fs/ext4/symlink.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/ext4/symlink.c
   4  *
   5  * Only fast symlinks left here - the rest is done by generic code. AV, 1999
   6  *
   7  * Copyright (C) 1992, 1993, 1994, 1995
   8  * Remy Card (card@masi.ibp.fr)
   9  * Laboratoire MASI - Institut Blaise Pascal
  10  * Universite Pierre et Marie Curie (Paris VI)
  11  *
  12  *  from
  13  *
  14  *  linux/fs/minix/symlink.c
  15  *
  16  *  Copyright (C) 1991, 1992  Linus Torvalds
  17  *
  18  *  ext4 symlink handling code
  19  */
  20
  21 #include <linux/fs.h>
  22 #include <linux/namei.h>
  23 #include "ext4.h"
  24 #include "xattr.h"
  25
  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 fscrypt_str cstr, pstr;
  33         struct fscrypt_symlink_data *sd;
  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         }
  53
  54         /* Symlink is encrypted */
  55         sd = (struct fscrypt_symlink_data *)caddr;
  56         cstr.name = sd->encrypted_path;
  57         cstr.len  = le16_to_cpu(sd->len);
  58         if ((cstr.len + sizeof(struct fscrypt_symlink_data) - 1) > max_size) {
  59                 /* Symlink data on the disk is corrupted */
  60                 res = -EFSCORRUPTED;
  61                 goto errout;
  62         }
  63
  64         res = fscrypt_fname_alloc_buffer(inode, cstr.len, &pstr);
  65         if (res)
  66                 goto errout;
  67         paddr = pstr.name;
  68
  69         res = fscrypt_fname_disk_to_usr(inode, 0, 0, &cstr, &pstr);
  70         if (res)
  71                 goto errout;
  72
  73         /* Null-terminate the name */
  74         paddr[pstr.len] = '\0';
  75         if (cpage)
  76                 put_page(cpage);
  77         set_delayed_call(done, kfree_link, paddr);
  78         return paddr;
  79 errout:
  80         if (cpage)
  81                 put_page(cpage);
  82         kfree(paddr);
  83         return ERR_PTR(res);
  84 }
  85
  86 const struct inode_operations ext4_encrypted_symlink_inode_operations = {
  87         .get_link       = ext4_encrypted_get_link,
  88         .setattr        = ext4_setattr,
  89         .getattr        = ext4_getattr,
  90         .listxattr      = ext4_listxattr,
  91 };
  92
  93 const struct inode_operations ext4_symlink_inode_operations = {
  94         .get_link       = page_get_link,
  95         .setattr        = ext4_setattr,
  96         .getattr        = ext4_getattr,
  97         .listxattr      = ext4_listxattr,
  98 };
  99
 100 const struct inode_operations ext4_fast_symlink_inode_operations = {
 101         .get_link       = simple_get_link,
 102         .setattr        = ext4_setattr,
 103         .getattr        = ext4_getattr,
 104         .listxattr      = ext4_listxattr,
 105 };