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 #ifdef CONFIG_EXT4_FS_ENCRYPTION
  26 static const char *ext4_encrypted_get_link(struct dentry *dentry,
  27                                            struct inode *inode,
  28                                            struct delayed_call *done)
  29 {
  30         struct page *cpage = NULL;
  31         char *caddr, *paddr = NULL;
  32         struct ext4_str cstr, pstr;
  33         struct ext4_encrypted_symlink_data *sd;
  34         loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
  35         int res;
  36         u32 plen, max_size = inode->i_sb->s_blocksize;
  37
  38         if (!dentry)
  39                 return ERR_PTR(-ECHILD);
  40
  41         res = ext4_get_encryption_info(inode);
  42         if (res)
  43                 return ERR_PTR(res);
  44
  45         if (ext4_inode_is_fast_symlink(inode)) {
  46                 caddr = (char *) EXT4_I(inode)->i_data;
  47                 max_size = sizeof(EXT4_I(inode)->i_data);
  48         } else {
  49                 cpage = read_mapping_page(inode->i_mapping, 0, NULL);
  50                 if (IS_ERR(cpage))
  51                         return ERR_CAST(cpage);
  52                 caddr = page_address(cpage);
  53                 caddr[size] = 0;
  54         }
  55
  56         /* Symlink is encrypted */
  57         sd = (struct ext4_encrypted_symlink_data *)caddr;
  58         cstr.name = sd->encrypted_path;
  59         cstr.len  = le16_to_cpu(sd->len);
  60         if ((cstr.len +
  61              sizeof(struct ext4_encrypted_symlink_data) - 1) >
  62             max_size) {
  63                 /* Symlink data on the disk is corrupted */
  64                 res = -EFSCORRUPTED;
  65                 goto errout;
  66         }
  67         plen = (cstr.len < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2) ?
  68                 EXT4_FNAME_CRYPTO_DIGEST_SIZE*2 : cstr.len;
  69         paddr = kmalloc(plen + 1, GFP_NOFS);
  70         if (!paddr) {
  71                 res = -ENOMEM;
  72                 goto errout;
  73         }
  74         pstr.name = paddr;
  75         pstr.len = plen;
  76         res = _ext4_fname_disk_to_usr(inode, NULL, &cstr, &pstr);
  77         if (res < 0)
  78                 goto errout;
  79         /* Null-terminate the name */
  80         if (res <= plen)
  81                 paddr[res] = '\0';
  82         if (cpage)
  83                 page_cache_release(cpage);
  84         set_delayed_call(done, kfree_link, paddr);
  85         return paddr;
  86 errout:
  87         if (cpage)
  88                 page_cache_release(cpage);
  89         kfree(paddr);
  90         return ERR_PTR(res);
  91 }
  92
  93 const struct inode_operations ext4_encrypted_symlink_inode_operations = {
  94         .readlink       = generic_readlink,
  95         .get_link       = ext4_encrypted_get_link,
  96         .setattr        = ext4_setattr,
  97         .setxattr       = generic_setxattr,
  98         .getxattr       = generic_getxattr,
  99         .listxattr      = ext4_listxattr,
 100         .removexattr    = generic_removexattr,
 101 };
 102 #endif
 103
 104 const struct inode_operations ext4_symlink_inode_operations = {
 105         .readlink       = generic_readlink,
 106         .get_link       = page_get_link,
 107         .setattr        = ext4_setattr,
 108         .setxattr       = generic_setxattr,
 109         .getxattr       = generic_getxattr,
 110         .listxattr      = ext4_listxattr,
 111         .removexattr    = generic_removexattr,
 112 };
 113
 114 const struct inode_operations ext4_fast_symlink_inode_operations = {
 115         .readlink       = generic_readlink,
 116         .get_link       = simple_get_link,
 117         .setattr        = ext4_setattr,
 118         .setxattr       = generic_setxattr,
 119         .getxattr       = generic_getxattr,
 120         .listxattr      = ext4_listxattr,
 121         .removexattr    = generic_removexattr,
 122 };