secmem.c
No OneTemporary
Actions

Size

15 KB

Subscribers

None

secmem.c
View Options

	/* secmem.c - memory allocation from a secure heap
	* Copyright (C) 1998, 1999, 2000, 2001, 2002,
	* 2003, 2007 Free Software Foundation, Inc.
	*
	* This file is part of Libgcrypt.
	*
	* Libgcrypt is free software; you can redistribute it and/or modify
	* it under the terms of the GNU Lesser general Public License as
	* published by the Free Software Foundation; either version 2.1 of
	* the License, or (at your option) any later version.
	*
	* Libgcrypt is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with this program; if not, see <http://www.gnu.org/licenses/>.
	*/

	#include <config.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <errno.h>
	#include <stdarg.h>
	#include <unistd.h>
	#include <stddef.h>

	#if defined(HAVE_MLOCK) \|\| defined(HAVE_MMAP)
	#include <sys/mman.h>
	#include <sys/types.h>
	#include <fcntl.h>
	#ifdef USE_CAPABILITIES
	#include <sys/capability.h>
	#endif
	#endif

	#include "ath.h"
	#include "g10lib.h"
	#include "secmem.h"

	#if defined (MAP_ANON) && ! defined (MAP_ANONYMOUS)
	#define MAP_ANONYMOUS MAP_ANON
	#endif

	#define MINIMUM_POOL_SIZE 16384
	#define STANDARD_POOL_SIZE 32768
	#define DEFAULT_PAGE_SIZE 4096

	typedef struct memblock
	{
	unsigned size; /* Size of the memory available to the
	user. */
	int flags; /* See below. */
	PROPERLY_ALIGNED_TYPE aligned;
	} memblock_t;

	/* This flag specifies that the memory block is in use. */
	#define MB_FLAG_ACTIVE (1 << 0)

	/* The pool of secure memory. */
	static void *pool;

	/* Size of POOL in bytes. */
	static size_t pool_size;

	/* True, if the memory pool is ready for use. May be checked in an
	atexit function. */
	static volatile int pool_okay;

	/* True, if the memory pool is mmapped. */
	static volatile int pool_is_mmapped;

	/* FIXME? */
	static int disable_secmem;
	static int show_warning;
	static int not_locked;
	static int no_warning;
	static int suspend_warning;

	/* Stats. */
	static unsigned int cur_alloced, cur_blocks;

	/* Lock protecting accesses to the memory pool. */
	static ath_mutex_t secmem_lock;

	/* Convenient macros. */
	#define SECMEM_LOCK ath_mutex_lock (&secmem_lock)
	#define SECMEM_UNLOCK ath_mutex_unlock (&secmem_lock)

	/* The size of the memblock structure; this does not include the
	memory that is available to the user. */
	#define BLOCK_HEAD_SIZE \
	offsetof (memblock_t, aligned)

	/* Convert an address into the according memory block structure. */
	#define ADDR_TO_BLOCK(addr) \
	(memblock_t ) ((char ) addr - BLOCK_HEAD_SIZE)

	/* Check whether P points into the pool. */
	static int
	ptr_into_pool_p (const void *p)
	{
	/* We need to convert pointers to addresses. This is required by
	C-99 6.5.8 to avoid undefined behaviour. Using size_t is at
	least only implementation defined. See also
	http://lists.gnupg.org/pipermail/gcrypt-devel/2007-February/001102.html
	*/
	size_t p_addr = (size_t)p;
	size_t pool_addr = (size_t)pool;

	return p_addr >= pool_addr && p_addr < pool_addr+pool_size;
	}

	/* Update the stats. */
	static void
	stats_update (size_t add, size_t sub)
	{
	if (add)
	{
	cur_alloced += add;
	cur_blocks++;
	}
	if (sub)
	{
	cur_alloced -= sub;
	cur_blocks--;
	}
	}

