fs/cachefiles/xattr.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /* CacheFiles extended attribute management
  *
  * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  */

 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/fsnotify.h>
 #include <linux/quotaops.h>
 #include <linux/xattr.h>
 #include <linux/slab.h>
 #include "internal.h"

 #define CACHEFILES_COOKIE_TYPE_DATA 1

 struct cachefiles_xattr {
 	__be64	object_size;	/* Actual size of the object */
 	__be64	zero_point;	/* Size after which server has no data not written by us */
 	__u8	type;		/* Type of object */
 	__u8	content;	/* Content presence (enum cachefiles_content) */
 	__u8	data[];		/* netfs coherency data */
 } __packed;

 static const char cachefiles_xattr_cache[] =
 	XATTR_USER_PREFIX "CacheFiles.cache";

 struct cachefiles_vol_xattr {
 	__be32	reserved;	/* Reserved, should be 0 */
 	__u8	data[];		/* netfs volume coherency data */
 } __packed;

 /*
  * set the state xattr on a cache file
  */
 int cachefiles_set_object_xattr(struct cachefiles_object *object)
 {
 	struct cachefiles_xattr *buf;
 	struct dentry *dentry;
 	struct file *file = object->file;
 	unsigned int len = object->cookie->aux_len;
 	int ret;

 	if (!file)
 		return -ESTALE;
 	dentry = file->f_path.dentry;

 	_enter("%x,#%d", object->debug_id, len);

 	buf = kmalloc(sizeof(struct cachefiles_xattr) + len, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;

 	buf->object_size	= cpu_to_be64(object->cookie->object_size);
 	buf->zero_point		= 0;
 	buf->type		= CACHEFILES_COOKIE_TYPE_DATA;
 	buf->content		= object->content_info;
 	if (test_bit(FSCACHE_COOKIE_LOCAL_WRITE, &object->cookie->flags))
 		buf->content	= CACHEFILES_CONTENT_DIRTY;
 	if (len > 0)
 		memcpy(buf->data, fscache_get_aux(object->cookie), len);

 	ret = cachefiles_inject_write_error();
 	if (ret == 0) {
 		ret = mnt_want_write_file(file);
 		if (ret == 0) {
 			ret = vfs_setxattr(&nop_mnt_idmap, dentry,
 					   cachefiles_xattr_cache, buf,
 					   sizeof(struct cachefiles_xattr) + len, 0);
 			mnt_drop_write_file(file);
 		}
 	}
 	if (ret < 0) {
 		trace_cachefiles_vfs_error(object, file_inode(file), ret,
 					   cachefiles_trace_setxattr_error);
 		trace_cachefiles_coherency(object, file_inode(file)->i_ino,
 					   buf->content,
 					   cachefiles_coherency_set_fail);
 		if (ret != -ENOMEM)
 			cachefiles_io_error_obj(
 				object,
 				"Failed to set xattr with error %d", ret);
 	} else {
 		trace_cachefiles_coherency(object, file_inode(file)->i_ino,
 					   buf->content,
 					   cachefiles_coherency_set_ok);
 	}

 	kfree(buf);
 	_leave(" = %d", ret);
 	return ret;
 }

 /*
  * check the consistency between the backing cache and the FS-Cache cookie
  */
 int cachefiles_check_auxdata(struct cachefiles_object *object, struct file *file)
 {
 	struct cachefiles_xattr *buf;
 	struct dentry *dentry = file->f_path.dentry;
 	unsigned int len = object->cookie->aux_len, tlen;
 	const void *p = fscache_get_aux(object->cookie);
 	enum cachefiles_coherency_trace why;
 	ssize_t xlen;
 	int ret = -ESTALE;

 	tlen = sizeof(struct cachefiles_xattr) + len;
 	buf = kmalloc(tlen, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;

