Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753717AbaAMRWz (ORCPT ); Mon, 13 Jan 2014 12:22:55 -0500 Received: from mail-we0-f178.google.com ([74.125.82.178]:62881 "EHLO mail-we0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752294AbaAMRWv convert rfc822-to-8bit (ORCPT ); Mon, 13 Jan 2014 12:22:51 -0500 MIME-Version: 1.0 In-Reply-To: <1389632555-7039-3-git-send-email-wroberts@tresys.com> References: <1389632555-7039-1-git-send-email-wroberts@tresys.com> <1389632555-7039-3-git-send-email-wroberts@tresys.com> Date: Mon, 13 Jan 2014 12:22:41 -0500 Message-ID: Subject: Re: [RFC][PATCH v3 3/3] audit: Audit proc cmdline value From: William Roberts To: "linux-audit@redhat.com" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Richard Guy Briggs , "viro@zeniv.linux.org.uk" , akpm@linux-foundation.org, Stephen Smalley Cc: William Roberts Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 13, 2014 at 12:02 PM, William Roberts wrote: > During an audit event, cache and print the value of the process's > cmdline value (proc//cmdline). This is useful in situations > where processes are started via fork'd virtual machines where the > comm field is incorrect. Often times, setting the comm field still > is insufficient as the comm width is not very wide and most > virtual machine "package names" do not fit. Also, during execution, > many threads have their comm field set as well. By tying it back to > the global cmdline value for the process, audit records will be more > complete in systems with these properties. An example of where this > is useful and applicable is in the realm of Android. With Android, > their is no fork/exec for VM instances. The bare, preloaded Dalvik > VM listens for a fork and specialize request. When this request comes > in, the VM forks, and the loads the specific application (specializing). > This was done to take advantage of COW and to not require a load of > basic packages by the VM on very app spawn. When this spawn occurs, > the package name is set via setproctitle() and shows up in procfs. > Many of these package names are longer then 16 bytes, the historical > width of task->comm. Having the cmdline in the audit records will > couple the application back to the record directly. Also, on my > Debian development box, some audit records were more useful then > what was printed under comm. > > The cached cmdline is tied to the life-cycle of the audit_context > structure and is built on demand. > > Example denial prior to patch (Ubuntu): > CALL msg=audit(1387828084.070:361): arch=c000003e syscall=82 success=yes exit=0 a0=4184bf a1=418547 a2=0 a3=0 items=0 ppid=1 pid=1329 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 ses=4294967295 tty=(none) comm="console-kit-dae" exe="/usr/sbin/console-kit-daemon" subj=system_u:system_r:consolekit_t:s0-s0:c0.c255 key=(null) > > After Patches (Ubuntu): > type=SYSCALL msg=audit(1387828084.070:361): arch=c000003e syscall=82 success=yes exit=0 a0=4184bf a1=418547 a2=0 a3=0 items=0 ppid=1 pid=1329 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 ses=4294967295 tty=(none) comm="console-kit-dae" exe="/usr/sbin/console-kit-daemon" subj=system_u:system_r:consolekit_t:s0-s0:c0.c255 key=(null) cmdline="/usr/lib/dbus-1.0/dbus-daemon-launch-helper" > > Example denial prior to patch (Android): > type=1300 msg=audit(248323.940:247): arch=40000028 syscall=54 per=840000 success=yes exit=0 a0=39 a1=540b a2=2 a3=750eecec items=0 ppid=224 pid=1858 auid=4294967295 uid=1002 gid=1002 euid=1002 suid=1002 fsuid=1002 egid=1002 sgid=1002 fsgid=1002 tty=(none) ses=4294967295 comm="bt_hc_worker" exe="/system/bin/app_process" subj=u:r:bluetooth:s0 key=(null) > > After Patches (Android): > type=1300 msg=audit(248323.940:247): arch=40000028 syscall=54 per=840000 success=yes exit=0 a0=39 a1=540b a2=2 a3=750eecec items=0 ppid=224 pid=1858 auid=4294967295 uid=1002 gid=1002 euid=1002 suid=1002 fsuid=1002 egid=1002 sgid=1002 fsgid=1002 tty=(none) ses=4294967295 comm="bt_hc_worker" exe="/system/bin/app_process" subj=u:r:bluetooth:s0 key=(null) cmdline="com.android.bluetooth" > > Signed-off-by: William Roberts > --- > kernel/audit.h | 1 + > kernel/auditsc.c | 43 +++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 44 insertions(+) > > diff --git a/kernel/audit.h b/kernel/audit.h > index b779642..bd6211f 100644 > --- a/kernel/audit.h > +++ b/kernel/audit.h > @@ -202,6 +202,7 @@ struct audit_context { > } execve; > }; > int fds[2]; > + char *cmdline; > > #if AUDIT_DEBUG > int put_count; > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > index 90594c9..08bdbec 100644 > --- a/kernel/auditsc.c > +++ b/kernel/auditsc.c > @@ -842,6 +842,12 @@ static inline struct audit_context *audit_get_context(struct task_struct *tsk, > return context; > } > > +static inline void audit_cmdline_free(struct audit_context *context) > +{ > + kfree(context->cmdline); > + context->cmdline = NULL; > +} > + > static inline void audit_free_names(struct audit_context *context) > { > struct audit_names *n, *next; > @@ -955,6 +961,7 @@ static inline void audit_free_context(struct audit_context *context) > audit_free_aux(context); > kfree(context->filterkey); > kfree(context->sockaddr); > + audit_cmdline_free(context); > kfree(context); > } > > @@ -1271,6 +1278,41 @@ static void show_special(struct audit_context *context, int *call_panic) > audit_log_end(ab); > } > > +static void audit_log_cmdline(struct audit_buffer *ab, struct task_struct *tsk, > + struct audit_context *context) > +{ > + int res; > + char *buf; > + char *msg = "(null)"; > + audit_log_format(ab, " cmdline="); > + > + /* Not cached */ > + if (!context->cmdline) { > + buf = kmalloc(PATH_MAX, GFP_KERNEL); > + if (!buf) > + goto out; > + res = get_cmdline(tsk, buf, PATH_MAX); > + if (res == 0) { > + kfree(buf); > + goto out; > + } > + /* > + * Ensure NULL terminated but don't clobber the end > + * unless the buffer is full. Worst case you end up > + * with 2 null bytes ending it. By doing it this way > + * one avoids additional branching. One checking if the > + * end is null and another to check if their should be > + * an increment before setting the null byte. > + */ > + res -= res == PATH_MAX; > + buf[res] = '\0'; > + context->cmdline = buf; > + } > + msg = context->cmdline; > +out: > + audit_log_untrustedstring(ab, msg); > +} > + > static void audit_log_exit(struct audit_context *context, struct task_struct *tsk) > { > int i, call_panic = 0; > @@ -1303,6 +1345,7 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts > > audit_log_task_info(ab, tsk); > audit_log_key(ab, context->filterkey); > + audit_log_cmdline(ab, tsk, context); > audit_log_end(ab); > > for (aux = context->aux; aux; aux = aux->next) { > -- > 1.7.9.5 > Incorrect patch version v3, should be v2. Sorry for the confusion. Ill resend the proper subj. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/