	/* Return the block following MB or NULL, if MB is the last block. */
	static memblock_t *
	mb_get_next (memblock_t *mb)
	{
	memblock_t *mb_next;

	mb_next = (memblock_t ) ((char ) mb + BLOCK_HEAD_SIZE + mb->size);

	if (! ptr_into_pool_p (mb_next))
	mb_next = NULL;

	return mb_next;
	}

	/* Return the block preceding MB or NULL, if MB is the first
	block. */
	static memblock_t *
	mb_get_prev (memblock_t *mb)
	{
	memblock_t mb_prev, mb_next;

	if (mb == pool)
	mb_prev = NULL;
	else
	{
	mb_prev = (memblock_t *) pool;
	while (1)
	{
	mb_next = mb_get_next (mb_prev);
	if (mb_next == mb)
	break;
	else
	mb_prev = mb_next;
	}
	}

	return mb_prev;
	}

	/* If the preceding block of MB and/or the following block of MB
	exist and are not active, merge them to form a bigger block. */
	static void
	mb_merge (memblock_t *mb)
	{
	memblock_t mb_prev, mb_next;

	mb_prev = mb_get_prev (mb);
	mb_next = mb_get_next (mb);

	if (mb_prev && (! (mb_prev->flags & MB_FLAG_ACTIVE)))
	{
	mb_prev->size += BLOCK_HEAD_SIZE + mb->size;
	mb = mb_prev;
	}
	if (mb_next && (! (mb_next->flags & MB_FLAG_ACTIVE)))
	mb->size += BLOCK_HEAD_SIZE + mb_next->size;
	}

	/* Return a new block, which can hold SIZE bytes. */
	static memblock_t *
	mb_get_new (memblock_t *block, size_t size)
	{
	memblock_t mb, mb_split;

	for (mb = block; ptr_into_pool_p (mb); mb = mb_get_next (mb))
	if (! (mb->flags & MB_FLAG_ACTIVE) && mb->size >= size)
	{
	/* Found a free block. */
	mb->flags \|= MB_FLAG_ACTIVE;

	if (mb->size - size > BLOCK_HEAD_SIZE)
	{
	/* Split block. */

	mb_split = (memblock_t ) (((char ) mb) + BLOCK_HEAD_SIZE + size);
	mb_split->size = mb->size - size - BLOCK_HEAD_SIZE;
	mb_split->flags = 0;

	mb->size = size;

	mb_merge (mb_split);

	}

	break;
	}

	if (! ptr_into_pool_p (mb))
	{
	gpg_err_set_errno (ENOMEM);
	mb = NULL;
	}

	return mb;
	}

	/* Print a warning message. */
	static void
	print_warn (void)
	{
	if (!no_warning)
	log_info (_("Warning: using insecure memory!\n"));
	}

	/* Lock the memory pages into core and drop privileges. */
	static void
	lock_pool (void *p, size_t n)
	{
	#if defined(USE_CAPABILITIES) && defined(HAVE_MLOCK)
	int err;

	cap_set_proc (cap_from_text ("cap_ipc_lock+ep"));
	err = mlock (p, n);
	if (err && errno)
	err = errno;
	cap_set_proc (cap_from_text ("cap_ipc_lock+p"));

	if (err)
	{
	if (errno != EPERM
	#ifdef EAGAIN /* OpenBSD returns this */
	&& errno != EAGAIN
	#endif
	#ifdef ENOSYS /* Some SCOs return this (function not implemented) */
	&& errno != ENOSYS
	#endif
	#ifdef ENOMEM /* Linux might return this. */
	&& errno != ENOMEM
	#endif
	)
	log_error ("can't lock memory: %s\n", strerror (err));
	show_warning = 1;
	not_locked = 1;
	}

	#elif defined(HAVE_MLOCK)
	uid_t uid;
	int err;

	uid = getuid ();

