pid_task() dereferences rcu protected tasks array.
But there is no rcu_read_lock() in shutdown_umh() routine so that
rcu_read_lock() is needed.
get_pid_task() is wrapper function of pid_task. it holds rcu_read_lock()
then calls pid_task(). if task isn't NULL, it increases reference count
of task.
test commands:
%modprobe bpfilter
%modprobe -rv bpfilter
splat looks like:
[15102.030932] =============================
[15102.030957] WARNING: suspicious RCU usage
[15102.030985] 4.19.0-rc7+ #21 Not tainted
[15102.031010] -----------------------------
[15102.031038] kernel/pid.c:330 suspicious rcu_dereference_check() usage!
[15102.031063]
other info that might help us debug this:
[15102.031332]
rcu_scheduler_active = 2, debug_locks = 1
[15102.031363] 1 lock held by modprobe/1570:
[15102.031389] #0: 00000000580ef2b0 (bpfilter_lock){+.+.}, at: stop_umh+0x13/0x52 [bpfilter]
[15102.031552]
stack backtrace:
[15102.031583] CPU: 1 PID: 1570 Comm: modprobe Not tainted 4.19.0-rc7+ #21
[15102.031607] Hardware name: To be filled by O.E.M. To be filled by O.E.M./Aptio CRB, BIOS 5.6.5 07/08/2015
[15102.031628] Call Trace:
[15102.031676] dump_stack+0xc9/0x16b
[15102.031723] ? show_regs_print_info+0x5/0x5
[15102.031801] ? lockdep_rcu_suspicious+0x117/0x160
[15102.031855] pid_task+0x134/0x160
[15102.031900] ? find_vpid+0xf0/0xf0
[15102.032017] shutdown_umh.constprop.1+0x1e/0x53 [bpfilter]
[15102.032055] stop_umh+0x46/0x52 [bpfilter]
[15102.032092] __x64_sys_delete_module+0x47e/0x570
[ ... ]
Fixes: d2ba09c17a ("net: add skeleton of bpfilter kernel module")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fixes the following Sparse warnings:
net/bpfilter/bpfilter_kern.c:62:21: warning: cast removes address space
of expression
net/bpfilter/bpfilter_kern.c:101:49: warning: Using plain integer as
NULL pointer
Signed-off-by: Shanthosh RK <shanthosh.rk@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull networking updates from David Miller:
"Highlights:
- Gustavo A. R. Silva keeps working on the implicit switch fallthru
changes.
- Support 802.11ax High-Efficiency wireless in cfg80211 et al, From
Luca Coelho.
- Re-enable ASPM in r8169, from Kai-Heng Feng.
- Add virtual XFRM interfaces, which avoids all of the limitations of
existing IPSEC tunnels. From Steffen Klassert.
- Convert GRO over to use a hash table, so that when we have many
flows active we don't traverse a long list during accumluation.
- Many new self tests for routing, TC, tunnels, etc. Too many
contributors to mention them all, but I'm really happy to keep
seeing this stuff.
- Hardware timestamping support for dpaa_eth/fsl-fman from Yangbo Lu.
- Lots of cleanups and fixes in L2TP code from Guillaume Nault.
- Add IPSEC offload support to netdevsim, from Shannon Nelson.
- Add support for slotting with non-uniform distribution to netem
packet scheduler, from Yousuk Seung.
- Add UDP GSO support to mlx5e, from Boris Pismenny.
- Support offloading of Team LAG in NFP, from John Hurley.
- Allow to configure TX queue selection based upon RX queue, from
Amritha Nambiar.
- Support ethtool ring size configuration in aquantia, from Anton
Mikaev.
- Support DSCP and flowlabel per-transport in SCTP, from Xin Long.
- Support list based batching and stack traversal of SKBs, this is
very exciting work. From Edward Cree.
- Busyloop optimizations in vhost_net, from Toshiaki Makita.
- Introduce the ETF qdisc, which allows time based transmissions. IGB
can offload this in hardware. From Vinicius Costa Gomes.
- Add parameter support to devlink, from Moshe Shemesh.
- Several multiplication and division optimizations for BPF JIT in
nfp driver, from Jiong Wang.
- Lots of prepatory work to make more of the packet scheduler layer
lockless, when possible, from Vlad Buslov.
- Add ACK filter and NAT awareness to sch_cake packet scheduler, from
Toke Høiland-Jørgensen.
- Support regions and region snapshots in devlink, from Alex Vesker.
- Allow to attach XDP programs to both HW and SW at the same time on
a given device, with initial support in nfp. From Jakub Kicinski.
- Add TLS RX offload and support in mlx5, from Ilya Lesokhin.
- Use PHYLIB in r8169 driver, from Heiner Kallweit.
- All sorts of changes to support Spectrum 2 in mlxsw driver, from
Ido Schimmel.
- PTP support in mv88e6xxx DSA driver, from Andrew Lunn.
- Make TCP_USER_TIMEOUT socket option more accurate, from Jon
Maxwell.
- Support for templates in packet scheduler classifier, from Jiri
Pirko.
- IPV6 support in RDS, from Ka-Cheong Poon.
- Native tproxy support in nf_tables, from Máté Eckl.
- Maintain IP fragment queue in an rbtree, but optimize properly for
in-order frags. From Peter Oskolkov.
