Simplify tcp_set_congestion_control() by removing the initialization
code path for the !load case.
There are only two call sites for tcp_set_congestion_control(). The
EBPF call site is the only one that passes load=false; it also passes
cap_net_admin=true. Because of that, the exact same behavior can be
achieved by removing the special if (!load) branch of the logic. Both
before and after this commit, the EBPF case will call
bpf_try_module_get(), and if that succeeds then call
tcp_reinit_congestion_control() or if that fails then return EBUSY.
Note that this returns the logic to a structure very similar to the
structure before:
commit 91b5b21c7c ("bpf: Add support for changing congestion control")
except that the CAP_NET_ADMIN status is passed in as a function
argument.
This clean-up was suggested by Martin KaFai Lau.
Suggested-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: Lawrence Brakmo <brakmo@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Kevin Yang <yyd@google.com>
Now that the previous patches have removed the code that uses the
flags argument to _bpf_setsockopt(), we can remove that argument.
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Kevin Yang <yyd@google.com>
Cc: Lawrence Brakmo <brakmo@fb.com>
Now that the previous patches ensure that all call sites for
tcp_set_congestion_control() want to initialize congestion control, we
can simplify tcp_set_congestion_control() by removing the reinit
argument and the code to support it.
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Kevin Yang <yyd@google.com>
Cc: Lawrence Brakmo <brakmo@fb.com>
Now that the previous patch ensures we don't initialize the congestion
control twice, when EBPF sets the congestion control algorithm at
connection establishment we can simplify the code by simply
initializing the congestion control module at that time.
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Kevin Yang <yyd@google.com>
Cc: Lawrence Brakmo <brakmo@fb.com>
Change tcp_init_transfer() to only initialize congestion control if it
has not been initialized already.
With this new approach, we can arrange things so that if the EBPF code
sets the congestion control by calling setsockopt(TCP_CONGESTION) then
tcp_init_transfer() will not re-initialize the CC module.
This is an approach that has the following beneficial properties:
(1) This allows CC module customizations made by the EBPF called in
tcp_init_transfer() to persist, and not be wiped out by a later
call to tcp_init_congestion_control() in tcp_init_transfer().
(2) Does not flip the order of EBPF and CC init, to avoid causing bugs
for existing code upstream that depends on the current order.
(3) Does not cause 2 initializations for for CC in the case where the
EBPF called in tcp_init_transfer() wants to set the CC to a new CC
algorithm.
(4) Allows follow-on simplifications to the code in net/core/filter.c
and net/ipv4/tcp_cong.c, which currently both have some complexity
to special-case CC initialization to avoid double CC
initialization if EBPF sets the CC.
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Kevin Yang <yyd@google.com>
Cc: Lawrence Brakmo <brakmo@fb.com>
The "SEE ALSO" sections of bpftool's manual pages refer to bpf(2),
bpf-helpers(7), then all existing bpftool man pages (save the current
one).
This leads to nearly-identical lists being duplicated in all manual
pages. Ideally, when a new page is created, all lists should be updated
accordingly, but this has led to omissions and inconsistencies multiple
times in the past.
Let's take it out of the RST files and generate the "SEE ALSO" sections
automatically in the Makefile when generating the man pages. The lists
are not really useful in the RST anyway because all other pages are
available in the same directory.
v3:
- Fix conflict with a previous patchset that introduced RST2MAN_OPTS
variable passed to rst2man.
v2:
- Use "echo -n" instead of "printf" in Makefile, to avoid any risk of
passing a format string directly to the command.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200910203935.25304-1-quentin@isovalent.com
When tweaking llvm optimizations, I found that selftest build failed
with the following error:
libbpf: elf: skipping unrecognized data section(6) .rodata.str1.1
libbpf: prog 'sysctl_tcp_mem': bad map relo against '.L__const.is_tcp_mem.tcp_mem_name'
in section '.rodata.str1.1'
Error: failed to open BPF object file: Relocation failed
make: *** [/work/net-next/tools/testing/selftests/bpf/test_sysctl_prog.skel.h] Error 255
make: *** Deleting file `/work/net-next/tools/testing/selftests/bpf/test_sysctl_prog.skel.h'
The local string constant "tcp_mem_name" is put into '.rodata.str1.1' section
which libbpf cannot handle. Using untweaked upstream llvm, "tcp_mem_name"
is completely inlined after loop unrolling.