	#ifdef HAVE_BROKEN_MLOCK
	/* Under HP/UX mlock segfaults if called by non-root. Note, we have
	noch checked whether mlock does really work under AIX where we
	also detected a broken nlock. Note further, that using plock ()
	is not a good idea under AIX. */
	if (uid)
	{
	errno = EPERM;
	err = errno;
	}
	else
	{
	err = mlock (p, n);
	if (err && errno)
	err = errno;
	}
	#else /* !HAVE_BROKEN_MLOCK */
	err = mlock (p, n);
	if (err && errno)
	err = errno;
	#endif /* !HAVE_BROKEN_MLOCK */

	if (uid && ! geteuid ())
	{
	/* check that we really dropped the privs.
	* Note: setuid(0) should always fail */
	if (setuid (uid) \|\| getuid () != geteuid () \|\| !setuid (0))
	log_fatal ("failed to reset uid: %s\n", strerror (errno));
	}

	if (err)
	{
	if (errno != EPERM
	#ifdef EAGAIN /* OpenBSD returns this. */
	&& errno != EAGAIN
	#endif
	#ifdef ENOSYS /* Some SCOs return this (function not implemented). */
	&& errno != ENOSYS
	#endif
	#ifdef ENOMEM /* Linux might return this. */
	&& errno != ENOMEM
	#endif
	)
	log_error ("can't lock memory: %s\n", strerror (err));
	show_warning = 1;
	not_locked = 1;
	}

	#elif defined ( __QNX__ )
	/* QNX does not page at all, so the whole secure memory stuff does
	* not make much sense. However it is still of use because it
	* wipes out the memory on a free().
	* Therefore it is sufficient to suppress the warning. */
	(void)p;
	(void)n;
	#elif defined (HAVE_DOSISH_SYSTEM) \|\| defined (__CYGWIN__)
	/* It does not make sense to print such a warning, given the fact that
	* this whole Windows !@#$% and their user base are inherently insecure. */
	(void)p;
	(void)n;
	#elif defined (__riscos__)
	/* No virtual memory on RISC OS, so no pages are swapped to disc,
	* besides we don't have mmap, so we don't use it! ;-)
	* But don't complain, as explained above. */
	(void)p;
	(void)n;
	#else
	(void)p;
	(void)n;
	log_info ("Please note that you don't have secure memory on this system\n");
	#endif
	}

	/* Initialize POOL. */
	static void
	init_pool (size_t n)
	{
	size_t pgsize;
	long int pgsize_val;
	memblock_t *mb;

	pool_size = n;

	if (disable_secmem)
	log_bug ("secure memory is disabled");

	#if defined(HAVE_SYSCONF) && defined(_SC_PAGESIZE)
	pgsize_val = sysconf (_SC_PAGESIZE);
	#elif defined(HAVE_GETPAGESIZE)
	pgsize_val = getpagesize ();
	#else
	pgsize_val = -1;
	#endif
	pgsize = (pgsize_val != -1 && pgsize_val > 0)? pgsize_val:DEFAULT_PAGE_SIZE;


	#if HAVE_MMAP
	pool_size = (pool_size + pgsize - 1) & ~(pgsize - 1);
	#ifdef MAP_ANONYMOUS
	pool = mmap (0, pool_size, PROT_READ \| PROT_WRITE,
	MAP_PRIVATE \| MAP_ANONYMOUS, -1, 0);
	#else /* map /dev/zero instead */
	{
	int fd;

	fd = open ("/dev/zero", O_RDWR);
	if (fd == -1)
	{
	log_error ("can't open /dev/zero: %s\n", strerror (errno));
	pool = (void *) -1;
	}
	else
	{
	pool = mmap (0, pool_size, PROT_READ \| PROT_WRITE, MAP_PRIVATE, fd, 0);
	close (fd);
	}
	}
	#endif
	if (pool == (void *) -1)
	log_info ("can't mmap pool of %u bytes: %s - using malloc\n",
	(unsigned) pool_size, strerror (errno));
	else
	{
	pool_is_mmapped = 1;
	pool_okay = 1;
	}

	#endif
	if (!pool_okay)
	{
	pool = malloc (pool_size);
	if (!pool)
	log_fatal ("can't allocate memory pool of %u bytes\n",
	(unsigned) pool_size);
	else
	pool_okay = 1;
	}

