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c76147afe9
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>
107 lines
4.1 KiB
C
107 lines
4.1 KiB
C
/* 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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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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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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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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/* 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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/* 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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#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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if (match == NULL)
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match = _dl_sym_find_caller_link_map (caller);
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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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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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afct = afct->next;
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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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