mirror of
https://github.com/Cisco-Talos/clamav.git
synced 2025-10-19 10:23:17 +00:00
31dcec1e42
Temp directory recursion in ClamAV is when each layer of a scan gets its
own temp directory in the parent layer's temp directory.
In addition to temp directory recursion, ClamAV has been creating a new
subdirectory for each file scan as a risk-adverse method to ensure
no temporary file leaks fill up the disk.
Creating a directory is relatively slow on Windows in particular if
scanning a lot of very small files.
This commit:
1. Separates the temp directory recursion feature from the leave-temps
feature so that libclamav can leave temp files without making
subdirectories for each file scanned.
2. Makes it so that when temp directory recursion is off, libclamav
will just use the configure temp directory for all files.
The new option to enable temp directory recursion is for libclamav-only
at this time. It is off by default, and you can enable it like this:
```c
cl_engine_set_num(engine, CL_ENGINE_TMPDIR_RECURSION, 1);
```
For the `clamscan` and `clamd` programs, temp directory recursion will
be enabled when `--leave-temps` / `LeaveTemporaryFiles` is enabled.
The difference is that when disabled, it will return to using the
configured temp directory without making a subdirectory for each file
scanned, so as to improve scan performance for small files, mostly on
Windows.
Under the hood, this commit also:
1. Cleans up how we keep track of tmpdirs for each layer.
The goal here is to align how we keep track of layer-specific stuff
using the scan_layer structure.
2. Cleans up how we record metadata JSON for embedded files.
Note: Embedded files being different from Contained files, as they
are extracted not with a parser, but by finding them with
file type magic signatures.
CLAM-1583
387 lines
13 KiB
C
387 lines
13 KiB
C
/*
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* Copyright (C) 2013-2025 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
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* Copyright (C) 2011-2013 Sourcefire, Inc.
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*
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* Authors: aCaB <acab@clamav.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA.
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*/
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#include <string.h>
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#include "clamav.h"
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#include "scanners.h"
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#include "iso9660.h"
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#include "fmap.h"
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#include "str.h"
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#include "entconv.h"
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#include "hashtab.h"
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typedef struct {
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cli_ctx *ctx;
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size_t base_offset;
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unsigned int blocksz;
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unsigned int sectsz;
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unsigned int fileno;
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unsigned int joliet;
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char buf[260];
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struct cli_hashset dir_blocks;
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} iso9660_t;
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static const void *needblock(const iso9660_t *iso, unsigned int block, int temp)
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{
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cli_ctx *ctx = iso->ctx;
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size_t loff;
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unsigned int blocks_per_sect = (2048 / iso->blocksz);
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if (block > ((ctx->fmap->len - iso->base_offset) / iso->sectsz) * blocks_per_sect)
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return NULL; /* Block is out of file */
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loff = (block / blocks_per_sect) * iso->sectsz; /* logical sector */
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loff += (block % blocks_per_sect) * iso->blocksz; /* logical block within the sector */
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if (temp)
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return fmap_need_off_once(ctx->fmap, iso->base_offset + loff, iso->blocksz);
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return fmap_need_off(ctx->fmap, iso->base_offset + loff, iso->blocksz);
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}
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static cl_error_t iso_scan_file(const iso9660_t *iso, unsigned int block, unsigned int len)
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{
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char *tmpf;
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int fd = -1;
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cl_error_t ret = CL_SUCCESS;
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if (cli_gentempfd(iso->ctx->this_layer_tmpdir, &tmpf, &fd) != CL_SUCCESS) {
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return CL_ETMPFILE;
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}
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cli_dbgmsg("iso_scan_file: dumping to %s\n", tmpf);
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while (len) {
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const void *buf = needblock(iso, block, 1);
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unsigned int todo = MIN(len, iso->blocksz);
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if (!buf) {
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/* Block outside file */
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cli_dbgmsg("iso_scan_file: cannot dump block outside file, ISO may be truncated\n");
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ret = CL_EFORMAT;
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break;
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}
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if (cli_writen(fd, buf, todo) != todo) {
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cli_warnmsg("iso_scan_file: Can't write to file %s\n", tmpf);
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ret = CL_EWRITE;
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break;
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}
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len -= todo;
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block++;
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}
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if (!len) {
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ret = cli_magic_scan_desc(fd, tmpf, iso->ctx, iso->buf, LAYER_ATTRIBUTES_NONE);
