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  1. May 10, 2019
  3. May 07, 2019
    • Christian Brauner's avatar
      samples: show race-free pidfd metadata access · 43c6afee
      Christian Brauner authored 
      
This is a sample program showing userspace how to get race-free access
to process metadata from a pidfd.  It is rather easy to do and userspace
can actually simply reuse code that currently parses a process's status
file in procfs.
The program can easily be extended into a generic helper suitable for
inclusion in a libc to make it even easier for userspace to gain metadata
access.

Since this came up in a discussion because this API is going to be used
in various service managers: A lot of programs will have a whitelist
seccomp filter that returns <some-errno> for all new syscalls.  This
means that programs might get confused if CLONE_PIDFD works but the
later pidfd_send_signal() syscall doesn't.  Hence, here's a ahead of
time check that pidfd_send_signal() is supported:

bool pidfd_send_signal_supported()
{
        int procfd = open("/proc/self", O_DIRECTORY | O_RDONLY | O_CLOEXEC);
        if (procfd < 0)
                return false;

        /*
         * A process is always allowed to signal itself so
         * pidfd_send_signal() should never fail this test. If it does
         * it must mean it is not available, blocked by an LSM, seccomp,
         * or other.
         */
        return pidfd_send_signal(procfd, 0, NULL, 0) == 0;
}

Signed-off-by: default avatarChristian Brauner <christian@brauner.io>
Co-developed-by: default avatarJann Horn <jannh@google.com>
Signed-off-by: default avatarJann Horn <jannh@google.com>
Reviewed-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: David Howells <dhowells@redhat.com>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
      43c6afee
  5. May 03, 2019
  7. Apr 25, 2019
  9. Apr 05, 2019
    • Alexei Starovoitov's avatar
      samples/bpf: fix build with new clang · 636e78b1
      Alexei Starovoitov authored 
      
clang started to error on invalid asm clobber usage in x86 headers
and many bpf program samples failed to build with the message:

  CLANG-bpf  /data/users/ast/bpf-next/samples/bpf/xdp_redirect_kern.o
In file included from /data/users/ast/bpf-next/samples/bpf/xdp_redirect_kern.c:14:
In file included from ../include/linux/in.h:23:
In file included from ../include/uapi/linux/in.h:24:
In file included from ../include/linux/socket.h:8:
In file included from ../include/linux/uio.h:14:
In file included from ../include/crypto/hash.h:16:
In file included from ../include/linux/crypto.h:26:
In file included from ../include/linux/uaccess.h:5:
In file included from ../include/linux/sched.h:15:
In file included from ../include/linux/sem.h:5:
In file included from ../include/uapi/linux/sem.h:5:
In file included from ../include/linux/ipc.h:9:
In file included from ../include/linux/refcount.h:72:
../arch/x86/include/asm/refcount.h:72:36: error: asm-specifier for input or output variable conflicts with asm clobber list
                                         r->refs.counter, e, "er", i, "cx");
                                                                      ^
../arch/x86/include/asm/refcount.h:86:27: error: asm-specifier for input or output variable conflicts with asm clobber list
                                         r->refs.counter, e, "cx");
                                                             ^
2 errors generated.

Override volatile() to workaround the problem.

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      636e78b1
  11. Apr 04, 2019
  13. Mar 27, 2019
  15. Mar 22, 2019
  17. Mar 20, 2019
  19. Mar 08, 2019
  21. Mar 07, 2019
  23. Mar 02, 2019
    • brakmo's avatar
      bpf: HBM test script · 4ffd44cf
      brakmo authored 
      
Script for testing HBM (Host Bandwidth Manager) framework.
It creates a cgroup to use for testing and load a BPF program to limit
egress bandwidht. It then uses iperf3 or netperf to create
loads. The output is the goodput in Mbps (unless -D is used).

It can work on a single host using loopback or among two hosts (with netperf).
When using loopback, it is recommended to also introduce a delay of at least
1ms (-d=1), otherwise the assigned bandwidth is likely to be underutilized.

