From patchwork Wed Apr 14 18:54:01 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florent Revest X-Patchwork-Id: 12203559 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C60C3C433B4 for ; Wed, 14 Apr 2021 18:54:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A4E706124B for ; Wed, 14 Apr 2021 18:54:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346963AbhDNSyl (ORCPT ); Wed, 14 Apr 2021 14:54:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36042 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234717AbhDNSyk (ORCPT ); Wed, 14 Apr 2021 14:54:40 -0400 Received: from mail-wm1-x336.google.com (mail-wm1-x336.google.com [IPv6:2a00:1450:4864:20::336]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 74772C06175F for ; Wed, 14 Apr 2021 11:54:18 -0700 (PDT) Received: by mail-wm1-x336.google.com with SMTP id y124-20020a1c32820000b029010c93864955so13230756wmy.5 for ; Wed, 14 Apr 2021 11:54:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=/yuGjiq19gLSu0QP7DGABe+VXUELpwsjtD6djtldPww=; b=TDqOuunYNxGKv2+HhDKzg5YbinYch5COcqItn+B3Cbl+sgmG7xZCfqK86jI2+ygT68 IQ/q8oyt32x0IaplgUcFCoL078MsK6v4a1zJiRFi1ZO3JVmReLMgkDfvBud87kUFTau7 gYjjIw7ccCHXwwFc3M1fBjR5ga9sRV5QhO33Y= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=/yuGjiq19gLSu0QP7DGABe+VXUELpwsjtD6djtldPww=; b=KmSayHRxQgOJPO6neMYFcaetGDTpj6nnbyGdLqy3pX5glVYW3sHrKk6r06Fs+BNqQP qz5jghHrmbRqIlYwboEwOPKarBzVYtbSaFowDyBBfFnw+5jxcetQWi3mHEPa3FwCuVFF Jnw3dAmBb1PxE0SMmfy2abopExwxtrKoNqtABeTIuOoxq1fB4TTgZ6TGldWpHB+nYVU/ qILDZ72pvHGbEKPpukHUjmGEdOCjEZ5KiFq0tEzhKOE96+OoV6kOlammk9J5Qt4GaiNO kGB6UkjzTklMf2tmNG9jVvPkDv3df/4ydvrEEZWtD6xS55fCLzNrlc3fimodKOclKytr AIxQ== X-Gm-Message-State: AOAM532q9vKCvoQ0AV1XwzguyhR2djU9cwbjsNMFajaX395y3mGBjvF3 IzeK+tp/+rc1Jr3zUig+DzAEndclntm3Dg== X-Google-Smtp-Source: ABdhPJyoIzXd+XSyEqPFdXOJd5nPXp7whYbiNfr8bp2NaeIVLEz9itjsBJVyJa2fTV7Joiq233K27Q== X-Received: by 2002:a1c:44d7:: with SMTP id r206mr4265194wma.172.1618426456503; Wed, 14 Apr 2021 11:54:16 -0700 (PDT) Received: from revest.zrh.corp.google.com ([2a00:79e0:42:204:8b2a:41bd:9d62:10d5]) by smtp.gmail.com with ESMTPSA id f12sm253131wrr.61.2021.04.14.11.54.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Apr 2021 11:54:16 -0700 (PDT) From: Florent Revest To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, yhs@fb.com, kpsingh@kernel.org, jackmanb@chromium.org, linux-kernel@vger.kernel.org, Florent Revest Subject: [PATCH bpf-next v4 1/6] bpf: Factorize bpf_trace_printk and bpf_seq_printf Date: Wed, 14 Apr 2021 20:54:01 +0200 Message-Id: <20210414185406.917890-2-revest@chromium.org> X-Mailer: git-send-email 2.31.1.295.g9ea45b61b8-goog In-Reply-To: <20210414185406.917890-1-revest@chromium.org> References: <20210414185406.917890-1-revest@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Two helpers (trace_printk and seq_printf) have very similar implementations of format string parsing and a third one is coming (snprintf). To avoid code duplication and make the code easier to maintain, this moves the operations associated with format string parsing (validation and argument sanitization) into one generic function. The