Add documentation for BPF_PROG_TYPE_CGROUP_SYSCTL, including general
info, attach type, context, return code, helpers, example and usage
considerations.
A separate file prog_cgroup_sysctl.rst is added to Documentation/bpf/.
In the future more program types can be documented in their own
prog_<name>.rst files.
Another way to place program type specific documentation would be to
group program types somehow (e.g. cgroup.rst for all cgroup-bpf
programs), but it may not scale well since some program types may belong
to different groups, e.g. BPF_PROG_TYPE_CGROUP_SKB can be documented
together with either cgroup-bpf programs or programs that access skb.
The new file is added to the index and verified by `make htmldocs` /
sanity-check by lynx.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add support for recently added BPF_PROG_TYPE_CGROUP_SYSCTL program type
and BPF_CGROUP_SYSCTL attach type.
Example of bpftool output with sysctl program from selftests:
# bpftool p load ./test_sysctl_prog.o /mnt/bpf/sysctl_prog type cgroup/sysctl
# bpftool p l
9: cgroup_sysctl name sysctl_tcp_mem tag 0dd05f81a8d0d52e gpl
loaded_at 2019-04-16T12:57:27-0700 uid 0
xlated 1008B jited 623B memlock 4096B
# bpftool c a /mnt/cgroup2/bla sysctl id 9
# bpftool c t
CgroupPath
ID AttachType AttachFlags Name
/mnt/cgroup2/bla
9 sysctl sysctl_tcp_mem
# bpftool c d /mnt/cgroup2/bla sysctl id 9
# bpftool c t
CgroupPath
ID AttachType AttachFlags Name
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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: 4e63acdff8 ("bpf: Introduce bpf_sysctl_{get,set}_new_value helpers")
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Test access to file_pos field of bpf_sysctl context, both read (incl.
narrow read) and write.
# ./test_sysctl
...
Test case: ctx:file_pos sysctl:read read ok .. [PASS]
Test case: ctx:file_pos sysctl:read read ok narrow .. [PASS]
Test case: ctx:file_pos sysctl:read write ok .. [PASS]
...
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Test that new value provided by user space on sysctl write can be read
by bpf_sysctl_get_new_value and overridden by bpf_sysctl_set_new_value.
# ./test_sysctl
...
Test case: sysctl_get_new_value sysctl:read EINVAL .. [PASS]
Test case: sysctl_get_new_value sysctl:write ok .. [PASS]
Test case: sysctl_get_new_value sysctl:write ok long .. [PASS]
Test case: sysctl_get_new_value sysctl:write E2BIG .. [PASS]
Test case: sysctl_set_new_value sysctl:read EINVAL .. [PASS]
Test case: sysctl_set_new_value sysctl:write ok .. [PASS]
Summary: 22 PASSED, 0 FAILED
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Test sysctl_get_current_value on sysctl read and write, buffers with
enough space and too small buffers to get E2BIG and truncated result,
etc.
# ./test_sysctl
...
Test case: sysctl_get_current_value sysctl:read ok, gt .. [PASS]
Test case: sysctl_get_current_value sysctl:read ok, eq .. [PASS]
Test case: sysctl_get_current_value sysctl:read E2BIG truncated .. [PASS]
Test case: sysctl_get_current_value sysctl:read EINVAL .. [PASS]
Test case: sysctl_get_current_value sysctl:write ok .. [PASS]
Summary: 16 PASSED, 0 FAILED
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Test w/ and w/o BPF_F_SYSCTL_BASE_NAME, buffers with enough space and
too small buffers to get E2BIG and truncated result, etc.
# ./test_sysctl
...
Test case: sysctl_get_name sysctl_value:base ok .. [PASS]
Test case: sysctl_get_name sysctl_value:base E2BIG truncated .. [PASS]
Test case: sysctl_get_name sysctl:full ok .. [PASS]
Test case: sysctl_get_name sysctl:full E2BIG truncated .. [PASS]
Test case: sysctl_get_name sysctl:full E2BIG truncated small .. [PASS]
Summary: 11 PASSED, 0 FAILED
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add unit test for BPF_PROG_TYPE_CGROUP_SYSCTL program type.
Test that program can allow/deny access.
Test both valid and invalid accesses to ctx->write.
Example of output:
# ./test_sysctl
Test case: sysctl wrong attach_type .. [PASS]
Test case: sysctl:read allow all .. [PASS]
Test case: sysctl:read deny all .. [PASS]
Test case: ctx:write sysctl:read read ok .. [PASS]
Test case: ctx:write sysctl:write read ok .. [PASS]
Test case: ctx:write sysctl:read write reject .. [PASS]
Summary: 6 PASSED, 0 FAILED
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add unit test to verify that program and attach types are properly
identified for "cgroup/sysctl" section name.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Support BPF_PROG_TYPE_CGROUP_SYSCTL program in libbpf: identifying
program and attach types by section name, probe.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add file_pos field to bpf_sysctl context to read and write sysctl file
position at which sysctl is being accessed (read or written).
The field can be used to e.g. override whole sysctl value on write to
sysctl even when sys_write is called by user space with file_pos > 0. Or
BPF program may reject such accesses.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add helpers to work with new value being written to sysctl by user
space.
bpf_sysctl_get_new_value() copies value being written to sysctl into
provided buffer.
bpf_sysctl_set_new_value() overrides new value being written by user
space with a one from provided buffer. Buffer should contain string
representation of the value, similar to what can be seen in /proc/sys/.
Both helpers can be used only on sysctl write.
File position matters and can be managed by an interface that will be
introduced separately. E.g. if user space calls sys_write to a file in
/proc/sys/ at file position = X, where X > 0, then the value set by
bpf_sysctl_set_new_value() will be written starting from X. If program
wants to override whole value with specified buffer, file position has
to be set to zero.
Documentation for the new helpers is provided in bpf.h UAPI.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add bpf_sysctl_get_current_value() helper to copy current sysctl value
into provided by BPF_PROG_TYPE_CGROUP_SYSCTL program buffer.
It provides same string as user space can see by reading corresponding
file in /proc/sys/, including new line, etc.
Documentation for the new helper is provided in bpf.h UAPI.
Since current value is kept in ctl_table->data in a parsed form,
ctl_table->proc_handler() with write=0 is called to read that data and
convert it to a string. Such a string can later be parsed by a program
using helpers that will be introduced separately.
Unfortunately it's not trivial to provide API to access parsed data due to
variety of data representations (string, intvec, uintvec, ulongvec,
custom structures, even NULL, etc). Instead it's assumed that user know
how to handle specific sysctl they're interested in and appropriate
helpers can be used.
Since ctl_table->proc_handler() expects __user buffer, conversion to
__user happens for kernel allocated one where the value is stored.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add bpf_sysctl_get_name() helper to copy sysctl name (/proc/sys/ entry)
into provided by BPF_PROG_TYPE_CGROUP_SYSCTL program buffer.
By default full name (w/o /proc/sys/) is copied, e.g. "net/ipv4/tcp_mem".
