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Message-ID: <20241108010254.2995438-1-kuba@kernel.org>
Date: Thu, 7 Nov 2024 17:02:54 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
edumazet@...gle.com,
pabeni@...hat.com,
Jakub Kicinski <kuba@...nel.org>,
Simon Horman <horms@...nel.org>,
jhs@...atatu.com,
xiyou.wangcong@...il.com,
jiri@...nulli.us
Subject: [PATCH net-next v2] net: sched: cls_api: improve the error message for ID allocation failure
We run into an exhaustion problem with the kernel-allocated filter IDs.
Our allocation problem can be fixed on the user space side,
but the error message in this case was quite misleading:
"Filter with specified priority/protocol not found" (EINVAL)
Specifically when we can't allocate a _new_ ID because filter with
lowest ID already _exists_, saying "filter not found", is confusing.
Kernel allocates IDs in range of 0xc0000 -> 0x8000, giving out ID one
lower than lowest existing in that range. The error message makes sense
when tcf_chain_tp_find() gets called for GET and DEL but for NEW we
need to provide more specific error messages for all three cases:
- user wants the ID to be auto-allocated but filter with ID 0x8000
already exists
- filter already exists and can be replaced, but user asked
for a protocol change
- filter doesn't exist
Caller of tcf_chain_tp_insert_unique() doesn't set extack today,
so don't bother plumbing it in.
Reviewed-by: Simon Horman <horms@...nel.org>
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
v1 was sent a while back, I realized this is sitting in my tree
I think I just forgot to send v2.
v2:
- don't add the extack if we don't find the filter during NEW
v1: https://lore.kernel.org/20240912215306.2060709-1-kuba@kernel.org
CC: jhs@...atatu.com
CC: xiyou.wangcong@...il.com
CC: jiri@...nulli.us
---
net/sched/cls_api.c | 39 +++++++++++++++++++++++++--------------
1 file changed, 25 insertions(+), 14 deletions(-)
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 2a7d856cc334..5c8d39b6b107 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -1933,7 +1933,8 @@ static void tcf_chain_tp_remove(struct tcf_chain *chain,
static struct tcf_proto *tcf_chain_tp_find(struct tcf_chain *chain,
struct tcf_chain_info *chain_info,
u32 protocol, u32 prio,
- bool prio_allocate);
+ bool prio_allocate,
+ struct netlink_ext_ack *extack);
/* Try to insert new proto.
* If proto with specified priority already exists, free new proto
@@ -1957,8 +1958,7 @@ static struct tcf_proto *tcf_chain_tp_insert_unique(struct tcf_chain *chain,
return ERR_PTR(-EAGAIN);
}
- tp = tcf_chain_tp_find(chain, &chain_info,
- protocol, prio, false);
+ tp = tcf_chain_tp_find(chain, &chain_info, protocol, prio, false, NULL);
if (!tp)
err = tcf_chain_tp_insert(chain, &chain_info, tp_new);
mutex_unlock(&chain->filter_chain_lock);
@@ -2018,7 +2018,8 @@ static void tcf_chain_tp_delete_empty(struct tcf_chain *chain,
static struct tcf_proto *tcf_chain_tp_find(struct tcf_chain *chain,
struct tcf_chain_info *chain_info,
u32 protocol, u32 prio,
- bool prio_allocate)
+ bool prio_allocate,
+ struct netlink_ext_ack *extack)
{
struct tcf_proto **pprev;
struct tcf_proto *tp;
@@ -2029,9 +2030,14 @@ static struct tcf_proto *tcf_chain_tp_find(struct tcf_chain *chain,
pprev = &tp->next) {
if (tp->prio >= prio) {
if (tp->prio == prio) {
- if (prio_allocate ||
- (tp->protocol != protocol && protocol))
+ if (prio_allocate) {
+ NL_SET_ERR_MSG(extack, "Lowest ID from auto-alloc range already in use");
+ return ERR_PTR(-ENOSPC);
+ }
+ if (tp->protocol != protocol && protocol) {
+ NL_SET_ERR_MSG(extack, "Protocol mismatch for filter with specified priority");
return ERR_PTR(-EINVAL);
+ }
} else {
tp = NULL;
}
@@ -2312,9 +2318,8 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
mutex_lock(&chain->filter_chain_lock);
tp = tcf_chain_tp_find(chain, &chain_info, protocol,
- prio, prio_allocate);
+ prio, prio_allocate, extack);
if (IS_ERR(tp)) {
- NL_SET_ERR_MSG(extack, "Filter with specified priority/protocol not found");
err = PTR_ERR(tp);
goto errout_locked;
}
@@ -2539,10 +2544,13 @@ static int tc_del_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
mutex_lock(&chain->filter_chain_lock);
tp = tcf_chain_tp_find(chain, &chain_info, protocol,
- prio, false);
- if (!tp || IS_ERR(tp)) {
+ prio, false, extack);
+ if (!tp) {
+ err = -ENOENT;
NL_SET_ERR_MSG(extack, "Filter with specified priority/protocol not found");
- err = tp ? PTR_ERR(tp) : -ENOENT;
+ goto errout_locked;
+ } else if (IS_ERR(tp)) {
+ err = PTR_ERR(tp);
goto errout_locked;
} else if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], tp->ops->kind)) {
NL_SET_ERR_MSG(extack, "Specified filter kind does not match existing one");
@@ -2679,11 +2687,14 @@ static int tc_get_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
mutex_lock(&chain->filter_chain_lock);
tp = tcf_chain_tp_find(chain, &chain_info, protocol,
- prio, false);
+ prio, false, extack);
mutex_unlock(&chain->filter_chain_lock);
- if (!tp || IS_ERR(tp)) {
+ if (!tp) {
+ err = -ENOENT;
NL_SET_ERR_MSG(extack, "Filter with specified priority/protocol not found");
- err = tp ? PTR_ERR(tp) : -ENOENT;
+ goto errout;
+ } else if (IS_ERR(tp)) {
+ err = PTR_ERR(tp);
goto errout;
} else if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], tp->ops->kind)) {
NL_SET_ERR_MSG(extack, "Specified filter kind does not match existing one");
--
2.47.0
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