	/* Initialize first memory block. */
	mb = (memblock_t *) pool;
	mb->size = pool_size;
	mb->flags = 0;
	}

	void
	_gcry_secmem_set_flags (unsigned flags)
	{
	int was_susp;

	SECMEM_LOCK;

	was_susp = suspend_warning;
	no_warning = flags & GCRY_SECMEM_FLAG_NO_WARNING;
	suspend_warning = flags & GCRY_SECMEM_FLAG_SUSPEND_WARNING;

	/* and now issue the warning if it is not longer suspended */
	if (was_susp && !suspend_warning && show_warning)
	{
	show_warning = 0;
	print_warn ();
	}

	SECMEM_UNLOCK;
	}

	unsigned int
	_gcry_secmem_get_flags (void)
	{
	unsigned flags;

	SECMEM_LOCK;

	flags = no_warning ? GCRY_SECMEM_FLAG_NO_WARNING : 0;
	flags \|= suspend_warning ? GCRY_SECMEM_FLAG_SUSPEND_WARNING : 0;
	flags \|= not_locked ? GCRY_SECMEM_FLAG_NOT_LOCKED : 0;

	SECMEM_UNLOCK;

	return flags;
	}


	/* See _gcry_secmem_init. This function is expected to be called with
	the secmem lock held. */
	static void
	secmem_init (size_t n)
	{
	if (!n)
	{
	#ifdef USE_CAPABILITIES
	/* drop all capabilities */
	cap_set_proc (cap_from_text ("all-eip"));

	#elif !defined(HAVE_DOSISH_SYSTEM)
	uid_t uid;

	disable_secmem = 1;
	uid = getuid ();
	if (uid != geteuid ())
	{
	if (setuid (uid) \|\| getuid () != geteuid () \|\| !setuid (0))
	log_fatal ("failed to drop setuid\n");
	}
	#endif
	}
	else
	{
	if (n < MINIMUM_POOL_SIZE)
	n = MINIMUM_POOL_SIZE;
	if (! pool_okay)
	{
	init_pool (n);
	lock_pool (pool, n);
	}
	else
	log_error ("Oops, secure memory pool already initialized\n");
	}
	}



	/* Initialize the secure memory system. If running with the necessary
	privileges, the secure memory pool will be locked into the core in
	order to prevent page-outs of the data. Furthermore allocated
	secure memory will be wiped out when released. */
	void
	_gcry_secmem_init (size_t n)
	{
	SECMEM_LOCK;

	secmem_init (n);

	SECMEM_UNLOCK;
	}


	gcry_err_code_t
	_gcry_secmem_module_init ()
	{
	int err;

	err = ath_mutex_init (&secmem_lock);
	if (err)
	log_fatal ("could not allocate secmem lock\n");

	return 0;
	}


	static void *
	_gcry_secmem_malloc_internal (size_t size)
	{
	memblock_t *mb;

	if (!pool_okay)
	{
	/* Try to initialize the pool if the user forgot about it. */
	secmem_init (STANDARD_POOL_SIZE);
	if (!pool_okay)
	{
	log_info (_("operation is not possible without "
	"initialized secure memory\n"));
	gpg_err_set_errno (ENOMEM);
	return NULL;
	}
	}
	if (not_locked && fips_mode ())
	{
	log_info (_("secure memory pool is not locked while in FIPS mode\n"));
	gpg_err_set_errno (ENOMEM);
	return NULL;
	}
	if (show_warning && !suspend_warning)
	{
	show_warning = 0;
	print_warn ();
	}

	/* Blocks are always a multiple of 32. */
	size = ((size + 31) / 32) * 32;

	mb = mb_get_new ((memblock_t *) pool, size);
	if (mb)
	stats_update (size, 0);

	return mb ? &mb->aligned.c : NULL;
	}

	void *
	_gcry_secmem_malloc (size_t size)
	{
	void *p;

