GCC and LLVM define a no_caller_saved_registers function attribute.
This attribute means that function scratches only some of
the caller saved registers defined by ABI.
For BPF the set of such registers could be defined as follows:
- R0 is scratched only if function is non-void;
- R1-R5 are scratched only if corresponding parameter type is defined
in the function prototype.
This commit introduces flag bpf_func_prot->allow_nocsr.
If this flag is set for some helper function, verifier assumes that
it follows no_caller_saved_registers calling convention.
The contract between kernel and clang allows to simultaneously use
such functions and maintain backwards compatibility with old
kernels that don't understand no_caller_saved_registers calls
(nocsr for short):
- clang generates a simple pattern for nocsr calls, e.g.:
r1 = 1;
r2 = 2;
*(u64 *)(r10 - 8) = r1;
*(u64 *)(r10 - 16) = r2;
call %[to_be_inlined]
r2 = *(u64 *)(r10 - 16);
r1 = *(u64 *)(r10 - 8);
r0 = r1;
r0 += r2;
exit;
- kernel removes unnecessary spills and fills, if called function is
inlined by verifier or current JIT (with assumption that patch
inserted by verifier or JIT honors nocsr contract, e.g. does not
scratch r3-r5 for the example above), e.g. the code above would be
transformed to:
r1 = 1;
r2 = 2;
call %[to_be_inlined]
r0 = r1;
r0 += r2;
exit;
Technically, the transformation is split into the following phases:
- function mark_nocsr_patterns(), called from bpf_check()
searches and marks potential patterns in instruction auxiliary data;
- upon stack read or write access,
function check_nocsr_stack_contract() is used to verify if
stack offsets, presumably reserved for nocsr patterns, are used
only from those patterns;
- function remove_nocsr_spills_fills(), called from bpf_check(),
applies the rewrite for valid patterns.
See comment in mark_nocsr_pattern_for_call() for more details.
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240722233844.1406874-3-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
syzbot reported a kernel crash due to
commit 1f1e864b65 ("bpf: Handle sign-extenstin ctx member accesses").
The reason is due to sign-extension of 32-bit load for
packet data/data_end/data_meta uapi field.
The original code looks like:
r2 = *(s32 *)(r1 + 76) /* load __sk_buff->data */
r3 = *(u32 *)(r1 + 80) /* load __sk_buff->data_end */
r0 = r2
r0 += 8
if r3 > r0 goto +1
...
Note that __sk_buff->data load has 32-bit sign extension.
After verification and convert_ctx_accesses(), the final asm code looks like:
r2 = *(u64 *)(r1 +208)
r2 = (s32)r2
r3 = *(u64 *)(r1 +80)
r0 = r2
r0 += 8
if r3 > r0 goto pc+1
...
Note that 'r2 = (s32)r2' may make the kernel __sk_buff->data address invalid
which may cause runtime failure.
Currently, in C code, typically we have
void *data = (void *)(long)skb->data;
void *data_end = (void *)(long)skb->data_end;
...
and it will generate
r2 = *(u64 *)(r1 +208)
r3 = *(u64 *)(r1 +80)
r0 = r2
r0 += 8
if r3 > r0 goto pc+1
If we allow sign-extension,
void *data = (void *)(long)(int)skb->data;
void *data_end = (void *)(long)skb->data_end;
...
the generated code looks like
r2 = *(u64 *)(r1 +208)
r2 <<= 32
r2 s>>= 32
r3 = *(u64 *)(r1 +80)
r0 = r2
r0 += 8
if r3 > r0 goto pc+1
and this will cause verification failure since "r2 <<= 32" is not allowed
as "r2" is a packet pointer.
To fix this issue for case
r2 = *(s32 *)(r1 + 76) /* load __sk_buff->data */
this patch added additional checking in is_valid_access() callback
function for packet data/data_end/data_meta access. If those accesses
are with sign-extenstion, the verification will fail.
[1] https://lore.kernel.org/bpf/000000000000c90eee061d236d37@google.com/
Reported-by: syzbot+ad9ec60c8eaf69e6f99c@syzkaller.appspotmail.com
Fixes: 1f1e864b65 ("bpf: Handle sign-extenstin ctx member accesses")
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240723153439.2429035-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Extract the part of check_helper_call() as a utility function allowing
to query 'struct bpf_func_proto' for a specific helper function id.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240722233844.1406874-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Actually use previously defined LDFLAGS during build and add support for
LDLIBS to link extra standalone libraries e.g. 'argp' which is not provided
by musl libc.