Commit 7fb5eefd76 ("selftests/bpf: Fix test_sysctl_loop{1, 2}
failure due to clang change") solved a similar problem by defining
the string const as a global. Let us do the same here
for test_sysctl_prog.c so it can weather future potential llvm changes.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200910202718.956042-1-yhs@fb.com
On non-SMP kernels __per_cpu_start is not 0, so look it up in kallsyms.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200910171336.3161995-1-iii@linux.ibm.com
There is no support for creating maps of types array-of-map or
hash-of-map in bpftool. This is because the kernel needs an inner_map_fd
to collect metadata on the inner maps to be supported by the new map,
but bpftool does not provide a way to pass this file descriptor.
Add a new optional "inner_map" keyword that can be used to pass a
reference to a map, retrieve a fd to that map, and pass it as the
inner_map_fd.
Add related documentation and bash completion. Note that we can
reference the inner map by its name, meaning we can have several times
the keyword "name" with different meanings (mandatory outer map name,
and possibly a name to use to find the inner_map_fd). The bash
completion will offer it just once, and will not suggest "name" on the
following command:
# bpftool map create /sys/fs/bpf/my_outer_map type hash_of_maps \
inner_map name my_inner_map [TAB]
Fixing that specific case seems too convoluted. Completion will work as
expected, however, if the outer map name comes first and the "inner_map
name ..." is passed second.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200910102652.10509-4-quentin@isovalent.com
When dumping outer maps or prog_array maps, and on lookup failure,
bpftool simply skips the entry with no error message. This is because
the kernel returns non-zero when no value is found for the provided key,
which frequently happen for those maps if they have not been filled.
When such a case occurs, errno is set to ENOENT. It seems unlikely we
could receive other error codes at this stage (we successfully retrieved
map info just before), but to be on the safe side, let's skip the entry
only if errno was ENOENT, and not for the other errors.
v3: New patch
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200910102652.10509-3-quentin@isovalent.com
The function used to dump a map entry in bpftool is a bit difficult to
follow, as a consequence to earlier refactorings. There is a variable
("num_elems") which does not appear to be necessary, and the error
handling would look cleaner if moved to its own function. Let's clean it
up. No functional change.
v2:
- v1 was erroneously removing the check on fd maps in an attempt to get
support for outer map dumps. This is already working. Instead, v2
focuses on cleaning up the dump_map_elem() function, to avoid
similar confusion in the future.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200910102652.10509-2-quentin@isovalent.com
Add a test that exercises a basic sockmap / sockhash iteration. For
now we simply count the number of elements seen. Once sockmap update
from iterators works we can extend this to perform a full copy.
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200909162712.221874-4-lmb@cloudflare.com
Add bpf_iter support for sockmap / sockhash, based on the bpf_sk_storage and
hashtable implementation. sockmap and sockhash share the same iteration
context: a pointer to an arbitrary key and a pointer to a socket. Both
pointers may be NULL, and so BPF has to perform a NULL check before accessing
them. Technically it's not possible for sockhash iteration to yield a NULL
socket, but we ignore this to be able to use a single iteration point.
Iteration will visit all keys that remain unmodified during the lifetime of
the iterator. It may or may not visit newly added ones.
Switch from using rcu_dereference_raw to plain rcu_dereference, so we gain
another guard rail if CONFIG_PROVE_RCU is enabled.
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200909162712.221874-3-lmb@cloudflare.com
The lookup paths for sockmap and sockhash currently include a check
that returns NULL if the socket we just found is not a full socket.
However, this check is not necessary. On insertion we ensure that
we have a full socket (caveat around sock_ops), so request sockets
are not a problem. Time-wait sockets are allocated separate from
the original socket and then fed into the hashdance. They don't
affect the sockets already stored in the sockmap.
Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200909162712.221874-2-lmb@cloudflare.com
Nearly all man pages for bpftool have the same common set of option
flags (--help, --version, --json, --pretty, --debug). The description is
duplicated across all the pages, which is more difficult to maintain if
the description of an option changes. It may also be confusing to sort
out what options are not "common" and should not be copied when creating
new manual pages.
