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  1. 17 Apr, 2019 11 commits
  3. 16 Apr, 2019 16 commits
  5. 13 Apr, 2019 4 commits
  7. 12 Apr, 2019 9 commits
    • Andrey Ignatov's avatar
      bpf: Fix distinct pointer types warning for ARCH=i386 · 51356ac8
      Andrey Ignatov authored 
      Fix a new warning reported by kbuild for make ARCH=i386:

   In file included from kernel/bpf/cgroup.c:11:0:
   kernel/bpf/cgroup.c: In function '__cgroup_bpf_run_filter_sysctl':
   include/linux/kernel.h:827:29: warning: comparison of distinct pointer types lacks a cast
      (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
                                ^
   include/linux/kernel.h:841:4: note: in expansion of macro '__typecheck'
      (__typecheck(x, y) && __no_side_effects(x, y))
       ^~~~~~~~~~~
   include/linux/kernel.h:851:24: note: in expansion of macro '__safe_cmp'
     __builtin_choose_expr(__safe_cmp(x, y), \
                           ^~~~~~~~~~
   include/linux/kernel.h:860:19: note: in expansion of macro '__careful_cmp'
    #define min(x, y) __careful_cmp(x, y, <)
                      ^~~~~~~~~~~~~
>> kernel/bpf/cgroup.c:837:17: note: in expansion of macro 'min'
      ctx.new_len = min(PAGE_SIZE, *pcount);
                    ^~~

Fixes: 4e63acdf ("bpf: Introduce bpf_sysctl_{get,set}_new_value helpers")
Signed-off-by: default avatarAndrey Ignatov <rdna@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      51356ac8
    • Alexei Starovoitov's avatar
      Merge branch 'bpf-sysctl-hook' · a43d0508
      Alexei Starovoitov authored 
      Andrey Ignatov says:

====================
v2->v3:
- simplify C based selftests by relying on variable offset stack access.

v1->v2:
- add fs/proc/proc_sysctl.c mainteners to Cc:.

The patch set introduces new BPF hook for sysctl.

It adds new program type BPF_PROG_TYPE_CGROUP_SYSCTL and attach type
BPF_CGROUP_SYSCTL.

BPF_CGROUP_SYSCTL hook is placed before calling to sysctl's proc_handler so
that accesses (read/write) to sysctl can be controlled for specific cgroup
and either allowed or denied, or traced.

The hook has access to sysctl name, current sysctl value and (on write
only) to new sysctl value via corresponding helpers. New sysctl value can
be overridden by program. Both name and values (current/new) are
represented as strings same way they're visible in /proc/sys/. It is up to
program to parse these strings.

To help with parsing the most common kind of sysctl value, vector of
integers, two new helpers are provided: bpf_strtol and bpf_strtoul with
semantic similar to user space strtol(3) and strtoul(3).

The hook also provides bpf_sysctl context with two fields:
* @write indicates whether sysctl is being read (= 0) or written (= 1);
* @file_pos is sysctl file position to read from or write to, can be
  overridden.

The hook allows to make better isolation for containerized applications
that are run as root so that one container can't change a sysctl and affect
all other containers on a host, make changes to allowed sysctl in a safer
way and simplify sysctl tracing for cgroups.

Patch 1 is preliminary refactoring.
Patch 2 adds new program and attach types.
Patches 3-5 implement helpers to access sysctl name and value.
Patch 6 adds file_pos field to bpf_sysctl context.
Patch 7 updates UAPI in tools.
Patches 8-9 add support for the new hook to libbpf and corresponding test.
Patches 10-14 add selftests for the new hook.
Patch 15 adds support for new arg types to verifier: pointer to integer.
Patch 16 adds bpf_strto{l,ul} helpers to parse integers from sysctl value.
Patch 17 updates UAPI in tools.
Patch 18 updates bpf_helpers.h.
Patch 19 adds selftests for pointer to integer in verifier.
Patches 20-21 add selftests for bpf_strto{l,ul}, including integration
              C based test for sysctl value parsing.
====================
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      a43d0508
    • Andrey Ignatov's avatar
      selftests/bpf: C based test for sysctl and strtoX · 7568f4cb
      Andrey Ignatov authored 
      Add C based test for a few bpf_sysctl_* helpers and bpf_strtoul.

Make sure that sysctl can be identified by name and that multiple
integers can be parsed from sysctl value with bpf_strtoul.

net/ipv4/tcp_mem is chosen as a testing sysctl, it contains 3 unsigned
longs, they all are parsed and compared (val[0] < val[1] < val[2]).

Example of output:
  # ./test_sysctl
  ...
  Test case: C prog: deny all writes .. [PASS]
  Test case: C prog: deny access by name .. [PASS]
  Test case: C prog: read tcp_mem .. [PASS]
  Summary: 39 PASSED, 0 FAILED
Signed-off-by: default avatarAndrey Ignatov <rdna@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      7568f4cb
    • Andrey Ignatov's avatar
      selftests/bpf: Test bpf_strtol and bpf_strtoul helpers · 8549ddc8
      Andrey Ignatov authored 
      Test that bpf_strtol and  bpf_strtoul helpers can be used to convert
provided buffer to long or unsigned long correspondingly and return both
correct result and number of consumed bytes, or proper errno.

