| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20230419125254.20789-2-johannes@sipsolutions.net>
Date: Wed, 19 Apr 2023 14:52:53 +0200
From: Johannes Berg <johannes@...solutions.net>
To: netdev@...r.kernel.org
Cc: linux-wireless@...r.kernel.org,
Johannes Berg <johannes.berg@...el.com>
Subject: [PATCH net-next v4 2/3] net: extend drop reasons for multiple subsystems
From: Johannes Berg <johannes.berg@...el.com>
Extend drop reasons to make them usable by subsystems
other than core by reserving the high 16 bits for a
new subsystem ID, of which 0 of course is used for the
existing reasons immediately.
To still be able to have string reasons, restructure
that code a bit to make the loopup under RCU, the only
user of this (right now) is drop_monitor.
Link: https://lore.kernel.org/netdev/00659771ed54353f92027702c5bbb84702da62ce.camel@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
---
v3:
- new dropreason.h now that core codes are in dropreason-core.h
- annotate RCU pointer init for sparse
v4:
- fix kernel-doc, indentation
---
include/net/dropreason-core.h | 14 ++++++---
include/net/dropreason.h | 31 ++++++++++++++++++
net/core/drop_monitor.c | 33 ++++++++++++++------
net/core/skbuff.c | 59 +++++++++++++++++++++++++++++++++--
4 files changed, 121 insertions(+), 16 deletions(-)
create mode 100644 include/net/dropreason.h
diff --git a/include/net/dropreason-core.h b/include/net/dropreason-core.h
index ade6d5b9186c..a2b953b57689 100644
--- a/include/net/dropreason-core.h
+++ b/include/net/dropreason-core.h
@@ -340,12 +340,20 @@ enum skb_drop_reason {
*/
SKB_DROP_REASON_IPV6_NDISC_NS_OTHERHOST,
/**
- * @SKB_DROP_REASON_MAX: the maximum of drop reason, which shouldn't be
- * used as a real 'reason'
+ * @SKB_DROP_REASON_MAX: the maximum of core drop reasons, which
+ * shouldn't be used as a real 'reason' - only for tracing code gen
*/
SKB_DROP_REASON_MAX,
+
+ /**
+ * @SKB_DROP_REASON_SUBSYS_MASK: subsystem mask in drop reasons,
+ * see &enum skb_drop_reason_subsys
+ */
+ SKB_DROP_REASON_SUBSYS_MASK = 0xffff0000,
};
+#define SKB_DROP_REASON_SUBSYS_SHIFT 16
+
#define SKB_DR_INIT(name, reason) \
enum skb_drop_reason name = SKB_DROP_REASON_##reason
#define SKB_DR(name) \
@@ -359,6 +367,4 @@ enum skb_drop_reason {
SKB_DR_SET(name, reason); \
} while (0)
-extern const char * const drop_reasons[];
-
#endif
diff --git a/include/net/dropreason.h b/include/net/dropreason.h
new file mode 100644
index 000000000000..f0f2378dbed0
--- /dev/null
+++ b/include/net/dropreason.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _LINUX_DROPREASON_H
+#define _LINUX_DROPREASON_H
+#include <net/dropreason-core.h>
+
+/**
+ * enum skb_drop_reason_subsys - subsystem tag for (extended) drop reasons
+ */
+enum skb_drop_reason_subsys {
+ /** @SKB_DROP_REASON_SUBSYS_CORE: core drop reasons defined above */
+ SKB_DROP_REASON_SUBSYS_CORE,
+
+ /** @SKB_DROP_REASON_SUBSYS_NUM: number of subsystems defined */
+ SKB_DROP_REASON_SUBSYS_NUM
+};
+
+struct drop_reason_list {
+ const char * const *reasons;
+ size_t n_reasons;
+};
+
+/* Note: due to dynamic registrations, access must be under RCU */
+extern const struct drop_reason_list __rcu *
+drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_NUM];
+
+void drop_reasons_register_subsys(enum skb_drop_reason_subsys subsys,
+ const struct drop_reason_list *list);
+void drop_reasons_unregister_subsys(enum skb_drop_reason_subsys subsys);
+
+#endif
diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
index 5a782d1d8fd3..aff31cd944c2 100644
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -21,6 +21,7 @@
#include <linux/workqueue.h>
#include <linux/netlink.h>
#include <linux/net_dropmon.h>
+#include <linux/bitfield.h>
#include <linux/percpu.h>
#include <linux/timer.h>
#include <linux/bitops.h>
@@ -29,6 +30,7 @@
#include <net/genetlink.h>
#include <net/netevent.h>
#include <net/flow_offload.h>
+#include <net/dropreason.h>
#include <net/devlink.h>
#include <trace/events/skb.h>
@@ -504,8 +506,6 @@ static void net_dm_packet_trace_kfree_skb_hit(void *ignore,
if (!nskb)
return;
- if (unlikely(reason >= SKB_DROP_REASON_MAX || reason <= 0))
- reason = SKB_DROP_REASON_NOT_SPECIFIED;
cb = NET_DM_SKB_CB(nskb);
cb->reason = reason;
cb->pc = location;
@@ -552,9 +552,9 @@ static size_t net_dm_in_port_size(void)
}
#define NET_DM_MAX_SYMBOL_LEN 40
+#define NET_DM_MAX_REASON_LEN 50
-static size_t net_dm_packet_report_size(size_t payload_len,
- enum skb_drop_reason reason)
+static size_t net_dm_packet_report_size(size_t payload_len)
{
size_t size;
@@ -576,7 +576,7 @@ static size_t net_dm_packet_report_size(size_t payload_len,
/* NET_DM_ATTR_PROTO */
nla_total_size(sizeof(u16)) +
/* NET_DM_ATTR_REASON */
- nla_total_size(strlen(drop_reasons[reason]) + 1) +
+ nla_total_size(NET_DM_MAX_REASON_LEN + 1) +
/* NET_DM_ATTR_PAYLOAD */
nla_total_size(payload_len);
}
@@ -610,6 +610,8 @@ static int net_dm_packet_report_fill(struct sk_buff *msg, struct sk_buff *skb,
size_t payload_len)
{
struct net_dm_skb_cb *cb = NET_DM_SKB_CB(skb);
+ const struct drop_reason_list *list = NULL;
+ unsigned int subsys, subsys_reason;
char buf[NET_DM_MAX_SYMBOL_LEN];
struct nlattr *attr;
void *hdr;
@@ -627,9 +629,24 @@ static int net_dm_packet_report_fill(struct sk_buff *msg, struct sk_buff *skb,
NET_DM_ATTR_PAD))
goto nla_put_failure;
+ rcu_read_lock();
+ subsys = u32_get_bits(cb->reason, SKB_DROP_REASON_SUBSYS_MASK);
+ if (subsys < SKB_DROP_REASON_SUBSYS_NUM)
+ list = rcu_dereference(drop_reasons_by_subsys[subsys]);
+ subsys_reason = cb->reason & ~SKB_DROP_REASON_SUBSYS_MASK;
+ if (!list ||
+ subsys_reason >= list->n_reasons ||
+ !list->reasons[subsys_reason] ||
+ strlen(list->reasons[subsys_reason]) > NET_DM_MAX_REASON_LEN) {
+ list = rcu_dereference(drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_CORE]);
+ subsys_reason = SKB_DROP_REASON_NOT_SPECIFIED;
+ }
if (nla_put_string(msg, NET_DM_ATTR_REASON,
- drop_reasons[cb->reason]))
+ list->reasons[subsys_reason])) {
+ rcu_read_unlock();
goto nla_put_failure;
+ }
+ rcu_read_unlock();
snprintf(buf, sizeof(buf), "%pS", cb->pc);
if (nla_put_string(msg, NET_DM_ATTR_SYMBOL, buf))
@@ -687,9 +704,7 @@ static void net_dm_packet_report(struct sk_buff *skb)
if (net_dm_trunc_len)
payload_len = min_t(size_t, net_dm_trunc_len, payload_len);
- msg = nlmsg_new(net_dm_packet_report_size(payload_len,