Let's move the description for those common options to a separate file,
which is included with a RST directive when generating the man pages.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200909162500.17010-3-quentin@isovalent.com
Bpftool has a number of features that can be included or left aside
during compilation. This includes:
- Support for libbfd, providing the disassembler for JIT-compiled
programs.
- Support for BPF skeletons, used for profiling programs or iterating on
the PIDs of processes associated with BPF objects.
In order to make it easy for users to understand what features were
compiled for a given bpftool binary, print the status of the two
features above when showing the version number for bpftool ("bpftool -V"
or "bpftool version"). Document this in the main manual page. Example
invocations:
$ bpftool version
./bpftool v5.9.0-rc1
features: libbfd, skeletons
$ bpftool -p version
{
"version": "5.9.0-rc1",
"features": {
"libbfd": true,
"skeletons": true
}
}
Some other parameters are optional at compilation
("DISASM_FOUR_ARGS_SIGNATURE", LIBCAP support) but they do not impact
significantly bpftool's behaviour from a user's point of view, so their
status is not reported.
Available commands and supported program types depend on the version
number, and are therefore not reported either. Note that they are
already available, albeit without JSON, via bpftool's help messages.
v3:
- Use a simple list instead of boolean values for plain output.
v2:
- Fix JSON (object instead or array for the features).
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200909162500.17010-2-quentin@isovalent.com
eBPF selftests include a script to check that bpftool builds correctly
with different command lines. Let's add one build for bpftool's
documentation so as to detect errors or warning reported by rst2man when
compiling the man pages. Also add a build to the selftests Makefile to
make sure we build bpftool documentation along with bpftool when
building the selftests.
This also builds and checks warnings for the man page for eBPF helpers,
which is built along bpftool's documentation.
This change adds rst2man as a dependency for selftests (it comes with
Python's "docutils").
v2:
- Use "--exit-status=1" option for rst2man instead of counting lines
from stderr.
- Also build bpftool as part as the selftests build (and not only when
the tests are actually run).
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200909162251.15498-3-quentin@isovalent.com
To build man pages for bpftool (and for eBPF helper functions), rst2man
can log different levels of information. Let's make it log all levels
to keep the RST files clean.
Doing so, rst2man complains about double colons, used for literal
blocks, that look like underlines for section titles. Let's add the
necessary blank lines.
v2:
- Use "--verbose" instead of "-r 1" (same behaviour but more readable).
- Pass it through a RST2MAN_OPTS variable so we can easily pass other
options too.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200909162251.15498-2-quentin@isovalent.com
Switch from deprecated bpf_program__title() API to
bpf_program__section_name(). Also drop unnecessary error checks because
neither bpf_program__title() nor bpf_program__section_name() can fail or
return NULL.
Fixes: 5210958420 ("libbpf: Deprecate notion of BPF program "title" in favor of "section name"")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/bpf/20200908180127.1249-1-andriin@fb.com
Andrii reported that with latest clang, when building selftests, we have
error likes:
error: progs/test_sysctl_loop1.c:23:16: in function sysctl_tcp_mem i32 (%struct.bpf_sysctl*):
Looks like the BPF stack limit of 512 bytes is exceeded.
Please move large on stack variables into BPF per-cpu array map.
The error is triggered by the following LLVM patch:
https://reviews.llvm.org/D87134
For example, the following code is from test_sysctl_loop1.c:
static __always_inline int is_tcp_mem(struct bpf_sysctl *ctx)
{
volatile char tcp_mem_name[] = "net/ipv4/tcp_mem/very_very_very_very_long_pointless_string";
...
}
Without the above LLVM patch, the compiler did optimization to load the string
(59 bytes long) with 7 64bit loads, 1 8bit load and 1 16bit load,
occupying 64 byte stack size.
With the above LLVM patch, the compiler only uses 8bit loads, but subregister is 32bit.
So stack requirements become 4 * 59 = 236 bytes. Together with other stuff on
the stack, total stack size exceeds 512 bytes, hence compiler complains and quits.