implementation of the two existing helpers already drifted quite a bit so unifying them entailed a lot of changes: - bpf_trace_printk always expected fmt[fmt_size] to be the terminating NULL character, this is no longer true, the first 0 is terminating. - bpf_trace_printk now supports %% (which produces the percentage char). - bpf_trace_printk now skips width formating fields. - bpf_trace_printk now supports the X modifier (capital hexadecimal). - bpf_trace_printk now supports %pK, %px, %pB, %pi4, %pI4, %pi6 and %pI6 - argument casting on 32 bit has been simplified into one macro and using an enum instead of obscure int increments. - bpf_seq_printf now uses bpf_trace_copy_string instead of strncpy_from_kernel_nofault and handles the %pks %pus specifiers. - bpf_seq_printf now prints longs correctly on 32 bit architectures. - both were changed to use a global per-cpu tmp buffer instead of one stack buffer for trace_printk and 6 small buffers for seq_printf. - to avoid per-cpu buffer usage conflict, these helpers disable preemption while the per-cpu buffer is in use. - both helpers now support the %ps and %pS specifiers to print symbols. The implementation is also moved from bpf_trace.c to helpers.c because the upcoming bpf_snprintf helper will be made available to all BPF programs and will need it. Signed-off-by: Florent Revest --- include/linux/bpf.h | 20 +++ kernel/bpf/helpers.c | 254 +++++++++++++++++++++++++++ kernel/trace/bpf_trace.c | 371 ++++----------------------------------- 3 files changed, 311 insertions(+), 334 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index ff8cd68c01b3..77d1d8c65b81 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2077,4 +2077,24 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, struct btf_id_set; bool btf_id_set_contains(const struct btf_id_set *set, u32 id); +enum bpf_printf_mod_type { + BPF_PRINTF_INT, + BPF_PRINTF_LONG, + BPF_PRINTF_LONG_LONG, +}; + +/* Workaround for getting va_list handling working with different argument type + * combinations generically for 32 and 64 bit archs. + */ +#define BPF_CAST_FMT_ARG(arg_nb, args, mod) \ + (mod[arg_nb] == BPF_PRINTF_LONG_LONG || \ + (mod[arg_nb] == BPF_PRINTF_LONG && __BITS_PER_LONG == 64) \ + ? (u64)args[arg_nb] \ + : (u32)args[arg_nb]) + +int bpf_printf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args, + u64 *final_args, enum bpf_printf_mod_type *mod, + u32 num_args); +void bpf_printf_cleanup(void); + #endif /* _LINUX_BPF_H */ diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index f306611c4ddf..ff427f5b3358 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -669,6 +669,260 @@ const struct bpf_func_proto bpf_this_cpu_ptr_proto = { .arg1_type = ARG_PTR_TO_PERCPU_BTF_ID, }; +static int bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype, + size_t bufsz) +{ + void __user *user_ptr = (__force void __user *)unsafe_ptr; + + buf[0] = 0; + + switch (fmt_ptype) { + case 's': +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE + if ((unsigned long)unsafe_ptr < TASK_SIZE) + return strncpy_from_user_nofault(buf, user_ptr, bufsz); + fallthrough; +#endif + case 'k': + return