The following commit has been merged into the core/static_call branch of tip: Commit-ID: 6333e8f73b834f54e395a056e6002403f0862c51 Gitweb: https://git.kernel.org/tip/6333e8f73b834f54e395a056e6002403f0862c51 Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Tue, 18 Aug 2020 15:57:43 +02:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Tue, 01 Sep 2020 09:58:04 +02:00 static_call: Avoid kprobes on inline static_call()s Similar to how we disallow kprobes on any other dynamic text (ftrace/jump_label) also disallow kprobes on inline static_call()s. Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Link: https://lore.kernel.org/r/20200818135804.744920586@xxxxxxxxxxxxx --- arch/x86/kernel/kprobes/opt.c | 4 +- include/linux/static_call.h | 11 ++++++- kernel/kprobes.c | 2 +- kernel/static_call.c | 68 ++++++++++++++++++++++++++++++++++- 4 files changed, 84 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index 40f3804..c068e21 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -18,6 +18,7 @@ #include <linux/ftrace.h> #include <linux/frame.h> #include <linux/pgtable.h> +#include <linux/static_call.h> #include <asm/text-patching.h> #include <asm/cacheflush.h> @@ -210,7 +211,8 @@ static int copy_optimized_instructions(u8 *dest, u8 *src, u8 *real) /* Check whether the address range is reserved */ if (ftrace_text_reserved(src, src + len - 1) || alternatives_text_reserved(src, src + len - 1) || - jump_label_text_reserved(src, src + len - 1)) + jump_label_text_reserved(src, src + len - 1) || + static_call_text_reserved(src, src + len - 1)) return -EBUSY; return len; diff --git a/include/linux/static_call.h b/include/linux/static_call.h index 0d7f9ef..6f62ced 100644 --- a/include/linux/static_call.h +++ b/include/linux/static_call.h @@ -110,6 +110,7 @@ struct static_call_key { extern void __static_call_update(struct static_call_key *key, void *tramp, void *func); extern int static_call_mod_init(struct module *mod); +extern int static_call_text_reserved(void *start, void *end); #define DEFINE_STATIC_CALL(name, _func) \ DECLARE_STATIC_CALL(name, _func); \ @@ -153,6 +154,11 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func) cpus_read_unlock(); } +static inline int static_call_text_reserved(void *start, void *end) +{ + return 0; +} + #define EXPORT_STATIC_CALL(name) \ EXPORT_SYMBOL(STATIC_CALL_KEY(name)); \ EXPORT_SYMBOL(STATIC_CALL_TRAMP(name)) @@ -182,6 +188,11 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func) WRITE_ONCE(key->func, func); } +static inline int static_call_text_reserved(void *start, void *end) +{ + return 0; +} + #define EXPORT_STATIC_CALL(name) EXPORT_SYMBOL(STATIC_CALL_KEY(name)) #define EXPORT_STATIC_CALL_GPL(name) EXPORT_SYMBOL_GPL(STATIC_CALL_KEY(name)) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 287b263..67e6a8c 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -36,6 +36,7 @@ #include <linux/cpu.h> #include <linux/jump_label.h> #include <linux/perf_event.h> +#include <linux/static_call.h> #include <asm/sections.h> #include <asm/cacheflush.h> @@ -1634,6 +1635,7 @@ static int check_kprobe_address_safe(struct kprobe *p, if (!kernel_text_address((unsigned long) p->addr) || within_kprobe_blacklist((unsigned long) p->addr) || jump_label_text_reserved(p->addr, p->addr) || + static_call_text_reserved(p->addr, p->addr) || find_bug((unsigned long)p->addr)) { ret = -EINVAL; goto out; diff --git a/kernel/static_call.c b/kernel/static_call.c index d243492..753b2f1 100644 --- a/kernel/static_call.c +++ b/kernel/static_call.c @@ -204,8 +204,58 @@ static int __static_call_init(struct module *mod, return 0; } +static int addr_conflict(struct static_call_site *site, void *start, void *end) +{ + unsigned long addr = (unsigned long)static_call_addr(site); + + if (addr <= (unsigned long)end && + addr + CALL_INSN_SIZE > (unsigned long)start) + return 1; + + return 0; +} + +static int __static_call_text_reserved(struct static_call_site *iter_start, + struct static_call_site *iter_stop, + void *start, void *end) +{ + struct static_call_site *iter = iter_start; + + while (iter < iter_stop) { + if (addr_conflict(iter, start, end)) + return 1; + iter++; + } + + return 0; +} + #ifdef CONFIG_MODULES +static int __static_call_mod_text_reserved(void *start, void *end) +{ + struct module *mod; + int ret; + + preempt_disable(); + mod = __module_text_address((unsigned long)start); + WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); + if (!try_module_get(mod)) + mod = NULL; + preempt_enable(); + + if (!mod) + return 0; + + ret = __static_call_text_reserved(mod->static_call_sites, + mod->static_call_sites + mod->num_static_call_sites, + start, end); + + module_put(mod); + + return ret; +} + static int static_call_add_module(struct module *mod) { return __static_call_init(mod, mod->static_call_sites, @@ -273,8 +323,26 @@ static struct notifier_block static_call_module_nb = { .notifier_call = static_call_module_notify, }; +#else + +static inline int __static_call_mod_text_reserved(void *start, void *end) +{ + return 0; +} + #endif /* CONFIG_MODULES */ +int static_call_text_reserved(void *start, void *end) +{ + int ret = __static_call_text_reserved(__start_static_call_sites, + __stop_static_call_sites, start, end); + + if (ret) + return ret; + + return __static_call_mod_text_reserved(start, end); +} + static void __init static_call_init(void) { int ret;
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