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-rw-r--r--kernel/module.c329
1 files changed, 213 insertions, 116 deletions
diff --git a/kernel/module.c b/kernel/module.c
index 3c4fc4bb4b8..8c6b42840dd 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -72,7 +72,11 @@
/* If this is set, the section belongs in the init part of the module */
#define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))
-/* List of modules, protected by module_mutex or preempt_disable
+/*
+ * Mutex protects:
+ * 1) List of modules (also safely readable with preempt_disable),
+ * 2) module_use links,
+ * 3) module_addr_min/module_addr_max.
* (delete uses stop_machine/add uses RCU list operations). */
DEFINE_MUTEX(module_mutex);
EXPORT_SYMBOL_GPL(module_mutex);
@@ -90,7 +94,8 @@ static DECLARE_WAIT_QUEUE_HEAD(module_wq);
static BLOCKING_NOTIFIER_HEAD(module_notify_list);
-/* Bounds of module allocation, for speeding __module_address */
+/* Bounds of module allocation, for speeding __module_address.
+ * Protected by module_mutex. */
static unsigned long module_addr_min = -1UL, module_addr_max = 0;
int register_module_notifier(struct notifier_block * nb)
@@ -180,8 +185,6 @@ extern const struct kernel_symbol __start___ksymtab_gpl[];
extern const struct kernel_symbol __stop___ksymtab_gpl[];
extern const struct kernel_symbol __start___ksymtab_gpl_future[];
extern const struct kernel_symbol __stop___ksymtab_gpl_future[];
-extern const struct kernel_symbol __start___ksymtab_gpl_future[];
-extern const struct kernel_symbol __stop___ksymtab_gpl_future[];
extern const unsigned long __start___kcrctab[];
extern const unsigned long __start___kcrctab_gpl[];
extern const unsigned long __start___kcrctab_gpl_future[];
@@ -331,7 +334,7 @@ static bool find_symbol_in_section(const struct symsearch *syms,
}
/* Find a symbol and return it, along with, (optional) crc and
- * (optional) module which owns it */
+ * (optional) module which owns it. Needs preempt disabled or module_mutex. */
const struct kernel_symbol *find_symbol(const char *name,
struct module **owner,
const unsigned long **crc,
@@ -405,7 +408,7 @@ static unsigned int find_pcpusec(Elf_Ehdr *hdr,
Elf_Shdr *sechdrs,
const char *secstrings)
{
- return find_sec(hdr, sechdrs, secstrings, ".data.percpu");
+ return find_sec(hdr, sechdrs, secstrings, ".data..percpu");
}
static void percpu_modcopy(struct module *mod,
@@ -525,7 +528,8 @@ static void module_unload_init(struct module *mod)
{
int cpu;
- INIT_LIST_HEAD(&mod->modules_which_use_me);
+ INIT_LIST_HEAD(&mod->source_list);
+ INIT_LIST_HEAD(&mod->target_list);
for_each_possible_cpu(cpu) {
per_cpu_ptr(mod->refptr, cpu)->incs = 0;
per_cpu_ptr(mod->refptr, cpu)->decs = 0;
@@ -537,20 +541,13 @@ static void module_unload_init(struct module *mod)
mod->waiter = current;
}
-/* modules using other modules */
-struct module_use
-{
- struct list_head list;
- struct module *module_which_uses;
-};
-
/* Does a already use b? */
static int already_uses(struct module *a, struct module *b)
{
struct module_use *use;
- list_for_each_entry(use, &b->modules_which_use_me, list) {
- if (use->module_which_uses == a) {
+ list_for_each_entry(use, &b->source_list, source_list) {
+ if (use->source == a) {
DEBUGP("%s uses %s!\n", a->name, b->name);
return 1;
}
@@ -559,62 +556,68 @@ static int already_uses(struct module *a, struct module *b)
return 0;
}
-/* Module a uses b */
-int use_module(struct module *a, struct module *b)
+/*
+ * Module a uses b
+ * - we add 'a' as a "source", 'b' as a "target" of module use
+ * - the module_use is added to the list of 'b' sources (so
+ * 'b' can walk the list to see who sourced them), and of 'a'
+ * targets (so 'a' can see what modules it targets).
