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On some systems like Chromium OS, loading modules from non-verified filesystems is denied. Only finit_module is allowed because an open fd is passed which can be checked against a verified location. Change the module loading code to first attempt finit_module and if that fails for whatever reason, fall back to the existing logic. On x86_64, this adds ~80 bytes to modutils/modutils.o and ~68 bytes to modutils/modprobe-small.o. Signed-off-by: Mike Frysinger <vapier@chromium.org> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
288 lines
6.8 KiB
C
288 lines
6.8 KiB
C
/*
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* Common modutils related functions for busybox
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*
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* Copyright (C) 2008 by Timo Teras <timo.teras@iki.fi>
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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#include "modutils.h"
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#ifdef __UCLIBC__
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extern int init_module(void *module, unsigned long len, const char *options);
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extern int delete_module(const char *module, unsigned int flags);
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#else
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# include <sys/syscall.h>
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# define init_module(mod, len, opts) syscall(__NR_init_module, mod, len, opts)
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# if defined(__NR_finit_module)
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# define finit_module(fd, uargs, flags) syscall(__NR_finit_module, fd, uargs, flags)
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# endif
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# define delete_module(mod, flags) syscall(__NR_delete_module, mod, flags)
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#endif
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static module_entry *helper_get_module(module_db *db, const char *module, int create)
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{
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char modname[MODULE_NAME_LEN];
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struct module_entry *e;
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unsigned i, hash;
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filename2modname(module, modname);
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hash = 0;
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for (i = 0; modname[i]; i++)
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hash = ((hash << 5) + hash) + modname[i];
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hash %= MODULE_HASH_SIZE;
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for (e = db->buckets[hash]; e; e = e->next)
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if (strcmp(e->modname, modname) == 0)
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return e;
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if (!create)
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return NULL;
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e = xzalloc(sizeof(*e));
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e->modname = xstrdup(modname);
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e->next = db->buckets[hash];
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db->buckets[hash] = e;
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IF_DEPMOD(e->dnext = e->dprev = e;)
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return e;
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}
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module_entry* FAST_FUNC moddb_get(module_db *db, const char *module)
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{
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return helper_get_module(db, module, 0);
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}
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module_entry* FAST_FUNC moddb_get_or_create(module_db *db, const char *module)
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{
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return helper_get_module(db, module, 1);
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}
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void FAST_FUNC moddb_free(module_db *db)
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{
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module_entry *e, *n;
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unsigned i;
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for (i = 0; i < MODULE_HASH_SIZE; i++) {
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for (e = db->buckets[i]; e; e = n) {
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n = e->next;
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free(e->name);
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free(e->modname);
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free(e);
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}
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}
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}
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void FAST_FUNC replace(char *s, char what, char with)
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{
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while (*s) {
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if (what == *s)
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*s = with;
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++s;
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}
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}
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char* FAST_FUNC replace_underscores(char *s)
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{
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replace(s, '-', '_');
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return s;
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}
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int FAST_FUNC string_to_llist(char *string, llist_t **llist, const char *delim)
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{
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char *tok;
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int len = 0;
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while ((tok = strsep(&string, delim)) != NULL) {
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if (tok[0] == '\0')
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continue;
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llist_add_to_end(llist, xstrdup(tok));
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len += strlen(tok);
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}
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return len;
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}
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char* FAST_FUNC filename2modname(const char *filename, char *modname)
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{
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char local_modname[MODULE_NAME_LEN];
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int i;
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const char *from;
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if (filename == NULL)
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return NULL;
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if (modname == NULL)
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modname = local_modname;
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// Disabled since otherwise "modprobe dir/name" would work
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// as if it is "modprobe name". It is unclear why
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// 'basenamization' was here in the first place.
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//from = bb_get_last_path_component_nostrip(filename);
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from = filename;
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for (i = 0; i < (MODULE_NAME_LEN-1) && from[i] != '\0' && from[i] != '.'; i++)
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modname[i] = (from[i] == '-') ? '_' : from[i];
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modname[i] = '\0';
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if (modname == local_modname)
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return xstrdup(modname);
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return modname;
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}
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char* FAST_FUNC parse_cmdline_module_options(char **argv, int quote_spaces)
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{
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char *options;
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int optlen;
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options = xzalloc(1);
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optlen = 0;
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while (*++argv) {
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const char *fmt;
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const char *var;
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const char *val;
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var = *argv;
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options = xrealloc(options, optlen + 2 + strlen(var) + 2);
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fmt = "%.*s%s ";
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val = strchrnul(var, '=');
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if (quote_spaces) {
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/*
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* modprobe (module-init-tools version 3.11.1) compat:
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* quote only value:
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* var="val with spaces", not "var=val with spaces"
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* (note: var *name* is not checked for spaces!)
