xattr.c

linux 内核源代码

			discard_metapage(ea_buf->mp);
			dbFree(inode, blkno, (s64) blocks_needed);
			goto clean_up;
		}
		goto size_check;
	}
	ea_buf->flag = EA_EXTENT;
	ea_buf->mp = read_metapage(inode, addressDXD(&ji->ea),
				   lengthDXD(&ji->ea) << sb->s_blocksize_bits,
				   1);
	if (ea_buf->mp == NULL) {
		rc = -EIO;
		goto clean_up;
	}
	ea_buf->xattr = ea_buf->mp->data;
	ea_buf->max_size = (ea_size + sb->s_blocksize - 1) &
	    ~(sb->s_blocksize - 1);

      size_check:
	if (EALIST_SIZE(ea_buf->xattr) != ea_size) {
		printk(KERN_ERR "ea_get: invalid extended attribute\n");
		print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1,
				     ea_buf->xattr, ea_size, 1);
		ea_release(inode, ea_buf);
		rc = -EIO;
		goto clean_up;
	}

	return ea_size;

      clean_up:
	/* Rollback quota allocation */
	if (quota_allocation)
		DQUOT_FREE_BLOCK(inode, quota_allocation);

	return (rc);
}

static void ea_release(struct inode *inode, struct ea_buffer *ea_buf)
{
	if (ea_buf->flag & EA_MALLOC)
		kfree(ea_buf->xattr);
	else if (ea_buf->flag & EA_EXTENT) {
		assert(ea_buf->mp);
		release_metapage(ea_buf->mp);

		if (ea_buf->flag & EA_NEW)
			dbFree(inode, addressDXD(&ea_buf->new_ea),
			       lengthDXD(&ea_buf->new_ea));
	}
}

static int ea_put(tid_t tid, struct inode *inode, struct ea_buffer *ea_buf,
		  int new_size)
{
	struct jfs_inode_info *ji = JFS_IP(inode);
	unsigned long old_blocks, new_blocks;
	int rc = 0;

	if (new_size == 0) {
		ea_release(inode, ea_buf);
		ea_buf = NULL;
	} else if (ea_buf->flag & EA_INLINE) {
		assert(new_size <= sizeof (ji->i_inline_ea));
		ji->mode2 &= ~INLINEEA;
		ea_buf->new_ea.flag = DXD_INLINE;
		DXDsize(&ea_buf->new_ea, new_size);
		DXDaddress(&ea_buf->new_ea, 0);
		DXDlength(&ea_buf->new_ea, 0);
	} else if (ea_buf->flag & EA_MALLOC) {
		rc = ea_write(inode, ea_buf->xattr, new_size, &ea_buf->new_ea);
		kfree(ea_buf->xattr);
	} else if (ea_buf->flag & EA_NEW) {
		/* We have already allocated a new dxd */
		flush_metapage(ea_buf->mp);
	} else {
		/* ->xattr must point to original ea's metapage */
		rc = ea_write(inode, ea_buf->xattr, new_size, &ea_buf->new_ea);
		discard_metapage(ea_buf->mp);
	}
	if (rc)
		return rc;

	old_blocks = new_blocks = 0;

	if (ji->ea.flag & DXD_EXTENT) {
		invalidate_dxd_metapages(inode, ji->ea);
		old_blocks = lengthDXD(&ji->ea);
	}

	if (ea_buf) {
		txEA(tid, inode, &ji->ea, &ea_buf->new_ea);
		if (ea_buf->new_ea.flag & DXD_EXTENT) {
			new_blocks = lengthDXD(&ea_buf->new_ea);
			if (ji->ea.flag & DXD_INLINE)
				ji->mode2 |= INLINEEA;
		}
		ji->ea = ea_buf->new_ea;
	} else {
		txEA(tid, inode, &ji->ea, NULL);
		if (ji->ea.flag & DXD_INLINE)
			ji->mode2 |= INLINEEA;
		ji->ea.flag = 0;
		ji->ea.size = 0;
	}

	/* If old blocks exist, they must be removed from quota allocation. */
	if (old_blocks)
		DQUOT_FREE_BLOCK(inode, old_blocks);

	inode->i_ctime = CURRENT_TIME;

	return 0;
}

/*
 * can_set_system_xattr
 *
 * This code is specific to the system.* namespace.  It contains policy
 * which doesn't belong in the main xattr codepath.
 */
static int can_set_system_xattr(struct inode *inode, const char *name,
				const void *value, size_t value_len)
{
#ifdef CONFIG_JFS_POSIX_ACL
	struct posix_acl *acl;
	int rc;

	if (!is_owner_or_cap(inode))
		return -EPERM;

