From mboxrd@z Thu Jan 1 00:00:00 1970 From: Martin KaFai Lau Subject: [PATCH bpf-next v4 06/10] bpf: btf: Add BPF_OBJ_GET_INFO_BY_FD support to BTF fd Date: Tue, 17 Apr 2018 13:42:39 -0700 Message-ID: <20180417204243.4028831-7-kafai@fb.com> References: <20180417204243.4028831-1-kafai@fb.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Alexei Starovoitov , Daniel Borkmann , To: Return-path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:43196 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752757AbeDQUmq (ORCPT ); Tue, 17 Apr 2018 16:42:46 -0400 Received: from pps.filterd (m0109331.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w3HKeO99006095 for ; Tue, 17 Apr 2018 13:42:46 -0700 Received: from mail.thefacebook.com ([199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2hdr5u806j-2 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Tue, 17 Apr 2018 13:42:46 -0700 In-Reply-To: <20180417204243.4028831-1-kafai@fb.com> Sender: netdev-owner@vger.kernel.org List-ID: This patch adds BPF_OBJ_GET_INFO_BY_FD support to BTF fd. The original BTF data, which was used to create the BTF fd during the earlier BPF_BTF_LOAD call, will be returned. The userspace is expected to allocate buffer to info.info and the buffer size is set to info.info_len before calling BPF_OBJ_GET_INFO_BY_FD. The original BTF data is copied to the userspace buffer (info.info). Only upto the user's specified info.info_len will be copied. The original BTF data size is set to info.info_len. The userspace needs to check if it is bigger than its allocated buffer size. If it is, the userspace should realloc with the kernel-returned info.info_len and call the BPF_OBJ_GET_INFO_BY_FD again. Signed-off-by: Martin KaFai Lau Acked-by: Alexei Starovoitov --- include/linux/btf.h | 5 +++++ kernel/bpf/btf.c | 17 ++++++++++++++++- kernel/bpf/syscall.c | 2 ++ 3 files changed, 23 insertions(+), 1 deletion(-) diff --git a/include/linux/btf.h b/include/linux/btf.h index a7c7072535ea..a966dc6d61ee 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -10,9 +10,14 @@ struct btf; struct btf_type; union bpf_attr; +extern const struct file_operations btf_fops; + void btf_put(struct btf *btf); int btf_new_fd(const union bpf_attr *attr); struct btf *btf_get_by_fd(int fd); +int btf_get_info_by_fd(const struct btf *btf, + const union bpf_attr *attr, + union bpf_attr __user *uattr); /* Figure out the size of a type_id. If type_id is a modifier * (e.g. const), it will be resolved to find out the type with size. * diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index ba088f02ed17..b09470d2df91 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -2029,7 +2029,7 @@ static int btf_release(struct inode *inode, struct file *filp) return 0; } -static const struct file_operations btf_fops = { +const struct file_operations btf_fops = { .release = btf_release, }; @@ -2074,3 +2074,18 @@ struct btf *btf_get_by_fd(int fd) return btf; } + +int btf_get_info_by_fd(const struct btf *btf, + const union bpf_attr *attr, + union bpf_attr __user *uattr) +{ + void __user *udata = u64_to_user_ptr(attr->info.info); + u32 copy_len = min_t(u32, btf->data_size, + attr->info.info_len); + + if (copy_to_user(udata, btf->data, copy_len) || + put_user(btf->data_size, &uattr->info.info_len)) + return -EFAULT; + + return 0; +} diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index cd8ebadc66eb..0a4924a0a8da 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2017,6 +2017,8 @@ static int bpf_obj_get_info_by_fd(const union bpf_attr *attr, else if (f.file->f_op == &bpf_map_fops) err = bpf_map_get_info_by_fd(f.file->private_data, attr, uattr); + else if (f.file->f_op == &btf_fops) + err = btf_get_info_by_fd(f.file->private_data, attr, uattr); else err = -EINVAL; -- 2.9.5