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To support storing referenced PTR_TO_BTF_ID in maps, we require
associating a specific BTF ID with a 'destructor' kfunc. This is because
we need to release a live referenced pointer at a certain offset in map
value from the map destruction path, otherwise we end up leaking
resources.
Hence, introduce support for passing an array of btf_id, kfunc_btf_id
pairs that denote a BTF ID and its associated release function. Then,
add an accessor 'btf_find_dtor_kfunc' which can be used to look up the
destructor kfunc of a certain BTF ID. If found, we can use it to free
the object from the map free path.
The registration of these pairs also serve as a whitelist of structures
which are allowed as referenced PTR_TO_BTF_ID in a BPF map, because
without finding the destructor kfunc, we will bail and return an error.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220424214901.2743946-7-memxor@gmail.com
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Since now there might be at most 10 offsets that need handling in
copy_map_value, the manual shuffling and special case is no longer going
to work. Hence, let's generalise the copy_map_value function by using
a sorted array of offsets to skip regions that must be avoided while
copying into and out of a map value.
When the map is created, we populate the offset array in struct map,
Then, copy_map_value uses this sorted offset array is used to memcpy
while skipping timer, spin lock, and kptr. The array is allocated as
in most cases none of these special fields would be present in map
value, hence we can save on space for the common case by not embedding
the entire object inside bpf_map struct.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220424214901.2743946-6-memxor@gmail.com
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While we can guarantee that even for unreferenced kptr, the object
pointer points to being freed etc. can be handled by the verifier's
exception handling (normal load patching to PROBE_MEM loads), we still
cannot allow the user to pass these pointers to BPF helpers and kfunc,
because the same exception handling won't be done for accesses inside
the kernel. The same is true if a referenced pointer is loaded using
normal load instruction. Since the reference is not guaranteed to be
held while the pointer is used, it must be marked as untrusted.
Hence introduce a new type flag, PTR_UNTRUSTED, which is used to mark
all registers loading unreferenced and referenced kptr from BPF maps,
and ensure they can never escape the BPF program and into the kernel by
way of calling stable/unstable helpers.
In check_ptr_to_btf_access, the !type_may_be_null check to reject type
flags is still correct, as apart from PTR_MAYBE_NULL, only MEM_USER,
MEM_PERCPU, and PTR_UNTRUSTED may be set for PTR_TO_BTF_ID. The first
two are checked inside the function and rejected using a proper error
message, but we still want to allow dereference of untrusted case.
Also, we make sure to inherit PTR_UNTRUSTED when chain of pointers are
walked, so that this flag is never dropped once it has been set on a
PTR_TO_BTF_ID (i.e. trusted to untrusted transition can only be in one
direction).
In convert_ctx_accesses, extend the switch case to consider untrusted
PTR_TO_BTF_ID in addition to normal PTR_TO_BTF_ID for PROBE_MEM
conversion for BPF_LDX.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220424214901.2743946-5-memxor@gmail.com
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Extending the code in previous commits, introduce referenced kptr
support, which needs to be tagged using 'kptr_ref' tag instead. Unlike
unreferenced kptr, referenced kptr have a lot more restrictions. In
addition to the type matching, only a newly introduced bpf_kptr_xchg
helper is allowed to modify the map value at that offset. This transfers
the referenced pointer being stored into the map, releasing the
references state for the program, and returning the old value and
creating new reference state for the returned pointer.
Similar to unreferenced pointer case, return value for this case will
also be PTR_TO_BTF_ID_OR_NULL. The reference for the returned pointer
must either be eventually released by calling the corresponding release
function, otherwise it must be transferred into another map.
It is also allowed to call bpf_kptr_xchg with a NULL pointer, to clear
the value, and obtain the old value if any.
BPF_LDX, BPF_STX, and BPF_ST cannot access referenced kptr. A future
commit will permit using BPF_LDX for such pointers, but attempt at
making it safe, since the lifetime of object won't be guaranteed.
There are valid reasons to enforce the restriction of permitting only
bpf_kptr_xchg to operate on referenced kptr. The pointer value must be
consistent in face of concurrent modification, and any prior values
contained in the map must also be released before a new one is moved
into the map. To ensure proper transfer of this ownership, bpf_kptr_xchg
returns the old value, which the verifier would require the user to
either free or move into another map, and releases the reference held
for the pointer being moved in.
In the future, direct BPF_XCHG instruction may also be permitted to work
like bpf_kptr_xchg helper.
Note that process_kptr_func doesn't have to call
check_helper_mem_access, since we already disallow rdonly/wronly flags
for map, which is what check_map_access_type checks, and we already
ensure the PTR_TO_MAP_VALUE refers to kptr by obtaining its off_desc,
so check_map_access is also not required.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220424214901.2743946-4-memxor@gmail.com
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Add a new type flag for bpf_arg_type that when set tells verifier that
for a release function, that argument's register will be the one for
which meta.ref_obj_id will be set, and which will then be released
using release_reference. To capture the regno, introduce a new field
release_regno in bpf_call_arg_meta.
