fs: add generic xattr_acl handlers

With the ->set_acl inode operation we can implement the Posix ACL
xattr handlers in generic code instead of duplicating them all
over the tree.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 105 insertions, 0 deletions

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 30524de49a6b..e699b076cdd8 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -17,6 +17,7 @@
 #include <linux/sched.h>
 #include <linux/posix_acl.h>
 #include <linux/posix_acl_xattr.h>
+#include <linux/xattr.h>
 #include <linux/export.h>
 #include <linux/user_namespace.h>
 
@@ -611,3 +612,104 @@ posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
         return real_size;
 }
 EXPORT_SYMBOL (posix_acl_to_xattr);
+
+static int
+posix_acl_xattr_get(struct dentry *dentry, const char *name,
+                void *value, size_t size, int type)
+{
+        struct posix_acl *acl;
+        int error;
+
+        if (!IS_POSIXACL(dentry->d_inode))
+                return -EOPNOTSUPP;
+        if (S_ISLNK(dentry->d_inode->i_mode))
+                return -EOPNOTSUPP;
+
+        acl = get_acl(dentry->d_inode, type);
+        if (IS_ERR(acl))
+                return PTR_ERR(acl);
+        if (acl == NULL)
+                return -ENODATA;
+
+        error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
+        posix_acl_release(acl);
+
+        return error;
+}
+
+static int
+posix_acl_xattr_set(struct dentry *dentry, const char *name,
+                const void *value, size_t size, int flags, int type)
+{
+        struct inode *inode = dentry->d_inode;
+        struct posix_acl *acl = NULL;
+        int ret;
+
+        if (!IS_POSIXACL(inode))
+                return -EOPNOTSUPP;
+        if (!inode->i_op->set_acl)
+                return -EOPNOTSUPP;
+
+        if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
+                return value ? -EACCES : 0;
+        if (!inode_owner_or_capable(inode))
+                return -EPERM;
+
+        if (value) {
+                acl = posix_acl_from_xattr(&init_user_ns, value, size);
+                if (IS_ERR(acl))
+                        return PTR_ERR(acl);
+
+                if (acl) {
+                        ret = posix_acl_valid(acl);
+                        if (ret)
+                                goto out;
+                }
+        }
+
+        ret = inode->i_op->set_acl(inode, acl, type);
+out:
+        posix_acl_release(acl);
+        return ret;
+}
+
+static size_t
+posix_acl_xattr_list(struct dentry *dentry, char *list, size_t list_size,
+                const char *name, size_t name_len, int type)
+{
+        const char *xname;
+        size_t size;
+
+        if (!IS_POSIXACL(dentry->d_inode))
+                return -EOPNOTSUPP;
+        if (S_ISLNK(dentry->d_inode->i_mode))
+                return -EOPNOTSUPP;
+
+        if (type == ACL_TYPE_ACCESS)
+                xname = POSIX_ACL_XATTR_ACCESS;
+        else
+                xname = POSIX_ACL_XATTR_DEFAULT;
+
+        size = strlen(xname) + 1;
+        if (list && size <= list_size)
+                memcpy(list, xname, size);
+        return size;
+}
+
+const struct xattr_handler posix_acl_access_xattr_handler = {
+        .prefix = POSIX_ACL_XATTR_ACCESS,
+        .flags = ACL_TYPE_ACCESS,
+        .list = posix_acl_xattr_list,
+        .get = posix_acl_xattr_get,
+        .set = posix_acl_xattr_set,
+};
+EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
+
+const struct xattr_handler posix_acl_default_xattr_handler = {
+        .prefix = POSIX_ACL_XATTR_DEFAULT,
+        .flags = ACL_TYPE_DEFAULT,
+        .list = posix_acl_xattr_list,
+        .get = posix_acl_xattr_get,
+        .set = posix_acl_xattr_set,
+};
+EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
diff --git a/include/linux/posix_acl_xattr.h b/include/linux/posix_acl_xattr.h
index ad93ad0f1db0..6f14ee295822 100644
--- a/include/linux/posix_acl_xattr.h
+++ b/include/linux/posix_acl_xattr.h
@@ -69,4 +69,7 @@ struct posix_acl *posix_acl_from_xattr(struct user_namespace *user_ns,
 int posix_acl_to_xattr(struct user_namespace *user_ns,
                        const struct posix_acl *acl, void *buffer, size_t size);
 
+extern const struct xattr_handler posix_acl_access_xattr_handler;
+extern const struct xattr_handler posix_acl_default_xattr_handler;
+
 #endif  /* _POSIX_ACL_XATTR_H */