From patchwork Sun Aug 18 00:23:49 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jordan Rome X-Patchwork-Id: 13767326 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mout.perfora.net (mout.perfora.net [74.208.4.197]) (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 333992114 for ; Sun, 18 Aug 2024 00:24:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.208.4.197 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723940665; cv=none; b=ZIJw5DqVkekjI1ChH9DCPr/1p4ilt/oDwI9XJH7BxsK0o6EOLM6bMjdQWLO9Rr+sU+QnqgQS6MJvTgg+lDm7xBWBDsgblV2Y30t1T0WyvrOBuVgLMCPjVLQBwNmRNupqMpyXCuYtmdqSPlzu7ttVAoiz2bOtDFrBomCSQ4Ic8lY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723940665; c=relaxed/simple; bh=ShxksYbpLzfJt7S8euOlAPZ5q3IgwP/qHTlYGJr5M2o=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=V7WaaKA1T4/v2bhASs28oQoWaCc6FsElX/065OsuC67iUgd366nqgctyN5E996ih8aV2JNCnjMKKXPFSdHpE7acQPJpU22rLYjabXP3He/U6odfWAv9Zk8L9HZ+opRPnq6KMjQqe0RAGzpax97Apycu4s1m0cTOz3VMqL8HOyRs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=jordanrome.com; spf=pass smtp.mailfrom=jordanrome.com; dkim=pass (2048-bit key) header.d=jordanrome.com header.i=linux@jordanrome.com header.b=LXde8Cg1; arc=none smtp.client-ip=74.208.4.197 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=jordanrome.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=jordanrome.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=jordanrome.com header.i=linux@jordanrome.com header.b="LXde8Cg1" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=jordanrome.com; s=s1-ionos; t=1723940635; x=1724545435; i=linux@jordanrome.com; bh=jMcq+Ar+oIvdGv95hROfzm5z7JJXBUtmeqMH6/jZFc0=; h=X-UI-Sender-Class:From:To:Cc:Subject:Date:Message-ID: MIME-Version:Content-Transfer-Encoding:cc: content-transfer-encoding:content-type:date:from:message-id: mime-version:reply-to:subject:to; b=LXde8Cg1ZAlVkKXmmijFe9fPJ1//AMuj9xO9hlFd/pS2uAeo82sLM/p9uQMuCzxA hBcCypKgkpf7/DsUtc/q3Y8BokOkJEECZpoM0b9DSbT839uxfNX3JkHSPIWmSQCZg t630YPK13uzwO4XQDDGgRwgPqfJearCsbS1+NnYM1dMDur1us8R+UueRAX4kb8jgK 5DDn10hG03ZHSMiSaCotmQkkKyfRQ2EwwBmXYJCuLkPkHEV+pHaknV+e+MO6Y1FWd uDK0ihFCZuctauKPM+lz1s2ZsmY+14NvY6SUsugqKl4MAdu+2W3oDdra1+sSukrcG PAUkXZqGbR1+xeCAWQ== X-UI-Sender-Class: 55c96926-9e95-11ee-ae09-1f7a4046a0f6 Received: from localhost ([173.252.127.12]) by mrelay.perfora.net (mreueus002 [74.208.5.2]) with ESMTPSA (Nemesis) id 0LjYZq-1s8brf0DHs-00eLSn; Sun, 18 Aug 2024 02:23:55 +0200 From: Jordan Rome To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Kernel Team , sinquersw@gmail.com Subject: [bpf-next v6 1/2] bpf: Add bpf_copy_from_user_str kfunc Date: Sat, 17 Aug 2024 17:23:49 -0700 Message-ID: <20240818002350.1401842-1-linux@jordanrome.com> X-Mailer: git-send-email 2.43.5 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Provags-ID: V03:K1:6lQics20wU+u6qx79PlyzCjedjmD7yJoFaYmYSSqj2QwfG+BbHW cYcmUYhTQM8zOZj/gxwSg/0hraPvU+A3TEhqnHewh2zaK2HdlRsQVIGwo7Emaw0ywpdpHwq fG0hJbmH4DCMNi4i9pec4SWfVhtqa69DM//17uHEIFUuldI/CdamGGh+DPe9BT59VUM2G0C K4Y5+4PD691OWufQw6UTQ== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:2l139Fq+31w=;HbP8IcL7li0NK3HYtTWsZMZKt8H jifCrYz47a+mNoO34zc+0S92pSMlcUs3KD51oyFn9v/WPRNDsoyoqPiRR2F6k0pUOvJFCG+q7 8/xiVQ2NQLDdaRdOGXoxedvHNt9rhhlsaJZA8hBFAbcDgSflS5WI0xE6yCm1lAJuRIK5M4kGr i9WnkaP+GDh9Z0asxiwACG2S1PuxDY5qEewOhYQgiEtUg6LJdvWUtHeckiaPdiqFg4btoTogd BZbkZaB9BXNsfHrj6ts0Lo2oP4EWv0xe2gHuEoUL3KXYR8CIUuFVaKY6y2p723zgbDcJuwovB LC1d5Pfc1lEABj+Epf44gSDNKm0WrXg6ctGYcFex4n5A3niJFD7V9xBHpugm1XLvYh+2Haeg2 NyYliLADZD0R3EkI6CrzaHUSTEqmjjx4kcXFBO1MRLl7jDsaLg4nXvYRPhkS7YUDjMpJtNA9D 1gYrp/lJsNtRioFEc9noJ42+SCBn5/C3Q0pqwGzXFVSpVT5XN3k49PlpXR/xjOkZ38+smJkP8 