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btf_add_type() stores the types of a BTF in btf->types[], which can hold at
most BTF_MAX_TYPE entries. The types of a split BTF get IDs start_id ..
start_id + nr_types - 1, so only BTF_MAX_TYPE - start_id of them fit, but
neither the limit check nor the size used to grow the array accounts for
start_id: the check is an equality test against BTF_MAX_TYPE
('start_id + btf->types_size == BTF_MAX_TYPE') and the new size is clamped
to BTF_MAX_TYPE.
The check therefore only fires if the array happens to grow to exactly
BTF_MAX_TYPE - start_id entries. Otherwise, if the module has more than
BTF_MAX_TYPE types, the array is filled up to BTF_MAX_TYPE entries. The
next type that needs to be added reallocates the array to the same size,
after which btf->types_size no longer equals btf->nr_types and the growth
path is not taken anymore, so every following type is written past the end
of the array:
BUG: unable to handle page fault for address: ffffc90006200000
RIP: 0010:btf_add_type+0x74/0x270
Call Trace:
btf_check_all_metas
btf_parse_module
Bound both the array size and the limit check by BTF_MAX_TYPE - start_id.
Base BTF (start_id == 0) is unaffected.
Fixes: 951bb64621b8 ("bpf: Add in-kernel split BTF support")
Signed-off-by: Feng Yang <yangfeng@kylinos.cn>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Mahe Tardy <mahe.tardy@gmail.com>
Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://patch.msgid.link/20261028031933.277550-1-yangfeng59949@163.com
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An open-coded iterator can return a struct pointer borrowed from its
current element. The verifier has not tied such results to iterator
state since the task_vma iterator was introduced, so a saved result
can still be used after destroy. Commit bee9ef4a40a27 ("bpf: switch
task_vma iterator from mmap_lock to per-VMA locks") also made next
release the protection of the prior element. A later snapshot
conversion made vm_file explicitly borrowed from that element.
Associate non-RCU, non-acquired struct results with the iterator
reference by default. Invalidate dependents before next forks its
NULL and non-NULL paths, while retaining the iterator itself. Let
destroy propagate child-reference errors. Add KF_ITER_RET_INDEPENDENT
for results that outlive the current element, preserving existing
RCU and acquired-reference rules.
Trusted pointer field loads also need to preserve the source lifetime.
Loading a trusted field does not acquire a reference to the pointed-to
object. Set the field pointer's parent_id to the source's reference ID
if the source is referenced, or inherit its parent_id if it is borrowed.
This is a generic rule, including accesses unrelated to iterators. For
example, the following access is now rejected:
file = bpf_get_task_exe_file(task);
if (!file)
return 0;
inode = file->f_inode;
bpf_put_file(file);
ino = inode->i_ino;
The inode pointer borrows the file's lifetime. Releasing the acquired
file reference removes that lifetime guarantee, so the verifier must
invalidate the derived inode pointer as well. This does not imply that
bpf_put_file() immediately frees the file or inode. Reading the inode
while the file reference is held remains valid. Fields with independent
RCU protection retain their existing lifetime rules.
For an iterator result, the same propagation keeps trusted fields such
as vm_file and f_inode tied to the current element. Propagate the backing
object's lifetime through dynptr construction too, so its descendants
remain in the invalidation graph. Share the invalidation traversal
between next and release, so advancing the iterator preserves its own
reference.
Fixes: 4ac454682158 ("bpf: Introduce task_vma open-coded iterator kfuncs")
Suggested-by: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Xu Yunxiang <xyx2021@mail.ustc.edu.cn>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Amery Hung <ameryhung@gmail.com>
Link: https://patch.msgid.link/20261024100647.2579244-2-xyx2021@mail.ustc.edu.cn
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btf_check_all_metas() ignores the return value of btf_add_type(), so a
type that could not be registered is silently dropped while the loop
keeps walking over the type section.
Both failure modes are reachable:
- -E2BIG. Once the types array reaches its capacity (BTF_MAX_TYPE),
every following btf_add_type() fails the same way, so
btf_check_all_metas() still returns 0 and the BTF object is created
with btf->nr_types capped while hdr->type_len claims more records.
- -ENOMEM. btf->nr_types is not incremented and the array is not
grown, so the next type is recorded at the slot of the dropped one
and btf->types[] stays off by one with respect to the type ids for
all remaining types. btf_type_by_id() then returns the wrong type
for those ids for the whole lifetime of the object, and the last
type is silently left unresolved.
Propagate the error so that the object is rejected instead.
