diff mbox

[v5,9/9] selinux: Add a cache for quicker retreival of PKey SIDs

Message ID 1479843638-67136-10-git-send-email-danielj@mellanox.com (mailing list archive)
State Superseded
Headers show

Commit Message

Daniel Jurgens Nov. 22, 2016, 7:40 p.m. UTC
From: Daniel Jurgens <danielj@mellanox.com>

It is likely that the SID for the same PKey will be requested many
times. To reduce the time to modify QPs and process MADs use a cache to
store PKey SIDs.

This code is heavily based on the "netif" and "netport" concept
originally developed by James Morris <jmorris@redhat.com> and Paul Moore
<paul@paul-moore.com> (see security/selinux/netif.c and
security/selinux/netport.c for more information)

Signed-off-by: Daniel Jurgens <danielj@mellanox.com>

---
v2:
- Renamed the files to ibpkey. Paul Moore
- Fixed a braket indentation mismatch in sel_pkey_find. Yuval Shaia
- Change spin_lock_bh to spin_lock_irqsave to resolve HARDIRQ lockdep
  warning.  Dan Jurgens
---
 security/selinux/Makefile         |   2 +-
 security/selinux/hooks.c          |   7 +-
 security/selinux/ibpkey.c         | 245 ++++++++++++++++++++++++++++++++++++++
 security/selinux/include/ibpkey.h |  31 +++++
 security/selinux/include/objsec.h |   6 +
 5 files changed, 288 insertions(+), 3 deletions(-)
 create mode 100644 security/selinux/ibpkey.c
 create mode 100644 security/selinux/include/ibpkey.h

Comments

Daniel Jurgens Nov. 22, 2016, 11:21 p.m. UTC | #1
On 11/22/2016 4:53 PM, James Morris wrote:
> On Tue, 22 Nov 2016, Dan Jurgens wrote:
>
>> +static int sel_pkey_sid_slow(u64 subnet_prefix, u16 pkey_num, u32 *sid)
>> +{
>> +	int ret = -ENOMEM;
>> +	struct sel_pkey *pkey;
>> +	struct sel_pkey *new = NULL;
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&sel_pkey_lock, flags);
>> +	pkey = sel_pkey_find(subnet_prefix, pkey_num);
>> +	if (pkey) {
>> +		*sid = pkey->psec.sid;
>> +		spin_unlock_irqrestore(&sel_pkey_lock, flags);
>> +		return 0;
>> +	}
>> +
>> +	ret = security_pkey_sid(subnet_prefix, pkey_num, sid);
>> +	if (ret != 0)
>> +		goto out;
>> +
>> +	new = kzalloc(sizeof(*new), GFP_ATOMIC);
>> +	if (!new)
>> +		goto out;
>> +
>> +	new->psec.subnet_prefix = subnet_prefix;
>> +	new->psec.pkey = pkey_num;
>> +	new->psec.sid = *sid;
>> +	sel_pkey_insert(new);
>> +
>> +out:
>> +	spin_unlock_irqrestore(&sel_pkey_lock, flags);
>> +	if (unlikely(ret))
>> +		kfree(new);
>> +
>> +	return ret;
> The error handling is messed up here.
>
> You'll return 0 on kzalloc failure.
>
> Also, if security_pkey_sid fails, you'll attempt to kfree 'new', and you 
> don't need an unlikely() in a slow path.
>
>
Right.  I'll remove the if/kfree in the out path completely.  There's no way ret becomes non-zero after the kzalloc.  If the kzalloc fails I'll still have it return 0, the SID retrieved is valid, it just won't be added the cache so returning with an error is overkill.

Thank you for your review.
diff mbox

Patch

diff --git a/security/selinux/Makefile b/security/selinux/Makefile
index 3411c33..ff5895e 100644
--- a/security/selinux/Makefile
+++ b/security/selinux/Makefile
@@ -5,7 +5,7 @@ 
 obj-$(CONFIG_SECURITY_SELINUX) := selinux.o
 
 selinux-y := avc.o hooks.o selinuxfs.o netlink.o nlmsgtab.o netif.o \
-	     netnode.o netport.o exports.o \
+	     netnode.o netport.o ibpkey.o exports.o \
 	     ss/ebitmap.o ss/hashtab.o ss/symtab.o ss/sidtab.o ss/avtab.o \
 	     ss/policydb.o ss/services.o ss/conditional.o ss/mls.o ss/status.o
 
