On Wed, Dec 22, 2021 at 01:01:26PM -0800, Stefan Roesch wrote:
> This adds support to io_uring for the fsetxattr and setxattr API.
>
> Signed-off-by: Stefan Roesch <shr@xxxxxx>
> ---
> fs/io_uring.c | 170 ++++++++++++++++++++++++++++++++++
> include/uapi/linux/io_uring.h | 6 +-
> 2 files changed, 175 insertions(+), 1 deletion(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index c8258c784116..8b6c70d6cacc 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 +3900,144 @@ 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 user_namespace *user_ns)
> +{
> + struct io_xattr *ix = &req->xattr;
> + const char __user *name;
> + void *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_setup(user_ns, name, &ix->ctx);
Looking at this a bit closer, the setxattr_setup() function converts the
vfs caps prior to vfs_setxattr(). That shouldn't be done there though.
The conversion should be done when mnt_want_write() is held in
__io_setxattr() exactly how we do for setxattr()-based calls in
fs/xattr.c. This will guard against changes of relevant mount properties
(current or future). It will also allow you to simplify your
setxattr_setup() function a bit and you don't need to retrieve the
mount's idmapping until __io_setxattr().
Right now you're splitting updating the xattrs over the prep and commit
stage and I worry that in fully async contexts this is easy to miss. So
I'd rather do it in one place. Since we can't move it all into
vfs_setxattr() similar to what we did for fscaps because it's used in a
bunch of contexts where the conversion isn't wanted we should simply
expose do_setxattr() similar to do_getxattr() you're adding.
So on top of your current patchset I'd suggest you do something like the
following (completely untested):
>From 6bcd3efc3293bb91599ee73272262ac596ab4608 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner@xxxxxxxxxx>
Date: Thu, 23 Dec 2021 15:23:14 +0100
Subject: [PATCH] UNTESTED
---
fs/internal.h | 8 +++++---
fs/io_uring.c | 21 +++++++++-----------
fs/xattr.c | 55 ++++++++++++++++++++++++++++++++++-----------------
3 files changed, 51 insertions(+), 33 deletions(-)
diff --git a/fs/internal.h b/fs/internal.h
index ea0433799dbc..08259fa98b2e 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -222,6 +222,8 @@ ssize_t do_getxattr(struct user_namespace *mnt_userns,
void __user *value,
size_t size);
-void *setxattr_setup(struct user_namespace *mnt_userns,
- const char __user *name,
- struct xattr_ctx *ctx);
+int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+ struct xattr_ctx *ctx, void *xattr_val);
+
+int setxattr_copy(const char __user *name, struct xattr_ctx *ctx,
+ void **xattr_val);
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 5dd01f19d915..c910c29e1632 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4040,12 +4040,11 @@ static int io_getxattr(struct io_kiocb *req, unsigned int issue_flags)
}
static int __io_setxattr_prep(struct io_kiocb *req,
- const struct io_uring_sqe *sqe,
- struct user_namespace *user_ns)
+ const struct io_uring_sqe *sqe)
{
struct io_xattr *ix = &req->xattr;
const char __user *name;
- void *ret;
+ int ret;
if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
@@ -4065,13 +4064,12 @@ static int __io_setxattr_prep(struct io_kiocb *req,
return -ENOMEM;
ix->ctx.kname_sz = XATTR_NAME_MAX + 1;
- ret = setxattr_setup(user_ns, name, &ix->ctx);