	/*
	 * POSIX_ACL_XATTR_ACCESS is tied to i_mode
	 */
	if (strcmp(name, POSIX_ACL_XATTR_ACCESS) == 0) {
		acl = posix_acl_from_xattr(value, value_len);
		if (IS_ERR(acl)) {
			rc = PTR_ERR(acl);
			printk(KERN_ERR "posix_acl_from_xattr returned %d\n",
			       rc);
			return rc;
		}
		if (acl) {
			mode_t mode = inode->i_mode;
			rc = posix_acl_equiv_mode(acl, &mode);
			posix_acl_release(acl);
			if (rc < 0) {
				printk(KERN_ERR
				       "posix_acl_equiv_mode returned %d\n",
				       rc);
				return rc;
			}
			inode->i_mode = mode;
			mark_inode_dirty(inode);
		}
		/*
		 * We're changing the ACL.  Get rid of the cached one
		 */
		acl =JFS_IP(inode)->i_acl;
		if (acl != JFS_ACL_NOT_CACHED)
			posix_acl_release(acl);
		JFS_IP(inode)->i_acl = JFS_ACL_NOT_CACHED;

		return 0;
	} else if (strcmp(name, POSIX_ACL_XATTR_DEFAULT) == 0) {
		acl = posix_acl_from_xattr(value, value_len);
		if (IS_ERR(acl)) {
			rc = PTR_ERR(acl);
			printk(KERN_ERR "posix_acl_from_xattr returned %d\n",
			       rc);
			return rc;
		}
		posix_acl_release(acl);

		/*
		 * We're changing the default ACL.  Get rid of the cached one
		 */
		acl =JFS_IP(inode)->i_default_acl;
		if (acl && (acl != JFS_ACL_NOT_CACHED))
			posix_acl_release(acl);
		JFS_IP(inode)->i_default_acl = JFS_ACL_NOT_CACHED;

		return 0;
	}
#endif			/* CONFIG_JFS_POSIX_ACL */
	return -EOPNOTSUPP;
}

/*
 * Most of the permission checking is done by xattr_permission in the vfs.
 * The local file system is responsible for handling the system.* namespace.
 * We also need to verify that this is a namespace that we recognize.
 */
static int can_set_xattr(struct inode *inode, const char *name,
			 const void *value, size_t value_len)
{
	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
		return can_set_system_xattr(inode, name, value, value_len);

	/*
	 * Don't allow setting an attribute in an unknown namespace.
	 */
	if (strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) &&
	    strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) &&
	    strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN) &&
	    strncmp(name, XATTR_OS2_PREFIX, XATTR_OS2_PREFIX_LEN))
		return -EOPNOTSUPP;

	return 0;
}

int __jfs_setxattr(tid_t tid, struct inode *inode, const char *name,
		   const void *value, size_t value_len, int flags)
{
	struct jfs_ea_list *ealist;
	struct jfs_ea *ea, *old_ea = NULL, *next_ea = NULL;
	struct ea_buffer ea_buf;
	int old_ea_size = 0;
	int xattr_size;
	int new_size;
	int namelen = strlen(name);
	char *os2name = NULL;
	int found = 0;
	int rc;
	int length;

	if (strncmp(name, XATTR_OS2_PREFIX, XATTR_OS2_PREFIX_LEN) == 0) {
		os2name = kmalloc(namelen - XATTR_OS2_PREFIX_LEN + 1,
				  GFP_KERNEL);
		if (!os2name)
			return -ENOMEM;
		strcpy(os2name, name + XATTR_OS2_PREFIX_LEN);
		name = os2name;
		namelen -= XATTR_OS2_PREFIX_LEN;
	}

	down_write(&JFS_IP(inode)->xattr_sem);

	xattr_size = ea_get(inode, &ea_buf, 0);
	if (xattr_size < 0) {
		rc = xattr_size;
		goto out;
	}

      again:
	ealist = (struct jfs_ea_list *) ea_buf.xattr;
	new_size = sizeof (struct jfs_ea_list);

	if (xattr_size) {
		for (ea = FIRST_EA(ealist); ea < END_EALIST(ealist);
		     ea = NEXT_EA(ea)) {
			if ((namelen == ea->namelen) &&
			    (memcmp(name, ea->name, namelen) == 0)) {
				found = 1;
				if (flags & XATTR_CREATE) {
					rc = -EEXIST;
					goto release;
				}
				old_ea = ea;
				old_ea_size = EA_SIZE(ea);
				next_ea = NEXT_EA(ea);
			} else
				new_size += EA_SIZE(ea);
		}
	}