strncpy_from_kernel_nofault(buf, unsafe_ptr, bufsz); + case 'u': + return strncpy_from_user_nofault(buf, user_ptr, bufsz); + } + + return -EINVAL; +} + +/* Per-cpu temp buffers which can be used by printf-like helpers for %s or %p + */ +#define MAX_PRINTF_BUF_LEN 512 + +struct bpf_printf_buf { + char tmp_buf[MAX_PRINTF_BUF_LEN]; +}; +static DEFINE_PER_CPU(struct bpf_printf_buf, bpf_printf_buf); +static DEFINE_PER_CPU(int, bpf_printf_buf_used); + +static int try_get_fmt_tmp_buf(char **tmp_buf) +{ + struct bpf_printf_buf *bufs; + int used; + + if (*tmp_buf) + return 0; + + preempt_disable(); + used = this_cpu_inc_return(bpf_printf_buf_used); + if (WARN_ON_ONCE(used > 1)) { + this_cpu_dec(bpf_printf_buf_used); + return -EBUSY; + } + bufs = this_cpu_ptr(&bpf_printf_buf); + *tmp_buf = bufs->tmp_buf; + + return 0; +} + +void bpf_printf_cleanup(void) +{ + if (this_cpu_read(bpf_printf_buf_used)) { + this_cpu_dec(bpf_printf_buf_used); + preempt_enable(); + } +} + +/* + * bpf_parse_fmt_str - Generic pass on format strings for printf-like helpers + * + * Returns a negative value if fmt is an invalid format string or 0 otherwise. + * + * This can be used in two ways: + * - Format string verification only: when final_args and mod are NULL + * - Arguments preparation: in addition to the above verification, it writes in + * final_args a copy of raw_args where pointers from BPF have been sanitized + * into pointers safe to use by snprintf. This also writes in the mod array + * the size requirement of each argument, usable by BPF_CAST_FMT_ARG for ex. + * + * In argument preparation mode, if 0 is returned, safe temporary buffers are + * allocated and bpf_printf_cleanup should be called to free them after use. + */ +int bpf_printf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args, + u64 *final_args, enum bpf_printf_mod_type *mod, + u32 num_args) +{ + char *unsafe_ptr = NULL, *tmp_buf = NULL, *fmt_end; + size_t tmp_buf_len = MAX_PRINTF_BUF_LEN; + int err, i, num_spec = 0, copy_size; + enum bpf_printf_mod_type cur_mod; + u64 cur_arg; + char fmt_ptype; + + if (!!final_args != !!mod) + return -EINVAL; + + fmt_end = strnchr(fmt, fmt_size, 0); + if (!fmt_end) + return -EINVAL; + fmt_size = fmt_end - fmt; + + for (i = 0; i < fmt_size; i++) { + if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i])) { + err = -EINVAL; + goto out; + } + + if (fmt[i] != '%') + continue; + + if (fmt[i + 1] == '%') { + i++; + continue; + } + + if (num_spec >= num_args) { + err = -EINVAL; + goto out; + } + + /* The string is zero-terminated so if fmt[i] != 0, we can + * always access fmt[i + 1], in the worst case it will be a 0 + */ + i++; + + /* skip optional "[0 +-][num]" width formatting field */ + while (fmt[i] == '0' || fmt[i] == '+' || fmt[i] == '-' || + fmt[i] == ' ') + i++; + if (fmt[i] >= '1' && fmt[i] <= '9') { + i++; + while (fmt[i] >= '0' && fmt[i] <= '9') + i++; + } + + if (fmt[i] == 'p') { + cur_mod = BPF_PRINTF_LONG; + + if ((fmt[i + 1] == 'k' || fmt[i + 1] == 'u') && + fmt[i + 2] == 's') { + fmt_ptype = fmt[i + 1]; + i += 2; + goto fmt_str; + } + + if (fmt[i + 1] == 0 || isspace(fmt[i + 