This would be required in the next patch, where we may either pass NULL
or a refcounted pointer as an argument to the release function
bpf_kptr_xchg. Just releasing only when meta.ref_obj_id is set is not
enough, as there is a case where the type of argument needed matches,
but the ref_obj_id is set to 0. Hence, we must enforce that whenever
meta.ref_obj_id is zero, the register that is to be released can only
be NULL for a release function.
Since we now indicate whether an argument is to be released in
bpf_func_proto itself, is_release_function helper has lost its utitlity,
hence refactor code to work without it, and just rely on
meta.release_regno to know when to release state for a ref_obj_id.
Still, the restriction of one release argument and only one ref_obj_id
passed to BPF helper or kfunc remains. This may be lifted in the future.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220424214901.2743946-3-memxor@gmail.com
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This commit introduces a new pointer type 'kptr' which can be embedded
in a map value to hold a PTR_TO_BTF_ID stored by a BPF program during
its invocation. When storing such a kptr, BPF program's PTR_TO_BTF_ID
register must have the same type as in the map value's BTF, and loading
a kptr marks the destination register as PTR_TO_BTF_ID with the correct
kernel BTF and BTF ID.
Such kptr are unreferenced, i.e. by the time another invocation of the
BPF program loads this pointer, the object which the pointer points to
may not longer exist. Since PTR_TO_BTF_ID loads (using BPF_LDX) are
patched to PROBE_MEM loads by the verifier, it would safe to allow user
to still access such invalid pointer, but passing such pointers into
BPF helpers and kfuncs should not be permitted. A future patch in this
series will close this gap.
The flexibility offered by allowing programs to dereference such invalid
pointers while being safe at runtime frees the verifier from doing
complex lifetime tracking. As long as the user may ensure that the
object remains valid, it can ensure data read by it from the kernel
object is valid.
The user indicates that a certain pointer must be treated as kptr
capable of accepting stores of PTR_TO_BTF_ID of a certain type, by using
a BTF type tag 'kptr' on the pointed to type of the pointer. Then, this
information is recorded in the object BTF which will be passed into the
kernel by way of map's BTF information. The name and kind from the map
value BTF is used to look up the in-kernel type, and the actual BTF and
BTF ID is recorded in the map struct in a new kptr_off_tab member. For
now, only storing pointers to structs is permitted.
An example of this specification is shown below:
#define __kptr __attribute__((btf_type_tag("kptr")))
struct map_value {
...
struct task_struct __kptr *task;
...
};
Then, in a BPF program, user may store PTR_TO_BTF_ID with the type
task_struct into the map, and then load it later.
Note that the destination register is marked PTR_TO_BTF_ID_OR_NULL, as
the verifier cannot know whether the value is NULL or not statically, it
must treat all potential loads at that map value offset as loading a
possibly NULL pointer.
Only BPF_LDX, BPF_STX, and BPF_ST (with insn->imm = 0 to denote NULL)
are allowed instructions that can access such a pointer. On BPF_LDX, the
destination register is updated to be a PTR_TO_BTF_ID, and on BPF_STX,
it is checked whether the source register type is a PTR_TO_BTF_ID with
same BTF type as specified in the map BTF. The access size must always
be BPF_DW.
For the map in map support, the kptr_off_tab for outer map is copied
from the inner map's kptr_off_tab. It was chosen to do a deep copy
instead of introducing a refcount to kptr_off_tab, because the copy only
needs to be done when paramterizing using inner_map_fd in the map in map
case, hence would be unnecessary for all other users.
It is not permitted to use MAP_FREEZE command and mmap for BPF map
having kptrs, similar to the bpf_timer case. A kptr also requires that
BPF program has both read and write access to the map (hence both
BPF_F_RDONLY_PROG and BPF_F_WRONLY_PROG are disallowed).
Note that check_map_access must be called from both
check_helper_mem_access and for the BPF instructions, hence the kptr
check must distinguish between ACCESS_DIRECT and ACCESS_HELPER, and
reject ACCESS_HELPER cases. We rename stack_access_src to bpf_access_src
and reuse it for this purpose.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220424214901.2743946-2-memxor@gmail.com
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Rename bpf_prog_run_array_cg_flags to bpf_prog_run_array_cg and
use it everywhere. check_return_code already enforces sane
return ranges for all cgroup types. (only egress and bind hooks have
uncanonical return ranges, the rest is using [0, 1])
No functional changes.
v2:
- 'func_ret & 1' under explicit test (Andrii & Martin)
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220425220448.3669032-1-sdf@google.com
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Allow attaching BTF-aware TRACING programs, previously attachable only
through BPF_RAW_TRACEPOINT_OPEN command, through LINK_CREATE command:
- BTF-aware raw tracepoints (tp_btf in libbpf lingo);
- fentry/fexit/fmod_ret programs;
- BPF LSM programs.