Fixes: 585bf4640e ("tools: runqslower: Add EXTRA_CFLAGS and EXTRA_LDFLAGS support")
Signed-off-by: Tony Ambardar <tony.ambardar@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/bpf/20240723003045.2273499-1-tony.ambardar@gmail.com
Make log output incorrectly shows 'test_maps' as the binary name for every
'CLNG-BPF' build step, apparently picking up the last value defined for the
$(TRUNNER_BINARY) variable. Update the 'CLANG_BPF_BUILD_RULE' variants to
fix this confusing output.
Current output:
CLNG-BPF [test_maps] access_map_in_map.bpf.o
GEN-SKEL [test_progs] access_map_in_map.skel.h
...
CLNG-BPF [test_maps] access_map_in_map.bpf.o
GEN-SKEL [test_progs-no_alu32] access_map_in_map.skel.h
...
CLNG-BPF [test_maps] access_map_in_map.bpf.o
GEN-SKEL [test_progs-cpuv4] access_map_in_map.skel.h
After fix:
CLNG-BPF [test_progs] access_map_in_map.bpf.o
GEN-SKEL [test_progs] access_map_in_map.skel.h
...
CLNG-BPF [test_progs-no_alu32] access_map_in_map.bpf.o
GEN-SKEL [test_progs-no_alu32] access_map_in_map.skel.h
...
CLNG-BPF [test_progs-cpuv4] access_map_in_map.bpf.o
GEN-SKEL [test_progs-cpuv4] access_map_in_map.skel.h
Fixes: a5d0c26a27 ("selftests/bpf: Add a cpuv4 test runner for cpu=v4 testing")
Fixes: 89ad7420b2 ("selftests/bpf: Drop the need for LLVM's llc")
Signed-off-by: Tony Ambardar <tony.ambardar@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20240720052535.2185967-1-tony.ambardar@gmail.com
Without CONFIG_NET_FOU bpf selftests are unable to build because of
missing definitions. Add ___local versions of struct bpf_fou_encap and
enum bpf_fou_encap_type to fix the issue.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240723071031.3389423-1-asavkov@redhat.com
Adding test that attaches/detaches multiple consumers on
single uprobe and verifies all were hit as expected.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240722202758.3889061-3-jolsa@kernel.org
Linking uprobe_multi.c on mips64el fails due to relocation overflows, when
the GOT entries required exceeds the default maximum. Add a specific CFLAGS
(-mxgot) for uprobe_multi.c on MIPS that allows using a larger GOT and
avoids errors such as:
/tmp/ccBTNQzv.o: in function `bench':
uprobe_multi.c:49:(.text+0x1d7720): relocation truncated to fit: R_MIPS_GOT_DISP against `uprobe_multi_func_08188'
uprobe_multi.c:49:(.text+0x1d7730): relocation truncated to fit: R_MIPS_GOT_DISP against `uprobe_multi_func_08189'
...
collect2: error: ld returned 1 exit status
Fixes: 519dfeaf51 ("selftests/bpf: Add uprobe_multi test program")
Signed-off-by: Tony Ambardar <tony.ambardar@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/14eb7b70f8ccef9834874d75eb373cb9292129da.1721692479.git.tony.ambardar@gmail.com
Update get_sys_includes in Makefile with missing MIPS-related definitions
to fix many, many compilation errors building selftests/bpf. The following
added defines drive conditional logic in system headers for word-size and
endianness selection:
MIPSEL, MIPSEB
_MIPS_SZPTR
_MIPS_SZLONG
_MIPS_SIM, _ABIO32, _ABIN32, _ABI64
Signed-off-by: Tony Ambardar <tony.ambardar@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/f3cfceaf5299cdd2ac0e0a36072d6ca7be23e603.1721692479.git.tony.ambardar@gmail.com
Regular BPF hash map is not mmap-able from user space. However, map-in-map
with outer map of type BPF_MAP_TYPE_HASH_OF_MAPS and mmap-able array as
inner map can perform similar operations as a mmap-able hash map. This
can be used by applications that benefit from fast accesses to some local
data.
Add a selftest to show this use case.
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240723051455.1589192-1-song@kernel.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Geliang Tang says:
====================
This set is part 10 of series "use network helpers" all BPF selftests
wide.
Patches 1-3 drop local functions make_client(), make_socket() and
inetaddr_len() in sk_lookup.c. Patch 4 drops a useless function
__start_server() in network_helpers.c.
====================
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
The helper start_server_addr() is a wrapper of __start_server(), the
only difference between them is __start_server() accepts a sockaddr type
address parameter, but start_server_addr() accepts a sockaddr_storage one.
This patch drops __start_server(), and updates the callers to invoke
start_server_addr() instead.