1]) || + ispunct(fmt[i + 1]) || fmt[i + 1] == 'K' || + fmt[i + 1] == 'x' || fmt[i + 1] == 'B' || + fmt[i + 1] == 's' || fmt[i + 1] == 'S') { + /* just kernel pointers */ + if (final_args) + cur_arg = raw_args[num_spec]; + goto fmt_next; + } + + /* only support "%pI4", "%pi4", "%pI6" and "%pi6". */ + if ((fmt[i + 1] != 'i' && fmt[i + 1] != 'I') || + (fmt[i + 2] != '4' && fmt[i + 2] != '6')) { + err = -EINVAL; + goto out; + } + + i += 2; + if (!final_args) + goto fmt_next; + + if (try_get_fmt_tmp_buf(&tmp_buf)) { + err = -EBUSY; + goto out; + } + + copy_size = (fmt[i + 2] == '4') ? 4 : 16; + if (tmp_buf_len < copy_size) { + err = -ENOSPC; + goto out; + } + + unsafe_ptr = (char *)(long)raw_args[num_spec]; + err = copy_from_kernel_nofault(tmp_buf, unsafe_ptr, + copy_size); + if (err < 0) + memset(tmp_buf, 0, copy_size); + cur_arg = (u64)(long)tmp_buf; + tmp_buf += copy_size; + tmp_buf_len -= copy_size; + + goto fmt_next; + } else if (fmt[i] == 's') { + cur_mod = BPF_PRINTF_LONG; + fmt_ptype = fmt[i]; +fmt_str: + if (fmt[i + 1] != 0 && + !isspace(fmt[i + 1]) && + !ispunct(fmt[i + 1])) { + err = -EINVAL; + goto out; + } + + if (!final_args) + goto fmt_next; + + if (try_get_fmt_tmp_buf(&tmp_buf)) { + err = -EBUSY; + goto out; + } + + if (!tmp_buf_len) { + err = -ENOSPC; + goto out; + } + + unsafe_ptr = (char *)(long)raw_args[num_spec]; + err = bpf_trace_copy_string(tmp_buf, unsafe_ptr, + fmt_ptype, tmp_buf_len); + if (err < 0) { + tmp_buf[0] = '\0'; + err = 1; + } + + cur_arg = (u64)(long)tmp_buf; + tmp_buf += err; + tmp_buf_len -= err; + + goto fmt_next; + } + + cur_mod = BPF_PRINTF_INT; + + if (fmt[i] == 'l') { + cur_mod = BPF_PRINTF_LONG; + i++; + } + if (fmt[i] == 'l') { + cur_mod = BPF_PRINTF_LONG_LONG; + i++; + } + + if (fmt[i] != 'i' && fmt[i] != 'd' && fmt[i] != 'u' && + fmt[i] != 'x' && fmt[i] != 'X') { + err = -EINVAL; + goto out; + } + + if (final_args) + cur_arg = raw_args[num_spec]; +fmt_next: + if (final_args) { + mod[num_spec] = cur_mod; + final_args[num_spec] = cur_arg; + } + num_spec++; + } + + err = 0; +out: + if (err) + bpf_printf_cleanup(); + return err; +} + const struct bpf_func_proto bpf_get_current_task_proto __weak; const struct bpf_func_proto bpf_probe_read_user_proto __weak; const struct bpf_func_proto bpf_probe_read_user_str_proto __weak; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 0d23755c2747..a13f8644b357 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -372,188 +372,38 @@ static const struct bpf_func_proto *bpf_get_probe_write_proto(void) return &bpf_probe_write_user_proto; } -static void bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype, - size_t bufsz) -{ - void __user *user_ptr = (__force void __user *)unsafe_ptr; - - buf[0] = 0; - - switch (fmt_ptype) { - case 's': -#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE - if ((unsigned long)unsafe_ptr < TASK_SIZE) { - strncpy_from_user_nofault(buf, user_ptr, bufsz); - break; - } - fallthrough; -#endif - case 'k': - strncpy_from_kernel_nofault(buf, unsafe_ptr, bufsz); - break; - case 'u': - strncpy_from_user_nofault(buf, user_ptr, bufsz); - break; - } -} - static