Example of output:
  # ./test_sysctl
  ..
  Test case: bpf_strtoul one number string .. [PASS]
  Test case: bpf_strtoul multi number string .. [PASS]
  Test case: bpf_strtoul buf_len = 0, reject .. [PASS]
  Test case: bpf_strtoul supported base, ok .. [PASS]
  Test case: bpf_strtoul unsupported base, EINVAL .. [PASS]
  Test case: bpf_strtoul buf with spaces only, EINVAL .. [PASS]
  Test case: bpf_strtoul negative number, EINVAL .. [PASS]
  Test case: bpf_strtol negative number, ok .. [PASS]
  Test case: bpf_strtol hex number, ok .. [PASS]
  Test case: bpf_strtol max long .. [PASS]
  Test case: bpf_strtol overflow, ERANGE .. [PASS]
  Summary: 36 PASSED, 0 FAILED
Signed-off-by: default avatarAndrey Ignatov <rdna@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      8549ddc8
    • Andrey Ignatov's avatar
      selftests/bpf: Test ARG_PTR_TO_LONG arg type · c2d5f12e
      Andrey Ignatov authored 
      Test that verifier handles new argument types properly, including
uninitialized or partially initialized value, misaligned stack access,
etc.

Example of output:
  #456/p ARG_PTR_TO_LONG uninitialized OK
  #457/p ARG_PTR_TO_LONG half-uninitialized OK
  #458/p ARG_PTR_TO_LONG misaligned OK
  #459/p ARG_PTR_TO_LONG size < sizeof(long) OK
  #460/p ARG_PTR_TO_LONG initialized OK
Signed-off-by: default avatarAndrey Ignatov <rdna@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      c2d5f12e
    • Andrey Ignatov's avatar
      selftests/bpf: Add sysctl and strtoX helpers to bpf_helpers.h · 99f57973
      Andrey Ignatov authored 
      Add bpf_sysctl_* and bpf_strtoX helpers to bpf_helpers.h.
Signed-off-by: default avatarAndrey Ignatov <rdna@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      99f57973
    • Andrey Ignatov's avatar
      bpf: Sync bpf.h to tools/ · b457e553
      Andrey Ignatov authored 
      Sync bpf_strtoX related bpf UAPI changes to tools/.
Signed-off-by: default avatarAndrey Ignatov <rdna@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      b457e553
    • Andrey Ignatov's avatar
      bpf: Introduce bpf_strtol and bpf_strtoul helpers · d7a4cb9b
      Andrey Ignatov authored 
      Add bpf_strtol and bpf_strtoul to convert a string to long and unsigned
long correspondingly. It's similar to user space strtol(3) and
strtoul(3) with a few changes to the API:

* instead of NUL-terminated C string the helpers expect buffer and
  buffer length;

* resulting long or unsigned long is returned in a separate
  result-argument;

* return value is used to indicate success or failure, on success number
  of consumed bytes is returned that can be used to identify position to
  read next if the buffer is expected to contain multiple integers;

* instead of *base* argument, *flags* is used that provides base in 5
  LSB, other bits are reserved for future use;

* number of supported bases is limited.

Documentation for the new helpers is provided in bpf.h UAPI.

The helpers are made available to BPF_PROG_TYPE_CGROUP_SYSCTL programs to
be able to convert string input to e.g. "ulongvec" output.

E.g. "net/ipv4/tcp_mem" consists of three ulong integers. They can be
parsed by calling to bpf_strtoul three times.

Implementation notes:

Implementation includes "../../lib/kstrtox.h" to reuse integer parsing
functions. It's done exactly same way as fs/proc/base.c already does.

Unfortunately existing kstrtoX function can't be used directly since
they fail if any invalid character is present right after integer in the
string. Existing simple_strtoX functions can't be used either since
they're obsolete and don't handle overflow properly.
Signed-off-by: default avatarAndrey Ignatov <rdna@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      d7a4cb9b
    • Andrey Ignatov's avatar
      bpf: Introduce ARG_PTR_TO_{INT,LONG} arg types · 57c3bb72
      Andrey Ignatov authored 
      Currently the way to pass result from BPF helper to BPF program is to
provide memory area defined by pointer and size: func(void *, size_t).

It works great for generic use-case, but for simple types, such as int,
it's overkill and consumes two arguments when it could use just one.

Introduce new argument types ARG_PTR_TO_INT and ARG_PTR_TO_LONG to be
able to pass result from helper to program via pointer to int and long
correspondingly: func(int *) or func(long *).

New argument types are similar to ARG_PTR_TO_MEM with the following
differences:
* they don't require corresponding ARG_CONST_SIZE argument, predefined
  access sizes are used instead (32bit for int, 64bit for long);
* it's possible to use more than one such an argument in a helper;
* provided pointers have to be aligned.

It's easy to introduce similar ARG_PTR_TO_CHAR and ARG_PTR_TO_SHORT
argument types. It's not done due to lack of use-case though.
Signed-off-by: default avatarAndrey Ignatov <rdna@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      57c3bb72
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