![Eric Biggers](/assets/img/avatar_default.png)
In sprint_oid(), if the input buffer were to be more than 1 byte too
small for the first snprintf(), 'bufsize' would underflow, causing a
buffer overflow when printing the remainder of the OID.
Fortunately this cannot actually happen currently, because no users pass
in a buffer that can be too small for the first snprintf().
Regardless, fix it by checking the snprintf() return value correctly.
For consistency also tweak the second snprintf() check to look the same.
Fixes: 4f73175d03
("X.509: Add utility functions to render OIDs as strings")
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
176 lines
3.9 KiB
C
176 lines
3.9 KiB
C
/* ASN.1 Object identifier (OID) registry
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*
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* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <linux/export.h>
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#include <linux/oid_registry.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/bug.h>
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#include "oid_registry_data.c"
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MODULE_DESCRIPTION("OID Registry");
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MODULE_AUTHOR("Red Hat, Inc.");
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MODULE_LICENSE("GPL");
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/**
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* look_up_OID - Find an OID registration for the specified data
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* @data: Binary representation of the OID
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* @datasize: Size of the binary representation
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*/
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enum OID look_up_OID(const void *data, size_t datasize)
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{
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const unsigned char *octets = data;
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enum OID oid;
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unsigned char xhash;
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unsigned i, j, k, hash;
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size_t len;
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/* Hash the OID data */
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hash = datasize - 1;
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for (i = 0; i < datasize; i++)
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hash += octets[i] * 33;
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hash = (hash >> 24) ^ (hash >> 16) ^ (hash >> 8) ^ hash;
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hash &= 0xff;
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/* Binary search the OID registry. OIDs are stored in ascending order
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* of hash value then ascending order of size and then in ascending
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* order of reverse value.
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*/
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i = 0;
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k = OID__NR;
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while (i < k) {
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j = (i + k) / 2;
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xhash = oid_search_table[j].hash;
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if (xhash > hash) {
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k = j;
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continue;
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}
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if (xhash < hash) {
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i = j + 1;
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continue;
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}
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oid = oid_search_table[j].oid;
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len = oid_index[oid + 1] - oid_index[oid];
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if (len > datasize) {
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k = j;
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continue;
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}
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if (len < datasize) {
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i = j + 1;
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continue;
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}
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/* Variation is most likely to be at the tail end of the
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* OID, so do the comparison in reverse.
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*/
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while (len > 0) {
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unsigned char a = oid_data[oid_index[oid] + --len];
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unsigned char b = octets[len];
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if (a > b) {
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k = j;
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goto next;
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}
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if (a < b) {
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i = j + 1;
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goto next;
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}
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}
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return oid;
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next:
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;
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}
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return OID__NR;
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}
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EXPORT_SYMBOL_GPL(look_up_OID);
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/*
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* sprint_OID - Print an Object Identifier into a buffer
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* @data: The encoded OID to print
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* @datasize: The size of the encoded OID
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* @buffer: The buffer to render into
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* @bufsize: The size of the buffer
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*
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* The OID is rendered into the buffer in "a.b.c.d" format and the number of
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* bytes is returned. -EBADMSG is returned if the data could not be intepreted
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* and -ENOBUFS if the buffer was too small.
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*/
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int sprint_oid(const void *data, size_t datasize, char *buffer, size_t bufsize)
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{
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const unsigned char *v = data, *end = v + datasize;
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unsigned long num;
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unsigned char n;
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size_t ret;
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int count;
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if (v >= end)
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return -EBADMSG;
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n = *v++;
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ret = count = snprintf(buffer, bufsize, "%u.%u", n / 40, n % 40);
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if (count >= bufsize)
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return -ENOBUFS;
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buffer += count;
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bufsize -= count;
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while (v < end) {
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num = 0;
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n = *v++;
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if (!(n & 0x80)) {
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num = n;
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} else {
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num = n & 0x7f;
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do {
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if (v >= end)
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return -EBADMSG;
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n = *v++;
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num <<= 7;
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num |= n & 0x7f;
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} while (n & 0x80);
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}
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ret += count = snprintf(buffer, bufsize, ".%lu", num);
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if (count >= bufsize)
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return -ENOBUFS;
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buffer += count;
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bufsize -= count;
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(sprint_oid);
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/**
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* sprint_OID - Print an Object Identifier into a buffer
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* @oid: The OID to print
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* @buffer: The buffer to render into
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* @bufsize: The size of the buffer
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*
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* The OID is rendered into the buffer in "a.b.c.d" format and the number of
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* bytes is returned.
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*/
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int sprint_OID(enum OID oid, char *buffer, size_t bufsize)
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{
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int ret;
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BUG_ON(oid >= OID__NR);
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ret = sprint_oid(oid_data + oid_index[oid],
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oid_index[oid + 1] - oid_index[oid],
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buffer, bufsize);
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BUG_ON(ret == -EBADMSG);
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return ret;
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}
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EXPORT_SYMBOL_GPL(sprint_OID);
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