 	xlen = cachefiles_inject_read_error();
 	if (xlen == 0)
 		xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, tlen);
 	if (xlen != tlen) {
 		if (xlen < 0) {
 			ret = xlen;
 			trace_cachefiles_vfs_error(object, file_inode(file), xlen,
 						   cachefiles_trace_getxattr_error);
 		}
 		if (xlen == -EIO)
 			cachefiles_io_error_obj(
 				object,
 				"Failed to read aux with error %zd", xlen);
 		why = cachefiles_coherency_check_xattr;
 	} else if (buf->type != CACHEFILES_COOKIE_TYPE_DATA) {
 		why = cachefiles_coherency_check_type;
 	} else if (memcmp(buf->data, p, len) != 0) {
 		why = cachefiles_coherency_check_aux;
 	} else if (be64_to_cpu(buf->object_size) != object->cookie->object_size) {
 		why = cachefiles_coherency_check_objsize;
 	} else if (buf->content == CACHEFILES_CONTENT_DIRTY) {
 		// TODO: Begin conflict resolution
 		pr_warn("Dirty object in cache\n");
 		why = cachefiles_coherency_check_dirty;
 	} else {
 		why = cachefiles_coherency_check_ok;
 		ret = 0;
 	}

 	trace_cachefiles_coherency(object, file_inode(file)->i_ino,
 				   buf->content, why);
 	kfree(buf);
 	return ret;
 }

 /*
  * remove the object's xattr to mark it stale
  */
 int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
 				   struct cachefiles_object *object,
 				   struct dentry *dentry)
 {
 	int ret;

 	ret = cachefiles_inject_remove_error();
 	if (ret == 0) {
 		ret = mnt_want_write(cache->mnt);
 		if (ret == 0) {
 			ret = vfs_removexattr(&nop_mnt_idmap, dentry,
 					      cachefiles_xattr_cache);
 			mnt_drop_write(cache->mnt);
 		}
 	}
 	if (ret < 0) {
 		trace_cachefiles_vfs_error(object, d_inode(dentry), ret,
 					   cachefiles_trace_remxattr_error);
 		if (ret == -ENOENT || ret == -ENODATA)
 			ret = 0;
 		else if (ret != -ENOMEM)
 			cachefiles_io_error(cache,
 					    "Can't remove xattr from %lu"
 					    " (error %d)",
 					    d_backing_inode(dentry)->i_ino, -ret);
 	}

 	_leave(" = %d", ret);
 	return ret;
 }

 /*
  * Stick a marker on the cache object to indicate that it's dirty.
  */
 void cachefiles_prepare_to_write(struct fscache_cookie *cookie)
 {
 	const struct cred *saved_cred;
 	struct cachefiles_object *object = cookie->cache_priv;
 	struct cachefiles_cache *cache = object->volume->cache;

 	_enter("c=%08x", object->cookie->debug_id);

 	if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) {
 		cachefiles_begin_secure(cache, &saved_cred);
 		cachefiles_set_object_xattr(object);
 		cachefiles_end_secure(cache, saved_cred);
 	}
 }

 /*
  * Set the state xattr on a volume directory.
  */
 bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume)
 {
 	struct cachefiles_vol_xattr *buf;
 	unsigned int len = volume->vcookie->coherency_len;
 	const void *p = volume->vcookie->coherency;
 	struct dentry *dentry = volume->dentry;
 	int ret;

 	_enter("%x,#%d", volume->vcookie->debug_id, len);

 	len += sizeof(*buf);
 	buf = kmalloc(len, GFP_KERNEL);
 	if (!buf)
 		return false;
 	buf->reserved = cpu_to_be32(0);
 	memcpy(buf->data, p, volume->vcookie->coherency_len);

 	ret = cachefiles_inject_write_error();
 	if (ret == 0) {
 		ret = mnt_want_write(volume->cache->mnt);
 		if (ret == 0) {
 			ret = vfs_setxattr(&nop_mnt_idmap, dentry,
 					   cachefiles_xattr_cache,
 					   buf, len, 0);
 			mnt_drop_write(volume->cache->mnt);
 		}
 	}
 	if (ret < 0) {
 		trace_cachefiles_vfs_error(NULL, d_inode(dentry), ret,
 					   cachefiles_trace_setxattr_error);
 		trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino,
 					       cachefiles_coherency_vol_set_fail);
 		if (ret != -ENOMEM)
 			cachefiles_io_error(
 				volume->cache, "Failed to set xattr with error %d", ret);
 	} else {
 		trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino,
 					       cachefiles_coherency_vol_set_ok);
 	}