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 0954dfe..2fe4320 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -90,6 +90,7 @@ 
 #include "netif.h"
 #include "netnode.h"
 #include "netport.h"
+#include "ibpkey.h"
 #include "xfrm.h"
 #include "netlabel.h"
 #include "audit.h"
@@ -173,8 +174,10 @@  static int selinux_netcache_avc_callback(u32 event)
 
 static int selinux_lsm_notifier_avc_callback(u32 event)
 {
-	if (event == AVC_CALLBACK_RESET)
+	if (event == AVC_CALLBACK_RESET) {
+		sel_pkey_flush();
 		call_lsm_notifier(LSM_POLICY_CHANGE, NULL);
+	}
 
 	return 0;
 }
@@ -6094,7 +6097,7 @@  static int selinux_ib_pkey_access(void *ib_sec, u64 subnet_prefix, u16 pkey_val)
 	struct ib_security_struct *sec = ib_sec;
 	struct lsm_pkey_audit pkey;
 
-	err = security_pkey_sid(subnet_prefix, pkey_val, &sid);
+	err = sel_pkey_sid(subnet_prefix, pkey_val, &sid);
 
 	if (err)
 		return err;
diff --git a/security/selinux/ibpkey.c b/security/selinux/ibpkey.c
new file mode 100644
index 0000000..6e52c54
--- /dev/null
+++ b/security/selinux/ibpkey.c
@@ -0,0 +1,245 @@ 
+/*
+ * Pkey table
+ *
+ * SELinux must keep a mapping of Infinband PKEYs to labels/SIDs.  This
+ * mapping is maintained as part of the normal policy but a fast cache is
+ * needed to reduce the lookup overhead.
+ *
+ * This code is heavily based on the "netif" and "netport" concept originally
+ * developed by
+ * James Morris <jmorris@redhat.com> and
+ * Paul Moore <paul@paul-moore.com>
+ *   (see security/selinux/netif.c and security/selinux/netport.c for more
+ *   information)
+ *
+ */
+
+/*
+ * (c) Mellanox Technologies, 2016
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/rcupdate.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+
+#include "ibpkey.h"
+#include "objsec.h"
+
+#define SEL_PKEY_HASH_SIZE       256
+#define SEL_PKEY_HASH_BKT_LIMIT   16
+
+struct sel_pkey_bkt {
+	int size;
+	struct list_head list;
+};
+
+struct sel_pkey {
+	struct pkey_security_struct psec;
+	struct list_head list;
+	struct rcu_head rcu;
+};
+
+static LIST_HEAD(sel_pkey_list);
+static DEFINE_SPINLOCK(sel_pkey_lock);
+static struct sel_pkey_bkt sel_pkey_hash[SEL_PKEY_HASH_SIZE];
+
+/**
+ * sel_pkey_hashfn - Hashing function for the pkey table
+ * @pkey: pkey number
+ *
+ * Description:
+ * This is the hashing function for the pkey table, it returns the bucket
+ * number for the given pkey.
+ *
+ */
+static unsigned int sel_pkey_hashfn(u16 pkey)
+{
+	return (pkey & (SEL_PKEY_HASH_SIZE - 1));
+}
+
+/**
+ * sel_pkey_find - Search for a pkey record
+ * @subnet_prefix: subnet_prefix
+ * @pkey_num: pkey_num
+ *
+ * Description:
+ * Search the pkey table and return the matching record.  If an entry
+ * can not be found in the table return NULL.
+ *
+ */
+static struct sel_pkey *sel_pkey_find(u64 subnet_prefix, u16 pkey_num)
+{
+	unsigned int idx;
+	struct sel_pkey *pkey;
+
+	idx = sel_pkey_hashfn(pkey_num);
+	list_for_each_entry_rcu(pkey, &sel_pkey_hash[idx].list, list) {
+		if (pkey->psec.pkey == pkey_num &&
+		    pkey->psec.subnet_prefix == subnet_prefix)
+			return pkey;
+	}
+
+	return NULL;
+}
+
+/**
+ * sel_pkey_insert - Insert a new pkey into the table
+ * @pkey: the new pkey record
+ *
+ * Description:
+ * Add a new pkey record to the hash table.
+ *
+ */
+static void sel_pkey_insert(struct sel_pkey *pkey)
+{
+	unsigned int idx;
+
+	/* we need to impose a limit on the growth of the hash table so check
+	 * this bucket to make sure it is within the specified bounds
+	 */
+	idx = sel_pkey_hashfn(pkey->psec.pkey);
+	list_add_rcu(&pkey->list, &sel_pkey_hash[idx].list);
+	if (sel_pkey_hash[idx].size == SEL_PKEY_HASH_BKT_LIMIT) {
+		struct sel_pkey *tail;
+
+		tail = list_entry(
+			rcu_dereference_protected(
+				sel_pkey_hash[idx].list.prev,
+				lockdep_is_held(&sel_pkey_lock)),
+			struct sel_pkey, list);
+		list_del_rcu(&tail->list);
+		kfree_rcu(tail, rcu);
+	} else {
+		sel_pkey_hash[idx].size++;
+	}
+}
