Re: [PATCH v2] kheaders: Move from proc to sysfs

On Sat, May 4, 2019 at 9:26 PM Joel Fernandes (Google) joel@joelfernandes.org wrote:

The kheaders archive consisting of the kernel headers used for compiling bpf programs is in /proc. However there is concern that moving it here will make it permanent. Let us move it to /sys/kernel as discussed [1].

[1] https://lore.kernel.org/patchwork/patch/1067310/#1265969

Suggested-by: Steven Rostedt rostedt@goodmis.org Signed-off-by: Joel Fernandes (Google) joel@joelfernandes.org

---

This patch applies on top of the previous patch that was applied to the driver tree: https://lore.kernel.org/patchwork/patch/1067310/

v1->v2: Fixed some kconfig nits (Masami).

My name is Masahiro, just in case.

init/Kconfig | 16 ++++----- kernel/Makefile | 4 +-- kernel/{gen_ikh_data.sh => gen_kheaders.sh} | 2 +- kernel/kheaders.c | 40 +++++++++------------ 4 files changed, 26 insertions(+), 36 deletions(-) rename kernel/{gen_ikh_data.sh => gen_kheaders.sh} (98%)

diff --git a/init/Kconfig b/init/Kconfig index 26a364a95b57..c3661991b089 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -579,15 +579,13 @@ config IKCONFIG_PROC This option enables access to the kernel configuration file through /proc/config.gz.

-config IKHEADERS_PROC

•   tristate "Enable kernel header artifacts through /proc/kheaders.tar.xz"
  

•   depends on PROC_FS
  

•   help
  

•     This option enables access to the kernel header and other artifacts that
  

•     are generated during the build process. These can be used to build eBPF
  

•     tracing programs, or similar programs.  If you build the headers as a
  

•     module, a module called kheaders.ko is built which can be loaded on-demand
  

•     to get access to the headers.
  

+config IKHEADERS

•   tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
  

In v1, I suggested to change "depends on PROC_FS" to "depends on SYSFS".

fs/sysfs/ must be compiled to make this feature work.

•   help
  

•     This option enables access to the in-kernel headers that are generated during
  

•     the build process. These can be used to build eBPF tracing programs,
  

•     or similar programs.  If you build the headers as a module, a module called
  

While you are touching the help, could you make the number of spaces between sentences consistent?

Thanks.

•     kheaders.ko is built which can be loaded on-demand to get access to headers.
  
  

config LOG_BUF_SHIFT int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" diff --git a/kernel/Makefile b/kernel/Makefile index 12399614c350..b32a558fae2f 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -70,7 +70,7 @@ obj-$(CONFIG_UTS_NS) += utsname.o obj-$(CONFIG_USER_NS) += user_namespace.o obj-$(CONFIG_PID_NS) += pid_namespace.o obj-$(CONFIG_IKCONFIG) += configs.o -obj-$(CONFIG_IKHEADERS_PROC) += kheaders.o +obj-$(CONFIG_IKHEADERS) += kheaders.o obj-$(CONFIG_SMP) += stop_machine.o obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o obj-$(CONFIG_AUDIT) += audit.o auditfilter.o @@ -126,7 +126,7 @@ $(obj)/config_data.gz: $(KCONFIG_CONFIG) FORCE $(obj)/kheaders.o: $(obj)/kheaders_data.tar.xz

quiet_cmd_genikh = CHK $(obj)/kheaders_data.tar.xz -cmd_genikh = $(srctree)/kernel/gen_ikh_data.sh $@ +cmd_genikh = $(srctree)/kernel/gen_kheaders.sh $@ $(obj)/kheaders_data.tar.xz: FORCE $(call cmd,genikh)

diff --git a/kernel/gen_ikh_data.sh b/kernel/gen_kheaders.sh similarity index 98% rename from kernel/gen_ikh_data.sh rename to kernel/gen_kheaders.sh index 591a94f7b387..581b83534587 100755 --- a/kernel/gen_ikh_data.sh +++ b/kernel/gen_kheaders.sh @@ -2,7 +2,7 @@ # SPDX-License-Identifier: GPL-2.0

# This script generates an archive consisting of kernel headers -# for CONFIG_IKHEADERS_PROC. +# for CONFIG_IKHEADERS. set -e spath="$(dirname "$(readlink -f "$0")")" kroot="$spath/.." diff --git a/kernel/kheaders.c b/kernel/kheaders.c index 70ae6052920d..6a16f8f6898d 100644 --- a/kernel/kheaders.c +++ b/kernel/kheaders.c @@ -8,9 +8,8 @@

#include <linux/kernel.h> #include <linux/module.h> -#include <linux/proc_fs.h> +#include <linux/kobject.h> #include <linux/init.h> -#include <linux/uaccess.h>

/*

• Define kernel_headers_data and kernel_headers_data_end, within which the

@@ -31,39 +30,32 @@ extern char kernel_headers_data; extern char kernel_headers_data_end;

static ssize_t -ikheaders_read_current(struct file *file, char __user *buf,

•                 size_t len, loff_t *offset)
  

+ikheaders_read(struct file *file, struct kobject *kobj,

•          struct bin_attribute *bin_attr,
  

•          char *buf, loff_t off, size_t len)
  

{

•   return simple_read_from_buffer(buf, len, offset,
  

•                                  &kernel_headers_data,
  

•                                  &kernel_headers_data_end -
  

•                                  &kernel_headers_data);
  

•   memcpy(buf, &kernel_headers_data + off, len);
  

•   return len;
  

}

-static const struct file_operations ikheaders_file_ops = {

•   .read = ikheaders_read_current,
  

•   .llseek = default_llseek,
  

+static struct bin_attribute kheaders_attr __ro_after_init = {

•   .attr = {
  

•           .name = "kheaders.tar.xz",
  

•           .mode = S_IRUGO,
  

•   },
  

•   .read = &ikheaders_read,
  

};

static int __init ikheaders_init(void) {

•   struct proc_dir_entry *entry;
  

•   /* create the current headers file */
  

•   entry = proc_create("kheaders.tar.xz", S_IRUGO, NULL,
  

•                       &ikheaders_file_ops);
  

•   if (!entry)
  

•           return -ENOMEM;
  

•   proc_set_size(entry,
  

•                 &kernel_headers_data_end -
  

•                 &kernel_headers_data);
  

•   return 0;
  

•   kheaders_attr.size = (&kernel_headers_data_end -
  

•                         &kernel_headers_data);
  

•   return sysfs_create_bin_file(kernel_kobj, &kheaders_attr);
  

}

static void __exit ikheaders_cleanup(void) {

•   remove_proc_entry("kheaders.tar.xz", NULL);
  

•   sysfs_remove_bin_file(kernel_kobj, &kheaders_attr);
  

}

module_init(ikheaders_init);

2.21.0.1020.gf2820cf01a-goog

-- Best Regards

Masahiro Yamada