If BPF_F_SYSCTL_BASE_NAME flag is set, only base name will be copied,
e.g. "tcp_mem".
Documentation for the new helper is provided in bpf.h UAPI.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Containerized applications may run as root and it may create problems
for whole host. Specifically such applications may change a sysctl and
affect applications in other containers.
Furthermore in existing infrastructure it may not be possible to just
completely disable writing to sysctl, instead such a process should be
gradual with ability to log what sysctl are being changed by a
container, investigate, limit the set of writable sysctl to currently
used ones (so that new ones can not be changed) and eventually reduce
this set to zero.
The patch introduces new program type BPF_PROG_TYPE_CGROUP_SYSCTL and
attach type BPF_CGROUP_SYSCTL to solve these problems on cgroup basis.
New program type has access to following minimal context:
struct bpf_sysctl {
__u32 write;
};
Where @write indicates whether sysctl is being read (= 0) or written (=
1).
Helpers to access sysctl name and value will be introduced separately.
BPF_CGROUP_SYSCTL attach point is added to sysctl code right before
passing control to ctl_table->proc_handler so that BPF program can
either allow or deny access to sysctl.
Suggested-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently kernel/bpf/cgroup.c contains only one program type and one
proto function cgroup_dev_func_proto(). It'd be useful to have base
proto function that can be reused for new cgroup-bpf program types
coming soon.
Introduce cgroup_base_func_proto().
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reported in [1].
With gcc 8.3.0 the following error is issued:
cc -Ibpf@sta -I. -I.. -I.././include -I.././include/uapi
-fdiagnostics-color=always -fsanitize=address,undefined -fno-omit-frame-pointer
-pipe -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -Werror -g -fPIC -g -O2
-Werror -Wall -Wno-pointer-arith -Wno-sign-compare -MD -MQ
'bpf@sta/src_libbpf.c.o' -MF 'bpf@sta/src_libbpf.c.o.d' -o
'bpf@sta/src_libbpf.c.o' -c ../src/libbpf.c
../src/libbpf.c: In function 'bpf_object__elf_collect':
../src/libbpf.c:947:18: error: 'map_def_sz' may be used uninitialized in this
function [-Werror=maybe-uninitialized]
if (map_def_sz <= sizeof(struct bpf_map_def)) {
~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../src/libbpf.c:827:18: note: 'map_def_sz' was declared here
int i, map_idx, map_def_sz, nr_syms, nr_maps = 0, nr_maps_glob = 0;
^~~~~~~~~~
According to [2] -Wmaybe-uninitialized is enabled by -Wall.
Same error is generated by clang's -Wconditional-uninitialized.
[1] https://github.com/libbpf/libbpf/pull/29#issuecomment-481902601
[2] https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
Fixes: d859900c4c ("bpf, libbpf: support global data/bss/rodata sections")
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
vsprintf() in __base_pr() uses nonliteral format string and it breaks
compilation for those who provide corresponding extra CFLAGS, e.g.:
https://github.com/libbpf/libbpf/issues/27
If libbpf is built with the flags from PR:
libbpf.c:68:26: error: format string is not a string literal
[-Werror,-Wformat-nonliteral]
return vfprintf(stderr, format, args);
^~~~~~
1 error generated.
Ignore this warning since the use case in libbpf.c is legit.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
check_stack_access() that prints verbose log is used in
adjust_ptr_min_max_vals() that prints its own verbose log and now they
stick together, e.g.:
variable stack access var_off=(0xfffffffffffffff0; 0x4) off=-16
size=1R2 stack pointer arithmetic goes out of range, prohibited for
!root
Add missing newline so that log is more readable:
variable stack access var_off=(0xfffffffffffffff0; 0x4) off=-16 size=1
R2 stack pointer arithmetic goes out of range, prohibited for !root
Fixes: f1174f77b5 ("bpf/verifier: rework value tracking")
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Test the case when reg->smax_value is too small/big and can overflow,
and separately min and max values outside of stack bounds.
Example of output:
# ./test_verifier
#856/p indirect variable-offset stack access, unbounded OK
#857/p indirect variable-offset stack access, max out of bound OK
#858/p indirect variable-offset stack access, min out of bound OK
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
As discussed in [1] max value of variable offset has to be checked for
overflow on stack access otherwise verifier would accept code like this:
0: (b7) r2 = 6
1: (b7) r3 = 28
2: (7a) *(u64 *)(r10 -16) = 0
3: (7a) *(u64 *)(r10 -8) = 0
4: (79) r4 = *(u64 *)(r1 +168)
5: (c5) if r4 s< 0x0 goto pc+4
R1=ctx(id=0,off=0,imm=0) R2=inv6 R3=inv28
R4=inv(id=0,umax_value=9223372036854775807,var_off=(0x0;
0x7fffffffffffffff)) R10=fp0,call_-1 fp-8=mmmmmmmm fp-16=mmmmmmmm
6: (17) r4 -= 16
7: (0f) r4 += r10
8: (b7) r5 = 8
9: (85) call bpf_getsockopt#57
10: (b7) r0 = 0
11: (95) exit
, where R4 obviosly has unbounded max value.
Fix it by checking that reg->smax_value is inside (-BPF_MAX_VAR_OFF;
BPF_MAX_VAR_OFF) range.
reg->smax_value is used instead of reg->umax_value because stack
pointers are calculated using negative offset from fp. This is opposite
to e.g. map access where offset must be non-negative and where
umax_value is used.
Also dedicated verbose logs are added for both min and max bound check
failures to have diagnostics consistent with variable offset handling in
check_map_access().
[1] https://marc.info/?l=linux-netdev&m=155433357510597&w=2
Fixes: 2011fccfb6 ("bpf: Support variable offset stack access from helpers")
Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Test that verifier rejects indirect stack access with variable offset in
unprivileged mode and accepts same code in privileged mode.
Since pointer arithmetics is prohibited in unprivileged mode verifier
should reject the program even before it gets to helper call that uses
variable offset, at the time when that variable offset is trying to be
constructed.
Example of output:
# ./test_verifier
...
#859/u indirect variable-offset stack access, priv vs unpriv OK
#859/p indirect variable-offset stack access, priv vs unpriv OK
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Proper support of indirect stack access with variable offset in
unprivileged mode (!root) requires corresponding support in Spectre
masking for stack ALU in retrieve_ptr_limit().
There are no use-case for variable offset in unprivileged mode though so
make verifier reject such accesses for simplicity.
Pointer arithmetics is one (and only?) way to cause variable offset and
it's already rejected in unpriv mode so that verifier won't even get to
helper function whose argument contains variable offset, e.g.:
0: (7a) *(u64 *)(r10 -16) = 0
1: (7a) *(u64 *)(r10 -8) = 0
2: (61) r2 = *(u32 *)(r1 +0)
3: (57) r2 &= 4
4: (17) r2 -= 16
5: (0f) r2 += r10
variable stack access var_off=(0xfffffffffffffff0; 0x4) off=-16 size=1R2
stack pointer arithmetic goes out of range, prohibited for !root
Still it looks like a good idea to reject variable offset indirect stack
access for unprivileged mode in check_stack_boundary() explicitly.
