From 653ee3a7077b124368e2aeb4fc8d2ffed0de3244 Mon Sep 17 00:00:00 2001
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From: Florian Weimer <fweimer@redhat.com>
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Date: Tue, 12 Feb 2019 13:36:56 +0100
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Subject: [PATCH 11/19] elf: Ignore LD_AUDIT interfaces if la_version returns 0
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[BZ #24122]
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This change moves the audit module loading and early notification into
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separate functions out of dl_main.
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It restores the bug fix from commit
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8e889c5da3c5981c5a46a93fec02de40131ac5a6 ("elf: Fix LD_AUDIT for
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modules with invalid version (BZ#24122)") which was reverted in commit
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83e6b59625f45db1eee93e5684091f740c52a083 ("[elf] Revert 8e889c5da3
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(BZ#24122)").
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The actual bug fix is the separate error message for the case when
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la_version returns zero. The dynamic linker error message (which is
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NULL in this case) is no longer used. Based on the intended use of
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version zero (ignore this module due to explicit request), the message
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is only printed if debugging is enabled.
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(cherry picked from commit 3b856d093f5197637a5927c37d6c07dad8c86d45)
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Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
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---
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elf/rtld.c | 362 +++++++++++++++++++++++++++++------------------------
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1 file changed, 200 insertions(+), 162 deletions(-)
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diff --git a/elf/rtld.c b/elf/rtld.c
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index 5d97f41b..1524328f 100644
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--- a/elf/rtld.c
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+++ b/elf/rtld.c
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@@ -863,6 +863,205 @@ handle_ld_preload (const char *preloadlist, struct link_map *main_map)
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return npreloads;
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}
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+/* Called if the audit DSO cannot be used: if it does not have the
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+ appropriate interfaces, or it expects a more recent version library
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+ version than what the dynamic linker provides. */
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+static void
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+unload_audit_module (struct link_map *map, int original_tls_idx)
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+{
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+#ifndef NDEBUG
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+ Lmid_t ns = map->l_ns;
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+#endif
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+ _dl_close (map);
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+
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+ /* Make sure the namespace has been cleared entirely. */
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+ assert (GL(dl_ns)[ns]._ns_loaded == NULL);
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+ assert (GL(dl_ns)[ns]._ns_nloaded == 0);
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+
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+ GL(dl_tls_max_dtv_idx) = original_tls_idx;
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+}
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+
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+/* Called to print an error message if loading of an audit module
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+ failed. */
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+static void
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+report_audit_module_load_error (const char *name, const char *err_str,
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+ bool malloced)
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+{
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+ _dl_error_printf ("\
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+ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
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+ name, err_str);
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+ if (malloced)
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+ free ((char *) err_str);
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+}
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+
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+/* Load one audit module. */
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+static void
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+load_audit_module (const char *name, struct audit_ifaces **last_audit)
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+{
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+ int original_tls_idx = GL(dl_tls_max_dtv_idx);
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+
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+ struct dlmopen_args dlmargs;
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+ dlmargs.fname = name;
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+ dlmargs.map = NULL;
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+
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+ const char *objname;
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+ const char *err_str = NULL;
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+ bool malloced;
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+ _dl_catch_error (&objname, &err_str, &malloced, dlmopen_doit, &dlmargs);
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+ if (__glibc_unlikely (err_str != NULL))
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+ {
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+ report_audit_module_load_error (name, err_str, malloced);
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+ return;
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+ }
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+
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+ struct lookup_args largs;
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+ largs.name = "la_version";
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+ largs.map = dlmargs.map;
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+ _dl_catch_error (&objname, &err_str, &malloced, lookup_doit, &largs);
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+ if (__glibc_likely (err_str != NULL))
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+ {
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+ unload_audit_module (dlmargs.map, original_tls_idx);
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+ report_audit_module_load_error (name, err_str, malloced);
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+ return;
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+ }
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+
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+ unsigned int (*laversion) (unsigned int) = largs.result;
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+
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+ /* A null symbol indicates that something is very wrong with the
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+ loaded object because defined symbols are supposed to have a
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+ valid, non-null address. */
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+ assert (laversion != NULL);
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+
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+ unsigned int lav = laversion (LAV_CURRENT);
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+ if (lav == 0)
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+ {
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+ /* Only print an error message if debugging because this can
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+ happen deliberately. */
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+ if (GLRO(dl_debug_mask) & DL_DEBUG_FILES)
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+ _dl_debug_printf ("\
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+file=%s [%lu]; audit interface function la_version returned zero; ignored.\n",
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+ dlmargs.map->l_name, dlmargs.map->l_ns);
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+ unload_audit_module (dlmargs.map, original_tls_idx);
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+ return;
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+ }
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+
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+ if (lav > LAV_CURRENT)
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+ {
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+ _dl_debug_printf ("\
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+ERROR: audit interface '%s' requires version %d (maximum supported version %d); ignored.\n",
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+ name, lav, LAV_CURRENT);
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+ unload_audit_module (dlmargs.map, original_tls_idx);
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+ return;
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+ }
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+
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+ enum { naudit_ifaces = 8 };
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+ union
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+ {
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+ struct audit_ifaces ifaces;
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+ void (*fptr[naudit_ifaces]) (void);
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+ } *newp = malloc (sizeof (*newp));
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+ if (newp == NULL)
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+ _dl_fatal_printf ("Out of memory while loading audit modules\n");
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+
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+ /* Names of the auditing interfaces. All in one
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+ long string. */
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+ static const char audit_iface_names[] =
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+ "la_activity\0"
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+ "la_objsearch\0"
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+ "la_objopen\0"
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+ "la_preinit\0"
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+#if __ELF_NATIVE_CLASS == 32
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+ "la_symbind32\0"
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+#elif __ELF_NATIVE_CLASS == 64
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+ "la_symbind64\0"
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+#else
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+# error "__ELF_NATIVE_CLASS must be defined"
