[PATCH v7 0/5] io_uring: add xattr support

[PATCH v7 0/5] io_uring: add xattr support

[Stefan Roesch]

This adds the xattr support to io_uring. The intent is to have a more
complete support for file operations in io_uring.

This change adds support for the following functions to io_uring:
- fgetxattr
- fsetxattr
- getxattr
- setxattr

Patch 1: fs: split off do_user_path_at_empty from user_path_at_empty()
  This splits off a new function do_user_path_at_empty from
  user_path_at_empty that is based on filename and not on a
  user-specified string.

Patch 2: fs: split off setxattr_copy and do_setxattr function from setxattr
  Split off the setup part of the setxattr function in the setxattr_copy
  function. Split off the processing part in do_setxattr.

Patch 3: fs: split off do_getxattr from getxattr
  Split of the do_getxattr part from getxattr. This will
  allow it to be invoked it from io_uring.

Patch 4: io_uring: add fsetxattr and setxattr support
  This adds new functions to support the fsetxattr and setxattr
  functions.

Patch 5: io_uring: add fgetxattr and getxattr support
  This adds new functions to support the fgetxattr and getxattr
  functions.


There are two additional patches:
  liburing: Add support for xattr api's.
            This also includes the tests for the new code.
  xfstests: Add support for io_uring xattr support.


V7: - split off setxattr in two functions as recommeneded by
      Christian.
V6: - reverted addition of kname array to xattr_ctx structure
      Adding the kname array increases the io_kiocb beyond 64 bytes
      (increases it to 224 bytes). We try hard to limit it to 64 bytes.
      Keeping the original interface also is a bit more efficient.
    - addressed Pavel's reordering comment
    - addressed Pavel's putname comment
    - addressed Pavel's kvfree comment
    - rebased on for-5.17/io_uring-getdents64
V5: - add kname array to xattr_ctx structure
V4: - rebased patch series
V3: - remove req->file checks in prep functions
    - change size parameter in do_xattr
V2: - split off function do_user_path_empty instead of changing
      the function signature of user_path_at
    - Fix datatype size problem in do_getxattr


Stefan Roesch (5):
  fs: split off do_user_path_at_empty from user_path_at_empty()
  fs: split off setxattr_copy and do_setxattr function from setxattr
  fs: split off do_getxattr from getxattr
  io_uring: add fsetxattr and setxattr support
  io_uring: add fgetxattr and getxattr support

 fs/internal.h                 |  25 +++
 fs/io_uring.c                 | 315 ++++++++++++++++++++++++++++++++++
 fs/namei.c                    |  10 +-
 fs/xattr.c                    | 119 +++++++++----
 include/linux/namei.h         |   2 +
 include/uapi/linux/io_uring.h |   8 +-
 6 files changed, 442 insertions(+), 37 deletions(-)


base-commit: b4518682080d3a1cdd6ea45a54ff6772b8b2797a
-- 
2.30.2

[PATCH v7 1/5] fs: split off do_user_path_at_empty from user_path_at_empty()

[Stefan Roesch]

This splits off a do_user_path_at_empty function from the
user_path_at_empty_function. This is required so it can be
called from io_uring.

Signed-off-by: Stefan Roesch <shr@fb.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
---
 fs/namei.c            | 10 ++++++++--
 include/linux/namei.h |  2 ++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 1f9d2187c765..d988e241b32c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2794,12 +2794,18 @@ int path_pts(struct path *path)
 }
 #endif
 
+int do_user_path_at_empty(int dfd, struct filename *filename, unsigned int flags,
+		       struct path *path)
+{
+	return filename_lookup(dfd, filename, flags, path, NULL);
+}
+
 int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
-		 struct path *path, int *empty)
+		struct path *path, int *empty)
 {
 	struct filename *filename = getname_flags(name, flags, empty);
-	int ret = filename_lookup(dfd, filename, flags, path, NULL);
 
+	int ret = do_user_path_at_empty(dfd, filename, flags, path);
 	putname(filename);
 	return ret;
 }
diff --git a/include/linux/namei.h b/include/linux/namei.h
index e89329bb3134..8f3ef38c057b 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -49,6 +49,8 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT};
 
 extern int path_pts(struct path *path);
 
+extern int do_user_path_at_empty(int dfd, struct filename *filename,
+				unsigned int flags, struct path *path);
 extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
 
 static inline int user_path_at(int dfd, const char __user *name, unsigned flags,
-- 
2.30.2

[PATCH v7 2/5] fs: split off setxattr_copy and do_setxattr function from setxattr

[Stefan Roesch]

This splits of the setup part of the function
setxattr in its own dedicated function called
setxattr_copy. In addition it also exposes a
new function called do_setxattr for making the
setxattr call.

