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

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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@xxxxxx>

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

--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
> 



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