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}
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close(fd);
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if (!iso->ctx->engine->keeptmp) {
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if (cli_unlink(tmpf)) {
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ret = CL_EUNLINK;
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}
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}
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free(tmpf);
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return ret;
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}
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static char *iso_string(iso9660_t *iso, const void *src, unsigned int len)
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{
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if (iso->joliet) {
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char *utf8;
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const char *uutf8;
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if (len > (sizeof(iso->buf) - 2))
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len = sizeof(iso->buf) - 2;
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memcpy(iso->buf, src, len);
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iso->buf[len] = '\0';
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iso->buf[len + 1] = '\0';
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utf8 = cli_utf16_to_utf8(iso->buf, len, E_UTF16_BE);
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uutf8 = utf8 ? utf8 : "";
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strncpy(iso->buf, uutf8, sizeof(iso->buf));
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iso->buf[sizeof(iso->buf) - 1] = '\0';
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free(utf8);
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} else {
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memcpy(iso->buf, src, len);
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iso->buf[len] = '\0';
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}
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return iso->buf;
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}
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static cl_error_t iso_parse_dir(iso9660_t *iso, unsigned int block, unsigned int len)
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{
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cli_ctx *ctx = iso->ctx;
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cl_error_t ret = CL_SUCCESS;
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if (len < 34) {
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cli_dbgmsg("iso_parse_dir: Directory too small, skipping\n");
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return CL_SUCCESS;
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}
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for (; len && ret == CL_SUCCESS; block++, len -= MIN(len, iso->blocksz)) {
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const uint8_t *dir, *dir_orig;
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unsigned int dirsz;
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if (iso->dir_blocks.count > 1024) {
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cli_dbgmsg("iso_parse_dir: Breaking out due to too many dir records\n");
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return CL_BREAK;
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}
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if (cli_hashset_contains(&iso->dir_blocks, block)) {
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continue;
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}
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if (CL_SUCCESS != (ret = cli_hashset_addkey(&iso->dir_blocks, block))) {
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return ret;
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}
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dir = dir_orig = needblock(iso, block, 0);
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if (!dir) {
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return CL_SUCCESS;
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}
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for (dirsz = MIN(iso->blocksz, len);;) {
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unsigned int entrysz = *dir, fileoff, filesz;
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char *sep;
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if (!dirsz || !entrysz) /* continuing on next block, if any */
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break;
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if (entrysz > dirsz) { /* record size overlaps onto the next sector, no point in looking in there */
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cli_dbgmsg("iso_parse_dir: Directory entry overflow, breaking out %u %u\n", entrysz, dirsz);
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len = 0;
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break;
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}
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if (entrysz < 34) { /* this shouldn't happen really*/
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cli_dbgmsg("iso_parse_dir: Too short directory entry, attempting to skip\n");
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dirsz -= entrysz;
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dir += entrysz;
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continue;
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}
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filesz = dir[32];
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if (filesz == 1 && (dir[33] == 0 || dir[33] == 1)) { /* skip "." and ".." */
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dirsz -= entrysz;
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dir += entrysz;
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continue;
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}
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if (filesz + 33 > dirsz) {
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cli_dbgmsg("iso_parse_dir: Directory entry name overflow, clamping\n");
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filesz = dirsz - 33;
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}
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iso_string(iso, &dir[33], filesz);
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sep = memchr(iso->buf, ';', filesz);
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if (sep)
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*sep = '\0';
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else
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iso->buf[filesz] = '\0';
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fileoff = cli_readint32(dir + 2);
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fileoff += dir[1];