This change converges all bpf_link-based attachments under LINK_CREATE
command allowing to further extend the API with features like BPF cookie
under "multiplexed" link_create section of bpf_attr.
Non-BTF-aware raw tracepoints are left under BPF_RAW_TRACEPOINT_OPEN,
but there is nothing preventing opening them up to LINK_CREATE as well.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Kuifeng Lee <kuifeng@fb.com>
Link: https://lore.kernel.org/bpf/20220421033945.3602803-2-andrii@kernel.org
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Some functions in next patch want to use this function, and those
functions will be called by check_map_access, hence move it before
check_map_access.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Link: https://lore.kernel.org/bpf/20220415160354.1050687-3-memxor@gmail.com
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Next commit introduces field type 'kptr' whose kind will not be struct,
but pointer, and it will not be limited to one offset, but multiple
ones. Make existing btf_find_struct_field and btf_find_datasec_var
functions amenable to use for finding kptrs in map value, by moving
spin_lock and timer specific checks into their own function.
The alignment, and name are checked before the function is called, so it
is the last point where we can skip field or return an error before the
next loop iteration happens. Size of the field and type is meant to be
checked inside the function.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220415160354.1050687-2-memxor@gmail.com
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bpf_{sk,task,inode}_storage_free() do not need to use
call_rcu_tasks_trace as no BPF program should be accessing the owner
as it's being destroyed. The only other reader at this point is
bpf_local_storage_map_free() which uses normal RCU.
The only path that needs trace RCU are:
* bpf_local_storage_{delete,update} helpers
* map_{delete,update}_elem() syscalls
Fixes: 0fe4b381a59e ("bpf: Allow bpf_local_storage to be used by sleepable programs")
Signed-off-by: KP Singh <kpsingh@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20220418155158.2865678-1-kpsingh@kernel.org
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It is guaranteed that for modifiers, clang always places type tags
before other modifiers, and then the base type. We would like to rely on
this guarantee inside the kernel to make it simple to parse type tags
from BTF.
However, a user would be allowed to construct a BTF without such
guarantees. Hence, add a pass to check that in modifier chains, type
tags only occur at the head of the chain, and then don't occur later in
the chain.
If we see a type tag, we can have one or more type tags preceding other
modifiers that then never have another type tag. If we see other
modifiers, all modifiers following them should never be a type tag.
Instead of having to walk chains we verified previously, we can remember
the last good modifier type ID which headed a good chain. At that point,
we must have verified all other chains headed by type IDs less than it.
This makes the verification process less costly, and it becomes a simple
O(n) pass.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220419164608.1990559-2-memxor@gmail.com
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Commit 7d08c2c91171 ("bpf: Refactor BPF_PROG_RUN_ARRAY family of macros
into functions") switched a bunch of BPF_PROG_RUN macros to inline
routines. This changed the semantic a bit. Due to arguments expansion
of macros, it used to be:
rcu_read_lock();
array = rcu_dereference(cgrp->bpf.effective[atype]);
...
Now, with with inline routines, we have:
array_rcu = rcu_dereference(cgrp->bpf.effective[atype]);
/* array_rcu can be kfree'd here */
rcu_read_lock();
array = rcu_dereference(array_rcu);
I'm assuming in practice rcu subsystem isn't fast enough to trigger
this but let's use rcu API properly.
Also, rename to lower caps to not confuse with macros. Additionally,
drop and expand BPF_PROG_CGROUP_INET_EGRESS_RUN_ARRAY.
See [1] for more context.
[1] https://lore.kernel.org/bpf/CAKH8qBs60fOinFdxiiQikK_q0EcVxGvNTQoWvHLEUGbgcj1UYg@mail.gmail.com/T/#u
v2
- keep rcu locks inside by passing cgroup_bpf
Fixes: 7d08c2c91171 ("bpf: Refactor BPF_PROG_RUN_ARRAY family of macros into functions")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20220414161233.170780-1-sdf@google.com
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Remove/clean up unnecessary void * type castings.
Signed-off-by: Yu Zhe <yuzhe@nfschina.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220413015048.12319-1-yuzhe@nfschina.com
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Pull the migration of the BPF sysctl handling into BPF core. This work is
needed in both sysctl-next and bpf-next tree.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/bpf/b615bd44-6bd1-a958-7e3f-dd2ff58931a1@iogearbox.net
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We're moving sysctls out of kernel/sysctl.c as it is a mess. We
already moved all filesystem sysctls out. And with time the goal
is to move all sysctls out to their own subsystem/actual user.
kernel/sysctl.c has grown to an insane mess and its easy to run
into conflicts with it. The effort to move them out into various
subsystems is part of this.
Signed-off-by: Yan Zhu <zhuyan34@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/bpf/20220407070759.29506-1-zhuyan34@huawei.com
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The seq argument is assigned to meta.seq twice, the second one is
redundant, remove it.
This patch also removes a redundant space in bpf_iter_link_attach().
