system/glibc
3
0
Fork 0
Code Issues Projects Releases Wiki Activity

elf: Extract _dl_sym_post, _dl_sym_find_caller_map from elf/dl-sym.c

Browse Source 
The definitions are moved into a new file, elf/dl-sym-post.h, so that
this code can be used by the dynamic loader as well.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Florian Weimer 2020-02-08 15:00:28 +01:00
parent abcc039d2e
commit c76147afe9
2 changed files with 110 additions and 82 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

106
elf/dl-sym-post.h Normal file
View File

@ -0,0 +1,106 @@
/* Post-processing of a symbol produced by dlsym, dlvsym.
Copyright (C) 1999-2020 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/>. */
/* Return the link map containing the caller address. */
static struct link_map *
_dl_sym_find_caller_link_map (ElfW(Addr) caller)
{
struct link_map *l = _dl_find_dso_for_object (caller);
if (l != NULL)
return l;
else
/* If the address is not recognized the call comes from the main
program (we hope). */
return GL(dl_ns)[LM_ID_BASE]._ns_loaded;
}
/* Translates RESULT, *REF, VALUE into a symbol address from the point
of view of MATCH. Performs IFUNC resolution and auditing if
necessary. If MATCH is NULL, CALLER is used to determine it. */
static void *
_dl_sym_post (lookup_t result, const ElfW(Sym) *ref, void *value,
ElfW(Addr) caller, struct link_map *match)
{
/* Resolve indirect function address. */
if (__glibc_unlikely (ELFW(ST_TYPE) (ref->st_info) == STT_GNU_IFUNC))
{
DL_FIXUP_VALUE_TYPE fixup
= DL_FIXUP_MAKE_VALUE (result, (ElfW(Addr)) value);
fixup = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (fixup));
value = (void *) DL_FIXUP_VALUE_CODE_ADDR (fixup);
}
#ifdef SHARED
/* Auditing checkpoint: we have a new binding. Provide the
auditing libraries the possibility to change the value and
tell us whether further auditing is wanted. */
if (__glibc_unlikely (GLRO(dl_naudit) > 0))
{
const char *strtab = (const char *) D_PTR (result,
l_info[DT_STRTAB]);
/* Compute index of the symbol entry in the symbol table of
the DSO with the definition. */
unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result,
l_info[DT_SYMTAB]));
if (match == NULL)
match = _dl_sym_find_caller_link_map (caller);
if ((match->l_audit_any_plt | result->l_audit_any_plt) != 0)
{
unsigned int altvalue = 0;
struct audit_ifaces *afct = GLRO(dl_audit);
/* Synthesize a symbol record where the st_value field is
the result. */
ElfW(Sym) sym = *ref;
sym.st_value = (ElfW(Addr)) value;
for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
{
struct auditstate *match_audit
= link_map_audit_state (match, cnt);
struct auditstate *result_audit
= link_map_audit_state (result, cnt);
if (afct->symbind != NULL
&& ((match_audit->bindflags & LA_FLG_BINDFROM) != 0
|| ((result_audit->bindflags & LA_FLG_BINDTO)
!= 0)))
{
unsigned int flags = altvalue | LA_SYMB_DLSYM;
uintptr_t new_value
= afct->symbind (&sym, ndx,
&match_audit->cookie,
&result_audit->cookie,
&flags, strtab + ref->st_name);
if (new_value != (uintptr_t) sym.st_value)
{
altvalue = LA_SYMB_ALTVALUE;
sym.st_value = new_value;
}
}
afct = afct->next;
}
value = (void *) sym.st_value;
}
}
#endif
return value;
}

