elf: Add _dl_audit_pltenter

It consolidates the code required to call la_pltenter audit
callback.

Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.

Reviewed-by: Florian Weimer <fweimer@redhat.com>

1 files changed, 77 insertions, 0 deletions

diff --git a/elf/dl-audit.c b/elf/dl-audit.c
index 0b6fac8e48..15250c67e8 100644
--- a/elf/dl-audit.c
+++ b/elf/dl-audit.c
@@ -17,7 +17,9 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <assert.h>
+#include <link.h>
 #include <ldsodefs.h>
+#include <dl-machine.h>
 
 void
 _dl_audit_activity_map (struct link_map *l, int action)
@@ -243,3 +245,78 @@ _dl_audit_symbind (struct link_map *l, struct reloc_result *reloc_result,
   reloc_result->flags = flags;
   *value = DL_FIXUP_ADDR_VALUE (sym.st_value);
 }
+
+void
+_dl_audit_pltenter (struct link_map *l, struct reloc_result *reloc_result,
+		    DL_FIXUP_VALUE_TYPE *value, void *regs, long int *framesize)
+{
+  /* Don't do anything if no auditor wants to intercept this call.  */
+  if (GLRO(dl_naudit) == 0
+      || (reloc_result->enterexit & LA_SYMB_NOPLTENTER))
+    return;
+
+  /* Sanity check:  DL_FIXUP_VALUE_CODE_ADDR (value) should have been
+     initialized earlier in this function or in another thread.  */
+  assert (DL_FIXUP_VALUE_CODE_ADDR (*value) != 0);
+  ElfW(Sym) *defsym = ((ElfW(Sym) *) D_PTR (reloc_result->bound,
+					    l_info[DT_SYMTAB])
+		       + reloc_result->boundndx);
+
+  /* Set up the sym parameter.  */
+  ElfW(Sym) sym = *defsym;
+  sym.st_value = DL_FIXUP_VALUE_ADDR (*value);
+
+  /* Get the symbol name.  */
+  const char *strtab = (const void *) D_PTR (reloc_result->bound,
+					     l_info[DT_STRTAB]);
+  const char *symname = strtab + sym.st_name;
+
+  /* Keep track of overwritten addresses.  */
+  unsigned int flags = reloc_result->flags;
+
+  struct audit_ifaces *afct = GLRO(dl_audit);
+  for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
+    {
+      if (afct->ARCH_LA_PLTENTER != NULL
+	  && (reloc_result->enterexit
+	      & (LA_SYMB_NOPLTENTER << (2 * (cnt + 1)))) == 0)
+	{
+	  long int new_framesize = -1;
+	  struct auditstate *l_state = link_map_audit_state (l, cnt);
+	  struct auditstate *bound_state
+	    = link_map_audit_state (reloc_result->bound, cnt);
+	  uintptr_t new_value
+	    = afct->ARCH_LA_PLTENTER (&sym, reloc_result->boundndx,
+				      &l_state->cookie, &bound_state->cookie,
+				      regs, &flags, symname, &new_framesize);
+	  if (new_value != (uintptr_t) sym.st_value)
+	    {
+	      flags |= LA_SYMB_ALTVALUE;
+	      sym.st_value = new_value;
+	    }
+
+	  /* Remember the results for every audit library and store a summary
+	     in the first two bits.  */
+	  reloc_result->enterexit |= ((flags & (LA_SYMB_NOPLTENTER
+						| LA_SYMB_NOPLTEXIT))
+				      << (2 * (cnt + 1)));
+
+	  if ((reloc_result->enterexit & (LA_SYMB_NOPLTEXIT
+					  << (2 * (cnt + 1))))
+	      == 0 && new_framesize != -1 && *framesize != -2)
+	    {
+	      /* If this is the first call providing information, use it.  */
+	      if (*framesize == -1)
+		*framesize = new_framesize;
+	      /* If two pltenter calls provide conflicting information, use
+		 the larger value.  */
+	      else if (new_framesize != *framesize)
+		*framesize = MAX (new_framesize, *framesize);
+	    }
+	}
+
+      afct = afct->next;
+    }
+
+  *value = DL_FIXUP_ADDR_VALUE (sym.st_value);
+}