Commit 1a91794c authored by Stefan Roesch's avatar Stefan Roesch Committed by Jens Axboe
Browse files

fs: split off setxattr_copy and do_setxattr function from setxattr 



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: default avatarStefan Roesch <shr@fb.com>
Acked-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20220323154420.3301504-2-shr@fb.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 155bc950

fs/internal.h

+24 −0
Original line number Diff line number Diff line
@@ -191,3 +191,27 @@ long splice_file_to_pipe(struct file *in, 
			 struct pipe_inode_info *opipe,

			 loff_t *offset,

			 size_t len, unsigned int flags);



/*

 * fs/xattr.c:

 */

struct xattr_name {

	char name[XATTR_NAME_MAX + 1];

};



struct xattr_ctx {

	/* Value of attribute */

	union {

		const void __user *cvalue;

		void __user *value;

	};

	void *kvalue;

	size_t size;

	/* Attribute name */

	struct xattr_name *kname;

	unsigned int flags;

};



int setxattr_copy(const char __user *name, struct xattr_ctx *ctx);

int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,

		struct xattr_ctx *ctx);

fs/xattr.c

+59 −25
Original line number Diff line number Diff line
@@ -25,6 +25,8 @@ 


#include <linux/uaccess.h>



#include "internal.h"



static const char *

strcmp_prefix(const char *a, const char *a_prefix)

{
@@ -539,44 +541,76 @@ 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)

{

	int error;

	void *kvalue = NULL;

	char kname[XATTR_NAME_MAX + 1];



	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, name,

				sizeof(ctx->kname->name));

	if (error == 0 || error == sizeof(ctx->kname->name))

		return  -ERANGE;

	if (error < 0)

		return error;



	if (size) {

		if (size > XATTR_SIZE_MAX)

	error = 0;

	if (ctx->size) {

		if (ctx->size > XATTR_SIZE_MAX)

			return -E2BIG;

		kvalue = kvmalloc(size, GFP_KERNEL);

		if (!kvalue)

			return -ENOMEM;

		if (copy_from_user(kvalue, value, size)) {

			error = -EFAULT;

			goto out;



		ctx->kvalue = vmemdup_user(ctx->cvalue, ctx->size);

		if (IS_ERR(ctx->kvalue)) {

			error = PTR_ERR(ctx->kvalue);

			ctx->kvalue = NULL;

		}

		if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||

		    (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))

	}



	return error;

}



static void setxattr_convert(struct user_namespace *mnt_userns,

			     struct dentry *d, struct xattr_ctx *ctx)

{

	if (ctx->size &&

		((strcmp(ctx->kname->name, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||

		(strcmp(ctx->kname->name, XATTR_NAME_POSIX_ACL_DEFAULT) == 0)))

		posix_acl_fix_xattr_from_user(mnt_userns, d_inode(d),

						      kvalue, size);

						ctx->kvalue, ctx->size);

}



	error = vfs_setxattr(mnt_userns, d, kname, kvalue, size, flags);

out:

	kvfree(kvalue);

int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,

		struct xattr_ctx *ctx)

{

	setxattr_convert(mnt_userns, dentry, ctx);

	return vfs_setxattr(mnt_userns, dentry, ctx->kname->name,

			ctx->kvalue, ctx->size, ctx->flags);

}



static long

setxattr(struct user_namespace *mnt_userns, struct dentry *d,

	const char __user *name, const void __user *value, size_t size,

	int flags)

{

	struct xattr_name kname;

	struct xattr_ctx ctx = {

		.cvalue   = value,

		.kvalue   = NULL,

		.size     = size,

		.kname    = &kname,

		.flags    = flags,

	};

	int error;



	error = setxattr_copy(name, &ctx);

	if (error)

		return error;



	error = do_setxattr(mnt_userns, d, &ctx);



	kvfree(ctx.kvalue);

	return error;

}