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![Mimi Zohar](/assets/img/avatar_default.png)
The IMA binary_runtime_measurements list is currently in platform native format. To allow restoring a measurement list carried across kexec with a different endianness than the targeted kernel, this patch defines little-endian as the canonical format. For big endian systems wanting to save/restore the measurement list from a system with a different endianness, a new boot command line parameter named "ima_canonical_fmt" is defined. Considerations: use of the "ima_canonical_fmt" boot command line option will break existing userspace applications on big endian systems expecting the binary_runtime_measurements list to be in platform native format. Link: http://lkml.kernel.org/r/1480554346-29071-10-git-send-email-zohar@linux.vnet.ibm.com Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> Acked-by: Dmitry Kasatkin <dmitry.kasatkin@gmail.com> Cc: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Andreas Steffen <andreas.steffen@strongswan.org> Cc: Josh Sklar <sklar@linux.vnet.ibm.com> Cc: Dave Young <dyoung@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Baoquan He <bhe@redhat.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Stewart Smith <stewart@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
168 lines
4.2 KiB
C
168 lines
4.2 KiB
C
/*
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* Copyright (C) 2016 IBM Corporation
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*
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* Authors:
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* Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
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* Mimi Zohar <zohar@linux.vnet.ibm.com>
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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 as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/seq_file.h>
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#include <linux/vmalloc.h>
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#include <linux/kexec.h>
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#include "ima.h"
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#ifdef CONFIG_IMA_KEXEC
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static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
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unsigned long segment_size)
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{
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struct ima_queue_entry *qe;
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struct seq_file file;
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struct ima_kexec_hdr khdr;
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int ret = 0;
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/* segment size can't change between kexec load and execute */
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file.buf = vmalloc(segment_size);
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if (!file.buf) {
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ret = -ENOMEM;
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goto out;
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}
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file.size = segment_size;
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file.read_pos = 0;
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file.count = sizeof(khdr); /* reserved space */
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memset(&khdr, 0, sizeof(khdr));
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khdr.version = 1;
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list_for_each_entry_rcu(qe, &ima_measurements, later) {
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if (file.count < file.size) {
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khdr.count++;
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ima_measurements_show(&file, qe);
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} else {
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ret = -EINVAL;
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break;
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}
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}
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if (ret < 0)
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goto out;
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/*
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* fill in reserved space with some buffer details
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* (eg. version, buffer size, number of measurements)
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*/
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khdr.buffer_size = file.count;
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if (ima_canonical_fmt) {
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khdr.version = cpu_to_le16(khdr.version);
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khdr.count = cpu_to_le64(khdr.count);
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khdr.buffer_size = cpu_to_le64(khdr.buffer_size);
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}
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memcpy(file.buf, &khdr, sizeof(khdr));
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print_hex_dump(KERN_DEBUG, "ima dump: ", DUMP_PREFIX_NONE,
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16, 1, file.buf,
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file.count < 100 ? file.count : 100, true);
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*buffer_size = file.count;
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*buffer = file.buf;
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out:
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if (ret == -EINVAL)
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vfree(file.buf);
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return ret;
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}
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/*
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* Called during kexec_file_load so that IMA can add a segment to the kexec
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* image for the measurement list for the next kernel.
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*
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* This function assumes that kexec_mutex is held.
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*/
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void ima_add_kexec_buffer(struct kimage *image)
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{
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struct kexec_buf kbuf = { .image = image, .buf_align = PAGE_SIZE,
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.buf_min = 0, .buf_max = ULONG_MAX,
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.top_down = true };
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unsigned long binary_runtime_size;
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/* use more understandable variable names than defined in kbuf */
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void *kexec_buffer = NULL;
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size_t kexec_buffer_size;
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size_t kexec_segment_size;
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int ret;
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/*
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* Reserve an extra half page of memory for additional measurements
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* added during the kexec load.
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*/
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binary_runtime_size = ima_get_binary_runtime_size();
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if (binary_runtime_size >= ULONG_MAX - PAGE_SIZE)
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kexec_segment_size = ULONG_MAX;
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else
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kexec_segment_size = ALIGN(ima_get_binary_runtime_size() +
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PAGE_SIZE / 2, PAGE_SIZE);
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if ((kexec_segment_size == ULONG_MAX) ||
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((kexec_segment_size >> PAGE_SHIFT) > totalram_pages / 2)) {
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pr_err("Binary measurement list too large.\n");
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return;
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}
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ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
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kexec_segment_size);
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if (!kexec_buffer) {
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pr_err("Not enough memory for the kexec measurement buffer.\n");
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return;
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}
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kbuf.buffer = kexec_buffer;
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kbuf.bufsz = kexec_buffer_size;
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kbuf.memsz = kexec_segment_size;
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ret = kexec_add_buffer(&kbuf);
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if (ret) {
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pr_err("Error passing over kexec measurement buffer.\n");
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return;
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}
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ret = arch_ima_add_kexec_buffer(image, kbuf.mem, kexec_segment_size);
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if (ret) {
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pr_err("Error passing over kexec measurement buffer.\n");
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return;
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}
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pr_debug("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
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kbuf.mem);
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}
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#endif /* IMA_KEXEC */
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/*
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* Restore the measurement list from the previous kernel.
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*/
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void ima_load_kexec_buffer(void)
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{
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void *kexec_buffer = NULL;
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size_t kexec_buffer_size = 0;
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int rc;
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rc = ima_get_kexec_buffer(&kexec_buffer, &kexec_buffer_size);
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switch (rc) {
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case 0:
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rc = ima_restore_measurement_list(kexec_buffer_size,
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kexec_buffer);
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if (rc != 0)
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pr_err("Failed to restore the measurement list: %d\n",
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rc);
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ima_free_kexec_buffer();
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break;
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case -ENOTSUPP:
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pr_debug("Restoring the measurement list not supported\n");
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break;
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case -ENOENT:
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pr_debug("No measurement list to restore\n");
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break;
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default:
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pr_debug("Error restoring the measurement list: %d\n", rc);
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}
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}
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