Fixes: 2011fccfb6 ("bpf: Support variable offset stack access from helpers")
Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Test that verifier rejects indirect access to uninitialized stack with
variable offset.
Example of output:
# ./test_verifier
...
#859/p indirect variable-offset stack access, uninitialized OK
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
It's hard to guarantee that whole memory is marked as initialized on
helper return if uninitialized stack is accessed with variable offset
since specific bounds are unknown to verifier. This may cause
uninitialized stack leaking.
Reject such an access in check_stack_boundary to prevent possible
leaking.
There are no known use-cases for indirect uninitialized stack access
with variable offset so it shouldn't break anything.
Fixes: 2011fccfb6 ("bpf: Support variable offset stack access from helpers")
Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Test different scenarios of indirect variable-offset stack access: out of
bound access (>0), min_off below initialized part of the stack,
max_off+size above initialized part of the stack, initialized stack.
Example of output:
...
#856/p indirect variable-offset stack access, out of bound OK
#857/p indirect variable-offset stack access, max_off+size > max_initialized OK
#858/p indirect variable-offset stack access, min_off < min_initialized OK
#859/p indirect variable-offset stack access, ok OK
...
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently there is a difference in how verifier checks memory access for
helper arguments for PTR_TO_MAP_VALUE and PTR_TO_STACK with regard to
variable part of offset.
check_map_access, that is used for PTR_TO_MAP_VALUE, can handle variable
offsets just fine, so that BPF program can call a helper like this:
some_helper(map_value_ptr + off, size);
, where offset is unknown at load time, but is checked by program to be
in a safe rage (off >= 0 && off + size < map_value_size).
But it's not the case for check_stack_boundary, that is used for
PTR_TO_STACK, and same code with pointer to stack is rejected by
verifier:
some_helper(stack_value_ptr + off, size);
For example:
0: (7a) *(u64 *)(r10 -16) = 0
1: (7a) *(u64 *)(r10 -8) = 0
2: (61) r2 = *(u32 *)(r1 +0)
3: (57) r2 &= 4
4: (17) r2 -= 16
5: (0f) r2 += r10
6: (18) r1 = 0xffff888111343a80
8: (85) call bpf_map_lookup_elem#1
invalid variable stack read R2 var_off=(0xfffffffffffffff0; 0x4)
Add support for variable offset access to check_stack_boundary so that
if offset is checked by program to be in a safe range it's accepted by
verifier.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add new accessor for bpf_object to get opaque struct btf * from it.
struct btf * is needed for all operations with BTF and it's present in
bpf_object. The only thing missing is a way to get it.
Example use-case is to get BTF key_type_id and value_type_id for a map in
bpf_object. It can be done with btf__get_map_kv_tids() but that function
requires struct btf *.
Similar API can be added for struct btf_ext but no use-case for it yet.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add bpf_map__resize() to change max_entries for a map.
Quite often necessary map size is unknown at compile time and can be
calculated only at run time.
Currently the following approach is used to do so:
* bpf_object__open_buffer() to open Elf file from a buffer;
* bpf_object__find_map_by_name() to find relevant map;
* bpf_map__def() to get map attributes and create struct
bpf_create_map_attr from them;
* update max_entries in bpf_create_map_attr;
* bpf_create_map_xattr() to create new map with updated max_entries;
* bpf_map__reuse_fd() to replace the map in bpf_object with newly
created one.
And after all this bpf_object can finally be loaded. The map will have
new size.
It 1) is quite a lot of steps; 2) doesn't take BTF into account.
For "2)" even more steps should be made and some of them require changes
to libbpf (e.g. to get struct btf * from bpf_object).
Instead the whole problem can be solved by introducing simple
bpf_map__resize() API that checks the map and sets new max_entries if
the map is not loaded yet.
So the new steps are:
* bpf_object__open_buffer() to open Elf file from a buffer;
* bpf_object__find_map_by_name() to find relevant map;
* bpf_map__resize() to update max_entries.
That's much simpler and works with BTF.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Test that sys_sendmsg BPF hook doesn't break sys_sendmsg behaviour to
rewrite destination IPv6 = [::] with [::1] (BSD'ism).
Two test cases are added:
1) User passes dst IPv6 = [::] and BPF_CGROUP_UDP6_SENDMSG program
doesn't touch it.
2) User passes dst IPv6 != [::], but BPF_CGROUP_UDP6_SENDMSG program
rewrites it with [::].
In both cases [::1] is used by sys_sendmsg code eventually and datagram
is sent successfully for unconnected UDP socket.
Example of relevant output:
Test case: sendmsg6: set dst IP = [::] (BSD'ism) .. [PASS]
Test case: sendmsg6: preserve dst IP = [::] (BSD'ism) .. [PASS]
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
sys_sendmsg has supported unspecified destination IPv6 (wildcard) for
unconnected UDP sockets since 876c7f41. When [::] is passed by user as
destination, sys_sendmsg rewrites it with [::1] to be consistent with
BSD (see "BSD'ism" comment in the code).
This didn't work when cgroup-bpf was enabled though since the rewrite
[::] -> [::1] happened before passing control to cgroup-bpf block where
fl6.daddr was updated with passed by user sockaddr_in6.sin6_addr (that
might or might not be changed by BPF program). That way if user passed
[::] as dst IPv6 it was first rewritten with [::1] by original code from
876c7f41, but then rewritten back with [::] by cgroup-bpf block.
It happened even when BPF_CGROUP_UDP6_SENDMSG program was not present
(CONFIG_CGROUP_BPF=y was enough).
The fix is to apply BSD'ism after cgroup-bpf block so that [::] is
replaced with [::1] no matter where it came from: passed by user to
sys_sendmsg or set by BPF_CGROUP_UDP6_SENDMSG program.
Fixes: 1cedee13d2 ("bpf: Hooks for sys_sendmsg")
Reported-by: Nitin Rawat <nitin.rawat@intel.com>
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Semantic of netns_id argument of bpf_sk_lookup_tcp and bpf_sk_lookup_udp
was changed (fixed) in f71c6143c2. Corresponding changes have to be
applied to all call sites in selftests. The patch fixes corresponding
call sites in test_sock_addr test: pass BPF_F_CURRENT_NETNS instead of 0
in netns_id argument.
Fixes: f71c6143c2 ("bpf: Support sk lookup in netns with id 0")
Reported-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Joe Stringer <joe@wand.net.nz>
Tested-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
The whole libbpf is licensed as (LGPL-2.1 OR BSD-2-Clause). I missed it
while adding README.rst. Fix it and use same license as all other files
in libbpf do. Since I'm the only author of README.rst so far, no others'
permissions should be needed.
Fixes: 76d1b894c5 ("libbpf: Document API and ABI conventions")
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Document API and ABI for libbpf: naming convention, symbol visibility,
ABI versioning.
