From mboxrd@z Thu Jan 1 00:00:00 1970 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 38F0112E1CC for ; Mon, 26 Feb 2024 18:00:21 +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=1708970422; cv=none; b=pO9VXEHIVEB/1oGermJCCb9gIHefMJD4UhD/oiW5je2AlnJNYnMY87p4aQFH0zsEm+mKLezXRVCgCW7iklfnewjzzwTbvo/UO/rzrj2AkbHJNe1YjdxAiFfBqVuPtVXVLPVCg59aZDS9yXGTXTqjgG8a4CtTGfyDJAQRMuJlGPY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708970422; c=relaxed/simple; bh=3cgWbsILfFUsLgfMhtdxKybF9L7xscWnZzCJILBs2xk=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=ci8ULAWThudFrJDl9uA+4O4L2tb005TWuHTOTv9WWvVaxnnXre+EoiezR/5o+6YhFSB2aC2ezRBNDZvpwHj/ybIwW9ejUu9cjFqmuLshG4NNV0R7VYTS7qObEuQ9sEpa2m7wVoFcGWGsLemRTcUjczaJ8XbcZcfhnRN/hnWAxZM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=umcXnLPr; 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="umcXnLPr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C1CDC433F1; Mon, 26 Feb 2024 18:00:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708970421; bh=3cgWbsILfFUsLgfMhtdxKybF9L7xscWnZzCJILBs2xk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=umcXnLPrOCif7IFHdjK3WlpRUmIjqxuMvZvPTHsTVdfx1IhUCMBQ2O9wFfZhuZ6dR 9jnq7I0vQrsTCwADHaLVVibNTBtmdUblNXxMhSlBGatjThwWxUlwnsGUOuCOj1KFX9 Zp6mDEESS5EtFRX0AgD+89j76M42r4bncrQTBHCL/mRCjO/etTavBkKTkWNF4X0cvY nyk3czMFa1slAXznyfb+4t4FcIh6RLC+h/l7tf6ez7bMZz+9j9LTrVntF3+u4VKgXt kNer/kCgxehA1qcXYuzP/xGgLodIqAaGaUKhgt3GeX8CMjCh70xcszytaS8vG1CPNd 3Srqynog6kxtg== Date: Mon, 26 Feb 2024 10:00:20 -0800 From: Jakub Kicinski To: Donald Hunter Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, jiri@resnulli.us, sdf@google.com, nicolas.dichtel@6wind.com Subject: Re: [PATCH net-next 00/15] tools: ynl: stop using libmnl Message-ID: <20240226100020.2aa27e8f@kernel.org> In-Reply-To: References: <20240222235614.180876-1-kuba@kernel.org> <20240223083440.0793cd46@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 26 Feb 2024 09:04:12 +0000 Donald Hunter wrote: > > On Fri, 23 Feb 2024 16:26:33 +0000 Donald Hunter wrote: > >> Is the absence of buffer bounds checking intentional, i.e. relying on libasan? > > > > In ynl.c or the generated code? > > I'm looking at ynl_attr_nest_start() and ynl_attr_put*() in ynl-priv.h > and there's no checks for buffer overrun. It is admittedly a big > buffer, with rx following tx, but still. You're right. But this series isn't making it worse, AFAIU. We weren't checking before, we aren't checking now. I don't want to have to add another arg to all put() calls. How about we sash the max len on nlmsg_pid? Something like: diff --git a/tools/net/ynl/lib/ynl-priv.h b/tools/net/ynl/lib/ynl-priv.h index 6361318e5c4c..d4ffe18b00f9 100644 --- a/tools/net/ynl/lib/ynl-priv.h +++ b/tools/net/ynl/lib/ynl-priv.h @@ -135,6 +135,8 @@ int ynl_error_parse(struct ynl_parse_arg *yarg, const char *msg); /* Netlink message handling helpers */ +#define YNL_MSG_OVERFLOW 1 + static inline struct nlmsghdr *ynl_nlmsg_put_header(void *buf) { struct nlmsghdr *nlh = buf; @@ -239,11 +241,26 @@ ynl_attr_first(const void *start, size_t len, size_t skip) return ynl_attr_if_good(start + len, attr); } +static inline bool +__ynl_attr_put_overflow(struct nlmsghdr *nlh, size_t size) +{ + bool o; + + /* We stash buffer length on nlmsg_pid. */ + o = nlh->nlmsg_len + NLA_HDRLEN + NLMSG_ALIGN(size) > nlh->nlmsg_pid; + if (o) + nlh->nlmsg_pid = YNL_MSG_OVERFLOW; + return o; +} + static inline struct nlattr * ynl_attr_nest_start(struct nlmsghdr *nlh, unsigned int attr_type) { struct nlattr *attr; + if (__ynl_attr_put_overflow(nlh, 0)) + return ynl_nlmsg_end_addr(nlh) - NLA_HDRLEN; + attr = ynl_nlmsg_end_addr(nlh); attr->nla_type = attr_type | NLA_F_NESTED; nlh->nlmsg_len += NLMSG_ALIGN(sizeof(struct nlattr)); @@ -263,6 +280,9 @@ ynl_attr_put(struct nlmsghdr *nlh, unsigned int attr_type, { struct nlattr *attr; + if (__ynl_attr_put_overflow(nlh, size)) + return; + attr = ynl_nlmsg_end_addr(nlh); attr->nla_type = attr_type; attr->nla_len = NLA_HDRLEN + size; @@ -276,14 +296,17 @@ static inline void ynl_attr_put_str(struct nlmsghdr *nlh, unsigned int attr_type, const char *str) { struct nlattr *attr; - const char *end; + size_t len; + + len = strlen(str); + if (__ynl_attr_put_overflow(nlh, len)) + return; attr = ynl_nlmsg_end_addr(nlh); attr->nla_type = attr_type; - end = stpcpy(ynl_attr_data(attr), str); - attr->nla_len = - NLA_HDRLEN + NLA_ALIGN(end - (char *)ynl_attr_data(attr)); + strcpy(ynl_attr_data(attr), str); + attr->nla_len = NLA_HDRLEN + NLA_ALIGN(len); nlh->nlmsg_len += NLMSG_ALIGN(attr->nla_len); } diff --git a/tools/net/ynl/lib/ynl.c b/tools/net/ynl/lib/ynl.c index 86729119e1ef..c2ba72f68028 100644 --- a/tools/net/ynl/lib/ynl.c +++ b/tools/net/ynl/lib/ynl.c @@ -404,9 +404,33 @@ struct nlmsghdr *ynl_msg_start(struct ynl_sock *ys, __u32 id, __u16 flags) nlh->nlmsg_flags = flags; nlh->nlmsg_seq = ++ys->seq; + /* This is a local YNL hack for length checking, we put the buffer + * length in nlmsg_pid, since messages sent to the kernel always use + * PID 0. Message needs to be terminated with ynl_msg_end(). + */ + nlh->nlmsg_pid = YNL_SOCKET_BUFFER_SIZE; + return nlh; } +static int ynl_msg_end(struct ynl_sock *ys, struct nlmsghdr *nlh) +{ + /* We stash buffer length on nlmsg_pid */ + if (nlh->nlmsg_pid == 0) { + yerr(ys, YNL_ERROR_INPUT_INVALID, + "Unknwon input buffer lenght"); + return -EINVAL; + } + if (nlh->nlmsg_pid == YNL_MSG_OVERFLOW) { + yerr(ys, YNL_ERROR_INPUT_TOO_BIG, + "Constructred message longer than internal buffer"); + return -EMSGSIZE; + } + + nlh->nlmsg_pid = 0; + return 0; +} + struct nlmsghdr * ynl_gemsg_start(struct ynl_sock *ys, __u32 id, __u16 flags, __u8 cmd, __u8 version) @@ -606,6 +630,10 @@ static int ynl_sock_read_family(struct ynl_sock *ys, const char *family_name) nlh = ynl_gemsg_start_req(ys, GENL_ID_CTRL, CTRL_CMD_GETFAMILY, 1); ynl_attr_put_str(nlh, CTRL_ATTR_FAMILY_NAME, family_name); + err = ynl_msg_end(ys, nlh); + if (err < 0) + return err; + err = send(ys->socket, nlh, nlh->nlmsg_len, 0); if (err < 0) { perr(ys, "failed to request socket family info"); @@ -867,6 +895,10 @@ int ynl_exec(struct ynl_sock *ys, struct nlmsghdr *req_nlh, { int err; + err = ynl_msg_end(ys, req_nlh); + if (err < 0) + return err; + err = send(ys->socket, req_nlh, req_nlh->nlmsg_len, 0); if (err < 0) return err; @@ -920,6 +952,10 @@ int ynl_exec_dump(struct ynl_sock *ys, struct nlmsghdr *req_nlh, { int err; + err = ynl_msg_end(ys, req_nlh); + if (err < 0) + return err; + err = send(ys->socket, req_nlh, req_nlh->nlmsg_len, 0); if (err < 0) return err; diff --git a/tools/net/ynl/lib/ynl.h b/tools/net/ynl/lib/ynl.h index dbeeef8ce91a..9842e85a8c57 100644 --- a/tools/net/ynl/lib/ynl.h +++ b/tools/net/ynl/lib/ynl.h @@ -20,6 +20,8 @@ enum ynl_error_code { YNL_ERROR_ATTR_INVALID, YNL_ERROR_UNKNOWN_NTF, YNL_ERROR_INV_RESP, + YNL_ERROR_INPUT_INVALID, + YNL_ERROR_INPUT_TOO_BIG, }; /** -- 2.43.2