Re: [PATCH 05/29] xfs: factor out a helper for a single XFS_IOC_ATTRMULTI_BY_HANDLE op

Darrick J. Wong
2020-01-21T17:55:02Z

On Tue, Jan 14, 2020 at 09:10:27AM +0100, Christoph Hellwig wrote:
> Add a new helper to handle a single attr multi ioctl operation that
> can be shared between the native and compat ioctl implementation.
>
> There is a slight change in heavior in that we don't break out of the
> loop when copying in the attribute name fails. The previous behavior
> was rather inconsistent here as it continued for any other kind of
> error.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/xfs/xfs_ioctl.c | 97 +++++++++++++++++++++++---------------------
> fs/xfs/xfs_ioctl.h | 18 ++------
> fs/xfs/xfs_ioctl32.c | 50 +++--------------------
> 3 files changed, 59 insertions(+), 106 deletions(-)
>
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index f4d5c865e29e..3dbbc1099375 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -347,7 +347,7 @@ xfs_attrlist_by_handle(
> return error;
> }
>
> -int
> +static int
> xfs_attrmulti_attr_get(
> struct inode *inode,
> unsigned char *name,
> @@ -379,7 +379,7 @@ xfs_attrmulti_attr_get(
> return error;
> }
>
> -int
> +static int
> xfs_attrmulti_attr_set(
> struct inode *inode,
> unsigned char *name,
> @@ -410,6 +410,51 @@ xfs_attrmulti_attr_set(
> return error;
> }
>
> +int
> +xfs_ioc_attrmulti_one(
> + struct file *parfilp,
> + struct inode *inode,
> + uint32_t opcode,
> + void __user *uname,
> + void __user *value,
> + uint32_t *len,
> + uint32_t flags)

That's a lot of arguments. Any chance you could change the ioctl32
handler to convert the compat_xfs_attr_multiop to a xfs_attr_multiop and
pass that into this function?

(I'm not passionate one way or another, I just don't like 7 argument
functions when most of them come from the same struct.)

