* [PATCH] audit: process errors from filter user rules
@ 2013-12-05 3:45 Richard Guy Briggs
2013-12-05 20:52 ` Eric Paris
0 siblings, 1 reply; 3+ messages in thread
From: Richard Guy Briggs @ 2013-12-05 3:45 UTC (permalink / raw)
To: linux-audit, linux-kernel; +Cc: Richard Guy Briggs, Eric Paris, Steve Grubb
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@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)
--
1.7.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] audit: process errors from filter user rules
2013-12-05 3:45 [PATCH] audit: process errors from filter user rules Richard Guy Briggs
@ 2013-12-05 20:52 ` Eric Paris
2013-12-09 20:21 ` Richard Guy Briggs
0 siblings, 1 reply; 3+ messages in thread
From: Eric Paris @ 2013-12-05 20:52 UTC (permalink / raw)
To: Richard Guy Briggs; +Cc: linux-audit, linux-kernel, Steve Grubb
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@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)
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] audit: process errors from filter user rules
2013-12-05 20:52 ` Eric Paris
@ 2013-12-09 20:21 ` Richard Guy Briggs
0 siblings, 0 replies; 3+ messages in thread
From: Richard Guy Briggs @ 2013-12-09 20:21 UTC (permalink / raw)
To: Eric Paris; +Cc: linux-audit, linux-kernel, Steve Grubb
On 13/12/05, Eric Paris wrote:
> 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...
Your original code suggestion was cleaner and simpler than mine, but I
tried to code it in a structured manner without gotos, perhaps naively
believing structured code to be superior. I think that effort backfired
and made it more complex. I'm ok going back to your original ideas.
I do still think that retry and passing back of error codes is the
better approach.
> Just log the messages on any error, even with a dontaudit rule... How
> about a function like:
I suspect this isn't what you intended. The way this is written, it
always breaks after the first rule, not checking any of the others.
> 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;
> }
Did you mean?
list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
rc = audit_filter_user_rules(&e->rule, type, &state);
if (rc) {
if (rc > 0 && state == AUDIT_DISABLED)
ret = 0;
break;
}
}
> and use some sense with the 80 character line length rule. It's 81
> long. Just let it be long even if checkpatch whines....
Yeah, I haven't been too pedantic about line length warnings barely over
80 characters when it affects readability...
> -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@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)
>
>
- RGB
--
Richard Guy Briggs <rbriggs@redhat.com>
Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
Remote, Ottawa, Canada
Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545
^ permalink raw reply [flat|nested] 3+ messages in thread
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