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220410060020.307283-1-ytcoode@gmail.com
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drivers/net/ethernet/microchip/lan966x/lan966x_main.c
d08ed852560e ("net: lan966x: Make sure to release ptp interrupt")
c8349639324a ("net: lan966x: Add FDMA functionality")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Daniel Borkmann says:
====================
pull-request: bpf-next 2022-04-09
We've added 63 non-merge commits during the last 9 day(s) which contain
a total of 68 files changed, 4852 insertions(+), 619 deletions(-).
The main changes are:
1) Add libbpf support for USDT (User Statically-Defined Tracing) probes.
USDTs are an abstraction built on top of uprobes, critical for tracing
and BPF, and widely used in production applications, from Andrii Nakryiko.
2) While Andrii was adding support for x86{-64}-specific logic of parsing
USDT argument specification, Ilya followed-up with USDT support for s390
architecture, from Ilya Leoshkevich.
3) Support name-based attaching for uprobe BPF programs in libbpf. The format
supported is `u[ret]probe/binary_path:[raw_offset|function[+offset]]`, e.g.
attaching to libc malloc can be done in BPF via SEC("uprobe/libc.so.6:malloc")
now, from Alan Maguire.
4) Various load/store optimizations for the arm64 JIT to shrink the image
size by using arm64 str/ldr immediate instructions. Also enable pointer
authentication to verify return address for JITed code, from Xu Kuohai.
5) BPF verifier fixes for write access checks to helper functions, e.g.
rd-only memory from bpf_*_cpu_ptr() must not be passed to helpers that
write into passed buffers, from Kumar Kartikeya Dwivedi.
6) Fix overly excessive stack map allocation for its base map structure and
buckets which slipped-in from cleanups during the rlimit accounting removal
back then, from Yuntao Wang.
7) Extend the unstable CT lookup helpers for XDP and tc/BPF to report netfilter
connection tracking tuple direction, from Lorenzo Bianconi.
8) Improve bpftool dump to show BPF program/link type names, Milan Landaverde.
9) Minor cleanups all over the place from various others.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (63 commits)
bpf: Fix excessive memory allocation in stack_map_alloc()
selftests/bpf: Fix return value checks in perf_event_stackmap test
selftests/bpf: Add CO-RE relos into linked_funcs selftests
libbpf: Use weak hidden modifier for USDT BPF-side API functions
libbpf: Don't error out on CO-RE relos for overriden weak subprogs
samples, bpf: Move routes monitor in xdp_router_ipv4 in a dedicated thread
libbpf: Allow WEAK and GLOBAL bindings during BTF fixup
libbpf: Use strlcpy() in path resolution fallback logic
libbpf: Add s390-specific USDT arg spec parsing logic
libbpf: Make BPF-side of USDT support work on big-endian machines
libbpf: Minor style improvements in USDT code
libbpf: Fix use #ifdef instead of #if to avoid compiler warning
libbpf: Potential NULL dereference in usdt_manager_attach_usdt()
selftests/bpf: Uprobe tests should verify param/return values
libbpf: Improve string parsing for uprobe auto-attach
libbpf: Improve library identification for uprobe binary path resolution
selftests/bpf: Test for writes to map key from BPF helpers
selftests/bpf: Test passing rdonly mem to global func
bpf: Reject writes for PTR_TO_MAP_KEY in check_helper_mem_access
bpf: Check PTR_TO_MEM | MEM_RDONLY in check_helper_mem_access
...
====================
Link: https://lore.kernel.org/r/20220408231741.19116-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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The 'n_buckets * (value_size + sizeof(struct stack_map_bucket))' part of the
allocated memory for 'smap' is never used after the memlock accounting was
removed, thus get rid of it.
[ Note, Daniel:
Commit b936ca643ade ("bpf: rework memlock-based memory accounting for maps")
moved `cost += n_buckets * (value_size + sizeof(struct stack_map_bucket))`
up and therefore before the bpf_map_area_alloc() allocation, sigh. In a later
step commit c85d69135a91 ("bpf: move memory size checks to bpf_map_charge_init()"),
and the overflow checks of `cost >= U32_MAX - PAGE_SIZE` moved into
bpf_map_charge_init(). And then 370868107bf6 ("bpf: Eliminate rlimit-based
memory accounting for stackmap maps") finally removed the bpf_map_charge_init().
Anyway, the original code did the allocation same way as /after/ this fix. ]
Fixes: b936ca643ade ("bpf: rework memlock-based memory accounting for maps")
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220407130423.798386-1-ytcoode@gmail.com
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It is not permitted to write to PTR_TO_MAP_KEY, but the current code in
check_helper_mem_access would allow for it, reject this case as well, as
helpers taking ARG_PTR_TO_UNINIT_MEM also take PTR_TO_MAP_KEY.
Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220319080827.73251-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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The commit being fixed was aiming to disallow users from incorrectly
obtaining writable pointer to memory that is only meant to be read. This
is enforced now using a MEM_RDONLY flag.
