From patchwork Sat Feb 2 15:28:41 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 1035471 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=sourceware.org (client-ip=209.132.180.131; helo=sourceware.org; envelope-from=libc-alpha-return-99698-incoming=patchwork.ozlabs.org@sourceware.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; secure) header.d=sourceware.org header.i=@sourceware.org header.b="hygT8vQ+"; dkim-atps=neutral Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 43sHwQ5mg6z9sMr for ; Sun, 3 Feb 2019 02:28:54 +1100 (AEDT) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:subject:date:message-id:mime-version :content-type:content-transfer-encoding; q=dns; s=default; b=ZZQ qi+YcxNsZhO5pA7TD4KefYokRiTHUgOj8V5dKkTfINhH10J2gkmvd84Q3FNB105n 9wDlgGFvUm8k2/k13lsTYFC6BD0L7tdVc4jTxdg+P01sRdwhLscbIw1BjSoLp+ju 1n4KHJ7dlcxE+B6II6IqqTYjktic+7xU8HIfkNGc= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:subject:date:message-id:mime-version :content-type:content-transfer-encoding; s=default; bh=UIXwAOIiu Vxa/7mFWRSttzSIztU=; b=hygT8vQ+4WMbcn71fs2S7C1DU47Yji1uGId6EkSNJ 2XTR2p8fBMj7ZNr0J/6QEVnj9I8XaEOYnT+Vs+Wy78biMqnarlqo2xkdmkwk5iid LqL8ZvvP3sYoKXzg2/9HB8thUzrio53kmLQU/GjVj3XojlndBGeKbjl6AWBAHK0Y F4= Received: (qmail 19246 invoked by alias); 2 Feb 2019 15:28:48 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 19238 invoked by uid 89); 2 Feb 2019 15:28:48 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-24.9 required=5.0 tests=BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_LAZY_DOMAIN_SECURITY, SEM_URIRED, SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=announce X-HELO: mx1.redhat.com From: Florian Weimer To: libc-alpha@sourceware.org Subject: [PATCH] elf: Ignore LD_AUDIT interfaces if la_version returns 0 [BZ #24122] Date: Sat, 02 Feb 2019 16:28:41 +0100 Message-ID: <87imy2w6om.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 This is a repost of the early patch for glibc 2.30. I updated some comments, replaced one “unsigned” with “unsigned int”, and introduced the early_audit_modules_notification function. Thanks, Florian ----- This change moves the audit module loading and early notification into separate functions out of dl_main. It restores the bug fix from commit 8e889c5da3c5981c5a46a93fec02de40131ac5a6 ("elf: Fix LD_AUDIT for modules with invalid version (BZ#24122)") which was reverted in commit 83e6b59625f45db1eee93e5684091f740c52a083 ("[elf] Revert 8e889c5da3 (BZ#24122)"). The actual bug fix is the separate error message for the case when la_version is zero. The dynamic linker error message (which is NULL in this case) is no longer used. Based on the intended use of version zero (ignore this module due to explicit request), the message is only printed if debugging is enabled. 2019-02-02 Florian Weimer [BZ #24122] * elf/rtld.c (unload_audit_module): New function. (report_audit_module_load_error): Likewise. (load_audit_module): Likewise. Extracted from dl_main. Call _dl_close if the laversion symbol cannot be found. Use early returns for error handling. Check for a zero return value from la_version. Remove spurious comment about static TLS initialization. Remove (void) casts of function results. (load_audit_modules): New function. Extracted from dl_main. (early_audit_modules_notification): Likewise. (dl_main): Call load_audit_modules and early_audit_modules_notification. diff --git a/elf/rtld.c b/elf/rtld.c index 5d97f41b7b..3babe0185b 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -863,6 +863,205 @@ handle_ld_preload (const char *preloadlist, struct link_map *main_map) return npreloads; } +/* Called if the audit DSO cannot be used: if it does not have the + appropriate interfaces, or it expects a more recent version library + version than what the dynamic linker provides. */ +static void +unload_audit_module (struct link_map *map, int original_tls_idx) +{ +#ifndef NDEBUG + Lmid_t ns = map->l_ns; +#endif + _dl_close (map); + + /* Make sure the namespace has been cleared entirely. */ + assert (GL(dl_ns)[ns]._ns_loaded == NULL); + assert (GL(dl_ns)[ns]._ns_nloaded == 0); + + GL(dl_tls_max_dtv_idx) = original_tls_idx; +} + +/* Called to print an error message if loading of an audit module + failed. */ +static void +report_audit_module_load_error (const char *name, const char *err_str, + bool malloced) +{ + _dl_error_printf ("\ +ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n", + name, err_str); + if (malloced) + free ((char *) err_str); +} + +/* Load one audit module. */ +static void +load_audit_module (const char *name, struct audit_ifaces **last_audit) +{ + int original_tls_idx = GL(dl_tls_max_dtv_idx); + + struct dlmopen_args dlmargs; + dlmargs.fname = name; + dlmargs.map = NULL; + + const char *objname; + const char *err_str = NULL; + bool malloced; + _dl_catch_error (&objname, &err_str, &malloced, dlmopen_doit, &dlmargs); + if (__glibc_unlikely (err_str != NULL)) + { + report_audit_module_load_error (name, err_str, malloced); + return; + } + + struct lookup_args largs; + largs.name = "la_version"; + largs.map = dlmargs.map; + _dl_catch_error (&objname, &err_str, &malloced, lookup_doit, &largs); + if (__glibc_likely (err_str != NULL)) + { + unload_audit_module (dlmargs.map, original_tls_idx); + report_audit_module_load_error (name, err_str, malloced); + return; + } + + unsigned int (*laversion) (unsigned int) = largs.result; + assert (laversion != NULL); + unsigned int lav = laversion (LAV_CURRENT); + if (lav == 0) + { + /* Only print an error message if debugging because this can + happen deliberately. */ + if (GLRO(dl_debug_mask) & DL_DEBUG_FILES) + _dl_debug_printf ("\ +file=%s [%lu]; audit interface function la_version returned zero; ignored.\n", + dlmargs.map->l_name, dlmargs.map->l_ns); + unload_audit_module (dlmargs.map, original_tls_idx); + return; + } + + if (lav > LAV_CURRENT) + { + _dl_debug_printf ("\ +ERROR: audit interface '%s' requires version %d (maximum supported version %d); ignored.\n", + name, lav, LAV_CURRENT); + unload_audit_module (dlmargs.map, original_tls_idx); + return; + } + + /* Allocate structure for the callback function pointers. This call + can never fail. */ + enum { naudit_ifaces = 8 }; + union + { + struct audit_ifaces ifaces; + void (*fptr[naudit_ifaces]) (void); + } *newp = malloc (sizeof (*newp)); + + /* Names of the auditing interfaces. All in one + long string. */ + static const char audit_iface_names[] = + "la_activity\0" + "la_objsearch\0" + "la_objopen\0" + "la_preinit\0" +#if __ELF_NATIVE_CLASS == 32 + "la_symbind32\0" +#elif __ELF_NATIVE_CLASS == 64 + "la_symbind64\0" +#else +# error "__ELF_NATIVE_CLASS must be defined" +#endif +#define STRING(s) __STRING (s) + "la_" STRING (ARCH_LA_PLTENTER) "\0" + "la_" STRING (ARCH_LA_PLTEXIT) "\0" + "la_objclose\0"; + unsigned int cnt = 0; + const char *cp = audit_iface_names; + do + { + largs.name = cp; + (void) _dl_catch_error (&objname, &err_str, &malloced, + lookup_doit, &largs); + + /* Store the pointer. */ + if (err_str == NULL && largs.result != NULL) + { + newp->fptr[cnt] = largs.result; + + /* The dynamic linker link map is statically allocated, + initialize the data now. */ + GL(dl_rtld_map).l_audit[cnt].cookie + = (intptr_t) &GL(dl_rtld_map); + } + else + newp->fptr[cnt] = NULL; + ++cnt; + + cp = (char *) rawmemchr (cp, '\0') + 1; + } + while (*cp != '\0'); + assert (cnt == naudit_ifaces); + + /* Now append the new auditing interface to the list. */ + newp->ifaces.next = NULL; + if (*last_audit == NULL) + *last_audit = GLRO(dl_audit) = &newp->ifaces; + else + *last_audit = (*last_audit)->next = &newp->ifaces; + ++GLRO(dl_naudit); + + /* Mark the DSO as being used for auditing. */ + dlmargs.map->l_auditing = 1; +} + +/* Load all audit modules. */ +static void +load_audit_modules (void) +{ + struct audit_ifaces *last_audit = NULL; + struct audit_list_iter al_iter; + audit_list_iter_init (&al_iter); + + while (true) + { + const char *name = audit_list_iter_next (&al_iter); + if (name == NULL) + break; + load_audit_module (name, &last_audit); + } +} + +/* If we have any auditing modules, announce that we already have two + objects loaded: the main program and the dynamic linker itself. */ +static void +early_audit_modules_notification (struct link_map *main_map) +{ + if (__glibc_likely (GLRO(dl_naudit) == 0)) + return; + + struct link_map *ls[2] = { main_map, &GL(dl_rtld_map) }; + + for (unsigned int outer = 0; outer < 2; ++outer) + { + struct audit_ifaces *afct = GLRO(dl_audit); + for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) + { + if (afct->objopen != NULL) + { + ls[outer]->l_audit[cnt].bindflags + = afct->objopen (ls[outer], LM_ID_BASE, + &ls[outer]->l_audit[cnt].cookie); + + ls[outer]->l_audit_any_plt + |= ls[outer]->l_audit[cnt].bindflags != 0; + } + + afct = afct->next; + } + } +} + static void dl_main (const ElfW(Phdr) *phdr, ElfW(Word) phnum, @@ -1395,10 +1594,6 @@ ERROR: '%s': cannot process note segment.