Fixes: 69b693f0aefa ("bpf: btf: Introduce BPF Type Format (BTF)")
Signed-off-by: Feng Yang <yangfeng@kylinos.cn>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Mahe Tardy <mahe.tardy@gmail.com>
Acked-by: Alan Maguire <almagui@kernel.org>
Link: https://patch.msgid.link/20261022064727.747304-1-yangfeng59949@163.com
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A kernel struct shared with BPF programs may want to point at arena
memory, e.g. a sched_ext argument struct that the kernel builds in the
scheduler's arena and that refers to another arena object. A pointer
member reaches the program typed as a kernel pointer, so sched_ext
publishes a plain u64 holding a pre-translated arena address that the
program casts before use.
Translate in the verifier instead. When a load through a kernel struct
pointer lands on a member tagged __arena, btf_struct_walk() reports it
and the destination register becomes PTR_TO_ARENA. The member holds the
kernel address of the arena memory; the fixup pass appends the
conversion to the arena pointer form that the struct_ops trampoline
applies to __arena arguments, after a plain load or a load-acquire of
the member:
r1 = *(u64 *)(r2 + off)
if r1 == 0 goto +1 // __nullable members and probed loads
w1 -= lo32(kern_vm_start)
A probed load, through a plain or an untrusted pointer, keeps the NULL
test as well: it reads as 0 when it faults, and the subtraction must
not turn that into an arena pointer. An acquire load only comes through
a pointer that cannot fault.
Stores to kernel structs are rejected as before, and with them the
atomics that write such a member. A member
inside a multi-member union is rejected too: an offset into a union
resolves to its first member, so a program reading another member there
would receive an arena pointer it did not ask for. Loads through
program-allocated objects and program BTF are unaffected, there the tag
is what the compiler emits for the arena address space.
The rewrite is per insn while verification is per path, so the aux data
records what an insn loaded on any path: an insn that loaded an arena
pointer member on one path and a different member on another is
rejected by the fixup pass, while paths disagreeing only on __nullable
keep the NULL test, which a never-NULL member can afford. As for
__arena arguments, the program needs an associated arena, which also
supplies the base to subtract.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20261019132203.3034698-8-memxor@gmail.com
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A pointer member of a kernel struct that the verifier derives as trusted
or RCU-protected is assumed to be non-NULL, so a load through it is a
plain dereference. The BTF_TYPE_SAFE_*_OR_NULL lists exist for members
known to be NULL at times, but they live in the verifier and have to be
extended by hand.
Teach btf_struct_walk() to report the "nullable" BTF type tag on a
pointer member as PTR_MAYBE_NULL. The tag combines with any other tag
on the member; it only says that the pointer may be NULL. The verifier
keeps the flag where NULL would otherwise be assumed away: on trusted
and RCU results, which a program dereferences as they are, and on
per-CPU results, which the per-CPU helpers shift without a check. Such
a pointer has to be tested before it is dereferenced or passed on.
Plain and untrusted results are probed anyway and lose the flag, as the
BTF_TYPE_SAFE_*_OR_NULL lists never applied to them either, so a tagged
member of an existing struct asks no more of the programs that read it
than a list entry does, and the tag can take the place of the lists.
The next patch uses the tag on __arena members to decide whether the
injected address translation has to preserve NULL.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20261019132203.3034698-7-memxor@gmail.com
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btf_struct_show() and btf_array_show() recurse for every nested struct
and array. MAX_RESOLVE_DEPTH bounds one resolve walk when BTF is loaded,
not the nesting: a member whose type is resolved already is not walked
again, so BTF that defines its types from the inside out can nest them as
deep as it has types.
Whoever may load BTF, with CAP_BPF or a BPF token, can give such a type
to the value of a map. Reading the file of that map in bpffs then
overruns the kernel stack: with a few hundred levels the stack guard page
is hit and the kernel panics.
Stop at 32 levels. That is MAX_RESOLVE_DEPTH, and __btf_show_indent()
has as many columns. Nothing is shown for a member that lies deeper, and
the status becomes -E2BIG, which bpf_snprintf_btf() and
bpf_seq_printf_btf() return. The types of an x86_64 defconfig kernel nest
14 deep.
Fixes: b00b8daec828 ("bpf: btf: Add pretty print capability for data with BTF type info")
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20261017163745.3341787-19-alexei.starovoitov@gmail.com
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Validation logic allowed a BTF_KIND_LOC_PARAM with size <= 4
and vlen == 2, an inconsistent representation.
Fixes: a3df11403e8c8 ("bpf: Verify BTF_KIND_LOC_PARAM vlen, flags")
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20261012140640.2932195-2-alan.maguire@oracle.com
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Module .BTF.inline is split relative to its module BTF. For external
modules, module BTF can instead be split relative to a distilled
.BTF.base and is relocated against vmlinux when the module loads.
