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;