+ */
+static int add_module_usage(struct module *a, struct module *b)
{
struct module_use *use;
- int no_warn, err;
- if (b == NULL || already_uses(a, b)) return 1;
+ DEBUGP("Allocating new usage for %s.\n", a->name);
+ use = kmalloc(sizeof(*use), GFP_ATOMIC);
+ if (!use) {
+ printk(KERN_WARNING "%s: out of memory loading\n", a->name);
+ return -ENOMEM;
+ }
+
+ use->source = a;
+ use->target = b;
+ list_add(&use->source_list, &b->source_list);
+ list_add(&use->target_list, &a->target_list);
+ return 0;
+}
- /* If we're interrupted or time out, we fail. */
- if (wait_event_interruptible_timeout(
- module_wq, (err = strong_try_module_get(b)) != -EBUSY,
- 30 * HZ) <= 0) {
- printk("%s: gave up waiting for init of module %s.\n",
- a->name, b->name);
+/* Module a uses b: caller needs module_mutex() */
+int ref_module(struct module *a, struct module *b)
+{
+ int err;
+
+ if (b == NULL || already_uses(a, b))
return 0;
- }
- /* If strong_try_module_get() returned a different error, we fail. */
+ /* If module isn't available, we fail. */
+ err = strong_try_module_get(b);
if (err)
- return 0;
+ return err;
- DEBUGP("Allocating new usage for %s.\n", a->name);
- use = kmalloc(sizeof(*use), GFP_ATOMIC);
- if (!use) {
- printk("%s: out of memory loading\n", a->name);
+ err = add_module_usage(a, b);
+ if (err) {
module_put(b);
- return 0;
+ return err;
}
-
- use->module_which_uses = a;
- list_add(&use->list, &b->modules_which_use_me);
- no_warn = sysfs_create_link(b->holders_dir, &a->mkobj.kobj, a->name);
- return 1;
+ return 0;
}
-EXPORT_SYMBOL_GPL(use_module);
+EXPORT_SYMBOL_GPL(ref_module);
/* Clear the unload stuff of the module. */
static void module_unload_free(struct module *mod)
{
- struct module *i;
-
- list_for_each_entry(i, &modules, list) {
- struct module_use *use;
+ struct module_use *use, *tmp;
- list_for_each_entry(use, &i->modules_which_use_me, list) {
- if (use->module_which_uses == mod) {
- DEBUGP("%s unusing %s\n", mod->name, i->name);
- module_put(i);
- list_del(&use->list);
- kfree(use);
- sysfs_remove_link(i->holders_dir, mod->name);
- /* There can be at most one match. */
- break;
- }
- }
+ mutex_lock(&module_mutex);
+ list_for_each_entry_safe(use, tmp, &mod->target_list, target_list) {
+ struct module *i = use->target;
+ DEBUGP("%s unusing %s\n", mod->name, i->name);
+ module_put(i);
+ list_del(&use->source_list);
+ list_del(&use->target_list);
+ kfree(use);
}
+ mutex_unlock(&module_mutex);
}
#ifdef CONFIG_MODULE_FORCE_UNLOAD
@@ -737,7 +740,7 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
goto out;
}
- if (!list_empty(&mod->modules_which_use_me)) {
+ if (!list_empty(&mod->source_list)) {
/* Other modules depend on us: get rid of them first. */
ret = -EWOULDBLOCK;
goto out;
@@ -781,13 +784,14 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_GOING, mod);
async_synchronize_full();
- mutex_lock(&module_mutex);
+
/* Store the name of the last unloaded module for diagnostic purposes */
strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module));
ddebug_remove_module(mod->name);
- free_module(mod);
- out:
+ free_module(mod);
+ return 0;
+out:
mutex_unlock(&module_mutex);
return ret;
}
@@ -801,9 +805,9 @@ static inline void print_unload_info(struct seq_file *m, struct module *mod)
/* Always include a trailing , so userspace can differentiate
between this and the old multi-field proc format. */
- list_for_each_entry(use, &mod->modules_which_use_me, list) {
+ list_for_each_entry(use, &mod->source_list, source_list) {
printed_something = 1;
- seq_printf(m, "%s,", use->module_which_uses->name);
+ seq_printf(m, "%s,", use->source->name);
}
if (mod->init != NULL && mod->exit == NULL) {
@@ -882,11 +886,11 @@ static inline void module_unload_free(struct module *mod)
{
}
-int use_module(struct module *a, struct module *b)
+int ref_module(struct module *a, struct module *b)
{
- return strong_try_module_get(b) == 0;
+ return strong_try_module_get(b);
}
-EXPORT_SYMBOL_GPL(use_module);
+EXPORT_SYMBOL_GPL(ref_module);
static inline void module_unload_init(struct module *mod)
{
@@ -1003,6 +1007,8 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs,
{
const unsigned long *crc;
+ /* Since this should be found in kernel (which can't be removed),
+ * no locking is necessary. */
if (!find_symbol(MODULE_SYMBOL_PREFIX "module_layout", NULL,
&crc, true, false))
BUG();
@@ -1045,29 +1051,62 @@ static inline int same_magic(const char *amagic, const char *bmagic,
}
#endif /* CONFIG_MODVERSIONS */
-/* Resolve a symbol for this module. I.e. if we find one, record usage.
