Re: [PATCH 23/29] xfs: lift buffer allocation into xfs_ioc_attr_list

Darrick J. Wong
2020-01-21T18:49:20Z

On Tue, Jan 14, 2020 at 09:10:45AM +0100, Christoph Hellwig wrote:
> Lift the buffer allocation from the two callers into xfs_ioc_attr_list.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
> fs/xfs/xfs_ioctl.c | 39 ++++++++++++++++-----------------------
> fs/xfs/xfs_ioctl.h | 2 +-
> fs/xfs/xfs_ioctl32.c | 22 +++++-----------------
> 3 files changed, 22 insertions(+), 41 deletions(-)
>
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index a3a6c6882c6f..8d7b8ad21d9e 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -353,13 +353,14 @@ xfs_ioc_attr_put_listent(
> int
> xfs_ioc_attr_list(
> struct xfs_inode *dp,
> - char *buffer,
> + void __user *ubuf,
> int bufsize,
> int flags,
> struct attrlist_cursor_kern *cursor)
> {
> struct xfs_attr_list_context context;
> struct xfs_attrlist *alist;
> + void *buffer;
> int error;
>
> if (bufsize < sizeof(struct xfs_attrlist) ||
> @@ -381,11 +382,9 @@ xfs_ioc_attr_list(
> (cursor->hashval || cursor->blkno || cursor->offset))
> return -EINVAL;
>
> - /*
> - * Check for a properly aligned buffer.
> - */
> - if (((long)buffer) & (sizeof(int)-1))
> - return -EFAULT;
> + buffer = kmem_zalloc_large(bufsize, 0);
> + if (!buffer)
> + return -ENOMEM;
>
> /*
> * Initialize the output buffer.
> @@ -406,7 +405,13 @@ xfs_ioc_attr_list(
> alist->al_offset[0] = context.bufsize;
>
> error = xfs_attr_list(&context);
> - ASSERT(error <= 0);
> + if (error)
> + goto out_free;
> +
> + if (copy_to_user(ubuf, buffer, bufsize))
> + error = -EFAULT;
> +out_free:
> + kmem_free(buffer);
> return error;
> }
>
> @@ -420,7 +425,6 @@ xfs_attrlist_by_handle(
> struct xfs_fsop_attrlist_handlereq __user *p = arg;
> xfs_fsop_attrlist_handlereq_t al_hreq;
> struct dentry *dentry;
> - char *kbuf;
>
> if (!capable(CAP_SYS_ADMIN))
> return -EPERM;
> @@ -431,26 +435,15 @@ xfs_attrlist_by_handle(
> if (IS_ERR(dentry))
> return PTR_ERR(dentry);
>
> - kbuf = kmem_zalloc_large(al_hreq.buflen, 0);
> - if (!kbuf)
> - goto out_dput;
> -
> cursor = (attrlist_cursor_kern_t *)&al_hreq.pos;
> - error = xfs_ioc_attr_list(XFS_I(d_inode(dentry)), kbuf, al_hreq.buflen,
> - al_hreq.flags, cursor);
> + error = xfs_ioc_attr_list(XFS_I(d_inode(dentry)), al_hreq.buffer,
> + al_hreq.buflen, al_hreq.flags, cursor);
> if (error)
> - goto out_kfree;
> -
> - if (copy_to_user(&p->pos, cursor, sizeof(attrlist_cursor_kern_t))) {
> - error = -EFAULT;
> - goto out_kfree;
> - }
> + goto out_dput;
>
> - if (copy_to_user(al_hreq.buffer, kbuf, al_hreq.buflen))
> + if (copy_to_user(&p->pos, cursor, sizeof(attrlist_cursor_kern_t)))
> error = -EFAULT;
>
> -out_kfree:
> - kmem_free(kbuf);
> out_dput:
> dput(dentry);
> return error;
> diff --git a/fs/xfs/xfs_ioctl.h b/fs/xfs/xfs_ioctl.h
> index cb7b94c576a7..ec6448b259fb 100644
> --- a/fs/xfs/xfs_ioctl.h
> +++ b/fs/xfs/xfs_ioctl.h
> @@ -39,7 +39,7 @@ xfs_readlink_by_handle(
> 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);
> -int xfs_ioc_attr_list(struct xfs_inode *dp, char *buffer, int bufsize,
> +int xfs_ioc_attr_list(struct xfs_inode *dp, void __user *ubuf, int bufsize,
> int flags, struct attrlist_cursor_kern *cursor);
>
> extern struct dentry *
> diff --git a/fs/xfs/xfs_ioctl32.c b/fs/xfs/xfs_ioctl32.c
> index 840d17951407..17e14916757b 100644
> --- a/fs/xfs/xfs_ioctl32.c
> +++ b/fs/xfs/xfs_ioctl32.c
> @@ -359,7 +359,6 @@ xfs_compat_attrlist_by_handle(
> compat_xfs_fsop_attrlist_handlereq_t __user *p = arg;
> compat_xfs_fsop_attrlist_handlereq_t al_hreq;
> struct dentry *dentry;
> - char *kbuf;
>
> if (!capable(CAP_SYS_ADMIN))
> return -EPERM;
> @@ -371,27 +370,16 @@ xfs_compat_attrlist_by_handle(
> if (IS_ERR(dentry))
> return PTR_ERR(dentry);
>
> - error = -ENOMEM;
> - kbuf = kmem_zalloc_large(al_hreq.buflen, 0);
> - if (!kbuf)
> - goto out_dput;
> -
> cursor = (attrlist_cursor_kern_t *)&al_hreq.pos;
> - error = xfs_ioc_attr_list(XFS_I(d_inode(dentry)), kbuf, al_hreq.buflen,
> - al_hreq.flags, cursor);
> + error = xfs_ioc_attr_list(XFS_I(d_inode(dentry)),
> + compat_ptr(al_hreq.buffer), al_hreq.buflen,
> + al_hreq.flags, cursor);
> if (error)
> - goto out_kfree;
> -
> - if (copy_to_user(&p->pos, cursor, sizeof(attrlist_cursor_kern_t))) {
> - error = -EFAULT;
> - goto out_kfree;
> - }
> + goto out_dput;
>
> - if (copy_to_user(compat_ptr(al_hreq.buffer), kbuf, al_hreq.buflen))
> + if (copy_to_user(&p->pos, cursor, sizeof(attrlist_cursor_kern_t)))
> error = -EFAULT;
>
> -out_kfree:
> - kmem_free(kbuf);
> out_dput:
> dput(dentry);
> return error;
> --
> 2.24.1
>