To fix the issue, removing "volatile" key word or changing "volatile" to
"const"/"static const" does not work, the string is put in .rodata.str1.1 section,
which libbpf did not process it and errors out with
libbpf: elf: skipping unrecognized data section(6) .rodata.str1.1
libbpf: prog 'sysctl_tcp_mem': bad map relo against '.L__const.is_tcp_mem.tcp_mem_name'
in section '.rodata.str1.1'
Defining the string const as global variable can fix the issue as it puts the string constant
in '.rodata' section which is recognized by libbpf. In the future, when libbpf can process
'.rodata.str*.*' properly, the global definition can be changed back to local definition.
Defining tcp_mem_name as a global, however, triggered a verifier failure.
./test_progs -n 7/21
libbpf: load bpf program failed: Permission denied
libbpf: -- BEGIN DUMP LOG ---
libbpf:
invalid stack off=0 size=1
verification time 6975 usec
stack depth 160+64
processed 889 insns (limit 1000000) max_states_per_insn 4 total_states
14 peak_states 14 mark_read 10
libbpf: -- END LOG --
libbpf: failed to load program 'sysctl_tcp_mem'
libbpf: failed to load object 'test_sysctl_loop2.o'
test_bpf_verif_scale:FAIL:114
#7/21 test_sysctl_loop2.o:FAIL
This actually exposed a bpf program bug. In test_sysctl_loop{1,2}, we have code
like
const char tcp_mem_name[] = "<...long string...>";
...
char name[64];
...
for (i = 0; i < sizeof(tcp_mem_name); ++i)
if (name[i] != tcp_mem_name[i])
return 0;
In the above code, if sizeof(tcp_mem_name) > 64, name[i] access may be
out of bound. The sizeof(tcp_mem_name) is 59 for test_sysctl_loop1.c and
79 for test_sysctl_loop2.c.
Without promotion-to-global change, old compiler generates code where
the overflowed stack access is actually filled with valid value, so hiding
the bpf program bug. With promotion-to-global change, the code is different,
more specifically, the previous loading constants to stack is gone, and
"name" occupies stack[-64:0] and overflow access triggers a verifier error.
To fix the issue, adjust "name" buffer size properly.
Reported-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200909171542.3673449-1-yhs@fb.com
Change selftest map_ptr_kern.c with disabling inlining for
one of subtests, which will fail the test without previous
verifier change. Also added to verifier test for both
"map_ptr += scalar" and "scalar += map_ptr" arithmetic.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200908175703.2463721-1-yhs@fb.com
Commit 41c48f3a98 ("bpf: Support access
to bpf map fields") added support to access map fields
with CORE support. For example,
struct bpf_map {
__u32 max_entries;
} __attribute__((preserve_access_index));
struct bpf_array {
struct bpf_map map;
__u32 elem_size;
} __attribute__((preserve_access_index));
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 4);
__type(key, __u32);
__type(value, __u32);
} m_array SEC(".maps");
SEC("cgroup_skb/egress")
int cg_skb(void *ctx)
{
struct bpf_array *array = (struct bpf_array *)&m_array;
/* .. array->map.max_entries .. */
}
In kernel, bpf_htab has similar structure,
struct bpf_htab {
struct bpf_map map;
...
}
In the above cg_skb(), to access array->map.max_entries, with CORE, the clang will
generate two builtin's.
base = &m_array;
/* access array.map */
map_addr = __builtin_preserve_struct_access_info(base, 0, 0);
/* access array.map.max_entries */
max_entries_addr = __builtin_preserve_struct_access_info(map_addr, 0, 0);
max_entries = *max_entries_addr;
In the current llvm, if two builtin's are in the same function or
in the same function after inlining, the compiler is smart enough to chain
them together and generates like below:
base = &m_array;
max_entries = *(base + reloc_offset); /* reloc_offset = 0 in this case */
and we are fine.
But if we force no inlining for one of functions in test_map_ptr() selftest, e.g.,
check_default(), the above two __builtin_preserve_* will be in two different
functions. In this case, we will have code like:
func check_hash():
reloc_offset_map = 0;
base = &m_array;
map_base = base + reloc_offset_map;
check_default(map_base, ...)
func check_default(map_base, ...):
max_entries = *(map_base + reloc_offset_max_entries);
In kernel, map_ptr (CONST_PTR_TO_MAP) does not allow any arithmetic.
