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 }; 106