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249 lines
8.4 KiB
249 lines
8.4 KiB
2 years ago
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commit c76147afe917ef7d309ee893f8f017a3c2934aac
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Sat Feb 8 15:00:28 2020 +0100
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elf: Extract _dl_sym_post, _dl_sym_find_caller_map from elf/dl-sym.c
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The definitions are moved into a new file, elf/dl-sym-post.h, so that
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this code can be used by the dynamic loader as well.
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Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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diff --git a/elf/dl-sym-post.h b/elf/dl-sym-post.h
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new file mode 100644
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index 0000000000000000..4c4f574633497789
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--- /dev/null
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+++ b/elf/dl-sym-post.h
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@@ -0,0 +1,106 @@
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+/* Post-processing of a symbol produced by dlsym, dlvsym.
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+ Copyright (C) 1999-2020 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+
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+/* Return the link map containing the caller address. */
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+static struct link_map *
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+_dl_sym_find_caller_link_map (ElfW(Addr) caller)
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+{
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+ struct link_map *l = _dl_find_dso_for_object (caller);
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+ if (l != NULL)
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+ return l;
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+ else
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+ /* If the address is not recognized the call comes from the main
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+ program (we hope). */
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+ return GL(dl_ns)[LM_ID_BASE]._ns_loaded;
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+}
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+
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+/* Translates RESULT, *REF, VALUE into a symbol address from the point
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+ of view of MATCH. Performs IFUNC resolution and auditing if
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+ necessary. If MATCH is NULL, CALLER is used to determine it. */
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+static void *
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+_dl_sym_post (lookup_t result, const ElfW(Sym) *ref, void *value,
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+ ElfW(Addr) caller, struct link_map *match)
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+{
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+ /* Resolve indirect function address. */
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+ if (__glibc_unlikely (ELFW(ST_TYPE) (ref->st_info) == STT_GNU_IFUNC))
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+ {
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+ DL_FIXUP_VALUE_TYPE fixup
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+ = DL_FIXUP_MAKE_VALUE (result, (ElfW(Addr)) value);
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+ fixup = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (fixup));
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+ value = (void *) DL_FIXUP_VALUE_CODE_ADDR (fixup);
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+ }
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+
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+#ifdef SHARED
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+ /* Auditing checkpoint: we have a new binding. Provide the
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+ auditing libraries the possibility to change the value and
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+ tell us whether further auditing is wanted. */
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+ if (__glibc_unlikely (GLRO(dl_naudit) > 0))
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+ {
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+ const char *strtab = (const char *) D_PTR (result,
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+ l_info[DT_STRTAB]);
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+ /* Compute index of the symbol entry in the symbol table of
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+ the DSO with the definition. */
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+ unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result,
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+ l_info[DT_SYMTAB]));
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+
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+ if (match == NULL)
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+ match = _dl_sym_find_caller_link_map (caller);
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+
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+ if ((match->l_audit_any_plt | result->l_audit_any_plt) != 0)
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+ {
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+ unsigned int altvalue = 0;
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+ struct audit_ifaces *afct = GLRO(dl_audit);
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+ /* Synthesize a symbol record where the st_value field is
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+ the result. */
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+ ElfW(Sym) sym = *ref;
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+ sym.st_value = (ElfW(Addr)) value;
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+
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+ for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
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+ {
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+ struct auditstate *match_audit
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+ = link_map_audit_state (match, cnt);
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+ struct auditstate *result_audit
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+ = link_map_audit_state (result, cnt);
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+ if (afct->symbind != NULL
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+ && ((match_audit->bindflags & LA_FLG_BINDFROM) != 0
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+ || ((result_audit->bindflags & LA_FLG_BINDTO)
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+ != 0)))
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+ {
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+ unsigned int flags = altvalue | LA_SYMB_DLSYM;
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+ uintptr_t new_value
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+ = afct->symbind (&sym, ndx,
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+ &match_audit->cookie,
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+ &result_audit->cookie,
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+ &flags, strtab + ref->st_name);
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+ if (new_value != (uintptr_t) sym.st_value)
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+ {
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+ altvalue = LA_SYMB_ALTVALUE;
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+ sym.st_value = new_value;
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+ }
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+ }
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+
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+ afct = afct->next;
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+ }
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+
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+ value = (void *) sym.st_value;
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+ }
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+ }
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+#endif
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+ return value;
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+}
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diff --git a/elf/dl-sym.c b/elf/dl-sym.c
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index b133850a3c6657a4..5698fd7874a0ce48 100644
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--- a/elf/dl-sym.c
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+++ b/elf/dl-sym.c
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@@ -28,6 +28,7 @@
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#include <sysdep-cancel.h>
