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  1. Mar 02, 2019
    • 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
  3. Feb 28, 2019
  5. Feb 27, 2019
  7. Feb 25, 2019
  9. Feb 22, 2019
  11. Feb 01, 2019
  13. Jan 30, 2019
  15. Jan 26, 2019
  17. 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
  19. Jan 10, 2019
  21. Jan 08, 2019
  23. Jan 07, 2019
  25. Dec 23, 2018
  27. Dec 18, 2018
  29. Dec 17, 2018
  31. Dec 12, 2018
    • Tycho Andersen's avatar
      samples: add an example of seccomp user trap · fec7b669
      Tycho Andersen authored 
      
The idea here is just to give a demonstration of how one could safely use
the SECCOMP_RET_USER_NOTIF feature to do mount policies. This particular
policy is (as noted in the comment) not very interesting, but it serves to
illustrate how one might apply a policy dodging the various TOCTOU issues.

Signed-off-by: default avatarTycho Andersen <tycho@tycho.ws>
CC: Kees Cook <keescook@chromium.org>
CC: Andy Lutomirski <luto@amacapital.net>
CC: Oleg Nesterov <oleg@redhat.com>
CC: Eric W. Biederman <ebiederm@xmission.com>
CC: "Serge E. Hallyn" <serge@hallyn.com>
CC: Christian Brauner <christian@brauner.io>
CC: Tyler Hicks <tyhicks@canonical.com>
CC: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      fec7b669
  33. Dec 03, 2018
  35. Dec 01, 2018
  37. Nov 23, 2018
    • Daniel T. Lee's avatar
      samples: bpf: fix: error handling regarding kprobe_events · 5a863813
      Daniel T. Lee authored 
      
Currently, kprobe_events failure won't be handled properly.
Due to calling system() indirectly to write to kprobe_events,
it can't be identified whether an error is derived from kprobe or system.

    // buf = "echo '%c:%s %s' >> /s/k/d/t/kprobe_events"
    err = system(buf);
    if (err < 0) {
        printf("failed to create kprobe ..");
        return -1;
    }

For example, running ./tracex7 sample in ext4 partition,
"echo p:open_ctree open_ctree >> /s/k/d/t/kprobe_events"
gets 256 error code system() failure.
=> The error comes from kprobe, but it's not handled correctly.

According to man of system(3), it's return value
just passes the termination status of the child shell
rather than treating the error as -1. (don't care success)

Which means, currently it's not working as desired.
(According to the upper code snippet)

    ex) running ./tracex7 with ext4 env.
    # Current Output
    sh: echo: I/O error
    failed to open event open_ctree

    # Desired Output
    failed to create kprobe 'open_ctree' error 'No such file or directory'

The problem is, error can't be verified whether from child ps
or system. But using write() directly can verify the command
failure, and it will treat all error as -1. So I suggest using
write() directly to 'kprobe_events' rather than calling system().

Signed-off-by: default avatarDaniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      5a863813
  39. Nov 20, 2018
  41. Nov 07, 2018
  43. Oct 11, 2018
  45. Oct 10, 2018
  47. Oct 04, 2018
    • Bo YU's avatar
      bpf, tracex3_user: erase "ARRAY_SIZE" redefined · 20cdeb54
      Bo YU authored 
      
There is a warning when compiling bpf sample programs in sample/bpf:

  make -C /home/foo/bpf/samples/bpf/../../tools/lib/bpf/ RM='rm -rf' LDFLAGS= srctree=/home/foo/bpf/samples/bpf/../../ O=
    HOSTCC  /home/foo/bpf/samples/bpf/tracex3_user.o
  /home/foo/bpf/samples/bpf/tracex3_user.c:20:0: warning: "ARRAY_SIZE" redefined
   #define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))

  In file included from /home/foo/bpf/samples/bpf/tracex3_user.c:18:0:
  ./tools/testing/selftests/bpf/bpf_util.h:48:0: note: this is the location of the previous definition
   # define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))

Signed-off-by: default avatarBo YU <tsu.yubo@gmail.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      20cdeb54
  49. Oct 02, 2018
  51. Oct 01, 2018
    • Roman Gushchin's avatar
      samples/bpf: extend test_cgrp2_attach2 test to use per-cpu cgroup storage · 5fcbd29b
      Roman Gushchin authored 
      
This commit extends the test_cgrp2_attach2 test to cover per-cpu
cgroup storage. Bpf program will use shared and per-cpu cgroup
storages simultaneously, so a better coverage of corresponding
core code will be achieved.

Expected output:
  $ ./test_cgrp2_attach2
  Attached DROP prog. This ping in cgroup /foo should fail...
  ping: sendmsg: Operation not permitted
  Attached DROP prog. This ping in cgroup /foo/bar should fail...
  ping: sendmsg: Operation not permitted
  Attached PASS prog. This ping in cgroup /foo/bar should pass...
  Detached PASS from /foo/bar while DROP is attached to /foo.
  This ping in cgroup /foo/bar should fail...
  ping: sendmsg: Operation not permitted
  Attached PASS from /foo/bar and detached DROP from /foo.
  This ping in cgroup /foo/bar should pass...
  ### override:PASS
  ### multi:PASS

Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      5fcbd29b
  53. Sep 21, 2018
    • Prashant Bhole's avatar
      samples/bpf: fix compilation failure · 32c00979
      Prashant Bhole authored 
      
following commit:
commit d58e468b ("flow_dissector: implements flow dissector BPF hook")
added struct bpf_flow_keys which conflicts with the struct with
same name in sockex2_kern.c and sockex3_kern.c

similar to commit:
commit 534e0e52 ("samples/bpf: fix a compilation failure")
we tried the rename it "flow_keys" but it also conflicted with struct
having same name in include/net/flow_dissector.h. Hence renaming the
struct to "flow_key_record". Also, this commit doesn't fix the
compilation error completely because the similar struct is present in
sockex3_kern.c. Hence renaming it in both files sockex3_user.c and
sockex3_kern.c

Signed-off-by: default avatarPrashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      32c00979
  55. Sep 18, 2018