This is just a starting point. Documentation can be significantly
extended in the future to cover more topics.
ABI versioning section touches only a few basic points with a link to
more comprehensive documentation from Ulrich Drepper. This section can
be extended in the future when there is better understanding what works
well and what not so well in libbpf development process and production
usage.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Since ABI versioning info is kept separately from the code it's easy to
forget to update it while adding a new API.
Add simple verification that all global symbols exported with LIBBPF_API
are versioned in libbpf.map version script.
The idea is to check that number of global symbols in libbpf-in.o, that
is the input to the linker, matches with number of unique versioned
symbols in libbpf.so, that is the output of the linker. If these numbers
don't match, it may mean some symbol was not versioned and make will
fail.
"Unique" means that if a symbol is present in more than one version of
ABI due to ABI changes, it'll be counted once.
Another option to calculate number of global symbols in the "input"
could be to count number of LIBBPF_ABI entries in C headers but it seems
to be fragile.
Example of output when a symbol is missing in version script:
...
LD libbpf-in.o
LINK libbpf.a
LINK libbpf.so
Warning: Num of global symbols in libbpf-in.o (115) does NOT match
with num of versioned symbols in libbpf.so (114). Please make sure all
LIBBPF_API symbols are versioned in libbpf.map.
make: *** [check_abi] Error 1
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
More and more projects use libbpf and one day it'll likely be packaged
and distributed as DSO and that requires ABI versioning so that both
compatible and incompatible changes to ABI can be introduced in a safe
way in the future without breaking executables dynamically linked with a
previous version of the library.
Usual way to do ABI versioning is version script for the linker. Add
such a script for libbpf. All global symbols currently exported via
LIBBPF_API macro are added to the version script libbpf.map.
The version name LIBBPF_0.0.1 is constructed from the name of the
library + version specified by $(LIBBPF_VERSION) in Makefile.
Version script does not duplicate the work done by LIBBPF_API macro, it
rather complements it. The macro is used at compile time and can be used
by compiler to do optimization that can't be done at link time, it is
purely about global symbol visibility. The version script, in turn, is
used at link time and takes care of ABI versioning. Both techniques are
described in details in [1].
Whenever ABI is changed in the future, version script should be changed
appropriately.
[1] https://www.akkadia.org/drepper/dsohowto.pdf
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Use bpf_sk_lookup_tcp, bpf_sk_lookup_udp and bpf_sk_release helpers from
test_sock_addr programs to make sure they're available and can lookup
and release socket properly for IPv4/IPv4, TCP/UDP.
Reading from a few fields of returned struct bpf_sock is also tested.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Make bpf_sk_lookup_tcp, bpf_sk_lookup_udp and bpf_sk_release helpers
available in programs of type BPF_PROG_TYPE_CGROUP_SOCK_ADDR.
Such programs operate on sockets and have access to socket and struct
sockaddr passed by user to system calls such as sys_bind, sys_connect,
sys_sendmsg.
It's useful to be able to lookup other sockets from these programs.
E.g. sys_connect may lookup IP:port endpoint and if there is a server
socket bound to that endpoint ("server" can be defined by saddr & sport
being zero), redirect client connection to it by rewriting IP:port in
sockaddr passed to sys_connect.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Lookup functions in sk_lookup have different expectations about byte
order of provided arguments.
Specifically __inet_lookup, __udp4_lib_lookup and __udp6_lib_lookup
expect dport to be in network byte order and do ntohs(dport) internally.
At the same time __inet6_lookup expects dport to be in host byte order
and correspondingly name the argument hnum.
sk_lookup works correctly with __inet_lookup, __udp4_lib_lookup and
__inet6_lookup with regard to dport. But in __udp6_lib_lookup case it
uses host instead of expected network byte order. It makes result
returned by bpf_sk_lookup_udp for IPv6 incorrect.
The patch fixes byte order of dport passed to __udp6_lib_lookup.
Originally sk_lookup properly handled UDPv6, but not TCPv6. 5ef0ae84f0
fixes TCPv6 but breaks UDPv6.
Fixes: 5ef0ae84f0 ("bpf: Fix IPv6 dport byte-order in bpf_sk_lookup")
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Joe Stringer <joe@wand.net.nz>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add more test cases for context bpf_sock_addr to test narrow loads with
offset > 0 for ctx->user_ip4 field (__u32):
* off=1, size=1;
* off=2, size=1;
* off=3, size=1;
* off=2, size=2.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently BPF verifier allows narrow loads for a context field only with
offset zero. E.g. if there is a __u32 field then only the following
loads are permitted:
* off=0, size=1 (narrow);
* off=0, size=2 (narrow);
* off=0, size=4 (full).
On the other hand LLVM can generate a load with offset different than
zero that make sense from program logic point of view, but verifier
doesn't accept it.
E.g. tools/testing/selftests/bpf/sendmsg4_prog.c has code:
#define DST_IP4 0xC0A801FEU /* 192.168.1.254 */
...
if ((ctx->user_ip4 >> 24) == (bpf_htonl(DST_IP4) >> 24) &&
where ctx is struct bpf_sock_addr.
Some versions of LLVM can produce the following byte code for it:
8: 71 12 07 00 00 00 00 00 r2 = *(u8 *)(r1 + 7)
9: 67 02 00 00 18 00 00 00 r2 <<= 24
10: 18 03 00 00 00 00 00 fe 00 00 00 00 00 00 00 00 r3 = 4261412864 ll
12: 5d 32 07 00 00 00 00 00 if r2 != r3 goto +7 <LBB0_6>
where `*(u8 *)(r1 + 7)` means narrow load for ctx->user_ip4 with size=1
and offset=3 (7 - sizeof(ctx->user_family) = 3). This load is currently
rejected by verifier.
Verifier code that rejects such loads is in bpf_ctx_narrow_access_ok()
what means any is_valid_access implementation, that uses the function,
works this way, e.g. bpf_skb_is_valid_access() for __sk_buff or
sock_addr_is_valid_access() for bpf_sock_addr.
The patch makes such loads supported. Offset can be in [0; size_default)
but has to be multiple of load size. E.g. for __u32 field the following
loads are supported now:
* off=0, size=1 (narrow);
* off=1, size=1 (narrow);
* off=2, size=1 (narrow);
* off=3, size=1 (narrow);
* off=0, size=2 (narrow);
* off=2, size=2 (narrow);
* off=0, size=4 (full).
Reported-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Lookup functions in sk_lookup have different expectations about byte
order of provided arguments.
Specifically __inet_lookup, __udp4_lib_lookup and __udp6_lib_lookup
expect dport to be in network byte order and do ntohs(dport) internally.
At the same time __inet6_lookup expects dport to be in host byte order
and correspondingly name the argument hnum.
sk_lookup works correctly with __inet_lookup, __udp4_lib_lookup and
__inet6_lookup with regard to dport. But in __udp6_lib_lookup case it
uses host instead of expected network byte order. It makes result
returned by bpf_sk_lookup_udp for IPv6 incorrect.
