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_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_fname_crypto_ctx *ctx = NULL; 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 ctx = ext4_get_fname_crypto_ctx(inode, inode->i_sb->s_blocksize); 39 if (IS_ERR(ctx)) 40 return ERR_CAST(ctx); 41 42 if (ext4_inode_is_fast_symlink(inode)) { 43 caddr = (char *) EXT4_I(inode)->i_data; 44 max_size = sizeof(EXT4_I(inode)->i_data); 45 } else { 46 cpage = read_mapping_page(inode->i_mapping, 0, NULL); 47 if (IS_ERR(cpage)) { 48 ext4_put_fname_crypto_ctx(&ctx); 49 return ERR_CAST(cpage); 50 } 51 caddr = kmap(cpage); 52 caddr[size] = 0; 53 } 54 55 /* Symlink is encrypted */ 56 sd = (struct ext4_encrypted_symlink_data *)caddr; 57 cstr.name = sd->encrypted_path; 58 cstr.len = le32_to_cpu(sd->len); 59 if ((cstr.len + 60 sizeof(struct ext4_encrypted_symlink_data) - 1) > 61 max_size) { 62 /* Symlink data on the disk is corrupted */ 63 res = -EIO; 64 goto errout; 65 } 66 plen = (cstr.len < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2) ? 67 EXT4_FNAME_CRYPTO_DIGEST_SIZE*2 : cstr.len; 68 paddr = kmalloc(plen + 1, GFP_NOFS); 69 if (!paddr) { 70 res = -ENOMEM; 71 goto errout; 72 } 73 pstr.name = paddr; 74 res = _ext4_fname_disk_to_usr(ctx, NULL, &cstr, &pstr); 75 if (res < 0) 76 goto errout; 77 /* Null-terminate the name */ 78 if (res <= plen) 79 paddr[res] = '\0'; 80 ext4_put_fname_crypto_ctx(&ctx); 81 if (cpage) { 82 kunmap(cpage); 83 page_cache_release(cpage); 84 } 85 return *cookie = paddr; 86 errout: 87 ext4_put_fname_crypto_ctx(&ctx); 88 if (cpage) { 89 kunmap(cpage); 90 page_cache_release(cpage); 91 } 92 kfree(paddr); 93 return ERR_PTR(res); 94 } 95 96 const struct inode_operations ext4_encrypted_symlink_inode_operations = { 97 .readlink = generic_readlink, 98 .follow_link = ext4_follow_link, 99 .put_link = kfree_put_link, 100 .setattr = ext4_setattr, 101 .setxattr = generic_setxattr, 102 .getxattr = generic_getxattr, 103 .listxattr = ext4_listxattr, 104 .removexattr = generic_removexattr, 105 }; 106 #endif 107 108 const struct inode_operations ext4_symlink_inode_operations = { 109 .readlink = generic_readlink, 110 .follow_link = page_follow_link_light, 111 .put_link = page_put_link, 112 .setattr = ext4_setattr, 113 .setxattr = generic_setxattr, 114 .getxattr = generic_getxattr, 115 .listxattr = ext4_listxattr, 116 .removexattr = generic_removexattr, 117 }; 118 119 const struct inode_operations ext4_fast_symlink_inode_operations = { 120 .readlink = generic_readlink, 121 .follow_link = simple_follow_link, 122 .setattr = ext4_setattr, 123 .setxattr = generic_setxattr, 124 .getxattr = generic_getxattr, 125 .listxattr = ext4_listxattr, 126 .removexattr = generic_removexattr, 127 }; 128