Re: [PATCH ghak138] audit: move audit_return_fixup before the filters

From: Paul Moore
Date: Thu Aug 25 2022 - 09:21:15 EST

On Wed, Aug 24, 2022 at 11:10 PM Richard Guy Briggs <rgb@xxxxxxxxxx> wrote:
>
> The success and return_code are needed by the filters. Move
> audit_return_fixup() before the filters.
>
> The pid member of struct audit_context is never used. Remove it.
>
> The audit_reset_context() comment about unconditionally resetting
> "ctx->state" should read "ctx->context".
>
> The proctitle is intentionally stored between syscalls. Only free it in
> audit_free_context().
>
> Be explicit in checking the struct audit_context "context" member enum
> value rather than assuming the order of context enum values.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 12c5e81d3fd0 ("audit: prepare audit_context for use in calling contexts beyond syscalls")
> Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
> ---
> kernel/audit.h | 2 +-
> kernel/auditsc.c | 12 ++++++------
> 2 files changed, 7 insertions(+), 7 deletions(-)

[NOTE: dropped the stable kernel alias from my reply]

A couple of things:

* I know you like to CC a lot of people on your patches Richard, but
just a heads-up that you are likely to get a nastygram back from Greg
about CC'ing the stable kernel alias directly. It's probably worth
re-reading the Documentation/process/stable-kernel-rules.rst docs if
you haven't done so in a while, it's a quick read and I do it myself
every few months.

* I generally ask that people *not* directly add the 'Cc: stable@...`
tag to patches they send to the list, I prefer to add/remove those as
needed. It's not a hard rule, just something I prefer (and don't
respin patches *only* to remove the tag, but keep this in mind for
future submissions/respins). If there is ever any concern about the
stable tag I bring that up for discussion on-list, although that has
only ever happened once (twice?) that I can recall; it's usually
pretty obvious.

* Despite what I said about the stable tagging, please continue to add
the 'Fixes: ...' tags for serious bugs, those are good and welcome.

* The audit_return_fixup() is definitely -rc/stable material, which
means it should be split into its own patch.

* The proctitle free change *might* be stable worthy, but I'd like to
hear some more justification of this from you either in a reply on
this thread or in a commit description. Regardless, just like the
return fix, this should be in a separate patch.

* The enum comparison should be its own patch, with an appropriate
'Fixes:' tag in case the -stable folks want to merge it, but as we
haven't seen any problems with it (and they aren't likely) I wouldn't
tag this for -stable.

* I would suggest the audit_context::pid removal and the comment fix
be separate patches as well. I would also suggest omitting a 'Fixes:'
tag here as these are far from critical, and things with a fixes tag
tend to get pulled into -stable kernels which I believe would be a
mistake here.

> diff --git a/kernel/audit.h b/kernel/audit.h
> index 58b66543b4d5..d6eb7b59c791 100644
> --- a/kernel/audit.h
> +++ b/kernel/audit.h
> @@ -133,7 +133,7 @@ struct audit_context {
> struct sockaddr_storage *sockaddr;
> size_t sockaddr_len;
> /* Save things to print about task_struct */
> - pid_t pid, ppid;
> + pid_t ppid;
> kuid_t uid, euid, suid, fsuid;
> kgid_t gid, egid, sgid, fsgid;
> unsigned long personality;
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index 9226746dcf0a..9f8c05228d6d 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -965,7 +965,7 @@ static void audit_reset_context(struct audit_context *ctx)
> if (!ctx)
> return;
>
> - /* if ctx is non-null, reset the "ctx->state" regardless */
> + /* if ctx is non-null, reset the "ctx->context" regardless */
> ctx->context = AUDIT_CTX_UNUSED;
> if (ctx->dummy)
> return;
> @@ -1002,7 +1002,7 @@ static void audit_reset_context(struct audit_context *ctx)
> kfree(ctx->sockaddr);
> ctx->sockaddr = NULL;
> ctx->sockaddr_len = 0;
> - ctx->pid = ctx->ppid = 0;
> + ctx->ppid = 0;
> ctx->uid = ctx->euid = ctx->suid = ctx->fsuid = KUIDT_INIT(0);
> ctx->gid = ctx->egid = ctx->sgid = ctx->fsgid = KGIDT_INIT(0);
> ctx->personality = 0;
> @@ -1016,7 +1016,6 @@ static void audit_reset_context(struct audit_context *ctx)
> WARN_ON(!list_empty(&ctx->killed_trees));
> audit_free_module(ctx);
> ctx->fds[0] = -1;
> - audit_proctitle_free(ctx);
> ctx->type = 0; /* reset last for audit_free_*() */
> }
>
> @@ -1077,6 +1076,7 @@ static inline void audit_free_context(struct audit_context *context)
> {
> /* resetting is extra work, but it is likely just noise */
> audit_reset_context(context);
> + audit_proctitle_free(context);
> free_tree_refs(context);
> kfree(context->filterkey);
> kfree(context);
> @@ -1940,6 +1940,7 @@ void __audit_uring_exit(int success, long code)
> goto out;
> }
>
> + audit_return_fixup(ctx, success, code);
> if (ctx->context == AUDIT_CTX_SYSCALL) {
> /*
> * NOTE: See the note in __audit_uring_entry() about the case
> @@ -1981,7 +1982,6 @@ void __audit_uring_exit(int success, long code)
> audit_filter_inodes(current, ctx);
> if (ctx->current_state != AUDIT_STATE_RECORD)
> goto out;
> - audit_return_fixup(ctx, success, code);
> audit_log_exit();
>
> out:
> @@ -2065,13 +2065,13 @@ void __audit_syscall_exit(int success, long return_code)
> if (!list_empty(&context->killed_trees))
> audit_kill_trees(context);
>
> + audit_return_fixup(context, success, return_code);
> /* run through both filters to ensure we set the filterkey properly */
> audit_filter_syscall(current, context);
> audit_filter_inodes(current, context);
> - if (context->current_state < AUDIT_STATE_RECORD)
> + if (context->current_state != AUDIT_STATE_RECORD)
> goto out;
>
> - audit_return_fixup(context, success, return_code);
> audit_log_exit();
>
> out:
> --
> 2.27.0

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