This makes it possible to call these two functions
from io_uring in the processing of an xattr request.

Signed-off-by: Stefan Roesch <shr@fb.com>
---
 fs/internal.h | 19 +++++++++++
 fs/xattr.c    | 87 ++++++++++++++++++++++++++++++++++++++-------------
 2 files changed, 84 insertions(+), 22 deletions(-)

diff --git a/fs/internal.h b/fs/internal.h
index 432ea3ce76ec..28b9f947f26e 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -202,3 +202,22 @@ struct linux_dirent64;
 
 int vfs_getdents(struct file *file, struct linux_dirent64 __user *dirent,
 		 unsigned int count, loff_t *pos);
+
+ /*
+  * fs/xattr.c:
+  */
+struct xattr_ctx {
+	/* Value of attribute */
+	const void __user *value;
+	size_t size;
+	/* Attribute name */
+	char *kname;
+	int kname_sz;
+	unsigned int flags;
+};
+
+
+int setxattr_copy(const char __user *name, struct xattr_ctx *ctx,
+		void **xattr_val);
+int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+		struct xattr_ctx *ctx, void *xattr_val);
diff --git a/fs/xattr.c b/fs/xattr.c
index 5c8c5175b385..fbe6c2b7ec47 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -25,6 +25,8 @@
 
 #include <linux/uaccess.h>
 
+#include "internal.h"
+
 static const char *
 strcmp_prefix(const char *a, const char *a_prefix)
 {
@@ -539,43 +541,84 @@ EXPORT_SYMBOL_GPL(vfs_removexattr);
 /*
  * Extended attribute SET operations
  */
-static long
-setxattr(struct user_namespace *mnt_userns, struct dentry *d,
-	 const char __user *name, const void __user *value, size_t size,
-	 int flags)
+
+int setxattr_copy(const char __user *name, struct xattr_ctx *ctx,
+		void **xattr_val)
 {
-	int error;
 	void *kvalue = NULL;
-	char kname[XATTR_NAME_MAX + 1];
+	int error;
 
-	if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
+	if (ctx->flags & ~(XATTR_CREATE|XATTR_REPLACE))
 		return -EINVAL;
 
-	error = strncpy_from_user(kname, name, sizeof(kname));
-	if (error == 0 || error == sizeof(kname))
-		error = -ERANGE;
+	error = strncpy_from_user(ctx->kname, name, ctx->kname_sz);
+	if (error == 0 || error == ctx->kname_sz)
+		return  -ERANGE;
 	if (error < 0)
 		return error;
 
-	if (size) {
-		if (size > XATTR_SIZE_MAX)
+	if (ctx->size) {
+		if (ctx->size > XATTR_SIZE_MAX)
 			return -E2BIG;
-		kvalue = kvmalloc(size, GFP_KERNEL);
+
+		kvalue = kvmalloc(ctx->size, GFP_KERNEL);
 		if (!kvalue)
 			return -ENOMEM;
-		if (copy_from_user(kvalue, value, size)) {
-			error = -EFAULT;
-			goto out;
+
+		if (copy_from_user(kvalue, ctx->value, ctx->size)) {
+			kvfree(kvalue);
+			return -EFAULT;
 		}
-		if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
-		    (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
-			posix_acl_fix_xattr_from_user(mnt_userns, kvalue, size);
 	}
 
