[Linux-cachefs] [PATCH 11/16] CacheFiles: Permit an inode's security ID to be obtained [try #3]

[David Howells]

Permit an inode's security ID to be obtained by the CacheFiles module.  This is
then used as the SID with which files and directories will be created in the
cache.

Signed-Off-By: David Howells <dhowells at redhat.com>
---

 include/linux/security.h |   19 +++++++++++++++++++
 security/dummy.c         |    7 +++++++
 security/selinux/hooks.c |    9 +++++++++
 3 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index 194ef49..a54958a 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -414,6 +414,11 @@ struct request_sock;
  *	the size of the buffer required.
  *	Returns number of bytes used/required on success.
  *
+ * @inode_get_secid:
+ *	Retrieve the security ID from an inode.
+ *	@inode refers to the inode to get the security ID from.
+ *	@secid points the location in which to return the security ID.
+ *
  * Security hooks for file operations
  *
  * @file_permission:
@@ -1256,6 +1261,7 @@ struct security_operations {
   	int (*inode_getsecurity)(const struct inode *inode, const char *name, void *buffer, size_t size, int err);
   	int (*inode_setsecurity)(struct inode *inode, const char *name, const void *value, size_t size, int flags);
   	int (*inode_listsecurity)(struct inode *inode, char *buffer, size_t buffer_size);
+	int (*inode_get_secid)(struct inode *inode, u32 *secid);
 
 	int (*file_permission) (struct file * file, int mask);
 	int (*file_alloc_security) (struct file * file);
@@ -1818,6 +1824,13 @@ static inline int security_inode_listsecurity(struct inode *inode, char *buffer,
 	return security_ops->inode_listsecurity(inode, buffer, buffer_size);
 }
 
+static inline int security_inode_get_secid(struct inode *inode, u32 *secid)
+{
+	if (unlikely(IS_PRIVATE(inode)))
+		return 0;
+	return security_ops->inode_get_secid(inode, secid);
+}
+
 static inline int security_file_permission (struct file *file, int mask)
 {
 	return security_ops->file_permission (file, mask);
@@ -2518,6 +2531,12 @@ static inline int security_inode_listsecurity(struct inode *inode, char *buffer,
 	return 0;
 }
 
+static inline int security_inode_get_secid(struct inode *inode, u32 *secid)
+{
+	*secid = 0;
+	return 0;
+}
+
 static inline int security_file_permission (struct file *file, int mask)
 {
 	return 0;
diff --git a/security/dummy.c b/security/dummy.c
index 1a0be85..6be18fe 100644
--- a/security/dummy.c
+++ b/security/dummy.c
@@ -392,6 +392,12 @@ static int dummy_inode_listsecurity(struct inode *inode, char *buffer, size_t bu
 	return 0;
 }
 
+static int dummy_inode_get_secid(struct inode *inode, u32 *secid)
+{
+	*secid = 0;
+	return 0;
+}
+
 static const char *dummy_inode_xattr_getsuffix(void)
 {
 	return NULL;
@@ -1046,6 +1052,7 @@ void security_fixup_ops (struct security_operations *ops)
 	set_to_dummy_if_null(ops, inode_getsecurity);
 	set_to_dummy_if_null(ops, inode_setsecurity);
 	set_to_dummy_if_null(ops, inode_listsecurity);
+	set_to_dummy_if_null(ops, inode_get_secid);
 	set_to_dummy_if_null(ops, file_permission);
 	set_to_dummy_if_null(ops, file_alloc_security);
 	set_to_dummy_if_null(ops, file_free_security);
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 2c64ec8..34646f8 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2464,6 +2464,14 @@ static int selinux_inode_listsecurity(struct inode *inode, char *buffer, size_t
 	return len;
 }
 
+static int selinux_inode_get_secid(struct inode *inode, u32 *secid)
+{
+	struct inode_security_struct *isec = inode->i_security;
+
+	*secid = isec->sid;
+	return 0;
+}
+
 /* file security operations */
 
 static int selinux_file_permission(struct file *file, int mask)
@@ -4826,6 +4834,7 @@ static struct security_operations selinux_ops = {
 	.inode_getsecurity =            selinux_inode_getsecurity,
 	.inode_setsecurity =            selinux_inode_setsecurity,
 	.inode_listsecurity =           selinux_inode_listsecurity,
+	.inode_get_secid =		selinux_inode_get_secid,
 
 	.file_permission =		selinux_file_permission,
 	.file_alloc_security =		selinux_file_alloc_security,