For instance, in case of global percpu variables, when the BTF type is
not struct (e.g. bpf_prog_active), the verifier marks register type as
PTR_TO_MEM | MEM_RDONLY from bpf_this_cpu_ptr or bpf_per_cpu_ptr
helpers. However, when passing such pointer to kfunc, global funcs, or
BPF helpers, in check_helper_mem_access, there is no expectation
MEM_RDONLY flag will be set, hence it is checked as pointer to writable
memory. Later, verifier sets up argument type of global func as
PTR_TO_MEM | PTR_MAYBE_NULL, so user can use a global func to get around
the limitations imposed by this flag.
This check will also cover global non-percpu variables that may be
introduced in kernel BTF in future.
Also, we update the log message for PTR_TO_BUF case to be similar to
PTR_TO_MEM case, so that the reason for error is clear to user.
Fixes: 34d3a78c681e ("bpf: Make per_cpu_ptr return rdonly PTR_TO_MEM.")
Reviewed-by: Hao Luo <haoluo@google.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220319080827.73251-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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When passing pointer to some map value to kfunc or global func, in
verifier we are passing meta as NULL to various functions, which uses
meta->raw_mode to check whether memory is being written to. Since some
kfunc or global funcs may also write to memory pointers they receive as
arguments, we must check for write access to memory. E.g. in some case
map may be read only and this will be missed by current checks.
However meta->raw_mode allows for uninitialized memory (e.g. on stack),
since there is not enough info available through BTF, we must perform
one call for read access (raw_mode = false), and one for write access
(raw_mode = true).
Fixes: e5069b9c23b3 ("bpf: Support pointers in global func args")
Fixes: d583691c47dc ("bpf: Introduce mem, size argument pair support for kfunc")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220319080827.73251-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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To move the list iterator variable into the list_for_each_entry_*()
macro in the future it should be avoided to use the list iterator
variable after the loop body.
To *never* use the list iterator variable after the loop it was
concluded to use a separate iterator variable instead of a
found boolean [1].
This removes the need to use the found variable (existed & supported)
and simply checking if the variable was set, can determine if the
break/goto was hit.
[1] https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220331091929.647057-1-jakobkoschel@gmail.com
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The attr->value_size is already assigned to smap->map.value_size
in bpf_map_init_from_attr(), there is no need to do it again in
stack_map_alloc().
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Link: https://lore.kernel.org/bpf/20220323073626.958652-1-ytcoode@gmail.com
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Clean the following coccicheck warning:
./kernel/trace/bpf_trace.c:2263:34-35: WARNING opportunity for swap().
./kernel/trace/bpf_trace.c:2264:40-41: WARNING opportunity for swap().
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220322062149.109180-1-jiapeng.chong@linux.alibaba.com
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Pull workqueue update from Tejun Heo:
"A lone commit fixing CPU offline handling for per-cpu wq workers so
that they don't bother isolated CPUs"
* 'for-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Restrict kworker in the offline CPU pool running on housekeeping CPUs
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When a CPU is going offline, all workers on the CPU's pool will have their
cpus_allowed cleared to cpu_possible_mask and can run on any CPUs including
the isolated ones. Instead, set cpus_allowed to wq_unbound_cpumask so that
the can avoid isolated CPUs.
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
"Nothing too interesting. This adds cpu controller selftests and there
are a couple code cleanup patches"
* 'for-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: remove the superfluous judgment
cgroup: Make cgroup_debug static
kseltest/cgroup: Make test_stress.sh work if run interactively
kselftest/cgroup: fix test_stress.sh to use OUTPUT dir
cgroup: Add config file to cgroup selftest suite
cgroup: Add test_cpucg_max_nested() testcase
cgroup: Add test_cpucg_max() testcase
cgroup: Add test_cpucg_nested_weight_underprovisioned() testcase
cgroup: Adding test_cpucg_nested_weight_overprovisioned() testcase
cgroup: Add test_cpucg_weight_underprovisioned() testcase
cgroup: Add test_cpucg_weight_overprovisioned() testcase
cgroup: Add test_cpucg_stats() testcase to cgroup cpu selftests
cgroup: Add new test_cpu.c test suite in cgroup selftests
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Remove the superfluous judgment since the function is
never called for a root cgroup, as suggested by Tejun.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Shida Zhang <zhangshida@kylinos.cn>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Make cgroup_debug static since it's only used in cgroup.c
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest
Pull KUnit updates from Shuah Khan:
"Several fixes, cleanups, and enhancements to tests and framework:
- introduce _NULL and _NOT_NULL macros to pointer error checks
- rework kunit_resource allocation policy to fix memory leaks when
caller doesn't specify free() function to be used when allocating
memory using kunit_add_resource() and kunit_alloc_resource() funcs.
