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Subject[RFC v3 04/10] snet: introduce snet_event
Date
This patch adds the snet's subsystem responsive of managing events

snet is using the word 'event' for a couple of values [syscall, protocol].
For example, [listen, tcp] or [sendmsg, dccp] are events.

This patch introduces a hastable 'event_hash' and operations (add/remove/search..)
in order to manage which events have to be protected.
With the help of the communication's subsystem, managing orders are coming from
userspace.

Signed-off-by: Samir Bellabes <sam@synack.fr>
---
security/snet/snet_event.c | 201 ++++++++++++++++++++++++++++++++++++++++++++
security/snet/snet_event.h | 21 +++++
2 files changed, 222 insertions(+), 0 deletions(-)
create mode 100644 security/snet/snet_event.c
create mode 100644 security/snet/snet_event.h
diff --git a/security/snet/snet_event.c b/security/snet/snet_event.c
new file mode 100644
index 0000000..7146d5a
--- /dev/null
+++ b/security/snet/snet_event.c
@@ -0,0 +1,201 @@
+#include <linux/spinlock.h>
+#include <linux/list.h>
+#include <linux/jhash.h>
+#include <linux/slab.h>
+#include <linux/netlink.h>
+#include <linux/snet.h>
+#include "snet_event.h"
+#include "snet_netlink.h"
+#include "snet_utils.h"
+
+static struct list_head *snet_evh;
+static DEFINE_RWLOCK(snet_evh_lock);
+
+struct snet_event_entry {
+ struct list_head list;
+ struct snet_event se;
+};
+
+static struct kmem_cache *snet_event_entry_cachep;
+
+/* lookup for a snet_evh - before using this function, lock snet_evh_lock */
+static struct snet_event_entry *__snet_event_lookup(const enum snet_syscall syscall,
+ const u8 protocol)
+{
+ unsigned int h = 0;
+ struct list_head *l;
+ struct snet_event_entry *s;
+
+ /* computing its hash value */
+ h = jhash_2words(syscall, protocol, 0) % snet_evh_size;
+ l = &snet_evh[h];
+
+ list_for_each_entry(s, l, list) {
+ if ((s->se.protocol == protocol) &&
+ (s->se.syscall == syscall)) {
+ return s;
+ }
+ }
+ return NULL;
+}
+
+int snet_event_fill_info(struct sk_buff *skb, struct netlink_callback *cb)
+{
+ unsigned int i = 0, n = 0;
+ int ret = -1;
+ unsigned hashs_to_skip = cb->args[0];
+ unsigned events_to_skip = cb->args[1];
+ struct list_head *l;
+ struct snet_event_entry *s;
+
+ read_lock_bh(&snet_evh_lock);
+
+ for (i = 0; i < snet_evh_size; i++) {
+ if (i < hashs_to_skip)
+ continue;
+ l = &snet_evh[i];
+ n = 0;
+ list_for_each_entry(s, l, list) {
+ if (++n < events_to_skip)
+ continue;
+ ret = snet_nl_list_fill_info(skb,
+ NETLINK_CB(cb->skb).pid,
+ cb->nlh->nlmsg_seq,
+ NLM_F_MULTI,
+ s->se.protocol,
+ s->se.syscall);
+ if (ret < 0)
+ goto errout;
+ }
+ }
+
+errout:
+ read_unlock_bh(&snet_evh_lock);
+
+ cb->args[0] = i;
+ cb->args[1] = n;
+ return skb->len;
+}
+
+/*
+ * check if a event is registered or not
+ * return 1 if event is registered, 0 if not
+ */
+int snet_event_is_registered(const enum snet_syscall syscall, const u8 protocol)
+{
+ int ret = 0;
+
+ read_lock_bh(&snet_evh_lock);
+ if (__snet_event_lookup(syscall, protocol) != NULL)
+ ret = 1;
+ read_unlock_bh(&snet_evh_lock);
+ return ret;
+}
+
+/* adding a event */
+int snet_event_insert(const enum snet_syscall syscall, const u8 protocol)
+{
+ struct snet_event_entry *data = NULL;
+ unsigned int h = 0;
+ int err = 0;
+