-	error = vfs_setxattr(mnt_userns, d, kname, kvalue, size, flags);
-out:
-	kvfree(kvalue);
+	*xattr_val = kvalue;
+	return 0;
+}
+
+static void setxattr_convert(struct user_namespace *mnt_userns,
+			struct xattr_ctx *ctx, void *xattr_value)
+{
+	if (ctx->size &&
+		((strcmp(ctx->kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
+		(strcmp(ctx->kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0)))
+		posix_acl_fix_xattr_from_user(mnt_userns, xattr_value, ctx->size);
+}
+
+int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+		struct xattr_ctx *ctx, void *xattr_value)
+{
+	int error;
+
+	setxattr_convert(mnt_userns, ctx, xattr_value);
+	error = vfs_setxattr(mnt_userns, dentry, ctx->kname,
+			xattr_value, ctx->size, ctx->flags);
+
+	return error;
+}
+
+static long
+setxattr(struct user_namespace *mnt_userns, struct dentry *d,
+	const char __user *name, const void __user *value, size_t size,
+	int flags)
+{
+	char kname[XATTR_NAME_MAX + 1];
+	struct xattr_ctx ctx = {
+		.value    = value,
+		.size     = size,
+		.kname    = kname,
+		.kname_sz = sizeof(kname),
+		.flags    = flags,
+	};
+	void *xattr_value = NULL;
+	int error;
+
+	error = setxattr_copy(name, &ctx, &xattr_value);
+	if (error)
+		return error;
+
+	error = do_setxattr(mnt_userns, d, &ctx, xattr_value);
 
+	kvfree(xattr_value);
 	return error;
 }
 
-- 
2.30.2

[PATCH v7 3/5] fs: split off do_getxattr from getxattr

[Stefan Roesch]

This splits off do_getxattr function from the getxattr
function. This will allow io_uring to call it from its
io worker.

Signed-off-by: Stefan Roesch <shr@fb.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
---
 fs/internal.h |  6 ++++++
 fs/xattr.c    | 32 ++++++++++++++++++++------------
 2 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/fs/internal.h b/fs/internal.h
index 28b9f947f26e..d33e7a63a9c0 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -217,6 +217,12 @@ struct xattr_ctx {
 };
 
 
+ssize_t do_getxattr(struct user_namespace *mnt_userns,
+		    struct dentry *d,
+		    const char *kname,
+		    void __user *value,
+		    size_t size);
+
 int setxattr_copy(const char __user *name, struct xattr_ctx *ctx,
 		void **xattr_val);
 int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
diff --git a/fs/xattr.c b/fs/xattr.c
index fbe6c2b7ec47..cd36eeebf0c0 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -684,19 +684,12 @@ SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
 /*
  * Extended attribute GET operations
  */
-static ssize_t
-getxattr(struct user_namespace *mnt_userns, struct dentry *d,
-	 const char __user *name, void __user *value, size_t size)
+ssize_t
+do_getxattr(struct user_namespace *mnt_userns, struct dentry *d,
+	const char *kname, void __user *value, size_t size)
 {
-	ssize_t error;
 	void *kvalue = NULL;
-	char kname[XATTR_NAME_MAX + 1];
-
-	error = strncpy_from_user(kname, name, sizeof(kname));
-	if (error == 0 || error == sizeof(kname))
-		error = -ERANGE;
-	if (error < 0)
-		return error;
+	ssize_t error;
 
 	if (size) {
 		if (size > XATTR_SIZE_MAX)
@@ -720,10 +713,25 @@ getxattr(struct user_namespace *mnt_userns, struct dentry *d,
 	}
 
 	kvfree(kvalue);
-
 	return error;
 }
 
+static ssize_t
+getxattr(struct user_namespace *mnt_userns, struct dentry *d,
+	 const char __user *name, void __user *value, size_t size)
+{
+	ssize_t error;
+	char kname[XATTR_NAME_MAX + 1];
+
+	error = strncpy_from_user(kname, name, sizeof(kname));
+	if (error == 0 || error == sizeof(kname))
+		error = -ERANGE;
+	if (error < 0)
+		return error;
+
+	return do_getxattr(mnt_userns, d, kname, value, size);
+}
+
 static ssize_t path_getxattr(const char __user *pathname,
 			     const char __user *name, void __user *value,
 			     size_t size, unsigned int lookup_flags)
-- 
2.30.2

[PATCH v7 4/5] io_uring: add fsetxattr and setxattr support

[Stefan Roesch]

This adds support to io_uring for the fsetxattr and setxattr API.