The patch fixes byte order of dport passed to __udp6_lib_lookup.
Originally sk_lookup properly handled UDPv6, but not TCPv6. 5ef0ae84f0
fixes TCPv6 but breaks UDPv6.
Fixes: 5ef0ae84f0 ("bpf: Fix IPv6 dport byte-order in bpf_sk_lookup")
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Joe Stringer <joe@wand.net.nz>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Arnaldo Carvalho de Melo reported build error in libbpf when clang
version 3.8.1-24 (tags/RELEASE_381/final) is used:
libbpf.c:2201:36: error: comparison of constant -22 with expression of
type 'const enum bpf_attach_type' is always false
[-Werror,-Wtautological-constant-out-of-range-compare]
if (section_names[i].attach_type == -EINVAL)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~
1 error generated.
Fix the error by keeping "is_attachable" property of a program in a
separate struct field instead of trying to use attach_type itself.
Fixes: 956b620fcf ("libbpf: Introduce libbpf_attach_type_by_name")
Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Make global symbols in libbpf DSO hidden by default with
-fvisibility=hidden and export symbols that are part of ABI explicitly
with __attribute__((visibility("default"))).
This is common practice that should prevent from accidentally exporting
a symbol, that is not supposed to be a part of ABI what, in turn,
improves both libbpf developer- and user-experiences. See [1] for more
details.
Export control becomes more important since more and more projects use
libbpf.
The patch doesn't export a bunch of netlink related functions since as
agreed in [2] they'll be reworked. That doesn't break bpftool since
bpftool links libbpf statically.
[1] https://www.akkadia.org/drepper/dsohowto.pdf (2.2 Export Control)
[2] https://www.mail-archive.com/netdev@vger.kernel.org/msg251434.html
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Make bpf_program__load consistent with other interfaces: use __u32
instead of u32. That in turn fixes build of samples:
In file included from ./samples/bpf/trace_output_user.c:21:0:
./tools/lib/bpf/libbpf.h:132:9: error: unknown type name ‘u32’
u32 kern_version);
^
Fixes: commit 29cd77f416 ("libbpf: Support loading individual progs")
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Rename include guards to have consistent names "__LIBBPF_<header_name>".
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
libbpf is used more and more outside kernel tree. That means the library
should follow good practices in library design and implementation to
play well with third party code that uses it.
One of such practices is to have a common prefix (or a few) for every
interface, function or data structure, library provides. I helps to
avoid name conflicts with other libraries and keeps API consistent.
Inconsistent names in libbpf already cause problems in real life. E.g.
an application can't use both libbpf and libnl due to conflicting
symbols.
Having common prefix will help to fix current and avoid future problems.
libbpf already uses the following prefixes for its interfaces:
* bpf_ for bpf system call wrappers, program/map/elf-object
abstractions and a few other things;
* btf_ for BTF related API;
* libbpf_ for everything else.
The patch renames function in str_error.h to have libbpf_ prefix since it
misses one and doesn't fit well into the first two categories.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
libbpf is used more and more outside kernel tree. That means the library
should follow good practices in library design and implementation to
play well with third party code that uses it.
One of such practices is to have a common prefix (or a few) for every
interface, function or data structure, library provides. I helps to
avoid name conflicts with other libraries and keeps API consistent.
Inconsistent names in libbpf already cause problems in real life. E.g.
an application can't use both libbpf and libnl due to conflicting
symbols.
Having common prefix will help to fix current and avoid future problems.
libbpf already uses the following prefixes for its interfaces:
* bpf_ for bpf system call wrappers, program/map/elf-object
abstractions and a few other things;
* btf_ for BTF related API;
* libbpf_ for everything else.
The patch adds libbpf_ prefix to interfaces in nlattr.h that use none of
mentioned above prefixes and doesn't fit well into the first two
categories.
Since affected part of API is used in bpftool, the patch applies
corresponding change to bpftool as well. Having it in a separate patch
will cause a state of tree where bpftool is broken what may not be a
good idea.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
libbpf is used more and more outside kernel tree. That means the library
should follow good practices in library design and implementation to
play well with third party code that uses it.
One of such practices is to have a common prefix (or a few) for every
interface, function or data structure, library provides. I helps to
avoid name conflicts with other libraries and keeps API consistent.
Inconsistent names in libbpf already cause problems in real life. E.g.
an application can't use both libbpf and libnl due to conflicting
symbols.
Having common prefix will help to fix current and avoid future problems.
libbpf already uses the following prefixes for its interfaces:
* bpf_ for bpf system call wrappers, program/map/elf-object
abstractions and a few other things;
* btf_ for BTF related API;
* libbpf_ for everything else.
The patch adds libbpf_ prefix to functions and typedef in libbpf.h that
use none of mentioned above prefixes and doesn't fit well into the first
two categories.
Since affected part of API is used in bpftool, the patch applies
corresponding change to bpftool as well. Having it in a separate patch
will cause a state of tree where bpftool is broken what may not be a
good idea.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This typedef is used only by implementation in netlink.c. Nothing uses
it in public API. Move it to netlink.c.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Use newly introduced libbpf_attach_type_by_name in test_socket_cookie
selftest.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add section names for BPF_SK_SKB_STREAM_PARSER and
BPF_SK_SKB_STREAM_VERDICT attach types to be able to identify them in
libbpf_attach_type_by_name.
"stream_parser" and "stream_verdict" are used instead of simple "parser"
and "verdict" just to avoid possible confusion in a place where attach
type is used alone (e.g. in bpftool's show sub-commands) since there is
another attach point that can be named as "verdict": BPF_SK_MSG_VERDICT.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add section names for BPF_CGROUP_INET_INGRESS and BPF_CGROUP_INET_EGRESS
attach types to be able to identify them in libbpf_attach_type_by_name.
"cgroup_skb" is used instead of "cgroup/skb" mostly to easy possible
unifying of how libbpf and bpftool works with section names:
* bpftool uses "cgroup_skb" to in "prog list" sub-command;
* bpftool uses "ingress" and "egress" in "cgroup list" sub-command;
* having two parts instead of three in a string like "cgroup_skb/ingress"
can be leveraged to split it to prog_type part and attach_type part,
or vise versa: use two parts to make a section name.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
There is a common use-case when ELF object contains multiple BPF
programs and every program has its own section name. If it's cgroup-bpf
then programs have to be 1) loaded and 2) attached to a cgroup.
It's convenient to have information necessary to load BPF program
together with program itself. This is where section name works fine in
conjunction with libbpf_prog_type_by_name that identifies prog_type and
expected_attach_type and these can be used with BPF_PROG_LOAD.
But there is currently no way to identify attach_type by section name
and it leads to messy code in user space that reinvents guessing logic
every time it has to identify attach type to use with BPF_PROG_ATTACH.
The patch introduces libbpf_attach_type_by_name that guesses attach type
by section name if a program can be attached.
The difference between expected_attach_type provided by
libbpf_prog_type_by_name and attach_type provided by
libbpf_attach_type_by_name is the former is used at BPF_PROG_LOAD time
and can be zero if a program of prog_type X has only one corresponding
attach type Y whether the latter provides specific attach type to use
with BPF_PROG_ATTACH.
