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 }; 118