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authorMartin KaFai Lau <kafai@fb.com>2018-04-18 15:56:02 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2018-04-19 21:46:25 +0200
commit60197cfb6e11ffc03aa0ed23765b2f7e70b2e2d4 (patch)
treece07ea8aa1bcf4a3c989d8a974a4413a97308c80 /kernel/bpf/btf.c
parentf56a653c1fd13a197076dec4461c656fd2adec73 (diff)
downloadlinux-60197cfb6e11ffc03aa0ed23765b2f7e70b2e2d4.tar.bz2
bpf: btf: Add BPF_OBJ_GET_INFO_BY_FD support to BTF fd
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 <kafai@fb.com> Acked-by: Alexei Starovoitov <ast@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'kernel/bpf/btf.c')
-rw-r--r--kernel/bpf/btf.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 2322340694cf..eb56ac760547 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -2002,7 +2002,7 @@ 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,
};
@@ -2047,3 +2047,18 @@ 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;
+}