cryptsetup/lib/utils.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * utils - miscellaneous device utilities for cryptsetup
 *
 * Copyright (C) 2004 Jana Saout <jana@saout.de>
 * Copyright (C) 2004-2007 Clemens Fruhwirth <clemens@endorphin.org>
 * Copyright (C) 2009-2024 Red Hat, Inc. All rights reserved.
 * Copyright (C) 2009-2024 Milan Broz
 */

#include <stdio.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/utsname.h>

#include "internal.h"

size_t crypt_getpagesize(void)
{
	long r = sysconf(_SC_PAGESIZE);
	return r <= 0 ? DEFAULT_MEM_ALIGNMENT : (size_t)r;
}

unsigned crypt_cpusonline(void)
{
	long r = sysconf(_SC_NPROCESSORS_ONLN);
	return r < 0 ? 1 : r;
}

uint64_t crypt_getphysmemory_kb(void)
{
	long pagesize, phys_pages;
	uint64_t phys_memory_kb, page_size_kb;

	pagesize = sysconf(_SC_PAGESIZE);
	phys_pages = sysconf(_SC_PHYS_PAGES);

	if (pagesize <= 0 || phys_pages <= 0)
		return 0;

	page_size_kb = pagesize / 1024;
	phys_memory_kb = page_size_kb * phys_pages;

	/* sanity check for overflow */
	if (phys_memory_kb / phys_pages != page_size_kb)
		return 0;

	/* coverity[return_overflow:FALSE] */
	return phys_memory_kb;
}

uint64_t crypt_getphysmemoryfree_kb(void)
{
	long pagesize, phys_pages;
	uint64_t phys_memoryfree_kb, page_size_kb;

	pagesize = sysconf(_SC_PAGESIZE);
	phys_pages = sysconf(_SC_AVPHYS_PAGES);

	if (pagesize <= 0 || phys_pages <= 0)
		return 0;

	page_size_kb = pagesize / 1024;
	phys_memoryfree_kb = page_size_kb * phys_pages;

	/* sanity check for overflow */
	if (phys_memoryfree_kb / phys_pages != page_size_kb)
		return 0;

	/* coverity[return_overflow:FALSE] */
	return phys_memoryfree_kb;
}

bool crypt_swapavailable(void)
{
	int fd;
	ssize_t size;
	char buf[4096], *p;
	uint64_t total;

	if ((fd = open("/proc/meminfo", O_RDONLY)) < 0)
		return true;

	size = read(fd, buf, sizeof(buf));
	close(fd);
	if (size < 1)
		return true;

	if (size < (ssize_t)sizeof(buf))
		buf[size] = 0;
	else
		buf[sizeof(buf) - 1] = 0;

	p = strstr(buf, "SwapTotal:");
	if (!p)
		return true;

	if (sscanf(p, "SwapTotal: %" PRIu64 " kB", &total) != 1)
		return true;

	return total > 0;
}

void crypt_process_priority(struct crypt_device *cd, int *priority, bool raise)
{
	int _priority, new_priority;

	if (raise) {
		_priority = getpriority(PRIO_PROCESS, 0);
		if (_priority < 0)
			_priority = 0;
		if (priority)
			*priority = _priority;

		/*
		 * Do not bother checking CAP_SYS_NICE as device activation
		 * requires CAP_SYSADMIN later anyway.
		 */
		if (getuid() || geteuid())
			new_priority = 0;
		else
			new_priority = -18;

		if (setpriority(PRIO_PROCESS, 0, new_priority))
			log_dbg(cd, "Cannot raise process priority.");
	} else {
		_priority = priority ? *priority : 0;
		if (setpriority(PRIO_PROCESS, 0, _priority))
			log_dbg(cd, "Cannot reset process priority.");
	}
}

/* Keyfile processing */

/*
 * A simple call to lseek(3) might not be possible for some inputs (e.g.
 * reading from a pipe), so this function instead reads of up to BUFSIZ bytes
 * at a time until the specified number of bytes. It returns -1 on read error
 * or when it reaches EOF before the requested number of bytes have been
 * discarded.
 */
static int keyfile_seek(int fd, uint64_t bytes)
{
	char tmp[BUFSIZ];
	size_t next_read;
	ssize_t bytes_r;
	off_t r;

	r = lseek(fd, bytes, SEEK_CUR);
	if (r > 0)
		return 0;
	if (r < 0 && errno != ESPIPE)
		return -1;

	while (bytes > 0) {
		/* figure out how much to read */
		next_read = bytes > sizeof(tmp) ? sizeof(tmp) : (size_t)bytes;

		bytes_r = read(fd, tmp, next_read);
		if (bytes_r < 0) {
			if (errno == EINTR)
				continue;

			crypt_safe_memzero(tmp, sizeof(tmp));
			/* read error */
			return -1;
		}

		if (bytes_r == 0)
			/* EOF */
			break;

		bytes -= bytes_r;
	}

	crypt_safe_memzero(tmp, sizeof(tmp));
	return bytes == 0 ? 0 : -1;
}

int crypt_keyfile_device_read(struct crypt_device *cd,  const char *keyfile,
			      char **key, size_t *key_size_read,
			      uint64_t keyfile_offset, size_t key_size,
			      uint32_t flags)
{
	int fd, regular_file, char_to_read = 0, char_read = 0, unlimited_read = 0;
	int r = -EINVAL, newline;
	char *pass = NULL;
	size_t buflen, i;
	uint64_t file_read_size;
	struct stat st;
	bool close_fd = false;

	if (!key || !key_size_read)
		return -EINVAL;