USAGE: $name [out] [-b=<prog>|--bpf=<prog>] [-c=<cc>|--cc=<cc>] [-D]
             [-d=<delay>|--delay=<delay>] [--debug] [-E]
             [-f=<#flows>|--flows=<#flows>] [-h] [-i=<id>|--id=<id >] [-l]
	     [-N] [-p=<port>|--port=<port>] [-P] [-q=<qdisc>]
             [-R] [-s=<server>|--server=<server] [--stats]
	     [-t=<time>|--time=<time>] [-w] [cubic|dctcp]
  Where:
    out               Egress (default egress)
    -b or --bpf       BPF program filename to load and attach.
                      Default is nrm_out_kern.o for egress,
    -c or -cc         TCP congestion control (cubic or dctcp)
    -d or --delay     Add a delay in ms using netem
    -D                In addition to the goodput in Mbps, it also outputs
                      other detailed information. This information is
                      test dependent (i.e. iperf3 or netperf).
    --debug           Print BPF trace buffer
    -E                Enable ECN (not required for dctcp)
    -f or --flows     Number of concurrent flows (default=1)
    -i or --id        cgroup id (an integer, default is 1)
    -l                Do not limit flows using loopback
    -N                Use netperf instead of iperf3
    -h                Help
    -p or --port      iperf3 port (default is 5201)
    -P                Use an iperf3 instance for each flow
    -q                Use the specified qdisc.
    -r or --rate      Rate in Mbps (default 1s 1Gbps)
    -R                Use TCP_RR for netperf. 1st flow has req
                      size of 10KB, rest of 1MB. Reply in all
                      cases is 1 byte.
                      More detailed output for each flow can be found
                      in the files netperf.<cg>.<flow>, where <cg> is the
                      cgroup id as specified with the -i flag, and <flow>
                      is the flow id starting at 1 and increasing by 1 for
                      flow (as specified by -f).
    -s or --server    hostname of netperf server. Used to create netperf
                      test traffic between to hosts (default is within host)
                      netserver must be running on the host.
    --stats           Get HBM stats (marked, dropped, etc.)
    -t or --time      duration of iperf3 in seconds (default=5)
    -w                Work conserving flag. cgroup can increase its
                      bandwidth beyond the rate limit specified
                      while there is available bandwidth. Current
                      implementation assumes there is only one NIC
                      (eth0), but can be extended to support multiple
                      NICs. This is just a proof of concept.
    cubic or dctcp    specify TCP CC to use

Examples:
 ./do_hbm_test.sh -l -d=1 -D --stats
     Runs a 5 second test, using a single iperf3 flow and with the default
     rate limit of 1Gbps and a delay of 1ms (using netem) using the default
     TCP congestion control on the loopback device (hence we use "-l" to
     enforce bandwidth limit on loopback device). Since no direction is
     specified, it defaults to egress. Since no TCP CC algorithm is
     specified it uses the system default (Cubic for this test).
     With no -D flag, only the value of the AGGREGATE OUTPUT would show.
     id refers to the cgroup id and is useful when running multi cgroup
     tests (supported by a future patch).
     This patchset does not support calling TCP's congesion window
     reduction, even when packets are dropped by the BPF program, resulting
     in a large number of packets dropped. It is recommended that the  current
     HBM implemenation only be used with ECN enabled flows. A future patch
     will add support for reducing TCP's cwnd and will increase the
     performance of non-ECN enabled flows.
   Output:
     Details for HBM in cgroup 1
     id:1
     rate_mbps:493
     duration:4.8 secs
     packets:11355
     bytes_MB:590
     pkts_dropped:4497
     bytes_dropped_MB:292
     pkts_marked_percent: 39.60
     bytes_marked_percent: 49.49
     pkts_dropped_percent: 39.60
     bytes_dropped_percent: 49.49
     PING AVG DELAY:2.075
     AGGREGATE_GOODPUT:505

./do_nrm_test.sh -l -d=1 -D --stats dctcp
     Same as above but using dctcp. Note that fewer bytes are dropped
     (0.01% vs. 49%).
   Output:
     Details for HBM in cgroup 1
     id:1
     rate_mbps:945
     duration:4.9 secs
     packets:16859
     bytes_MB:578
     pkts_dropped:1
     bytes_dropped_MB:0
     pkts_marked_percent: 28.74
     bytes_marked_percent: 45.15
     pkts_dropped_percent:  0.01
     bytes_dropped_percent:  0.01
     PING AVG DELAY:2.083
     AGGREGATE_GOODPUT:965

