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