394 lines
10 KiB
C
394 lines
10 KiB
C
/*
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* Copyright (C) 2013 Politecnico di Torino, Italy
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* TORSEC group -- http://security.polito.it
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*
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* Author: Roberto Sassu <roberto.sassu@polito.it>
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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 License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*
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* File: ima_template_lib.c
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* Library of supported template fields.
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*/
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#include "ima_template_lib.h"
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static bool ima_template_hash_algo_allowed(u8 algo)
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{
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if (algo == HASH_ALGO_SHA1 || algo == HASH_ALGO_MD5)
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return true;
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return false;
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}
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enum data_formats {
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DATA_FMT_DIGEST = 0,
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DATA_FMT_DIGEST_WITH_ALGO,
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DATA_FMT_STRING,
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DATA_FMT_HEX
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};
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static int ima_write_template_field_data(const void *data, const u32 datalen,
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enum data_formats datafmt,
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struct ima_field_data *field_data)
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{
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u8 *buf, *buf_ptr;
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u32 buflen = datalen;
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if (datafmt == DATA_FMT_STRING)
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buflen = datalen + 1;
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buf = kzalloc(buflen, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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memcpy(buf, data, datalen);
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/*
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* Replace all space characters with underscore for event names and
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* strings. This avoid that, during the parsing of a measurements list,
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* filenames with spaces or that end with the suffix ' (deleted)' are
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* split into multiple template fields (the space is the delimitator
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* character for measurements lists in ASCII format).
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*/
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if (datafmt == DATA_FMT_STRING) {
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for (buf_ptr = buf; buf_ptr - buf < datalen; buf_ptr++)
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if (*buf_ptr == ' ')
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*buf_ptr = '_';
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}
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field_data->data = buf;
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field_data->len = buflen;
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return 0;
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}
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static void ima_show_template_data_ascii(struct seq_file *m,
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enum ima_show_type show,
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enum data_formats datafmt,
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struct ima_field_data *field_data)
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{
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u8 *buf_ptr = field_data->data;
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u32 buflen = field_data->len;
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switch (datafmt) {
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case DATA_FMT_DIGEST_WITH_ALGO:
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buf_ptr = strnchr(field_data->data, buflen, ':');
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if (buf_ptr != field_data->data)
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seq_printf(m, "%s", field_data->data);
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/* skip ':' and '\0' */
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buf_ptr += 2;
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buflen -= buf_ptr - field_data->data;
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case DATA_FMT_DIGEST:
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case DATA_FMT_HEX:
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if (!buflen)
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break;
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ima_print_digest(m, buf_ptr, buflen);
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break;
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case DATA_FMT_STRING:
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seq_printf(m, "%s", buf_ptr);
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break;
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default:
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break;
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}
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}
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static void ima_show_template_data_binary(struct seq_file *m,
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enum ima_show_type show,
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enum data_formats datafmt,
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struct ima_field_data *field_data)
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{
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u32 len = (show == IMA_SHOW_BINARY_OLD_STRING_FMT) ?
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strlen(field_data->data) : field_data->len;
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if (show != IMA_SHOW_BINARY_NO_FIELD_LEN) {
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u32 field_len = !ima_canonical_fmt ? len : cpu_to_le32(len);
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ima_putc(m, &field_len, sizeof(field_len));
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}
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if (!len)
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return;
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ima_putc(m, field_data->data, len);
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}
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static void ima_show_template_field_data(struct seq_file *m,
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enum ima_show_type show,
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enum data_formats datafmt,
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struct ima_field_data *field_data)
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{
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switch (show) {
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case IMA_SHOW_ASCII:
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ima_show_template_data_ascii(m, show, datafmt, field_data);
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break;
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case IMA_SHOW_BINARY:
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case IMA_SHOW_BINARY_NO_FIELD_LEN:
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case IMA_SHOW_BINARY_OLD_STRING_FMT:
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ima_show_template_data_binary(m, show, datafmt, field_data);
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break;
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default:
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break;
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}
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}
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void ima_show_template_digest(struct seq_file *m, enum ima_show_type show,
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struct ima_field_data *field_data)
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{
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ima_show_template_field_data(m, show, DATA_FMT_DIGEST, field_data);
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}
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void ima_show_template_digest_ng(struct seq_file *m, enum ima_show_type show,
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struct ima_field_data *field_data)
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{
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ima_show_template_field_data(m, show, DATA_FMT_DIGEST_WITH_ALGO,
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field_data);
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}
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void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
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struct ima_field_data *field_data)
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{
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ima_show_template_field_data(m, show, DATA_FMT_STRING, field_data);
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}
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void ima_show_template_sig(struct seq_file *m, enum ima_show_type show,
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struct ima_field_data *field_data)
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{
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ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
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}
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/**
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* ima_parse_buf() - Parses lengths and data from an input buffer
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* @bufstartp: Buffer start address.