The above "map_base = base + reloc_offset_map" will trigger a verifier failure.
; VERIFY(check_default(&hash->map, map));
0: (18) r7 = 0xffffb4fe8018a004
2: (b4) w1 = 110
3: (63) *(u32 *)(r7 +0) = r1
R1_w=invP110 R7_w=map_value(id=0,off=4,ks=4,vs=8,imm=0) R10=fp0
; VERIFY_TYPE(BPF_MAP_TYPE_HASH, check_hash);
4: (18) r1 = 0xffffb4fe8018a000
6: (b4) w2 = 1
7: (63) *(u32 *)(r1 +0) = r2
R1_w=map_value(id=0,off=0,ks=4,vs=8,imm=0) R2_w=invP1 R7_w=map_value(id=0,off=4,ks=4,vs=8,imm=0) R10=fp0
8: (b7) r2 = 0
9: (18) r8 = 0xffff90bcb500c000
11: (18) r1 = 0xffff90bcb500c000
13: (0f) r1 += r2
R1 pointer arithmetic on map_ptr prohibited
To fix the issue, let us permit map_ptr + 0 arithmetic which will
result in exactly the same map_ptr.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200908175702.2463625-1-yhs@fb.com
Synchronise the bpf.h header under tools, to report the fixes recently
brought to the documentation for the BPF helpers.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200904161454.31135-4-quentin@isovalent.com
Fix a formatting error in the description of bpf_load_hdr_opt() (rst2man
complains about a wrong indentation, but what is missing is actually a
blank line before the bullet list).
Fix and harmonise the formatting for other helpers.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200904161454.31135-3-quentin@isovalent.com
Fix a formatting error in the documentation for bpftool-link, so that
the man page can build correctly.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200904161454.31135-2-quentin@isovalent.com
From commit 5210958420 ("libbpf: Deprecate notion of BPF program
"title" in favor of "section name""), the term title has been replaced
with section name in libbpf.
Since the bpf_program__title() has been deprecated, this commit
switches this function to bpf_program__section_name(). Due to
this commit, the compilation warning issue has also been resolved.
Fixes: 5210958420 ("libbpf: Deprecate notion of BPF program "title" in favor of "section name"")
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200904063434.24963-1-danieltimlee@gmail.com
Detected by LGTM static analyze in Github repo, fix potential multiplication
overflow before result is casted to size_t.
Fixes: 8505e8709b ("libbpf: Implement generalized .BTF.ext func/line info adjustment")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200904041611.1695163-2-andriin@fb.com
Another issue of __u64 needing either %lu or %llu, depending on the
architecture. Fix with cast to `unsigned long long`.
Fixes: 7e06aad529 ("libbpf: Add multi-prog section support for struct_ops")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200904041611.1695163-1-andriin@fb.com
The returned value of bpf_object__open_file() should be checked with
libbpf_get_error() rather than NULL. This fix prevents test_progs from
crash when test_global_data.o is not present.
Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200903200528.747884-1-haoluo@google.com
Andrii Nakryiko says:
====================
Currently, libbpf supports a limited form of BPF-to-BPF subprogram calls. The
restriction is that entry-point BPF program should use *all* of defined
sub-programs in BPF .o file. If any of the subprograms is not used, such
entry-point BPF program will be rejected by verifier as containing unreachable
dead code. This is not a big limitation for cases with single entry-point BPF
programs, but is quite a heavy restriction for multi-programs that use only
partially overlapping set of subprograms.
This patch set removes all such restrictions and adds complete support for
using BPF sub-program calls on BPF side. This is achieved through libbpf
tracking subprograms individually and detecting which subprograms are used by
any given entry-point BPF program, and subsequently only appending and
relocating code for just those used subprograms.
In addition, libbpf now also supports multiple entry-point BPF programs within
the same ELF section. This allows to structure code so that there are few
variants of BPF programs of the same type and attaching to the same target
(e.g., for tracepoints and kprobes) without the need to worry about ELF
section name clashes.