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#include <dl-tls.h>
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#include <dl-irel.h>
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+#include <dl-sym-post.h>
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#ifdef SHARED
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@@ -80,19 +81,6 @@ call_dl_lookup (void *ptr)
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args->flags, NULL);
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}
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-/* Return the link map containing the caller address. */
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-static inline struct link_map *
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-find_caller_link_map (ElfW(Addr) caller)
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-{
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- struct link_map *l = _dl_find_dso_for_object (caller);
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- if (l != NULL)
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- return l;
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- else
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- /* If the address is not recognized the call comes from the main
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- program (we hope). */
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- return GL(dl_ns)[LM_ID_BASE]._ns_loaded;
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-}
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-
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static void *
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do_sym (void *handle, const char *name, void *who,
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struct r_found_version *vers, int flags)
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@@ -106,7 +94,7 @@ do_sym (void *handle, const char *name, void *who,
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if (handle == RTLD_DEFAULT)
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{
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- match = find_caller_link_map (caller);
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+ match = _dl_sym_find_caller_link_map (caller);
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/* Search the global scope. We have the simple case where
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we look up in the scope of an object which was part of
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@@ -140,7 +128,7 @@ do_sym (void *handle, const char *name, void *who,
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}
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else if (handle == RTLD_NEXT)
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{
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- match = find_caller_link_map (caller);
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+ match = _dl_sym_find_caller_link_map (caller);
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if (__glibc_unlikely (match == GL(dl_ns)[LM_ID_BASE]._ns_loaded))
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{
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@@ -179,73 +167,7 @@ RTLD_NEXT used in code not dynamically loaded"));
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#endif
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value = DL_SYMBOL_ADDRESS (result, ref);
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- /* Resolve indirect function address. */
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- if (__glibc_unlikely (ELFW(ST_TYPE) (ref->st_info) == STT_GNU_IFUNC))
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- {
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- DL_FIXUP_VALUE_TYPE fixup
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- = DL_FIXUP_MAKE_VALUE (result, (ElfW(Addr)) value);
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- fixup = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (fixup));
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- value = (void *) DL_FIXUP_VALUE_CODE_ADDR (fixup);
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- }
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-
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-#ifdef SHARED
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- /* Auditing checkpoint: we have a new binding. Provide the
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- auditing libraries the possibility to change the value and
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- tell us whether further auditing is wanted. */
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- if (__glibc_unlikely (GLRO(dl_naudit) > 0))
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- {
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- const char *strtab = (const char *) D_PTR (result,
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- l_info[DT_STRTAB]);
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- /* Compute index of the symbol entry in the symbol table of
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- the DSO with the definition. */
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- unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result,
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- l_info[DT_SYMTAB]));
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-
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- if (match == NULL)
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- match = find_caller_link_map (caller);
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-
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- if ((match->l_audit_any_plt | result->l_audit_any_plt) != 0)
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- {
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- unsigned int altvalue = 0;
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- struct audit_ifaces *afct = GLRO(dl_audit);
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- /* Synthesize a symbol record where the st_value field is
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- the result. */
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- ElfW(Sym) sym = *ref;
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- sym.st_value = (ElfW(Addr)) value;
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-
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- for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
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- {
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- struct auditstate *match_audit
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- = link_map_audit_state (match, cnt);
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- struct auditstate *result_audit
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- = link_map_audit_state (result, cnt);
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- if (afct->symbind != NULL
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- && ((match_audit->bindflags & LA_FLG_BINDFROM) != 0
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- || ((result_audit->bindflags & LA_FLG_BINDTO)
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- != 0)))
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- {
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- unsigned int flags = altvalue | LA_SYMB_DLSYM;
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- uintptr_t new_value
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- = afct->symbind (&sym, ndx,
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- &match_audit->cookie,
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- &result_audit->cookie,
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- &flags, strtab + ref->st_name);
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- if (new_value != (uintptr_t) sym.st_value)
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- {
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- altvalue = LA_SYMB_ALTVALUE;
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- sym.st_value = new_value;
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- }
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- }
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-
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- afct = afct->next;
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- }
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-
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- value = (void *) sym.st_value;
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- }
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- }
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-#endif
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-
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- return value;
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+ return _dl_sym_post (result, ref, value, caller, match);
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}
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return NULL;
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