*
* This file is released under the GPLv2.
*/
+
+#include <linux/pagemap.h>
+#include <linux/backing-dev.h>
+#include <linux/capability.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/xattr.h>
+#include <linux/security.h>
+
+#include "kernfs-internal.h"
+
+static const struct address_space_operations sysfs_aops = {
+ .readpage = simple_readpage,
+ .write_begin = simple_write_begin,
+ .write_end = simple_write_end,
+};
+
+static struct backing_dev_info sysfs_backing_dev_info = {
+ .name = "sysfs",
+ .ra_pages = 0, /* No readahead */
+ .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
+};
+
+static const struct inode_operations sysfs_inode_operations = {
+ .permission = sysfs_permission,
+ .setattr = sysfs_setattr,
+ .getattr = sysfs_getattr,
+ .setxattr = sysfs_setxattr,
+};
+
+int __init sysfs_inode_init(void)
+{
+ return bdi_init(&sysfs_backing_dev_info);
+}
+
+static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
+{
+ struct sysfs_inode_attrs *attrs;
+ struct iattr *iattrs;
+
+ attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
+ if (!attrs)
+ return NULL;
+ iattrs = &attrs->ia_iattr;
+
+ /* assign default attributes */
+ iattrs->ia_mode = sd->s_mode;
+ iattrs->ia_uid = GLOBAL_ROOT_UID;
+ iattrs->ia_gid = GLOBAL_ROOT_GID;
+ iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
+
+ return attrs;
+}
+
+static int __kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
+{
+ struct sysfs_inode_attrs *sd_attrs;
+ struct iattr *iattrs;
+ unsigned int ia_valid = iattr->ia_valid;
+
+ sd_attrs = sd->s_iattr;
+
+ if (!sd_attrs) {
+ /* setting attributes for the first time, allocate now */
+ sd_attrs = sysfs_init_inode_attrs(sd);
+ if (!sd_attrs)
+ return -ENOMEM;
+ sd->s_iattr = sd_attrs;
+ }
+ /* attributes were changed at least once in past */
+ iattrs = &sd_attrs->ia_iattr;
+
+ if (ia_valid & ATTR_UID)
+ iattrs->ia_uid = iattr->ia_uid;
+ if (ia_valid & ATTR_GID)
+ iattrs->ia_gid = iattr->ia_gid;
+ if (ia_valid & ATTR_ATIME)
+ iattrs->ia_atime = iattr->ia_atime;
+ if (ia_valid & ATTR_MTIME)
+ iattrs->ia_mtime = iattr->ia_mtime;
+ if (ia_valid & ATTR_CTIME)
+ iattrs->ia_ctime = iattr->ia_ctime;
+ if (ia_valid & ATTR_MODE) {
+ umode_t mode = iattr->ia_mode;
+ iattrs->ia_mode = sd->s_mode = mode;
+ }
+ return 0;
+}
+
+/**
+ * kernfs_setattr - set iattr on a node
+ * @sd: target node
+ * @iattr: iattr to set
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
+{
+ int ret;
+
+ mutex_lock(&sysfs_mutex);
+ ret = __kernfs_setattr(sd, iattr);
+ mutex_unlock(&sysfs_mutex);
+ return ret;
+}
+
+int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
+{
+ struct inode *inode = dentry->d_inode;
+ struct sysfs_dirent *sd = dentry->d_fsdata;
+ int error;
+
+ if (!sd)
+ return -EINVAL;
+
+ mutex_lock(&sysfs_mutex);
+ error = inode_change_ok(inode, iattr);
+ if (error)
+ goto out;
+
+ error = __kernfs_setattr(sd, iattr);
+ if (error)
+ goto out;
+
+ /* this ignores size changes */
+ setattr_copy(inode, iattr);
+
+out:
+ mutex_unlock(&sysfs_mutex);
+ return error;
+}
+
+static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata,
+ u32 *secdata_len)
+{
+ struct sysfs_inode_attrs *iattrs;
+ void *old_secdata;
+ size_t old_secdata_len;
+
+ if (!sd->s_iattr) {
+ sd->s_iattr = sysfs_init_inode_attrs(sd);
+ if (!sd->s_iattr)
+ return -ENOMEM;
+ }
+
+ iattrs = sd->s_iattr;
+ old_secdata = iattrs->ia_secdata;
+ old_secdata_len = iattrs->ia_secdata_len;
+
+ iattrs->ia_secdata = *secdata;
+ iattrs->ia_secdata_len = *secdata_len;
+
+ *secdata = old_secdata;
+ *secdata_len = old_secdata_len;
+ return 0;
+}
+
+int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
+ size_t size, int flags)
+{
+ struct sysfs_dirent *sd = dentry->d_fsdata;
+ void *secdata;
+ int error;
+ u32 secdata_len = 0;
+
+ if (!sd)
+ return -EINVAL;
+
+ if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
+ const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