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filesz = cli_readint32(dir + 10);
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cli_dbgmsg("iso_parse_dir: %s '%s': off %x - size %x - flags %x - unit size %x - gap size %x - volume %u\n", (dir[25] & 2) ? "Directory" : "File", iso->buf, fileoff, filesz, dir[25], dir[26], dir[27], cli_readint32(&dir[28]) & 0xffff);
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ret = cli_matchmeta(ctx, iso->buf, filesz, filesz, 0, 0, 0);
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if (ret != CL_SUCCESS) {
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break;
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}
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if (dir[26] || dir[27])
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cli_dbgmsg("iso_parse_dir: Skipping interleaved file\n");
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else {
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/* TODO Handle multi-extent ? */
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if (dir[25] & 2) {
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ret = iso_parse_dir(iso, fileoff, filesz);
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} else {
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if (CL_SUCCESS != cli_checklimits("ISO9660", ctx, filesz, 0, 0)) {
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cli_dbgmsg("iso_parse_dir: Skipping overlimit file\n");
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} else {
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ret = iso_scan_file(iso, fileoff, filesz);
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}
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}
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if (ret != CL_SUCCESS) {
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break;
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}
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}
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dirsz -= entrysz;
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dir += entrysz;
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}
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fmap_unneed_ptr(ctx->fmap, dir_orig, iso->blocksz);
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}
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return ret;
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}
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cl_error_t cli_scaniso(cli_ctx *ctx, size_t offset)
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{
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const uint8_t *privol, *next;
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iso9660_t iso;
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int i;
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cl_error_t status = CL_SUCCESS;
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cl_error_t ret = CL_SUCCESS;
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uint32_t nextJoliet = 0;
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if (offset < 32768) {
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/* Need 16 sectors at least 2048 bytes long */
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goto done;
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}
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privol = fmap_need_off(ctx->fmap, offset, 2448 + 6);
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if (!privol) {
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goto done;
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}
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next = (uint8_t *)cli_memstr((char *)privol + 2049, 2448 + 6 - 2049, "CD001", 5);
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if (!next) {
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/* Find next volume descriptor */
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goto done;
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}
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iso.sectsz = (next - privol) - 1;
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if (iso.sectsz * 16 > offset) {
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/* Need room for 16 system sectors */
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goto done;
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}
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iso.blocksz = cli_readint32(privol + 128) & 0xffff;
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if (iso.blocksz != 512 && iso.blocksz != 1024 && iso.blocksz != 2048)
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/* Likely not a cdrom image */
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goto done;
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iso.base_offset = offset - iso.sectsz * 16;
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iso.joliet = 0;
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for (i = 16; i < 32; i++) { /* scan for a joliet secondary volume descriptor */
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next = fmap_need_off_once(ctx->fmap, iso.base_offset + i * iso.sectsz, 2048);
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if (!next)
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break; /* Out of disk */
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if (*next == 0xff || memcmp(next + 1, "CD001", 5))
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break; /* Not a volume descriptor */
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if (*next != 2)
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continue; /* Not a secondary volume descriptor */
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if (next[88] != 0x25 || next[89] != 0x2f)
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continue; /* Not a joliet descriptor */
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if (next[156 + 26] || next[156 + 27])
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continue; /* Root is interleaved so we fallback to the primary descriptor */
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switch (next[90]) {
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case 0x40: /* Level 1 */
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iso.joliet = 1;
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break;
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case 0x43: /* Level 2 */
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iso.joliet = 2;
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break;
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case 0x45: /* Level 3 */
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iso.joliet = 3;
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break;
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default: /* Not Joliet */
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continue;
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}
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break;
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}