Parse ordinary module inline BTF relative to the pre-relocation
module BTF. Retain the module relocation ID and string maps, then
rebase inline type IDs and string offsets onto the final
vmlinux/module BTF space before exposing the result through sysfs.
Malformed or unrelocatable optional inline BTF is warned about and
omitted without preventing normal module BTF registration. The
btf_vmlinux_inline carrier remains on its existing hash-checked,
vmalloc-backed publishing path, preserving mmap support for
vmlinux.inline when delivered by a module.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20261009112324.1442319-6-alan.maguire@oracle.com
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Make btf_relocate() optionally return the string-offset map it builds
while relocating a BTF relative to a distilled base. A subsequent split
BTF object can use that map to rebase references to base strings.
Also account for the accumulated base string offset when assigning a
new BTF base. This is required when the base is itself split.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20261009112324.1442319-5-alan.maguire@oracle.com
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Expose BTF inline-location information from vmlinux .BTF.inline
sections in /sys/kernel/btf as vmlinux.inline. Embedded vmlinux
inline BTF supports read-only mmap().
Provide runtime support for a module-delivered vmlinux inline BTF
carrier. Its link record binds the carrier module name, BTF size, and
SHA-256 digest to the running kernel before its data is made available
through a lazy vmlinux.inline sysfs attribute. The carrier is handled
before ordinary module BTF registration, so its incidental .BTF data is
not exposed.
Make CONFIG_DEBUG_INFO_BTF_INLINE tristate. When configured as a
module, retain vmlinux final split inline BTF for
btf_vmlinux_inline.ko instead of embedding it in vmlinux.
Reserve .BTF.inline.link in vmlinux and extend the final
resolve_btfids patch pass to bind btf_vmlinux_inline to the raw
vmlinux.BTF.inline payload. This preserves the normal built-in
configuration while allowing the large inline BTF payload to load on
demand.
Normal module inline BTF is handled separately, after its
references have been relocated against the final module BTF.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20261009112324.1442319-4-alan.maguire@oracle.com
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Relax the requirements for reads like `p->arr[i].field`, where `p` is a
PTR_TO_BTF_ID, by allowing `i` to be a non-constant value.
This is useful for loops over arrays accessed from a PTR_TO_BTF_ID
when the verifier widens the loop induction variable.
Check that the access stays within array bounds based on the access
register's min and max bounds. Check that the access is aligned with
array elements using the register's `base` and `step`.
Technically, modify btf_struct_access() such that:
- it identifies `field` by walking BTF from the minimum offset
(the register's reg_smin + static instruction offset);
- it remembers which arrays contain `field`;
- it checks that offsets `k * step` stay within the array
and point to the same `field`;
- it does not check upper bounds for flexible arrays
(as is already the case for constant-offset access).
Support for flexible arrays nested inside trailing struct members
(e.g. p->nested.data[i], with data declared as int data[]) is left
for future work.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20261009-scev-minimal-rebase-v3-20-bcba9bc53ac9@gmail.com
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LLVM splits a static of a Rust program into pieces. Every piece is a VAR
with the type of the whole static:
[223] STRUCT 'BpfCell<core::option::Option<...>>' size=32 vlen=1
[236] VAR '..scx_cosmos9TASK_CTXS.0' type_id=223, linkage=static
[248] DATASEC '.bss' size=0 vlen=9
type_id=236 offset=24648 size=1 (VAR '..TASK_CTXS.0')
and the kernel rejects such BTF with "Invalid size".
Allow it. The size of a variable in DATASEC is used in two places:
- btf_find_datasec_var() looks for timers, spin locks, kptrs and other
special fields. btf_find_field_one() skips a variable when its size is
not the size of its type, so there are no special fields in a piece.
- btf_datasec_show() prints variables by their types. It would read
past the piece and past the end of the map value when the piece is the
last one. Don't print the pieces.
"global data test #8" and "#10" in prog_tests/btf.c expect "Invalid
size". BTF of both is loaded now. The map of #10 is not created, since
its value is larger than the section.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20261002124714.180012-10-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
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Some static functions in BTF of a Rust program have arguments without
names:
[71] FUNC_PROTO '(anon)' ret_type_id=0 vlen=1
'(anon)' type_id=72
[81] FUNC 'unwrap_failed' type_id=71 linkage=static
and the kernel rejects such BTF with "Invalid arg#1". It's 5 of 25
static functions in scx_cosmos and 6 of 24 in scx_simple.
The verifier looks at types of the arguments. The names are printed only,
as "(anon)" when there is none. Allow such static FUNC. Global functions
are checked as before.
