From patchwork Tue Jul 9 00:04:36 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 13727124 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 91F8617C; Tue, 9 Jul 2024 00:04:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720483481; cv=none; b=drQPfYBAq0/rW8nzhmzv/0HH6uGnkqRgDEG5osquAyWRhtT5NlTeS0mtxJ6DVeAtNBNxAiXXC6z7AKwI8DG/lPu3bVaQNc1x6/U9JpVrmJPfmBs89ZG895nDUmMD3hRLvPLdEXMmswdbljTTC7Tr+I0Bo9BefVTfFKD7GK8pXg4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720483481; c=relaxed/simple; bh=qRxTCthB31Syc+yE1yuxaWwHeCheaNQ8QawquA37cTg=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version:Content-Type; b=kEhQRSjCjpbhlJh23Clvsz7qVSzVLvHu+NvAHKTRtQmhprh5iMZ1TW9G/hhmElcDWDSCwhop+UtuQeh9HymQEFJSe0YHNI6sroMGEI4zzw8ovWRHZ4rCYc3S0FCmm+bSzPtcb7RUbSEy38wHO6U18pi17Qsf+YKwlcIMbzLbmlQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PqNQkIse; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="PqNQkIse" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 11DD7C3277B; Tue, 9 Jul 2024 00:04:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1720483481; bh=qRxTCthB31Syc+yE1yuxaWwHeCheaNQ8QawquA37cTg=; h=From:To:Cc:Subject:Date:From; b=PqNQkIsewtM9Zz5i2p0ct3WQFagEz3Cp16Eg505e7DOIQdX10ecpFyZj+tZT7vKTf DsAOufKGqHqZ/3iKwKNLI2nsv9EIF3e2cGg8f/m3c8g5I1fJZ9osEu4fRrdQrD/p+M 4EVA2mqd2ooWPRQgfKhJ2yVsRNDozjzImR/hGGBRhKcgXkJ4uwf9wnlEIAZAMKzFIw 7HIbNsJrhT8H1iMGDWYv2AiwD7EQRZQ3JvDZwU7zW3aRmP7I/ciPx8iAUtk2TUaPY5 Yo1HIwMPN/8puLlpL4modRyWBF28b0TUEfY3mN0/sCp91QwUghGLaJh93aJBz9WehE UXfYKsK/VKVtg== From: "Masami Hiramatsu (Google)" To: LKML , Linux trace kernel Cc: Masami Hiramatsu , Steven Rostedt , Andrii Nakryiko , Francis Laniel , Nikolay Kuratov , bpf@vger.kernel.org Subject: [PATCH for-next v4] tracing/kprobes: Add symbol counting check when module loads Date: Tue, 9 Jul 2024 09:04:36 +0900 Message-Id: <172048347679.185217.9457864992619792356.stgit@devnote2> X-Mailer: git-send-email 2.34.1 User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Masami Hiramatsu (Google) Currently, kprobe event checks whether the target symbol name is unique or not, so that it does not put a probe on an unexpected place. But this skips the check if the target is on a module because the module may not be loaded. To fix this issue, this patch checks the number of probe target symbols in a target module when the module is loaded. If the probe is not on the unique name symbols in the module, it will be rejected at that point. Note that the symbol which has a unique name in the target module, it will be accepted even if there are same-name symbols in the kernel or other modules, Signed-off-by: Masami Hiramatsu (Google) --- Changes in v4: - Hide find_module() in try_module_get_by_name(). - Add bpf ML. Changes in v3: - Update the patch description. - Update for latest probe/for-next Updated from last October post, which was dropped by test failure: https://lore.kernel.org/linux-trace-kernel/169854904604.132316.12500381416261460174.stgit@devnote2/ Changes in v2: - Fix to skip checking uniqueness if the target module is not loaded. - Fix register_module_trace_kprobe() to pass correct symbol name. - Fix to call __register_trace_kprobe() from module callback. --- kernel/trace/trace_kprobe.c | 138 +++++++++++++++++++++++++++++-------------- 1 file changed, 94 insertions(+), 44 deletions(-) diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 7fd0f8576e4c..61a6da808203 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -678,6 +678,21 @@ static int register_trace_kprobe(struct trace_kprobe *tk) } #ifdef CONFIG_MODULES +static int validate_module_probe_symbol(const char *modname, const char *symbol); + +static int register_module_trace_kprobe(struct module *mod, struct trace_kprobe *tk) +{ + const char *p; + int ret = 0; + + p = strchr(trace_kprobe_symbol(tk), ':'); + if (p) + ret = validate_module_probe_symbol(module_name(mod), p + 1); + if (!ret) + ret = __register_trace_kprobe(tk); + return ret; +} + /* Module notifier call back, checking event on the module */ static int