Re: [PATCH] audit: process errors from filter user rules

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 <rgb(a)redhat.com&gt; > --- > 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)