modutils/modutils.c - busybox - Git at Google

 /*
  * Common modutils related functions for busybox
  *
  * Copyright (C) 2008 by Timo Teras <timo.teras@iki.fi>
  *
  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
 #include "modutils.h"

 #include <sys/syscall.h>

 #define init_module(mod, len, opts) syscall(__NR_init_module, mod, len, opts)
 #if defined(__NR_finit_module)
 # define finit_module(fd, uargs, flags) syscall(__NR_finit_module, fd, uargs, flags)
 #endif
 #define delete_module(mod, flags) syscall(__NR_delete_module, mod, flags)

 static module_entry *helper_get_module(module_db *db, const char *module, int create)
 {
 	char modname[MODULE_NAME_LEN];
 	struct module_entry *e;
 	unsigned i, hash;

 	filename2modname(module, modname);

 	hash = 0;
 	for (i = 0; modname[i]; i++)
 		hash = ((hash << 5) + hash) + modname[i];
 	hash %= MODULE_HASH_SIZE;

 	for (e = db->buckets[hash]; e; e = e->next)
 		if (strcmp(e->modname, modname) == 0)
 			return e;
 	if (!create)
 		return NULL;

 	e = xzalloc(sizeof(*e));
 	e->modname = xstrdup(modname);
 	e->next = db->buckets[hash];
 	db->buckets[hash] = e;
 	IF_DEPMOD(e->dnext = e->dprev = e;)

 	return e;
 }
 module_entry* FAST_FUNC moddb_get(module_db *db, const char *module)
 {
 	return helper_get_module(db, module, 0);
 }
 module_entry* FAST_FUNC moddb_get_or_create(module_db *db, const char *module)
 {
 	return helper_get_module(db, module, 1);
 }

 void FAST_FUNC moddb_free(module_db *db)
 {
 	module_entry *e, *n;
 	unsigned i;

 	for (i = 0; i < MODULE_HASH_SIZE; i++) {
 		for (e = db->buckets[i]; e; e = n) {
 			n = e->next;
 			free(e->name);
 			free(e->modname);
 			free(e);
 		}
 	}
 }

 void FAST_FUNC replace(char *s, char what, char with)
 {
 	while (*s) {
 		if (what == *s)
 			*s = with;
 		++s;
 	}
 }

 int FAST_FUNC string_to_llist(char *string, llist_t **llist, const char *delim)
 {
 	char *tok;
 	int len = 0;

 	while ((tok = strsep(&string, delim)) != NULL) {
 		if (tok[0] == '\0')
 			continue;
 		llist_add_to_end(llist, xstrdup(tok));
 		len += strlen(tok);
 	}
 	return len;
 }

 char* FAST_FUNC filename2modname(const char *filename, char *modname)
 {
 	char local_modname[MODULE_NAME_LEN];
 	int i;
 	const char *from;

 	if (filename == NULL)
 		return NULL;
 	if (modname == NULL)
 		modname = local_modname;
 	// Disabled since otherwise "modprobe dir/name" would work
 	// as if it is "modprobe name". It is unclear why
 	// 'basenamization' was here in the first place.
 	//from = bb_get_last_path_component_nostrip(filename);
 	from = filename;
 	for (i = 0; i < (MODULE_NAME_LEN-1) && from[i] != '\0' && from[i] != '.'; i++)
 		modname[i] = (from[i] == '-') ? '_' : from[i];
 	modname[i] = '\0';

 	if (modname == local_modname)
 		return xstrdup(modname);

 	return modname;
 }

 #if ENABLE_FEATURE_CMDLINE_MODULE_OPTIONS
 char* FAST_FUNC parse_cmdline_module_options(char **argv, int quote_spaces)
 {
 	char *options;
 	int optlen;

 	options = xzalloc(1);
 	optlen = 0;
 	while (*++argv) {
 		const char *fmt;
 		const char *var;
 		const char *val;

 		var = *argv;
 		options = xrealloc(options, optlen + 2 + strlen(var) + 2);
 		fmt = "%.*s%s ";
 		val = strchrnul(var, '=');
 		if (quote_spaces) {
 			/*
 			 * modprobe (module-init-tools version 3.11.1) compat:
 			 * quote only value:
 			 * var="val with spaces", not "var=val with spaces"
 			 * (note: var *name* is not checked for spaces!)
 			 */
 			if (*val) { /* has var=val format. skip '=' */
 				val++;
 				if (strchr(val, ' '))
 					fmt = "%.*s\"%s\" ";
 			}
 		}
 		optlen += sprintf(options + optlen, fmt, (int)(val - var), var, val);
 	}
 	/* Remove trailing space. Disabled */
 	/* if (optlen != 0) options[optlen-1] = '\0'; */
 	return options;
 }
 #endif

