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Commit 8e75887d authored by Masahiro Yamada's avatar Masahiro Yamada Committed by David S. Miller
Browse files

bpfilter: include bpfilter_umh in assembly instead of using objcopy 



What we want here is to embed a user-space program into the kernel.
Instead of the complex ELF magic, let's simply wrap it in the assembly
with the '.incbin' directive.

Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 977c7114

net/bpfilter/Makefile

+2 −15
Original line number Diff line number Diff line
@@ -15,20 +15,7 @@ ifeq ($(CONFIG_BPFILTER_UMH), y) 
HOSTLDFLAGS += -static

endif



# a bit of elf magic to convert bpfilter_umh binary into a binary blob

# inside bpfilter_umh.o elf file referenced by

# _binary_net_bpfilter_bpfilter_umh_start symbol

# which bpfilter_kern.c passes further into umh blob loader at run-time

quiet_cmd_copy_umh = GEN $@

      cmd_copy_umh = echo ':' > $(obj)/.bpfilter_umh.o.cmd; \

      $(OBJCOPY) -I binary \

          `LC_ALL=C $(OBJDUMP) -f net/bpfilter/bpfilter_umh \

          |awk -F' |,' '/file format/{print "-O",$$NF} \

          /^architecture:/{print "-B",$$2}'` \

      --rename-section .data=.init.rodata $< $@



$(obj)/bpfilter_umh.o: $(obj)/bpfilter_umh

	$(call cmd,copy_umh)

$(obj)/bpfilter_umh_blob.o: $(obj)/bpfilter_umh



obj-$(CONFIG_BPFILTER_UMH) += bpfilter.o

bpfilter-objs += bpfilter_kern.o bpfilter_umh.o
 
bpfilter-objs += bpfilter_kern.o bpfilter_umh_blob.o

net/bpfilter/bpfilter_kern.c

+5 −6
Original line number Diff line number Diff line
@@ -10,11 +10,8 @@ 
#include <linux/file.h>

#include "msgfmt.h"



#define UMH_start _binary_net_bpfilter_bpfilter_umh_start

#define UMH_end _binary_net_bpfilter_bpfilter_umh_end



extern char UMH_start;

extern char UMH_end;

extern char bpfilter_umh_start;

extern char bpfilter_umh_end;



static struct umh_info info;

/* since ip_getsockopt() can run in parallel, serialize access to umh */
@@ -93,7 +90,9 @@ static int __init load_umh(void) 
	int err;



	/* fork usermode process */

	err = fork_usermode_blob(&UMH_start, &UMH_end - &UMH_start, &info);

	err = fork_usermode_blob(&bpfilter_umh_start,

				 &bpfilter_umh_end - &bpfilter_umh_start,

				 &info);

	if (err)

		return err;

	pr_info("Loaded bpfilter_umh pid %d\n", info.pid);

net/bpfilter/bpfilter_umh_blob.S

0 → 100644
+7 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

	.section .init.rodata, "a"

	.global bpfilter_umh_start

bpfilter_umh_start:

	.incbin "net/bpfilter/bpfilter_umh"

	.global bpfilter_umh_end

bpfilter_umh_end: