diff options
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/Kconfig | 26 | ||||
| -rw-r--r-- | kernel/trace/Makefile | 2 | ||||
| -rw-r--r-- | kernel/trace/bpf_trace.c | 353 | ||||
| -rw-r--r-- | kernel/trace/fprobe.c | 332 | ||||
| -rw-r--r-- | kernel/trace/ftrace.c | 58 | ||||
| -rw-r--r-- | kernel/trace/rethook.c | 317 |
6 files changed, 1077 insertions, 11 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 16a52a71732d..9bb54c0b3b2d 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -10,6 +10,17 @@ config USER_STACKTRACE_SUPPORT config NOP_TRACER bool +config HAVE_RETHOOK + bool + +config RETHOOK + bool + depends on HAVE_RETHOOK + help + Enable generic return hooking feature. This is an internal + API, which will be used by other function-entry hooking + features like fprobe and kprobes. + config HAVE_FUNCTION_TRACER bool help @@ -236,6 +247,21 @@ config DYNAMIC_FTRACE_WITH_ARGS depends on DYNAMIC_FTRACE depends on HAVE_DYNAMIC_FTRACE_WITH_ARGS +config FPROBE + bool "Kernel Function Probe (fprobe)" + depends on FUNCTION_TRACER + depends on DYNAMIC_FTRACE_WITH_REGS + depends on HAVE_RETHOOK + select RETHOOK + default n + help + This option enables kernel function probe (fprobe) based on ftrace. + The fprobe is similar to kprobes, but probes only for kernel function + entries and exits. This also can probe multiple functions by one + fprobe. + + If unsure, say N. + config FUNCTION_PROFILER bool "Kernel function profiler" depends on FUNCTION_TRACER diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 19ef3758da95..d77cd8032213 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -98,6 +98,8 @@ obj-$(CONFIG_PROBE_EVENTS) += trace_probe.o obj-$(CONFIG_UPROBE_EVENTS) += trace_uprobe.o obj-$(CONFIG_BOOTTIME_TRACING) += trace_boot.o obj-$(CONFIG_FTRACE_RECORD_RECURSION) += trace_recursion_record.o +obj-$(CONFIG_FPROBE) += fprobe.o +obj-$(CONFIG_RETHOOK) += rethook.o obj-$(CONFIG_TRACEPOINT_BENCHMARK) += trace_benchmark.o diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 8115fff17018..7fa2ebc07f60 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -17,6 +17,9 @@ #include <linux/error-injection.h> #include <linux/btf_ids.h> #include <linux/bpf_lsm.h> +#include <linux/fprobe.h> +#include <linux/bsearch.h> +#include <linux/sort.h> #include <net/bpf_sk_storage.h> @@ -77,6 +80,8 @@ u64 bpf_get_stack(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5); static int bpf_btf_printf_prepare(struct btf_ptr *ptr, u32 btf_ptr_size, u64 flags, const struct btf **btf, s32 *btf_id); +static u64 bpf_kprobe_multi_cookie(struct bpf_run_ctx *ctx); +static u64 bpf_kprobe_multi_entry_ip(struct bpf_run_ctx *ctx); /** * trace_call_bpf - invoke BPF program @@ -1032,6 +1037,30 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = { .arg1_type = ARG_PTR_TO_CTX, }; +BPF_CALL_1(bpf_get_func_ip_kprobe_multi, struct pt_regs *, regs) +{ + return bpf_kprobe_multi_entry_ip(current->bpf_ctx); +} + +static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe_multi = { + .func = bpf_get_func_ip_kprobe_multi, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, +}; + +BPF_CALL_1(bpf_get_attach_cookie_kprobe_multi, struct pt_regs *, regs) +{ + return bpf_kprobe_multi_cookie(current->bpf_ctx); +} + +static const struct bpf_func_proto bpf_get_attach_cookie_proto_kmulti = { + .func = bpf_get_attach_cookie_kprobe_multi, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, +}; + BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx) { struct bpf_trace_run_ctx *run_ctx; @@ -1231,6 +1260,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_get_task_stack_proto; case BPF_FUNC_copy_from_user: return prog->aux->sleepable ? &bpf_copy_from_user_proto : NULL; + case BPF_FUNC_copy_from_user_task: + return prog->aux->sleepable ? &bpf_copy_from_user_task_proto : NULL; case BPF_FUNC_snprintf_btf: return &bpf_snprintf_btf_proto; case BPF_FUNC_per_cpu_ptr: @@ -1273,9 +1304,13 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_override_return_proto; #endif case BPF_FUNC_get_func_ip: - return &bpf_get_func_ip_proto_kprobe; + return prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI ? + &bpf_get_func_ip_proto_kprobe_multi : + &bpf_get_func_ip_proto_kprobe; case BPF_FUNC_get_attach_cookie: - return &bpf_get_attach_cookie_proto_trace; + return prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI ? + &bpf_get_attach_cookie_proto_kmulti : + &bpf_get_attach_cookie_proto_trace; default: return bpf_tracing_func_proto(func_id, prog); } @@ -1558,6 +1593,7 @@ static const struct bpf_func_proto bpf_perf_event_output_proto_raw_tp = { extern const struct bpf_func_proto bpf_skb_output_proto; extern const struct bpf_func_proto bpf_xdp_output_proto; +extern const struct bpf_func_proto bpf_xdp_get_buff_len_trace_proto; BPF_CALL_3(bpf_get_stackid_raw_tp, struct bpf_raw_tracepoint_args *, args, struct bpf_map *, map, u64, flags) @@ -1657,6 +1693,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_sock_from_file_proto; case BPF_FUNC_get_socket_cookie: return &bpf_get_socket_ptr_cookie_proto; + case BPF_FUNC_xdp_get_buff_len: + return &bpf_xdp_get_buff_len_trace_proto; #endif case BPF_FUNC_seq_printf: return prog->expected_attach_type == BPF_TRACE_ITER ? @@ -2172,3 +2210,314 @@ static int __init bpf_event_init(void) fs_initcall(bpf_event_init); #endif /* CONFIG_MODULES */ + +#ifdef CONFIG_FPROBE +struct bpf_kprobe_multi_link { + struct bpf_link link; + struct fprobe fp; + unsigned long *addrs; + u64 *cookies; + u32 cnt; +}; + +struct bpf_kprobe_multi_run_ctx { + struct bpf_run_ctx run_ctx; + struct bpf_kprobe_multi_link *link; + unsigned long entry_ip; +}; + +static void bpf_kprobe_multi_link_release(struct bpf_link *link) +{ + struct bpf_kprobe_multi_link *kmulti_link; + + kmulti_link = container_of(link, struct bpf_kprobe_multi_link, link); + unregister_fprobe(&kmulti_link->fp); +} + +static void bpf_kprobe_multi_link_dealloc(struct bpf_link *link) +{ + struct bpf_kprobe_multi_link *kmulti_link; + + kmulti_link = container_of(link, struct bpf_kprobe_multi_link, link); + kvfree(kmulti_link->addrs); + kvfree(kmulti_link->cookies); + kfree(kmulti_link); +} + +static const struct bpf_link_ops bpf_kprobe_multi_link_lops = { + .release = bpf_kprobe_multi_link_release, + .dealloc = bpf_kprobe_multi_link_dealloc, +}; + +static void bpf_kprobe_multi_cookie_swap(void *a, void *b, int size, const void *priv) +{ + const struct bpf_kprobe_multi_link *link = priv; + unsigned long *addr_a = a, *addr_b = b; + u64 *cookie_a, *cookie_b; + unsigned long tmp1; + u64 tmp2; + + cookie_a = link->cookies + (addr_a - link->addrs); + cookie_b = link->cookies + (addr_b - link->addrs); + + /* swap addr_a/addr_b and cookie_a/cookie_b values */ + tmp1 = *addr_a; *addr_a = *addr_b; *addr_b = tmp1; + tmp2 = *cookie_a; *cookie_a = *cookie_b; *cookie_b = tmp2; +} + +static int __bpf_kprobe_multi_cookie_cmp(const void *a, const void *b) +{ + const unsigned long *addr_a = a, *addr_b = b; + + if (*addr_a == *addr_b) + return 0; + return *addr_a < *addr_b ? -1 : 1; +} + +static int bpf_kprobe_multi_cookie_cmp(const void *a, const void *b, const void *priv) +{ + return __bpf_kprobe_multi_cookie_cmp(a, b); +} + +static u64 bpf_kprobe_multi_cookie(struct bpf_run_ctx *ctx) +{ + struct bpf_kprobe_multi_run_ctx *run_ctx; + struct bpf_kprobe_multi_link *link; + u64 *cookie, entry_ip; + unsigned long *addr; + + if (WARN_ON_ONCE(!ctx)) + return 0; + run_ctx = container_of(current->bpf_ctx, struct bpf_kprobe_multi_run_ctx, run_ctx); + link = run_ctx->link; + if (!link->cookies) + return 0; + entry_ip = run_ctx->entry_ip; + addr = bsearch(&entry_ip, link->addrs, link->cnt, sizeof(entry_ip), + __bpf_kprobe_multi_cookie_cmp); + if (!addr) + return 0; + cookie = link->cookies + (addr - link->addrs); + return *cookie; +} + +static u64 bpf_kprobe_multi_entry_ip(struct bpf_run_ctx *ctx) +{ + struct bpf_kprobe_multi_run_ctx *run_ctx; + + run_ctx = container_of(current->bpf_ctx, struct bpf_kprobe_multi_run_ctx, run_ctx); + return run_ctx->entry_ip; +} + +static int +kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link, + unsigned long entry_ip, struct pt_regs *regs) +{ + struct bpf_kprobe_multi_run_ctx run_ctx = { + .link = link, + .entry_ip = entry_ip, + }; + struct bpf_run_ctx *old_run_ctx; + int err; + + if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) { + err = 0; + goto