./do_nrm_test.sh -d=1 -D --stats
     As first example, but without limiting loopback device (i.e. no
     "-l" flag). Since there is no bandwidth limiting, no details for
     HBM are printed out.
   Output:
     Details for HBM in cgroup 1
     PING AVG DELAY:2.019
     AGGREGATE_GOODPUT:42655

./do_hbm.sh -l -d=1 -D --stats -f=2
     Uses iper3 and does 2 flows
./do_hbm.sh -l -d=1 -D --stats -f=4 -P
     Uses iperf3 and does 4 flows, each flow as a separate process.
./do_hbm.sh -l -d=1 -D --stats -f=4 -N
     Uses netperf, 4 flows
./do_hbm.sh -f=1 -r=2000 -t=5 -N -D --stats dctcp -s=<server-name>
     Uses netperf between two hosts. The remote host name is specified
     with -s= and you need to start the program netserver manually on
     the remote host. It will use 1 flow, a rate limit of 2Gbps and dctcp.
./do_hbm.sh -f=1 -r=2000 -t=5 -N -D --stats -w dctcp \
     -s=<server-name>
     As previous, but allows use of extra bandwidth. For this test the
     rate is 8Gbps vs. 1Gbps of the previous test.

Signed-off-by: default avatarLawrence Brakmo <brakmo@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      4ffd44cf
    • brakmo's avatar
      bpf: User program for testing HBM · a1270fe9
      brakmo authored 
      The program nrm creates a cgroup and attaches a BPF program to the
cgroup for testing HBM (Host Bandwidth Manager) for egress traffic.
One still needs to create network traffic. This can be done through
netesto, netperf or iperf3.
A follow-up patch contains a script to create traffic.

USAGE: hbm [-d] [-l] [-n <id>] [-r <rate>] [-s] [-t <secs>]
           [-w] [-h] [prog]
  Where:
   -d        Print BPF trace debug buffer
   -l        Also limit flows doing loopback
   -n <#>    To create cgroup "/hbm#" and attach prog. Default is /nrm1
             This is convenient when testing HBM in more than 1 cgroup
   -r <rate> Rate limit in Mbps
   -s        Get HBM stats (marked, dropped, etc.)
   -t <time> Exit after specified seconds (deault is 0)
   -w        Work conserving flag. cgroup can increase its bandwidth
             beyond the rate limit specified while there is available
             bandwidth. Current implementation assumes there is only
             NIC (eth0), but can be extended to support multiple NICs.
             Currrently only supported for egress. Note, this is just
	     a proof of concept.
   -h        Print this info
   prog      BPF program file name. Name defaults to hbm_out_kern.o

More information about HBM can be found in the paper "BPF Host Resource
Management" presented at the 2018 Linux Plumbers Conference, Networking Track
(http://vger.kernel.org/lpc_net2018_talks/LPC%20BPF%20Network%20Resource%20Paper.pdf

)

Signed-off-by: default avatarLawrence Brakmo <brakmo@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      a1270fe9
    • brakmo's avatar
      bpf: Sample HBM BPF program to limit egress bw · 187d0738
      brakmo authored 
      
A cgroup skb BPF program to limit cgroup output bandwidth.
It uses a modified virtual token bucket queue to limit average
egress bandwidth. The implementation uses credits instead of tokens.
Negative credits imply that queueing would have happened (this is
a virtual queue, so no queueing is done by it. However, queueing may
occur at the actual qdisc (which is not used for rate limiting).

This implementation uses 3 thresholds, one to start marking packets and
the other two to drop packets:
                                 CREDIT
       - <--------------------------|------------------------> +
             |    |          |      0
             |  Large pkt    |
             |  drop thresh  |
  Small pkt drop             Mark threshold
      thresh

The effect of marking depends on the type of packet:
a) If the packet is ECN enabled, then the packet is ECN ce marked.
   The current mark threshold is tuned for DCTCP.
c) Else, it is dropped if it is a large packet.

If the credit is below the drop threshold, the packet is dropped.
Note that dropping a packet through the BPF program does not trigger CWR
(Congestion Window Reduction) in TCP packets. A future patch will add
support for triggering CWR.

This BPF program actually uses 2 drop thresholds, one threshold
for larger packets (>= 120 bytes) and another for smaller packets. This
protects smaller packets such as SYNs, ACKs, etc.

