Re: [PATCH ghak90 (was ghak32) V4 01/10] audit: collect audit task parameters

Richard Guy Briggs
2019-01-03T20:29:38Z

I'm not sure what's going on here, but it looks like HTML-encoded reply
quoting making the quoted text very difficult to read. All the previous
">" have been converted to the HTML "&gt;" encoding. Your most recent
reply text looks mostly fine.

On 2019-01-03 15:10, Paul Moore wrote:
> On Thu, Nov 1, 2018 at 6:07 PM Richard Guy Briggs <rgb@redhat.com> wrote:
> &gt; On 2018-10-19 19:15, Paul Moore wrote:
> &gt; &gt; On Sun, Aug 5, 2018 at 4:32 AM Richard Guy Briggs
> <rgb@redhat.com> wrote:
> &gt; &gt; &gt; The audit-related parameters in struct task_struct
> should ideally be
> &gt; &gt; &gt; collected together and accessed through a standard audit API.
> &gt; &gt; &gt;
> &gt; &gt; &gt; Collect the existing loginuid, sessionid and
> audit_context together in a
> &gt; &gt; &gt; new struct audit_task_info called "audit" in struct task_struct.
> &gt; &gt; &gt;
> &gt; &gt; &gt; Use kmem_cache to manage this pool of memory.
> &gt; &gt; &gt; Un-inline audit_free() to be able to always recover that memory.
> &gt; &gt; &gt;
> &gt; &gt; &gt; See: https://github.com/linux-audit/audit-kernel/issues/81
> &gt; &gt; &gt;
> &gt; &gt; &gt; Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> &gt; &gt; &gt; ---
> &gt; &gt; &gt; include/linux/audit.h | 34 ++++++++++++++++++++++++----------
> &gt; &gt; &gt; include/linux/sched.h | 5 +----
> &gt; &gt; &gt; init/init_task.c | 3 +--
> &gt; &gt; &gt; init/main.c | 2 ++
> &gt; &gt; &gt; kernel/auditsc.c | 51
> ++++++++++++++++++++++++++++++++++++++++++---------
> &gt; &gt; &gt; kernel/fork.c | 4 +++-
> &gt; &gt; &gt; 6 files changed, 73 insertions(+), 26 deletions(-)
> &gt; &gt;
> &gt; &gt; ...
> &gt; &gt;
> &gt; &gt; &gt; diff --git a/include/linux/sched.h b/include/linux/sched.h
> &gt; &gt; &gt; index 87bf02d..e117272 100644
> &gt; &gt; &gt; --- a/include/linux/sched.h
> &gt; &gt; &gt; +++ b/include/linux/sched.h
> &gt; &gt; &gt; @@ -873,10 +872,8 @@ struct task_struct {
> &gt; &gt; &gt;
> &gt; &gt; &gt; struct callback_head *task_works;
> &gt; &gt; &gt;
> &gt; &gt; &gt; - struct audit_context *audit_context;
> &gt; &gt; &gt; #ifdef CONFIG_AUDITSYSCALL
> &gt; &gt; &gt; - kuid_t loginuid;
> &gt; &gt; &gt; - unsigned int sessionid;
> &gt; &gt; &gt; + struct audit_task_info *audit;
> &gt; &gt; &gt; #endif
> &gt; &gt; &gt; struct seccomp seccomp;
> &gt; &gt;
> &gt; &gt; Prior to this patch audit_context was available regardless of
> &gt; &gt; CONFIG_AUDITSYSCALL, after this patch the corresponding audit_context
> &gt; &gt; is only available when CONFIG_AUDITSYSCALL is defined.
> &gt;
> &gt; This was intentional since audit_context is not used when AUDITSYSCALL is
> &gt; disabled. audit_alloc() was stubbed in that case to return 0.
> audit_context()
> &gt; returned NULL.
> &gt;
> &gt; The fact that audit_context was still present in struct task_struct was an
> &gt; oversight in the two patches already accepted:
> &gt; ("audit: use inline function to get audit context")
> &gt; ("audit: use inline function to get audit context")
> &gt; that failed to hide or remove it from struct task_struct when it
> was no longer
> &gt; relevant.
>
> Okay, in that case let's pull this out and fix this separately from
