Btrfs: Add ACL support

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 261 insertions, 35 deletions

diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
index ff0fcc7..b192659 100644
--- a/fs/btrfs/acl.c
+++ b/fs/btrfs/acl.c
@@ -20,76 +20,302 @@
 #include <linux/string.h>
 #include <linux/xattr.h>
 #include <linux/posix_acl_xattr.h>
+#include <linux/posix_acl.h>
 #include <linux/sched.h>
+
 #include "ctree.h"
+#include "btrfs_inode.h"
 #include "xattr.h"
-#ifndef is_owner_or_cap
-#define is_owner_or_cap(inode)	\
-	((current->fsuid == (inode)->i_uid) || capable(CAP_FOWNER))
-#endif
+
+static void btrfs_update_cached_acl(struct inode *inode,
+				    struct posix_acl **p_acl,
+				    struct posix_acl *acl)
+{
+	spin_lock(&inode->i_lock);
+	if (*p_acl && *p_acl != BTRFS_ACL_NOT_CACHED)
+		posix_acl_release(*p_acl);
+	*p_acl = posix_acl_dup(acl);
+	spin_unlock(&inode->i_lock);
+}
+
+static struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
+{
+	int size, name_index;
+	char *value = NULL;
+	struct posix_acl *acl = NULL, **p_acl;
+
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		name_index = BTRFS_XATTR_INDEX_POSIX_ACL_ACCESS;
+		p_acl = &BTRFS_I(inode)->i_acl;
+		break;
+	case ACL_TYPE_DEFAULT:
+		name_index = BTRFS_XATTR_INDEX_POSIX_ACL_DEFAULT;
+		p_acl = &BTRFS_I(inode)->i_default_acl;
+		break;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+
+	spin_lock(&inode->i_lock);
+	if (*p_acl != BTRFS_ACL_NOT_CACHED)
+		acl = posix_acl_dup(*p_acl);
+	spin_unlock(&inode->i_lock);
+
+	if (acl)
+		return acl;
+
+
+	size = btrfs_xattr_get(inode, name_index, "", NULL, 0);
+	if (size > 0) {
+		value = kzalloc(size, GFP_NOFS);
+		if (!value)
+			return ERR_PTR(-ENOMEM);
+		size = btrfs_xattr_get(inode, name_index, "", value, size);
+		if (size > 0) {
+			acl = posix_acl_from_xattr(value, size);
+			btrfs_update_cached_acl(inode, p_acl, acl);
+		}
+		kfree(value);
+	} else if (size == -ENOENT) {
+		acl = NULL;
+		btrfs_update_cached_acl(inode, p_acl, acl);
+	}
+
+	return acl;
+}
+
+static int btrfs_xattr_get_acl(struct inode *inode, int type,
+			       void *value, size_t size)
+{
+	struct posix_acl *acl;
+	int ret = 0;
+
+	acl = btrfs_get_acl(inode, type);
+
+	if (IS_ERR(acl))
+		return PTR_ERR(acl);
+	if (acl == NULL)
+		return -ENODATA;
+	ret = posix_acl_to_xattr(acl, value, size);
+	posix_acl_release(acl);
+
+	return ret;
+}
+
+/*
+ * Needs to be called with fs_mutex held
+ */
+static int btrfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
+{
+	int ret, name_index = 0, size = 0;
+	struct posix_acl **p_acl;
+	char *value = NULL;
+	mode_t mode;
+
+	if (acl) {
+		ret = posix_acl_valid(acl);
+		if (ret < 0)
+			return ret;
+		ret = 0;
+	}
+
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		mode = inode->i_mode;
+		ret = posix_acl_equiv_mode(acl, &mode);
+		if (ret < 0)
+			return ret;
+		ret = 0;
+		inode->i_mode = mode;
+		name_index = BTRFS_XATTR_INDEX_POSIX_ACL_ACCESS;
+		p_acl = &BTRFS_I(inode)->i_acl;
+		break;
+	case ACL_TYPE_DEFAULT:
+		if (!S_ISDIR(inode->i_mode))
+			return acl ? -EINVAL : 0;
+		name_index = BTRFS_XATTR_INDEX_POSIX_ACL_DEFAULT;
+		p_acl = &BTRFS_I(inode)->i_default_acl;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (acl) {
+		size = posix_acl_xattr_size(acl->a_count);
+		value = kmalloc(size, GFP_NOFS);
+		if (!value) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		ret = posix_acl_to_xattr(acl, value, size);
+		if (ret < 0)
+			goto out;
+	}
+
+	ret = btrfs_xattr_set(inode, name_index, "", value, size, 0);
+
+out:
+	if (value)
+		kfree(value);
+
+	if (!ret)
+		btrfs_update_cached_acl(inode, p_acl, acl);
+
+	return ret;
+}
 
 static int btrfs_xattr_set_acl(struct inode *inode, int type,
 			       const void *value, size_t size)
 {
 	int ret = 0;
-	struct posix_acl *acl;
+	struct posix_acl *acl = NULL;
 
-	if (!is_owner_or_cap(inode))
-		return -EPERM;
 	if (value) {
 		acl = posix_acl_from_xattr(value, size);
 		if (acl == NULL) {
 			value = NULL;
 			size = 0;
 		} else if (IS_ERR(acl)) {
-			ret = PTR_ERR(acl);
-		} else {
-			ret = posix_acl_valid(acl);
-			posix_acl_release(acl);
+			return PTR_ERR(acl);
 		}
-		if (ret)
-			return ret;
 	}
-	return btrfs_xattr_set(inode, type, "", value, size, 0);
-}
 
