EARLY 0x04 /* Symlook is done during initialization. */
#define SYMLOOK_IFUNC 0x08 /* Allow IFUNC processing in
reloc_non_plt(). */
/* 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. */
#define RTLD_LO_EARLY 0x20 /* Do not call ctors, postpone it to the
initialization during the image start. */
/*
* 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;
sigjmp_buf env;
};
struct fill_search_info_args {
int request;
unsigned int flags;
struct dl_serinfo *serinfo;
struct dl_serpath *serpath;
char *strspace;
};
/*
* The pack of arguments and results for the symbol lookup functions.
*/
typedef struct Struct_SymLook {
const char *name;
unsigned long hash;
uint32_t hash_gnu;
const Ver_Entry *ventry;
int flags;
const Obj_Entry *defobj_out;
const Elf_Sym *sym_out;
struct Struct_RtldLockState *lockstate;
} SymLook;
void _rtld_error(const char *, ...) __printflike(1, 2) __exported;
void rtld_die(void) __dead2;
const char *rtld_strerror(int);
Obj_Entry *map_object(int, const char *, const struct stat *);
void *xcalloc(size_t, size_t);
void *xmalloc(size_t);
char *xstrdup(const char *);
void *malloc_aligned(size_t size, size_t align);
void free_aligned(void *ptr);
extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
extern Elf_Sym sym_zero; /* For resolving undefined weak refs. */
extern bool ld_bind_not;
void dump_relocations(Obj_Entry *);
void dump_obj_relocations(Obj_Entry *);
void dump_Elf_Rel(Obj_Entry *, const Elf_Rel *, u_long);
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 lockdflt_init(void);
void digest_notes(Obj_Entry *, Elf_Addr, Elf_Addr);
Obj_Entry *globallist_curr(const Obj_Entry *obj);
Obj_Entry *globallist_next(const Obj_Entry *obj);
void obj_free(Obj_Entry *);
Obj_Entry *obj_new(void);
void _rtld_bind_start(void);
void *rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def);
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);
int convert_prot(int elfflags);
/*
* MD function declarations.
*/
int do_copy_relocations(Obj_Entry *);
int reloc_non_plt(Obj_Entry *, Obj_Entry *, int flags,
struct Struct_RtldLockState *);
int reloc_plt(Obj_Entry *);
int reloc_jmpslots(Obj_Entry *, int flags, struct Struct_RtldLockState *);
int reloc_iresolve(Obj_Entry *, struct Struct_RtldLockState *);
int reloc_gnu_ifunc(Obj_Entry *, int flags, struct Struct_RtldLockState *);
void ifunc_init(Elf_Auxinfo[__min_size(AT_COUNT)]);
void pre_init(void);
void init_pltgot(Obj_Entry *);
void allocate_initial_tls(Obj_Entry *);
#endif /* } */