1. 13 Dec, 2017 1 commit
    • Yonghong Song's avatar
      bpf/tracing: fix kernel/events/core.c compilation error · f4e2298e
      Yonghong Song authored
      Commit f371b304 ("bpf/tracing: allow user space to
      query prog array on the same tp") introduced a perf
      ioctl command to query prog array attached to the
      same perf tracepoint. The commit introduced a
      compilation error under certain config conditions, e.g.,
        (1). CONFIG_BPF_SYSCALL is not defined, or
        (2). CONFIG_TRACING is defined but neither CONFIG_UPROBE_EVENTS
             nor CONFIG_KPROBE_EVENTS is defined.
      
      Error message:
        kernel/events/core.o: In function `perf_ioctl':
        core.c:(.text+0x98c4): undefined reference to `bpf_event_query_prog_array'
      
      This patch fixed this error by guarding the real definition under
      CONFIG_BPF_EVENTS and provided static inline dummy function
      if CONFIG_BPF_EVENTS was not defined.
      It renamed the function from bpf_event_query_prog_array to
      perf_event_query_prog_array and moved the definition from linux/bpf.h
      to linux/trace_events.h so the definition is in proximity to
      other prog_array related functions.
      
      Fixes: f371b304 ("bpf/tracing: allow user space to query prog array on the same tp")
      Reported-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
      Signed-off-by: default avatarYonghong Song <yhs@fb.com>
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      f4e2298e
  2. 12 Dec, 2017 10 commits
    • Alexei Starovoitov's avatar
      Merge branch 'bpf-override-return' · 553a8f2f
      Alexei Starovoitov authored
      Josef Bacik says:
      
      ====================
      This is the same as v8, just rebased onto the bpf tree.
      
      v8->v9:
      - rebased onto the bpf tree.
      
      v7->v8:
      - removed the _ASM_KPROBE_ERROR_INJECT since it was not needed.
      
      v6->v7:
      - moved the opt-in macro to bpf.h out of kprobes.h.
      
      v5->v6:
      - add BPF_ALLOW_ERROR_INJECTION() tagging for functions that will support this
        feature.  This way only functions that opt-in will be allowed to be
        overridden.
      - added a btrfs patch to allow error injection for open_ctree() so that the bpf
        sample actually works.
      
      v4->v5:
      - disallow kprobe_override programs from being put in the prog map array so we
        don't tail call into something we didn't check.  This allows us to make the
        normal path still fast without a bunch of percpu operations.
      
      v3->v4:
      - fix a build error found by kbuild test bot (I didn't wait long enough
        apparently.)
      - Added a warning message as per Daniels suggestion.
      
      v2->v3:
      - added a ->kprobe_override flag to bpf_prog.
      - added some sanity checks to disallow attaching bpf progs that have
        ->kprobe_override set that aren't for ftrace kprobes.
      - added the trace_kprobe_ftrace helper to check if the trace_event_call is a
        ftrace kprobe.
      - renamed bpf_kprobe_state to bpf_kprobe_override, fixed it so we only read this
        value in the kprobe path, and thus only write to it if we're overriding or
        clearing the override.
      
      v1->v2:
      - moved things around to make sure that bpf_override_return could really only be
        used for an ftrace kprobe.
      - killed the special return values from trace_call_bpf.
      - renamed pc_modified to bpf_kprobe_state so bpf_override_return could tell if
        it was being called from an ftrace kprobe context.
      - reworked the logic in kprobe_perf_func to take advantage of bpf_kprobe_state.
      - updated the test as per Alexei's review.
      
      - Original message -
      
      A lot of our error paths are not well tested because we have no good way of
      injecting errors generically.  Some subystems (block, memory) have ways to
      inject errors, but they are random so it's hard to get reproduceable results.
      
      With BPF we can add determinism to our error injection.  We can use kprobes and
      other things to verify we are injecting errors at the exact case we are trying
      to test.  This patch gives us the tool to actual do the error injection part.
      It is very simple, we just set the return value of the pt_regs we're given to
      whatever we provide, and then override the PC with a dummy function that simply
      returns.
      
      Right now this only works on x86, but it would be simple enough to expand to
      other architectures.  Thanks,
      