--D

> +{
> + unsigned char *name;
> + int error;
> +
> + if ((flags & ATTR_ROOT) && (flags & ATTR_SECURE))
> + return -EINVAL;
> + flags &= ~ATTR_KERNEL_FLAGS;
> +
> + name = strndup_user(uname, MAXNAMELEN);
> + if (IS_ERR(name))
> + return PTR_ERR(name);
> +
> + switch (opcode) {
> + case ATTR_OP_GET:
> + error = xfs_attrmulti_attr_get(inode, name, value, len, flags);
> + break;
> + case ATTR_OP_REMOVE:
> + value = NULL;
> + *len = 0;
> + /*FALLTHRU*/
> + case ATTR_OP_SET:
> + error = mnt_want_write_file(parfilp);
> + if (error)
> + break;
> + error = xfs_attrmulti_attr_set(inode, name, value, *len, flags);
> + mnt_drop_write_file(parfilp);
> + break;
> + default:
> + error = -EINVAL;
> + break;
> + }
> +
> + kfree(name);
> + return error;
> +}
> +
> STATIC int
> xfs_attrmulti_by_handle(
> struct file *parfilp,
> @@ -420,7 +465,6 @@ xfs_attrmulti_by_handle(
> xfs_fsop_attrmulti_handlereq_t am_hreq;
> struct dentry *dentry;
> unsigned int i, size;
> - unsigned char *attr_name;
>
> if (!capable(CAP_SYS_ADMIN))
> return -EPERM;
> @@ -448,49 +492,10 @@ xfs_attrmulti_by_handle(
>
> error = 0;
> for (i = 0; i < am_hreq.opcount; i++) {
> - if ((ops[i].am_flags & ATTR_ROOT) &&
> - (ops[i].am_flags & ATTR_SECURE)) {
> - ops[i].am_error = -EINVAL;
> - continue;
> - }
> - ops[i].am_flags &= ~ATTR_KERNEL_FLAGS;
> -
> - attr_name = strndup_user(ops[i].am_attrname, MAXNAMELEN);
> - if (IS_ERR(attr_name)) {
> - ops[i].am_error = PTR_ERR(attr_name);
> - break;
> - }
> -
> - switch (ops[i].am_opcode) {
> - case ATTR_OP_GET:
> - ops[i].am_error = xfs_attrmulti_attr_get(
> - d_inode(dentry), attr_name,
> - ops[i].am_attrvalue, &ops[i].am_length,
> - ops[i].am_flags);
> - break;
> - case ATTR_OP_SET:
> - ops[i].am_error = mnt_want_write_file(parfilp);
> - if (ops[i].am_error)
> - break;
> - ops[i].am_error = xfs_attrmulti_attr_set(
> - d_inode(dentry), attr_name,
> - ops[i].am_attrvalue, ops[i].am_length,
> - ops[i].am_flags);
> - mnt_drop_write_file(parfilp);
> - break;
> - case ATTR_OP_REMOVE:
> - ops[i].am_error = mnt_want_write_file(parfilp);
> - if (ops[i].am_error)
> - break;
> - ops[i].am_error = xfs_attrmulti_attr_set(
> - d_inode(dentry), attr_name, NULL, 0,
> - ops[i].am_flags);
> - mnt_drop_write_file(parfilp);
> - break;
> - default:
> - ops[i].am_error = -EINVAL;
> - }
> - kfree(attr_name);
> + ops[i].am_error = xfs_ioc_attrmulti_one(parfilp,
> + d_inode(dentry), ops[i].am_opcode,
> + ops[i].am_attrname, ops[i].am_attrvalue,
> + &ops[i].am_length, ops[i].am_flags);
> }
>
> if (copy_to_user(am_hreq.ops, ops, size))
> diff --git a/fs/xfs/xfs_ioctl.h b/fs/xfs/xfs_ioctl.h
> index 819504df00ae..bb50cb3dc61f 100644
> --- a/fs/xfs/xfs_ioctl.h
> +++ b/fs/xfs/xfs_ioctl.h
> @@ -30,21 +30,9 @@ xfs_readlink_by_handle(
> struct file *parfilp,
> xfs_fsop_handlereq_t *hreq);
>
> -extern int
> -xfs_attrmulti_attr_get(
> - struct inode *inode,
> - unsigned char *name,
> - unsigned char __user *ubuf,
> - uint32_t *len,
> - uint32_t flags);
> -
> -extern int
> -xfs_attrmulti_attr_set(
> - struct inode *inode,
> - unsigned char *name,
> - const unsigned char __user *ubuf,
> - uint32_t len,
> - uint32_t flags);
> +int xfs_ioc_attrmulti_one(struct file *parfilp, struct inode *inode,
> + uint32_t opcode, void __user *uname, void __user *value,
> + uint32_t *len, uint32_t flags);
>
> extern struct dentry *
> xfs_handle_to_dentry(
> diff --git a/fs/xfs/xfs_ioctl32.c b/fs/xfs/xfs_ioctl32.c
> index e6a7f619a54c..ee428ddf51e5 100644
> --- a/fs/xfs/xfs_ioctl32.c
> +++ b/fs/xfs/xfs_ioctl32.c
> @@ -416,7 +416,6 @@ xfs_compat_attrmulti_by_handle(
> compat_xfs_fsop_attrmulti_handlereq_t am_hreq;
> struct dentry *dentry;
> unsigned int i, size;
> - unsigned char *attr_name;
>
> if (!capable(CAP_SYS_ADMIN))
> return -EPERM;
> @@ -445,50 +444,11 @@ xfs_compat_attrmulti_by_handle(
>
> error = 0;
> for (i = 0; i < am_hreq.opcount; i++) {
> - if ((ops[i].am_flags & ATTR_ROOT) &&
> - (ops[i].am_flags & ATTR_SECURE)) {
> - ops[i].am_error = -EINVAL;
> - continue;
> - }
> - ops[i].am_flags &= ~ATTR_KERNEL_FLAGS;
> -
> - attr_name = strndup_user(compat_ptr(ops[i].am_attrname),
> - MAXNAMELEN);
> - if (IS_ERR(attr_name)) {
> - ops[i].am_error = PTR_ERR(attr_name);
> - break;
> - }
> -
> - switch (ops[i].am_opcode) {
> - case ATTR_OP_GET:
> - ops[i].am_error = xfs_attrmulti_attr_get(
> - d_inode(dentry), attr_name,
> - compat_ptr(ops[i].am_attrvalue),
> - &ops[i].am_length, ops[i].am_flags);
> - break;
> - case ATTR_OP_SET:
> - ops[i].am_error = mnt_want_write_file(parfilp);
> - if (ops[i].am_error)
> - break;
> - ops[i].am_error = xfs_attrmulti_attr_set(
> - d_inode(dentry), attr_name,
> - compat_ptr(ops[i].am_attrvalue),
> - ops[i].am_length, ops[i].am_flags);
> - mnt_drop_write_file(parfilp);
> - break;
> - case ATTR_OP_REMOVE:
> - ops[i].am_error = mnt_want_write_file(parfilp);
> - if (ops[i].am_error)
> - break;
> - ops[i].am_error = xfs_attrmulti_attr_set(
> - d_inode(dentry), attr_name, NULL, 0,
> - ops[i].am_flags);
> - mnt_drop_write_file(parfilp);
> - break;
> - default:
> - ops[i].am_error = -EINVAL;
> - }
> - kfree(attr_name);
> + ops[i].am_error = xfs_ioc_attrmulti_one(parfilp,
> + d_inode(dentry), ops[i].am_opcode,
> + compat_ptr(ops[i].am_attrname),
> + compat_ptr(ops[i].am_attrvalue),
> + &ops[i].am_length, ops[i].am_flags);
> }
>
> if (copy_to_user(compat_ptr(am_hreq.ops), ops, size))
> --
> 2.24.1
>