\n", _dl_argv[0]); if (__glibc_unlikely (audit_list != NULL) || __glibc_unlikely (audit_list_string != NULL)) { - struct audit_ifaces *last_audit = NULL; - struct audit_list_iter al_iter; - audit_list_iter_init (&al_iter); - /* Since we start using the auditing DSOs right away we need to initialize the data structures now. */ tcbp = init_tls (); @@ -1410,164 +1605,8 @@ ERROR: '%s': cannot process note segment.\n", _dl_argv[0]); security_init (); need_security_init = false; - while (true) - { - const char *name = audit_list_iter_next (&al_iter); - if (name == NULL) - break; - - int tls_idx = GL(dl_tls_max_dtv_idx); - - /* Now it is time to determine the layout of the static TLS - block and allocate it for the initial thread. Note that we - always allocate the static block, we never defer it even if - no DF_STATIC_TLS bit is set. The reason is that we know - glibc will use the static model. */ - struct dlmopen_args dlmargs; - dlmargs.fname = name; - dlmargs.map = NULL; - - const char *objname; - const char *err_str = NULL; - bool malloced; - (void) _dl_catch_error (&objname, &err_str, &malloced, dlmopen_doit, - &dlmargs); - if (__glibc_unlikely (err_str != NULL)) - { - not_loaded: - _dl_error_printf ("\ -ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n", - name, err_str); - if (malloced) - free ((char *) err_str); - } - else - { - struct lookup_args largs; - largs.name = "la_version"; - largs.map = dlmargs.map; - - /* Check whether the interface version matches. */ - (void) _dl_catch_error (&objname, &err_str, &malloced, - lookup_doit, &largs); - - unsigned int (*laversion) (unsigned int); - unsigned int lav; - if (err_str == NULL - && (laversion = largs.result) != NULL - && (lav = laversion (LAV_CURRENT)) > 0 - && lav <= LAV_CURRENT) - { - /* Allocate structure for the callback function pointers. - This call can never fail. */ - union - { - struct audit_ifaces ifaces; -#define naudit_ifaces 8 - void (*fptr[naudit_ifaces]) (void); - } *newp = malloc (sizeof (*newp)); - - /* Names of the auditing interfaces. All in one - long string. */ - static const char audit_iface_names[] = - "la_activity\0" - "la_objsearch\0" - "la_objopen\0" - "la_preinit\0" -#if __ELF_NATIVE_CLASS == 32 - "la_symbind32\0" -#elif __ELF_NATIVE_CLASS == 64 - "la_symbind64\0" -#else -# error "__ELF_NATIVE_CLASS must be defined" -#endif -#define STRING(s) __STRING (s) - "la_" STRING (ARCH_LA_PLTENTER) "\0" - "la_" STRING (ARCH_LA_PLTEXIT) "\0" - "la_objclose\0"; - unsigned int cnt = 0; - const char *cp = audit_iface_names; - do - { - largs.name = cp; - (void) _dl_catch_error (&objname, &err_str, &malloced, - lookup_doit, &largs); - - /* Store the pointer. */ - if (err_str == NULL && largs.result != NULL) - { - newp->fptr[cnt] = largs.result; - - /* The dynamic linker link map is statically - allocated, initialize the data now. */ - GL(dl_rtld_map).l_audit[cnt].cookie - = (intptr_t) &GL(dl_rtld_map); - } - else - newp->fptr[cnt] = NULL; - ++cnt; - - cp = (char *) rawmemchr (cp, '\0') + 1; - } - while (*cp != '\0'); - assert (cnt == naudit_ifaces); - - /* Now append the new auditing interface to the list. */ - newp->ifaces.next = NULL; - if (last_audit == NULL) - last_audit = GLRO(dl_audit) = &newp->ifaces; - else - last_audit = last_audit->next = &newp->ifaces; - ++GLRO(dl_naudit); - - /* Mark the DSO as being used for auditing. */ - dlmargs.map->l_auditing = 1; - } - else - { - /* We cannot use the DSO, it does not have the - appropriate interfaces or it expects something - more recent. */ -#ifndef NDEBUG - Lmid_t ns = dlmargs.map->l_ns; -#endif - _dl_close (dlmargs.map); - - /* Make sure the namespace has been cleared entirely. */ - assert (GL(dl_ns)[ns]._ns_loaded == NULL); - assert (GL(dl_ns)[ns]._ns_nloaded == 0); - - GL(dl_tls_max_dtv_idx) = tls_idx; - goto not_loaded; - } - } - } - - /* If we have any auditing modules, announce that we already - have two objects loaded. */ - if (__glibc_unlikely (GLRO(dl_naudit) > 0)) - { - struct link_map *ls[2] = { main_map, &GL(dl_rtld_map) }; - - for (unsigned int outer = 0; outer < 2; ++outer) - { - struct audit_ifaces *afct = GLRO(dl_audit); - for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) - { - if (afct->objopen != NULL) - { - ls[outer]->l_audit[cnt].bindflags - = afct->objopen (ls[outer], LM_ID_BASE, - &ls[outer]->l_audit[cnt].cookie); - - ls[outer]->l_audit_any_plt - |= ls[outer]->l_audit[cnt].bindflags != 0; - } - - afct = afct->next; - } - } - } + load_audit_modules (); + early_audit_modules_notification (main_map); } /* Keep track of the currently loaded modules to count how many