[PATCH] Btrfs: support security xattr with SELinux enabled

[jim owens <jowens@xxxxxx>]

Add call to LSM security initialization and save
resulting security xattr for new inodes.

Add xattr support to symlink inode ops.

Set inode->i_op for existing special files.

Signed-off-by: jim owens <jowens@xxxxxx>
---
 fs/btrfs/inode.c |   23 +++++++++++++++++++----
 fs/btrfs/xattr.c |   32 ++++++++++++++++++++++++++++++++
 fs/btrfs/xattr.h |    2 ++
 3 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index cdb7011..dd6152a 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -91,6 +91,16 @@ static noinline int cow_file_range(struct inode *inode,
 				   u64 start, u64 end, int *page_started,
 				   unsigned long *nr_written, int unlock);

+static int btrfs_init_inode_security(struct inode *inode,  struct inode 
*dir)
+{
+	int err;
+
+	err = btrfs_init_acl(inode, dir);
+	if (!err)
+		err = btrfs_xattr_security_init(inode, dir);
+	return err;
+}
+
 /*
  * a very lame attempt at stopping writes when the FS is 85% full.  There
  * are countless ways this is incorrect, but it is better than nothing.
@@ -2039,6 +2049,7 @@ void btrfs_read_locked_inode(struct inode *inode)
 		inode->i_mapping->backing_dev_info = &root->fs_info->bdi;
 		break;
 	default:
+		inode->i_op = &btrfs_special_inode_operations;
 		init_special_inode(inode, inode->i_mode, rdev);
 		break;
 	}
@@ -3586,7 +3597,7 @@ static int btrfs_mknod(struct inode *dir, struct 
dentry *dentry,
 	if (IS_ERR(inode))
 		goto out_unlock;

-	err = btrfs_init_acl(inode, dir);
+	err = btrfs_init_inode_security(inode, dir);
 	if (err) {
 		drop_inode = 1;
 		goto out_unlock;
@@ -3649,7 +3660,7 @@ static int btrfs_create(struct inode *dir, struct 
dentry *dentry,
 	if (IS_ERR(inode))
 		goto out_unlock;

-	err = btrfs_init_acl(inode, dir);
+	err = btrfs_init_inode_security(inode, dir);
 	if (err) {
 		drop_inode = 1;
 		goto out_unlock;
@@ -3772,7 +3783,7 @@ static int btrfs_mkdir(struct inode *dir, struct 
dentry *dentry, int mode)

 	drop_on_err = 1;

-	err = btrfs_init_acl(inode, dir);
+	err = btrfs_init_inode_security(inode, dir);
 	if (err)
 		goto out_fail;

@@ -4733,7 +4744,7 @@ static int btrfs_symlink(struct inode *dir, struct 
dentry *dentry,
 	if (IS_ERR(inode))
 		goto out_unlock;

-	err = btrfs_init_acl(inode, dir);
+	err = btrfs_init_inode_security(inode, dir);
 	if (err) {
 		drop_inode = 1;
 		goto out_unlock;
@@ -5032,4 +5043,8 @@ static struct inode_operations 
btrfs_symlink_inode_operations = {
 	.follow_link	= page_follow_link_light,
 	.put_link	= page_put_link,
 	.permission	= btrfs_permission,
+	.setxattr	= btrfs_setxattr,
+	.getxattr	= btrfs_getxattr,
+	.listxattr	= btrfs_listxattr,
+	.removexattr	= btrfs_removexattr,
 };
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index 7f332e2..02195f4 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -21,6 +21,7 @@
 #include <linux/slab.h>
 #include <linux/rwsem.h>
 #include <linux/xattr.h>
+#include <linux/security.h>
 #include "ctree.h"
 #include "btrfs_inode.h"
 #include "transaction.h"
@@ -320,3 +321,34 @@ int btrfs_removexattr(struct dentry *dentry, const 
char *name)
 		return -EOPNOTSUPP;
 	return __btrfs_setxattr(dentry->d_inode, name, NULL, 0, XATTR_REPLACE);
 }
+
+int btrfs_xattr_security_init(struct inode *inode, struct inode *dir)
+{
+	int err;
+	size_t len;
+	void *value;
+	char *suffix;
+	char *name;
+
+	err = security_inode_init_security(inode, dir, &suffix, &value, &len);
+	if (err) {
+		if (err == -EOPNOTSUPP)
+			return 0;
+		return err;
+	}
+
+	name = kmalloc(XATTR_SECURITY_PREFIX_LEN + strlen(suffix) + 1,
+		       GFP_NOFS);
+	if (!name) {
+		err = -ENOMEM;
+	} else {
+		strcpy(name, XATTR_SECURITY_PREFIX);
+		strcpy(name + XATTR_SECURITY_PREFIX_LEN, suffix);
+		err = __btrfs_setxattr(inode, name, value, len, 0);
+		kfree(name);
+	}
+
+	kfree(suffix);
+	kfree(value);
+	return err;
+}
diff --git a/fs/btrfs/xattr.h b/fs/btrfs/xattr.h
index 5b1d08f..c71e9c3 100644
--- a/fs/btrfs/xattr.h
+++ b/fs/btrfs/xattr.h
@@ -36,4 +36,6 @@ extern int btrfs_setxattr(struct dentry *dentry, const 
char *name,
 		const void *value, size_t size, int flags);
 extern int btrfs_removexattr(struct dentry *dentry, const char *name);

+extern int btrfs_xattr_security_init(struct inode *inode, struct inode 
*dir);
+
 #endif /* __XATTR__ */
--
1.5.4.3

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