The test "func (Some arg has no name)" in prog_tests/btf.c has a static
function. Make it global to keep the check.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/bpf/20261002124714.180012-8-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
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Names of types and functions in BTF that LLVM makes for a Rust program
are not C identifiers:
[69] STRUCT 'NonNull<str>' size=16 vlen=1
[147] FUNC 'write_fmt<scx_cosmos::BpfStream>' type_id=146
and the kernel rejects such BTF with "Invalid name". scx_simple and
scx_cosmos schedulers written in Rust have them in STRUCT, FWD and FUNC,
made of letters, digits and " #&()*,:;<>[]{}", 430 characters at most.
Allow any printable character in btf_name_valid_identifier(), like it's
done for DATASEC. It checks names of types, functions, members,
enumerators, variables and arguments, so all of them can have such
characters now. The limit of KSYM_NAME_LEN stays.
The name of FUNC is a part of the name of the program in kallsyms, where
a space would break the parsers. Replace what is not a character of
an identifier with '_' there.
Tests in prog_tests/btf.c expect "Invalid name" for names with '!' and
'*', which are valid now. Put a character that is not printable there.
The type name '?foo' is expected to load.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20261002124714.180012-6-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
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Ensure that vlen and flags combinations are consistent for
BTF_KIND_LOC_PARAMs.
Fixes: 33c5a3278bdb ("btf: Extend UAPI to support BTF location (inline site) info")
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20260926175113.2368566-2-alan.maguire@oracle.com
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Cross-merge BPF and other fixes after downstream PR.
Conflicts:
kernel/bpf/helpers.c
tools/testing/selftests/bpf/prog_tests/cb_refs.c
tools/testing/selftests/bpf/prog_tests/verifier.c
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Add BTF_KIND_LOC_PARAM, BTF_KIND_LOC_PROTO and BTF_KIND_LOCSEC
to help represent location information for functions.
BTF_KIND_LOC_PARAM is used to represent how we retrieve data at a
location; either via register(s), or register+offset, a dereference
of a register+offset or a constant value.
BTF_KIND_LOC_PROTO represents location information about a location
with multiple BTF_KIND_LOC_PARAMs.
And finally BTF_KIND_LOCSEC is a set of location sites, each
of which has
- a BTF_KIND_FUNC function associated with the inline site
- a location prototype specifying where to find the function
parameters
- an address offset relative to the kernel base address
This can be used to support representing
- a fully-inlined function at potentially multiple inline sites
with potentially different parameter availability
- a partially-inlined function where some _LOC_PROTOs represent
inlined sites as above and others have normal _FUNC representations
Also BTF_KIND_LOCSEC struct btf_loc will have two type id
references; one for the associated func, the other for the loc_proto.
Accordingly increase the number of m_offs references in btf_field_desc
to 2.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://patch.msgid.link/20260924111428.75957-2-alan.maguire@oracle.com
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BPF programs that manage their own objects have no way to run their own
logic once an RCU grace period has elapsed. bpf_obj_drop() defers a
free, but returning an index to an allocator or unpinning a resource
once readers are done has no equivalent. sched_ext's BPF library works
around this today by pushing freed nodes onto a list and having a
userspace thread call membarrier(MEMBARRIER_CMD_GLOBAL) and then run a
BPF program to reclaim them.
Add:
int bpf_call_rcu(struct bpf_rcu_head *rh, void *map,
int (*callback)(struct bpf_map *map, void *key,
void *value));
@rh is a struct bpf_rcu_head embedded in a value of @map, so the
callback runs as callback(map, key, value) for the element it lives in
and needs no cookie. A head can only be armed once, which bounds
outstanding work by the number of elements.
struct bpf_rcu_head holds the callback state inline rather than a
pointer to it, as bpf_timer, bpf_wq and bpf_task_work do, because there
is nothing to cancel and so nothing that has to outlive the map value.
That avoids an allocation and a state machine on the arming path at the
cost of 48 bytes per element.
An RCU callback cannot be cancelled, so everything it touches has to
stay alive until it runs:
- The callback is the program's text, so arming takes a program
reference as bpf_timer, bpf_wq and bpf_task_work do, dropped once
the callback returns. bpf_prog_inc_not_zero() also fails the arm
with -EBADF once the program is dying.
- The map is held by that reference through used_maps. An inner map
is not, so bpf_rcu_head is rejected in one.
- The field is only accepted in BPF_MAP_TYPE_ARRAY, whose elements
are never freed individually. A hash element can be deleted and
recycled while a callback is queued on it.