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+#endif
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+#define STRING(s) __STRING (s)
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+ "la_" STRING (ARCH_LA_PLTENTER) "\0"
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+ "la_" STRING (ARCH_LA_PLTEXIT) "\0"
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+ "la_objclose\0";
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+ unsigned int cnt = 0;
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+ const char *cp = audit_iface_names;
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+ do
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+ {
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+ largs.name = cp;
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+ _dl_catch_error (&objname, &err_str, &malloced, lookup_doit, &largs);
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+
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+ /* Store the pointer. */
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+ if (err_str == NULL && largs.result != NULL)
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+ {
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+ newp->fptr[cnt] = largs.result;
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+
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+ /* The dynamic linker link map is statically allocated,
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+ initialize the data now. */
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+ GL(dl_rtld_map).l_audit[cnt].cookie = (intptr_t) &GL(dl_rtld_map);
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+ }
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+ else
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+ newp->fptr[cnt] = NULL;
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+ ++cnt;
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+
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+ cp = rawmemchr (cp, '\0') + 1;
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+ }
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+ while (*cp != '\0');
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+ assert (cnt == naudit_ifaces);
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+
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+ /* Now append the new auditing interface to the list. */
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+ newp->ifaces.next = NULL;
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+ if (*last_audit == NULL)
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+ *last_audit = GLRO(dl_audit) = &newp->ifaces;
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+ else
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+ *last_audit = (*last_audit)->next = &newp->ifaces;
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+ ++GLRO(dl_naudit);
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+
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+ /* Mark the DSO as being used for auditing. */
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+ dlmargs.map->l_auditing = 1;
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+}
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+
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+/* Notify the the audit modules that the object MAP has already been
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+ loaded. */
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+static void
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+notify_audit_modules_of_loaded_object (struct link_map *map)
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+{
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+ struct audit_ifaces *afct = GLRO(dl_audit);
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+ for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
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+ {
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+ if (afct->objopen != NULL)
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+ {
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+ map->l_audit[cnt].bindflags
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+ = afct->objopen (map, LM_ID_BASE, &map->l_audit[cnt].cookie);
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+ map->l_audit_any_plt |= map->l_audit[cnt].bindflags != 0;
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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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+
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+/* Load all audit modules. */
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+static void
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+load_audit_modules (struct link_map *main_map)
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+{
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+ struct audit_ifaces *last_audit = NULL;
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+ struct audit_list_iter al_iter;
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+ audit_list_iter_init (&al_iter);
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+
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+ while (true)
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+ {
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+ const char *name = audit_list_iter_next (&al_iter);
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+ if (name == NULL)
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+ break;
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+ load_audit_module (name, &last_audit);
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+ }
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+
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+ /* Notify audit modules of the initially loaded modules (the main
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+ program and the dynamic linker itself). */
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+ if (GLRO(dl_naudit) > 0)
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+ {
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+ notify_audit_modules_of_loaded_object (main_map);
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+ notify_audit_modules_of_loaded_object (&GL(dl_rtld_map));
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+ }
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+}
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+
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static void
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dl_main (const ElfW(Phdr) *phdr,
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ElfW(Word) phnum,
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@@ -1395,10 +1594,6 @@ ERROR: '%s': cannot process note segment.\n", _dl_argv[0]);
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if (__glibc_unlikely (audit_list != NULL)
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|| __glibc_unlikely (audit_list_string != NULL))
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{
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- struct audit_ifaces *last_audit = NULL;
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- struct audit_list_iter al_iter;
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- audit_list_iter_init (&al_iter);
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-
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/* Since we start using the auditing DSOs right away we need to
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initialize the data structures now. */
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tcbp = init_tls ();
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@@ -1410,164 +1605,7 @@ ERROR: '%s': cannot process note segment.\n", _dl_argv[0]);
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security_init ();
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need_security_init = false;
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- while (true)
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- {
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- const char *name = audit_list_iter_next (&al_iter);
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- if (name == NULL)
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- break;
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-
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- int tls_idx = GL(dl_tls_max_dtv_idx);
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-
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- /* Now it is time to determine the layout of the static TLS
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- block and allocate it for the initial thread. Note that we
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- always allocate the static block, we never defer it even if
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- no DF_STATIC_TLS bit is set. The reason is that we know
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- glibc will use the static model. */
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- struct dlmopen_args dlmargs;
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- dlmargs.fname = name;
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- dlmargs.map = NULL;
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-
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- const char *objname;
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- const char *err_str = NULL;
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- bool malloced;
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- (void) _dl_catch_error (&objname, &err_str, &malloced, dlmopen_doit,
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- &dlmargs);
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- if (__glibc_unlikely (err_str != NULL))
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- {
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- not_loaded:
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- _dl_error_printf ("\
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-ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
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- name, err_str);
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- if (malloced)
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- free ((char *) err_str);
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- }
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- else
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- {
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- struct lookup_args largs;
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- largs.name = "la_version";
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- largs.map = dlmargs.map;
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-
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- /* Check whether the interface version matches. */
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- (void) _dl_catch_error (&objname, &err_str, &malloced,
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- lookup_doit, &largs);
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-
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- unsigned int (*laversion) (unsigned int);
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- unsigned int lav;
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- if (err_str == NULL
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- && (laversion = largs.result) != NULL
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- && (lav = laversion (LAV_CURRENT)) > 0
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- && lav <= LAV_CURRENT)
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- {
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- /* Allocate structure for the callback function pointers.
