I know we talked about this patch, and it seemed like a good idea at the
time, but honestly, these races are so rare, it isn't worth the code
complexity. I tried to simplify the readability of your code and got
something better, but still the loop is needless...
Just log the messages on any error, even with a dontaudit rule... How
about a function like:
int audit_filter_user(int type)
{
enum audit_state state = AUDIT_DISABLED;
struct audit_entry *e;
int rc, ret;
ret = 1; /* Audit by default */
rcu_read_lock();
list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list)
{
rc = audit_filter_user_rules(&e->rule, type, &state);
if (rc > 0 && state == AUDIT_DISABLED)
ret = 0;
break;
}
rcu_read_unlock();
return ret;
}
and use some sense with the 80 character line length rule. It's 81
long. Just let it be long even if checkpatch whines....
-Eric
On Wed, 2013-12-04 at 22:45 -0500, Richard Guy Briggs wrote:
> Errors from filter user rules were previously ignored, and worse, an error on
> a AUDIT_NEVER rule disabled logging on that rule. On -ESTALE, retry up to 5
> times. On error on AUDIT_NEVER rules, log.
>
> Signed-off-by: Richard Guy Briggs <r...@redhat.com>
> ---
> kernel/audit.c | 2 +-
> kernel/auditfilter.c | 44 +++++++++++++++++++++++++++++++-------------
> 2 files changed, 32 insertions(+), 14 deletions(-)
>
> diff --git a/kernel/audit.c b/kernel/audit.c
> index 4cbc945..c93cf06 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -706,7 +706,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct
> nlmsghdr *nlh)
> return 0;
>
> err = audit_filter_user(msg_type);
> - if (err == 1) {
> + if (err) { /* match or error */
> err = 0;
> if (msg_type == AUDIT_USER_TTY) {
> err = tty_audit_push_current();
> diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> index b4c6e03..1a7dfa5 100644
> --- a/kernel/auditfilter.c
> +++ b/kernel/auditfilter.c
> @@ -1272,8 +1272,8 @@ static int audit_filter_user_rules(struct audit_krule
> *rule, int type,
> break;
> }
>
> - if (!result)
> - return 0;
> + if (result <= 0)
> + return result;
> }
> switch (rule->action) {
> case AUDIT_NEVER: *state = AUDIT_DISABLED; break;
> @@ -1286,19 +1286,37 @@ int audit_filter_user(int type)
> {
> enum audit_state state = AUDIT_DISABLED;
> struct audit_entry *e;
> - int ret = 1;
> -
> - rcu_read_lock();
> - list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list)
> {
> - if (audit_filter_user_rules(&e->rule, type, &state)) {
> - if (state == AUDIT_DISABLED)
> - ret = 0;
> - break;
> + int rc, count = 0, retry = 0, ret = 1; /* Audit by default */
> +#define FILTER_RETRY_LIMIT 5
> +
> + do {
> + rcu_read_lock();
> + list_for_each_entry_rcu(e,
> + &audit_filter_list[AUDIT_FILTER_USER],
> + list) {
> + retry = 0;
> + rc = audit_filter_user_rules(&e->rule, type, &state);
> + if (rc > 0) {
> + if (state == AUDIT_DISABLED)
> + ret = 0;
> + break;
> + } else if (rc < 0) {
> + if (rc == -ESTALE && count <
> FILTER_RETRY_LIMIT) {
> + rcu_read_unlock();
> + count++;
> + retry = 1;
> + cond_resched();
> + } else {
> + ret = rc;
> + }
> + break;
> + }
> }
> - }
> - rcu_read_unlock();
> + if (!retry)
> + rcu_read_unlock();
> + } while (retry);
>
> - return ret; /* Audit by default */
> + return ret;
> }
>
> int audit_filter_type(int type)
--
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