86
elf/dl-sym.c
View File

@ -28,6 +28,7 @@
#include <sysdep-cancel.h> #include <sysdep-cancel.h>
#include <dl-tls.h> #include <dl-tls.h>
#include <dl-irel.h> #include <dl-irel.h>
#include <dl-sym-post.h>
#ifdef SHARED #ifdef SHARED
@ -80,19 +81,6 @@ call_dl_lookup (void *ptr)
args->flags, NULL); args->flags, NULL);
} }
/* Return the link map containing the caller address. */
static inline struct link_map *
find_caller_link_map (ElfW(Addr) caller)
{
struct link_map *l = _dl_find_dso_for_object (caller);
if (l != NULL)
return l;
else
/* If the address is not recognized the call comes from the main
program (we hope). */
return GL(dl_ns)[LM_ID_BASE]._ns_loaded;
}
static void * static void *
do_sym (void *handle, const char *name, void *who, do_sym (void *handle, const char *name, void *who,
struct r_found_version *vers, int flags) struct r_found_version *vers, int flags)
@ -106,7 +94,7 @@ do_sym (void *handle, const char *name, void *who,
if (handle == RTLD_DEFAULT) if (handle == RTLD_DEFAULT)
{ {
match = find_caller_link_map (caller); match = _dl_sym_find_caller_link_map (caller);
/* Search the global scope. We have the simple case where /* Search the global scope. We have the simple case where
we look up in the scope of an object which was part of we look up in the scope of an object which was part of
@ -140,7 +128,7 @@ do_sym (void *handle, const char *name, void *who,
} }
else if (handle == RTLD_NEXT) else if (handle == RTLD_NEXT)
{ {
match = find_caller_link_map (caller); match = _dl_sym_find_caller_link_map (caller);
if (__glibc_unlikely (match == GL(dl_ns)[LM_ID_BASE]._ns_loaded)) if (__glibc_unlikely (match == GL(dl_ns)[LM_ID_BASE]._ns_loaded))
{ {
@ -179,73 +167,7 @@ RTLD_NEXT used in code not dynamically loaded"));
#endif #endif
value = DL_SYMBOL_ADDRESS (result, ref); value = DL_SYMBOL_ADDRESS (result, ref);
/* Resolve indirect function address. */ return _dl_sym_post (result, ref, value, caller, match);
if (__glibc_unlikely (ELFW(ST_TYPE) (ref->st_info) == STT_GNU_IFUNC))
{
DL_FIXUP_VALUE_TYPE fixup
= DL_FIXUP_MAKE_VALUE (result, (ElfW(Addr)) value);
fixup = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (fixup));
value = (void *) DL_FIXUP_VALUE_CODE_ADDR (fixup);
}
#ifdef SHARED
/* Auditing checkpoint: we have a new binding. Provide the
auditing libraries the possibility to change the value and
tell us whether further auditing is wanted. */
if (__glibc_unlikely (GLRO(dl_naudit) > 0))
{
const char *strtab = (const char *) D_PTR (result,
l_info[DT_STRTAB]);
/* Compute index of the symbol entry in the symbol table of
the DSO with the definition. */
unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result,
l_info[DT_SYMTAB]));
if (match == NULL)
match = find_caller_link_map (caller);
if ((match->l_audit_any_plt | result->l_audit_any_plt) != 0)
{
unsigned int altvalue = 0;
struct audit_ifaces *afct = GLRO(dl_audit);
/* Synthesize a symbol record where the st_value field is
the result. */
ElfW(Sym) sym = *ref;
sym.st_value = (ElfW(Addr)) value;
for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
{
struct auditstate *match_audit
= link_map_audit_state (match, cnt);
struct auditstate *result_audit
= link_map_audit_state (result, cnt);
if (afct->symbind != NULL
&& ((match_audit->bindflags & LA_FLG_BINDFROM) != 0
|| ((result_audit->bindflags & LA_FLG_BINDTO)
!= 0)))
{
unsigned int flags = altvalue | LA_SYMB_DLSYM;
uintptr_t new_value
= afct->symbind (&sym, ndx,
&match_audit->cookie,
&result_audit->cookie,
&flags, strtab + ref->st_name);
if (new_value != (uintptr_t) sym.st_value)
{
altvalue = LA_SYMB_ALTVALUE;
sym.st_value = new_value;
}
}
afct = afct->next;
}
value = (void *) sym.st_value;
}
}
#endif
return value;
} }
return NULL; return NULL;