The default bandwidth limit is set at 1Gbps but this can be changed by
a user program through a shared BPF map. In addition, by default this BPF
program does not limit connections using loopback. This behavior can be
overwritten by the user program. There is also an option to calculate
some statistics, such as percent of packets marked or dropped, which
the user program can access.

A latter patch provides such a program (hbm.c)

Signed-off-by: default avatarLawrence Brakmo <brakmo@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      187d0738
    • Yonghong Song's avatar
      samples/bpf: silence compiler warning for xdpsock_user.c · b74e21ab
      Yonghong Song authored 
      
Compiling xdpsock_user.c with 4.8.5, I hit the following
compilation warning:
    HOSTCC  samples/bpf/xdpsock_user.o
  /data/users/yhs/work/net-next/samples/bpf/xdpsock_user.c: In function ‘main’:
  /data/users/yhs/work/net-next/samples/bpf/xdpsock_user.c:449:6: warning: ‘idx_cq’ may be used unini
  tialized in this function [-Wmaybe-uninitialized]
    u32 idx_cq, idx_fq;
        ^
  /data/users/yhs/work/net-next/samples/bpf/xdpsock_user.c:606:7: warning: ‘idx_rx’ may be used unini
  tialized in this function [-Wmaybe-uninitialized]
     u32 idx_rx, idx_tx = 0;
         ^
  /data/users/yhs/work/net-next/samples/bpf/xdpsock_user.c:506:6: warning: ‘idx_rx’ may be used unini
  tialized in this function [-Wmaybe-uninitialized]
    u32 idx_rx, idx_fq = 0;

As an example, the code pattern looks like:
    u32 idx_cq;
    ...
    ret = xsk_ring_prod__reserve(&xsk->umem->fq, rcvd, &idx_fq);
    if (ret) {
      ...
    }
    ... idx_fq ...
The compiler warns since it does not know whether &idx_fq is assigned
or not inside the library function xsk_ring_prod__reserve().

Let us assign an initial value 0 to such auto variables to silence
compiler warning.

Fixes: 248c7f9c ("samples/bpf: convert xdpsock to use libbpf for AF_XDP access")
Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Acked-by: default avatarJonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      b74e21ab
  25. Feb 28, 2019
  27. Feb 27, 2019
  29. Feb 25, 2019
  31. Feb 22, 2019
  33. Feb 12, 2019
  35. Feb 05, 2019
  37. Feb 01, 2019
  39. Jan 30, 2019
  41. Jan 26, 2019
  43. Jan 25, 2019
  45. Jan 15, 2019
    • Yonghong Song's avatar
      samples/bpf: workaround clang asm goto compilation errors · 6bf3bbe1
      Yonghong Song authored 
      
x86 compilation has required asm goto support since 4.17.
Since clang does not support asm goto, at 4.17,
Commit b1ae32db ("x86/cpufeature: Guard asm_volatile_goto usage
for BPF compilation") worked around the issue by permitting an
alternative implementation without asm goto for clang.

At 5.0, more asm goto usages appeared.
  [yhs@148 x86]$ egrep -r asm_volatile_goto
  include/asm/cpufeature.h:     asm_volatile_goto("1: jmp 6f\n"
  include/asm/jump_label.h:     asm_volatile_goto("1:"
  include/asm/jump_label.h:     asm_volatile_goto("1:"
  include/asm/rmwcc.h:  asm_volatile_goto (fullop "; j" #cc " %l[cc_label]"     \
  include/asm/uaccess.h:        asm_volatile_goto("\n"                          \
  include/asm/uaccess.h:        asm_volatile_goto("\n"                          \
  [yhs@148 x86]$