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Link: https://lore.kernel.org/r/31399df7cb957b7c233e79963b0aa0dc4278d273.1721475357.git.tanggeliang@kylinos.cn
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
No need to use a dedicated helper inetaddr_len() to get the length of
the IPv4 or IPv6 address, it can be got by make_sockaddr(), this patch
drops it.
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Link: https://lore.kernel.org/r/32e2a4122921051da38a6e4fbb2ebee5f0af5a4e.1721475357.git.tanggeliang@kylinos.cn
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
This patch uses the public network helers client_socket() + make_sockaddr()
in sk_lookup.c to create the client socket, set the timeout sockopts, and
make the connecting address. The local defined function make_socket()
can be dropped then.
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Link: https://lore.kernel.org/r/588771977ac48c27f73526d8421a84b91d7cf218.1721475357.git.tanggeliang@kylinos.cn
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
This patch uses the new helper connect_to_addr_str() in sk_lookup.c to
create the client socket and connect to the server, instead of using local
defined function make_client(). This local function can be dropped then.
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Link: https://lore.kernel.org/r/058199d7ab46802249dae066ca22c98f6be508ee.1721475357.git.tanggeliang@kylinos.cn
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
test_progs-no_alu32 -t libbpf_get_fd_by_id_opts
is being rejected by the verifier with the following error
due to compiler optimization:
6: (67) r0 <<= 62 ; R0_w=scalar(smax=0x4000000000000000,umax=0xc000000000000000,smin32=0,smax32=umax32=0,var_off=(0x0; 0xc000000000000000))
7: (c7) r0 s>>= 63 ; R0_w=scalar(smin=smin32=-1,smax=smax32=0)
; @ test_libbpf_get_fd_by_id_opts.c:0
8: (57) r0 &= -13 ; R0_w=scalar(smax=0x7ffffffffffffff3,umax=0xfffffffffffffff3,smax32=0x7ffffff3,umax32=0xfffffff3,var_off=(0x0; 0xfffffffffffffff3))
; int BPF_PROG(check_access, struct bpf_map *map, fmode_t fmode) @ test_libbpf_get_fd_by_id_opts.c:27
9: (95) exit
At program exit the register R0 has smax=9223372036854775795 should have been in [-4095, 0]
Workaround by adding barrier().
Eventually the verifier will be able to recognize it.
Fixes: 5d99e198be ("bpf, lsm: Add check for BPF LSM return value")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
The serial console settings in the chosen node are device-specific,
not SoC-specific. Move the chosen node out of bcm21664.dtsi and into
the only DTS that uses it, bcm21664-garnet.dts.
Signed-off-by: Artur Weber <aweber.kernel@gmail.com>
Link: https://lore.kernel.org/r/20240729-bcm21664-common-v2-1-ebc21a89bf63@gmail.com
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Document alreasdy used binding for Syscon / AVS monitor:
brcm,bcm2711-avs-monitor to fix dt_binding_check and dtbs_check warnings
like:
brcm,avs-ro-thermal.example.dtb: /example-0/avs-monitor@7d5d2000: failed to match any schema with compatible: ['brcm,bcm2711-avs-monitor', 'syscon', 'simple-mfd']
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20240517125138.53441-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
The BCM2712 SoC family can be found on Raspberry Pi 5.
Add minimal SoC and board (Rpi5 specific) dts file to be able to
boot from SD card and use console on debug UART.
Signed-off-by: Andrea della Porta <andrea.porta@suse.com>
Reviewed-by: Stefan Wahren <wahrenst@gmx.net>
Link: https://lore.kernel.org/r/874589f6c621036620cca944986e5be7238b4784.1717061147.git.andrea.porta@suse.com
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
This patch 1) fixes all the issues (not most) reported by pylint,
2) add the functionability to tackle documents that need translation,
3) add logging to adjust the logging level and log file
Signed-off-by: Dongliang Mu <dzm91@hust.edu.cn>
Reviewed-by: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240719041400.3909775-2-dzm91@hust.edu.cn
The goal of the workflows@ mailing list was to make it easier for
maintainers who don't use lore+lei to subscribe to topics related
to process changes. In other words it should cover changes to Documentation
files which most maintainers should know about. Recent changes from Kees [1]
to provide guidelines on naming KUnit files did not fall under workflows@
since Documentation/dev-tools/ isn't covered. The patch volume for
dev-tools isn't huge and most of the changes are interesting. Add it.
Link: https://lore.kernel.org/20240720165441.it.320-kees@kernel.org/ # [1]
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240723223258.2197852-1-kuba@kernel.org
Finish the translation of kbuild/headers_install.rst and
kbuild/index.rst, then add kbuild into zh_CN/index.rst.
