From patchwork Fri Nov 3 19:01:39 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 13444924 X-Patchwork-Delegate: bpf@iogearbox.net 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 C373811730; Fri, 3 Nov 2023 19:01:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="E1HXFhi0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 77AFBC433C7; Fri, 3 Nov 2023 19:01:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699038119; bh=4XDOFWKpdyUxrnkPy12hq1XQGgAcPE3Gkf8AWwErQpc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E1HXFhi0HD081HDvzpc7LNZD1a07AdWy4PEz1K40IrfmO59k9PZ6d3XoO/7W/6Q8U iQ+oVirkUJQuYrVW0GHjowA6lbFeaDjPMl95P/FOfixTSay5HEyFkWMGR9RymDg7Ye Nvfmje0ktMsOsIggzL7f5yopWyTi0w4s1qqu7vvAcj7aZJ77VOwUTm2V13u+l0/uwr LKpkJnEl2GBrIA7/7uShcAJ5pFCoYZUdl5CwEmkYvd8b8upWq2hd3T3sEY+Jbmhp7V mdP1ALMkibF0ylZEGkKi54ruZdRHDDaplr5Ju6WhbDNYkZlC0F495itFBN5tjp+3xZ nrtcuHj5eHeAA== From: Song Liu To: bpf@vger.kernel.org, fsverity@lists.linux.dev Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@kernel.org, kernel-team@meta.com, ebiggers@kernel.org, tytso@mit.edu, roberto.sassu@huaweicloud.com, kpsingh@kernel.org, vadfed@meta.com, Song Liu Subject: [PATCH v9 bpf-next 1/9] bpf: Add __bpf_dynptr_data* for in kernel use Date: Fri, 3 Nov 2023 12:01:39 -0700 Message-Id: <20231103190147.1757520-2-song@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231103190147.1757520-1-song@kernel.org> References: <20231103190147.1757520-1-song@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net Different types of bpf dynptr have different internal data storage. Specifically, SKB and XDP type of dynptr may have non-continuous data. Therefore, it is not always safe to directly access dynptr->data. Add __bpf_dynptr_data and __bpf_dynptr_data_rw to replace direct access to dynptr->data. Update bpf_verify_pkcs7_signature to use __bpf_dynptr_data instead of dynptr->data. Signed-off-by: Song Liu --- include/linux/bpf.h | 2 ++ kernel/bpf/helpers.c | 47 ++++++++++++++++++++++++++++++++++++++++ kernel/trace/bpf_trace.c | 10 +++++---- 3 files changed, 55 insertions(+), 4 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index b4825d3cdb29..129c5a7c5982 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1222,6 +1222,8 @@ enum bpf_dynptr_type { int bpf_dynptr_check_size(u32 size); u32 __bpf_dynptr_size(const struct bpf_dynptr_kern *ptr); +void *__bpf_dynptr_data(const struct bpf_dynptr_kern *ptr, u32 len); +void *__bpf_dynptr_data_rw(const struct bpf_dynptr_kern *ptr, u32 len); #ifdef CONFIG_BPF_JIT int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr); diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index e46ac288a108..ddd1a5a81652 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2611,3 +2611,50 @@ static int __init kfunc_init(void) } late_initcall(kfunc_init); + +/* Get a pointer to dynptr data up to len bytes for read only access. If + * the dynptr doesn't have continuous data up to len bytes, return NULL. + */ +void *__bpf_dynptr_data(const struct bpf_dynptr_kern *ptr, u32 len) +{ + enum bpf_dynptr_type type; + int err; + + if (!ptr->data) + return NULL; + + err = bpf_dynptr_check_off_len(ptr, 0, len); + if (err) + return NULL; + type = bpf_dynptr_get_type(ptr); + + switch (type) { + case BPF_DYNPTR_TYPE_LOCAL: + case BPF_DYNPTR_TYPE_RINGBUF: + return ptr->data + ptr->offset; + case BPF_DYNPTR_TYPE_SKB: + return skb_pointer_if_linear(ptr->data, ptr->offset, len); + case BPF_DYNPTR_TYPE_XDP: + { + void *xdp_ptr = bpf_xdp_pointer(ptr->data, ptr->offset, len); + + if (IS_ERR_OR_NULL(xdp_ptr)) + return NULL; + return xdp_ptr; + } + default: + WARN_ONCE(true, "unknown dynptr type %d\n", type); + return NULL; + } +} + +/* Get a pointer to dynptr data up to len bytes for read write access. If + * the dynptr doesn't have continuous data up to len bytes, or the dynptr + * is read only, return NULL. + */ +void *__bpf_dynptr_data_rw(const struct bpf_dynptr_kern *ptr, u32 len) +{ + if (__bpf_dynptr_is_rdonly(ptr)) + return NULL; + return __bpf_dynptr_data(ptr, len); +} diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index df697c74d519..bfe6fb83e8d0 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1378,6 +1378,7 @@ __bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr, struct bpf_dynptr_kern *sig_ptr, struct bpf_key *trusted_keyring) { + void *data, *sig; int ret; if (trusted_keyring->has_ref) { @@ -1394,10 +1395,11 @@ __bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr, return ret; } - return verify_pkcs7_signature(data_ptr->data, - __bpf_dynptr_size(data_ptr), - sig_ptr->data, - __bpf_dynptr_size(sig_ptr), + data = __bpf_dynptr_data(data_ptr, __bpf_dynptr_size(data_ptr)); + sig = __bpf_dynptr_data(sig_ptr, __bpf_dynptr_size(sig_ptr)); + + return verify_pkcs7_signature(data, __bpf_dynptr_size(data_ptr), + sig, __bpf_dynptr_size(sig_ptr), trusted_keyring->key, VERIFYING_UNSPECIFIED_SIGNATURE, NULL, NULL);