out; + } + + migrate_disable(); + rcu_read_lock(); + old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx); + err = bpf_prog_run(link->link.prog, regs); + bpf_reset_run_ctx(old_run_ctx); + rcu_read_unlock(); + migrate_enable(); + + out: + __this_cpu_dec(bpf_prog_active); + return err; +} + +static void +kprobe_multi_link_handler(struct fprobe *fp, unsigned long entry_ip, + struct pt_regs *regs) +{ + struct bpf_kprobe_multi_link *link; + + link = container_of(fp, struct bpf_kprobe_multi_link, fp); + kprobe_multi_link_prog_run(link, entry_ip, regs); +} + +static int +kprobe_multi_resolve_syms(const void *usyms, u32 cnt, + unsigned long *addrs) +{ + unsigned long addr, size; + const char **syms; + int err = -ENOMEM; + unsigned int i; + char *func; + + size = cnt * sizeof(*syms); + syms = kvzalloc(size, GFP_KERNEL); + if (!syms) + return -ENOMEM; + + func = kmalloc(KSYM_NAME_LEN, GFP_KERNEL); + if (!func) + goto error; + + if (copy_from_user(syms, usyms, size)) { + err = -EFAULT; + goto error; + } + + for (i = 0; i < cnt; i++) { + err = strncpy_from_user(func, syms[i], KSYM_NAME_LEN); + if (err == KSYM_NAME_LEN) + err = -E2BIG; + if (err < 0) + goto error; + err = -EINVAL; + addr = kallsyms_lookup_name(func); + if (!addr) + goto error; + if (!kallsyms_lookup_size_offset(addr, &size, NULL)) + goto error; + addr = ftrace_location_range(addr, addr + size - 1); + if (!addr) + goto error; + addrs[i] = addr; + } + + err = 0; +error: + kvfree(syms); + kfree(func); + return err; +} + +int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) +{ + struct bpf_kprobe_multi_link *link = NULL; + struct bpf_link_primer link_primer; + void __user *ucookies; + unsigned long *addrs; + u32 flags, cnt, size; + void __user *uaddrs; + u64 *cookies = NULL; + void __user *usyms; + int err; + + /* no support for 32bit archs yet */ + if (sizeof(u64) != sizeof(void *)) + return -EOPNOTSUPP; + + if (prog->expected_attach_type != BPF_TRACE_KPROBE_MULTI) + return -EINVAL; + + flags = attr->link_create.kprobe_multi.flags; + if (flags & ~BPF_F_KPROBE_MULTI_RETURN) + return -EINVAL; + + uaddrs = u64_to_user_ptr(attr->link_create.kprobe_multi.addrs); + usyms = u64_to_user_ptr(attr->link_create.kprobe_multi.syms); + if (!!uaddrs == !!usyms) + return -EINVAL; + + cnt = attr->link_create.kprobe_multi.cnt; + if (!cnt) + return -EINVAL; + + size = cnt * sizeof(*addrs); + addrs = kvmalloc(size, GFP_KERNEL); + if (!addrs) + return -ENOMEM; + + if (uaddrs) { + if (copy_from_user(addrs, uaddrs, size)) { + err = -EFAULT; + goto error; + } + } else { + err = kprobe_multi_resolve_syms(usyms, cnt, addrs); + if (err) + goto error; + } + + ucookies = u64_to_user_ptr(attr->link_create.kprobe_multi.cookies); + if (ucookies) { + cookies = kvmalloc(size, GFP_KERNEL); + if (!cookies) { + err = -ENOMEM; + goto error; + } + if (copy_from_user(cookies, ucookies, size)) { + err = -EFAULT; + goto error; + } + } + + link = kzalloc(sizeof(*link), GFP_KERNEL); + if (!link) { + err = -ENOMEM; + goto error; + } + + bpf_link_init(&link->link, BPF_LINK_TYPE_KPROBE_MULTI, + &bpf_kprobe_multi_link_lops, prog); + + err = bpf_link_prime(&link->link, &link_primer); + if (err) + goto error; + + if (flags & BPF_F_KPROBE_MULTI_RETURN) + link->fp.exit_handler = kprobe_multi_link_handler; + else + link->fp.entry_handler = kprobe_multi_link_handler; + + link->addrs = addrs; + link->cookies = cookies; + link->cnt = cnt; + + if (cookies) { + /* + * Sorting addresses will trigger sorting cookies as well + * (check bpf_kprobe_multi_cookie_swap). This way we can + * find cookie based on the address in bpf_get_attach_cookie + * helper. + */ + sort_r(addrs, cnt, sizeof(*addrs), + bpf_kprobe_multi_cookie_cmp, + bpf_kprobe_multi_cookie_swap, + link); + } + + err = register_fprobe_ips(&link->fp, addrs, cnt); + if (err) { + bpf_link_cleanup(&link_primer); + return err; + } + + return bpf_link_settle(&link_primer); + +error: + kfree(link); + kvfree(addrs); + kvfree(cookies); + return err; +} +#else /* !CONFIG_FPROBE */ +int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) +{ + return -EOPNOTSUPP; +} +static u64 bpf_kprobe_multi_cookie(struct bpf_run_ctx *ctx) +{ + return 0; +} +static u64 