	if (!found) {
		if (flags & XATTR_REPLACE) {
			rc = -ENODATA;
			goto release;
		}
		if (value == NULL) {
			rc = 0;
			goto release;
		}
	}
	if (value)
		new_size += sizeof (struct jfs_ea) + namelen + 1 + value_len;

	if (new_size > ea_buf.max_size) {
		/*
		 * We need to allocate more space for merged ea list.
		 * We should only have loop to again: once.
		 */
		ea_release(inode, &ea_buf);
		xattr_size = ea_get(inode, &ea_buf, new_size);
		if (xattr_size < 0) {
			rc = xattr_size;
			goto out;
		}
		goto again;
	}

	/* Remove old ea of the same name */
	if (found) {
		/* number of bytes following target EA */
		length = (char *) END_EALIST(ealist) - (char *) next_ea;
		if (length > 0)
			memmove(old_ea, next_ea, length);
		xattr_size -= old_ea_size;
	}

	/* Add new entry to the end */
	if (value) {
		if (xattr_size == 0)
			/* Completely new ea list */
			xattr_size = sizeof (struct jfs_ea_list);

		ea = (struct jfs_ea *) ((char *) ealist + xattr_size);
		ea->flag = 0;
		ea->namelen = namelen;
		ea->valuelen = (cpu_to_le16(value_len));
		memcpy(ea->name, name, namelen);
		ea->name[namelen] = 0;
		if (value_len)
			memcpy(&ea->name[namelen + 1], value, value_len);
		xattr_size += EA_SIZE(ea);
	}

	/* DEBUG - If we did this right, these number match */
	if (xattr_size != new_size) {
		printk(KERN_ERR
		       "jfs_xsetattr: xattr_size = %d, new_size = %d\n",
		       xattr_size, new_size);

		rc = -EINVAL;
		goto release;
	}

	/*
	 * If we're left with an empty list, there's no ea
	 */
	if (new_size == sizeof (struct jfs_ea_list))
		new_size = 0;

	ealist->size = cpu_to_le32(new_size);

	rc = ea_put(tid, inode, &ea_buf, new_size);

	goto out;
      release:
	ea_release(inode, &ea_buf);
      out:
	up_write(&JFS_IP(inode)->xattr_sem);

	kfree(os2name);

	return rc;
}

int jfs_setxattr(struct dentry *dentry, const char *name, const void *value,
		 size_t value_len, int flags)
{
	struct inode *inode = dentry->d_inode;
	struct jfs_inode_info *ji = JFS_IP(inode);
	int rc;
	tid_t tid;

	if ((rc = can_set_xattr(inode, name, value, value_len)))
		return rc;

	if (value == NULL) {	/* empty EA, do not remove */
		value = "";
		value_len = 0;
	}

	tid = txBegin(inode->i_sb, 0);
	mutex_lock(&ji->commit_mutex);
	rc = __jfs_setxattr(tid, dentry->d_inode, name, value, value_len,
			    flags);
	if (!rc)
		rc = txCommit(tid, 1, &inode, 0);
	txEnd(tid);
	mutex_unlock(&ji->commit_mutex);

	return rc;
}

ssize_t __jfs_getxattr(struct inode *inode, const char *name, void *data,
		       size_t buf_size)
{
	struct jfs_ea_list *ealist;
	struct jfs_ea *ea;
	struct ea_buffer ea_buf;
	int xattr_size;
	ssize_t size;
	int namelen = strlen(name);
	char *os2name = NULL;
	char *value;

	if (strncmp(name, XATTR_OS2_PREFIX, XATTR_OS2_PREFIX_LEN) == 0) {
		os2name = kmalloc(namelen - XATTR_OS2_PREFIX_LEN + 1,
				  GFP_KERNEL);
		if (!os2name)
			return -ENOMEM;
		strcpy(os2name, name + XATTR_OS2_PREFIX_LEN);
		name = os2name;
		namelen -= XATTR_OS2_PREFIX_LEN;
	}

	down_read(&JFS_IP(inode)->xattr_sem);

	xattr_size = ea_get(inode, &ea_buf, 0);

	if (xattr_size < 0) {
		size = xattr_size;
		goto out;
	}

	if (xattr_size == 0)
		goto not_found;

	ealist = (struct jfs_ea_list *) ea_buf.xattr;