- The head is disarmed before the callback runs so it can be armed
again from there, which takes a new program reference before the
running callback drops its own. Arming therefore fails with -EPERM
once the map is held by neither a process nor bpffs.
bpf_iter hands a program a writable pointer to the live element, which
would let it overwrite a queued head, so bpf_iter_attach_map() rejects
maps carrying one.
The callback is verified non-sleepable even when the caller is
sleepable, and RCU invokes it with BH disabled.
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20260922200208.3203834-2-puranjay@kernel.org
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Allows programs to pass a context argument that points to a scalar
output value on to a kfunc that writes the result on the program's
behalf.
A ctx_arg_info entry can now describe a fixed-size PTR_TO_MEM context
argument through a new mem_size field, honored in btf_ctx_access().
Loading the argument yields a PTR_TO_MEM | MEM_RDONLY | PTR_TRUSTED
register of known size, readable but not writable by the program. A
kfunc argument tagged with the new "__ctx_out" suffix accepts only that
register type with a size matching the pointed-to type, so the only
value a program can pass is an output argument from its own context.
The pointer stays read-only to the program because the value is
trusted by whoever invoked the BPF program. In the first use case, the
inode_init_security LSM hook, every LSM receives a shared xattr array
and an int *xattr_count that lsm_get_xattr_slot() increments; a program
that could store a garbage count would push another LSM's write out of
bounds, so only the kfunc itself writes through it.
Suggested-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20260915150739.284189-4-daniel@iogearbox.net
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This patch adds necessary infrastructure to attach a struct_ops
map to a cgroup. The initial need was to support migrating
the legacy BPF_PROG_TYPE_SOCK_OPS to a struct_ops.
Recently, there are other struct_ops use cases that
need to attach struct_ops to a cgroup. For example,
the recent BPF OOM and memcg discussion in LSFMMBPF 2026.
The motivation is to create a consistent expectation
for attaching struct_ops to cgroup instead of each subsystem
creating its own infrastructure. This logic includes
hierarchy expectation, ordering expectation,
attachment API, and rcu gp.
There is already an existing implementation for attaching
multiple bpf progs to a cgroup. There are also tools
built around it for querying. Attaching a struct_ops map
(which is a group of bpf programs) could also adhere to
a similar API and potentially reuse most of the existing
implementation.
A couple of ideas have been tried. One of them
is to use mprog.c. In terms of the amount of changes,
I eventually came to the same conclusion as in
commit 120933984460 ("bpf: Implement mprog API on top of existing cgroup progs").
I then shifted the focus to reusing the current
{update,compute,activate,purge}_effective_progs() which has
the main logic that implements the mprog API.
Since then, I tried to add a 'struct cgroup *cgroup' member
to the existing 'struct bpf_struct_ops_link' and link_create
will create a 'struct bpf_struct_ops_link' object to be stored
in the pl->link. This turns out to have more changes on
both cgroup.c and bpf_struct_ops.c than I like.
This patch directly reuses the 'struct bpf_cgroup_link' which
cgroup.c already understands. Add 'struct bpf_map *map'
to 'struct bpf_cgroup_link'. In the future, as more subsystems
are extended by struct_ops, we may consider to make
'struct bpf_map *map' as a primary citizen of a link
like 'struct bpf_prog *prog' and directly add
'struct bpf_map *map' to the generic 'struct bpf_link'.
The pl->link could be the traditional 'prog' link or the
new 'map' link. The places that need to handle them differently
have already been refactored into the new prog_list_*() added in
the earlier patch. In those new prog_list_*(), this patch will
check "pl->link && pl->link->map", learn that it is a 'map' link
and handle it correctly.
The bpf_prog_array also needs to handle that its item can store
the traditional 'prog' or it can store a struct_ops map.
The places that need to handle them differently have also
been refactored into the new bpf_cgroup_array_*() added
in the earlier patch. The two differences are:
- different sentinel (dummy_bpf_prog in prog vs cfi_stub in struct_ops)
- the array for struct_ops may need to go through different
rcu gp.
The bpf_cgroup_array_*() functions use the cgroup_bpf_attach_type (ie atype)
to distinguish the array is storing prog or storing struct_ops map.
This patch also implements a separate struct bpf_link_ops
"cgroup_struct_ops_link_ops" to have a separate link_ops implementation
that only handles the cgroup's struct_ops link.
Questions:
- Although this patch did not change it, it is not obvious to me how
the replace_effective_progs() and purge_effective_progs() handle
cases when there are existing BPF_F_PREORDER progs attached
in the hlist.
Misc notes:
- CGROUP_TCP_SOCK_OPS is added to the 'enum cgroup_bpf_attach_type'.
The actual implementation of the tcp_bpf_ops (a struct_ops)
will be added in the next patch.