- add ability to specify suite-level init and exit functions"
* tag 'linux-kselftest-kunit-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (41 commits)
kunit: tool: Use qemu-system-i386 for i386 runs
kunit: fix executor OOM error handling logic on non-UML
kunit: tool: update riscv QEMU config with new serial dependency
kcsan: test: use new suite_{init,exit} support
kunit: tool: Add list of all valid test configs on UML
kunit: take `kunit_assert` as `const`
kunit: tool: misc cleanups
kunit: tool: minor cosmetic cleanups in kunit_parser.py
kunit: tool: make parser stop overwriting status of suites w/ no_tests
kunit: tool: remove dead parse_crash_in_log() logic
kunit: tool: print clearer error message when there's no TAP output
kunit: tool: stop using a shell to run kernel under QEMU
kunit: tool: update test counts summary line format
kunit: bail out of test filtering logic quicker if OOM
lib/Kconfig.debug: change KUnit tests to default to KUNIT_ALL_TESTS
kunit: Rework kunit_resource allocation policy
kunit: fix debugfs code to use enum kunit_status, not bool
kfence: test: use new suite_{init/exit} support, add .kunitconfig
kunit: add ability to specify suite-level init and exit functions
kunit: rename print_subtest_{start,end} for clarity (s/subtest/suite)
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Use the newly added suite_{init,exit} support for suite-wide init and
cleanup. This avoids the unsupported method by which the test used to do
suite-wide init and cleanup (avoiding issues such as missing TAP
headers, and possible future conflicts).
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk updates from Petr Mladek:
- Offload writing printk() messages on consoles to per-console
kthreads.
It prevents soft-lockups when an extensive amount of messages is
printed. It was observed, for example, during boot of large systems
with a lot of peripherals like disks or network interfaces.
It prevents live-lockups that were observed, for example, when
messages about allocation failures were reported and a CPU handled
consoles instead of reclaiming the memory. It was hard to solve even
with rate limiting because it would need to take into account the
amount of messages and the speed of all consoles.
It is a must to have for real time. Otherwise, any printk() might
break latency guarantees.
The per-console kthreads allow to handle each console on its own
speed. Slow consoles do not longer slow down faster ones. And
printk() does not longer unpredictably slows down various code paths.
There are situations when the kthreads are either not available or
not reliable, for example, early boot, suspend, or panic. In these
situations, printk() uses the legacy mode and tries to handle
consoles immediately.
- Add documentation for the printk index.
* tag 'printk-for-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
printk, tracing: fix console tracepoint
printk: remove @console_locked
printk: extend console_lock for per-console locking
printk: add kthread console printers
printk: add functions to prefer direct printing
printk: add pr_flush()
printk: move buffer definitions into console_emit_next_record() caller
printk: refactor and rework printing logic
printk: add con_printk() macro for console details
printk: call boot_delay_msec() in printk_delay()
printk: get caller_id/timestamp after migration disable
printk: wake waiters for safe and NMI contexts
printk: wake up all waiters
printk: add missing memory barrier to wake_up_klogd()
printk: cpu sync always disable interrupts
printk: rename cpulock functions
printk/index: Printk index feature documentation
MAINTAINERS: Add printk indexing maintainers on mention of printk_index
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The original intent of the 'console' tracepoint per the commit 95100358491a
("printk/tracing: Add console output tracing") had been to "[...] record
any printk messages into the trace, regardless of the current console
loglevel. This can help correlate (existing) printk debugging with other
tracing."
Petr points out [1] that calling trace_console_rcuidle() in
call_console_driver() had been the wrong thing for a while, because
"printk() always used console_trylock() and the message was flushed to
the console only when the trylock succeeded. And it was always deferred
in NMI or when printed via printk_deferred()."
With the commit 09c5ba0aa2fc ("printk: add kthread console printers"),
things only got worse, and calls to call_console_driver() no longer
happen with typical printk() calls but always appear deferred [2].
As such, the tracepoint can no longer serve its purpose to clearly
correlate printk() calls and other tracing, as well as breaks usecases
that expect every printk() call to result in a callback of the console
tracepoint. Notably, the KFENCE and KCSAN test suites, which want to
capture console output and assume a printk() immediately gives us a
callback to the console tracepoint.
Fix the console tracepoint by moving it into printk_sprint() [3].
One notable difference is that by moving tracing into printk_sprint(),
the 'text' will no longer include the "header" (loglevel and timestamp),
but only the raw message. Arguably this is less of a problem now that
the console tracepoint happens on the printk() call and isn't delayed.
Link: https://lore.kernel.org/all/Ym+WqKStCg%2FEHfh3@alley/ [1]
Link: https://lore.kernel.org/all/CA+G9fYu2kS0wR4WqMRsj2rePKV9XLgOU1PiXnMvpT+Z=c2ucHA@mail.gmail.com/ [2]
Link: https://lore.kernel.org/all/87fslup9dx.fsf@jogness.linutronix.de/ [3]
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Signed-off-by: Marco Elver <elver@google.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: John Ogness <john.ogness@linutronix.de>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220503073844.4148944-1-elver@google.com
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The static global variable @console_locked is used to help debug
VT code to make sure that certain code paths are running with
the console_lock held. However, this information is also available
with the static global variable @console_kthreads_blocked (for
locking via console_lock()), and the static global variable
@console_kthreads_active (for locking via console_trylock()).
