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authorAlexei Starovoitov <ast@kernel.org>2018-05-21 19:22:30 -0700
committerDavid S. Miller <davem@davemloft.net>2018-05-23 13:23:40 -0400
commitd2ba09c17a0647f899d6c20a11bab9e6d3382f07 (patch)
tree96f528cd9829377165a7357e02438248a88c93b9 /net/Kconfig
parentumh: introduce fork_usermode_blob() helper (diff)
downloadlinux-dev-d2ba09c17a0647f899d6c20a11bab9e6d3382f07.tar.xz
linux-dev-d2ba09c17a0647f899d6c20a11bab9e6d3382f07.zip
net: add skeleton of bpfilter kernel module
bpfilter.ko consists of bpfilter_kern.c (normal kernel module code) and user mode helper code that is embedded into bpfilter.ko The steps to build bpfilter.ko are the following: - main.c is compiled by HOSTCC into the bpfilter_umh elf executable file - with quite a bit of objcopy and Makefile magic the bpfilter_umh elf file is converted into bpfilter_umh.o object file with _binary_net_bpfilter_bpfilter_umh_start and _end symbols Example: $ nm ./bld_x64/net/bpfilter/bpfilter_umh.o 0000000000004cf8 T _binary_net_bpfilter_bpfilter_umh_end 0000000000004cf8 A _binary_net_bpfilter_bpfilter_umh_size 0000000000000000 T _binary_net_bpfilter_bpfilter_umh_start - bpfilter_umh.o and bpfilter_kern.o are linked together into bpfilter.ko bpfilter_kern.c is a normal kernel module code that calls the fork_usermode_blob() helper to execute part of its own data as a user mode process. Notice that _binary_net_bpfilter_bpfilter_umh_start - end is placed into .init.rodata section, so it's freed as soon as __init function of bpfilter.ko is finished. As part of __init the bpfilter.ko does first request/reply action via two unix pipe provided by fork_usermode_blob() helper to make sure that umh is healthy. If not it will kill it via pid. Later bpfilter_process_sockopt() will be called from bpfilter hooks in get/setsockopt() to pass iptable commands into umh via bpfilter.ko If admin does 'rmmod bpfilter' the __exit code bpfilter.ko will kill umh as well. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/Kconfig')
-rw-r--r--net/Kconfig2
1 files changed, 2 insertions, 0 deletions
diff --git a/net/Kconfig b/net/Kconfig
index df8d45ef47d8..ba554cedb615 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -202,6 +202,8 @@ source "net/bridge/netfilter/Kconfig"
endif
+source "net/bpfilter/Kconfig"
+
source "net/dccp/Kconfig"
source "net/sctp/Kconfig"
source "net/rds/Kconfig"