This patch set opens way for more wider adoption of BPF subprogram calls,
especially for real-world production use-cases with complicated net of
subprograms. This will allow to further scale BPF verification process through
good use of global functions, which can be verified independently. This is
also important prerequisite for static linking which allows static BPF
libraries to not worry about naming clashes for section names, as well as use
static non-inlined functions (subprograms) without worries of verifier
rejecting program due to dead code.
Patch set is structured as follows:
- patched 1-6 contain all the libbpf changes necessary to support multi-prog
sections and bpf2bpf subcalls;
- patch 7 adds dedicated selftests validating all combinations of possible
sub-calls (within and across sections, static vs global functions);
- patch 8 deprecated bpf_program__title() in favor of
bpf_program__section_name(). The intent was to also deprecate
bpf_object__find_program_by_title() as it's now non-sensical with multiple
programs per section. But there were too many selftests uses of this and
I didn't want to delay this patches further and make it even bigger, so left
it for a follow up cleanup;
- patches 9-10 remove uses for title-related APIs from bpftool and
bpf_program__title() use from selftests;
- patch 11 is converting fexit_bpf2bpf to have explicit subtest (it does
contain 4 subtests, which are not handled as sub-tests);
- patches 12-14 convert few complicated BPF selftests to use __noinline
functions to further validate correctness of libbpf's bpf2bpf processing
logic.
v2->v3:
- explained subprog relocation algorithm in more details (Alexei);
- pyperf, strobelight and cls_redirect got new subprog variants, leaving
other modes intact (Alexei);
v1->v2:
- rename DEPRECATED to LIBBPF_DEPRECATED to avoid name clashes;
- fix test_subprogs build;
- convert a bunch of complicated selftests to __noinline (Alexei).
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
As one of the most complicated and close-to-real-world programs, cls_redirect
is a good candidate to exercise libbpf's logic of handling bpf2bpf calls. So
add variant with using explicit __noinline for majority of functions except
few most basic ones. If those few functions are inlined, verifier starts to
complain about program instruction limit of 1mln instructions being exceeded,
most probably due to instruction overhead of doing a sub-program call.
Convert user-space part of selftest to have to sub-tests: with and without
inlining.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: Lorenz Bauer <lmb@cloudflare.com>
Link: https://lore.kernel.org/bpf/20200903203542.15944-15-andriin@fb.com
Update xdp_noinline to use BPF skeleton and force __noinline on helper
sub-programs. Also, split existing logic into v4- and v6-only to complicate
sub-program calling patterns (partially overlapped sets of functions for
entry-level BPF programs).
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200903203542.15944-14-andriin@fb.com
Add use of non-inlined subprogs to few bigger selftests to excercise libbpf's
bpf2bpf handling logic. Also split l4lb_all selftest into two sub-tests.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200903203542.15944-13-andriin@fb.com
BPF program title is ambigious and misleading term. It is ELF section name, so
let's just call it that and deprecate bpf_program__title() API in favor of
bpf_program__section_name().
Additionally, using bpf_object__find_program_by_title() is now inherently
dangerous and ambiguous, as multiple BPF program can have the same section
name. So deprecate this API as well and recommend to switch to non-ambiguous
bpf_object__find_program_by_name().
Internally, clean up usage and mis-usage of BPF program section name for
denoting BPF program name. Shorten the field name to prog->sec_name to be
consistent with all other prog->sec_* variables.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200903203542.15944-11-andriin@fb.com
Add a selftest excercising bpf-to-bpf subprogram calls, as well as multiple
entry-point BPF programs per section. Also make sure that BPF CO-RE works for
such set ups both for sub-programs and for multi-entry sections.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200903203542.15944-8-andriin@fb.com
Complete multi-prog sections and multi sub-prog support in libbpf by properly
adjusting .BTF.ext's line and function information. Mark exposed
btf_ext__reloc_func_info() and btf_ext__reloc_func_info() APIs as deprecated.
