From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D1C5EC282C4 for ; Tue, 12 Feb 2019 21:02:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A7292222C0 for ; Tue, 12 Feb 2019 21:02:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727816AbfBLVCe (ORCPT ); Tue, 12 Feb 2019 16:02:34 -0500 Received: from mx1.polytechnique.org ([129.104.30.34]:50954 "EHLO mx1.polytechnique.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726788AbfBLVCe (ORCPT ); Tue, 12 Feb 2019 16:02:34 -0500 Received: from mail-ot1-f46.google.com (mail-ot1-f46.google.com [209.85.210.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ssl.polytechnique.org (Postfix) with ESMTPSA id 326AF5646D5 for ; Tue, 12 Feb 2019 22:02:30 +0100 (CET) Received: by mail-ot1-f46.google.com with SMTP id i20so253271otl.0 for ; Tue, 12 Feb 2019 13:02:30 -0800 (PST) X-Gm-Message-State: AHQUAuZAXDCuv+f1Wh/OBZjiqnFUCUphtQN9AkZaYxjy9n2tCxxg19G0 BENTuDGWRucrY6hk1cqv8LqSiAWwv7TxsQUcYQ8= X-Google-Smtp-Source: AHgI3IYYYf7/5wRBM5s4Iy6jzJjUiQ4xQ6dIYoh7/2ukmLC/cPlI+vjplkbWq2O0ExXGAXoJMOOgdWVrtzMNq69a4yY= X-Received: by 2002:a9d:6206:: with SMTP id g6mr5808580otj.338.1550005349298; Tue, 12 Feb 2019 13:02:29 -0800 (PST) MIME-Version: 1.0 References: <20190212152046.13875-1-plautrba@redhat.com> In-Reply-To: <20190212152046.13875-1-plautrba@redhat.com> From: Nicolas Iooss Date: Tue, 12 Feb 2019 22:02:18 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2] libsemanage: genhomedircon - improve handling large groups To: Petr Lautrbach Cc: selinux@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-AV-Checked: ClamAV using ClamSMTP at svoboda.polytechnique.org (Tue Feb 12 22:02:30 2019 +0100 (CET)) X-Org-Mail: nicolas.iooss.2010@polytechnique.org Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org On Tue, Feb 12, 2019 at 4:20 PM Petr Lautrbach wrote: > > getgrnam_r() uses a preallocated buffer to store a structure containing > the broken-out fields of the record in the group database. The size of > this buffer is usually sysconf(_SC_GETGR_R_SIZE_MAX) == 1024 and it is > not enough for groups with a large number of users. In these cases, > getgrnam_r() returns -1 and sets errno to ERANGE and the caller can > retry with a larger buffer. > > Fixes: > $ semanage login -a -s user_u -r s0-s0:c1.c2 '%largegroup' > libsemanage.semanage_direct_commit: semanage_genhomedircon returned error code -1. (Numerical result out of range). > OSError: Numerical result out of range > > Signed-off-by: Petr Lautrbach Acked-by: Nicolas Iooss > --- > libsemanage/src/genhomedircon.c | 20 +++++++++++++++++--- > 1 file changed, 17 insertions(+), 3 deletions(-) > > diff --git a/libsemanage/src/genhomedircon.c b/libsemanage/src/genhomedircon.c > index 591941fb..e5f8d371 100644 > --- a/libsemanage/src/genhomedircon.c > +++ b/libsemanage/src/genhomedircon.c > @@ -1077,10 +1077,24 @@ static int get_group_users(genhomedircon_settings_t * s, > > const char *grname = selogin + 1; > > - if (getgrnam_r(grname, &grstorage, grbuf, > - (size_t) grbuflen, &group) != 0) { > - goto cleanup; > + errno = 0; > + while ( > + (retval = getgrnam_r(grname, &grstorage, grbuf, (size_t) grbuflen, &group)) != 0 && > + errno == ERANGE > + ) { > + char *new_grbuf; > + grbuflen *= 2; > + if (grbuflen < 0) > + /* the member list could exceed 2Gb on a system with a 32-bit CPU (where > + * sizeof(long) = 4) - if this ever happened, the loop would become infinite. */ > + goto cleanup; > + new_grbuf = realloc(grbuf, grbuflen); > + if (new_grbuf == NULL) > + goto cleanup; > + grbuf = new_grbuf; > } > + if (retval != 0) > + goto cleanup; > > if (group == NULL) { > ERR(s->h_semanage, "Can't find group named %s\n", grname); > -- > 2.20.1 >