No new section names were added to section_names array. Only existing
ones were reorganized and attach_type was added where appropriate.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Print `bpftool net` output to stdout instead of stderr. Only errors
should be printed to stderr. Regular output should go to stdout and this
is what all other subcommands of bpftool do, including --json and
--pretty formats of `bpftool net` itself.
Fixes: commit f6f3bac08f ("tools/bpf: bpftool: add net support")
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add selftests for bpf_skb_ancestor_cgroup_id helper.
test_skb_cgroup_id.sh prepares testing interface and adds tc qdisc and
filter for it using BPF object compiled from test_skb_cgroup_id_kern.c
program.
BPF program in test_skb_cgroup_id_kern.c gets ancestor cgroup id using
the new helper at different levels of cgroup hierarchy that skb belongs
to, including root level and non-existing level, and saves it to the map
where the key is the level of corresponding cgroup and the value is its
id.
To trigger BPF program, user space program test_skb_cgroup_id_user is
run. It adds itself into testing cgroup and sends UDP datagram to
link-local multicast address of testing interface. Then it reads cgroup
ids saved in kernel for different levels from the BPF map and compares
them with those in user space. They must be equal for every level of
ancestry.
Example of run:
# ./test_skb_cgroup_id.sh
Wait for testing link-local IP to become available ... OK
Note: 8 bytes struct bpf_elf_map fixup performed due to size mismatch!
[PASS]
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add bpf_skb_cgroup_id and bpf_skb_ancestor_cgroup_id helpers to
bpf_helpers.h to use them in tests and samples.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
== Problem description ==
It's useful to be able to identify cgroup associated with skb in TC so
that a policy can be applied to this skb, and existing bpf_skb_cgroup_id
helper can help with this.
Though in real life cgroup hierarchy and hierarchy to apply a policy to
don't map 1:1.
It's often the case that there is a container and corresponding cgroup,
but there are many more sub-cgroups inside container, e.g. because it's
delegated to containerized application to control resources for its
subsystems, or to separate application inside container from infra that
belongs to containerization system (e.g. sshd).
At the same time it may be useful to apply a policy to container as a
whole.
If multiple containers like this are run on a host (what is often the
case) and many of them have sub-cgroups, it may not be possible to apply
per-container policy in TC with existing helpers such as
bpf_skb_under_cgroup or bpf_skb_cgroup_id:
* bpf_skb_cgroup_id will return id of immediate cgroup associated with
skb, i.e. if it's a sub-cgroup inside container, it can't be used to
identify container's cgroup;
* bpf_skb_under_cgroup can work only with one cgroup and doesn't scale,
i.e. if there are N containers on a host and a policy has to be
applied to M of them (0 <= M <= N), it'd require M calls to
bpf_skb_under_cgroup, and, if M changes, it'd require to rebuild &
load new BPF program.
== Solution ==
The patch introduces new helper bpf_skb_ancestor_cgroup_id that can be
used to get id of cgroup v2 that is an ancestor of cgroup associated
with skb at specified level of cgroup hierarchy.
That way admin can place all containers on one level of cgroup hierarchy
(what is a good practice in general and already used in many
configurations) and identify specific cgroup on this level no matter
what sub-cgroup skb is associated with.
E.g. if there is a cgroup hierarchy:
root/
root/container1/
root/container1/app11/
root/container1/app11/sub-app-a/
root/container1/app12/
root/container2/
root/container2/app21/
root/container2/app22/
root/container2/app22/sub-app-b/
, then having skb associated with root/container1/app11/sub-app-a/ it's
possible to get ancestor at level 1, what is container1 and apply policy
for this container, or apply another policy if it's container2.
Policies can be kept e.g. in a hash map where key is a container cgroup
id and value is an action.
Levels where container cgroups are created are usually known in advance
whether cgroup hierarchy inside container may be hard to predict
especially in case when its creation is delegated to containerized
application.
== Implementation details ==
The helper gets ancestor by walking parents up to specified level.
Another option would be to get different kind of "id" from
cgroup->ancestor_ids[level] and use it with idr_find() to get struct
cgroup for ancestor. But that would require radix lookup what doesn't
seem to be better (at least it's not obviously better).
Format of return value of the new helper is same as that of
bpf_skb_cgroup_id.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add test to use get_socket_cookie() from BPF programs of types
BPF_PROG_TYPE_SOCK_OPS and BPF_PROG_TYPE_CGROUP_SOCK_ADDR.
The test attaches two programs to cgroup, runs TCP server and client in
the cgroup and checks that two operations are done properly on client
socket when user calls connect(2):
1. In BPF_CGROUP_INET6_CONNECT socket cookie is used as the key to write
new value in a map for client socket.
2. In BPF_CGROUP_SOCK_OPS (BPF_SOCK_OPS_TCP_CONNECT_CB callback) the
value written in "1." is found by socket cookie, since it's the same
socket, and updated.
Finally the test verifies the value in the map.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add missing helper to bpf_helpers.h that is used in tests and samples.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Sync bpf_get_socket_cookie() related bpf UAPI changes to tools/.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
bpf_get_socket_cookie() helper can be used to identify skb that
correspond to the same socket.
Though socket cookie can be useful in many other use-cases where socket is
available in program context. Specifically BPF_PROG_TYPE_CGROUP_SOCK_ADDR
and BPF_PROG_TYPE_SOCK_OPS programs can benefit from it so that one of
them can augment a value in a map prepared earlier by other program for
the same socket.
The patch adds support to call bpf_get_socket_cookie() from
BPF_PROG_TYPE_CGROUP_SOCK_ADDR and BPF_PROG_TYPE_SOCK_OPS.
It doesn't introduce new helpers. Instead it reuses same helper name
bpf_get_socket_cookie() but adds support to this helper to accept
`struct bpf_sock_addr` and `struct bpf_sock_ops`.
Documentation in bpf.h is changed in a way that should not break
automatic generation of markdown.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cover new TCP-BPF callback in test_tcpbpf: when listen() is called on
socket, set BPF_SOCK_OPS_STATE_CB_FLAG so that BPF_SOCK_OPS_STATE_CB
callback can be called on future state transition, and when such a
transition happens (TCP_LISTEN -> TCP_CLOSE), track it in the map and
verify it in user space later.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reduce amount of copy/paste for debug info when result is verified in
the test and keep that info together with values being checked so that
they won't get out of sync.
It also improves debug experience: instead of checking manually what
doesn't match in debug output for all fields, only unexpected field is
printed.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Switch to cgroup_helpers to simplify the code and fix cgroup cleanup:
before cgroup was not cleaned up after the test.
It also removes SYSTEM macro, that only printed error, but didn't
terminate the test.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add new TCP-BPF callback that is called on listen(2) right after socket
transition to TCP_LISTEN state.