bpf_kprobe_multi_entry_ip(struct bpf_run_ctx *ctx) +{ + return 0; +} +#endif diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c new file mode 100644 index 000000000000..8b2dd5b9dcd1 --- /dev/null +++ b/kernel/trace/fprobe.c @@ -0,0 +1,332 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fprobe - Simple ftrace probe wrapper for function entry. + */ +#define pr_fmt(fmt) "fprobe: " fmt + +#include <linux/err.h> +#include <linux/fprobe.h> +#include <linux/kallsyms.h> +#include <linux/kprobes.h> +#include <linux/rethook.h> +#include <linux/slab.h> +#include <linux/sort.h> + +#include "trace.h" + +struct fprobe_rethook_node { + struct rethook_node node; + unsigned long entry_ip; +}; + +static void fprobe_handler(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *ops, struct ftrace_regs *fregs) +{ + struct fprobe_rethook_node *fpr; + struct rethook_node *rh; + struct fprobe *fp; + int bit; + + fp = container_of(ops, struct fprobe, ops); + if (fprobe_disabled(fp)) + return; + + bit = ftrace_test_recursion_trylock(ip, parent_ip); + if (bit < 0) { + fp->nmissed++; + return; + } + + if (fp->entry_handler) + fp->entry_handler(fp, ip, ftrace_get_regs(fregs)); + + if (fp->exit_handler) { + rh = rethook_try_get(fp->rethook); + if (!rh) { + fp->nmissed++; + goto out; + } + fpr = container_of(rh, struct fprobe_rethook_node, node); + fpr->entry_ip = ip; + rethook_hook(rh, ftrace_get_regs(fregs), true); + } + +out: + ftrace_test_recursion_unlock(bit); +} +NOKPROBE_SYMBOL(fprobe_handler); + +static void fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *ops, struct ftrace_regs *fregs) +{ + struct fprobe *fp = container_of(ops, struct fprobe, ops); + + if (unlikely(kprobe_running())) { + fp->nmissed++; + return; + } + kprobe_busy_begin(); + fprobe_handler(ip, parent_ip, ops, fregs); + kprobe_busy_end(); +} + +static void fprobe_exit_handler(struct rethook_node *rh, void *data, + struct pt_regs *regs) +{ + struct fprobe *fp = (struct fprobe *)data; + struct fprobe_rethook_node *fpr; + + if (!fp || fprobe_disabled(fp)) + return; + + fpr = container_of(rh, struct fprobe_rethook_node, node); + + fp->exit_handler(fp, fpr->entry_ip, regs); +} +NOKPROBE_SYMBOL(fprobe_exit_handler); + +/* Convert ftrace location address from symbols */ +static unsigned long *get_ftrace_locations(const char **syms, int num) +{ + unsigned long addr, size; + unsigned long *addrs; + int i; + + /* Convert symbols to symbol address */ + addrs = kcalloc(num, sizeof(*addrs), GFP_KERNEL); + if (!addrs) + return ERR_PTR(-ENOMEM); + + for (i = 0; i < num; i++) { + addr = kallsyms_lookup_name(syms[i]); + if (!addr) /* Maybe wrong symbol */ + goto error; + + /* Convert symbol address to ftrace location. */ + if (!kallsyms_lookup_size_offset(addr, &size, NULL) || !size) + goto error; + + addr = ftrace_location_range(addr, addr + size - 1); + if (!addr) /* No dynamic ftrace there. */ + goto error; + + addrs[i] = addr; + } + + return addrs; + +error: + kfree(addrs); + + return ERR_PTR(-ENOENT); +} + +static void fprobe_init(struct fprobe *fp) +{ + fp->nmissed = 0; + if (fprobe_shared_with_kprobes(fp)) + fp->ops.func = fprobe_kprobe_handler; + else + fp->ops.func = fprobe_handler; + fp->ops.flags |= FTRACE_OPS_FL_SAVE_REGS; +} + +static int fprobe_init_rethook(struct fprobe *fp, int num) +{ + int i, size; + + if (num < 0) + return -EINVAL; + + if (!fp->exit_handler) { + fp->rethook = NULL; + return 0; + } + + /* Initialize rethook if needed */ + size = num * num_possible_cpus() * 2; + if (size < 0) + return -E2BIG; + + fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler); + for (i = 0; i < size; i++) { + struct rethook_node *node; + + node = kzalloc(sizeof(struct fprobe_rethook_node), GFP_KERNEL); + if (!node) { + rethook_free(fp->rethook); + fp->rethook = NULL; + return -ENOMEM; + } + rethook_add_node(fp->rethook, node); + } + return 0; +} + +static void fprobe_fail_cleanup(struct fprobe *fp) +{ + if (fp->rethook) { + /* Don't need to cleanup rethook->handler because this is not used. */ + rethook_free(fp->rethook); + fp->rethook = NULL; + } + ftrace_free_filter(&fp->ops); +} + +/** + * register_fprobe() - Register fprobe to ftrace by pattern. + * @fp: A