      Josef
      ====================
      
      In patch "bpf: add a bpf_override_function helper" Alexei moved
      "ifdef CONFIG_BPF_KPROBE_OVERRIDE" few lines to fail program loading
      when kprobe_override is not available instead of failing at run-time.
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      553a8f2f
    • Josef Bacik's avatar
      btrfs: allow us to inject errors at io_ctl_init · 023f46c5
      Josef Bacik authored
      This was instrumental in reproducing a space cache bug.
      Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
      Acked-by: default avatarIngo Molnar <mingo@kernel.org>
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      023f46c5
    • Josef Bacik's avatar
      samples/bpf: add a test for bpf_override_return · 965de87e
      Josef Bacik authored
      This adds a basic test for bpf_override_return to verify it works.  We
      override the main function for mounting a btrfs fs so it'll return
      -ENOMEM and then make sure that trying to mount a btrfs fs will fail.
      Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
      Acked-by: default avatarIngo Molnar <mingo@kernel.org>
      Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      965de87e
    • Josef Bacik's avatar
      bpf: add a bpf_override_function helper · 9802d865
      Josef Bacik authored
      Error injection is sloppy and very ad-hoc.  BPF could fill this niche
      perfectly with it's kprobe functionality.  We could make sure errors are
      only triggered in specific call chains that we care about with very
      specific situations.  Accomplish this with the bpf_override_funciton
      helper.  This will modify the probe'd callers return value to the
      specified value and set the PC to an override function that simply
      returns, bypassing the originally probed function.  This gives us a nice
      clean way to implement systematic error injection for all of our code
      paths.
      Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
      Acked-by: default avatarIngo Molnar <mingo@kernel.org>
      Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      9802d865
    • Josef Bacik's avatar
      btrfs: make open_ctree error injectable · 8556e509
      Josef Bacik authored
      This allows us to do error injection with BPF for open_ctree.
      Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
      Acked-by: default avatarIngo Molnar <mingo@kernel.org>
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      8556e509
    • Josef Bacik's avatar
      add infrastructure for tagging functions as error injectable · 92ace999
      Josef Bacik authored
      Using BPF we can override kprob'ed functions and return arbitrary
      values.  Obviously this can be a bit unsafe, so make this feature opt-in
      for functions.  Simply tag a function with KPROBE_ERROR_INJECT_SYMBOL in
      order to give BPF access to that function for error injection purposes.
      Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
      Acked-by: default avatarIngo Molnar <mingo@kernel.org>
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      92ace999
    • Alexei Starovoitov's avatar
      Merge branch 'bpf-tracing-multiprog-tp-query' · a23967c1
      Alexei Starovoitov authored
      Yonghong Song says:
      
      ====================
      Commit e87c6bc3 ("bpf: permit multiple bpf attachments
      for a single perf event") added support to attach multiple
      bpf programs to a single perf event. Given a perf event
      (kprobe, uprobe, or kernel tracepoint), the perf ioctl interface
      is used to query bpf programs attached to the same trace event.
      
      There already exists a BPF_PROG_QUERY command for introspection
      currently used by cgroup+bpf. We did have an implementation for
      querying tracepoint+bpf through the same interface. However, it
      looks cleaner to use ioctl() style of api here, since attaching
      bpf prog to tracepoint/kuprobe is also done via ioctl.
      
      Patch #1 had the core implementation and patch #2 added
      a test case in tools bpf selftests suite.
      
      Changelogs:
      v3 -> v4:
        - Fix a compilation error with newer gcc like 6.3.1 while
          old gcc 4.8.5 is okay. I was using &uquery->ids to represent
          the address to the ids array to make it explicit that the
          address is passed, and this syntax is rightly rejected
          by gcc 6.3.1.
      v2 -> v3:
        - Change uapi structure perf_event_query_bpf to be more
          clearer based on Peter's suggestion, and adjust
          other codes accordingly.
      v1 -> v2:
        - Rebase on top of net-next.
        - Use existing bpf_prog_array_length function instead of
          implementing the same functionality in function
          bpf_prog_array_copy_info.
      ====================
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      a23967c1
    • Yonghong Song's avatar
      bpf/tracing: add a bpf test for new ioctl query interface · d279f1f8
      Yonghong Song authored
      Added a subtest in test_progs. The tracepoint is
      sched/sched_switch. Multiple bpf programs are attached to
      this tracepoint and the query interface is exercised.
      Signed-off-by: default avatarYonghong Song <yhs@fb.com>
      Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
      Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      d279f1f8
    • Yonghong Song's avatar
      bpf/tracing: allow user space to query prog array on the same tp · f371b304
      Yonghong Song authored
      Commit e87c6bc3 ("bpf: permit multiple bpf attachments
      for a single perf event") added support to attach multiple
      bpf programs to a single perf event.
      Although this provides flexibility, users may want to know
      what other bpf programs attached to the same tp interface.
      Besides getting visibility for the underlying bpf system,
      such information may also help consolidate multiple bpf programs,
      understand potential performance issues due to a large array,
      and debug (e.g., one bpf program which overwrites return code
      may impact subsequent program results).
      
      Commit 2541517c ("tracing, perf: Implement BPF programs
      attached to kprobes") utilized the existing perf ioctl
      interface and added the command PERF_EVENT_IOC_SET_BPF
      to attach a bpf program to a tracepoint. This patch adds a new
      ioctl command, given a perf event fd, to query the bpf program
      array attached to the same perf tracepoint event.
      
      The new uapi ioctl command:
        PERF_EVENT_IOC_QUERY_BPF
      
      The new uapi/linux/perf_event.h structure:
        struct perf_event_query_bpf {
             __u32	ids_len;
             __u32	prog_cnt;
             __u32	ids[0];
        };
      
      User space provides buffer "ids" for kernel to copy to.
      When returning from the kernel, the number of available
      programs in the array is set in "prog_cnt".
      