Signed-off-by: Stefan Roesch <shr@fb.com>
---
 fs/io_uring.c                 | 167 ++++++++++++++++++++++++++++++++++
 include/uapi/linux/io_uring.h |   6 +-
 2 files changed, 172 insertions(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index c8258c784116..d26afce61321 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -82,6 +82,7 @@
 #include <linux/audit.h>
 #include <linux/security.h>
 #include <linux/atomic-ref.h>
+#include <linux/xattr.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/io_uring.h>
@@ -726,6 +727,13 @@ struct io_async_rw {
 	struct wait_page_queue		wpq;
 };
 
+struct io_xattr {
+	struct file			*file;
+	struct xattr_ctx		ctx;
+	void				*value;
+	struct filename			*filename;
+};
+
 enum {
 	REQ_F_FIXED_FILE_BIT	= IOSQE_FIXED_FILE_BIT,
 	REQ_F_IO_DRAIN_BIT	= IOSQE_IO_DRAIN_BIT,
@@ -866,6 +874,7 @@ struct io_kiocb {
 		struct io_symlink	symlink;
 		struct io_hardlink	hardlink;
 		struct io_getdents	getdents;
+		struct io_xattr		xattr;
 	};
 
 	u8				opcode;
@@ -1118,6 +1127,10 @@ static const struct io_op_def io_op_defs[] = {
 	[IORING_OP_GETDENTS] = {
 		.needs_file		= 1,
 	},
+	[IORING_OP_FSETXATTR] = {
+		.needs_file = 1
+	},
+	[IORING_OP_SETXATTR] = {},
 };
 
 /* requests with any of those set should undergo io_disarm_next() */
@@ -3887,6 +3900,141 @@ static int io_renameat(struct io_kiocb *req, unsigned int issue_flags)
 	return 0;
 }
 
+static int __io_setxattr_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;
+	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);
+
+	ix->ctx.kname = kmalloc(XATTR_NAME_MAX + 1, GFP_KERNEL);
+	if (!ix->ctx.kname)
+		return -ENOMEM;
+	ix->ctx.kname_sz = XATTR_NAME_MAX + 1;
+
+	ret = setxattr_copy(name, &ix->ctx, &ix->value);
+	if (ret) {
+		kfree(ix->ctx.kname);
+		return ret;
+	}
+
+	req->flags |= REQ_F_NEED_CLEANUP;
+	return 0;
+}
+
+static int io_setxattr_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_setxattr_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_fsetxattr_prep(struct io_kiocb *req,
+			const struct io_uring_sqe *sqe)
+{
+	return __io_setxattr_prep(req, sqe);
+}
+
+static int __io_setxattr(struct io_kiocb *req, unsigned int issue_flags,
+			struct path *path)
+{
+	struct io_xattr *ix = &req->xattr;
+	int ret;
+
+	ret = mnt_want_write(path->mnt);
+	if (!ret) {
+		ret = do_setxattr(mnt_user_ns(path->mnt), path->dentry,
+				&ix->ctx, ix->value);
+		mnt_drop_write(path->mnt);
+	}
+
+	return ret;
+}
+
+static int io_fsetxattr(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 = __io_setxattr(req, issue_flags, &req->file->f_path);
+
+	req->flags &= ~REQ_F_NEED_CLEANUP;
+	kfree(ix->ctx.kname);
+
+	if (ix->value)
+		kvfree(ix->value);
+	if (ret < 0)
+		req_set_fail(req);
+
+	io_req_complete(req, ret);
+	return 0;
+}
+
+static int io_setxattr(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);
+	if (!ret) {
+		ret = __io_setxattr(req, issue_flags, &path);
+		path_put(&path);
+		if (retry_estale(ret, lookup_flags)) {
+			lookup_flags |= LOOKUP_REVAL;
+			goto retry;
+		}
+	}
+	putname(ix->filename);
+
+	req->flags &= ~REQ_F_NEED_CLEANUP;
+	kfree(ix->ctx.kname);
+
+	if (ix->value)
+		kvfree(ix->value);
+	if (ret < 0)
+		req_set_fail(req);
+
+	io_req_complete(req, ret);
+	return 0;
+}
+
 static int io_unlinkat_prep(struct io_kiocb *req,
 			    const struct io_uring_sqe *sqe)
 {
@@ -6623,6 +6771,10 @@ static int io_req_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		return io_linkat_prep(req, sqe);
 	case IORING_OP_GETDENTS:
 		return io_getdents_prep(req, sqe);
+	case IORING_OP_FSETXATTR:
+		return io_fsetxattr_prep(req, sqe);
+	case IORING_OP_SETXATTR:
+		return io_setxattr_prep(req, sqe);
 	}
 