	SECMEM_LOCK;
	p = _gcry_secmem_malloc_internal (size);
	SECMEM_UNLOCK;

	return p;
	}

	static void
	_gcry_secmem_free_internal (void *a)
	{
	memblock_t *mb;
	int size;

	if (!a)
	return;

	mb = ADDR_TO_BLOCK (a);
	size = mb->size;

	/* This does not make much sense: probably this memory is held in the
	* cache. We do it anyway: */
	#define MB_WIPE_OUT(byte) \
	wipememory2 ((memblock_t ) ((char ) mb + BLOCK_HEAD_SIZE), (byte), size);

	MB_WIPE_OUT (0xff);
	MB_WIPE_OUT (0xaa);
	MB_WIPE_OUT (0x55);
	MB_WIPE_OUT (0x00);

	stats_update (0, size);

	mb->flags &= ~MB_FLAG_ACTIVE;

	/* Update stats. */

	mb_merge (mb);
	}

	/* Wipe out and release memory. */
	void
	_gcry_secmem_free (void *a)
	{
	SECMEM_LOCK;
	_gcry_secmem_free_internal (a);
	SECMEM_UNLOCK;
	}

	/* Realloc memory. */
	void *
	_gcry_secmem_realloc (void *p, size_t newsize)
	{
	memblock_t *mb;
	size_t size;
	void *a;

	SECMEM_LOCK;

	mb = (memblock_t ) ((char ) p - ((size_t) &((memblock_t *) 0)->aligned.c));
	size = mb->size;
	if (newsize < size)
	{
	/* It is easier to not shrink the memory. */
	a = p;
	}
	else
	{
	a = _gcry_secmem_malloc_internal (newsize);
	if (a)
	{
	memcpy (a, p, size);
	memset ((char *) a + size, 0, newsize - size);
	_gcry_secmem_free_internal (p);
	}
	}

	SECMEM_UNLOCK;

	return a;
	}


	/* Return true if P points into the secure memory area. */
	int
	_gcry_private_is_secure (const void *p)
	{
	return pool_okay && ptr_into_pool_p (p);
	}


	/****************
	* Warning: This code might be called by an interrupt handler
	* and frankly, there should really be such a handler,
	* to make sure that the memory is wiped out.
	* We hope that the OS wipes out mlocked memory after
	* receiving a SIGKILL - it really should do so, otherwise
	* there is no chance to get the secure memory cleaned.
	*/
	void
	_gcry_secmem_term ()
	{
	if (!pool_okay)
	return;

	wipememory2 (pool, 0xff, pool_size);
	wipememory2 (pool, 0xaa, pool_size);
	wipememory2 (pool, 0x55, pool_size);
	wipememory2 (pool, 0x00, pool_size);
	#if HAVE_MMAP
	if (pool_is_mmapped)
	munmap (pool, pool_size);
	#endif
	pool = NULL;
	pool_okay = 0;
	pool_size = 0;
	not_locked = 0;
	}


	void
	_gcry_secmem_dump_stats ()
	{
	#if 1
	SECMEM_LOCK;

	if (pool_okay)
	log_info ("secmem usage: %u/%lu bytes in %u blocks\n",
	cur_alloced, (unsigned long)pool_size, cur_blocks);
	SECMEM_UNLOCK;
	#else
	memblock_t *mb;
	int i;

	SECMEM_LOCK;

	for (i = 0, mb = (memblock_t *) pool;
	ptr_into_pool_p (mb);
	mb = mb_get_next (mb), i++)
	log_info ("SECMEM: [%s] block: %i; size: %i\n",
	(mb->flags & MB_FLAG_ACTIVE) ? "used" : "free",
	i,
	mb->size);
	SECMEM_UNLOCK;
	#endif
	}

File Metadata

Mime Type: text/x-c
Expires: Fri, Mar 14, 4:41 AM (1 d, 16 h)
Storage Engine: local-disk
Storage Format: Raw Data
Storage Handle: af/3a/bfa472561d892dbfada4ea2a23ee

secmem.cNo OneTemporaryActions

secmem.cView Options

File Metadata

Event Timeline

secmem.c
No OneTemporary
Actions

secmem.c
View Options