+
+/**
+ * sel_pkey_sid_slow - Lookup the SID of a pkey using the policy
+ * @subnet_prefix: subnet prefix
+ * @pkey_num: pkey number
+ * @sid: pkey SID
+ *
+ * Description:
+ * This function determines the SID of a pkey by querying the security
+ * policy.  The result is added to the pkey table to speedup future
+ * queries.  Returns zero on success, negative values on failure.
+ *
+ */
+static int sel_pkey_sid_slow(u64 subnet_prefix, u16 pkey_num, u32 *sid)
+{
+	int ret = -ENOMEM;
+	struct sel_pkey *pkey;
+	struct sel_pkey *new = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&sel_pkey_lock, flags);
+	pkey = sel_pkey_find(subnet_prefix, pkey_num);
+	if (pkey) {
+		*sid = pkey->psec.sid;
+		spin_unlock_irqrestore(&sel_pkey_lock, flags);
+		return 0;
+	}
+
+	ret = security_pkey_sid(subnet_prefix, pkey_num, sid);
+	if (ret != 0)
+		goto out;
+
+	new = kzalloc(sizeof(*new), GFP_ATOMIC);
+	if (!new)
+		goto out;
+
+	new->psec.subnet_prefix = subnet_prefix;
+	new->psec.pkey = pkey_num;
+	new->psec.sid = *sid;
+	sel_pkey_insert(new);
+
+out:
+	spin_unlock_irqrestore(&sel_pkey_lock, flags);
+	if (unlikely(ret))
+		kfree(new);
+
+	return ret;
+}
+
+/**
+ * sel_pkey_sid - Lookup the SID of a PKEY
+ * @subnet_prefix: subnet_prefix
+ * @pkey_num: pkey number
+ * @sid: pkey SID
+ *
+ * Description:
+ * This function determines the SID of a PKEY using the fastest method
+ * possible.  First the pkey table is queried, but if an entry can't be found
+ * then the policy is queried and the result is added to the table to speedup
+ * future queries.  Returns zero on success, negative values on failure.
+ *
+ */
+int sel_pkey_sid(u64 subnet_prefix, u16 pkey_num, u32 *sid)
+{
+	struct sel_pkey *pkey;
+
+	rcu_read_lock();
+	pkey = sel_pkey_find(subnet_prefix, pkey_num);
+	if (pkey) {
+		*sid = pkey->psec.sid;
+		rcu_read_unlock();
+		return 0;
+	}
+	rcu_read_unlock();
+
+	return sel_pkey_sid_slow(subnet_prefix, pkey_num, sid);
+}
+
+/**
+ * sel_pkey_flush - Flush the entire pkey table
+ *
+ * Description:
+ * Remove all entries from the pkey table
+ *
+ */
+void sel_pkey_flush(void)
+{
+	unsigned int idx;
+	struct sel_pkey *pkey, *pkey_tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&sel_pkey_lock, flags);
+	for (idx = 0; idx < SEL_PKEY_HASH_SIZE; idx++) {
+		list_for_each_entry_safe(pkey, pkey_tmp,
+					 &sel_pkey_hash[idx].list, list) {
+			list_del_rcu(&pkey->list);
+			kfree_rcu(pkey, rcu);
+		}
+		sel_pkey_hash[idx].size = 0;
+	}
+	spin_unlock_irqrestore(&sel_pkey_lock, flags);
+}
+
+static __init int sel_pkey_init(void)
+{
+	int iter;
+
+	if (!selinux_enabled)
+		return 0;
+
+	for (iter = 0; iter < SEL_PKEY_HASH_SIZE; iter++) {
+		INIT_LIST_HEAD(&sel_pkey_hash[iter].list);
+		sel_pkey_hash[iter].size = 0;
+	}
+
+	return 0;
+}
+
+subsys_initcall(sel_pkey_init);
diff --git a/security/selinux/include/ibpkey.h b/security/selinux/include/ibpkey.h
new file mode 100644
index 0000000..387885a
--- /dev/null
+++ b/security/selinux/include/ibpkey.h
@@ -0,0 +1,31 @@ 
+/*
+ * pkey table
+ *
+ * SELinux must keep a mapping of pkeys to labels/SIDs.  This
+ * mapping is maintained as part of the normal policy but a fast cache is
+ * needed to reduce the lookup overhead.
+ *
+ */
+
+/*
+ * (c) Mellanox Technologies, 2016
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef _SELINUX_IB_PKEY_H
+#define _SELINUX_IB_PKEY_H
+
+void sel_pkey_flush(void);
+
+int sel_pkey_sid(u64 subnet_prefix, u16 pkey, u32 *sid);
+
+#endif
diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index 8e7db43..4139f28 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -133,6 +133,12 @@  struct ib_security_struct {
 	u32 sid;        /* SID of the queue pair or MAD agent */
 };
 
+struct pkey_security_struct {
+	u64	subnet_prefix; /* Port subnet prefix */
+	u16	pkey;	/* PKey number */
+	u32	sid;	/* SID of pkey */
+};
+
 extern unsigned int selinux_checkreqprot;
 
 #endif /* _SELINUX_OBJSEC_H_ */