On 3/15/2022 4:47 PM, Paul Moore wrote:
On Thu, Mar 10, 2022 at 6:59 PM Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote:Replace the single skb pointer in an audit_buffer with a list of skb pointers. Add the audit_stamp information to the audit_buffer as there's no guarantee that there will be an audit_context containing the stamp associated with the event. At audit_log_end() time create auxiliary records (none are currently defined) as have been added to the list. Suggested-by: Paul Moore <paul@xxxxxxxxxxxxxx> Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx> --- kernel/audit.c | 53 +++++++++++++++++++++++++++++++++----------------- 1 file changed, 35 insertions(+), 18 deletions(-) diff --git a/kernel/audit.c b/kernel/audit.c index f012c3786264..4713e66a12af 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -197,8 +197,10 @@ static struct audit_ctl_mutex { * to place it on a transmit queue. Multiple audit_buffers can be in * use simultaneously. */ struct audit_buffer { - struct sk_buff *skb; /* formatted skb ready to send */ + struct sk_buff *skb; /* the skb for audit_log functions */ + struct sk_buff_head skb_list; /* formatted skbs, ready to send */ struct audit_context *ctx; /* NULL or associated context */ + struct audit_stamp stamp; /* audit stamp for these records */ gfp_t gfp_mask; }; @@ -1744,7 +1746,6 @@ static void audit_buffer_free(struct audit_buffer *ab) if (!ab) return; - kfree_skb(ab->skb);I like the safety in knowing that audit_buffer_free() would free the ab->skb memory, I'm not sure I want to get rid of that. With the understanding that ab->skb is always going to be present somewhere in ab->skb_list, any reason not to do something like this? while ((skb = skb_dequeue(&ab->skb_list))) kfree_skb(skb);
Sure, I'll give this a try. Thanks for the review and suggestions.
kmem_cache_free(audit_buffer_cache, ab); } @@ -1760,11 +1761,15 @@ static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx, ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask); if (!ab->skb) goto err; - if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0)) + if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0)) { + kfree_skb(ab->skb); goto err; + }Assuming we restore the audit_buffer_free() functionality as mentioned above, if we move the ab->skb_list init and enqueue calls before we attempt the nlmsg_put() we can drop the kfree_skb() call and just use the existing audit_buffer_free() call at the err target.ab->ctx = ctx; ab->gfp_mask = gfp_mask; + skb_queue_head_init(&ab->skb_list); + skb_queue_tail(&ab->skb_list, ab->skb); return ab;-- paul-moore.com