- free_after_mult_rcu_gp is added to 'struct bpf_struct_ops' such that
the bpf_prog_array can have a mix of sleepable and
non-sleepable prog in a struct_ops. This can tell
how the bpf_prog_array should be freed.
- For a struct_ops that supports cgroup attachment, it does not need to
implement its own reg/unreg function. reg/unreg to a cgroup is
done by the common infrastructure added in this patch.
- The cgroup's struct_ops link only supports BPF_F_ALLOW_MULTI.
This is enforced internally in cgroup_bpf_struct_ops_attach.
This should be consistent with the current prog's link
behavior in cgroup_bpf_link_attach.
In the future, we may allow each subsystem to choose differently.
- A cgroup_atype member is added to 'struct bpf_struct_ops'.
When a subsystem struct_ops needs to support cgroup attachment,
it needs to add a value to 'enum cgroup_bpf_attach_type'
and then assign it to the newly added cgroup_atype member
in the bpf_struct_ops.
- During LINK_CREATE in syscall, the patch uses the same
BPF_STRUCT_OPS (in attr->link_create.attach_type).
The bpf_struct_ops_link_create learns the map and
from the map it learns the st_ops. If the st_ops->cgroup_atype
is not 0, it will create a cgroup's link.
- When a subsystem registers a struct_ops that supports cgroup
attachment, the struct_ops infrastructure will also ask the
cgroup infrastructure to remember a few things. This is done
by calling cgroup_bpf_struct_ops_register().
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20260917200542.3689605-10-ameryhung@gmail.com
|
|
Program-allocated objects can own other local objects through referenced
kptrs. bpf_obj_free_fields() follows those pointers through
__bpf_obj_drop_impl() synchronously, before the object storage is freed
through RCU. A self-referential local kptr type therefore permits arbitrarily
deep object chains, and dropping the head can exhaust the kernel stack.
Long acyclic type chains have the same problem.
btf_check_and_fixup_fields() still assumes referenced kptrs only point to
kernel types and checks ownership through list and rbtree roots only. Its
existing rule is sufficient for graph-only cycles: the target of each graph
edge must contain a node, so every type in a cycle has both a root and a
node. The rule rejects such a type owning another root, breaking every
cycle. It also limits graph-only chains to three types, or two if the first
type contains a node, and conservatively rejects longer acyclic chains.
The missing local-kptr edges, rather than a missed graph-only cycle, are the
bug introduced by support for bpf_kptr_xchg() into local kptrs.
Replace that restriction with one bounded ownership walk covering graph
roots and local referenced kptrs. Run it after all BTF records have been
fixed up, reject cycles and paths deeper than eight record-bearing types,
and cache each type's suffix depth while checking it against the remaining
budget. This also permits the longer acyclic graph-only layouts rejected
by the old rule; update their existing BTF tests accordingly.
Keep the bound independent of MAX_CALL_FRAMES because recursive destruction
can run below a BPF call chain. A plain local pointee without special-field
metadata adds only a final non-recursing drop. Non-owning kptrs and
kernel-BTF kptrs do not recurse through local records and remain outside the
walk. Include local percpu-kptr edges too, although allocation of percpu
objects with special fields is currently forbidden, so that relaxing that
restriction cannot bypass the ownership bound.
btf_check_and_fixup_fields() continues to initialize graph_root.value_rec,
including for separately allocated map records. The ownership relationships
belong to immutable program BTF and only need validation at BTF load time.
Fixes: b0966c724584 ("bpf: Support bpf_kptr_xchg into local kptr")
Reported-by: Nicholas Carlini <npc@anthropic.com>
Suggested-by: Nicholas Carlini <npc@anthropic.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20260914132444.2564218-2-memxor@gmail.com
|
|
The previous patch refuses a kfunc argument of more than one eightbyte.
This patch allows up to 16 byte kfunc arguments.
But different architectures have different ways to map the BPF calling
convention (no gap, no backfill) to the native one. Rather than have each
arch open-code where it wants an argument, describe the convention with a
register count and four booleans, and let each arch set what applies to
it:
struct bpf_jit_arg_abi {
u8 nr_arg_regs;
bool even_reg_align;
bool even_stack_align;
bool split_at_boundary;
bool backfill_after_stack;
};
The four booleans are meant to cover x86-64, arm64, RISC-V LP64 and
PowerPC64 ELFv2, although only x86-64 and arm64 fill the struct in here.
bpf_jit_place_args() and bpf_jit_plan_arg_moves() use that description to
work out where each argument belongs and which slots the JIT then has to
move, to be used in the JIT later on.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260912195242.989416-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
A 128-bit integer follows the same calling convention as a 16-byte
by-value struct: LLVM emits it as a 16-byte BTF_KIND_INT and passes it in
two consecutive argument registers. So a __int128 gets its two slots.