+ data = kmem_cache_zalloc(snet_event_entry_cachep, GFP_KERNEL);
+ if (!data) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ write_lock_bh(&snet_evh_lock);
+ /* check if event is already registered */
+ if (__snet_event_lookup(syscall, protocol) != NULL) {
+ write_unlock_bh(&snet_evh_lock);
+ kmem_cache_free(snet_event_entry_cachep, data);
+ err = -EINVAL;
+ goto out;
+ }
+
+ data->se.syscall = syscall;
+ data->se.protocol = protocol;
+ INIT_LIST_HEAD(&(data->list));
+ h = jhash_2words(data->se.syscall, data->se.protocol, 0) % snet_evh_size;
+ list_add_tail(&data->list, &snet_evh[h]);
+ write_unlock_bh(&snet_evh_lock);
+ pr_debug("[%u]=(syscall=%s, protocol=%u)\n",
+ h, snet_syscall_name(syscall), protocol);
+out:
+ return err;
+}
+
+/* removing a event */
+int snet_event_remove(const enum snet_syscall syscall, const u8 protocol)
+{
+ struct snet_event_entry *data = NULL;
+
+ write_lock_bh(&snet_evh_lock);
+ data = __snet_event_lookup(syscall, protocol);
+ if (data == NULL) {
+ write_unlock_bh(&snet_evh_lock);
+ return -EINVAL;
+ }
+ pr_debug("(syscall=%s, protocol=%u)\n",
+ snet_syscall_name(syscall), protocol);
+ list_del(&data->list);
+ write_unlock_bh(&snet_evh_lock);
+ kmem_cache_free(snet_event_entry_cachep, data);
+ return 0;
+}
+
+/* flushing all events */
+void snet_event_flush(void)
+{
+ unsigned int i = 0;
+
+ write_lock_bh(&snet_evh_lock);
+ for (i = 0; i < snet_evh_size; i++) {
+ struct snet_event_entry *data, *tmp;
+ list_for_each_entry_safe(data, tmp, &snet_evh[i], list) {
+ list_del(&data->list);
+ kmem_cache_free(snet_event_entry_cachep, data);
+ }
+ }
+ write_unlock_bh(&snet_evh_lock);
+ return;
+}
+
+/* init function */
+int snet_event_init(void)
+{
+ int err = 0, i = 0;
+
+ if (snet_evh_size == 0) {
+ printk(KERN_ERR "snet: bad snet_evh_size value\n");
+ err = -EINVAL;
+ goto out;
+ }
+
+ snet_evh = kzalloc(sizeof(struct list_head) * snet_evh_size,
+ GFP_KERNEL);
+ if (!snet_evh) {
+ printk(KERN_WARNING
+ "snet: can't alloc memory for snet_evh\n");
+ err = -ENOMEM;
+ goto out;
+ }
+
+ for (i = 0; i < snet_evh_size; i++)
+ INIT_LIST_HEAD(&snet_evh[i]);
+
+ /* snet_event_entry_cachep is not destroyed */
+ snet_event_entry_cachep = kmem_cache_create("snet_event_entry",
+ sizeof(struct snet_event_entry),
+ 0, SLAB_PANIC, NULL);
+out:
+ return err;
+}
+
+/* exit function */
+void snet_event_exit(void)
+{
+ kfree(snet_evh);
+ snet_evh = NULL;
+}
diff --git a/security/snet/snet_event.h b/security/snet/snet_event.h
new file mode 100644
index 0000000..fa991c7
--- /dev/null
+++ b/security/snet/snet_event.h
@@ -0,0 +1,21 @@
+#ifndef _SNET_EVENT_H
+#define _SNET_EVENT_H
+
+#include <linux/skbuff.h>
+
+extern unsigned int snet_evh_size;
+
+/* manipulate the events hash table */
+int snet_event_fill_info(struct sk_buff *skb, struct netlink_callback *cb);
+int snet_event_is_registered(const enum snet_syscall syscall, const u8 protocol);
+int snet_event_insert(const enum snet_syscall syscall, const u8 protocol);
+int snet_event_remove(const enum snet_syscall syscall, const u8 protocol);
+void snet_event_flush(void);
+void snet_event_dumpall(void);
+
+/* init function */
+int snet_event_init(void);
+/* exit funtion */
+void snet_event_exit(void);
+
+#endif /* _SNET_EVENT_H */
--
1.7.4.1


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