Update to commit 5b67fbfc32 ("Merge tag 'kbuild-v5.7' of
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild")
Signed-off-by: Dongliang Mu <dzm91@hust.edu.cn>
Reviewed-by: Alex Shi <alexs@kernel.org>
Reviewed-by: Yanteng Si <siyanteng@loongson.cn>
[jc: added missing EOF newline ]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240726145754.2598197-1-dzm91@hust.edu.cn
Since v6.8 the definition of GFP_NOWAIT has implied __GFP_NOWARN,
so it is now redundant to add this flag explicitly.
Update the docs to match, and emphasise the need for a fallback
when using GFP_NOWAIT.
Fixes: 16f5dfbc85 ("gfp: include __GFP_NOWARN in GFP_NOWAIT")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240729140127.244606-1-Dave.Martin@arm.com
Move management of the perf_event->security blob out of the individual
security modules and into the security infrastructure. Instead of
allocating the blobs from within the modules the modules tell the
infrastructure how much space is required, and the space is allocated
there. There are no longer any modules that require the perf_event_free()
hook. The hook definition has been removed.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: John Johansen <john.johansen@canonical.com>
[PM: subject tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Move management of the infiniband security blob out of the individual
security modules and into the LSM infrastructure. The security modules
tell the infrastructure how much space they require at initialization.
There are no longer any modules that require the ib_free() hook.
The hook definition has been removed.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: John Johansen <john.johansen@canonical.com>
[PM: subject tweak, selinux style fixes]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Move management of the dev_tun security blob out of the individual
security modules and into the LSM infrastructure. The security modules
tell the infrastructure how much space they require at initialization.
There are no longer any modules that require the dev_tun_free hook.
The hook definition has been removed.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: John Johansen <john.johansen@canonical.com>
[PM: subject tweak, selinux style fixes]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Create a helper function lsm_blob_alloc() for general use in the hook
specific functions that allocate LSM blobs. Change the hook specific
functions to use this helper. This reduces the code size by a small
amount and will make adding new instances of infrastructure managed
security blobs easier.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: John Johansen <john.johansen@canonical.com>
[PM: subject tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Move management of the key->security blob out of the individual security
modules and into the security infrastructure. Instead of allocating the
blobs from within the modules the modules tell the infrastructure how
much space is required, and the space is allocated there. There are
no existing modules that require a key_free hook, so the call to it and
the definition for it have been removed.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: John Johansen <john.johansen@canonical.com>
[PM: subject tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Move management of the sock->sk_security blob out
of the individual security modules and into the security
infrastructure. Instead of allocating the blobs from within
the modules the modules tell the infrastructure how much
space is required, and the space is allocated there.
Acked-by: Paul Moore <paul@paul-moore.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: subject tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Jakub reports build failures when merging linux/master with net tree:
CXX test_cpp
In file included from <built-in>:454:
<command line>:2:9: error: '_GNU_SOURCE' macro redefined [-Werror,-Wmacro-redefined]
2 | #define _GNU_SOURCE
| ^
<built-in>:445:9: note: previous definition is here
445 | #define _GNU_SOURCE 1
The culprit is commit cc937dad85 ("selftests: centralize -D_GNU_SOURCE= to
CFLAGS in lib.mk") which unconditionally added -D_GNU_SOUCE to CLFAGS.
Apparently clang++ also unconditionally adds it for the C++ targets [0]
which causes a conflict. Add small change in the selftests makefile
to filter it out for test_cpp.
Not sure which tree it should go via, targeting bpf for now, but net
might be better?
0: https://stackoverflow.com/questions/11670581/why-is-gnu-source-defined-by-default-and-how-to-turn-it-off
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20240725214029.1760809-1-sdf@fomichev.me
Refactor the code in selinux_netlbl_sock_genattr to return ERR_PTR
when an error occurs.
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Simplifies the logic for determining the security context type in
security_compute_sid, enhancing readability and efficiency.
Consolidates default type assignment logic next to type transition
checks, removing redundancy and improving code flow.
Signed-off-by: Canfeng Guo <guocanfeng@uniontech.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Add test for lsm tail call to ensure tail call can only be used between
bpf lsm progs attached to the same hook.
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20240719110059.797546-9-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
The return ranges of some bpf lsm test progs can not be deduced by
the verifier accurately. To avoid erroneous rejections, add explicit
return value checks for these progs.
