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 put_page(cpage); 84 set_delayed_call(done, kfree_link, paddr); 85 return paddr; 86 errout: 87 if (cpage) 88 put_page(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 }; 123