super.c

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#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/key.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/file.h>
#include <linux/crypto.h>
#include <linux/statfs.h>
#include <linux/magic.h>
#include "ecryptfs_kernel.h"

struct kmem_cache *ecryptfs_inode_info_cache;

static struct inode *ecryptfs_alloc_inode(struct super_block *sb)
{
    struct ecryptfs_inode_info *inode_info;
    struct inode *inode = NULL;

    inode_info = kmem_cache_alloc(ecryptfs_inode_info_cache, GFP_KERNEL);
    if (unlikely(!inode_info))
        goto out;
    ecryptfs_init_crypt_stat(&inode_info->crypt_stat);
    mutex_init(&inode_info->lower_file_mutex);
    atomic_set(&inode_info->lower_file_count, 0);
    inode_info->lower_file = NULL;
    inode = &inode_info->vfs_inode;
out:
    return inode;
}

static void ecryptfs_i_callback(struct rcu_head *head)
{
    struct inode *inode = container_of(head, struct inode, i_rcu);
    struct ecryptfs_inode_info *inode_info;
    inode_info = ecryptfs_inode_to_private(inode);

    kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
}

static void ecryptfs_destroy_inode(struct inode *inode)
{
    struct ecryptfs_inode_info *inode_info;

    inode_info = ecryptfs_inode_to_private(inode);
    BUG_ON(inode_info->lower_file);
    ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat);
    call_rcu(&inode->i_rcu, ecryptfs_i_callback);
}

static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
    struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
    int rc;

    if (!lower_dentry->d_sb->s_op->statfs)
        return -ENOSYS;

    rc = lower_dentry->d_sb->s_op->statfs(lower_dentry, buf);
    if (rc)
        return rc;

    buf->f_type = ECRYPTFS_SUPER_MAGIC;
    rc = ecryptfs_set_f_namelen(&buf->f_namelen, buf->f_namelen,
           &ecryptfs_superblock_to_private(dentry->d_sb)->mount_crypt_stat);

    return rc;
}

static void ecryptfs_evict_inode(struct inode *inode)
{
    truncate_inode_pages(&inode->i_data, 0);
    clear_inode(inode);
    iput(ecryptfs_inode_to_lower(inode));
}

static int ecryptfs_show_options(struct seq_file *m, struct dentry *root)
{
    struct super_block *sb = root->d_sb;
    struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
        &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
    struct ecryptfs_global_auth_tok *walker;

    mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
    list_for_each_entry(walker,
                &mount_crypt_stat->global_auth_tok_list,
                mount_crypt_stat_list) {
        if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK)
            seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig);
        else
            seq_printf(m, ",ecryptfs_sig=%s", walker->sig);
    }
    mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);

    seq_printf(m, ",ecryptfs_cipher=%s",
        mount_crypt_stat->global_default_cipher_name);

    if (mount_crypt_stat->global_default_cipher_key_size)
        seq_printf(m, ",ecryptfs_key_bytes=%zd",
               mount_crypt_stat->global_default_cipher_key_size);
    if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)
        seq_printf(m, ",ecryptfs_passthrough");
    if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
        seq_printf(m, ",ecryptfs_xattr_metadata");
    if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
        seq_printf(m, ",ecryptfs_encrypted_view");
    if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS)
        seq_printf(m, ",ecryptfs_unlink_sigs");
    if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
        seq_printf(m, ",ecryptfs_mount_auth_tok_only");

    return 0;
}

const struct super_operations ecryptfs_sops = {
    .alloc_inode = ecryptfs_alloc_inode,
    .destroy_inode = ecryptfs_destroy_inode,
    .statfs = ecryptfs_statfs,
    .remount_fs = NULL,
    .evict_inode = ecryptfs_evict_inode,
    .show_options = ecryptfs_show_options
};