	/* Find the named attribute */
	for (ea = FIRST_EA(ealist); ea < END_EALIST(ealist); ea = NEXT_EA(ea))
		if ((namelen == ea->namelen) &&
		    memcmp(name, ea->name, namelen) == 0) {
			/* Found it */
			size = le16_to_cpu(ea->valuelen);
			if (!data)
				goto release;
			else if (size > buf_size) {
				size = -ERANGE;
				goto release;
			}
			value = ((char *) &ea->name) + ea->namelen + 1;
			memcpy(data, value, size);
			goto release;
		}
      not_found:
	size = -ENODATA;
      release:
	ea_release(inode, &ea_buf);
      out:
	up_read(&JFS_IP(inode)->xattr_sem);

	kfree(os2name);

	return size;
}

ssize_t jfs_getxattr(struct dentry *dentry, const char *name, void *data,
		     size_t buf_size)
{
	int err;

	err = __jfs_getxattr(dentry->d_inode, name, data, buf_size);

	return err;
}

/*
 * No special permissions are needed to list attributes except for trusted.*
 */
static inline int can_list(struct jfs_ea *ea)
{
	return (strncmp(ea->name, XATTR_TRUSTED_PREFIX,
			    XATTR_TRUSTED_PREFIX_LEN) ||
		capable(CAP_SYS_ADMIN));
}

ssize_t jfs_listxattr(struct dentry * dentry, char *data, size_t buf_size)
{
	struct inode *inode = dentry->d_inode;
	char *buffer;
	ssize_t size = 0;
	int xattr_size;
	struct jfs_ea_list *ealist;
	struct jfs_ea *ea;
	struct ea_buffer ea_buf;

	down_read(&JFS_IP(inode)->xattr_sem);

	xattr_size = ea_get(inode, &ea_buf, 0);
	if (xattr_size < 0) {
		size = xattr_size;
		goto out;
	}

	if (xattr_size == 0)
		goto release;

	ealist = (struct jfs_ea_list *) ea_buf.xattr;

	/* compute required size of list */
	for (ea = FIRST_EA(ealist); ea < END_EALIST(ealist); ea = NEXT_EA(ea)) {
		if (can_list(ea))
			size += name_size(ea) + 1;
	}

	if (!data)
		goto release;

	if (size > buf_size) {
		size = -ERANGE;
		goto release;
	}

	/* Copy attribute names to buffer */
	buffer = data;
	for (ea = FIRST_EA(ealist); ea < END_EALIST(ealist); ea = NEXT_EA(ea)) {
		if (can_list(ea)) {
			int namelen = copy_name(buffer, ea);
			buffer += namelen + 1;
		}
	}

      release:
	ea_release(inode, &ea_buf);
      out:
	up_read(&JFS_IP(inode)->xattr_sem);
	return size;
}

int jfs_removexattr(struct dentry *dentry, const char *name)
{
	struct inode *inode = dentry->d_inode;
	struct jfs_inode_info *ji = JFS_IP(inode);
	int rc;
	tid_t tid;

	if ((rc = can_set_xattr(inode, name, NULL, 0)))
		return rc;

	tid = txBegin(inode->i_sb, 0);
	mutex_lock(&ji->commit_mutex);
	rc = __jfs_setxattr(tid, dentry->d_inode, name, NULL, 0, XATTR_REPLACE);
	if (!rc)
		rc = txCommit(tid, 1, &inode, 0);
	txEnd(tid);
	mutex_unlock(&ji->commit_mutex);

	return rc;
}

#ifdef CONFIG_JFS_SECURITY
int jfs_init_security(tid_t tid, struct inode *inode, struct inode *dir)
{
	int rc;
	size_t len;
	void *value;
	char *suffix;
	char *name;

	rc = security_inode_init_security(inode, dir, &suffix, &value, &len);
	if (rc) {
		if (rc == -EOPNOTSUPP)
			return 0;
		return rc;
	}
	name = kmalloc(XATTR_SECURITY_PREFIX_LEN + 1 + strlen(suffix),
		       GFP_NOFS);
	if (!name) {
		rc = -ENOMEM;
		goto kmalloc_failed;
	}
	strcpy(name, XATTR_SECURITY_PREFIX);
	strcpy(name + XATTR_SECURITY_PREFIX_LEN, suffix);

	rc = __jfs_setxattr(tid, inode, name, value, len, 0);

	kfree(name);
kmalloc_failed:
	kfree(suffix);
	kfree(value);

	return rc;
}
#endif