fs/ext4/symlink.c

   1 /*
   2  *  linux/fs/ext4/symlink.c
   3  *
   4  * Only fast symlinks left here - the rest is done by generic code. AV, 1999
   5  *
   6  * Copyright (C) 1992, 1993, 1994, 1995
   7  * Remy Card (card@masi.ibp.fr)
   8  * Laboratoire MASI - Institut Blaise Pascal
   9  * Universite Pierre et Marie Curie (Paris VI)
  10  *
  11  *  from
  12  *
  13  *  linux/fs/minix/symlink.c
  14  *
  15  *  Copyright (C) 1991, 1992  Linus Torvalds
  16  *
  17  *  ext4 symlink handling code
  18  */
  19
  20 #include <linux/fs.h>
  21 #include <linux/namei.h>
  22 #include "ext4.h"
  23 #include "xattr.h"
  24
  25 static const char *ext4_encrypted_get_link(struct dentry *dentry,
  26                                            struct inode *inode,
  27                                            struct delayed_call *done)
  28 {
  29         struct page *cpage = NULL;
  30         char *caddr, *paddr = NULL;
  31         struct fscrypt_str cstr, pstr;
  32         struct fscrypt_symlink_data *sd;
  33         int res;
  34         u32 max_size = inode->i_sb->s_blocksize;
  35
  36         if (!dentry)
  37                 return ERR_PTR(-ECHILD);
  38
  39         res = fscrypt_get_encryption_info(inode);
  40         if (res)
  41                 return ERR_PTR(res);
  42
  43         if (ext4_inode_is_fast_symlink(inode)) {
  44                 caddr = (char *) EXT4_I(inode)->i_data;
  45                 max_size = sizeof(EXT4_I(inode)->i_data);
  46         } else {
  47                 cpage = read_mapping_page(inode->i_mapping, 0, NULL);
  48                 if (IS_ERR(cpage))
  49                         return ERR_CAST(cpage);
  50                 caddr = page_address(cpage);
  51         }
  52
  53         /* Symlink is encrypted */
  54         sd = (struct fscrypt_symlink_data *)caddr;
  55         cstr.name = sd->encrypted_path;
  56         cstr.len  = le16_to_cpu(sd->len);
  57         if ((cstr.len + sizeof(struct fscrypt_symlink_data) - 1) > max_size) {
  58                 /* Symlink data on the disk is corrupted */
  59                 res = -EFSCORRUPTED;
  60                 goto errout;
  61         }
  62
  63         res = fscrypt_fname_alloc_buffer(inode, cstr.len, &pstr);
  64         if (res)
  65                 goto errout;
  66         paddr = pstr.name;
  67
  68         res = fscrypt_fname_disk_to_usr(inode, 0, 0, &cstr, &pstr);
  69         if (res)
  70                 goto errout;
  71
  72         /* Null-terminate the name */
  73         paddr[pstr.len] = '\0';
  74         if (cpage)
  75                 put_page(cpage);
  76         set_delayed_call(done, kfree_link, paddr);
  77         return paddr;
  78 errout:
  79         if (cpage)
  80                 put_page(cpage);
  81         kfree(paddr);
  82         return ERR_PTR(res);
  83 }
  84
  85 const struct inode_operations ext4_encrypted_symlink_inode_operations = {
  86         .readlink       = generic_readlink,
  87         .get_link       = ext4_encrypted_get_link,
  88         .setattr        = ext4_setattr,
  89         .listxattr      = ext4_listxattr,
  90 };
  91
  92 const struct inode_operations ext4_symlink_inode_operations = {
  93         .readlink       = generic_readlink,
  94         .get_link       = page_get_link,
  95         .setattr        = ext4_setattr,
  96         .listxattr      = ext4_listxattr,
  97 };
  98
  99 const struct inode_operations ext4_fast_symlink_inode_operations = {
 100         .readlink       = generic_readlink,
 101         .get_link       = simple_get_link,
 102         .setattr        = ext4_setattr,
 103         .listxattr      = ext4_listxattr,
 104 };