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Split the symlook_obj1 into a loop iterating over the ELF object symbol

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hash elements, and a helper matched_symbol() which match the given hash
entry and request, performing needed type and version checks.

Based on dragonflybsd support for GNU hash by John Marino <draco marino st>
Reviewed by:	kan
Tested by:	bapt
MFC after:	2 weeks
This commit is contained in:
Konstantin Belousov 2012-04-30 13:29:21 +00:00
parent f51b84bcc4
commit 34cb87ba95
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=234840
2 changed files with 116 additions and 95 deletions
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205
libexec/rtld-elf/rtld.c
View File

@ -1,7 +1,8 @@
/*-
* Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
* Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>.
* Copyright 2009, 2010, 2011 Konstantin Belousov <kib@FreeBSD.ORG>.
* Copyright 2009-2012 Konstantin Belousov <kib@FreeBSD.ORG>.
* Copyright 2012 John Marino <draco@marino.st>.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@ -149,6 +150,8 @@ static int object_match_name(const Obj_Entry *, const char *);
static void ld_utrace_log(int, void *, void *, size_t, int, const char *);
static void rtld_fill_dl_phdr_info(const Obj_Entry *obj,
struct dl_phdr_info *phdr_info);
static bool matched_symbol(SymLook *, const Obj_Entry *, Sym_Match_Result *,
const unsigned long);
void r_debug_state(struct r_debug *, struct link_map *) __noinline;
@ -3439,28 +3442,15 @@ symlook_obj(SymLook *req, const Obj_Entry *obj)
return (mres);
}
static int
symlook_obj1(SymLook *req, const Obj_Entry *obj)
/* Symbol match routine common to both hash functions */
static bool
matched_symbol(SymLook *req, const Obj_Entry *obj, Sym_Match_Result *result,
const unsigned long symnum)
{
unsigned long symnum;
const Elf_Sym *vsymp;
Elf_Versym verndx;
int vcount;
if (obj->buckets == NULL)
return (ESRCH);
vsymp = NULL;
vcount = 0;
symnum = obj->buckets[req->hash % obj->nbuckets];
for (; symnum != STN_UNDEF; symnum = obj->chains[symnum]) {
Elf_Versym verndx;
const Elf_Sym *symp;
const char *strp;
if (symnum >= obj->nchains)
return (ESRCH); /* Bad object */
symp = obj->symtab + symnum;
strp = obj->strtab + symp->st_name;
@ -3468,103 +3458,128 @@ symlook_obj1(SymLook *req, const Obj_Entry *obj)
case STT_FUNC:
case STT_NOTYPE:
case STT_OBJECT:
case STT_COMMON:
case STT_GNU_IFUNC:
if (symp->st_value == 0)
continue;
if (symp->st_value == 0)
return (false);
/* fallthrough */
case STT_TLS:
if (symp->st_shndx != SHN_UNDEF)
break;
if (symp->st_shndx != SHN_UNDEF)
break;
#ifndef __mips__
else if (((req->flags & SYMLOOK_IN_PLT) == 0) &&
(ELF_ST_TYPE(symp->st_info) == STT_FUNC))
break;
else if (((req->flags & SYMLOOK_IN_PLT) == 0) &&
(ELF_ST_TYPE(symp->st_info) == STT_FUNC))
break;
/* fallthrough */
#endif
default:
continue;
return (false);
}
if (req->name[0] != strp[0] || strcmp(req->name, strp) != 0)
continue;
return (false);
if (req->ventry == NULL) {
if (obj->versyms != NULL) {
verndx = VER_NDX(obj->versyms[symnum]);
if (verndx > obj->vernum) {
_rtld_error("%s: symbol %s references wrong version %d",
obj->path, obj->strtab + symnum, verndx);
continue;
if (obj->versyms != NULL) {
verndx = VER_NDX(obj->versyms[symnum]);
if (verndx > obj->vernum) {
_rtld_error(
"%s: symbol %s references wrong version %d",
obj->path, obj->strtab + symnum, verndx);
return (false);
}
/*
* If we are not called from dlsym (i.e. this
* is a normal relocation from unversioned
* binary), accept the symbol immediately if
* it happens to have first version after this
* shared object became versioned. Otherwise,
* if symbol is versioned and not hidden,
* remember it. If it is the only symbol with
* this name exported by the shared object, it
* will be returned as a match by the calling