> the audit container ID patchset.
>
> &gt; On further digging, loginuid and sessionid (and
> audit_log_session_info) should
> &gt; be part of CONFIG_AUDIT scope and not CONFIG_AUDITSYSCALL since
> it is used in
> &gt; CONFIG_CHANGE, ANOM_LINK, FEATURE_CHANGE(, INTEGRITY_RULE), none
> of which are
> &gt; otherwise dependent on AUDITSYSCALL.
>
> This looks like something else we should fix independently from this patchset.
>
> &gt; Looking ahead, contid should be treated like loginuid and
> sessionid, which are
> &gt; currently only available when syscall auditting is.
>
> That seems reasonable. Eventually it would be great if we got rid of
> CONFIG_AUDITSYSCALL, but that is a separate issue, and something that
> is going to require work from the different arch/ABI folks to ensure
> everything is working properly.
>
> &gt; Converting records from standalone to syscall and checking
> audit_dummy_context
> &gt; changes the nature of CONFIG_AUDIT/!CONFIG_AUDITSYSCALL separation.
> &gt; eg: ANOM_LINK accompanied by PATH record (which needed CWD addition to be
> &gt; complete anyways)
> &gt;
> &gt; &gt; &gt; diff --git a/init/main.c b/init/main.c
> &gt; &gt; &gt; index 3b4ada1..6aba171 100644
> &gt; &gt; &gt; --- a/init/main.c
> &gt; &gt; &gt; +++ b/init/main.c
> &gt; &gt; &gt; @@ -92,6 +92,7 @@
> &gt; &gt; &gt; #include <linux rodata_test.h="">
> &gt; &gt; &gt; #include <linux jump_label.h="">
> &gt; &gt; &gt; #include <linux mem_encrypt.h="">
> &gt; &gt; &gt; +#include <linux audit.h="">
> &gt; &gt; &gt;
> &gt; &gt; &gt; #include <asm io.h="">
> &gt; &gt; &gt; #include <asm bugs.h="">
> &gt; &gt; &gt; @@ -721,6 +722,7 @@ asmlinkage __visible void __init
> start_kernel(void)
> &gt; &gt; &gt; nsfs_init();
> &gt; &gt; &gt; cpuset_init();
> &gt; &gt; &gt; cgroup_init();
> &gt; &gt; &gt; + audit_task_init();
> &gt; &gt; &gt; taskstats_init_early();
> &gt; &gt; &gt; delayacct_init();
> &gt; &gt;
> &gt; &gt; It seems like we would need either init_struct_audit or
> &gt; &gt; audit_task_init(), but not both, yes?
> &gt;
> &gt; One sets initial values of init task via an included struct,
> other makes a call
> &gt; to create the kmem cache. Both seem appropriate to me unless we move the
> &gt; initialization from a struct to assignments in audit_task_init(),
> but I'm not
> &gt; that comfortable separating the audit init values from the rest of the
> &gt; task_struct init task initializers (though there are other
> subsystems that need
> &gt; to do so dynamically).
>
> My original thinking was focused on the use of init_struct_audit as an
> initializer when audit_task_init() was already creating a kmem_cache
> pool and a zero'd/init'd audit_task_info could be obtained via the
> usual kmem_cache functions. Alternatively, although I don't believe
> it would be recommended for this case, would be to use
> init_struct_audit as an init helper if we included the audit_task_info
> struct directly in the task_struct, as opposed to a pointer. What I
> missed was the simple fact that you're only using init_struct_audit
> for the init_task, which pretty much makes my original question rather
> silly :)
>
> --
> paul moore
> www.paul-moore.com

- RGB

--
Richard Guy Briggs <rgb@redhat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635