 	printk_once(KERN_WARNING "io_uring: unhandled opcode %d\n",
@@ -6764,6 +6916,14 @@ static void io_clean_op(struct io_kiocb *req)
 			putname(req->hardlink.oldpath);
 			putname(req->hardlink.newpath);
 			break;
+		case IORING_OP_SETXATTR:
+			if (req->xattr.filename)
+				putname(req->xattr.filename);
+			fallthrough;
+		case IORING_OP_FSETXATTR:
+			kfree(req->xattr.ctx.kname);
+			kvfree(req->xattr.value);
+			break;
 		}
 	}
 	if ((req->flags & REQ_F_POLLED) && req->apoll) {
@@ -6909,6 +7069,12 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
 	case IORING_OP_GETDENTS:
 		ret = io_getdents(req, issue_flags);
 		break;
+	case IORING_OP_FSETXATTR:
+		ret = io_fsetxattr(req, issue_flags);
+		break;
+	case IORING_OP_SETXATTR:
+		ret = io_setxattr(req, issue_flags);
+		break;
 	default:
 		ret = -EINVAL;
 		break;
@@ -11277,6 +11443,7 @@ static int __init io_uring_init(void)
 	BUILD_BUG_SQE_ELEM(42, __u16,  personality);
 	BUILD_BUG_SQE_ELEM(44, __s32,  splice_fd_in);
 	BUILD_BUG_SQE_ELEM(44, __u32,  file_index);
+	BUILD_BUG_SQE_ELEM(48, __u64,  addr3);
 
 	BUILD_BUG_ON(sizeof(struct io_uring_files_update) !=
 		     sizeof(struct io_uring_rsrc_update));
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 57dc88db5793..c62a8bec8cd4 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -45,6 +45,7 @@ struct io_uring_sqe {
 		__u32		rename_flags;
 		__u32		unlink_flags;
 		__u32		hardlink_flags;
+		__u32		xattr_flags;
 	};
 	__u64	user_data;	/* data to be passed back at completion time */
 	/* pack this to avoid bogus arm OABI complaints */
@@ -60,7 +61,8 @@ struct io_uring_sqe {
 		__s32	splice_fd_in;
 		__u32	file_index;
 	};
-	__u64	__pad2[2];
+	__u64	addr3;
+	__u64	__pad2[1];
 };
 
 enum {
@@ -144,6 +146,8 @@ enum {
 	IORING_OP_SYMLINKAT,
 	IORING_OP_LINKAT,
 	IORING_OP_GETDENTS,
+	IORING_OP_FSETXATTR,
+	IORING_OP_SETXATTR,
 
 	/* this goes last, obviously */
 	IORING_OP_LAST,
-- 
2.30.2

[PATCH v7 5/5] io_uring: add fgetxattr and getxattr support

[Stefan Roesch]

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

Signed-off-by: Stefan Roesch <shr@fb.com>
---
 fs/io_uring.c                 | 148 ++++++++++++++++++++++++++++++++++
 include/uapi/linux/io_uring.h |   2 +
 2 files changed, 150 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index d26afce61321..cd7b5b0742fd 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1131,6 +1131,10 @@ static const struct io_op_def io_op_defs[] = {
 		.needs_file = 1
 	},
 	[IORING_OP_SETXATTR] = {},
+	[IORING_OP_FGETXATTR] = {
+		.needs_file = 1
+	},
+	[IORING_OP_GETXATTR] = {},
 };
 