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- This call can never fail. */
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- union
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- {
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- struct audit_ifaces ifaces;
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-#define naudit_ifaces 8
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- void (*fptr[naudit_ifaces]) (void);
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- } *newp = malloc (sizeof (*newp));
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-
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- /* Names of the auditing interfaces. All in one
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- long string. */
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- static const char audit_iface_names[] =
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- "la_activity\0"
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- "la_objsearch\0"
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- "la_objopen\0"
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- "la_preinit\0"
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-#if __ELF_NATIVE_CLASS == 32
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- "la_symbind32\0"
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-#elif __ELF_NATIVE_CLASS == 64
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- "la_symbind64\0"
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-#else
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-# error "__ELF_NATIVE_CLASS must be defined"
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-#endif
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-#define STRING(s) __STRING (s)
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- "la_" STRING (ARCH_LA_PLTENTER) "\0"
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- "la_" STRING (ARCH_LA_PLTEXIT) "\0"
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- "la_objclose\0";
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- unsigned int cnt = 0;
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- const char *cp = audit_iface_names;
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- do
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- {
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- largs.name = cp;
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- (void) _dl_catch_error (&objname, &err_str, &malloced,
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- lookup_doit, &largs);
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-
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- /* Store the pointer. */
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- if (err_str == NULL && largs.result != NULL)
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- {
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- newp->fptr[cnt] = largs.result;
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-
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- /* The dynamic linker link map is statically
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- allocated, initialize the data now. */
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- GL(dl_rtld_map).l_audit[cnt].cookie
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- = (intptr_t) &GL(dl_rtld_map);
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- }
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- else
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- newp->fptr[cnt] = NULL;
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- ++cnt;
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-
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- cp = (char *) rawmemchr (cp, '\0') + 1;
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- }
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- while (*cp != '\0');
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- assert (cnt == naudit_ifaces);
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-
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- /* Now append the new auditing interface to the list. */
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- newp->ifaces.next = NULL;
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- if (last_audit == NULL)
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- last_audit = GLRO(dl_audit) = &newp->ifaces;
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- else
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- last_audit = last_audit->next = &newp->ifaces;
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- ++GLRO(dl_naudit);
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-
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- /* Mark the DSO as being used for auditing. */
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- dlmargs.map->l_auditing = 1;
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- }
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- else
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- {
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- /* We cannot use the DSO, it does not have the
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- appropriate interfaces or it expects something
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- more recent. */
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-#ifndef NDEBUG
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- Lmid_t ns = dlmargs.map->l_ns;
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-#endif
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- _dl_close (dlmargs.map);
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-
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- /* Make sure the namespace has been cleared entirely. */
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- assert (GL(dl_ns)[ns]._ns_loaded == NULL);
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- assert (GL(dl_ns)[ns]._ns_nloaded == 0);
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-
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- GL(dl_tls_max_dtv_idx) = tls_idx;
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- goto not_loaded;
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- }
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- }
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- }
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-
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- /* If we have any auditing modules, announce that we already
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- have two objects loaded. */
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- if (__glibc_unlikely (GLRO(dl_naudit) > 0))
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- {
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- struct link_map *ls[2] = { main_map, &GL(dl_rtld_map) };
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-
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- for (unsigned int outer = 0; outer < 2; ++outer)
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- {
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- struct audit_ifaces *afct = GLRO(dl_audit);
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- for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
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- {
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- if (afct->objopen != NULL)
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- {
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- ls[outer]->l_audit[cnt].bindflags
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- = afct->objopen (ls[outer], LM_ID_BASE,
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- &ls[outer]->l_audit[cnt].cookie);
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-
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- ls[outer]->l_audit_any_plt
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- |= ls[outer]->l_audit[cnt].bindflags != 0;
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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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- }
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+ load_audit_modules (main_map);
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}
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/* Keep track of the currently loaded modules to count how many
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--
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2.20.1
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