- Improvde handling of ACKs on hole repairs, from Yuchung Cheng"
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1996 commits)
bpf: test: fix spelling mistake "REUSEEPORT" -> "REUSEPORT"
hv/netvsc: Fix NULL dereference at single queue mode fallback
net: filter: mark expected switch fall-through
xen-netfront: fix warn message as irq device name has '/'
cxgb4: Add new T5 PCI device ids 0x50af and 0x50b0
net: dsa: mv88e6xxx: missing unlock on error path
rds: fix building with IPV6=m
inet/connection_sock: prefer _THIS_IP_ to current_text_addr
net: dsa: mv88e6xxx: bitwise vs logical bug
net: sock_diag: Fix spectre v1 gadget in __sock_diag_cmd()
ieee802154: hwsim: using right kind of iteration
net: hns3: Add vlan filter setting by ethtool command -K
net: hns3: Set tx ring' tc info when netdev is up
net: hns3: Remove tx ring BD len register in hns3_enet
net: hns3: Fix desc num set to default when setting channel
net: hns3: Fix for phy link issue when using marvell phy driver
net: hns3: Fix for information of phydev lost problem when down/up
net: hns3: Fix for command format parsing error in hclge_is_all_function_id_zero
net: hns3: Add support for serdes loopback selftest
bnxt_en: take coredump_record structure off stack
...
In preparation for enabling command line LDFLAGS, re-name HOSTLDFLAGS
to KBUILD_HOSTLDFLAGS as the internal use only flags. This should not
have any visible effects.
Signed-off-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
In preparation for enabling command line CFLAGS, re-name HOSTCFLAGS to
KBUILD_HOSTCFLAGS as the internal use only flags. This should not have
any visible effects.
Signed-off-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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>
With the brand-new syntax extension of Kconfig, we can directly
check the compiler capability in the configuration phase.
If the cc-can-link.sh fails, the BPFILTER_UMH is automatically
hidden by the dependency.
I also deleted 'default n', which is no-op.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Use $(OBJDUMP) instead of literal 'objdump' to avoid
using host toolchain when cross compiling.
Fixes: 421780fd49 ("bpfilter: fix build error")
Signed-off-by: Matteo Croce <mcroce@redhat.com>
Reported-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/bpfilter/bpfilter_umh is a binary file generated when bpfilter is
enabled, add it to .gitignore to avoid committing it.
Fixes: d2ba09c17a ("net: add skeleton of bpfilter kernel module")
Signed-off-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
bpfilter Makefile assumes that the system locale is en_US, and the
parsing of objdump output fails.
Set LC_ALL=C and, while at it, rewrite the objdump parsing so it spawns
only 2 processes instead of 7.
Fixes: d2ba09c17a ("net: add skeleton of bpfilter kernel module")
Signed-off-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
syzbot reported the following crash
[ 338.293946] bpfilter: read fail -512
[ 338.304515] kasan: GPF could be caused by NULL-ptr deref or user memory access
[ 338.311863] general protection fault: 0000 [#1] SMP KASAN
[ 338.344360] RIP: 0010:__vfs_write+0x4a6/0x960
[ 338.426363] Call Trace:
[ 338.456967] __kernel_write+0x10c/0x380
[ 338.460928] __bpfilter_process_sockopt+0x1d8/0x35b
[ 338.487103] bpfilter_mbox_request+0x4d/0xb0
[ 338.491492] bpfilter_ip_get_sockopt+0x6b/0x90
This can happen when multiple cpus trying to talk to user mode process
via bpfilter_mbox_request(). One cpu grabs the mutex while another goes to
sleep on the same mutex. Then former cpu sees that umh pipe is down and
shuts down the pipes. Later cpu finally acquires the mutex and crashes
on freed pipe.
Fix the race by using info.pid as an indicator that umh and pipes are healthy
and check it after acquiring the mutex.
Fixes: d2ba09c17a ("net: add skeleton of bpfilter kernel module")
Reported-by: syzbot+7ade6c94abb2774c0fee@syzkaller.appspotmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
CONFIG_OUTPUT_FORMAT is x86 only macro.
Used objdump to extract elf file format.
Fixes: d2ba09c17a ("net: add skeleton of bpfilter kernel module")
Reported-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
check that CC can build executables and use that compiler instead of HOSTCC
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
gcc-7.3.0 report following err:
HOSTCC net/bpfilter/main.o
In file included from net/bpfilter/main.c:9:0:
./include/uapi/linux/bpf.h:12:10: fatal error: linux/bpf_common.h: No such file or directory
#include <linux/bpf_common.h>
remove it by adding a include path.
Fixes: d2ba09c17a ("net: add skeleton of bpfilter kernel module")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
bpfilter_process_sockopt is a callback that gets called from
ip_setsockopt() and ip_getsockopt(). However, when CONFIG_INET is
disabled, it never gets called at all, and assigning a function to the
callback pointer results in a link failure:
net/bpfilter/bpfilter_kern.o: In function `__stop_umh':
bpfilter_kern.c:(.text.unlikely+0x3): undefined reference to `bpfilter_process_sockopt'
net/bpfilter/bpfilter_kern.o: In function `load_umh':
bpfilter_kern.c:(.init.text+0x73): undefined reference to `bpfilter_process_sockopt'
Since there is no caller in this configuration, I assume we can
simply make the assignment conditional.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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: d2ba09c17a ("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>
BPFILTER could have been enabled without INET causing this build error:
ERROR: "bpfilter_process_sockopt" [net/bpfilter/bpfilter.ko] undefined!
Fixes: d2ba09c17a ("net: add skeleton of bpfilter kernel module")
Reported-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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>