 /* requests with any of those set should undergo io_disarm_next() */
@@ -3900,6 +3904,133 @@ 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)
+{
+	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);
+	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;
+		}
+	}
+	putname(ix->filename);
+
+	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)
 {
@@ -6775,6 +6906,10 @@ static int io_req_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		return io_fsetxattr_prep(req, sqe);
 	case IORING_OP_SETXATTR:
 		return io_setxattr_prep(req, sqe);
+	case IORING_OP_FGETXATTR:
+		return io_fgetxattr_prep(req, sqe);
+	case IORING_OP_GETXATTR:
+		return io_getxattr_prep(req, sqe);
 	}
 
 	printk_once(KERN_WARNING "io_uring: unhandled opcode %d\n",
@@ -6924,6 +7059,13 @@ static void io_clean_op(struct io_kiocb *req)
 			kfree(req->xattr.ctx.kname);
 			kvfree(req->xattr.value);
 			break;
+		case IORING_OP_GETXATTR:
+			if (req->xattr.filename)
+				putname(req->xattr.filename);
+			fallthrough;
+		case IORING_OP_FGETXATTR:
+			kfree(req->xattr.ctx.kname);
+			break;
 		}
 	}
 	if ((req->flags & REQ_F_POLLED) && req->apoll) {
@@ -7075,6 +7217,12 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
 	case IORING_OP_SETXATTR:
 		ret = io_setxattr(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;
 	default:
 		ret = -EINVAL;
 		break;
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index c62a8bec8cd4..efc7ac9b3a6b 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -148,6 +148,8 @@ enum {
 	IORING_OP_GETDENTS,
 	IORING_OP_FSETXATTR,
 	IORING_OP_SETXATTR,
+	IORING_OP_FGETXATTR,
+	IORING_OP_GETXATTR,
 
 	/* this goes last, obviously */
 	IORING_OP_LAST,
-- 
2.30.2

Re: [PATCH v7 2/5] fs: split off setxattr_copy and do_setxattr function from setxattr

[Linus Torvalds]

On Thu, Dec 23, 2021 at 11:57 AM Stefan Roesch <shr@fb.com> wrote:
>
> +       /* Attribute name */
> +       char *kname;
> +       int kname_sz;

I still don't like this.

Clearly the "just embed the kname in the context" didn't work, but I
hate how this adds that "pointer and size", when the size really
should be part of the type.

The patch takes what used to be a fixed size, and turns it into
something we pass along as an argument - for no actual good reason.
The 'size' isn't even the size of the name, it's literally the size of
the allocation that has a fixed definition.

Can we perhaps do it another way, by just encoding the size in the
type itself - but keeping it as a pointer.

We have a fixed size for attribute names, so maybe we can do

        struct xattr_name {
                char name[XATTR_NAME_MAX + 1];
        };

and actually use that.

Because I don't see that kname_sz is ever validly anything else, and
ever has any actual value to be passed around?

Maybe some day we'd actually make that "xattr_name" structure also
have the actual length of the name in it, but that would still *not*
be the size of the allocation.

I think it's actively misleading to have "kname_sz' that isn't
actually the size of the name, but I also think it's stupid to have a
variable for what is a constant value.

             Linus

Re: [PATCH v7 2/5] fs: split off setxattr_copy and do_setxattr function from setxattr

[Stefan Roesch]

On 12/23/21 12:11 PM, Linus Torvalds wrote:
> On Thu, Dec 23, 2021 at 11:57 AM Stefan Roesch <shr@fb.com> wrote:
>>
>> +       /* Attribute name */
>> +       char *kname;
>> +       int kname_sz;
> 
> I still don't like this.
> 
> Clearly the "just embed the kname in the context" didn't work, but I
> hate how this adds that "pointer and size", when the size really
> should be part of the type.
> 
> The patch takes what used to be a fixed size, and turns it into
> something we pass along as an argument - for no actual good reason.
> The 'size' isn't even the size of the name, it's literally the size of
> the allocation that has a fixed definition.
> 
> Can we perhaps do it another way, by just encoding the size in the
> type itself - but keeping it as a pointer.
> 
> We have a fixed size for attribute names, so maybe we can do
> 
>         struct xattr_name {
>                 char name[XATTR_NAME_MAX + 1];
>         };
> 
> and actually use that.
> 
> Because I don't see that kname_sz is ever validly anything else, and
> ever has any actual value to be passed around?
> 
> Maybe some day we'd actually make that "xattr_name" structure also
> have the actual length of the name in it, but that would still *not*
> be the size of the allocation.
> 
> I think it's actively misleading to have "kname_sz' that isn't
> actually the size of the name, but I also think it's stupid to have a
> variable for what is a constant value.
> 
>              Linus
> 

Linus, I added the xattr_name struct and removed the kname_sz field from
the xattr_ctx struct. In addition the xattr_name struct is used in xattr.c
and io_uring.c.