Commit 2e1a5328 authored by Amir Goldstein's avatar Amir Goldstein Committed by Miklos Szeredi
Browse files

ovl: factor out ovl_check_origin_fh() 



Re-factor ovl_check_origin() and ovl_get_origin(), so origin fh xattr is
read from upper inode only once during lookup with multiple lower layers
and only once when verifying index entry origin.

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent d583ed7d

fs/overlayfs/namei.c

+92 −50
Original line number Diff line number Diff line
@@ -87,9 +87,36 @@ static int ovl_acceptable(void *ctx, struct dentry *dentry) 
	return 1;

}



/*

 * Check validity of an overlay file handle buffer.

 *

 * Return 0 for a valid file handle.

 * Return -ENODATA for "origin unknown".

 * Return <0 for an invalid file handle.

 */

static int ovl_check_fh_len(struct ovl_fh *fh, int fh_len)

{

	if (fh_len < sizeof(struct ovl_fh) || fh_len < fh->len)

		return -EINVAL;



	if (fh->magic != OVL_FH_MAGIC)

		return -EINVAL;



	/* Treat larger version and unknown flags as "origin unknown" */

	if (fh->version > OVL_FH_VERSION || fh->flags & ~OVL_FH_FLAG_ALL)

		return -ENODATA;



	/* Treat endianness mismatch as "origin unknown" */

	if (!(fh->flags & OVL_FH_FLAG_ANY_ENDIAN) &&

	    (fh->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN)

		return -ENODATA;



	return 0;

}



static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry)

{

	int res;

	int res, err;

	struct ovl_fh *fh = NULL;



	res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
@@ -110,20 +137,12 @@ static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry) 
	if (res < 0)

		goto fail;



	if (res < sizeof(struct ovl_fh) || res < fh->len)

		goto invalid;



	if (fh->magic != OVL_FH_MAGIC)

		goto invalid;



	/* Treat larger version and unknown flags as "origin unknown" */

	if (fh->version > OVL_FH_VERSION || fh->flags & ~OVL_FH_FLAG_ALL)

		goto out;



	/* Treat endianness mismatch as "origin unknown" */

	if (!(fh->flags & OVL_FH_FLAG_ANY_ENDIAN) &&

	    (fh->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN)

	err = ovl_check_fh_len(fh, res);

	if (err < 0) {

		if (err == -ENODATA)

			goto out;

		goto invalid;

	}



	return fh;
@@ -139,22 +158,17 @@ invalid: 
	goto out;

}



static struct dentry *ovl_get_origin(struct dentry *dentry,

				     struct vfsmount *mnt)

static struct dentry *ovl_decode_fh(struct ovl_fh *fh, struct vfsmount *mnt)

{

	struct dentry *origin = NULL;

	struct ovl_fh *fh = ovl_get_origin_fh(dentry);

	struct dentry *origin;

	int bytes;



	if (IS_ERR_OR_NULL(fh))

		return (struct dentry *)fh;



	/*

	 * Make sure that the stored uuid matches the uuid of the lower

	 * layer where file handle will be decoded.

	 */

	if (!uuid_equal(&fh->uuid, &mnt->mnt_sb->s_uuid))

		goto out;

		return NULL;



	bytes = (fh->len - offsetof(struct ovl_fh, fid));

	origin = exportfs_decode_fh(mnt, (struct fid *)fh->fid,
@@ -164,22 +178,15 @@ static struct dentry *ovl_get_origin(struct dentry *dentry, 
		/* Treat stale file handle as "origin unknown" */

		if (origin == ERR_PTR(-ESTALE))

			origin = NULL;

		goto out;

		return origin;

	}



	if (ovl_dentry_weird(origin) ||

	    ((d_inode(origin)->i_mode ^ d_inode(dentry)->i_mode) & S_IFMT))

		goto invalid;

	if (ovl_dentry_weird(origin)) {

		dput(origin);

		return NULL;