 	kfree(buf);
 	_leave(" = %d", ret);
 	return ret == 0;
 }

 /*
  * Check the consistency between the backing cache and the volume cookie.
  */
 int cachefiles_check_volume_xattr(struct cachefiles_volume *volume)
 {
 	struct cachefiles_vol_xattr *buf;
 	struct dentry *dentry = volume->dentry;
 	unsigned int len = volume->vcookie->coherency_len;
 	const void *p = volume->vcookie->coherency;
 	enum cachefiles_coherency_trace why;
 	ssize_t xlen;
 	int ret = -ESTALE;

 	_enter("");

 	len += sizeof(*buf);
 	buf = kmalloc(len, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;

 	xlen = cachefiles_inject_read_error();
 	if (xlen == 0)
 		xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, len);
 	if (xlen != len) {
 		if (xlen < 0) {
 			ret = xlen;
 			trace_cachefiles_vfs_error(NULL, d_inode(dentry), xlen,
 						   cachefiles_trace_getxattr_error);
 			if (xlen == -EIO)
 				cachefiles_io_error(
 					volume->cache,
 					"Failed to read xattr with error %zd", xlen);
 		}
 		why = cachefiles_coherency_vol_check_xattr;
 	} else if (buf->reserved != cpu_to_be32(0)) {
 		why = cachefiles_coherency_vol_check_resv;
 	} else if (memcmp(buf->data, p, len - sizeof(*buf)) != 0) {
 		why = cachefiles_coherency_vol_check_cmp;
 	} else {
 		why = cachefiles_coherency_vol_check_ok;
 		ret = 0;
 	}

 	trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino, why);
 	kfree(buf);
 	_leave(" = %d", ret);
 	return ret;
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/* CacheFiles extended attribute management
	*
	* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells (dhowells@redhat.com)
	*/

	#include <linux/module.h>
	#include <linux/sched.h>
	#include <linux/file.h>
	#include <linux/fs.h>
	#include <linux/fsnotify.h>
	#include <linux/quotaops.h>
	#include <linux/xattr.h>
	#include <linux/slab.h>
	#include "internal.h"

	#define CACHEFILES_COOKIE_TYPE_DATA 1

	struct cachefiles_xattr {
	__be64 object_size; /* Actual size of the object */
	__be64 zero_point; /* Size after which server has no data not written by us */
	__u8 type; /* Type of object */
	__u8 content; /* Content presence (enum cachefiles_content) */
	__u8 data[]; /* netfs coherency data */
	} __packed;

	static const char cachefiles_xattr_cache[] =
	XATTR_USER_PREFIX "CacheFiles.cache";

	struct cachefiles_vol_xattr {
	__be32 reserved; /* Reserved, should be 0 */
	__u8 data[]; /* netfs volume coherency data */
	} __packed;

	/*
	* set the state xattr on a cache file
	*/
	int cachefiles_set_object_xattr(struct cachefiles_object *object)
	{
	struct cachefiles_xattr *buf;
	struct dentry *dentry;
	struct file *file = object->file;
	unsigned int len = object->cookie->aux_len;
	int ret;

	if (!file)
	return -ESTALE;
	dentry = file->f_path.dentry;