DEFINE_RAW_SPINLOCK(trace_printk_lock); -#define BPF_TRACE_PRINTK_SIZE 1024 +#define MAX_TRACE_PRINTK_VARARGS 3 +#define BPF_TRACE_PRINTK_SIZE 1024 -static __printf(1, 0) int bpf_do_trace_printk(const char *fmt, ...) +BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1, + u64, arg2, u64, arg3) { + u64 args[MAX_TRACE_PRINTK_VARARGS] = { arg1, arg2, arg3 }; + enum bpf_printf_mod_type mod[MAX_TRACE_PRINTK_VARARGS]; static char buf[BPF_TRACE_PRINTK_SIZE]; unsigned long flags; - va_list ap; int ret; - raw_spin_lock_irqsave(&trace_printk_lock, flags); - va_start(ap, fmt); - ret = vsnprintf(buf, sizeof(buf), fmt, ap); - va_end(ap); - /* vsnprintf() will not append null for zero-length strings */ + ret = bpf_printf_prepare(fmt, fmt_size, args, args, mod, + MAX_TRACE_PRINTK_VARARGS); + if (ret < 0) + return ret; + + ret = snprintf(buf, sizeof(buf), fmt, BPF_CAST_FMT_ARG(0, args, mod), + BPF_CAST_FMT_ARG(1, args, mod), BPF_CAST_FMT_ARG(2, args, mod)); + /* snprintf() will not append null for zero-length strings */ if (ret == 0) buf[0] = '\0'; + + raw_spin_lock_irqsave(&trace_printk_lock, flags); trace_bpf_trace_printk(buf); raw_spin_unlock_irqrestore(&trace_printk_lock, flags); - return ret; -} - -/* - * Only limited trace_printk() conversion specifiers allowed: - * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %pB %pks %pus %s - */ -BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1, - u64, arg2, u64, arg3) -{ - int i, mod[3] = {}, fmt_cnt = 0; - char buf[64], fmt_ptype; - void *unsafe_ptr = NULL; - bool str_seen = false; + bpf_printf_cleanup(); - /* - * bpf_check()->check_func_arg()->check_stack_boundary() - * guarantees that fmt points to bpf program stack, - * fmt_size bytes of it were initialized and fmt_size > 0 - */ - if (fmt[--fmt_size] != 0) - return -EINVAL; - - /* check format string for allowed specifiers */ - for (i = 0; i < fmt_size; i++) { - if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i])) - return -EINVAL; - - if (fmt[i] != '%') - continue; - - if (fmt_cnt >= 3) - return -EINVAL; - - /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */ - i++; - if (fmt[i] == 'l') { - mod[fmt_cnt]++; - i++; - } else if (fmt[i] == 'p') { - mod[fmt_cnt]++; - if ((fmt[i + 1] == 'k' || - fmt[i + 1] == 'u') && - fmt[i + 2] == 's') { - fmt_ptype = fmt[i + 1]; - i += 2; - goto fmt_str; - } - - if (fmt[i + 1] == 'B') { - i++; - goto fmt_next; - } - - /* disallow any further format extensions */ - if (fmt[i + 1] != 0 && - !isspace(fmt[i + 1]) && - !ispunct(fmt[i + 1])) - return -EINVAL; - - goto fmt_next; - } else if (fmt[i] == 's') { - mod[fmt_cnt]++; - fmt_ptype = fmt[i]; -fmt_str: - if (str_seen) - /* allow only one '%s' per fmt string */ - return -EINVAL; - str_seen = true; - - if (fmt[i + 1] != 0 && - !isspace(fmt[i + 1]) && - !ispunct(fmt[i + 1])) - return -EINVAL; - - switch (fmt_cnt) { - case 0: - unsafe_ptr = (void *)(long)arg1; - arg1 = (long)buf; - break; - case 1: - unsafe_ptr = (void *)(long)arg2; - arg2 = (long)buf; - break; - case 2: - unsafe_ptr = (void *)(long)arg3; - arg3 = (long)buf; - break; - } - - bpf_trace_copy_string(buf, unsafe_ptr, fmt_ptype, - sizeof(buf)); - goto