jump label: Add jump_label_text_reserved() to reserve jump points
Add a jump_label_text_reserved(void *start, void *end), so that other pieces of code that want to modify kernel text, can first verify that jump label has not reserved the instruction. Acked-by: Masami Hiramatsu <mhiramat@redhat.com> Signed-off-by: Jason Baron <jbaron@redhat.com> LKML-Reference: <06236663a3a7b1c1f13576bb9eccb6d9c17b7bfe.1284733808.git.jbaron@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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@ -1218,7 +1218,8 @@ static int __kprobes copy_optimized_instructions(u8 *dest, u8 *src)
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}
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}
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/* Check whether the address range is reserved */
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/* Check whether the address range is reserved */
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if (ftrace_text_reserved(src, src + len - 1) ||
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if (ftrace_text_reserved(src, src + len - 1) ||
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alternatives_text_reserved(src, src + len - 1))
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alternatives_text_reserved(src, src + len - 1) ||
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jump_label_text_reserved(src, src + len - 1))
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return -EBUSY;
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return -EBUSY;
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return len;
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return len;
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@ -20,9 +20,10 @@ extern struct jump_entry __stop___jump_table[];
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extern void arch_jump_label_transform(struct jump_entry *entry,
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extern void arch_jump_label_transform(struct jump_entry *entry,
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enum jump_label_type type);
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enum jump_label_type type);
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extern void arch_jump_label_text_poke_early(jump_label_t addr);
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extern void jump_label_update(unsigned long key, enum jump_label_type type);
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extern void jump_label_update(unsigned long key, enum jump_label_type type);
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extern void jump_label_apply_nops(struct module *mod);
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extern void jump_label_apply_nops(struct module *mod);
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extern void arch_jump_label_text_poke_early(jump_label_t addr);
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extern int jump_label_text_reserved(void *start, void *end);
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#define enable_jump_label(key) \
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#define enable_jump_label(key) \
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jump_label_update((unsigned long)key, JUMP_LABEL_ENABLE);
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jump_label_update((unsigned long)key, JUMP_LABEL_ENABLE);
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@ -53,6 +54,11 @@ static inline int jump_label_apply_nops(struct module *mod)
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return 0;
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return 0;
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}
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}
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static inline int jump_label_text_reserved(void *start, void *end)
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{
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return 0;
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}
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#endif
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#endif
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#endif
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#endif
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@ -177,6 +177,89 @@ void jump_label_update(unsigned long key, enum jump_label_type type)
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mutex_unlock(&jump_label_mutex);
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mutex_unlock(&jump_label_mutex);
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}
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}
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static int addr_conflict(struct jump_entry *entry, void *start, void *end)
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{
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if (entry->code <= (unsigned long)end &&
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entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
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return 1;
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return 0;
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}
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#ifdef CONFIG_MODULES
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static int module_conflict(void *start, void *end)
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{
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struct hlist_head *head;
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struct hlist_node *node, *node_next, *module_node, *module_node_next;
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struct jump_label_entry *e;
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struct jump_label_module_entry *e_module;
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struct jump_entry *iter;
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int i, count;
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int conflict = 0;
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for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) {
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head = &jump_label_table[i];
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hlist_for_each_entry_safe(e, node, node_next, head, hlist) {
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hlist_for_each_entry_safe(e_module, module_node,
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module_node_next,
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&(e->modules), hlist) {
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count = e_module->nr_entries;
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iter = e_module->table;
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while (count--) {
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if (addr_conflict(iter, start, end)) {
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conflict = 1;
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goto out;
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}
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iter++;
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}
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}
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}
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}
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out:
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return conflict;
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}
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#endif
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/***
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* jump_label_text_reserved - check if addr range is reserved
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* @start: start text addr
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* @end: end text addr
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*
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* checks if the text addr located between @start and @end
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* overlaps with any of the jump label patch addresses. Code
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* that wants to modify kernel text should first verify that
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* it does not overlap with any of the jump label addresses.
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*
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* returns 1 if there is an overlap, 0 otherwise
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*/
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int jump_label_text_reserved(void *start, void *end)
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{
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struct jump_entry *iter;
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struct jump_entry *iter_start = __start___jump_table;
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struct jump_entry *iter_stop = __start___jump_table;
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int conflict = 0;
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mutex_lock(&jump_label_mutex);
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iter = iter_start;
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while (iter < iter_stop) {
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if (addr_conflict(iter, start, end)) {
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conflict = 1;
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goto out;
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}
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iter++;
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}
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/* now check modules */
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#ifdef CONFIG_MODULES
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conflict = module_conflict(start, end);
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#endif
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out:
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mutex_unlock(&jump_label_mutex);
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return conflict;
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}
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static __init int init_jump_label(void)
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static __init int init_jump_label(void)
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{
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{
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int ret;
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int ret;
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@ -1147,7 +1147,8 @@ int __kprobes register_kprobe(struct kprobe *p)
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preempt_disable();
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preempt_disable();
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if (!kernel_text_address((unsigned long) p->addr) ||
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if (!kernel_text_address((unsigned long) p->addr) ||
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in_kprobes_functions((unsigned long) p->addr) ||
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in_kprobes_functions((unsigned long) p->addr) ||
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ftrace_text_reserved(p->addr, p->addr)) {
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ftrace_text_reserved(p->addr, p->addr) ||
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jump_label_text_reserved(p->addr, p->addr)) {
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preempt_enable();
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preempt_enable();
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return -EINVAL;
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return -EINVAL;
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}
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}
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