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 buffer_head *bh = NULL;
  31         const void *caddr;
  32         unsigned int max_size;
  33         const char *paddr;
  34
  35         if (!dentry)
  36                 return ERR_PTR(-ECHILD);
  37
  38         if (ext4_inode_is_fast_symlink(inode)) {
  39                 caddr = EXT4_I(inode)->i_data;
  40                 max_size = sizeof(EXT4_I(inode)->i_data);
  41         } else {
  42                 bh = ext4_bread(NULL, inode, 0, 0);
  43                 if (IS_ERR(bh))
  44                         return ERR_CAST(bh);
  45                 if (!bh) {
  46                         EXT4_ERROR_INODE(inode, "bad symlink.");
  47                         return ERR_PTR(-EFSCORRUPTED);
  48                 }
  49                 caddr = bh->b_data;
  50                 max_size = inode->i_sb->s_blocksize;
  51         }
  52
  53         paddr = fscrypt_get_symlink(inode, caddr, max_size, done);
  54         brelse(bh);
  55         return paddr;
  56 }
  57
  58 static int ext4_encrypted_symlink_getattr(struct user_namespace *mnt_userns,
  59                                           const struct path *path,
  60                                           struct kstat *stat, u32 request_mask,
  61                                           unsigned int query_flags)
  62 {
  63         ext4_getattr(mnt_userns, path, stat, request_mask, query_flags);
  64
  65         return fscrypt_symlink_getattr(path, stat);
  66 }
  67
  68 static void ext4_free_link(void *bh)
  69 {
  70         brelse(bh);
  71 }
  72
  73 static const char *ext4_get_link(struct dentry *dentry, struct inode *inode,
  74                                  struct delayed_call *callback)
  75 {
  76         struct buffer_head *bh;
  77         char *inline_link;
  78
  79         /*
  80          * Create a new inlined symlink is not supported, just provide a
  81          * method to read the leftovers.
  82          */
  83         if (ext4_has_inline_data(inode)) {
  84                 if (!dentry)
  85                         return ERR_PTR(-ECHILD);
  86
  87                 inline_link = ext4_read_inline_link(inode);
  88                 if (!IS_ERR(inline_link))
  89                         set_delayed_call(callback, kfree_link, inline_link);
  90                 return inline_link;
  91         }
  92
  93         if (!dentry) {
  94                 bh = ext4_getblk(NULL, inode, 0, EXT4_GET_BLOCKS_CACHED_NOWAIT);
  95                 if (IS_ERR(bh))
  96                         return ERR_CAST(bh);
  97                 if (!bh || !ext4_buffer_uptodate(bh))
  98                         return ERR_PTR(-ECHILD);
  99         } else {
 100                 bh = ext4_bread(NULL, inode, 0, 0);
 101                 if (IS_ERR(bh))
 102                         return ERR_CAST(bh);
 103                 if (!bh) {
 104                         EXT4_ERROR_INODE(inode, "bad symlink.");
 105                         return ERR_PTR(-EFSCORRUPTED);
 106                 }
 107         }
 108
 109         set_delayed_call(callback, ext4_free_link, bh);
 110         nd_terminate_link(bh->b_data, inode->i_size,
 111                           inode->i_sb->s_blocksize - 1);
 112         return bh->b_data;
 113 }
 114
 115 const struct inode_operations ext4_encrypted_symlink_inode_operations = {
 116         .get_link       = ext4_encrypted_get_link,
 117         .setattr        = ext4_setattr,
 118         .getattr        = ext4_encrypted_symlink_getattr,
 119         .listxattr      = ext4_listxattr,
 120 };
 121
 122 const struct inode_operations ext4_symlink_inode_operations = {
 123         .get_link       = ext4_get_link,
 124         .setattr        = ext4_setattr,
 125         .getattr        = ext4_getattr,
 126         .listxattr      = ext4_listxattr,
 127 };
 128
 129 const struct inode_operations ext4_fast_symlink_inode_operations = {
 130         .get_link       = simple_get_link,
 131         .setattr        = ext4_setattr,
 132         .getattr        = ext4_getattr,
 133         .listxattr      = ext4_listxattr,
 134 };