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The bpfilter UMH code was recently changed to log its informative messages to
/dev/kmsg, however this interface doesn't support SEEK_CUR yet, used by
dprintf(). As result dprintf() returns -EINVAL and doesn't log anything.
However there already had some discussions about supporting SEEK_CUR into
/dev/kmsg interface in the past it wasn't concluded. Since the only user of
that from userspace perspective inside the kernel is the bpfilter UMH
(userspace) module it's better to correct it here instead waiting a conclusion
on the interface.
Fixes: 36c4357c63f3 ("net: bpfilter: print umh messages to /dev/kmsg")
Signed-off-by: Bruno Meneguele <bmeneg@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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bpfilter_umh currently printed all messages to /dev/console and this
might interfere the user activity(*).
This commit changes the output device to /dev/kmsg so that the messages
from bpfilter_umh won't show on the console directly.
(*) https://bugzilla.suse.com/show_bug.cgi?id=1140221
Signed-off-by: Gary Lin <glin@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Currently, the header search paths -Itools/include and
-Itools/include/uapi are not used. Let's drop the unused code.
We can remove -I. too by fixing up one C file.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Passing O_CREAT (00000100) to open means we should also pass file
mode as the third parameter. Creating /dev/console as a regular
file may not be helpful anyway, so simply drop the flag when
opening debug_fd.
Fixes: d2ba09c17a06 ("net: add skeleton of bpfilter kernel module")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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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>
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