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_follow_link(struct dentry *dentry, void **cookie) 27 { 28 struct page *cpage = NULL; 29 char *caddr, *paddr = NULL; 30 struct ext4_str cstr, pstr; 31 struct inode *inode = d_inode(dentry); 32 struct ext4_encrypted_symlink_data *sd; 33 loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1); 34 int res; 35 u32 plen, max_size = inode->i_sb->s_blocksize; 36 37 res = ext4_get_encryption_info(inode); 38 if (res) 39 return ERR_PTR(res); 40 41 if (ext4_inode_is_fast_symlink(inode)) { 42 caddr = (char *) EXT4_I(inode)->i_data; 43 max_size = sizeof(EXT4_I(inode)->i_data); 44 } else { 45 cpage = read_mapping_page(inode->i_mapping, 0, NULL); 46 if (IS_ERR(cpage)) 47 return ERR_CAST(cpage); 48 caddr = kmap(cpage); 49 caddr[size] = 0; 50 } 51 52 /* Symlink is encrypted */ 53 sd = (struct ext4_encrypted_symlink_data *)caddr; 54 cstr.name = sd->encrypted_path; 55 cstr.len = le16_to_cpu(sd->len); 56 if ((cstr.len + 57 sizeof(struct ext4_encrypted_symlink_data) - 1) > 58 max_size) { 59 /* Symlink data on the disk is corrupted */ 60 res = -EFSCORRUPTED; 61 goto errout; 62 } 63 plen = (cstr.len < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2) ? 64 EXT4_FNAME_CRYPTO_DIGEST_SIZE*2 : cstr.len; 65 paddr = kmalloc(plen + 1, GFP_NOFS); 66 if (!paddr) { 67 res = -ENOMEM; 68 goto errout; 69 } 70 pstr.name = paddr; 71 pstr.len = plen; 72 res = _ext4_fname_disk_to_usr(inode, NULL, &cstr, &pstr); 73 if (res < 0) 74 goto errout; 75 /* Null-terminate the name */ 76 if (res <= plen) 77 paddr[res] = '\0'; 78 if (cpage) { 79 kunmap(cpage); 80 page_cache_release(cpage); 81 } 82 return *cookie = paddr; 83 errout: 84 if (cpage) { 85 kunmap(cpage); 86 page_cache_release(cpage); 87 } 88 kfree(paddr); 89 return ERR_PTR(res); 90 } 91 92 const struct inode_operations ext4_encrypted_symlink_inode_operations = { 93 .readlink = generic_readlink, 94 .follow_link = ext4_encrypted_follow_link, 95 .put_link = kfree_put_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 .follow_link = page_follow_link_light, 107 .put_link = page_put_link, 108 .setattr = ext4_setattr, 109 .setxattr = generic_setxattr, 110 .getxattr = generic_getxattr, 111 .listxattr = ext4_listxattr, 112 .removexattr = generic_removexattr, 113 }; 114 115 const struct inode_operations ext4_fast_symlink_inode_operations = { 116 .readlink = generic_readlink, 117 .follow_link = simple_follow_link, 118 .setattr = ext4_setattr, 119 .setxattr = generic_setxattr, 120 .getxattr = generic_getxattr, 121 .listxattr = ext4_listxattr, 122 .removexattr = generic_removexattr, 123 }; 124