+ error = security_inode_setsecurity(dentry->d_inode, suffix,
+ value, size, flags);
+ if (error)
+ goto out;
+ error = security_inode_getsecctx(dentry->d_inode,
+ &secdata, &secdata_len);
+ if (error)
+ goto out;
+
+ mutex_lock(&sysfs_mutex);
+ error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
+ mutex_unlock(&sysfs_mutex);
+
+ if (secdata)
+ security_release_secctx(secdata, secdata_len);
+ } else
+ return -EINVAL;
+out:
+ return error;
+}
+
+static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
+{
+ inode->i_mode = mode;
+ inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+}
+
+static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
+{
+ inode->i_uid = iattr->ia_uid;
+ inode->i_gid = iattr->ia_gid;
+ inode->i_atime = iattr->ia_atime;
+ inode->i_mtime = iattr->ia_mtime;
+ inode->i_ctime = iattr->ia_ctime;
+}
+
+static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
+{
+ struct sysfs_inode_attrs *iattrs = sd->s_iattr;
+
+ inode->i_mode = sd->s_mode;
+ if (iattrs) {
+ /* sysfs_dirent has non-default attributes
+ * get them from persistent copy in sysfs_dirent
+ */
+ set_inode_attr(inode, &iattrs->ia_iattr);
+ security_inode_notifysecctx(inode,
+ iattrs->ia_secdata,
+ iattrs->ia_secdata_len);
+ }
+
+ if (sysfs_type(sd) == SYSFS_DIR)
+ set_nlink(inode, sd->s_dir.subdirs + 2);
+}
+
+int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
+ struct kstat *stat)
+{
+ struct sysfs_dirent *sd = dentry->d_fsdata;
+ struct inode *inode = dentry->d_inode;
+
+ mutex_lock(&sysfs_mutex);
+ sysfs_refresh_inode(sd, inode);
+ mutex_unlock(&sysfs_mutex);
+
+ generic_fillattr(inode, stat);
+ return 0;
+}
+
+static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
+{
+ kernfs_get(sd);
+ inode->i_private = sd;
+ inode->i_mapping->a_ops = &sysfs_aops;
+ inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
+ inode->i_op = &sysfs_inode_operations;
+
+ set_default_inode_attr(inode, sd->s_mode);
+ sysfs_refresh_inode(sd, inode);
+
+ /* initialize inode according to type */
+ switch (sysfs_type(sd)) {
+ case SYSFS_DIR:
+ inode->i_op = &sysfs_dir_inode_operations;
+ inode->i_fop = &sysfs_dir_operations;
+ break;
+ case SYSFS_KOBJ_ATTR:
+ inode->i_size = sd->s_attr.size;
+ inode->i_fop = &kernfs_file_operations;
+ break;
+ case SYSFS_KOBJ_LINK:
+ inode->i_op = &sysfs_symlink_inode_operations;
+ break;
+ default:
+ BUG();
+ }
+
+ unlock_new_inode(inode);
+}
+
+/**
+ * sysfs_get_inode - get inode for sysfs_dirent
+ * @sb: super block
+ * @sd: sysfs_dirent to allocate inode for
+ *
+ * Get inode for @sd. If such inode doesn't exist, a new inode
+ * is allocated and basics are initialized. New inode is
+ * returned locked.
+ *
+ * LOCKING:
+ * Kernel thread context (may sleep).
+ *
+ * RETURNS:
+ * Pointer to allocated inode on success, NULL on failure.
+ */
+struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
+{
+ struct inode *inode;
+
+ inode = iget_locked(sb, sd->s_ino);
+ if (inode && (inode->i_state & I_NEW))
+ sysfs_init_inode(sd, inode);
+
+ return inode;
+}
+
+/*
+ * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
+ * To prevent the sysfs inode numbers from being freed prematurely we take a
+ * reference to sysfs_dirent from the sysfs inode. A
+ * super_operations.evict_inode() implementation is needed to drop that
+ * reference upon inode destruction.
+ */
+void sysfs_evict_inode(struct inode *inode)
+{
+ struct sysfs_dirent *sd = inode->i_private;
+
+ truncate_inode_pages(&inode->i_data, 0);
+ clear_inode(inode);
+ kernfs_put(sd);
+}
+
+int sysfs_permission(struct inode *inode, int mask)
+{
+ struct sysfs_dirent *sd;
+
+ if (mask & MAY_NOT_BLOCK)
+ return -ECHILD;
+
+ sd = inode->i_private;
+
+ mutex_lock(&sysfs_mutex);
+ sysfs_refresh_inode(sd, inode);
+ mutex_unlock(&sysfs_mutex);
+
+ return generic_permission(inode, mask);
+}
projects / ~andy / linux / blobdiff