Remove @console_locked and update is_console_locked() to use the
alternative variables.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-16-john.ogness@linutronix.de
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Currently threaded console printers synchronize against each
other using console_lock(). However, different console drivers
are unrelated and do not require any synchronization between
each other. Removing the synchronization between the threaded
console printers will allow each console to print at its own
speed.
But the threaded consoles printers do still need to synchronize
against console_lock() callers. Introduce a per-console mutex
and a new console boolean field @blocked to provide this
synchronization.
console_lock() is modified so that it must acquire the mutex
of each console in order to set the @blocked field. Console
printing threads will acquire their mutex while printing a
record. If @blocked was set, the thread will go back to sleep
instead of printing.
The reason for the @blocked boolean field is so that
console_lock() callers do not need to acquire multiple console
mutexes simultaneously, which would introduce unnecessary
complexity due to nested mutex locking. Also, a new field
was chosen instead of adding a new @flags value so that the
blocked status could be checked without concern of reading
inconsistent values due to @flags updates from other contexts.
Threaded console printers also need to synchronize against
console_trylock() callers. Since console_trylock() may be
called from any context, the per-console mutex cannot be used
for this synchronization. (mutex_trylock() cannot be called
from atomic contexts.) Introduce a global atomic counter to
identify if any threaded printers are active. The threaded
printers will also check the atomic counter to identify if the
console has been locked by another task via console_trylock().
Note that @console_sem is still used to provide synchronization
between console_lock() and console_trylock() callers.
A locking overview for console_lock(), console_trylock(), and the
threaded printers is as follows (pseudo code):
console_lock()
{
down(&console_sem);
for_each_console(con) {
mutex_lock(&con->lock);
con->blocked = true;
mutex_unlock(&con->lock);
}
/* console_lock acquired */
}
console_trylock()
{
if (down_trylock(&console_sem) == 0) {
if (atomic_cmpxchg(&console_kthreads_active, 0, -1) == 0) {
/* console_lock acquired */
}
}
}
threaded_printer()
{
mutex_lock(&con->lock);
if (!con->blocked) {
/* console_lock() callers blocked */
if (atomic_inc_unless_negative(&console_kthreads_active)) {
/* console_trylock() callers blocked */
con->write();
atomic_dec(&console_lock_count);
}
}
mutex_unlock(&con->lock);
}
The console owner and waiter logic now only applies between contexts
that have taken the console_lock via console_trylock(). Threaded
printers never take the console_lock, so they do not have a
console_lock to handover. Tasks that have used console_lock() will
block the threaded printers using a mutex and if the console_lock
is handed over to an atomic context, it would be unable to unblock
the threaded printers. However, the console_trylock() case is
really the only scenario that is interesting for handovers anyway.
@panic_console_dropped must change to atomic_t since it is no longer
protected exclusively by the console_lock.
Since threaded printers remain asleep if they see that the console
is locked, they now must be explicitly woken in __console_unlock().
This means wake_up_klogd() calls following a console_unlock() are
no longer necessary and are removed.
Also note that threaded printers no longer need to check
@console_suspended. The check for the @blocked field implicitly
covers the suspended console case.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/878rrs6ft7.fsf@jogness.linutronix.de
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Create a kthread for each console to perform console printing. During
normal operation (@system_state == SYSTEM_RUNNING), the kthread
printers are responsible for all printing on their respective
consoles.
During non-normal operation, console printing is done as it has been:
within the context of the printk caller or within irqwork triggered
by the printk caller, referred to as direct printing.
Since threaded console printers are responsible for all printing
during normal operation, this also includes messages generated via
deferred printk calls. If direct printing is in effect during a
deferred printk call, the queued irqwork will perform the direct
printing. To make it clear that this is the only time that the
irqwork will perform direct printing, rename the flag
PRINTK_PENDING_OUTPUT to PRINTK_PENDING_DIRECT_OUTPUT.
Threaded console printers synchronize against each other and against
console lockers by taking the console lock for each message that is
printed.
Note that the kthread printers do not care about direct printing.
They will always try to print if new records are available. They can
be blocked by direct printing, but will be woken again once direct
printing is finished.
Console unregistration is a bit tricky because the associated
kthread printer cannot be stopped while the console lock is held.
A policy is implemented that states: whichever task clears
con->thread (under the console lock) is responsible for stopping
the kthread. unregister_console() will clear con->thread while
the console lock is held and then stop the kthread after releasing
the console lock.
For consoles that have implemented the exit() callback, the kthread
is stopped before exit() is called.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-14-john.ogness@linutronix.de
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Once kthread printing is available, console printing will no longer
occur in the context of the printk caller. However, there are some
special contexts where it is desirable for the printk caller to
directly print out kernel messages. Using pr_flush() to wait for
threaded printers is only possible if the caller is in a sleepable
context and the kthreads are active. That is not always the case.