- Must be holding module_mutex. */
+/* Resolve a symbol for this module. I.e. if we find one, record usage. */
static const struct kernel_symbol *resolve_symbol(Elf_Shdr *sechdrs,
unsigned int versindex,
const char *name,
- struct module *mod)
+ struct module *mod,
+ char ownername[])
{
struct module *owner;
const struct kernel_symbol *sym;
const unsigned long *crc;
+ int err;
+ mutex_lock(&module_mutex);
sym = find_symbol(name, &owner, &crc,
!(mod->taints & (1 << TAINT_PROPRIETARY_MODULE)), true);
- /* use_module can fail due to OOM,
- or module initialization or unloading */
- if (sym) {
- if (!check_version(sechdrs, versindex, name, mod, crc, owner)
- || !use_module(mod, owner))
- sym = NULL;
+ if (!sym)
+ goto unlock;
+
+ if (!check_version(sechdrs, versindex, name, mod, crc, owner)) {
+ sym = ERR_PTR(-EINVAL);
+ goto getname;
}
+
+ err = ref_module(mod, owner);
+ if (err) {
+ sym = ERR_PTR(err);
+ goto getname;
+ }
+
+getname:
+ /* We must make copy under the lock if we failed to get ref. */
+ strncpy(ownername, module_name(owner), MODULE_NAME_LEN);
+unlock:
+ mutex_unlock(&module_mutex);
return sym;
}
+static const struct kernel_symbol *resolve_symbol_wait(Elf_Shdr *sechdrs,
+ unsigned int versindex,
+ const char *name,
+ struct module *mod)
+{
+ const struct kernel_symbol *ksym;
+ char ownername[MODULE_NAME_LEN];
+
+ if (wait_event_interruptible_timeout(module_wq,
+ !IS_ERR(ksym = resolve_symbol(sechdrs, versindex, name,
+ mod, ownername)) ||
+ PTR_ERR(ksym) != -EBUSY,
+ 30 * HZ) <= 0) {
+ printk(KERN_WARNING "%s: gave up waiting for init of module %s.\n",
+ mod->name, ownername);
+ }
+ return ksym;
+}
+
/*
* /sys/module/foo/sections stuff
* J. Corbet <corbet@lwn.net>
@@ -1297,7 +1336,34 @@ static inline void remove_notes_attrs(struct module *mod)
#endif
#ifdef CONFIG_SYSFS
-int module_add_modinfo_attrs(struct module *mod)
+static void add_usage_links(struct module *mod)
+{
+#ifdef CONFIG_MODULE_UNLOAD
+ struct module_use *use;
+ int nowarn;
+
+ mutex_lock(&module_mutex);
+ list_for_each_entry(use, &mod->target_list, target_list) {
+ nowarn = sysfs_create_link(use->target->holders_dir,
+ &mod->mkobj.kobj, mod->name);
+ }
+ mutex_unlock(&module_mutex);
+#endif
+}
+
+static void del_usage_links(struct module *mod)
+{
+#ifdef CONFIG_MODULE_UNLOAD
+ struct module_use *use;
+
+ mutex_lock(&module_mutex);
+ list_for_each_entry(use, &mod->target_list, target_list)
+ sysfs_remove_link(use->target->holders_dir, mod->name);
+ mutex_unlock(&module_mutex);
+#endif
+}
+
+static int module_add_modinfo_attrs(struct module *mod)
{
struct module_attribute *attr;
struct module_attribute *temp_attr;
@@ -1323,7 +1389,7 @@ int module_add_modinfo_attrs(struct module *mod)
return error;
}
-void module_remove_modinfo_attrs(struct module *mod)
+static void module_remove_modinfo_attrs(struct module *mod)
{
struct module_attribute *attr;
int i;
@@ -1339,7 +1405,7 @@ void module_remove_modinfo_attrs(struct module *mod)
kfree(mod->modinfo_attrs);
}
-int mod_sysfs_init(struct module *mod)
+static int mod_sysfs_init(struct module *mod)
{
int err;
struct kobject *kobj;
@@ -1373,12 +1439,16 @@ out:
return err;
}
-int mod_sysfs_setup(struct module *mod,
+static int mod_sysfs_setup(struct module *mod,
struct kernel_param *kparam,
unsigned int num_params)
{
int err;
+ err = mod_sysfs_init(mod);
+ if (err)
+ goto out;
+
mod->holders_dir = kobject_create_and_add("holders", &mod->mkobj.kobj);
if (!mod->holders_dir) {
err = -ENOMEM;
@@ -1393,6 +1463,8 @@ int mod_sysfs_setup(struct module *mod,