 #if ENABLE_FEATURE_INSMOD_TRY_MMAP
 void* FAST_FUNC try_to_mmap_module(const char *filename, size_t *image_size_p)
 {
 	/* We have user reports of failure to load 3MB module
 	 * on a 16MB RAM machine. Apparently even a transient
 	 * memory spike to 6MB during module load
 	 * is too big for that system. */
 	void *image;
 	struct stat st;
 	int fd;

 	fd = xopen(filename, O_RDONLY);
 	fstat(fd, &st);
 	image = NULL;
 	/* st.st_size is off_t, we can't just pass it to mmap */
 	if (st.st_size <= *image_size_p) {
 		size_t image_size = st.st_size;
 		image = mmap(NULL, image_size, PROT_READ, MAP_PRIVATE, fd, 0);
 		if (image == MAP_FAILED) {
 			image = NULL;
 		} else if (*(uint32_t*)image != SWAP_BE32(0x7f454C46)) {
 			/* No ELF signature. Compressed module? */
 			munmap(image, image_size);
 			image = NULL;
 		} else {
 			/* Success. Report the size */
 			*image_size_p = image_size;
 		}
 	}
 	close(fd);
 	return image;
 }
 #endif

 /* Return:
  * 0 on success,
  * -errno on open/read error,
  * errno on init_module() error
  */
 int FAST_FUNC bb_init_module(const char *filename, const char *options)
 {
 	size_t image_size;
 	char *image;
 	int rc;
 	bool mmaped;

 	if (!options)
 		options = "";

 //TODO: audit bb_init_module_24 to match error code convention
 #if ENABLE_FEATURE_2_4_MODULES
 	if (get_linux_version_code() < KERNEL_VERSION(2,6,0))
 		return bb_init_module_24(filename, options);
 #endif

 	/*
 	 * First we try finit_module if available.  Some kernels are configured
 	 * to only allow loading of modules off of secure storage (like a read-
 	 * only rootfs) which needs the finit_module call.  If it fails, we fall
 	 * back to normal module loading to support compressed modules.
 	 */
 # ifdef __NR_finit_module
 	{
 		int fd = open(filename, O_RDONLY | O_CLOEXEC);
 		if (fd >= 0) {
 			rc = finit_module(fd, options, 0) != 0;
 			close(fd);
 			if (rc == 0)
 				return rc;
 		}
 	}
 # endif

 	image_size = INT_MAX - 4095;
 	mmaped = 0;
 	image = try_to_mmap_module(filename, &image_size);
 	if (image) {
 		mmaped = 1;
 	} else {
 		errno = ENOMEM; /* may be changed by e.g. open errors below */
 		image = xmalloc_open_zipped_read_close(filename, &image_size);
 		if (!image)
 			return -errno;
 	}

 	errno = 0;
 	init_module(image, image_size, options);
 	rc = errno;
 	if (mmaped)
 		munmap(image, image_size);
 	else
 		free(image);
 	return rc;
 }

 int FAST_FUNC bb_delete_module(const char *module, unsigned int flags)
 {
 	errno = 0;
 	delete_module(module, flags);
 	return errno;
 }

