From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pj1-x1030.google.com (mail-pj1-x1030.google.com [IPv6:2607:f8b0:4864:20::1030]) by sourceware.org (Postfix) with ESMTPS id 426DB3858D3C for ; Thu, 16 Dec 2021 02:07:46 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 426DB3858D3C Received: by mail-pj1-x1030.google.com with SMTP id r34-20020a17090a43a500b001b0f0837ce8so992998pjg.2 for ; Wed, 15 Dec 2021 18:07:46 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=H5mt9G8YCoxxMVBvh0ukF2GGyBIKQfm/6O/xBHg+UoM=; b=4EaTbHRpWQp2CjTJS9jqDtDWFOyhPQD782sxLEbwxNqMwRHk+cavBbn9T4tbcxpMVF AD/a2jh2d6CE5+NeS5C9b+oft9+5ud6HxD24X3/choBg/bHekq1isuvNEQ3Dr4wv8mux u/xEqa6NUH5auRrvqQOI72OSlYCNrwx25hxki9ngxQLWmSdGoCn/7IzwyDYSTFNV/tiC aiVitmsL9aG2n96lM5SoXiU3Xvjpm2Fzdg2vplzJRp7VxBD36jF0d3a7knSm4EO+yF1D sfpkJ/R5gFhxu/ChdgKoH0fYJmgn0ZOik2O0Du2aM66TmQxFqiIjmFwYWZnwLIdKmCis EBFg== X-Gm-Message-State: AOAM533O2uGCF3P6EG8Zg/uz/4FCQSBx7XnzmnKlieo7aGbCPlGhBJuq uNOn3Qp9zi0ICwhgPjSr7pERaYVMv8SqVrbJyB3c6CcU X-Google-Smtp-Source: ABdhPJxKNLKOXyjVCF3N2fY0aQDcso71JveXdAy/yWpgZIFnjFcO7OS0LKqCXKsfXcH0LVSm9sNCHKpH5UYV3nU7FSM= X-Received: by 2002:a17:90b:1e0e:: with SMTP id pg14mr3186402pjb.143.1639620465244; Wed, 15 Dec 2021 18:07:45 -0800 (PST) MIME-Version: 1.0 References: <20211208152501.1483087-1-hjl.tools@gmail.com> <20211208152501.1483087-4-hjl.tools@gmail.com> <3cf3f178-b974-2968-e7f9-4d8346913652@redhat.com> In-Reply-To: <3cf3f178-b974-2968-e7f9-4d8346913652@redhat.com> From: "H.J. Lu" Date: Wed, 15 Dec 2021 18:07:09 -0800 Message-ID: Subject: Re: [PATCH v3 3/3] elf: Also try DT_RUNPATH for LD_AUDIT dlopen [BZ #28455] To: "Carlos O'Donell" Cc: GNU C Library Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-3028.0 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 16 Dec 2021 02:07:48 -0000 On Mon, Dec 13, 2021 at 2:07 PM Carlos O'Donell wrote: > > On 12/8/21 10:25, H.J. Lu wrote: > > DT_RUNPATH is only used to find the immediate dependencies of the > > executable or shared object containing the DT_RUNPATH entry. Update > > the glibc LD_AUDIT dlopen call to try the DT_RUNPATH entry of the > > executable. This partially fixes BZ #28455. > > Please post v4 split out. > > > --- > > elf/Makefile | 9 +++++++-- > > elf/dl-load.c | 15 +++++++++++++++ > > elf/tst-audit14a.c | 1 + > > 3 files changed, 23 insertions(+), 2 deletions(-) > > create mode 100644 elf/tst-audit14a.c > > > > diff --git a/elf/Makefile b/elf/Makefile > > index 4b5bdcb08e..aa6b24d790 100644 > > --- a/elf/Makefile > > +++ b/elf/Makefile > > @@ -247,10 +247,10 @@ ifneq ($(selinux-enabled),1) > > tests-execstack-yes = tst-execstack tst-execstack-needed tst-execstack-prog > > endif > > ifeq ($(have-depaudit),yes) > > -tests += tst-audit14 tst-audit15 tst-audit16 > > +tests += tst-audit14 tst-audit15 tst-audit16 tst-audit14a > > Please split one test per line and sort. Fixed. > > ifeq ($(run-built-tests),yes) > > tests-special += $(objpfx)tst-audit14-cmp.out $(objpfx)tst-audit15-cmp.out \ > > - $(objpfx)tst-audit16-cmp.out > > + $(objpfx)tst-audit16-cmp.out $(objpfx)tst-audit14a-cmp.out > > Please split one test per line and sort. Fixed. > > endif > > endif > > endif > > @@ -1521,6 +1521,8 @@ tst-auditmany-ENV = \ > > LDFLAGS-tst-audit14 = -Wl,--audit=tst-auditlogmod-1.so > > $(objpfx)tst-auditlogmod-1.so: $(libsupport) > > $(objpfx)tst-audit14.out: $(objpfx)tst-auditlogmod-1.so > > +LDFLAGS-tst-audit14a = -Wl,--audit=tst-auditlogmod-1.so,--enable-new-dtags > > +$(objpfx)tst-audit14a.out: $(objpfx)tst-auditlogmod-1.so > > OK. > > > LDFLAGS-tst-audit15 = \ > > -Wl,--audit=tst-auditlogmod-1.so,--depaudit=tst-auditlogmod-2.so > > $(objpfx)tst-auditlogmod-2.so: $(libsupport) > > @@ -1547,6 +1549,9 @@ tst-audit17-ENV = LD_AUDIT=$(objpfx)tst-auditmod17.so > > $(objpfx)tst-audit14-cmp.out: tst-audit14.exp $(objpfx)tst-audit14.out > > cmp $^ > $@; \ > > $(evaluate-test) > > +$(objpfx)tst-audit14a-cmp.out: tst-audit14.exp $(objpfx)tst-audit14a.out > > + cmp $^ > $@; \ > > + $(evaluate-test) > > OK. > > > $(objpfx)tst-audit15-cmp.out: tst-audit15.exp $(objpfx)tst-audit15.out > > cmp $^ > $@; \ > > $(evaluate-test) > > diff --git a/elf/dl-load.c b/elf/dl-load.c > > index bf8957e73c..1f424ea7c8 100644 > > --- a/elf/dl-load.c > > +++ b/elf/dl-load.c > > The preceding block is like this: > > 2146 /* When the object has the RUNPATH information we don't use any > 2147 RPATHs. */ > 2148 if (loader == NULL || loader->l_info[DT_RUNPATH] == NULL) > 2149 { > > The entire design of this block is to look into DT_RPATH specifically > under two conditions: > > (a) We don't know anything about the loading module, it is NULL, and > therefore we don't know if DT_RUNPATH was present, which if it > was present, would prevent the use of DT_RPATH. > > (b) We have a loader, and we know it doesn't have DT_RUNPATH and so > we will look for DT_RPATH. > > Your changes adds (c) to this case in which DT_RUNPATH is used, and > this seems to be logically distinct from the above two cases. > > My suggestion is that the code you are adding should be in a distinct > block *after* the above block starting around line 2189. > > We already have a block like this: > 2189 /* Look at the RUNPATH information for this binary. */ > 2190 if (fd == -1 && loader != NULL > 2191 && cache_rpath (loader, &loader->l_runpath_dirs, > 2192 DT_RUNPATH, "RUNPATH")) > 2193 fd = open_path (name, namelen, mode, > 2194 &loader->l_runpath_dirs, &realname, &fb, loader, > 2195 LA_SER_RUNPATH, &found_other_class); > > I think it is logically more correct to add to this DT_RUNPATH handling > than ato add to the DT_RPATH handling above. > > So after this block you might add: > > /* When processing the lookup we may need to additionally try DT_RUNPATH > in the executable for a glibc internal dlopen call when looking for > audit modules. */ > if (__glibc_unlikely (mode & __RTLD_AUDIT) > && fd == -1) > { > ... > } Fixed. > The hard part is that you may want to know a few things: > (a) main_map (unavailable, but computable via GL(dl_ns)[LM_ID_BASE]._ns_loaded) > (b) did_main_map (unavailable) > * This seems like an optimization because if you already looked up via > main_map and it failed, doing it twice won't help, so you can refactor > did_main_map to function scope and retain the fact that you did this > check already if you want to keep the optimization. Fixed. > Otherwise everything else is there to implement the fix. > Sent out the v4 patch. Thanks. -- H.J.