fmt_next; - } - - if (fmt[i] == 'l') { - mod[fmt_cnt]++; - i++; - } - - if (fmt[i] != 'i' && fmt[i] != 'd' && - fmt[i] != 'u' && fmt[i] != 'x') - return -EINVAL; -fmt_next: - fmt_cnt++; - } - -/* Horrid workaround for getting va_list handling working with different - * argument type combinations generically for 32 and 64 bit archs. - */ -#define __BPF_TP_EMIT() __BPF_ARG3_TP() -#define __BPF_TP(...) \ - bpf_do_trace_printk(fmt, ##__VA_ARGS__) - -#define __BPF_ARG1_TP(...) \ - ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64)) \ - ? __BPF_TP(arg1, ##__VA_ARGS__) \ - : ((mod[0] == 1 || (mod[0] == 0 && __BITS_PER_LONG == 32)) \ - ? __BPF_TP((long)arg1, ##__VA_ARGS__) \ - : __BPF_TP((u32)arg1, ##__VA_ARGS__))) - -#define __BPF_ARG2_TP(...) \ - ((mod[1] == 2 || (mod[1] == 1 && __BITS_PER_LONG == 64)) \ - ? __BPF_ARG1_TP(arg2, ##__VA_ARGS__) \ - : ((mod[1] == 1 || (mod[1] == 0 && __BITS_PER_LONG == 32)) \ - ? __BPF_ARG1_TP((long)arg2, ##__VA_ARGS__) \ - : __BPF_ARG1_TP((u32)arg2, ##__VA_ARGS__))) - -#define __BPF_ARG3_TP(...) \ - ((mod[2] == 2 || (mod[2] == 1 && __BITS_PER_LONG == 64)) \ - ? __BPF_ARG2_TP(arg3, ##__VA_ARGS__) \ - : ((mod[2] == 1 || (mod[2] == 0 && __BITS_PER_LONG == 32)) \ - ? __BPF_ARG2_TP((long)arg3, ##__VA_ARGS__) \ - : __BPF_ARG2_TP((u32)arg3, ##__VA_ARGS__))) - - return __BPF_TP_EMIT(); + return ret; } static const struct bpf_func_proto bpf_trace_printk_proto = { @@ -581,184 +431,37 @@ const struct bpf_func_proto *bpf_get_trace_printk_proto(void) } #define MAX_SEQ_PRINTF_VARARGS 12 -#define MAX_SEQ_PRINTF_MAX_MEMCPY 6 -#define MAX_SEQ_PRINTF_STR_LEN 128 - -struct bpf_seq_printf_buf { - char buf[MAX_SEQ_PRINTF_MAX_MEMCPY][MAX_SEQ_PRINTF_STR_LEN]; -}; -static DEFINE_PER_CPU(struct bpf_seq_printf_buf, bpf_seq_printf_buf); -static DEFINE_PER_CPU(int, bpf_seq_printf_buf_used); BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size, const void *, data, u32, data_len) { - int err = -EINVAL, fmt_cnt = 0, memcpy_cnt = 0; - int i, buf_used, copy_size, num_args; - u64 params[MAX_SEQ_PRINTF_VARARGS]; - struct bpf_seq_printf_buf *bufs; - const u64 *args = data; - - buf_used = this_cpu_inc_return(bpf_seq_printf_buf_used); - if (WARN_ON_ONCE(buf_used > 1)) { - err = -EBUSY; - goto out; - } - - bufs = this_cpu_ptr(&bpf_seq_printf_buf); - - /* - * bpf_check()->check_func_arg()->check_stack_boundary() - * guarantees that fmt points to bpf program stack, - * fmt_size bytes of it were initialized and fmt_size > 0 - */ - if (fmt[--fmt_size] != 0) - goto out; - - if (data_len & 7) - goto out; - - for (i = 0; i < fmt_size; i++) { - if (fmt[i] == '%') { - if (fmt[i + 1] == '%') - i++; - else if (!data || !data_len) - goto out; - } - } + enum bpf_printf_mod_type mod[MAX_SEQ_PRINTF_VARARGS]; + u64 args[MAX_SEQ_PRINTF_VARARGS]; + int err, num_args; + if (data_len & 7 || data_len > MAX_SEQ_PRINTF_VARARGS * 8 || + (data_len && !data)) + return -EINVAL; num_args = data_len / 8; - /* check format string for allowed specifiers */ - for (i = 0; i < fmt_size; i++) { - /* only printable ascii for now. */ - if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i])) { - err = -EINVAL; - goto out; - } - - if (fmt[i] != '%') - continue; - - if (fmt[i + 1] == '%') { - i++; - continue; - } - - if (fmt_cnt >= MAX_SEQ_PRINTF_VARARGS) { - err = -E2BIG; - goto out; - } - - if (fmt_cnt >= num_args) { - err = -EINVAL; - goto out; - } - - /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */ - i++; - - /* skip optional "[0 +-][num]" width formating field */ - while (fmt[i] == '0' || fmt[i] == '+' || fmt[i] == '-' || - fmt[i] == ' ') - i++; - if (fmt[i] >= '1' && fmt[i] <= '9') { - i++; - while (fmt[i] >= '0' && fmt[i] <= '9') - i++; - } - - if (fmt[i] == 's') { - void *unsafe_ptr; - - /* try our best to copy */ - if (memcpy_cnt >= MAX_SEQ_PRINTF_MAX_MEMCPY) { - err = -E2BIG; - goto out; - } - - unsafe_ptr = (void *)(long)args[fmt_cnt]; - err = strncpy_from_kernel_nofault(bufs->buf[memcpy_cnt], - unsafe_ptr, MAX_SEQ_PRINTF_STR_LEN); - if (err < 0) - bufs->buf[memcpy_cnt][0] = '\0'; - params[fmt_cnt] = (u64)(long)bufs->buf[memcpy_cnt]; - - fmt_cnt++; - memcpy_cnt++; - continue; - } - - if (fmt[i] == 'p') { - if (fmt[i + 1] == 0 || - fmt[i + 1] == 'K' || - fmt[i + 1] == 'x' || - fmt[i + 1] == 'B') { - /* just kernel pointers */ - params[fmt_cnt] = args[fmt_cnt]; - fmt_cnt++; - continue; - } - - /* only support "%pI4", "%pi4", "%pI6" and "%pi6". */ - if (fmt[i + 1] != 'i' && fmt[i + 1] != 'I') { - err = -EINVAL; - goto out; - } - if (fmt[i + 2] != '4' && fmt[i + 2] != '6') { - err = -EINVAL; - goto out; - } - - if (memcpy_cnt >= MAX_SEQ_PRINTF_MAX_MEMCPY) { - err = -E2BIG; - goto out; - } - - - copy_size = (fmt[i + 2] == '4') ? 4 : 16; - - err = copy_from_kernel_nofault(bufs->buf[memcpy_cnt], - (void *) (long) args[fmt_cnt], - copy_size); - if (err < 0) - memset(bufs->buf[memcpy_cnt], 0, copy_size); - params[fmt_cnt] = (u64)(long)bufs->buf[memcpy_cnt]; - - i += 2; - fmt_cnt++; - memcpy_cnt++; - continue; - } - - if (fmt[i] == 'l') { - i++; - if (fmt[i] == 'l') - i++; - } - - if (fmt[i] != 'i' && fmt[i] != 'd' && - fmt[i] != 'u' && fmt[i] != 'x' && - fmt[i] != 'X') { - err = -EINVAL; - goto out; - } - - params[fmt_cnt] = args[fmt_cnt]; - fmt_cnt++; - } + err = bpf_printf_prepare(fmt, fmt_size, data, args, mod, num_args); + if (err < 0) + return err; /* Maximumly we can have MAX_SEQ_PRINTF_VARARGS parameter, just give * all of them to seq_printf(). */ - seq_printf(m, fmt, params[0], params[1], params[2], params[3], - params[4], params[5], params[6], params[7], params[8], - params[9], params[10], params[11]); + seq_printf(m, fmt, BPF_CAST_FMT_ARG(0, args, mod), + BPF_CAST_FMT_ARG(1, args, mod), BPF_CAST_FMT_ARG(2, args, mod), + BPF_CAST_FMT_ARG(3, args, mod), BPF_CAST_FMT_ARG(4, args, mod), + BPF_CAST_FMT_ARG(5, args, mod), BPF_CAST_FMT_ARG(6, args, mod), + BPF_CAST_FMT_ARG(7, args, mod), BPF_CAST_FMT_ARG(8, args, mod), + BPF_CAST_FMT_ARG(9, args, mod), BPF_CAST_FMT_ARG(10, args, mod), + BPF_CAST_FMT_ARG(11, args, mod)); - err = seq_has_overflowed(m) ? -EOVERFLOW : 0; -out: - this_cpu_dec(bpf_seq_printf_buf_used); - return err; + bpf_printf_cleanup(); + + return seq_has_overflowed(m) ? -EOVERFLOW : 0; } BTF_ID_LIST_SINGLE(btf_seq_file_ids, struct, seq_file)