 /* Note: not suitable for delete_module() errnos.
  * For them, probably only EWOULDBLOCK needs explaining:
  * "Other modules depend on us". So far we don't do such
  * translation and don't use moderror() for removal errors.
  */
 const char* FAST_FUNC moderror(int err)
 {
 	switch (err) {
 	case -1: /* btw: it's -EPERM */
 		return "no such module";
 	case ENOEXEC:
 		return "invalid module format";
 	case ENOENT:
 		return "unknown symbol in module, or unknown parameter";
 	case ESRCH:
 		return "module has wrong symbol version";
 	case ENOSYS:
 		return "kernel does not support requested operation";
 	}
 	if (err < 0) /* should always be */
 		err = -err;
 	return strerror(err);
 }
	/*
	* Common modutils related functions for busybox
	*
	* Copyright (C) 2008 by Timo Teras <timo.teras@iki.fi>
	*
	* Licensed under GPLv2 or later, see file LICENSE in this source tree.
	*/
	#include "modutils.h"

	#include <sys/syscall.h>

	#define init_module(mod, len, opts) syscall(__NR_init_module, mod, len, opts)
	#if defined(__NR_finit_module)
	# define finit_module(fd, uargs, flags) syscall(__NR_finit_module, fd, uargs, flags)
	#endif
	#define delete_module(mod, flags) syscall(__NR_delete_module, mod, flags)

	static module_entry helper_get_module(module_db db, const char *module, int create)
	{
	char modname[MODULE_NAME_LEN];
	struct module_entry *e;
	unsigned i, hash;

	filename2modname(module, modname);

	hash = 0;
	for (i = 0; modname[i]; i++)
	hash = ((hash << 5) + hash) + modname[i];
	hash %= MODULE_HASH_SIZE;

	for (e = db->buckets[hash]; e; e = e->next)
	if (strcmp(e->modname, modname) == 0)
	return e;
	if (!create)
	return NULL;

	e = xzalloc(sizeof(*e));
	e->modname = xstrdup(modname);
	e->next = db->buckets[hash];
	db->buckets[hash] = e;
	IF_DEPMOD(e->dnext = e->dprev = e;)

	return e;
	}
	module_entry* FAST_FUNC moddb_get(module_db db, const char module)
	{
	return helper_get_module(db, module, 0);
	}
	module_entry* FAST_FUNC moddb_get_or_create(module_db db, const char module)
	{
	return helper_get_module(db, module, 1);
	}

	void FAST_FUNC moddb_free(module_db *db)
	{
	module_entry e, n;
	unsigned i;

	for (i = 0; i < MODULE_HASH_SIZE; i++) {
	for (e = db->buckets[i]; e; e = n) {
	n = e->next;
	free(e->name);
	free(e->modname);
	free(e);
	}
	}
	}

	void FAST_FUNC replace(char *s, char what, char with)
	{
	while (*s) {
	if (what == *s)
	*s = with;
	++s;
	}
	}

	int FAST_FUNC string_to_llist(char string, llist_t llist, const char delim)
	{
	char *tok;
	int len = 0;

	while ((tok = strsep(&string, delim)) != NULL) {
	if (tok[0] == '\0')
	continue;
	llist_add_to_end(llist, xstrdup(tok));
	len += strlen(tok);
	}
	return len;
	}

	char* FAST_FUNC filename2modname(const char filename, char modname)
	{
	char local_modname[MODULE_NAME_LEN];
	int i;
	const char *from;

	if (filename == NULL)
	return NULL;
	if (modname == NULL)
	modname = local_modname;
	// Disabled since otherwise "modprobe dir/name" would work
	// as if it is "modprobe name". It is unclear why
	// 'basenamization' was here in the first place.
	//from = bb_get_last_path_component_nostrip(filename);
	from = filename;
	for (i = 0; i < (MODULE_NAME_LEN-1) && from[i] != '\0' && from[i] != '.'; i++)
	modname[i] = (from[i] == '-') ? '_' : from[i];
	modname[i] = '\0';

	if (modname == local_modname)
	return xstrdup(modname);

	return modname;
	}

	#if ENABLE_FEATURE_CMDLINE_MODULE_OPTIONS
	char* FAST_FUNC parse_cmdline_module_options(char **argv, int quote_spaces)
	{
	char *options;
	int optlen;

	options = xzalloc(1);
	optlen = 0;
	while (*++argv) {
	const char *fmt;
	const char *var;
	const char *val;

	var = *argv;
	options = xrealloc(options, optlen + 2 + strlen(var) + 2);
	fmt = "%.*s%s ";
	val = strchrnul(var, '=');
	if (quote_spaces) {
	/*
	* modprobe (module-init-tools version 3.11.1) compat:
	* quote only value:
	* var="val with spaces", not "var=val with spaces"
	* (note: var name is not checked for spaces!)
	*/
	if (val) { / has var=val format. skip '=' */
	val++;
	if (strchr(val, ' '))
	fmt = "%.*s\"%s\" ";
	}
	}
	optlen += sprintf(options + optlen, fmt, (int)(val - var), var, val);
	}
	/* Remove trailing space. Disabled */
	/* if (optlen != 0) options[optlen-1] = '\0'; */
	return options;
	}
	#endif