	_enter("%x,#%d", object->debug_id, len);

	buf = kmalloc(sizeof(struct cachefiles_xattr) + len, GFP_KERNEL);
	if (!buf)
	return -ENOMEM;

	buf->object_size = cpu_to_be64(object->cookie->object_size);
	buf->zero_point = 0;
	buf->type = CACHEFILES_COOKIE_TYPE_DATA;
	buf->content = object->content_info;
	if (test_bit(FSCACHE_COOKIE_LOCAL_WRITE, &object->cookie->flags))
	buf->content = CACHEFILES_CONTENT_DIRTY;
	if (len > 0)
	memcpy(buf->data, fscache_get_aux(object->cookie), len);

	ret = cachefiles_inject_write_error();
	if (ret == 0) {
	ret = mnt_want_write_file(file);
	if (ret == 0) {
	ret = vfs_setxattr(&nop_mnt_idmap, dentry,
	cachefiles_xattr_cache, buf,
	sizeof(struct cachefiles_xattr) + len, 0);
	mnt_drop_write_file(file);
	}
	}
	if (ret < 0) {
	trace_cachefiles_vfs_error(object, file_inode(file), ret,
	cachefiles_trace_setxattr_error);
	trace_cachefiles_coherency(object, file_inode(file)->i_ino,
	buf->content,
	cachefiles_coherency_set_fail);
	if (ret != -ENOMEM)
	cachefiles_io_error_obj(
	object,
	"Failed to set xattr with error %d", ret);
	} else {
	trace_cachefiles_coherency(object, file_inode(file)->i_ino,
	buf->content,
	cachefiles_coherency_set_ok);
	}

	kfree(buf);
	_leave(" = %d", ret);
	return ret;
	}

	/*
	* check the consistency between the backing cache and the FS-Cache cookie
	*/
	int cachefiles_check_auxdata(struct cachefiles_object object, struct file file)
	{
	struct cachefiles_xattr *buf;
	struct dentry *dentry = file->f_path.dentry;
	unsigned int len = object->cookie->aux_len, tlen;
	const void *p = fscache_get_aux(object->cookie);
	enum cachefiles_coherency_trace why;
	ssize_t xlen;
	int ret = -ESTALE;

	tlen = sizeof(struct cachefiles_xattr) + len;
	buf = kmalloc(tlen, GFP_KERNEL);
	if (!buf)
	return -ENOMEM;

	xlen = cachefiles_inject_read_error();
	if (xlen == 0)
	xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, tlen);
	if (xlen != tlen) {
	if (xlen < 0) {
	ret = xlen;
	trace_cachefiles_vfs_error(object, file_inode(file), xlen,
	cachefiles_trace_getxattr_error);
	}
	if (xlen == -EIO)
	cachefiles_io_error_obj(
	object,
	"Failed to read aux with error %zd", xlen);
	why = cachefiles_coherency_check_xattr;
	} else if (buf->type != CACHEFILES_COOKIE_TYPE_DATA) {
	why = cachefiles_coherency_check_type;
	} else if (memcmp(buf->data, p, len) != 0) {
	why = cachefiles_coherency_check_aux;
	} else if (be64_to_cpu(buf->object_size) != object->cookie->object_size) {
	why = cachefiles_coherency_check_objsize;
	} else if (buf->content == CACHEFILES_CONTENT_DIRTY) {
	// TODO: Begin conflict resolution
	pr_warn("Dirty object in cache\n");
	why = cachefiles_coherency_check_dirty;
	} else {
	why = cachefiles_coherency_check_ok;
	ret = 0;
	}

	trace_cachefiles_coherency(object, file_inode(file)->i_ino,
	buf->content, why);
	kfree(buf);
	return ret;
	}

	/*
	* remove the object's xattr to mark it stale
	*/
	int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
	struct cachefiles_object *object,
	struct dentry *dentry)
	{
	int ret;

	ret = cachefiles_inject_remove_error();
	if (ret == 0) {
	ret = mnt_want_write(cache->mnt);
	if (ret == 0) {
	ret = vfs_removexattr(&nop_mnt_idmap, dentry,
	cachefiles_xattr_cache);
	mnt_drop_write(cache->mnt);
	}
	}
	if (ret < 0) {
	trace_cachefiles_vfs_error(object, d_inode(dentry), ret,
	cachefiles_trace_remxattr_error);
	if (ret == -ENOENT \|\| ret == -ENODATA)
	ret = 0;
	else if (ret != -ENOMEM)
	cachefiles_io_error(cache,
	"Can't remove xattr from %lu"
	" (error %d)",
	d_backing_inode(dentry)->i_ino, -ret);
	}