nALEfurrj+M+mIaLO4nwdEsLUocLrI3iv0CMgFwzQdQt9xRguWuw8kBs5V9e3OzKtXSfnWmmb JRVAxrMnERrKlcbeeijW6ZDzzydctbfbvfSw9ZgoVJFJRy5tG/ohbzbfAYTr45ApXkfwqae/d X5nfOSxdw8FXLu2ccI6SqK3BNO+E7kSyM/tIacTeGiFRE43VAwthI2SGpm/n556ou3mgi2Lft RRNIclKkIKq+bdG0c5P0KcnKaDcE2dEQA== X-Patchwork-Delegate: bpf@iogearbox.net This adds a kfunc wrapper around strncpy_from_user, which can be called from sleepable BPF programs. This matches the non-sleepable 'bpf_probe_read_user_str' helper except it includes an additional 'flags' param, which allows consumers to clear the entire destination buffer on success. Signed-off-by: Jordan Rome Acked-by: Andrii Nakryiko --- include/uapi/linux/bpf.h | 8 +++++++ kernel/bpf/helpers.c | 44 ++++++++++++++++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 8 +++++++ 3 files changed, 60 insertions(+) -- 2.43.5 diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index e05b39e39c3f..5e6be3489e43 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -7513,4 +7513,12 @@ struct bpf_iter_num { __u64 __opaque[1]; } __attribute__((aligned(8))); +/* + * Flags to control bpf_copy_from_user_str() behaviour. + * - BPF_F_PAD_ZEROS: Memset 0 the tail of the destination buffer on success + */ +enum { + BPF_F_PAD_ZEROS = (1ULL << 0) +}; + #endif /* _UAPI__LINUX_BPF_H__ */ diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index d02ae323996b..a0d2cc8f4f3f 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2939,6 +2939,49 @@ __bpf_kfunc void bpf_iter_bits_destroy(struct bpf_iter_bits *it) bpf_mem_free(&bpf_global_ma, kit->bits); } +/** + * bpf_copy_from_user_str() - Copy a string from an unsafe user address + * @dst: Destination address, in kernel space. This buffer must be at + * least @dst__szk bytes long. + * @dst__szk: Maximum number of bytes to copy, including the trailing NUL. + * @unsafe_ptr__ign: Source address, in user space. + * @flags: The only supported flag is BPF_F_PAD_ZEROS + * + * Copies a NUL-terminated string from userspace to BPF space. If user string is + * too long this will still ensure zero termination in the dst buffer unless + * buffer size is 0. + * + * If BPF_F_PAD_ZEROS flag is set, memset the tail of @dst to 0 on success and + * memset all of @dst on failure. + */ +__bpf_kfunc int bpf_copy_from_user_str(void *dst, u32 dst__szk, const void __user *unsafe_ptr__ign, u64 flags) +{ + int ret; + + if (unlikely(!dst__szk)) + return 0; + + if (unlikely(flags & ~BPF_F_PAD_ZEROS)) + return -EINVAL; + + ret = strncpy_from_user(dst, unsafe_ptr__ign, dst__szk - 1); + if (ret < 0) { + if (flags & BPF_F_PAD_ZEROS) + memset((char *)dst, 0, dst__szk); + + return ret; + } + + if (flags & BPF_F_PAD_ZEROS) + memset((char *)dst + ret, 0, dst__szk - ret); + else + ((char *)dst)[ret] = '\0'; + + ret++; + + return ret; +} + __bpf_kfunc_end_defs(); BTF_KFUNCS_START(generic_btf_ids) @@ -3024,6 +3067,7 @@ BTF_ID_FLAGS(func, bpf_preempt_enable) BTF_ID_FLAGS(func, bpf_iter_bits_new, KF_ITER_NEW) BTF_ID_FLAGS(func, bpf_iter_bits_next, KF_ITER_NEXT | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_iter_bits_destroy, KF_ITER_DESTROY) +BTF_ID_FLAGS(func, bpf_copy_from_user_str, KF_SLEEPABLE) BTF_KFUNCS_END(common_btf_ids) static const struct btf_kfunc_id_set common_kfunc_set = { diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index e05b39e39c3f..a8dcb99ed904 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -7513,4 +7513,12 @@ struct bpf_iter_num { __u64 __opaque[1]; } __attribute__((aligned(8))); +/* + * Flags to control bpf_copy_from_user_str() behaviour. + * - BPF_F_PAD_ZEROS: Memset 0 the entire destination buffer on success + */ +enum { + BPF_F_PAD_ZEROS = (1ULL << 0) +}; + #endif /* _UAPI__LINUX_BPF_H__ */