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20240719110059.797546-8-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
After checking lsm hook return range in verifier, the test case
"test_progs -t test_lsm" failed, and the failure log says:
libbpf: prog 'test_int_hook': BPF program load failed: Invalid argument
libbpf: prog 'test_int_hook': -- BEGIN PROG LOAD LOG --
0: R1=ctx() R10=fp0
; int BPF_PROG(test_int_hook, struct vm_area_struct *vma, @ lsm.c:89
0: (79) r0 = *(u64 *)(r1 +24) ; R0_w=scalar(smin=smin32=-4095,smax=smax32=0) R1=ctx()
[...]
24: (b4) w0 = -1 ; R0_w=0xffffffff
; int BPF_PROG(test_int_hook, struct vm_area_struct *vma, @ lsm.c:89
25: (95) exit
At program exit the register R0 has smin=4294967295 smax=4294967295 should have been in [-4095, 0]
It can be seen that instruction "w0 = -1" zero extended -1 to 64-bit
register r0, setting both smin and smax values of r0 to 4294967295.
This resulted in a false reject when r0 was checked with range [-4095, 0].
Given bpf lsm does not return 64-bit values, this patch fixes it by changing
the compare between r0 and return range from 64-bit operation to 32-bit
operation for bpf lsm.
Fixes: 8fa4ecd49b ("bpf: enforce exact retval range on subprog/callback exit")
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20240719110059.797546-5-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
bpf progs can be attached to kernel functions, and the attached functions
can take different parameters or return different return values. If
prog attached to one kernel function tail calls prog attached to another
kernel function, the ctx access or return value verification could be
bypassed.
For example, if prog1 is attached to func1 which takes only 1 parameter
and prog2 is attached to func2 which takes two parameters. Since verifier
assumes the bpf ctx passed to prog2 is constructed based on func2's
prototype, verifier allows prog2 to access the second parameter from
the bpf ctx passed to it. The problem is that verifier does not prevent
prog1 from passing its bpf ctx to prog2 via tail call. In this case,
the bpf ctx passed to prog2 is constructed from func1 instead of func2,
that is, the assumption for ctx access verification is bypassed.
Another example, if BPF LSM prog1 is attached to hook file_alloc_security,
and BPF LSM prog2 is attached to hook bpf_lsm_audit_rule_known. Verifier
knows the return value rules for these two hooks, e.g. it is legal for
bpf_lsm_audit_rule_known to return positive number 1, and it is illegal
for file_alloc_security to return positive number. So verifier allows
prog2 to return positive number 1, but does not allow prog1 to return
positive number. The problem is that verifier does not prevent prog1
from calling prog2 via tail call. In this case, prog2's return value 1
will be used as the return value for prog1's hook file_alloc_security.
That is, the return value rule is bypassed.
This patch adds restriction for tail call to prevent such bypasses.
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20240719110059.797546-4-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
A bpf prog returning a positive number attached to file_alloc_security
hook makes kernel panic.
This happens because file system can not filter out the positive number
returned by the LSM prog using IS_ERR, and misinterprets this positive
number as a file pointer.
Given that hook file_alloc_security never returned positive number
before the introduction of BPF LSM, and other BPF LSM hooks may
encounter similar issues, this patch adds LSM return value check
in verifier, to ensure no unexpected value is returned.
Fixes: 520b7aa00d ("bpf: lsm: Initialize the BPF LSM hooks")
Reported-by: Xin Liu <liuxin350@huawei.com>
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240719110059.797546-3-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Add a disabled hooks list for BPF LSM. progs being attached to the
listed hooks will be rejected by the verifier.
Suggested-by: KP Singh <kpsingh@kernel.org>
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20240719110059.797546-2-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Martin KaFai Lau says:
====================
bpf: Retire the unsupported_ops usage in struct_ops
From: Martin KaFai Lau <martin.lau@kernel.org>
This series retires the unsupported_ops usage and depends on the
null-ness check on the cfi_stubs instead.
Please see individual patches for details.
v2:
- Fixed a gcc compiler warning on Patch 1.
====================
Link: https://lore.kernel.org/r/20240722183049.2254692-1-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
There is an existing "bpf_tcp_ca/unsupp_cong_op" test to ensure
the unsupported tcp-cc "get_info" struct_ops prog cannot be loaded.
This patch adds a new test in the bpf_testmod such that the
unsupported ops test does not depend on other kernel subsystem
where its supporting ops may be changed in the future.
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240722183049.2254692-4-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
The tramp_1 to tramp_40 ops is not set in the cfi_stubs in the
bpf_testmod_ops. It fails the struct_ops_multi_pages test after
retiring the unsupported_ops in the earlier patch.
This patch initializes them in a loop during the bpf_testmod_init().
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240722183049.2254692-3-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