The test added at the start of the series, which recorded the wrong
register map as an R4 !read_ok rejection, now passes and is flipped to
__success.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260912195227.987991-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
A global function taking a struct or union by value is rejected today:
Arg#1 type STRUCT in tar() is not supported yet.
Accept one of at most 16 bytes, which arrives in one or two consecutive
argument registers. Only structs composed entirely of scalars are taken
for now; btf_struct_is_composed_of() enforces that.
The slots of a value are independent of each other, so the compiler may
split one across the last argument register and the stack, as in
static void f(int a, int b, int c, int d, struct pair p);
or place it wholly past the registers, and the verifier describes either
the same way. What has to follow the slots is stack_arg_cnt, recomputed
from the slots consumed, together with the "no stack args in global
functions" and JIT support checks, and the MAX_BPF_FUNC_ARGS bound, which
now has to account for a parameter that takes two slots at once.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260912195221.987808-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
btf_prepare_func_args() indexes sub->args[] by BTF parameter, so a
parameter can only ever stand for a single argument register. Give the
loop a second index: 'i' keeps walking the BTF parameters while
'slots_used' walks the argument slots, and sub->arg_slot_cnt becomes the
number of slots, so that a later patch can give a parameter two of them.
No functional change: every parameter still takes exactly one slot.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260912195216.987189-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Rename arg_cnt to arg_slot_cnt, as a later patch gives a parameter that
takes two argument registers, an __int128 or a 16-byte aggregate, two
slots. No functional change.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260912195211.986081-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
ARG_DONTCARE is the zero-valued terminator for the fixed-size
helper argument array rather than an argument whose value is ignored.
Rename it to ARG_UNUSED and stop helper argument iteration explicitly
when it is encountered.
Commit c3fd8e5fd100 ("bpf: Reject non-scalar bpf_loop iteration
counts") introduced ARG_SCALAR for arguments that must be scalars.
Reuse it for integer and enum global subprogram arguments, which already
require SCALAR_VALUE despite being classified as ARG_ANYTHING, and for
exception callback arguments. This leaves ARG_ANYTHING with its legacy
helper behavior of accepting pointers when pointer leaks are allowed.
Also pass ARG_PTR_TO_MEM when checking a global subprogram memory
argument instead of using the prototype terminator as a placeholder.
No functional change.
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20260911220415.1396439-6-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
The alloc_obj_fields array is never modified. Make the array itself
const, not just the strings it points to.
Signed-off-by: Bradley Morgan <brads@mainlining.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260906223358.25717-1-brads@mainlining.org
|
|
When an access goes past the struct and the last member is a flexible
array, btf_struct_walk() folds the offset back into a single element with
(off - moff) % t->size, but never checks that the element type has a size.
BTF takes an empty struct, so this in program BTF
/* event could be empty */
struct event {
#ifdef HAVE_TIMESTAMP
__u64 ts;
#endif
};
struct batch {
int nr;
struct event events[];
};
divides by zero at prog load time. Getting there needs a PTR_TO_BTF_ID that
is not MEM_ALLOC, e.g. a plain read of a local kptr stashed in a map from a
sleepable program.
Oops: divide error: 0000 [#1] SMP KASAN PTI
RIP: 0010:btf_struct_walk+0x53f/0x1570
Call Trace:
<TASK>
btf_struct_access+0x42a/0xcd0
check_ptr_to_btf_access+0x4dc/0x1160
check_mem_access+0x3a45/0x8740
check_load_mem+0x36a/0xd10
do_check_common+0x3ef0/0xb210
bpf_check+0x6d3b/0x8580
bpf_prog_load+0xf7c/0x2720
__sys_bpf+0xa83/0x3690
__x64_sys_bpf+0xc7/0x150
x64_sys_call+0x1f3f/0x27e0
do_syscall_64+0xe5/0x610
entry_SYSCALL_64_after_hwframe+0x76/0x7e
</TASK>
Reject a zero-sized element type. The fixed array path in the same function
already bails out on the same thing:
btf_struct_walk()
...
/* skip empty array */
if (moff == mtrue_end)
continue;
msize /= total_nelems;
Fixes: 9c5f8a1008a1 ("bpf: Support variable length array in tracing programs")
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260910122316.186384-1-jiayuan.chen@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Cross-merge BPF and other fixes after downstream PR.
Conflicts:
kernel/bpf/backtrack.c
include/linux/bpf_verifier.h
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
When bpf_btf_find_by_name_kind() finds a type in module BTF, it
returns a new BTF object fd through __btf_new_fd(). This reaches
anon_inode_getfd(), which can sleep while allocating or expanding the
current task fd table.