- NET_DM_SKB_CB(skb)->reason),
- GFP_KERNEL);
+ msg = nlmsg_new(net_dm_packet_report_size(payload_len), GFP_KERNEL);
if (!msg)
goto out;
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 050a875d09c5..cf3b6b5d0b50 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -58,6 +58,7 @@
#include <linux/scatterlist.h>
#include <linux/errqueue.h>
#include <linux/prefetch.h>
+#include <linux/bitfield.h>
#include <linux/if_vlan.h>
#include <linux/mpls.h>
#include <linux/kcov.h>
@@ -72,6 +73,7 @@
#include <net/mptcp.h>
#include <net/mctp.h>
#include <net/page_pool.h>
+#include <net/dropreason.h>
#include <linux/uaccess.h>
#include <trace/events/skb.h>
@@ -122,11 +124,59 @@ EXPORT_SYMBOL(sysctl_max_skb_frags);
#undef FN
#define FN(reason) [SKB_DROP_REASON_##reason] = #reason,
-const char * const drop_reasons[] = {
+static const char * const drop_reasons[] = {
[SKB_CONSUMED] = "CONSUMED",
DEFINE_DROP_REASON(FN, FN)
};
-EXPORT_SYMBOL(drop_reasons);
+
+static const struct drop_reason_list drop_reasons_core = {
+ .reasons = drop_reasons,
+ .n_reasons = ARRAY_SIZE(drop_reasons),
+};
+
+const struct drop_reason_list __rcu *
+drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_NUM] = {
+ [SKB_DROP_REASON_SUBSYS_CORE] = RCU_INITIALIZER(&drop_reasons_core),
+};
+EXPORT_SYMBOL(drop_reasons_by_subsys);
+
+/**
+ * drop_reasons_register_subsys - register another drop reason subsystem
+ * @subsys: the subsystem to register, must not be the core
+ * @list: the list of drop reasons within the subsystem, must point to
+ * a statically initialized list
+ */
+void drop_reasons_register_subsys(enum skb_drop_reason_subsys subsys,
+ const struct drop_reason_list *list)
+{
+ if (WARN(subsys <= SKB_DROP_REASON_SUBSYS_CORE ||
+ subsys >= ARRAY_SIZE(drop_reasons_by_subsys),
+ "invalid subsystem %d\n", subsys))
+ return;
+
+ /* must point to statically allocated memory, so INIT is OK */
+ RCU_INIT_POINTER(drop_reasons_by_subsys[subsys], list);
+}
+EXPORT_SYMBOL_GPL(drop_reasons_register_subsys);
+
+/**
+ * drop_reasons_unregister_subsys - unregister a drop reason subsystem
+ * @subsys: the subsystem to remove, must not be the core
+ *
+ * Note: This will synchronize_rcu() to ensure no users when it returns.
+ */
+void drop_reasons_unregister_subsys(enum skb_drop_reason_subsys subsys)
+{
+ if (WARN(subsys <= SKB_DROP_REASON_SUBSYS_CORE ||
+ subsys >= ARRAY_SIZE(drop_reasons_by_subsys),
+ "invalid subsystem %d\n", subsys))
+ return;
+
+ RCU_INIT_POINTER(drop_reasons_by_subsys[subsys], NULL);
+
+ synchronize_rcu();
+}
+EXPORT_SYMBOL_GPL(drop_reasons_unregister_subsys);
/**
* skb_panic - private function for out-of-line support
@@ -984,7 +1034,10 @@ bool __kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason)
if (unlikely(!skb_unref(skb)))
return false;
- DEBUG_NET_WARN_ON_ONCE(reason <= 0 || reason >= SKB_DROP_REASON_MAX);
+ DEBUG_NET_WARN_ON_ONCE(reason == SKB_NOT_DROPPED_YET ||
+ u32_get_bits(reason,
+ SKB_DROP_REASON_SUBSYS_MASK) >=
+ SKB_DROP_REASON_SUBSYS_NUM);
if (reason == SKB_CONSUMED)
trace_consume_skb(skb, __builtin_return_address(0));
--
2.40.0
Powered by blists - more mailing lists