- if (IS_ERR(ret)) {
+ ret = setxattr_copy(name, &ix->ctx, &ix->value);
+ if (ret) {
kfree(ix->ctx.kname);
- return PTR_ERR(ret);
+ return ret;
}
- ix->value = ret;
req->flags |= REQ_F_NEED_CLEANUP;
return 0;
}
@@ -4083,7 +4081,7 @@ static int io_setxattr_prep(struct io_kiocb *req,
const char __user *path;
int ret;
- ret = __io_setxattr_prep(req, sqe, current_user_ns());
+ ret = __io_setxattr_prep(req, sqe);
if (ret)
return ret;
@@ -4101,7 +4099,7 @@ static int io_setxattr_prep(struct io_kiocb *req,
static int io_fsetxattr_prep(struct io_kiocb *req,
const struct io_uring_sqe *sqe)
{
- return __io_setxattr_prep(req, sqe, file_mnt_user_ns(req->file));
+ return __io_setxattr_prep(req, sqe);
}
static int __io_setxattr(struct io_kiocb *req, unsigned int issue_flags,
@@ -4112,9 +4110,8 @@ static int __io_setxattr(struct io_kiocb *req, unsigned int issue_flags,
ret = mnt_want_write(path->mnt);
if (!ret) {
- ret = vfs_setxattr(mnt_user_ns(path->mnt), path->dentry,
- ix->ctx.kname, ix->value, ix->ctx.size,
- ix->ctx.flags);
+ ret = do_setxattr(mnt_user_ns(path->mnt), path->dentry,
+ &ix->ctx, ix->value);
mnt_drop_write(path->mnt);
}
diff --git a/fs/xattr.c b/fs/xattr.c
index a675c7f0ea0c..03a44c5895d1 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -542,40 +542,59 @@ EXPORT_SYMBOL_GPL(vfs_removexattr);
* Extended attribute SET operations
*/
-void *setxattr_setup(struct user_namespace *mnt_userns, const char __user *name,
- struct xattr_ctx *ctx)
+int setxattr_copy(const char __user *name, struct xattr_ctx *ctx,
+ void **xattr_val)
{
void *kvalue = NULL;
int error;
if (ctx->flags & ~(XATTR_CREATE|XATTR_REPLACE))
- return ERR_PTR(-EINVAL);
+ return -EINVAL;
error = strncpy_from_user(ctx->kname, name, ctx->kname_sz);
if (error == 0 || error == ctx->kname_sz)
- return ERR_PTR(-ERANGE);
+ return -ERANGE;
if (error < 0)
- return ERR_PTR(error);
+ return error;
if (ctx->size) {
if (ctx->size > XATTR_SIZE_MAX)
- return ERR_PTR(-E2BIG);
+ return -E2BIG;
kvalue = kvmalloc(ctx->size, GFP_KERNEL);
if (!kvalue)
- return ERR_PTR(-ENOMEM);
+ return -ENOMEM;
if (copy_from_user(kvalue, ctx->value, ctx->size)) {
kvfree(kvalue);
- return ERR_PTR(-EFAULT);
+ return -EFAULT;
}
-
- if ((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, kvalue, ctx->size);
}
- return kvalue;
+ *xattr_val = kvalue;
+ return 0;
+}
+
+static void setxattr_convert(struct user_namespace *mnt_userns,
+ struct xattr_ctx *ctx, void *kvalue)
+{
+ 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, kvalue, ctx->size);
+}
+
+int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+ struct xattr_ctx *ctx, void *xattr_val)
+{
+ void *kvalue = NULL;
+ int error;
+
+ setxattr_convert(mnt_userns, ctx, kvalue);
+ error = vfs_setxattr(mnt_userns, dentry, ctx->kname,
+ kvalue, ctx->size, ctx->flags);
+ kvfree(kvalue);
+ return error;
}
static long
@@ -591,14 +610,14 @@ setxattr(struct user_namespace *mnt_userns, struct dentry *d,
.kname_sz = sizeof(kname),
.flags = flags,
};
- void *kvalue;
+ void *kvalue = NULL;
int error;
- kvalue = setxattr_setup(mnt_userns, name, &ctx);
- if (IS_ERR(kvalue))
- return PTR_ERR(kvalue);
+ error = setxattr_copy(name, &ctx, &kvalue);
+ if (error)
+ return error;
- error = vfs_setxattr(mnt_userns, d, kname, kvalue, size, flags);
+ error = do_setxattr(mnt_userns, d, &ctx, kvalue);
kvfree(kvalue);
return error;
--
2.30.2