	_leave(" = %d", ret);
	return ret;
	}

	/*
	* Stick a marker on the cache object to indicate that it's dirty.
	*/
	void cachefiles_prepare_to_write(struct fscache_cookie *cookie)
	{
	const struct cred *saved_cred;
	struct cachefiles_object *object = cookie->cache_priv;
	struct cachefiles_cache *cache = object->volume->cache;

	_enter("c=%08x", object->cookie->debug_id);

	if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) {
	cachefiles_begin_secure(cache, &saved_cred);
	cachefiles_set_object_xattr(object);
	cachefiles_end_secure(cache, saved_cred);
	}
	}

	/*
	* Set the state xattr on a volume directory.
	*/
	bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume)
	{
	struct cachefiles_vol_xattr *buf;
	unsigned int len = volume->vcookie->coherency_len;
	const void *p = volume->vcookie->coherency;
	struct dentry *dentry = volume->dentry;
	int ret;

	_enter("%x,#%d", volume->vcookie->debug_id, len);

	len += sizeof(*buf);
	buf = kmalloc(len, GFP_KERNEL);
	if (!buf)
	return false;
	buf->reserved = cpu_to_be32(0);
	memcpy(buf->data, p, volume->vcookie->coherency_len);

	ret = cachefiles_inject_write_error();
	if (ret == 0) {
	ret = mnt_want_write(volume->cache->mnt);
	if (ret == 0) {
	ret = vfs_setxattr(&nop_mnt_idmap, dentry,
	cachefiles_xattr_cache,
	buf, len, 0);
	mnt_drop_write(volume->cache->mnt);
	}
	}
	if (ret < 0) {
	trace_cachefiles_vfs_error(NULL, d_inode(dentry), ret,
	cachefiles_trace_setxattr_error);
	trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino,
	cachefiles_coherency_vol_set_fail);
	if (ret != -ENOMEM)
	cachefiles_io_error(
	volume->cache, "Failed to set xattr with error %d", ret);
	} else {
	trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino,
	cachefiles_coherency_vol_set_ok);
	}

	kfree(buf);
	_leave(" = %d", ret);
	return ret == 0;
	}

	/*
	* Check the consistency between the backing cache and the volume cookie.
	*/
	int cachefiles_check_volume_xattr(struct cachefiles_volume *volume)
	{
	struct cachefiles_vol_xattr *buf;
	struct dentry *dentry = volume->dentry;
	unsigned int len = volume->vcookie->coherency_len;
	const void *p = volume->vcookie->coherency;
	enum cachefiles_coherency_trace why;
	ssize_t xlen;
	int ret = -ESTALE;

	_enter("");

	len += sizeof(*buf);
	buf = kmalloc(len, GFP_KERNEL);
	if (!buf)
	return -ENOMEM;

	xlen = cachefiles_inject_read_error();
	if (xlen == 0)
	xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, len);
	if (xlen != len) {
	if (xlen < 0) {
	ret = xlen;
	trace_cachefiles_vfs_error(NULL, d_inode(dentry), xlen,
	cachefiles_trace_getxattr_error);
	if (xlen == -EIO)
	cachefiles_io_error(
	volume->cache,
	"Failed to read xattr with error %zd", xlen);
	}
	why = cachefiles_coherency_vol_check_xattr;
	} else if (buf->reserved != cpu_to_be32(0)) {
	why = cachefiles_coherency_vol_check_resv;
	} else if (memcmp(buf->data, p, len - sizeof(*buf)) != 0) {
	why = cachefiles_coherency_vol_check_cmp;
	} else {
	why = cachefiles_coherency_vol_check_ok;
	ret = 0;
	}

	trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino, why);
	kfree(buf);
	_leave(" = %d", ret);
	return ret;
	}