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         loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
  34         int res;
  35         u32 max_size = inode->i_sb->s_blocksize;
  36
  37         if (!dentry)
  38                 return ERR_PTR(-ECHILD);
  39
  40         res = fscrypt_get_encryption_info(inode);
  41         if (res)
  42                 return ERR_PTR(res);
  43
  44         if (ext4_inode_is_fast_symlink(inode)) {
  45                 caddr = (char *) EXT4_I(inode)->i_data;
  46                 max_size = sizeof(EXT4_I(inode)->i_data);
  47         } else {
  48                 cpage = read_mapping_page(inode->i_mapping, 0, NULL);
  49                 if (IS_ERR(cpage))
  50                         return ERR_CAST(cpage);
  51                 caddr = page_address(cpage);
  52                 caddr[size] = 0;
  53         }
  54
  55         /* Symlink is encrypted */
  56         sd = (struct fscrypt_symlink_data *)caddr;
  57         cstr.name = sd->encrypted_path;
  58         cstr.len  = le16_to_cpu(sd->len);
  59         if ((cstr.len + sizeof(struct fscrypt_symlink_data) - 1) > max_size) {
  60                 /* Symlink data on the disk is corrupted */
  61                 res = -EFSCORRUPTED;
  62                 goto errout;
  63         }
  64
  65         res = fscrypt_fname_alloc_buffer(inode, cstr.len, &pstr);
  66         if (res)
  67                 goto errout;
  68
  69         res = fscrypt_fname_disk_to_usr(inode, 0, 0, &cstr, &pstr);
  70         if (res < 0)
  71                 goto errout;
  72
  73         paddr = pstr.name;
  74
  75         /* Null-terminate the name */
  76         if (res <= pstr.len)
  77                 paddr[res] = '\0';
  78         if (cpage)
  79                 put_page(cpage);
  80         set_delayed_call(done, kfree_link, paddr);
  81         return paddr;
  82 errout:
  83         if (cpage)
  84                 put_page(cpage);
  85         kfree(paddr);
  86         return ERR_PTR(res);
  87 }
  88
  89 const struct inode_operations ext4_encrypted_symlink_inode_operations = {
  90         .readlink       = generic_readlink,
  91         .get_link       = ext4_encrypted_get_link,
  92         .setattr        = ext4_setattr,
  93         .setxattr       = generic_setxattr,
  94         .getxattr       = generic_getxattr,
  95         .listxattr      = ext4_listxattr,
  96         .removexattr    = generic_removexattr,
  97 };
  98
  99 const struct inode_operations ext4_symlink_inode_operations = {
 100         .readlink       = generic_readlink,
 101         .get_link       = page_get_link,
 102         .setattr        = ext4_setattr,
 103         .setxattr       = generic_setxattr,
 104         .getxattr       = generic_getxattr,
 105         .listxattr      = ext4_listxattr,
 106         .removexattr    = generic_removexattr,
 107 };
 108
 109 const struct inode_operations ext4_fast_symlink_inode_operations = {
 110         .readlink       = generic_readlink,
 111         .get_link       = simple_get_link,
 112         .setattr        = ext4_setattr,
 113         .setxattr       = generic_setxattr,
 114         .getxattr       = generic_getxattr,
 115         .listxattr      = ext4_listxattr,
 116         .removexattr    = generic_removexattr,
 117 };