-static int btrfs_xattr_get_acl(struct inode *inode, int type,
-			       void *value, size_t size)
-{
-	return btrfs_xattr_get(inode, type, "", value, size);
+	ret = btrfs_set_acl(inode, acl, type);
+
+	posix_acl_release(acl);
+
+	return ret;
 }
+
+
 static int btrfs_xattr_acl_access_get(struct inode *inode, const char *name,
 				      void *value, size_t size)
 {
-	if (*name != '\0')
-	       return -EINVAL;
-	return btrfs_xattr_get_acl(inode, BTRFS_XATTR_INDEX_POSIX_ACL_ACCESS,
-				   value, size);
+	return btrfs_xattr_get_acl(inode, ACL_TYPE_ACCESS, value, size);
 }
+
 static int btrfs_xattr_acl_access_set(struct inode *inode, const char *name,
 				      const void *value, size_t size, int flags)
 {
-	if (*name != '\0')
-	       return -EINVAL;
-	return btrfs_xattr_set_acl(inode, BTRFS_XATTR_INDEX_POSIX_ACL_ACCESS,
-				   value, size);
+	return btrfs_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 }
+
 static int btrfs_xattr_acl_default_get(struct inode *inode, const char *name,
 				       void *value, size_t size)
 {
-	if (*name != '\0')
-	       return -EINVAL;
-	return btrfs_xattr_get_acl(inode, BTRFS_XATTR_INDEX_POSIX_ACL_DEFAULT,
-				   value, size);
+	return btrfs_xattr_get_acl(inode, ACL_TYPE_DEFAULT, value, size);
 }
+
 static int btrfs_xattr_acl_default_set(struct inode *inode, const char *name,
 				       const void *value, size_t size, int flags)
 {
-	if (*name != '\0')
-	       return -EINVAL;
-	return btrfs_xattr_set_acl(inode, BTRFS_XATTR_INDEX_POSIX_ACL_DEFAULT,
-				   value, size);
+	return btrfs_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
+}
+
+int btrfs_check_acl(struct inode *inode, int mask)
+{
+	struct posix_acl *acl;
+	int error = -EAGAIN;
+
+	acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
+
+	if (IS_ERR(acl))
+		return PTR_ERR(acl);
+	if (acl) {
+		error = posix_acl_permission(inode, acl, mask);
+		posix_acl_release(acl);
+	}
+
+	return error;
+}
+
+/*
+ * btrfs_init_acl is already generally called under fs_mutex, so the locking
+ * stuff has been fixed to work with that.  If the locking stuff changes, we
+ * need to re-evaluate the acl locking stuff.
+ */
+int btrfs_init_acl(struct inode *inode, struct inode *dir)
+{
+	struct posix_acl *acl = NULL;
+	int ret = 0;
+
+	/* this happens with subvols */
+	if (!dir)
+		return 0;
+
+	if (!S_ISLNK(inode->i_mode)) {
+		if (IS_POSIXACL(dir)) {
+			acl = btrfs_get_acl(dir, ACL_TYPE_DEFAULT);
+			if (IS_ERR(acl))
+				return PTR_ERR(acl);
+		}
+
+		if (!acl)
+			inode->i_mode &= ~current->fs->umask;
+	}
+
+	if (IS_POSIXACL(dir) && acl) {
+		struct posix_acl *clone;
+		mode_t mode;
+
+		if (S_ISDIR(inode->i_mode)) {
+			ret = btrfs_set_acl(inode, acl, ACL_TYPE_DEFAULT);
+			if (ret)
+				goto failed;
+		}
+		clone = posix_acl_clone(acl, GFP_NOFS);
+		ret = -ENOMEM;
+		if (!clone)
+			goto failed;
+
+		mode = inode->i_mode;
+		ret = posix_acl_create_masq(clone, &mode);
+		if (ret >= 0) {
+			inode->i_mode = mode;
+			if (ret > 0) {
+				/* we need an acl */
+				ret = btrfs_set_acl(inode, clone,
+						    ACL_TYPE_ACCESS);
+			}
+		}
+	}
+failed:
+	posix_acl_release(acl);
+
+	return ret;
+}
+
+int btrfs_acl_chmod(struct inode *inode)
+{
+	struct posix_acl *acl, *clone;
+	int ret = 0;
+
+	if (S_ISLNK(inode->i_mode))
+		return -EOPNOTSUPP;
+
+	if (!IS_POSIXACL(inode))
+		return 0;
+
+	acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
+	if (IS_ERR(acl) || !acl)
+		return PTR_ERR(acl);
+
+	clone = posix_acl_clone(acl, GFP_KERNEL);
+	posix_acl_release(acl);
+	if (!clone)
+		return -ENOMEM;
+
+	ret = posix_acl_chmod_masq(clone, inode->i_mode);
+	if (!ret)
+		ret = btrfs_set_acl(inode, clone, ACL_TYPE_ACCESS);
+
+	posix_acl_release(clone);
+
+	return ret;
 }
+
 struct xattr_handler btrfs_xattr_acl_default_handler = {
 	.prefix = POSIX_ACL_XATTR_DEFAULT,
 	.list	= btrfs_xattr_generic_list,