	#if ENABLE_FEATURE_INSMOD_TRY_MMAP
	void* FAST_FUNC try_to_mmap_module(const char filename, size_t image_size_p)
	{
	/* We have user reports of failure to load 3MB module
	* on a 16MB RAM machine. Apparently even a transient
	* memory spike to 6MB during module load
	* is too big for that system. */
	void *image;
	struct stat st;
	int fd;

	fd = xopen(filename, O_RDONLY);
	fstat(fd, &st);
	image = NULL;
	/* st.st_size is off_t, we can't just pass it to mmap */
	if (st.st_size <= *image_size_p) {
	size_t image_size = st.st_size;
	image = mmap(NULL, image_size, PROT_READ, MAP_PRIVATE, fd, 0);
	if (image == MAP_FAILED) {
	image = NULL;
	} else if ((uint32_t)image != SWAP_BE32(0x7f454C46)) {
	/* No ELF signature. Compressed module? */
	munmap(image, image_size);
	image = NULL;
	} else {
	/* Success. Report the size */
	*image_size_p = image_size;
	}
	}
	close(fd);
	return image;
	}
	#endif

	/* Return:
	* 0 on success,
	* -errno on open/read error,
	* errno on init_module() error
	*/
	int FAST_FUNC bb_init_module(const char filename, const char options)
	{
	size_t image_size;
	char *image;
	int rc;
	bool mmaped;

	if (!options)
	options = "";

	//TODO: audit bb_init_module_24 to match error code convention
	#if ENABLE_FEATURE_2_4_MODULES
	if (get_linux_version_code() < KERNEL_VERSION(2,6,0))
	return bb_init_module_24(filename, options);
	#endif

	/*
	* First we try finit_module if available. Some kernels are configured
	* to only allow loading of modules off of secure storage (like a read-
	* only rootfs) which needs the finit_module call. If it fails, we fall
	* back to normal module loading to support compressed modules.
	*/
	# ifdef __NR_finit_module
	{
	int fd = open(filename, O_RDONLY \| O_CLOEXEC);
	if (fd >= 0) {
	rc = finit_module(fd, options, 0) != 0;
	close(fd);
	if (rc == 0)
	return rc;
	}
	}
	# endif

	image_size = INT_MAX - 4095;
	mmaped = 0;
	image = try_to_mmap_module(filename, &image_size);
	if (image) {
	mmaped = 1;
	} else {
	errno = ENOMEM; /* may be changed by e.g. open errors below */
	image = xmalloc_open_zipped_read_close(filename, &image_size);
	if (!image)
	return -errno;
	}

	errno = 0;
	init_module(image, image_size, options);
	rc = errno;
	if (mmaped)
	munmap(image, image_size);
	else
	free(image);
	return rc;
	}

	int FAST_FUNC bb_delete_module(const char *module, unsigned int flags)
	{
	errno = 0;
	delete_module(module, flags);
	return errno;
	}

	/* Note: not suitable for delete_module() errnos.
	* For them, probably only EWOULDBLOCK needs explaining:
	* "Other modules depend on us". So far we don't do such
	* translation and don't use moderror() for removal errors.
	*/
	const char* FAST_FUNC moderror(int err)
	{
	switch (err) {
	case -1: /* btw: it's -EPERM */
	return "no such module";
	case ENOEXEC:
	return "invalid module format";
	case ENOENT:
	return "unknown symbol in module, or unknown parameter";
	case ESRCH:
	return "module has wrong symbol version";
	case ENOSYS:
	return "kernel does not support requested operation";
	}
	if (err < 0) /* should always be */
	err = -err;
	return strerror(err);
	}