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* @bufendp: Buffer end address.
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* @bufcurp: Pointer to remaining (non-parsed) data.
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* @maxfields: Length of fields array.
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* @fields: Array containing lengths and pointers of parsed data.
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* @curfields: Number of array items containing parsed data.
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* @len_mask: Bitmap (if bit is set, data length should not be parsed).
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* @enforce_mask: Check if curfields == maxfields and/or bufcurp == bufendp.
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* @bufname: String identifier of the input buffer.
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*
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* Return: 0 on success, -EINVAL on error.
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*/
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int ima_parse_buf(void *bufstartp, void *bufendp, void **bufcurp,
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int maxfields, struct ima_field_data *fields, int *curfields,
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unsigned long *len_mask, int enforce_mask, char *bufname)
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{
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void *bufp = bufstartp;
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int i;
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for (i = 0; i < maxfields; i++) {
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if (len_mask == NULL || !test_bit(i, len_mask)) {
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if (bufp > (bufendp - sizeof(u32)))
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break;
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fields[i].len = *(u32 *)bufp;
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if (ima_canonical_fmt)
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fields[i].len = le32_to_cpu(fields[i].len);
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bufp += sizeof(u32);
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}
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if (bufp > (bufendp - fields[i].len))
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break;
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fields[i].data = bufp;
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bufp += fields[i].len;
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}
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if ((enforce_mask & ENFORCE_FIELDS) && i != maxfields) {
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pr_err("%s: nr of fields mismatch: expected: %d, current: %d\n",
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bufname, maxfields, i);
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return -EINVAL;
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}
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if ((enforce_mask & ENFORCE_BUFEND) && bufp != bufendp) {
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pr_err("%s: buf end mismatch: expected: %p, current: %p\n",
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bufname, bufendp, bufp);
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return -EINVAL;
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}
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if (curfields)
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*curfields = i;
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if (bufcurp)
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*bufcurp = bufp;
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return 0;
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}
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static int ima_eventdigest_init_common(u8 *digest, u32 digestsize, u8 hash_algo,
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struct ima_field_data *field_data)
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{
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/*
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* digest formats:
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* - DATA_FMT_DIGEST: digest
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* - DATA_FMT_DIGEST_WITH_ALGO: [<hash algo>] + ':' + '\0' + digest,
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* where <hash algo> is provided if the hash algoritm is not
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* SHA1 or MD5
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*/
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u8 buffer[CRYPTO_MAX_ALG_NAME + 2 + IMA_MAX_DIGEST_SIZE] = { 0 };
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enum data_formats fmt = DATA_FMT_DIGEST;
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u32 offset = 0;
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if (hash_algo < HASH_ALGO__LAST) {
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fmt = DATA_FMT_DIGEST_WITH_ALGO;
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offset += snprintf(buffer, CRYPTO_MAX_ALG_NAME + 1, "%s",
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hash_algo_name[hash_algo]);
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buffer[offset] = ':';
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offset += 2;
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}
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if (digest)
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memcpy(buffer + offset, digest, digestsize);
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else
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/*
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* If digest is NULL, the event being recorded is a violation.
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* Make room for the digest by increasing the offset of
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* IMA_DIGEST_SIZE.
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*/
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offset += IMA_DIGEST_SIZE;
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return ima_write_template_field_data(buffer, offset + digestsize,
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fmt, field_data);
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}
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/*
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* This function writes the digest of an event (with size limit).