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*/
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if (*val) { /* has var=val format. skip '=' */
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val++;
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if (strchr(val, ' '))
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fmt = "%.*s\"%s\" ";
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}
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}
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optlen += sprintf(options + optlen, fmt, (int)(val - var), var, val);
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}
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/* Remove trailing space. Disabled */
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/* if (optlen != 0) options[optlen-1] = '\0'; */
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return options;
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}
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#if ENABLE_FEATURE_INSMOD_TRY_MMAP
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void* FAST_FUNC try_to_mmap_module(const char *filename, size_t *image_size_p)
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{
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/* We have user reports of failure to load 3MB module
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* on a 16MB RAM machine. Apparently even a transient
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* memory spike to 6MB during module load
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* is too big for that system. */
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void *image;
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struct stat st;
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int fd;
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fd = xopen(filename, O_RDONLY);
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fstat(fd, &st);
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image = NULL;
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/* st.st_size is off_t, we can't just pass it to mmap */
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if (st.st_size <= *image_size_p) {
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size_t image_size = st.st_size;
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image = mmap(NULL, image_size, PROT_READ, MAP_PRIVATE, fd, 0);
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if (image == MAP_FAILED) {
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image = NULL;
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} else if (*(uint32_t*)image != SWAP_BE32(0x7f454C46)) {
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/* No ELF signature. Compressed module? */
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munmap(image, image_size);
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image = NULL;
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} else {
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/* Success. Report the size */
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*image_size_p = image_size;
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}
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}
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close(fd);
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return image;
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}
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#endif
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/* Return:
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* 0 on success,
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* -errno on open/read error,
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* errno on init_module() error
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*/
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int FAST_FUNC bb_init_module(const char *filename, const char *options)
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{
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size_t image_size;
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char *image;
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int rc;
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bool mmaped;
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if (!options)
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options = "";
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//TODO: audit bb_init_module_24 to match error code convention
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#if ENABLE_FEATURE_2_4_MODULES
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if (get_linux_version_code() < KERNEL_VERSION(2,6,0))
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return bb_init_module_24(filename, options);
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#endif
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/*
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* First we try finit_module if available. Some kernels are configured
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* to only allow loading of modules off of secure storage (like a read-
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* only rootfs) which needs the finit_module call. If it fails, we fall
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* back to normal module loading to support compressed modules.
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*/
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# ifdef __NR_finit_module
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{
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int fd = open(filename, O_RDONLY | O_CLOEXEC);
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if (fd >= 0) {
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rc = finit_module(fd, options, 0) != 0;
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close(fd);
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if (rc == 0)
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return rc;
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}
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}
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# endif
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image_size = INT_MAX - 4095;
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mmaped = 0;
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image = try_to_mmap_module(filename, &image_size);
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if (image) {
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mmaped = 1;
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} else {
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errno = ENOMEM; /* may be changed by e.g. open errors below */
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image = xmalloc_open_zipped_read_close(filename, &image_size);
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if (!image)
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return -errno;
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}
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errno = 0;
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init_module(image, image_size, options);
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rc = errno;
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if (mmaped)
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munmap(image, image_size);
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else
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free(image);
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return rc;
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}
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int FAST_FUNC bb_delete_module(const char *module, unsigned int flags)
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{
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errno = 0;
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delete_module(module, flags);
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return errno;
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}
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/* Note: not suitable for delete_module() errnos.
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* For them, probably only EWOULDBLOCK needs explaining:
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* "Other modules depend on us". So far we don't do such
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* translation and don't use moderror() for removal errors.
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*/
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const char* FAST_FUNC moderror(int err)
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{
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switch (err) {
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case -1: /* btw: it's -EPERM */
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return "no such module";
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case ENOEXEC:
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return "invalid module format";
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case ENOENT:
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return "unknown symbol in module, or unknown parameter";
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case ESRCH:
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return "module has wrong symbol version";
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case ENOSYS:
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return "kernel does not support requested operation";
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}
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if (err < 0) /* should always be */
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err = -err;
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return strerror(err);
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}
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