It fills the gap for listening sockets in TCP-BPF. For example BPF
program can set BPF_SOCK_OPS_STATE_CB_FLAG when socket becomes listening
and track later transition from TCP_LISTEN to TCP_CLOSE with
BPF_SOCK_OPS_STATE_CB callback.
Before there was no way to do it with TCP-BPF and other options were
much harder to work with. E.g. socket state tracking can be done with
tracepoints (either raw or regular) but they can't be attached to cgroup
and their lifetime has to be managed separately.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
TCP Fast Open is triggered by sys_sendmsg with MSG_FASTOPEN flag for
SOCK_STREAM socket.
Even though it's sys_sendmsg, it eventually calls __inet_stream_connect
the same way sys_connect does for TCP. __inet_stream_connect, in turn,
already has BPF hooks for sys_connect.
That means TFO is already covered by BPF_CGROUP_INET{4,6}_CONNECT and
the only missing piece is selftest. The patch adds selftest for TFO.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add support for recently added BPF_CGROUP_UDP4_SENDMSG and
BPF_CGROUP_UDP6_SENDMSG attach types to bpftool, update documentation
and bash completion.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add selftest for BPF_CGROUP_UDP4_SENDMSG and BPF_CGROUP_UDP6_SENDMSG
attach types.
Try to sendmsg(2) to specific IP:port and test that:
* source IP is overridden as expected.
* remote IP:port pair is overridden as expected;
Both UDPv4 and UDPv6 are tested.
Output:
# test_sock_addr.sh 2>/dev/null
Wait for testing IPv4/IPv6 to become available ... OK
... pre-existing test-cases skipped ...
Test case: sendmsg4: load prog with wrong expected attach type .. [PASS]
Test case: sendmsg4: attach prog with wrong attach type .. [PASS]
Test case: sendmsg4: rewrite IP & port (asm) .. [PASS]
Test case: sendmsg4: rewrite IP & port (C) .. [PASS]
Test case: sendmsg4: deny call .. [PASS]
Test case: sendmsg6: load prog with wrong expected attach type .. [PASS]
Test case: sendmsg6: attach prog with wrong attach type .. [PASS]
Test case: sendmsg6: rewrite IP & port (asm) .. [PASS]
Test case: sendmsg6: rewrite IP & port (C) .. [PASS]
Test case: sendmsg6: IPv4-mapped IPv6 .. [PASS]
Test case: sendmsg6: deny call .. [PASS]
Summary: 27 PASSED, 0 FAILED
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
test_sock_addr was not easy to extend since it was focused on sys_bind
and sys_connect quite a bit.
Reorganized it so that it'll be easier to cover new test-cases for
`BPF_PROG_TYPE_CGROUP_SOCK_ADDR`:
- decouple test-cases so that only one BPF prog is tested at a time;
- check programmatically that local IP:port for sys_bind, source IP and
destination IP:port for sys_connect are rewritten property by tested
BPF programs.
The output of new version:
# test_sock_addr.sh 2>/dev/null
Wait for testing IPv4/IPv6 to become available ... OK
Test case: bind4: load prog with wrong expected attach type .. [PASS]
Test case: bind4: attach prog with wrong attach type .. [PASS]
Test case: bind4: rewrite IP & TCP port in .. [PASS]
Test case: bind4: rewrite IP & UDP port in .. [PASS]
Test case: bind6: load prog with wrong expected attach type .. [PASS]
Test case: bind6: attach prog with wrong attach type .. [PASS]
Test case: bind6: rewrite IP & TCP port in .. [PASS]
Test case: bind6: rewrite IP & UDP port in .. [PASS]
Test case: connect4: load prog with wrong expected attach type .. [PASS]
Test case: connect4: attach prog with wrong attach type .. [PASS]
Test case: connect4: rewrite IP & TCP port .. [PASS]
Test case: connect4: rewrite IP & UDP port .. [PASS]
Test case: connect6: load prog with wrong expected attach type .. [PASS]
Test case: connect6: attach prog with wrong attach type .. [PASS]
Test case: connect6: rewrite IP & TCP port .. [PASS]
Test case: connect6: rewrite IP & UDP port .. [PASS]
Summary: 16 PASSED, 0 FAILED
(stderr contains errors from libbpf when testing load/attach with
invalid arguments)
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
libbpf can guess prog type and expected attach type based on section
name. Add hints for "cgroup/sendmsg4" and "cgroup/sendmsg6" section
names.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Sync new `BPF_CGROUP_UDP4_SENDMSG` and `BPF_CGROUP_UDP6_SENDMSG`
attach types to tools/.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
In addition to already existing BPF hooks for sys_bind and sys_connect,
the patch provides new hooks for sys_sendmsg.
It leverages existing BPF program type `BPF_PROG_TYPE_CGROUP_SOCK_ADDR`
that provides access to socket itlself (properties like family, type,
protocol) and user-passed `struct sockaddr *` so that BPF program can
override destination IP and port for system calls such as sendto(2) or
sendmsg(2) and/or assign source IP to the socket.
The hooks are implemented as two new attach types:
`BPF_CGROUP_UDP4_SENDMSG` and `BPF_CGROUP_UDP6_SENDMSG` for UDPv4 and
UDPv6 correspondingly.
UDPv4 and UDPv6 separate attach types for same reason as sys_bind and
sys_connect hooks, i.e. to prevent reading from / writing to e.g.
user_ip6 fields when user passes sockaddr_in since it'd be out-of-bound.
The difference with already existing hooks is sys_sendmsg are
implemented only for unconnected UDP.
For TCP it doesn't make sense to change user-provided `struct sockaddr *`
at sendto(2)/sendmsg(2) time since socket either was already connected
and has source/destination set or wasn't connected and call to
sendto(2)/sendmsg(2) would lead to ENOTCONN anyway.
Connected UDP is already handled by sys_connect hooks that can override
source/destination at connect time and use fast-path later, i.e. these
hooks don't affect UDP fast-path.
Rewriting source IP is implemented differently than that in sys_connect
hooks. When sys_sendmsg is used with unconnected UDP it doesn't work to
just bind socket to desired local IP address since source IP can be set
on per-packet basis by using ancillary data (cmsg(3)). So no matter if
socket is bound or not, source IP has to be rewritten on every call to
sys_sendmsg.
To do so two new fields are added to UAPI `struct bpf_sock_addr`;
* `msg_src_ip4` to set source IPv4 for UDPv4;
* `msg_src_ip6` to set source IPv6 for UDPv6.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Static key is used to enable/disable cgroup-bpf related code paths at
run time.
Though it's not defined when cgroup-bpf is disabled at compile time,
i.e. CONFIG_CGROUP_BPF=n, and if some code wants to use it, it has to do
this:
#ifdef CONFIG_CGROUP_BPF
if (cgroup_bpf_enabled) {
/* ... some work ... */
}
#endif
This code can be simplified by setting cgroup_bpf_enabled to 0 for
CONFIG_CGROUP_BPF=n case:
if (cgroup_bpf_enabled) {
/* ... some work ... */
}
And it aligns well with existing BPF_CGROUP_RUN_PROG_* macros that
defined for both states of CONFIG_CGROUP_BPF.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
install_headers target should contain all headers that are part of
libbpf. Add missing btf.h
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Fix more memory leaks in ip_cmsg_send() callers. Part of them were fixed
earlier in 919483096b.
