[PATCH v2 5/5] io_uring: add fgetxattr and getxattr support

[Stefan Roesch <shr@fb.com>]

This adds support to io_uring for the fgetxattr and getxattr API.

Signed-off-by: Stefan Roesch <shr@fb.com>
---
 fs/io_uring.c                 | 153 ++++++++++++++++++++++++++++++++++
 include/uapi/linux/io_uring.h |   2 +
 2 files changed, 155 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 9d977bf243fd..231a021d8eea 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1114,6 +1114,10 @@ static const struct io_op_def io_op_defs[] = {
 	[IORING_OP_MKDIRAT] = {},
 	[IORING_OP_SYMLINKAT] = {},
 	[IORING_OP_LINKAT] = {},
+	[IORING_OP_FGETXATTR] = {
+		.needs_file = 1
+	},
+	[IORING_OP_GETXATTR] = {},
 	[IORING_OP_FSETXATTR] = {
 		.needs_file = 1
 	},
@@ -3831,6 +3835,136 @@ static int io_renameat(struct io_kiocb *req, unsigned int issue_flags)
 	return 0;
 }
 
+static int __io_getxattr_prep(struct io_kiocb *req,
+			      const struct io_uring_sqe *sqe)
+{
+	struct io_xattr *ix = &req->xattr;
+	const char __user *name;
+	int ret;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (unlikely(sqe->ioprio))
+		return -EINVAL;
+	if (unlikely(req->flags & REQ_F_FIXED_FILE))
+		return -EBADF;
+
+	ix->filename = NULL;
+	ix->value = NULL;
+	name = u64_to_user_ptr(READ_ONCE(sqe->addr));
+	ix->ctx.value = u64_to_user_ptr(READ_ONCE(sqe->addr2));
+	ix->ctx.size = READ_ONCE(sqe->len);
+	ix->ctx.flags = READ_ONCE(sqe->xattr_flags);
+
+	if (ix->ctx.flags)
+		return -EINVAL;
+
+	ix->ctx.kname = kmalloc(XATTR_NAME_MAX + 1, GFP_KERNEL);
+	if (!ix->ctx.kname)
+		return -ENOMEM;
+
+	ret = strncpy_from_user(ix->ctx.kname, name, XATTR_NAME_MAX + 1);
+	if (!ret || ret == XATTR_NAME_MAX + 1)
+		ret = -ERANGE;
+	if (ret < 0) {
+		kfree(ix->ctx.kname);
+		return ret;
+	}
+
+	req->flags |= REQ_F_NEED_CLEANUP;
+	return 0;
+}
+
+static int io_fgetxattr_prep(struct io_kiocb *req,
+			     const struct io_uring_sqe *sqe)
+{
+	if (!req->file)
+		return -EBADF;
+
+	return __io_getxattr_prep(req, sqe);
+}
+
+static int io_getxattr_prep(struct io_kiocb *req,
+			    const struct io_uring_sqe *sqe)
+{
+	struct io_xattr *ix = &req->xattr;
+	const char __user *path;
+	int ret;
+
+	ret = __io_getxattr_prep(req, sqe);
+	if (ret)
+		return ret;
+
+	path = u64_to_user_ptr(READ_ONCE(sqe->addr3));
+
+	ix->filename = getname_flags(path, LOOKUP_FOLLOW, NULL);
+	if (IS_ERR(ix->filename)) {
+		ret = PTR_ERR(ix->filename);
+		ix->filename = NULL;
+	}
+
+	return ret;
+}
+
+static int io_fgetxattr(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_xattr *ix = &req->xattr;
+	int ret;
+
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		return -EAGAIN;
+
+	ret = do_getxattr(mnt_user_ns(req->file->f_path.mnt),
+			req->file->f_path.dentry,
+			ix->ctx.kname,
+			(void __user *)ix->ctx.value,
+			ix->ctx.size);
+
+	req->flags &= ~REQ_F_NEED_CLEANUP;
+	kfree(ix->ctx.kname);
+	if (ret < 0)
+		req_set_fail(req);
+
+	io_req_complete(req, ret);
+	return 0;
+}
+
+static int io_getxattr(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_xattr *ix = &req->xattr;
+	unsigned int lookup_flags = LOOKUP_FOLLOW;
+	struct path path;
+	int ret;
+
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		return -EAGAIN;
+
+retry:
+	ret = do_user_path_at_empty(AT_FDCWD, ix->filename, lookup_flags, &path);
+	putname(ix->filename);
+	if (!ret) {
+		ret = do_getxattr(mnt_user_ns(path.mnt),
+				  path.dentry,
+				  ix->ctx.kname,
+				  (void __user *)ix->ctx.value,
+				  ix->ctx.size);
+
+		path_put(&path);
+		if (retry_estale(ret, lookup_flags)) {
+			lookup_flags |= LOOKUP_REVAL;
+			goto retry;
+		}
+	}
+
+	req->flags &= ~REQ_F_NEED_CLEANUP;
+	kfree(ix->ctx.kname);
+	if (ret < 0)
+		req_set_fail(req);
+
+	io_req_complete(req, ret);
+	return 0;
+}
+
 static int __io_setxattr_prep(struct io_kiocb *req,
 			const struct io_uring_sqe *sqe,
 			struct user_namespace *user_ns)
@@ -6685,6 +6819,10 @@ static int io_req_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		return io_symlinkat_prep(req, sqe);
 	case IORING_OP_LINKAT:
 		return io_linkat_prep(req, sqe);
+	case IORING_OP_FGETXATTR:
+		return io_fgetxattr_prep(req, sqe);
+	case IORING_OP_GETXATTR:
+		return io_getxattr_prep(req, sqe);
 	case IORING_OP_FSETXATTR:
 		return io_fsetxattr_prep(req, sqe);
 	case IORING_OP_SETXATTR:
@@ -6832,6 +6970,15 @@ static void io_clean_op(struct io_kiocb *req)
 			putname(req->hardlink.oldpath);
 			putname(req->hardlink.newpath);
 			break;
+
+		case IORING_OP_GETXATTR:
+			if (req->xattr.filename)
+				putname(req->xattr.filename);
+			fallthrough;
+		case IORING_OP_FGETXATTR:
+			kfree(req->xattr.ctx.kname);
+			break;
+
 		case IORING_OP_SETXATTR:
 			if (req->xattr.filename)
 				putname(req->xattr.filename);
@@ -6983,6 +7130,12 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
 	case IORING_OP_LINKAT:
 		ret = io_linkat(req, issue_flags);
 		break;
+	case IORING_OP_FGETXATTR:
+		ret = io_fgetxattr(req, issue_flags);
+		break;
+	case IORING_OP_GETXATTR:
+		ret = io_getxattr(req, issue_flags);
+		break;
 	case IORING_OP_FSETXATTR:
 		ret = io_fsetxattr(req, issue_flags);
 		break;
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index dbf473900da2..cd9160272308 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -145,7 +145,9 @@ enum {
 	IORING_OP_MKDIRAT,
 	IORING_OP_SYMLINKAT,
 	IORING_OP_LINKAT,
+	IORING_OP_FGETXATTR,
 	IORING_OP_FSETXATTR,
+	IORING_OP_GETXATTR,
 	IORING_OP_SETXATTR,
 
 	/* this goes last, obviously */
-- 
2.30.2