	}



out:

	kfree(fh);

	return origin;



invalid:

	pr_warn_ratelimited("overlayfs: invalid origin (%pd2)\n", origin);

	dput(origin);

	origin = NULL;

	goto out;

}



static bool ovl_is_opaquedir(struct dentry *dentry)
@@ -284,9 +291,9 @@ static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d, 
}





static int ovl_check_origin(struct dentry *upperdentry,

static int ovl_check_origin_fh(struct ovl_fh *fh, struct dentry *upperdentry,

			       struct ovl_path *lower, unsigned int numlower,

			    struct ovl_path **stackp, unsigned int *ctrp)

			       struct ovl_path **stackp)

{

	struct vfsmount *mnt;

	struct dentry *origin = NULL;
@@ -294,18 +301,20 @@ static int ovl_check_origin(struct dentry *upperdentry, 


	for (i = 0; i < numlower; i++) {

		mnt = lower[i].layer->mnt;

		origin = ovl_get_origin(upperdentry, mnt);

		if (IS_ERR(origin))

			return PTR_ERR(origin);



		origin = ovl_decode_fh(fh, mnt);

		if (origin)

			break;

	}



	if (!origin)

		return 0;

		return -ESTALE;

	else if (IS_ERR(origin))

		return PTR_ERR(origin);



	if (!ovl_is_whiteout(upperdentry) &&

	    ((d_inode(origin)->i_mode ^ d_inode(upperdentry)->i_mode) & S_IFMT))

		goto invalid;



	BUG_ON(*ctrp);

	if (!*stackp)

		*stackp = kmalloc(sizeof(struct ovl_path), GFP_KERNEL);

	if (!*stackp) {
@@ -313,9 +322,41 @@ static int ovl_check_origin(struct dentry *upperdentry, 
		return -ENOMEM;

	}

	**stackp = (struct ovl_path){.dentry = origin, .layer = lower[i].layer};

	*ctrp = 1;



	return 0;



invalid:

	pr_warn_ratelimited("overlayfs: invalid origin (%pd2, ftype=%x, origin ftype=%x).\n",

			    upperdentry, d_inode(upperdentry)->i_mode & S_IFMT,

			    d_inode(origin)->i_mode & S_IFMT);

	dput(origin);

	return -EIO;

}



static int ovl_check_origin(struct dentry *upperdentry,

			    struct ovl_path *lower, unsigned int numlower,

			    struct ovl_path **stackp, unsigned int *ctrp)

{

	struct ovl_fh *fh = ovl_get_origin_fh(upperdentry);

	int err;



	if (IS_ERR_OR_NULL(fh))

		return PTR_ERR(fh);



	err = ovl_check_origin_fh(fh, upperdentry, lower, numlower, stackp);

	kfree(fh);



	if (err) {

		if (err == -ESTALE)

			return 0;

		return err;

	}



	if (WARN_ON(*ctrp))

		return -EIO;



	*ctrp = 1;

	return 0;

}



/*
@@ -389,7 +430,6 @@ int ovl_verify_index(struct dentry *index, struct ovl_path *lower, 
	size_t len;

	struct ovl_path origin = { };

	struct ovl_path *stack = &origin;

	unsigned int ctr = 0;

	int err;



	if (!d_inode(index))
@@ -420,16 +460,18 @@ int ovl_verify_index(struct dentry *index, struct ovl_path *lower, 
		goto fail;



	err = -EINVAL;

	if (hex2bin((u8 *)fh, index->d_name.name, len) || len != fh->len)

	if (hex2bin((u8 *)fh, index->d_name.name, len))

		goto fail;



	err = ovl_check_fh_len(fh, len);

	if (err)

		goto fail;



	err = ovl_verify_origin_fh(index, fh);

	if (err)

		goto fail;



	err = ovl_check_origin(index, lower, numlower, &stack, &ctr);

	if (!err && !ctr)

		err = -ESTALE;

	err = ovl_check_origin_fh(fh, index, lower, numlower, &stack);

	if (err)

		goto fail;

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