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/* TODO rr, el torito, udf ? */
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/* NOTE: freeing sector now. it is still safe to access as we don't alloc anymore */
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fmap_unneed_off(ctx->fmap, offset, 2448);
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if (!iso.joliet) {
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next = NULL;
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}
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nextJoliet = iso.joliet;
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iso.joliet = 0;
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do {
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cli_dbgmsg("in cli_scaniso\n");
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if (cli_debug_flag) {
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cli_dbgmsg("cli_scaniso: Raw sector size: %u\n", iso.sectsz);
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cli_dbgmsg("cli_scaniso: Block size: %u\n", iso.blocksz);
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cli_dbgmsg("cli_scaniso: Volume descriptor version: %u\n", privol[6]);
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#define ISOSTRING(src, len) iso_string(&iso, (src), (len))
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cli_dbgmsg("cli_scaniso: System: %s\n", ISOSTRING(privol + 8, 32));
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cli_dbgmsg("cli_scaniso: Volume: %s\n", ISOSTRING(privol + 40, 32));
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cli_dbgmsg("cli_scaniso: Volume space size: 0x%x blocks\n", cli_readint32(&privol[80]));
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cli_dbgmsg("cli_scaniso: Volume %u of %u\n", cli_readint32(privol + 124) & 0xffff, cli_readint32(privol + 120) & 0xffff);
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cli_dbgmsg("cli_scaniso: Volume Set: %s\n", ISOSTRING(privol + 190, 128));
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cli_dbgmsg("cli_scaniso: Publisher: %s\n", ISOSTRING(privol + 318, 128));
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cli_dbgmsg("cli_scaniso: Data Preparer: %s\n", ISOSTRING(privol + 446, 128));
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cli_dbgmsg("cli_scaniso: Application: %s\n", ISOSTRING(privol + 574, 128));
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#define ISOTIME(s, n) cli_dbgmsg("cli_scaniso: "s \
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": %c%c%c%c-%c%c-%c%c %c%c:%c%c:%c%c\n", \
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privol[n], privol[n + 1], privol[n + 2], privol[n + 3], privol[n + 4], privol[n + 5], privol[n + 6], privol[n + 7], privol[n + 8], privol[n + 9], privol[n + 10], privol[n + 11], privol[n + 12], privol[n + 13])
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ISOTIME("Volume creation time", 813);
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ISOTIME("Volume modification time", 830);
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ISOTIME("Volume expiration time", 847);
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ISOTIME("Volume effective time", 864);
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cli_dbgmsg("cli_scaniso: Path table size: 0x%x\n", cli_readint32(privol + 132) & 0xffff);
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cli_dbgmsg("cli_scaniso: LSB Path Table: 0x%x\n", cli_readint32(privol + 140));
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cli_dbgmsg("cli_scaniso: Opt LSB Path Table: 0x%x\n", cli_readint32(privol + 144));
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cli_dbgmsg("cli_scaniso: MSB Path Table: 0x%x\n", cbswap32(cli_readint32(privol + 148)));
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cli_dbgmsg("cli_scaniso: Opt MSB Path Table: 0x%x\n", cbswap32(cli_readint32(privol + 152)));
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cli_dbgmsg("cli_scaniso: File Structure Version: %u\n", privol[881]);
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if (iso.joliet)
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cli_dbgmsg("cli_scaniso: Joliet level %u\n", iso.joliet);
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}
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if (privol[156 + 26] || privol[156 + 27]) {
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cli_dbgmsg("cli_scaniso: Interleaved root directory is not supported\n");
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status = CL_SUCCESS;
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goto done;
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}
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iso.ctx = ctx;
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ret = cli_hashset_init(&iso.dir_blocks, 1024, 80);
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if (ret != CL_SUCCESS) {
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status = ret;
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goto done;
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}
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ret = iso_parse_dir(&iso, cli_readint32(privol + 156 + 2) + privol[156 + 1], cli_readint32(privol + 156 + 10));
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cli_hashset_destroy(&iso.dir_blocks);
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switch (ret) {
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case CL_CLEAN:
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/* fallthrough */
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case CL_EFORMAT:
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/* fallthrough */
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case CL_EPARSE:
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break;
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default:
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/*Recoverable errors are above, anything else we need to return.*/
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status = ret;
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goto done;
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}
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if (ret > status) {
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status = ret;
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}
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privol = next;
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next = NULL;
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iso.joliet = nextJoliet;
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} while (privol);
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done:
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if (status == CL_BREAK) {
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status = CL_SUCCESS;
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}
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return status;
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}
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