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*/
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int ima_eventdigest_init(struct ima_event_data *event_data,
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struct ima_field_data *field_data)
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{
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struct {
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struct ima_digest_data hdr;
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char digest[IMA_MAX_DIGEST_SIZE];
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} hash;
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u8 *cur_digest = NULL;
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u32 cur_digestsize = 0;
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struct inode *inode;
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int result;
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memset(&hash, 0, sizeof(hash));
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if (event_data->violation) /* recording a violation. */
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goto out;
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if (ima_template_hash_algo_allowed(event_data->iint->ima_hash->algo)) {
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cur_digest = event_data->iint->ima_hash->digest;
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cur_digestsize = event_data->iint->ima_hash->length;
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goto out;
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}
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if (!event_data->file) /* missing info to re-calculate the digest */
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return -EINVAL;
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inode = file_inode(event_data->file);
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hash.hdr.algo = ima_template_hash_algo_allowed(ima_hash_algo) ?
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ima_hash_algo : HASH_ALGO_SHA1;
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result = ima_calc_file_hash(event_data->file, &hash.hdr);
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if (result) {
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integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
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event_data->filename, "collect_data",
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"failed", result, 0);
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return result;
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}
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cur_digest = hash.hdr.digest;
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cur_digestsize = hash.hdr.length;
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out:
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return ima_eventdigest_init_common(cur_digest, cur_digestsize,
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HASH_ALGO__LAST, field_data);
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}
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/*
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* This function writes the digest of an event (without size limit).
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*/
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int ima_eventdigest_ng_init(struct ima_event_data *event_data,
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struct ima_field_data *field_data)
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{
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u8 *cur_digest = NULL, hash_algo = HASH_ALGO_SHA1;
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u32 cur_digestsize = 0;
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if (event_data->violation) /* recording a violation. */
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goto out;
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cur_digest = event_data->iint->ima_hash->digest;
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cur_digestsize = event_data->iint->ima_hash->length;
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hash_algo = event_data->iint->ima_hash->algo;
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out:
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return ima_eventdigest_init_common(cur_digest, cur_digestsize,
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hash_algo, field_data);
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}
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static int ima_eventname_init_common(struct ima_event_data *event_data,
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struct ima_field_data *field_data,
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bool size_limit)
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{
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const char *cur_filename = NULL;
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u32 cur_filename_len = 0;
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BUG_ON(event_data->filename == NULL && event_data->file == NULL);
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if (event_data->filename) {
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cur_filename = event_data->filename;
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cur_filename_len = strlen(event_data->filename);
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if (!size_limit || cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
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goto out;
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}
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if (event_data->file) {
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cur_filename = event_data->file->f_path.dentry->d_name.name;
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cur_filename_len = strlen(cur_filename);
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} else
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/*
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* Truncate filename if the latter is too long and
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* the file descriptor is not available.
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*/
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cur_filename_len = IMA_EVENT_NAME_LEN_MAX;
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out:
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return ima_write_template_field_data(cur_filename, cur_filename_len,
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DATA_FMT_STRING, field_data);
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}
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/*
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* This function writes the name of an event (with size limit).
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*/
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int ima_eventname_init(struct ima_event_data *event_data,
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struct ima_field_data *field_data)
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{
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return ima_eventname_init_common(event_data, field_data, true);
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}
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/*
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* This function writes the name of an event (without size limit).
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*/
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int ima_eventname_ng_init(struct ima_event_data *event_data,
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struct ima_field_data *field_data)
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{
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return ima_eventname_init_common(event_data, field_data, false);
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}
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/*
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* ima_eventsig_init - include the file signature as part of the template data
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*/
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int ima_eventsig_init(struct ima_event_data *event_data,
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struct ima_field_data *field_data)
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{
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enum data_formats fmt = DATA_FMT_HEX;
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struct evm_ima_xattr_data *xattr_value = event_data->xattr_value;
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int xattr_len = event_data->xattr_len;
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int rc = 0;
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if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
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goto out;
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rc = ima_write_template_field_data(xattr_value, xattr_len, fmt,
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field_data);
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out:
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return rc;
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}
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