fprobe data structure to be registered. + * @filter: A wildcard pattern of probed symbols. + * @notfilter: A wildcard pattern of NOT probed symbols. + * + * Register @fp to ftrace for enabling the probe on the symbols matched to @filter. + * If @notfilter is not NULL, the symbols matched the @notfilter are not probed. + * + * Return 0 if @fp is registered successfully, -errno if not. + */ +int register_fprobe(struct fprobe *fp, const char *filter, const char *notfilter) +{ + struct ftrace_hash *hash; + unsigned char *str; + int ret, len; + + if (!fp || !filter) + return -EINVAL; + + fprobe_init(fp); + + len = strlen(filter); + str = kstrdup(filter, GFP_KERNEL); + ret = ftrace_set_filter(&fp->ops, str, len, 0); + kfree(str); + if (ret) + return ret; + + if (notfilter) { + len = strlen(notfilter); + str = kstrdup(notfilter, GFP_KERNEL); + ret = ftrace_set_notrace(&fp->ops, str, len, 0); + kfree(str); + if (ret) + goto out; + } + + /* TODO: + * correctly calculate the total number of filtered symbols + * from both filter and notfilter. + */ + hash = fp->ops.local_hash.filter_hash; + if (WARN_ON_ONCE(!hash)) + goto out; + + ret = fprobe_init_rethook(fp, (int)hash->count); + if (!ret) + ret = register_ftrace_function(&fp->ops); + +out: + if (ret) + fprobe_fail_cleanup(fp); + return ret; +} +EXPORT_SYMBOL_GPL(register_fprobe); + +/** + * register_fprobe_ips() - Register fprobe to ftrace by address. + * @fp: A fprobe data structure to be registered. + * @addrs: An array of target ftrace location addresses. + * @num: The number of entries of @addrs. + * + * Register @fp to ftrace for enabling the probe on the address given by @addrs. + * The @addrs must be the addresses of ftrace location address, which may be + * the symbol address + arch-dependent offset. + * If you unsure what this mean, please use other registration functions. + * + * Return 0 if @fp is registered successfully, -errno if not. + */ +int register_fprobe_ips(struct fprobe *fp, unsigned long *addrs, int num) +{ + int ret; + + if (!fp || !addrs || num <= 0) + return -EINVAL; + + fprobe_init(fp); + + ret = ftrace_set_filter_ips(&fp->ops, addrs, num, 0, 0); + if (ret) + return ret; + + ret = fprobe_init_rethook(fp, num); + if (!ret) + ret = register_ftrace_function(&fp->ops); + + if (ret) + fprobe_fail_cleanup(fp); + return ret; +} +EXPORT_SYMBOL_GPL(register_fprobe_ips); + +/** + * register_fprobe_syms() - Register fprobe to ftrace by symbols. + * @fp: A fprobe data structure to be registered. + * @syms: An array of target symbols. + * @num: The number of entries of @syms. + * + * Register @fp to the symbols given by @syms array. This will be useful if + * you are sure the symbols exist in the kernel. + * + * Return 0 if @fp is registered successfully, -errno if not. + */ +int register_fprobe_syms(struct fprobe *fp, const char **syms, int num) +{ + unsigned long *addrs; + int ret; + + if (!fp || !syms || num <= 0) + return -EINVAL; + + addrs = get_ftrace_locations(syms, num); + if (IS_ERR(addrs)) + return PTR_ERR(addrs); + + ret = register_fprobe_ips(fp, addrs, num); + + kfree(addrs); + + return ret; +} +EXPORT_SYMBOL_GPL(register_fprobe_syms); + +/** + * unregister_fprobe() - Unregister fprobe from ftrace + * @fp: A fprobe data structure to be unregistered. + * + * Unregister fprobe (and remove ftrace hooks from the function entries). + * + * Return 0 if @fp is unregistered successfully, -errno if not. + */ +int unregister_fprobe(struct fprobe *fp) +{ + int ret; + + if (!fp || fp->ops.func != fprobe_handler) + return -EINVAL; + + /* + * rethook_free() starts disabling the rethook, but the rethook handlers + * may be running on other processors at this point. To make sure that all + * current running handlers are finished, call unregister_ftrace_function() + * after this. + */ + if (fp->rethook) + rethook_free(fp->rethook); + + ret = unregister_ftrace_function(&fp->ops); + if (ret < 0) + return ret; + + ftrace_free_filter(&fp->ops); + + return ret; +} +EXPORT_SYMBOL_GPL(unregister_fprobe); diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index e59d80c9afd7..2e114659f7f8 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -4958,7 +4958,7 @@ ftrace_notrace_write(struct file *file, const char __user *ubuf, } static int -ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove) +__ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove) { struct ftrace_func_entry *entry; @@ -4977,8 +4977,29 @@ ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove) } static int +ftrace_match_addr(struct ftrace_hash *hash, unsigned long *ips, + unsigned int cnt, int remove) +{ + unsigned int i; + int err; + + for (i = 0; i < cnt; i++) { + err = __ftrace_match_addr(hash, ips[i], remove); + if (err) { + /* + * This expects the @hash is a temporary hash and if this + * fails the caller must free the @hash. + */ + return err; + } + } + return 0; +} + +static int ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len, - unsigned long ip, int remove, int reset, int enable) + unsigned long *ips, unsigned int cnt, + int remove, int reset, int enable) { struct ftrace_hash **orig_hash; struct ftrace_hash *hash; @@ -5008,8 +5029,8 @@ ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len, ret = -EINVAL; goto out_regex_unlock; } - if (ip) { - ret = ftrace_match_addr(hash, ip, remove); + if (ips) { + ret = ftrace_match_addr(hash, ips, cnt, remove); if (ret < 0) goto out_regex_unlock; } @@ -5026,10 +5047,10 @@ ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len, } static int -ftrace_set_addr(struct ftrace_ops *ops, unsigned long ip, int remove, - int reset, int enable) +ftrace_set_addr(struct ftrace_ops *ops, unsigned long *ips, unsigned int cnt, + int remove, int reset, int enable) { - return ftrace_set_hash(ops, NULL, 0, ip, remove, reset, enable); + return ftrace_set_hash(ops, NULL, 0, ips, cnt, remove, reset, enable); } #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS @@ -5634,11 +5655,30 @@ int ftrace_set_filter_ip(struct ftrace_ops *ops, unsigned long ip, int remove, int reset) { ftrace_ops_init(ops); - return ftrace_set_addr(ops, ip, remove, reset, 1); + return ftrace_set_addr(ops, &ip, 1, remove, reset, 1); } EXPORT_SYMBOL_GPL(ftrace_set_filter_ip); /** + * ftrace_set_filter_ips - set functions to filter on in ftrace by addresses + * @ops - the ops to set the filter with + * @ips - the array of addresses to add to or remove from the filter. + * @cnt - the number of addresses in @ips + * @remove - non zero to remove ips from the filter + * @reset - non zero to reset all filters before applying this filter. + * + * Filters denote which functions should be enabled when tracing is enabled + * If @ips array or any ip specified within is NULL , it fails to update filter. + */ +int ftrace_set_filter_ips(struct ftrace_ops *ops, unsigned long *ips, + unsigned int cnt, int remove, int reset) +{ + ftrace_ops_init(ops); + return ftrace_set_addr(ops, ips, cnt, remove, reset, 1); +} +EXPORT_SYMBOL_GPL(ftrace_set_filter_ips); + +/** * ftrace_ops_set_global_filter - setup ops to use global filters * @ops - the ops which will use the global filters * @@ -5659,7 +5699,7 @@ static int ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len, int reset, int enable) { - return ftrace_set_hash(ops, buf, len, 0, 0, reset, enable); + return ftrace_set_hash(ops, buf, len, NULL, 0, 0, reset, enable); } /** diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c new file mode 100644 index 000000000000..ab463a4d2b23 --- /dev/null +++ b/kernel/trace/rethook.c @@ -0,0 +1,317 @@ +// SPDX-License-Identifier: GPL-2.0 + +#define pr_fmt(fmt) "rethook: " fmt + +#include <linux/bug.h> +#include <linux/kallsyms.h> +#include <linux/kprobes.h> +#include <linux/preempt.h> +#include <linux/rethook.h> +#include <linux/slab.h> +#include <linux/sort.h> + +/* Return hook list (shadow stack by list) */ + +/* + * This function is called from delayed_put_task_struct() when a task is + * dead and cleaned up to recycle any kretprobe instances associated with + * this task. These left over instances represent probed functions that + * have been called but will never return. + */ +void rethook_flush_task(struct task_struct *tk) +{ + struct rethook_node *rhn; + struct llist_node *node; + + node = __llist_del_all(&tk->rethooks); + while (node) { + rhn = container_of(node, struct rethook_node, llist); + node = node->next; + preempt_disable(); + rethook_recycle(rhn); + preempt_enable(); + } +} + +static void rethook_free_rcu(struct rcu_head *head) +{ + struct rethook *rh = container_of(head, struct rethook, rcu); + struct rethook_node *rhn; + struct freelist_node *node; + int count = 1; + + node = rh->pool.head; + while (node) { + rhn = container_of(node, struct rethook_node, freelist); + node = node->next; + kfree(rhn); + count++; + } + + /* The rh->ref is the number of pooled node + 1 */ + if (refcount_sub_and_test(count, &rh->ref)) + kfree(rh); +} + +/** + * rethook_free() - Free struct rethook. + * @rh: the struct rethook to be freed. + * + * Free the rethook. Before calling this function, user must ensure the + * @rh::data is cleaned if needed (or, the handler can access it after + * calling this function.) This function will set the @rh to be freed + * after all rethook_node are freed (not soon). And the caller must + * not touch @rh after calling this. + */ +void rethook_free(struct rethook *rh) +{ + rcu_assign_pointer(rh->handler, NULL); + + call_rcu(&rh->rcu, rethook_free_rcu); +} + +/** + * rethook_alloc() - Allocate struct rethook. + * @data: a data to pass the @handler when hooking the return. + * @handler: the return hook callback function. + * + * Allocate and initialize a new rethook with @data and @handler. + * Return NULL if memory allocation fails or @handler is NULL. + * Note that @handler == NULL means this rethook is going to be freed. + */ +struct rethook *rethook_alloc(void *data, rethook_handler_t handler) +{ + struct rethook *rh = kzalloc(sizeof(struct rethook), GFP_KERNEL); + + if (!rh || !handler) + return NULL; + + rh->data = data; + rh->handler = handler; + rh->pool.head = NULL; + refcount_set(&rh->ref, 1); + + return rh; +} + +/** + * rethook_add_node() - Add a new node to the rethook. + * @rh: the struct rethook. + * @node: the struct rethook_node to be added. + * + * Add @node to @rh. User must allocate @node (as a part of user's + * data structure.) The @node fields are initialized in this function. + */ +void rethook_add_node(struct rethook *rh, struct rethook_node *node) +{ + node->rethook = rh; + freelist_add(&node->freelist, &rh->pool); + refcount_inc(&rh->ref); +} + +static void free_rethook_node_rcu(struct rcu_head *head) +{ + struct rethook_node *node = container_of(head, struct rethook_node, rcu); + + if (refcount_dec_and_test(&node->rethook->ref)) + kfree(node->rethook); + kfree(node); +} + +/** + * rethook_recycle() - return the node to rethook. + * @node: The struct rethook_node to be returned. + * + * Return back the @node to @node::rethook. If the @node::rethook is already + * marked as freed, this will free the @node. + */ +void rethook_recycle(struct rethook_node *node) +{ + lockdep_assert_preemption_disabled(); + + if (likely(READ_ONCE(node->rethook->handler))) + freelist_add(&node->freelist, &node->rethook->pool); + else + call_rcu(&node->rcu, free_rethook_node_rcu); +} +NOKPROBE_SYMBOL(rethook_recycle); + +/** + * rethook_try_get() - get an unused rethook node. + * @rh: The struct rethook which pools the nodes. + * + * Get an unused rethook node from @rh. If the node pool is empty, this + * will return NULL. Caller must disable preemption. + */ +struct rethook_node *rethook_try_get(struct rethook *rh) +{ + rethook_handler_t handler = READ_ONCE(rh->handler); + struct freelist_node *fn; + + lockdep_assert_preemption_disabled(); + + /* Check whether @rh is going to be freed. */ + if (unlikely(!handler)) + return NULL; + + fn = freelist_try_get(&rh->pool); + if (!fn) + return NULL; + + return container_of(fn, struct rethook_node, freelist); +} +NOKPROBE_SYMBOL(rethook_try_get); + +/** + * rethook_hook() - Hook the current function return. + * @node: The struct rethook node to hook the function return. + * @regs: The struct pt_regs for the function entry. + * @mcount: True if this is called from mcount(ftrace) context. + * + * Hook the current running function return. This must be called when the + * function entry (or at least @regs must be the registers of the function + * entry.) @mcount is used for identifying the context. If this is called + * from ftrace (mcount) callback, @mcount must be set true. If this is called + * from the real function entry (e.g. kprobes) @mcount must be set false. + * This is because the way to hook the function return depends on the context. + */ +void rethook_hook(struct rethook_node *node, struct pt_regs *regs, bool mcount) +{ + arch_rethook_prepare(node, regs, mcount); + __llist_add(&node->llist, ¤t->rethooks); +} +NOKPROBE_SYMBOL(rethook_hook); + +/* This assumes the 'tsk' is the current task or is not running. */ +static unsigned long __rethook_find_ret_addr(struct task_struct *tsk, + struct llist_node **cur) +{ + struct rethook_node *rh = NULL; + struct llist_node *node = *cur; + + if (!node) + node = tsk->rethooks.first; + else + node = node->next; + + while (node) { + rh = container_of(node, struct rethook_node, llist); + if (rh->ret_addr != (unsigned long)arch_rethook_trampoline) { + *cur = node; + return rh->ret_addr; + } + node = node->next; + } + return 0; +} +NOKPROBE_SYMBOL(__rethook_find_ret_addr); + +/** + * rethook_find_ret_addr -- Find correct return address modified by rethook + * @tsk: Target task + * @frame: A frame pointer + * @cur: a storage of the loop cursor llist_node pointer for next call + * + * Find the correct return address modified by a rethook on @tsk in unsigned + * long type. + * The @tsk must be 'current' or a task which is not running. @frame is a hint + * to get the currect return address - which is compared with the + * rethook::frame field. The @cur is a loop cursor for searching the + * kretprobe return addresses on the @tsk. The '*@cur' should be NULL at the + * first call, but '@cur' itself must NOT NULL. + * + * Returns found address value or zero if not found. + */ +unsigned long rethook_find_ret_addr(struct task_struct *tsk, unsigned long frame, + struct llist_node **cur) +{ + struct rethook_node *rhn = NULL; + unsigned long ret; + + if (WARN_ON_ONCE(!cur)) + return 0; + + if (WARN_ON_ONCE(tsk != current && task_is_running(tsk))) + return 0; + + do { + ret = __rethook_find_ret_addr(tsk, cur); + if (!ret) + break; + rhn = container_of(*cur, struct rethook_node, llist); + } while (rhn->frame != frame); + + return ret; +} +NOKPROBE_SYMBOL(rethook_find_ret_addr); + +void __weak arch_rethook_fixup_return(struct pt_regs *regs, + unsigned long correct_ret_addr) +{ + /* + * Do nothing by default. If the architecture which uses a + * frame pointer to record real return address on the stack, + * it should fill this function to fixup the return address + * so that stacktrace works from the rethook handler. + */ +} + +/* This function will be called from each arch-defined trampoline. */ +unsigned long rethook_trampoline_handler(struct pt_regs *regs, + unsigned long frame) +{ + struct llist_node *first, *node = NULL; + unsigned long correct_ret_addr; + rethook_handler_t handler; + struct rethook_node *rhn; + + correct_ret_addr = __rethook_find_ret_addr(current, &node); + if (!correct_ret_addr) { + pr_err("rethook: Return address not found! Maybe there is a bug in the kernel\n"); + BUG_ON(1); + } + + instruction_pointer_set(regs, correct_ret_addr); + + /* + * These loops must be protected from rethook_free_rcu() because those + * are accessing 'rhn->rethook'. + */ + preempt_disable(); + + /* + * Run the handler on the shadow stack. Do not unlink the list here because + * stackdump inside the handlers needs to decode it. + */ + first = current->rethooks.first; + while (first) { + rhn = container_of(first, struct rethook_node, llist); + if (WARN_ON_ONCE(rhn->frame != frame)) + break; + handler = READ_ONCE(rhn->rethook->handler); + if (handler) + handler(rhn, rhn->rethook->data, regs); + + if (first == node) + break; + first = first->next; + } + + /* Fixup registers for returning to correct address. */ + arch_rethook_fixup_return(regs, correct_ret_addr); + + /* Unlink used shadow stack */ + first = current->rethooks.first; + current->rethooks.first = node->next; + node->next = NULL; + + while (first) { + rhn = container_of(first, struct rethook_node, llist); + first = first->next; + rethook_recycle(rhn); + } + preempt_enable(); + + return correct_ret_addr; +} +NOKPROBE_SYMBOL(rethook_trampoline_handler); |