From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ondrej Mosnacek Subject: Re: [PATCH ghak95] audit: Do not log full CWD path on empty relative paths Date: Fri, 24 Aug 2018 14:59:10 +0200 Message-ID: References: <20180802114436.1209-1-omosnace@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com (ext-mx20.extmail.prod.ext.phx2.redhat.com [10.5.110.49]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9A66C106A7A5 for ; Fri, 24 Aug 2018 12:59:22 +0000 (UTC) Received: from mail-oi0-f70.google.com (mail-oi0-f70.google.com [209.85.218.70]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1F14B30B8FA4 for ; Fri, 24 Aug 2018 12:59:22 +0000 (UTC) Received: by mail-oi0-f70.google.com with SMTP id j5-v6so7525871oiw.13 for ; Fri, 24 Aug 2018 05:59:22 -0700 (PDT) In-Reply-To: <20180802114436.1209-1-omosnace@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-audit-bounces@redhat.com Errors-To: linux-audit-bounces@redhat.com To: Linux-Audit Mailing List Cc: Richard Guy Briggs List-Id: linux-audit@redhat.com On Thu, Aug 2, 2018 at 1:45 PM Ondrej Mosnacek wrote: > When a relative path has just a single component and we want to emit a > nametype=PARENT record, the current implementation just reports the full > CWD path (which is alrady available in the audit context). > > This is wrong for three reasons: > 1. Wasting log space for redundant data (CWD path is already in the CWD > record). > 2. Inconsistency with other PATH records (if a relative PARENT directory > path contains at least one component, only the verbatim relative path > is logged). > 3. In some syscalls (e.g. openat(2)) the relative path may not even be > relative to the CWD, but to another directory specified as a file > descriptor. In that case the logged path is simply plain wrong. > > This patch modifies this behavior to simply report "." in the > aforementioned case, which is equivalent to an "empty" directory path > and can be concatenated with the actual base directory path (CWD or > dirfd from openat(2)-like syscall) once support for its logging is added > later. In the meantime, defaulting to CWD as base directory on relative > paths (as already done by the userspace tools) will be enough to achieve > results equivalent to the current behavior. I tested this patch a little bit with the libauparse library (it has some functions for normalizing paths extracted from the records) and it seems to behave as intended. The userspace functions seem to take a rather crude approach and I think they won't always properly normalize some paths, but that is a separate issue and this patch at least definitely doesn't make it worse. > > See: https://github.com/linux-audit/audit-kernel/issues/95 > > Fixes: 9c937dcc7102 ("[PATCH] log more info for directory entry change events") > Signed-off-by: Ondrej Mosnacek > --- > kernel/audit.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/kernel/audit.c b/kernel/audit.c > index 2a8058764aa6..4f18bd48eb4b 100644 > --- a/kernel/audit.c > +++ b/kernel/audit.c > @@ -2127,28 +2127,27 @@ void audit_log_name(struct audit_context *context, struct audit_names *n, > > audit_log_format(ab, "item=%d", record_num); > > + audit_log_format(ab, " name="); > if (path) > - audit_log_d_path(ab, " name=", path); > + audit_log_d_path(ab, NULL, path); > else if (n->name) { > switch (n->name_len) { > case AUDIT_NAME_FULL: > /* log the full path */ > - audit_log_format(ab, " name="); > audit_log_untrustedstring(ab, n->name->name); > break; > case 0: > /* name was specified as a relative path and the > * directory component is the cwd */ > - audit_log_d_path(ab, " name=", &context->pwd); > + audit_log_untrustedstring(ab, "."); > break; > default: > /* log the name's directory component */ > - audit_log_format(ab, " name="); > audit_log_n_untrustedstring(ab, n->name->name, > n->name_len); > } > } else > - audit_log_format(ab, " name=(null)"); > + audit_log_format(ab, "(null)"); > > if (n->ino != AUDIT_INO_UNSET) > audit_log_format(ab, " inode=%lu" > -- > 2.17.1 > -- Ondrej Mosnacek Associate Software Engineer, Security Technologies Red Hat, Inc.