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

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