Commit 5f8d28f6 authored by Casey Schaufler's avatar Casey Schaufler Committed by Paul Moore
Browse files

lsm: infrastructure management of the key security blob 



Move management of the key->security blob out of the individual security
modules and into the security infrastructure. Instead of allocating the
blobs from within the modules the modules tell the infrastructure how
much space is required, and the space is allocated there.  There are
no existing modules that require a key_free hook, so the call to it and
the definition for it have been removed.

Signed-off-by: default avatarCasey Schaufler <casey@schaufler-ca.com>
Reviewed-by: default avatarJohn Johansen <john.johansen@canonical.com>
[PM: subject tweak]
Signed-off-by: default avatarPaul Moore <paul@paul-moore.com>
parent 2aff9d20

include/linux/lsm_hook_defs.h

+0 −1
Original line number Diff line number Diff line
@@ -403,7 +403,6 @@ LSM_HOOK(int, 0, xfrm_decode_session, struct sk_buff *skb, u32 *secid, 
#ifdef CONFIG_KEYS

LSM_HOOK(int, 0, key_alloc, struct key *key, const struct cred *cred,

	 unsigned long flags)

LSM_HOOK(void, LSM_RET_VOID, key_free, struct key *key)

LSM_HOOK(int, 0, key_permission, key_ref_t key_ref, const struct cred *cred,

	 enum key_need_perm need_perm)

LSM_HOOK(int, 0, key_getsecurity, struct key *key, char **buffer)

include/linux/lsm_hooks.h

+1 −0
Original line number Diff line number Diff line
@@ -76,6 +76,7 @@ struct lsm_blob_sizes { 
	int	lbs_sock;

	int	lbs_superblock;

	int	lbs_ipc;

	int	lbs_key;

	int	lbs_msg_msg;

	int	lbs_task;

	int	lbs_xattr_count; /* number of xattr slots in new_xattrs array */

security/security.c

+37 −2
Original line number Diff line number Diff line
@@ -227,6 +227,7 @@ static void __init lsm_set_blob_sizes(struct lsm_blob_sizes *needed) 
		blob_sizes.lbs_inode = sizeof(struct rcu_head);

	lsm_set_blob_size(&needed->lbs_inode, &blob_sizes.lbs_inode);

	lsm_set_blob_size(&needed->lbs_ipc, &blob_sizes.lbs_ipc);

	lsm_set_blob_size(&needed->lbs_key, &blob_sizes.lbs_key);

	lsm_set_blob_size(&needed->lbs_msg_msg, &blob_sizes.lbs_msg_msg);

	lsm_set_blob_size(&needed->lbs_sock, &blob_sizes.lbs_sock);

	lsm_set_blob_size(&needed->lbs_superblock, &blob_sizes.lbs_superblock);
@@ -402,6 +403,9 @@ static void __init ordered_lsm_init(void) 
	init_debug("file blob size       = %d\n", blob_sizes.lbs_file);

	init_debug("inode blob size      = %d\n", blob_sizes.lbs_inode);

	init_debug("ipc blob size        = %d\n", blob_sizes.lbs_ipc);

#ifdef CONFIG_KEYS

	init_debug("key blob size        = %d\n", blob_sizes.lbs_key);

#endif /* CONFIG_KEYS */

	init_debug("msg_msg blob size    = %d\n", blob_sizes.lbs_msg_msg);

	init_debug("sock blob size       = %d\n", blob_sizes.lbs_sock);

	init_debug("superblock blob size = %d\n", blob_sizes.lbs_superblock);
@@ -718,6 +722,29 @@ static int lsm_ipc_alloc(struct kern_ipc_perm *kip) 
	return 0;

}



#ifdef CONFIG_KEYS

/**

 * lsm_key_alloc - allocate a composite key blob

 * @key: the key that needs a blob

 *

 * Allocate the key blob for all the modules

 *

 * Returns 0, or -ENOMEM if memory can't be allocated.