	*key = NULL;
	*key_size_read = 0;

	if (keyfile) {
		fd = open(keyfile, O_RDONLY);
		if (fd < 0) {
			log_err(cd, _("Failed to open key file."));
			return -EINVAL;
		}
		close_fd = true;
	} else
		fd = STDIN_FILENO;

	if (isatty(fd)) {
		log_err(cd, _("Cannot read keyfile from a terminal."));
		goto out;
	}

	/* If not requested otherwise, we limit input to prevent memory exhaustion */
	if (key_size == 0) {
		key_size = DEFAULT_KEYFILE_SIZE_MAXKB * 1024 + 1;
		unlimited_read = 1;
		/* use 4k for buffer (page divisor but avoid huge pages) */
		buflen = 4096 - 16; /* sizeof(struct safe_allocation); */
	} else
		buflen = key_size;

	regular_file = 0;
	if (keyfile) {
		if (stat(keyfile, &st) < 0) {
			log_err(cd, _("Failed to stat key file."));
			goto out;
		}
		if (S_ISREG(st.st_mode)) {
			regular_file = 1;
			file_read_size = (uint64_t)st.st_size;

			if (keyfile_offset > file_read_size) {
				log_err(cd, _("Cannot seek to requested keyfile offset."));
				goto out;
			}
			file_read_size -= keyfile_offset;

			/* known keyfile size, alloc it in one step */
			if (file_read_size >= (uint64_t)key_size)
				buflen = key_size;
			else if (file_read_size)
				buflen = file_read_size;
		}
	}

	pass = crypt_safe_alloc(buflen);
	if (!pass) {
		log_err(cd, _("Out of memory while reading passphrase."));
		goto out;
	}

	/* Discard keyfile_offset bytes on input */
	if (keyfile_offset && keyfile_seek(fd, keyfile_offset) < 0) {
		log_err(cd, _("Cannot seek to requested keyfile offset."));
		goto out;
	}

	for (i = 0, newline = 0; i < key_size; i += char_read) {
		if (i == buflen) {
			buflen += 4096;
			pass = crypt_safe_realloc(pass, buflen);
			if (!pass) {
				log_err(cd, _("Out of memory while reading passphrase."));
				r = -ENOMEM;
				goto out;
			}
		}

		if (flags & CRYPT_KEYFILE_STOP_EOL) {
			/* If we should stop on newline, we must read the input
			 * one character at the time. Otherwise we might end up
			 * having read some bytes after the newline, which we
			 * promised not to do.
			 */
			char_to_read = 1;
		} else {
			/* char_to_read = min(key_size - i, buflen - i) */
			char_to_read = key_size < buflen ?
				key_size - i : buflen - i;
		}
		char_read = read_buffer(fd, &pass[i], char_to_read);
		if (char_read < 0) {
			log_err(cd, _("Error reading passphrase."));
			r = -EPIPE;
			goto out;
		}

		if (char_read == 0)
			break;
		/* Stop on newline only if not requested read from keyfile */
		if ((flags & CRYPT_KEYFILE_STOP_EOL) && pass[i] == '\n') {
			newline = 1;
			pass[i] = '\0';
			break;
		}
	}

	/* Fail if piped input dies reading nothing */
	if (!i && !regular_file && !newline) {
		log_err(cd, _("Nothing to read on input."));
		r = -EPIPE;
		goto out;
	}

	/* Fail if we exceeded internal default (no specified size) */
	if (unlimited_read && i == key_size) {
		log_err(cd, _("Maximum keyfile size exceeded."));
		goto out;
	}

	if (!unlimited_read && i != key_size) {
		log_err(cd, _("Cannot read requested amount of data."));
		goto out;
	}

	*key = pass;
	*key_size_read = i;
	r = 0;
out:
	if (close_fd)
		close(fd);

	if (r)
		crypt_safe_free(pass);
	return r;
}

int crypt_keyfile_read(struct crypt_device *cd,  const char *keyfile,
		       char **key, size_t *key_size_read,
		       size_t keyfile_offset, size_t keyfile_size_max,
		       uint32_t flags)
{
	return crypt_keyfile_device_read(cd, keyfile, key, key_size_read,
					 keyfile_offset, keyfile_size_max, flags);
}

int kernel_version(uint64_t *kversion)
{
	struct utsname uts;
	uint16_t maj, min, patch, rel;
	int r = -EINVAL;

	if (uname(&uts) < 0)
		return r;

	if (sscanf(uts.release, "%" SCNu16  ".%" SCNu16 ".%" SCNu16 "-%" SCNu16,
		   &maj, &min, &patch, &rel) == 4)
		r = 0;
	else if (sscanf(uts.release,  "%" SCNu16 ".%" SCNu16 ".%" SCNu16,
			&maj, &min, &patch) == 3) {
		rel = 0;
		r = 0;
	}

	if (!r)
		*kversion = compact_version(maj, min, patch, rel);

	return r;
}

bool crypt_string_in(const char *str, char **list, size_t list_size)
{
	size_t i;

	for (i = 0; *list && i < list_size; i++, list++)
		if (!strcmp(str, *list))
			return true;

	return false;
}

/* compare two strings (allows NULL values) */
int crypt_strcmp(const char *a, const char *b)
{
	if (!a && !b)
		return 0;
	else if (!a || !b)
		return 1;
	return strcmp(a, b);
}