* udp_sendmsg one was there since the beginning when linux sources were
first added to git;
* ping_v4_sendmsg one was copy/pasted in c319b4d76b.
Whenever return happens in udp_sendmsg() or ping_v4_sendmsg() IP options
have to be freed if they were allocated previously.
Add label so that future callers (if any) can use it instead of kfree()
before return that is easy to forget.
Fixes: c319b4d76b (net: ipv4: add IPPROTO_ICMP socket kind)
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Helpers may operate on two types of ctx structures: user visible ones
(e.g. `struct bpf_sock_ops`) when used in user programs, and kernel ones
(e.g. `struct bpf_sock_ops_kern`) in kernel implementation.
UAPI documentation must refer to only user visible structures.
The patch replaces references to `_kern` structures in BPF helpers
description by corresponding user visible structures.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add missing pieces for BPF_PROG_TYPE_RAW_TRACEPOINT in libbpf:
* is- and set- functions;
* support guessing prog type.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
libbpf can guess prog type and expected attach type based on section
name. Add hints for "cgroup/post_bind4" and "cgroup/post_bind6" section
names.
Existing "cgroup/sock" is not changed, i.e. expected_attach_type for it
is not set to `BPF_CGROUP_INET_SOCK_CREATE`, for backward compatibility.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This tracepoint was replaced by inet_sock_set_state in 563e0bb and not
used anywhere in the kernel anymore. Remove it.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add selftest for attach types `BPF_CGROUP_INET4_POST_BIND` and
`BPF_CGROUP_INET6_POST_BIND`.
The main things tested are:
* prog load behaves as expected (valid/invalid accesses in prog);
* prog attach behaves as expected (load- vs attach-time attach types);
* `BPF_CGROUP_INET_SOCK_CREATE` can be attached in a backward compatible
way;
* post-hooks return expected result and errno.
Example:
# ./test_sock
Test case: bind4 load with invalid access: src_ip6 .. [PASS]
Test case: bind4 load with invalid access: mark .. [PASS]
Test case: bind6 load with invalid access: src_ip4 .. [PASS]
Test case: sock_create load with invalid access: src_port .. [PASS]
Test case: sock_create load w/o expected_attach_type (compat mode) ..
[PASS]
Test case: sock_create load w/ expected_attach_type .. [PASS]
Test case: attach type mismatch bind4 vs bind6 .. [PASS]
Test case: attach type mismatch bind6 vs bind4 .. [PASS]
Test case: attach type mismatch default vs bind4 .. [PASS]
Test case: attach type mismatch bind6 vs sock_create .. [PASS]
Test case: bind4 reject all .. [PASS]
Test case: bind6 reject all .. [PASS]
Test case: bind6 deny specific IP & port .. [PASS]
Test case: bind4 allow specific IP & port .. [PASS]
Test case: bind4 allow all .. [PASS]
Test case: bind6 allow all .. [PASS]
Summary: 16 PASSED, 0 FAILED
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
"Post-hooks" are hooks that are called right before returning from
sys_bind. At this time IP and port are already allocated and no further
changes to `struct sock` can happen before returning from sys_bind but
BPF program has a chance to inspect the socket and change sys_bind
result.
Specifically it can e.g. inspect what port was allocated and if it
doesn't satisfy some policy, BPF program can force sys_bind to fail and
return EPERM to user.
Another example of usage is recording the IP:port pair to some map to
use it in later calls to sys_connect. E.g. if some TCP server inside
cgroup was bound to some IP:port_n, it can be recorded to a map. And
later when some TCP client inside same cgroup is trying to connect to
127.0.0.1:port_n, BPF hook for sys_connect can override the destination
and connect application to IP:port_n instead of 127.0.0.1:port_n. That
helps forcing all applications inside a cgroup to use desired IP and not
break those applications if they e.g. use localhost to communicate
between each other.
== Implementation details ==
Post-hooks are implemented as two new attach types
`BPF_CGROUP_INET4_POST_BIND` and `BPF_CGROUP_INET6_POST_BIND` for
existing prog type `BPF_PROG_TYPE_CGROUP_SOCK`.
Separate attach types for IPv4 and IPv6 are introduced to avoid access
to IPv6 field in `struct sock` from `inet_bind()` and to IPv4 field from
`inet6_bind()` since those fields might not make sense in such cases.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
== The problem ==
See description of the problem in the initial patch of this patch set.
== The solution ==
The patch provides much more reliable in-kernel solution for the 2nd
part of the problem: making outgoing connecttion from desired IP.
It adds new attach types `BPF_CGROUP_INET4_CONNECT` and
`BPF_CGROUP_INET6_CONNECT` for program type
`BPF_PROG_TYPE_CGROUP_SOCK_ADDR` that can be used to override both
source and destination of a connection at connect(2) time.
Local end of connection can be bound to desired IP using newly
introduced BPF-helper `bpf_bind()`. It allows to bind to only IP though,
and doesn't support binding to port, i.e. leverages
`IP_BIND_ADDRESS_NO_PORT` socket option. There are two reasons for this:
* looking for a free port is expensive and can affect performance
significantly;
* there is no use-case for port.
As for remote end (`struct sockaddr *` passed by user), both parts of it
can be overridden, remote IP and remote port. It's useful if an
application inside cgroup wants to connect to another application inside
same cgroup or to itself, but knows nothing about IP assigned to the
cgroup.
Support is added for IPv4 and IPv6, for TCP and UDP.
IPv4 and IPv6 have separate attach types for same reason as sys_bind
hooks, i.e. to prevent reading from / writing to e.g. user_ip6 fields
when user passes sockaddr_in since it'd be out-of-bound.
== Implementation notes ==
The patch introduces new field in `struct proto`: `pre_connect` that is
a pointer to a function with same signature as `connect` but is called
before it. The reason is in some cases BPF hooks should be called way
before control is passed to `sk->sk_prot->connect`. Specifically
`inet_dgram_connect` autobinds socket before calling
`sk->sk_prot->connect` and there is no way to call `bpf_bind()` from
hooks from e.g. `ip4_datagram_connect` or `ip6_datagram_connect` since
it'd cause double-bind. On the other hand `proto.pre_connect` provides a
flexible way to add BPF hooks for connect only for necessary `proto` and
call them at desired time before `connect`. Since `bpf_bind()` is
allowed to bind only to IP and autobind in `inet_dgram_connect` binds
only port there is no chance of double-bind.
bpf_bind() sets `force_bind_address_no_port` to bind to only IP despite
of value of `bind_address_no_port` socket field.
bpf_bind() sets `with_lock` to `false` when calling to __inet_bind()
and __inet6_bind() since all call-sites, where bpf_bind() is called,
already hold socket lock.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Andrey Ignatov