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Linux kernel mirror (for testing)
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kernel
os
linux
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: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
authored by
Masahiro Yamada
and committed by
David S. Miller
8e75887d
977c7114
+14
-21
+2
-15
net/bpfilter/Makefile
+2
-15
net/bpfilter/Makefile
···
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HOSTLDFLAGS += -static
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endif
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# a bit of elf magic to convert bpfilter_umh binary into a binary blob
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# inside bpfilter_umh.o elf file referenced by
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# _binary_net_bpfilter_bpfilter_umh_start symbol
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# which bpfilter_kern.c passes further into umh blob loader at run-time
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quiet_cmd_copy_umh = GEN $@
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cmd_copy_umh = echo ':' > $(obj)/.bpfilter_umh.o.cmd; \
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$(OBJCOPY) -I binary \
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`LC_ALL=C $(OBJDUMP) -f net/bpfilter/bpfilter_umh \
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|awk -F' |,' '/file format/{print "-O",$$NF} \
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/^architecture:/{print "-B",$$2}'` \
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--rename-section .data=.init.rodata $< $@
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-
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$(obj)/bpfilter_umh.o: $(obj)/bpfilter_umh
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-
$(call cmd,copy_umh)
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$(obj)/bpfilter_umh_blob.o: $(obj)/bpfilter_umh
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obj-$(CONFIG_BPFILTER_UMH) += bpfilter.o
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bpfilter-objs += bpfilter_kern.o bpfilter_umh.o
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bpfilter-objs += bpfilter_kern.o bpfilter_umh_blob.o
+5
-6
net/bpfilter/bpfilter_kern.c
+5
-6
net/bpfilter/bpfilter_kern.c
···
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#include <linux/file.h>
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#include "msgfmt.h"
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#define UMH_start _binary_net_bpfilter_bpfilter_umh_start
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#define UMH_end _binary_net_bpfilter_bpfilter_umh_end
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-
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extern char UMH_start;
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extern char UMH_end;
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extern char bpfilter_umh_start;
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extern char bpfilter_umh_end;
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static struct umh_info info;
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/* since ip_getsockopt() can run in parallel, serialize access to umh */
···
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int err;
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/* fork usermode process */
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err = fork_usermode_blob(&UMH_start, &UMH_end - &UMH_start, &info);
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err = fork_usermode_blob(&bpfilter_umh_start,
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&bpfilter_umh_end - &bpfilter_umh_start,
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&info);
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if (err)
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return err;
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pr_info("Loaded bpfilter_umh pid %d\n", info.pid);