Introduce printk_prefer_direct_enter() and printk_prefer_direct_exit()
functions to explicitly (and globally) activate/deactivate preferred
direct console printing. The term "direct console printing" refers to
printing to all enabled consoles from the context of the printk
caller. The term "prefer" is used because this type of printing is
only best effort. If the console is currently locked or other
printers are already actively printing, the printk caller will need
to rely on the other contexts to handle the printing.
This preferred direct printing is how all printing has been handled
until now (unless it was explicitly deferred).
When kthread printing is introduced, there may be some unanticipated
problems due to kthreads being unable to flush important messages.
In order to minimize such risks, preferred direct printing is
activated for the primary important messages when the system
experiences general types of major errors. These are:
- emergency reboot/shutdown
- cpu and rcu stalls
- hard and soft lockups
- hung tasks
- warn
- sysrq
Note that since kthread printing does not yet exist, no behavior
changes result from this commit. This is only implementing the
counter and marking the various places where preferred direct
printing is active.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org> # for RCU
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-13-john.ogness@linutronix.de
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Provide a might-sleep function to allow waiting for console printers
to catch up to the latest logged message.
Use pr_flush() whenever it is desirable to get buffered messages
printed before continuing: suspend_console(), resume_console(),
console_stop(), console_start(), console_unblank().
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-12-john.ogness@linutronix.de
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Extended consoles print extended messages and do not print messages about
dropped records.
Non-extended consoles print "normal" messages as well as extra messages
about dropped records.
Currently the buffers for these various message types are defined within
the functions that might use them and their usage is based upon the
CON_EXTENDED flag. This will be a problem when moving to kthread printers
because each printer must be able to provide its own buffers.
Move all the message buffer definitions outside of
console_emit_next_record(). The caller knows if extended or dropped
messages should be printed and can specify the appropriate buffers to
use. The console_emit_next_record() and call_console_driver() functions
can know what to print based on whether specified buffers are non-NULL.
With this change, buffer definition/allocation/specification is separated
from the code that does the various types of string printing.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-11-john.ogness@linutronix.de
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Refactor/rework printing logic in order to prepare for moving to
threaded console printing.
- Move @console_seq into struct console so that the current
"position" of each console can be tracked individually.
- Move @console_dropped into struct console so that the current drop
count of each console can be tracked individually.
- Modify printing logic so that each console independently loads,
prepares, and prints its next record.
- Remove exclusive_console logic. Since console positions are
handled independently, replaying past records occurs naturally.
- Update the comments explaining why preemption is disabled while
printing from printk() context.
With these changes, there is a change in behavior: the console
replaying the log (formerly exclusive console) will no longer block
other consoles. New messages appear on the other consoles while the
newly added console is still replaying.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-10-john.ogness@linutronix.de
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It is useful to generate log messages that include details about
the related console. Rather than duplicate the code to assemble
the details, put that code into a macro con_printk().
Once console printers become threaded, this macro will find more
users.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-9-john.ogness@linutronix.de
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boot_delay_msec() is always called immediately before printk_delay()
so just call it from within printk_delay().
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-8-john.ogness@linutronix.de
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Currently the local CPU timestamp and caller_id for the record are
collected while migration is enabled. Since this information is
CPU-specific, it should be collected with migration disabled.
Migration is disabled immediately after collecting this information
anyway, so just move the information collection to after the
migration disabling.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-7-john.ogness@linutronix.de
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When printk() is called from safe or NMI contexts, it will directly
store the record (vprintk_store()) and then defer the console output.
However, defer_console_output() only causes console printing and does
not wake any waiters of new records.
Wake waiters from defer_console_output() so that they also are aware
of the new records from safe and NMI contexts.
Fixes: 03fc7f9c99c1 ("printk/nmi: Prevent deadlock when accessing the main log buffer in NMI")
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-6-john.ogness@linutronix.de
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There can be multiple tasks waiting for new records. They should
all be woken. Use wake_up_interruptible_all() instead of
wake_up_interruptible().
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-5-john.ogness@linutronix.de
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It is important that any new records are visible to preparing
waiters before the waker checks if the wait queue is empty.
Otherwise it is possible that:
- there are new records available
- the waker sees an empty wait queue and does not wake
- the preparing waiter sees no new records and begins to wait
This is exactly the problem that the function description of
waitqueue_active() warns about.
Use wq_has_sleeper() instead of waitqueue_active() because it
includes the necessary full memory barrier.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-4-john.ogness@linutronix.de
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Since the printk cpulock is CPU-reentrant and since it is used
in all contexts, its usage must be carefully considered and
most likely will require programming locklessly. To avoid
mistaking the printk cpulock as a typical lock, rename it to
cpu_sync. The main functions then become:
printk_cpu_sync_get_irqsave(flags);
printk_cpu_sync_put_irqrestore(flags);
Add extra notes of caution in the function description to help
developers understand the requirements for correct usage.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-2-john.ogness@linutronix.de
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