if (err)
goto out_unreg_param;
+ add_usage_links(mod);
+
kobject_uevent(&mod->mkobj.kobj, KOBJ_ADD);
return 0;
@@ -1402,6 +1474,7 @@ out_unreg_holders:
kobject_put(mod->holders_dir);
out_unreg:
kobject_put(&mod->mkobj.kobj);
+out:
return err;
}
@@ -1412,14 +1485,40 @@ static void mod_sysfs_fini(struct module *mod)
#else /* CONFIG_SYSFS */
+static inline int mod_sysfs_init(struct module *mod)
+{
+ return 0;
+}
+
+static inline int mod_sysfs_setup(struct module *mod,
+ struct kernel_param *kparam,
+ unsigned int num_params)
+{
+ return 0;
+}
+
+static inline int module_add_modinfo_attrs(struct module *mod)
+{
+ return 0;
+}
+
+static inline void module_remove_modinfo_attrs(struct module *mod)
+{
+}
+
static void mod_sysfs_fini(struct module *mod)
{
}
+static void del_usage_links(struct module *mod)
+{
+}
+
#endif /* CONFIG_SYSFS */
static void mod_kobject_remove(struct module *mod)
{
+ del_usage_links(mod);
module_remove_modinfo_attrs(mod);
module_param_sysfs_remove(mod);
kobject_put(mod->mkobj.drivers_dir);
@@ -1438,13 +1537,15 @@ static int __unlink_module(void *_mod)
return 0;
}
-/* Free a module, remove from lists, etc (must hold module_mutex). */
+/* Free a module, remove from lists, etc. */
static void free_module(struct module *mod)
{
trace_module_free(mod);
/* Delete from various lists */
+ mutex_lock(&module_mutex);
stop_machine(__unlink_module, mod, NULL);
+ mutex_unlock(&module_mutex);
remove_notes_attrs(mod);
remove_sect_attrs(mod);
mod_kobject_remove(mod);
@@ -1495,6 +1596,8 @@ EXPORT_SYMBOL_GPL(__symbol_get);
/*
* Ensure that an exported symbol [global namespace] does not already exist
* in the kernel or in some other module's exported symbol table.
+ *
+ * You must hold the module_mutex.
*/
static int verify_export_symbols(struct module *mod)
{
@@ -1560,21 +1663,23 @@ static int simplify_symbols(Elf_Shdr *sechdrs,
break;
case SHN_UNDEF:
- ksym = resolve_symbol(sechdrs, versindex,
- strtab + sym[i].st_name, mod);
+ ksym = resolve_symbol_wait(sechdrs, versindex,
+ strtab + sym[i].st_name,
+ mod);
/* Ok if resolved. */
- if (ksym) {
+ if (ksym && !IS_ERR(ksym)) {
sym[i].st_value = ksym->value;
break;
}
/* Ok if weak. */
- if (ELF_ST_BIND(sym[i].st_info) == STB_WEAK)
+ if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK)
break;
- printk(KERN_WARNING "%s: Unknown symbol %s\n",
- mod->name, strtab + sym[i].st_name);
- ret = -ENOENT;
+ printk(KERN_WARNING "%s: Unknown symbol %s (err %li)\n",
+ mod->name, strtab + sym[i].st_name,
+ PTR_ERR(ksym));
+ ret = PTR_ERR(ksym) ?: -ENOENT;
break;
default:
@@ -1962,11 +2067,13 @@ static void *module_alloc_update_bounds(unsigned long size)
void *ret = module_alloc(size);
if (ret) {
+ mutex_lock(&module_mutex);
/* Update module bounds. */
if ((unsigned long)ret < module_addr_min)
module_addr_min = (unsigned long)ret;
if ((unsigned long)ret + size > module_addr_max)
module_addr_max = (unsigned long)ret + size;
+ mutex_unlock(&module_mutex);
}
return ret;
}
@@ -2016,6 +2123,7 @@ static noinline struct module *load_module(void __user *umod,
long err = 0;
void *ptr = NULL; /* Stops spurious gcc warning */
unsigned long symoffs, stroffs, *strmap;
+ void __percpu *percpu;
mm_segment_t old_fs;
@@ -2140,11 +2248,6 @@ static noinline struct module *load_module(void __user *umod,
goto free_mod;
}
- if (find_module(mod->name)) {
- err = -EEXIST;
- goto free_mod;
- }
-
mod->state = MODULE_STATE_COMING;
/* Allow arches to frob section contents and sizes. */
@@ -2160,6 +2263,8 @@ static noinline struct module *load_module(void __user *umod,