These APIs have simplistic assumption that all sub-programs are going to be
appended to all main BPF programs, which doesn't hold in real life. It's
unlikely there are any users of this API, as it's very libbpf
internals-specific.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200903203542.15944-6-andriin@fb.com
This patch implements general and correct logic for bpf-to-bpf sub-program
calls. Only sub-programs used (called into) from entry-point (main) BPF
program are going to be appended at the end of main BPF program. This ensures
that BPF verifier won't encounter any dead code due to copying unreferenced
sub-program. This change means that each entry-point (main) BPF program might
have a different set of sub-programs appended to it and potentially in
different order. This has implications on how sub-program call relocations
need to be handled, described below.
All relocations are now split into two categores: data references (maps and
global variables) and code references (sub-program calls). This distinction is
important because data references need to be relocated just once per each BPF
program and sub-program. These relocation are agnostic to instruction
locations, because they are not code-relative and they are relocating against
static targets (maps, variables with fixes offsets, etc).
Sub-program RELO_CALL relocations, on the other hand, are highly-dependent on
code position, because they are recorded as instruction-relative offset. So
BPF sub-programs (those that do calls into other sub-programs) can't be
relocated once, they need to be relocated each time such a sub-program is
appended at the end of the main entry-point BPF program. As mentioned above,
each main BPF program might have different subset and differen order of
sub-programs, so call relocations can't be done just once. Splitting data
reference and calls relocations as described above allows to do this
efficiently and cleanly.
bpf_object__find_program_by_name() will now ignore non-entry BPF programs.
Previously one could have looked up '.text' fake BPF program, but the
existence of such BPF program was always an implementation detail and you
can't do much useful with it. Now, though, all non-entry sub-programs get
their own BPF program with name corresponding to a function name, so there is
no more '.text' name for BPF program. This means there is no regression,
effectively, w.r.t. API behavior. But this is important aspect to highlight,
because it's going to be critical once libbpf implements static linking of BPF
programs. Non-entry static BPF programs will be allowed to have conflicting
names, but global and main-entry BPF program names should be unique. Just like
with normal user-space linking process. So it's important to restrict this
aspect right now, keep static and non-entry functions as internal
implementation details, and not have to deal with regressions in behavior
later.
This patch leaves .BTF.ext adjustment as is until next patch.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200903203542.15944-5-andriin@fb.com
Fix up CO-RE relocation code to handle relocations against ELF sections
containing multiple BPF programs. This requires lookup of a BPF program by its
section name and instruction index it contains. While it could have been done
as a simple loop, it could run into performance issues pretty quickly, as
number of CO-RE relocations can be quite large in real-world applications, and
each CO-RE relocation incurs BPF program look up now. So instead of simple
loop, implement a binary search by section name + insn offset.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200903203542.15944-4-andriin@fb.com
Teach libbpf how to parse code sections into potentially multiple bpf_program
instances, based on ELF FUNC symbols. Each BPF program will keep track of its
position within containing ELF section for translating section instruction
offsets into program instruction offsets: regardless of BPF program's location
in ELF section, it's first instruction is always at local instruction offset
0, so when libbpf is working with relocations (which use section-based
instruction offsets) this is critical to make proper translations.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200903203542.15944-3-andriin@fb.com
libbpf ELF parsing logic might need symbols available before ELF parsing is
completed, so we need to make sure that symbols table section is found in
a separate pass before all the subsequent sections are processed.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200903203542.15944-2-andriin@fb.com
Fix use-after-free when a shared umem bind fails. The code incorrectly
tried to free the allocated buffer pool both in the bind code and then
later also when the socket was released. Fix this by setting the
buffer pool pointer to NULL after the bind code has freed the pool, so
that the socket release code will not try to free the pool. This is
the same solution as the regular, non-shared umem code path has. This
was missing from the shared umem path.
Fixes: b5aea28dca ("xsk: Add shared umem support between queue ids")
Reported-by: syzbot+5334f62e4d22804e646a@syzkaller.appspotmail.com
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/1599032164-25684-1-git-send-email-magnus.karlsson@intel.com
Currently, dma_map is being checked, when the right object identifier
to be null-checked is dma_map->dma_pages, instead.
Fix this by null-checking dma_map->dma_pages.
Fixes: 921b68692a ("xsk: Enable sharing of dma mappings")
Addresses-Coverity-ID: 1496811 ("Logically dead code")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Link: https://lore.kernel.org/bpf/20200902150750.GA7257@embeddedor
Neal Cardwell