1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2017-2018 HUAWEI, Inc. 4 * https://www.huawei.com/ 5 * Created by Gao Xiang <gaoxiang25@huawei.com> 6 */ 7 #include "internal.h" 8 9 static void debug_one_dentry(unsigned char d_type, const char *de_name, 10 unsigned int de_namelen) 11 { 12 #ifdef CONFIG_EROFS_FS_DEBUG 13 /* since the on-disk name could not have the trailing '\0' */ 14 unsigned char dbg_namebuf[EROFS_NAME_LEN + 1]; 15 16 memcpy(dbg_namebuf, de_name, de_namelen); 17 dbg_namebuf[de_namelen] = '\0'; 18 19 erofs_dbg("found dirent %s de_len %u d_type %d", dbg_namebuf, 20 de_namelen, d_type); 21 #endif 22 } 23 24 static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx, 25 void *dentry_blk, unsigned int *ofs, 26 unsigned int nameoff, unsigned int maxsize) 27 { 28 struct erofs_dirent *de = dentry_blk + *ofs; 29 const struct erofs_dirent *end = dentry_blk + nameoff; 30 31 while (de < end) { 32 const char *de_name; 33 unsigned int de_namelen; 34 unsigned char d_type; 35 36 d_type = fs_ftype_to_dtype(de->file_type); 37 38 nameoff = le16_to_cpu(de->nameoff); 39 de_name = (char *)dentry_blk + nameoff; 40 41 /* the last dirent in the block? */ 42 if (de + 1 >= end) 43 de_namelen = strnlen(de_name, maxsize - nameoff); 44 else 45 de_namelen = le16_to_cpu(de[1].nameoff) - nameoff; 46 47 /* a corrupted entry is found */ 48 if (nameoff + de_namelen > maxsize || 49 de_namelen > EROFS_NAME_LEN) { 50 erofs_err(dir->i_sb, "bogus dirent @ nid %llu", 51 EROFS_I(dir)->nid); 52 DBG_BUGON(1); 53 return -EFSCORRUPTED; 54 } 55 56 debug_one_dentry(d_type, de_name, de_namelen); 57 if (!dir_emit(ctx, de_name, de_namelen, 58 le64_to_cpu(de->nid), d_type)) 59 /* stopped by some reason */ 60 return 1; 61 ++de; 62 *ofs += sizeof(struct erofs_dirent); 63 } 64 *ofs = maxsize; 65 return 0; 66 } 67 68 static int erofs_readdir(struct file *f, struct dir_context *ctx) 69 { 70 struct inode *dir = file_inode(f); 71 struct address_space *mapping = dir->i_mapping; 72 const size_t dirsize = i_size_read(dir); 73 unsigned int i = ctx->pos / EROFS_BLKSIZ; 74 unsigned int ofs = ctx->pos % EROFS_BLKSIZ; 75 int err = 0; 76 bool initial = true; 77 78 while (ctx->pos < dirsize) { 79 struct page *dentry_page; 80 struct erofs_dirent *de; 81 unsigned int nameoff, maxsize; 82 83 dentry_page = read_mapping_page(mapping, i, NULL); 84 if (dentry_page == ERR_PTR(-ENOMEM)) { 85 err = -ENOMEM; 86 break; 87 } else if (IS_ERR(dentry_page)) { 88 erofs_err(dir->i_sb, 89 "fail to readdir of logical block %u of nid %llu", 90 i, EROFS_I(dir)->nid); 91 err = -EFSCORRUPTED; 92 break; 93 } 94 95 de = (struct erofs_dirent *)kmap(dentry_page); 96 97 nameoff = le16_to_cpu(de->nameoff); 98 99 if (nameoff < sizeof(struct erofs_dirent) || 100 nameoff >= PAGE_SIZE) { 101 erofs_err(dir->i_sb, 102 "invalid de[0].nameoff %u @ nid %llu", 103 nameoff, EROFS_I(dir)->nid); 104 err = -EFSCORRUPTED; 105 goto skip_this; 106 } 107 108 maxsize = min_t(unsigned int, 109 dirsize - ctx->pos + ofs, PAGE_SIZE); 110 111 /* search dirents at the arbitrary position */ 112 if (initial) { 113 initial = false; 114 115 ofs = roundup(ofs, sizeof(struct erofs_dirent)); 116 if (ofs >= nameoff) 117 goto skip_this; 118 } 119 120 err = erofs_fill_dentries(dir, ctx, de, &ofs, 121 nameoff, maxsize); 122 skip_this: 123 kunmap(dentry_page); 124 125 put_page(dentry_page); 126 127 ctx->pos = blknr_to_addr(i) + ofs; 128 129 if (err) 130 break; 131 ++i; 132 ofs = 0; 133 } 134 return err < 0 ? err : 0; 135 } 136 137 const struct file_operations erofs_dir_fops = { 138 .llseek = generic_file_llseek, 139 .read = generic_read_dir, 140 .iterate_shared = erofs_readdir, 141 }; 142 143