* function. If symbol is global (verndx < 2)
* accept it unconditionally.
*/
if ((req->flags & SYMLOOK_DLSYM) == 0 &&
verndx == VER_NDX_GIVEN) {
result->sym_out = symp;
return (true);
}
else if (verndx >= VER_NDX_GIVEN) {
if ((obj->versyms[symnum] & VER_NDX_HIDDEN)
== 0) {
if (result->vsymp == NULL)
result->vsymp = symp;
result->vcount++;
}
return (false);
}
}
/*
* If we are not called from dlsym (i.e. this is a normal
* relocation from unversioned binary), accept the symbol
* immediately if it happens to have first version after
* this shared object became versioned. Otherwise, if
* symbol is versioned and not hidden, remember it. If it
* is the only symbol with this name exported by the
* shared object, it will be returned as a match at the
* end of the function. If symbol is global (verndx < 2)
* accept it unconditionally.
*/
if ((req->flags & SYMLOOK_DLSYM) == 0 &&
verndx == VER_NDX_GIVEN) {
req->sym_out = symp;
req->defobj_out = obj;
return (0);
}
else if (verndx >= VER_NDX_GIVEN) {
if ((obj->versyms[symnum] & VER_NDX_HIDDEN) == 0) {
if (vsymp == NULL)
vsymp = symp;
vcount ++;
}
continue;
}
}
req->sym_out = symp;
req->defobj_out = obj;
return (0);
} else {
if (obj->versyms == NULL) {
result->sym_out = symp;
return (true);
}
if (obj->versyms == NULL) {
if (object_match_name(obj, req->ventry->name)) {
_rtld_error("%s: object %s should provide version %s for "
"symbol %s", obj_rtld.path, obj->path,
req->ventry->name, obj->strtab + symnum);
continue;
_rtld_error("%s: object %s should provide version %s "
"for symbol %s", obj_rtld.path, obj->path,
req->ventry->name, obj->strtab + symnum);
return (false);
}
} else {
} else {
verndx = VER_NDX(obj->versyms[symnum]);
if (verndx > obj->vernum) {
_rtld_error("%s: symbol %s references wrong version %d",
obj->path, obj->strtab + symnum, verndx);
continue;
_rtld_error("%s: symbol %s references wrong version %d",
obj->path, obj->strtab + symnum, verndx);
return (false);
}
if (obj->vertab[verndx].hash != req->ventry->hash ||
strcmp(obj->vertab[verndx].name, req->ventry->name)) {
/*
* Version does not match. Look if this is a global symbol
* and if it is not hidden. If global symbol (verndx < 2)
* is available, use it. Do not return symbol if we are
* called by dlvsym, because dlvsym looks for a specific
* version and default one is not what dlvsym wants.
*/
if ((req->flags & SYMLOOK_DLSYM) ||
(obj->versyms[symnum] & VER_NDX_HIDDEN) ||
(verndx >= VER_NDX_GIVEN))
continue;
/*
* Version does not match. Look if this is a
* global symbol and if it is not hidden. If
* global symbol (verndx < 2) is available,
* use it. Do not return symbol if we are
* called by dlvsym, because dlvsym looks for
* a specific version and default one is not
* what dlvsym wants.
*/
if ((req->flags & SYMLOOK_DLSYM) ||
(verndx >= VER_NDX_GIVEN) ||
(obj->versyms[symnum] & VER_NDX_HIDDEN))
return (false);
}
}
req->sym_out = symp;
req->defobj_out = obj;
return (0);
}
}
if (vcount == 1) {
req->sym_out = vsymp;
req->defobj_out = obj;
return (0);
}
return (ESRCH);
result->sym_out = symp;
return (true);
}
static int
symlook_obj1(SymLook *req, const Obj_Entry *obj)
{
unsigned long symnum;
Sym_Match_Result matchres;
matchres.sym_out = NULL;
matchres.vsymp = NULL;
matchres.vcount = 0;
for (symnum = obj->buckets[req->hash % obj->nbuckets];
symnum != STN_UNDEF; symnum = obj->chains[symnum]) {
if (symnum >= obj->nchains)
return (ESRCH); /* Bad object */
if (matched_symbol(req, obj, &matchres, symnum)) {
req->sym_out = matchres.sym_out;
req->defobj_out = obj;
return (0);
}
}
if (matchres.vcount == 1) {
req->sym_out = matchres.vsymp;
req->defobj_out = obj;
return (0);
}
return (ESRCH);
}
static void

6
libexec/rtld-elf/rtld.h
View File

@ -126,6 +126,12 @@ typedef struct Struct_Ver_Entry {
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
/*