commit c76147afe917ef7d309ee893f8f017a3c2934aac
Author: Florian Weimer <fweimer@redhat.com>
Date: Sat Feb 8 15:00:28 2020 +0100
elf: Extract _dl_sym_post, _dl_sym_find_caller_map from elf/dl-sym.c
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>
diff --git a/elf/dl-sym-post.h b/elf/dl-sym-post.h
new file mode 100644
index 0000000000000000..4c4f574633497789
--- /dev/null
+++ b/elf/dl-sym-post.h
@@ -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;
+}
diff --git a/elf/dl-sym.c b/elf/dl-sym.c
index b133850a3c6657a4..5698fd7874a0ce48 100644
--- a/elf/dl-sym.c
+++ b/elf/dl-sym.c
@@ -28,6 +28,7 @@
#include <sysdep-cancel.h>
#include <dl-tls.h>
#include <dl-irel.h>
+#include <dl-sym-post.h>
#ifdef SHARED
@@ -80,19 +81,6 @@ call_dl_lookup (void *ptr)
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 *
do_sym (void *handle, const char *name, void *who,
struct r_found_version *vers, int flags)
@@ -106,7 +94,7 @@ do_sym (void *handle, const char *name, void *who,
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
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)
{
- 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))
{
@@ -179,73 +167,7 @@ RTLD_NEXT used in code not dynamically loaded"));
#endif
value = DL_SYMBOL_ADDRESS (result, ref);
- /* 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 = 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 _dl_sym_post (result, ref, value, caller, match);
}
return NULL;