      The usage:
        struct perf_event_query_bpf *query =
          malloc(sizeof(*query) + sizeof(u32) * ids_len);
        query.ids_len = ids_len;
        err = ioctl(pmu_efd, PERF_EVENT_IOC_QUERY_BPF, query);
        if (err == 0) {
          /* query.prog_cnt is the number of available progs,
           * number of progs in ids: (ids_len == 0) ? 0 : query.prog_cnt
           */
        } else if (errno == ENOSPC) {
          /* query.ids_len number of progs copied,
           * query.prog_cnt is the number of available progs
           */
        } else {
            /* other errors */
        }
      Signed-off-by: default avatarYonghong Song <yhs@fb.com>
      Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
      Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      f371b304
    • Naresh Kamboju's avatar
      selftests: bpf: Adding config fragment CONFIG_CGROUP_BPF=y · 63060c39
      Naresh Kamboju authored
      CONFIG_CGROUP_BPF=y is required for test_dev_cgroup test case.
      Signed-off-by: default avatarNaresh Kamboju <naresh.kamboju@linaro.org>
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      63060c39
  3. 08 Dec, 2017 5 commits
    • Daniel Borkmann's avatar
      Merge branch 'bpf-bpftool-makefile-cleanups' · 97c50589
      Daniel Borkmann authored
      Quentin Monnet says:
      
      ====================
      First patch of this series cleans up the two Makefiles (Makefile and
      Documentation/Makefile) and make their contents more consistent.
      
      The second one add "uninstall" and "doc-uninstall" targets, to remove
      files previously installed on the system with "install" and "doc-install"
      targets.
      ====================
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      97c50589
    • Quentin Monnet's avatar
      tools: bpftool: create "uninstall", "doc-uninstall" make targets · d3244248
      Quentin Monnet authored
      Create two targets to remove executable and documentation that would
      have been previously installed with `make install` and `make
      doc-install`.
      
      Also create a "QUIET_UNINST" helper in tools/scripts/Makefile.include.
      
      Do not attempt to remove directories /usr/local/sbin and
      /usr/share/bash-completions/completions, even if they are empty, as
      those specific directories probably already existed on the system before
      we installed the program, and we do not wish to break other makefiles
      that might assume their existence. Do remvoe /usr/local/share/man/man8
      if empty however, as this directory does not seem to exist by default.
      Signed-off-by: default avatarQuentin Monnet <quentin.monnet@netronome.com>
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      d3244248
    • Quentin Monnet's avatar
      tools: bpftool: harmonise Makefile and Documentation/Makefile · 658e85aa
      Quentin Monnet authored
      Several minor fixes and harmonisation items for Makefiles:
      
      * Use the same mechanism for verbose/non-verbose output in two files
        ("$(Q)"), for all commands.
      * Use calls to "QUIET_INSTALL" and equivalent in Makefile. In
        particular, use "call(descend, ...)" instead of "make -C" to run
        documentation targets.
      * Add a "doc-clean" target, aligned on "doc" and "doc-install".
      * Make "install" target in Makefile depend on "bpftool".
      * Remove condition on DESTDIR to initialise prefix in doc Makefile.
      * Remove modification of VPATH based on OUTPUT, it is unused.
      * Formatting: harmonise spaces around equal signs.
      * Make install path for man pages /usr/local/man instead of
        /usr/local/share/man (respects the Makefile conventions, and the
        latter is usually a symbolic link to the former anyway).
      * Do not erase prefix if set by user in bpftool Makefile.
      * Fix install target for bpftool: append DESTDIR to install path.
      Signed-off-by: default avatarQuentin Monnet <quentin.monnet@netronome.com>
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      658e85aa
    • David S. Miller's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next · 62cd2770
      David S. Miller authored
      Alexei Starovoitov says:
      
      ====================
      pull-request: bpf-next 2017-12-07
      
      The following pull-request contains BPF updates for your net-next tree.
      
      The main changes are:
      
      1) Detailed documentation of BPF development process from Daniel.
      
      2) Addition of is_fullsock, snd_cwnd and srtt_us fields to bpf_sock_ops
         from Lawrence.
      
      3) Minor follow up for bpf_skb_set_tunnel_key() from William.
      ====================
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      62cd2770
    • Jason Wang's avatar
      tuntap: fix possible deadlock when fail to register netdev · 124da8f6
      Jason Wang authored
      Private destructor could be called when register_netdev() fail with
      rtnl lock held. This will lead deadlock in tun_free_netdev() who tries
      to hold rtnl_lock. Fixing this by switching to use spinlock to
      synchronize.
      
      Fixes: 96f84061 ("tun: add eBPF based queue selection method")
      Reported-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
      Cc: Eric Dumazet <eric.dumazet@gmail.com>
      Cc: Willem de Bruijn <willemb@google.com>
      Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
      Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
      Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      124da8f6
  4. 07 Dec, 2017 9 commits
  5. 06 Dec, 2017 15 commits