 */

static int lsm_key_alloc(struct key *key)

{

	if (blob_sizes.lbs_key == 0) {

		key->security = NULL;

		return 0;

	}



	key->security = kzalloc(blob_sizes.lbs_key, GFP_KERNEL);

	if (key->security == NULL)

		return -ENOMEM;

	return 0;

}

#endif /* CONFIG_KEYS */



/**

 * lsm_msg_msg_alloc - allocate a composite msg_msg blob

 * @mp: the msg_msg that needs a blob
@@ -5316,7 +5343,14 @@ EXPORT_SYMBOL(security_skb_classify_flow); 
int security_key_alloc(struct key *key, const struct cred *cred,

		       unsigned long flags)

{

	return call_int_hook(key_alloc, key, cred, flags);

	int rc = lsm_key_alloc(key);



	if (unlikely(rc))

		return rc;

	rc = call_int_hook(key_alloc, key, cred, flags);

	if (unlikely(rc))

		security_key_free(key);

	return rc;

}



/**
@@ -5327,7 +5361,8 @@ int security_key_alloc(struct key *key, const struct cred *cred, 
 */

void security_key_free(struct key *key)

{

	call_void_hook(key_free, key);

	kfree(key->security);

	key->security = NULL;

}



/**

security/selinux/hooks.c

+4 −17
Original line number Diff line number Diff line
@@ -6663,11 +6663,7 @@ static int selinux_key_alloc(struct key *k, const struct cred *cred, 
			     unsigned long flags)

{

	const struct task_security_struct *tsec;

	struct key_security_struct *ksec;



	ksec = kzalloc(sizeof(struct key_security_struct), GFP_KERNEL);

	if (!ksec)

		return -ENOMEM;

	struct key_security_struct *ksec = selinux_key(k);



	tsec = selinux_cred(cred);

	if (tsec->keycreate_sid)
@@ -6675,18 +6671,9 @@ static int selinux_key_alloc(struct key *k, const struct cred *cred, 
	else

		ksec->sid = tsec->sid;



	k->security = ksec;

	return 0;

}



static void selinux_key_free(struct key *k)

{

	struct key_security_struct *ksec = k->security;



	k->security = NULL;

	kfree(ksec);

}



static int selinux_key_permission(key_ref_t key_ref,

				  const struct cred *cred,

				  enum key_need_perm need_perm)
@@ -6727,14 +6714,14 @@ static int selinux_key_permission(key_ref_t key_ref, 


	sid = cred_sid(cred);

	key = key_ref_to_ptr(key_ref);

	ksec = key->security;

	ksec = selinux_key(key);



	return avc_has_perm(sid, ksec->sid, SECCLASS_KEY, perm, NULL);

}



static int selinux_key_getsecurity(struct key *key, char **_buffer)

{

	struct key_security_struct *ksec = key->security;

	struct key_security_struct *ksec = selinux_key(key);

	char *context = NULL;

	unsigned len;

	int rc;
@@ -6986,6 +6973,7 @@ struct lsm_blob_sizes selinux_blob_sizes __ro_after_init = { 
	.lbs_file = sizeof(struct file_security_struct),

	.lbs_inode = sizeof(struct inode_security_struct),

	.lbs_ipc = sizeof(struct ipc_security_struct),

	.lbs_key = sizeof(struct key_security_struct),

	.lbs_msg_msg = sizeof(struct msg_security_struct),

	.lbs_sock = sizeof(struct sk_security_struct),

	.lbs_superblock = sizeof(struct superblock_security_struct),
@@ -7324,7 +7312,6 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { 
#endif



#ifdef CONFIG_KEYS

	LSM_HOOK_INIT(key_free, selinux_key_free),

	LSM_HOOK_INIT(key_permission, selinux_key_permission),

	LSM_HOOK_INIT(key_getsecurity, selinux_key_getsecurity),

#ifdef CONFIG_KEY_NOTIFICATIONS

security/selinux/include/objsec.h

+7 −0
Original line number Diff line number Diff line
@@ -195,6 +195,13 @@ selinux_superblock(const struct super_block *superblock) 
	return superblock->s_security + selinux_blob_sizes.lbs_superblock;

}



#ifdef CONFIG_KEYS

static inline struct key_security_struct *selinux_key(const struct key *key)

{

	return key->security + selinux_blob_sizes.lbs_key;

}

#endif /* CONFIG_KEYS */



static inline struct sk_security_struct *selinux_sock(const struct sock *sock)

{

	return sock->sk_security + selinux_blob_sizes.lbs_sock;