goto free_mod;
sechdrs[pcpuindex].sh_flags &= ~(unsigned long)SHF_ALLOC;
}
+ /* Keep this around for failure path. */
+ percpu = mod_percpu(mod);
/* Determine total sizes, and put offsets in sh_entsize. For now
this is done generically; there doesn't appear to be any
@@ -2233,11 +2338,6 @@ static noinline struct module *load_module(void __user *umod,
/* Now we've moved module, initialize linked lists, etc. */
module_unload_init(mod);
- /* add kobject, so we can reference it. */
- err = mod_sysfs_init(mod);
- if (err)
- goto free_unload;
-
/* Set up license info based on the info section */
set_license(mod, get_modinfo(sechdrs, infoindex, "license"));
@@ -2362,11 +2462,6 @@ static noinline struct module *load_module(void __user *umod,
goto cleanup;
}
- /* Find duplicate symbols */
- err = verify_export_symbols(mod);
- if (err < 0)
- goto cleanup;
-
/* Set up and sort exception table */
mod->extable = section_objs(hdr, sechdrs, secstrings, "__ex_table",
sizeof(*mod->extable), &mod->num_exentries);
@@ -2425,7 +2520,19 @@ static noinline struct module *load_module(void __user *umod,
* function to insert in a way safe to concurrent readers.
* The mutex protects against concurrent writers.
*/
+ mutex_lock(&module_mutex);
+ if (find_module(mod->name)) {
+ err = -EEXIST;
+ goto unlock;
+ }
+
+ /* Find duplicate symbols */
+ err = verify_export_symbols(mod);
+ if (err < 0)
+ goto unlock;
+
list_add_rcu(&mod->list, &modules);
+ mutex_unlock(&module_mutex);
err = parse_args(mod->name, mod->args, mod->kp, mod->num_kp, NULL);
if (err < 0)
@@ -2434,6 +2541,7 @@ static noinline struct module *load_module(void __user *umod,
err = mod_sysfs_setup(mod, mod->kp, mod->num_kp);
if (err < 0)
goto unlink;
+
add_sect_attrs(mod, hdr->e_shnum, secstrings, sechdrs);
add_notes_attrs(mod, hdr->e_shnum, secstrings, sechdrs);
@@ -2446,15 +2554,15 @@ static noinline struct module *load_module(void __user *umod,
return mod;
unlink:
+ mutex_lock(&module_mutex);
/* Unlink carefully: kallsyms could be walking list. */
list_del_rcu(&mod->list);
+ unlock:
+ mutex_unlock(&module_mutex);
synchronize_sched();
module_arch_cleanup(mod);
cleanup:
free_modinfo(mod);
- kobject_del(&mod->mkobj.kobj);
- kobject_put(&mod->mkobj.kobj);
- free_unload:
module_unload_free(mod);
#if defined(CONFIG_MODULE_UNLOAD)
free_percpu(mod->refptr);
@@ -2465,7 +2573,7 @@ static noinline struct module *load_module(void __user *umod,
module_free(mod, mod->module_core);
/* mod will be freed with core. Don't access it beyond this line! */
free_percpu:
- percpu_modfree(mod);
+ free_percpu(percpu);
free_mod:
kfree(args);
kfree(strmap);
@@ -2501,19 +2609,10 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
if (!capable(CAP_SYS_MODULE) || modules_disabled)
return -EPERM;
- /* Only one module load at a time, please */
- if (mutex_lock_interruptible(&module_mutex) != 0)
- return -EINTR;
-
/* Do all the hard work */
mod = load_module(umod, len, uargs);
- if (IS_ERR(mod)) {
- mutex_unlock(&module_mutex);
+ if (IS_ERR(mod))
return PTR_ERR(mod);
- }
-
- /* Drop lock so they can recurse */
- mutex_unlock(&module_mutex);
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_COMING, mod);
@@ -2530,9 +2629,7 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
module_put(mod);
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_GOING, mod);
- mutex_lock(&module_mutex);
free_module(mod);
- mutex_unlock(&module_mutex);
wake_up(&module_wq);
return ret;
}
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2024-12-14 13:21:37 +0000