Compiling samples/bpf directories, most bpf programs failed
compilation with error messages like:
  In file included from /home/yhs/work/bpf-next/samples/bpf/xdp_sample_pkts_kern.c:2:
  In file included from /home/yhs/work/bpf-next/include/linux/ptrace.h:6:
  In file included from /home/yhs/work/bpf-next/include/linux/sched.h:15:
  In file included from /home/yhs/work/bpf-next/include/linux/sem.h:5:
  In file included from /home/yhs/work/bpf-next/include/uapi/linux/sem.h:5:
  In file included from /home/yhs/work/bpf-next/include/linux/ipc.h:9:
  In file included from /home/yhs/work/bpf-next/include/linux/refcount.h:72:
  /home/yhs/work/bpf-next/arch/x86/include/asm/refcount.h:70:9: error: 'asm goto' constructs are not supported yet
        return GEN_BINARY_SUFFIXED_RMWcc(LOCK_PREFIX "subl",
               ^
  /home/yhs/work/bpf-next/arch/x86/include/asm/rmwcc.h:67:2: note: expanded from macro 'GEN_BINARY_SUFFIXED_RMWcc'
        __GEN_RMWcc(op " %[val], %[var]\n\t" suffix, var, cc,           \
        ^
  /home/yhs/work/bpf-next/arch/x86/include/asm/rmwcc.h:21:2: note: expanded from macro '__GEN_RMWcc'
        asm_volatile_goto (fullop "; j" #cc " %l[cc_label]"             \
        ^
  /home/yhs/work/bpf-next/include/linux/compiler_types.h:188:37: note: expanded from macro 'asm_volatile_goto'
  #define asm_volatile_goto(x...) asm goto(x)

Most implementation does not even provide an alternative
implementation. And it is also not practical to make changes
for each call site.

This patch workarounded the asm goto issue by redefining the macro like below:
  #define asm_volatile_goto(x...) asm volatile("invalid use of asm_volatile_goto")

If asm_volatile_goto is not used by bpf programs, which is typically the case, nothing bad
will happen. If asm_volatile_goto is used by bpf programs, which is incorrect, the compiler
will issue an error since "invalid use of asm_volatile_goto" is not valid assembly codes.

With this patch, all bpf programs under samples/bpf can pass compilation.

Note that bpf programs under tools/testing/selftests/bpf/ compiled fine as
they do not access kernel internal headers.

Fixes: e769742d ("Revert "x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs"")
Fixes: 18fe5822 ("x86, asm: change the GEN_*_RMWcc() macros to not quote the condition")
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      6bf3bbe1
    • Christian Brauner's avatar
      samples: add binderfs sample program · 9762dc14
      Christian Brauner authored 
      
This adds a simple sample program mounting binderfs and adding, then
removing a binder device.  Hopefully, it will be helpful to users who want
to know how binderfs is supposed to be used.

Signed-off-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
      9762dc14
  47. Jan 11, 2019
    • Petr Mladek's avatar
      livepatch: Simplify API by removing registration step · 958ef1e3
      Petr Mladek authored 
      
The possibility to re-enable a registered patch was useful for immediate
patches where the livepatch module had to stay until the system reboot.
The improved consistency model allows to achieve the same result by
unloading and loading the livepatch module again.

Also we are going to add a feature called atomic replace. It will allow
to create a patch that would replace all already registered patches.
The aim is to handle dependent patches more securely. It will obsolete
the stack of patches that helped to handle the dependencies so far.
Then it might be unclear when a cumulative patch re-enabling is safe.

It would be complicated to support the many modes. Instead we could
actually make the API and code easier to understand.

Therefore, remove the two step public API. All the checks and init calls
are moved from klp_register_patch() to klp_enabled_patch(). Also the patch
is automatically freed, including the sysfs interface when the transition
to the disabled state is completed.

As a result, there is never a disabled patch on the top of the stack.
Therefore we do not need to check the stack in __klp_enable_patch().
And we could simplify the check in __klp_disable_patch().

Also the API and logic is much easier. It is enough to call
klp_enable_patch() in module_init() call. The patch can be disabled
by writing '0' into /sys/kernel/livepatch/<patch>/enabled. Then the module
can be removed once the transition finishes and sysfs interface is freed.

The only problem is how to free the structures and kobjects safely.
The operation is triggered from the sysfs interface. We could not put
the related kobject from there because it would cause lock inversion
between klp_mutex and kernfs locks, see kn->count lockdep map.

Therefore, offload the free task to a workqueue. It is perfectly fine:

  + The patch can no longer be used in the livepatch operations.

  + The module could not be removed until the free operation finishes
    and module_put() is called.

  + The operation is asynchronous already when the first
    klp_try_complete_transition() fails and another call
    is queued with a delay.

Suggested-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
Acked-by: default avatarMiroslav Benes <mbenes@suse.cz>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
      958ef1e3