trace_kprobe_module_callback(struct notifier_block *nb, unsigned long val, void *data) @@ -696,7 +711,7 @@ static int trace_kprobe_module_callback(struct notifier_block *nb, if (trace_kprobe_within_module(tk, mod)) { /* Don't need to check busy - this should have gone. */ __unregister_trace_kprobe(tk); - ret = __register_trace_kprobe(tk); + ret = register_module_trace_kprobe(mod, tk); if (ret) pr_warn("Failed to re-register probe %s on %s: %d\n", trace_probe_name(&tk->tp), @@ -747,17 +762,81 @@ static int count_mod_symbols(void *data, const char *name, unsigned long unused) return 0; } -static unsigned int number_of_same_symbols(char *func_name) +static unsigned int number_of_same_symbols(const char *mod, const char *func_name) { struct sym_count_ctx ctx = { .count = 0, .name = func_name }; - kallsyms_on_each_match_symbol(count_symbols, func_name, &ctx.count); + if (!mod) + kallsyms_on_each_match_symbol(count_symbols, func_name, &ctx.count); - module_kallsyms_on_each_symbol(NULL, count_mod_symbols, &ctx); + module_kallsyms_on_each_symbol(mod, count_mod_symbols, &ctx); return ctx.count; } +static int validate_module_probe_symbol(const char *modname, const char *symbol) +{ + unsigned int count = number_of_same_symbols(modname, symbol); + + if (count > 1) { + /* + * Users should use ADDR to remove the ambiguity of + * using KSYM only. + */ + return -EADDRNOTAVAIL; + } else if (count == 0) { + /* + * We can return ENOENT earlier than when register the + * kprobe. + */ + return -ENOENT; + } + return 0; +} + +#ifdef CONFIG_MODULES +/* Return NULL if the module is not loaded or under unloading. */ +static struct module *try_module_get_by_name(const char *name) +{ + struct module *mod; + + rcu_read_lock_sched(); + mod = find_module(name); + if (mod && !try_module_get(mod)) + mod = NULL; + rcu_read_unlock_sched(); + + return mod; +} +#else +#define try_module_get_by_name(name) (NULL) +#endif + +static int validate_probe_symbol(char *symbol) +{ + struct module *mod = NULL; + char *modname = NULL, *p; + int ret = 0; + + p = strchr(symbol, ':'); + if (p) { + modname = symbol; + symbol = p + 1; + *p = '\0'; + mod = try_module_get_by_name(modname); + if (!mod) + goto out; + } + + ret = validate_module_probe_symbol(modname, symbol); +out: + if (p) + *p = ':'; + if (mod) + module_put(mod); + return ret; +} + static int trace_kprobe_entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs); @@ -881,6 +960,14 @@ static int __trace_kprobe_create(int argc, const char *argv[]) trace_probe_log_err(0, BAD_PROBE_ADDR); goto parse_error; } + ret = validate_probe_symbol(symbol); + if (ret) { + if (ret == -EADDRNOTAVAIL) + trace_probe_log_err(0, NON_UNIQ_SYMBOL); + else + trace_probe_log_err(0, BAD_PROBE_ADDR); + goto parse_error; + } if (is_return) ctx.flags |= TPARG_FL_RETURN; ret = kprobe_on_func_entry(NULL, symbol, offset); @@ -893,31 +980,6 @@ static int __trace_kprobe_create(int argc, const char *argv[]) } } - if (symbol && !strchr(symbol, ':')) { - unsigned int count; - - count = number_of_same_symbols(symbol); - if (count > 1) { - /* - * Users should use ADDR to remove the ambiguity of - * using KSYM only. - */ - trace_probe_log_err(0, NON_UNIQ_SYMBOL); - ret = -EADDRNOTAVAIL; - - goto error; - } else if (count == 0) { - /* - * We can return ENOENT earlier than when register the - * kprobe. - */ - trace_probe_log_err(0, BAD_PROBE_ADDR); - ret = -ENOENT; - - goto error; - } - } - trace_probe_log_set_index(0); if (event) { ret = traceprobe_parse_event_name(&event, &group, gbuf, @@ -1835,21 +1897,9 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs, char *event; if (func) { - unsigned int count; - - count = number_of_same_symbols(func); - if (count > 1) - /* - * Users should use addr to remove the ambiguity of - * using func only. - */ - return ERR_PTR(-EADDRNOTAVAIL); - else if (count == 0) - /* - * We can return ENOENT earlier than when register the - * kprobe. - */ - return ERR_PTR(-ENOENT); + ret = validate_probe_symbol(func); + if (ret) + return ERR_PTR(ret); } /*