The helper prototype does not set might_sleep, so the verifier allows
the helper in non-sleepable contexts such as BPF timer callbacks. The
fd allocation can then sleep in softirq context and install the fd into
the interrupted task.
Mark the helper as sleepable. This preserves calls from the main body
of a sleepable syscall program while rejecting calls from its
non-sleepable regions.
Fixes: 3d78417b60fb ("bpf: Add bpf_btf_find_by_name_kind() helper.")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Link: https://lore.kernel.org/bpf/20260903155150.D57251F000E9@smtp.kernel.org
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260903214758.2727663-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
do_wait() passes wo->wo_pid to the sched_process_wait tracepoint.
kernel_wait4() leaves wo_pid NULL for wait4(-1), and
kernel_waitid_prepare() does likewise for waitid(P_ALL).
btf_ctx_access() currently types argument 0 as PTR_TO_BTF_ID |
PTR_TRUSTED. Without PTR_MAYBE_NULL, the verifier accepts an unchecked
dereference. Trusted pointer loads have no fault protection, so a wait for
any child can then cause a NULL pointer dereference in JITed BPF code.
Add sched_process_wait to raw_tp_null_args[] with argument 0 marked
nullable. The verifier rejects an unchecked dereference while preserving
access after the program checks the pointer for NULL.
Fixes: 838a10bd2ebf ("bpf: Augment raw_tp arguments with PTR_MAYBE_NULL")
Reported-by: Nicholas Carlini <npc@anthropic.com>
Suggested-by: Nicholas Carlini <npc@anthropic.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260903144433.1716731-8-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
The signal_generate and signal_deliver tracepoints declare their info
argument as a struct kernel_siginfo pointer. btf_ctx_access() therefore
treats it as a trusted pointer for tp_btf programs.
Signal delivery also uses SEND_SIG_NOINFO and SEND_SIG_PRIV as special
values for this argument. Those values are zero and one respectively,
and are not pointers. A tp_btf program can currently dereference either
value and fault the kernel. In particular, signal_generate can run from
timer interrupt context, turning the fault into a kernel panic.
Record both tracepoints in raw_tp_null_args[] and mark argument one as
a non-pointer. This preserves scalar access to the cookie while rejecting
direct and helper-mediated pointer use. Merely marking it nullable would
not suffice because SEND_SIG_PRIV is nonzero.
Fixes: 838a10bd2ebf ("bpf: Augment raw_tp arguments with PTR_MAYBE_NULL")
Reported-by: Nicholas Carlini <npc@anthropic.com>
Suggested-by: Nicholas Carlini <npc@anthropic.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260903144433.1716731-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
btf_var_show() calls btf_type_id_resolve() unconditionally, which
dereferences btf->resolved_ids. That is NULL for a base BTF - e.g. the
vmlinux BTF that bpf_snprintf_btf() renders against - since base BTF is
not resolved during parsing. btf_modifier_show() guards this with
'if (btf->resolved_ids)', but btf_var_show() does not.
A BPF program that passes the type_id of a BTF_KIND_VAR from the vmlinux
BTF to bpf_snprintf_btf() thus NULL-derefs:
KASAN: probably user-memory-access in range [0x46638-0x4663f]
RIP: 0010:btf_var_show (kernel/bpf/btf.c:2929)
Call Trace:
<TASK>
btf_type_show (kernel/bpf/btf.c:8259)
btf_type_snprintf_show (kernel/bpf/btf.c:8329)
bpf_snprintf_btf (kernel/trace/bpf_trace.c:1047)
bpf_prog_test_run_raw_tp (net/bpf/test_run.c:829)
__sys_bpf (kernel/bpf/syscall.c:4804)
do_syscall_64 (arch/x86/entry/syscall_64.c:84)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
</TASK>
Resolve the var's type directly with btf_type_skip_modifiers() when
resolved_ids is NULL, mirroring btf_modifier_show().
Fixes: c4d0bfb45068 ("bpf: Add bpf_snprintf_btf helper")
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260901104924.346187-4-jiayuan.chen@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
btf_modifier_show() resolves the modifier and then calls
btf_type_ops(t)->show() unconditionally. For the void type (type_id 0,
BTF_KIND_UNKN) kind_ops[] has no entry, so ->show is NULL.
A "const void" (a modifier resolving to void) cannot be a map key or
value - map_check_btf() rejects it because void has no size - so the map
dump path does not reach it. But bpf_snprintf_btf() takes a type_id
straight from the BPF program, and passing such a "const void" from the
vmlinux BTF NULL-derefs:
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
RIP: 0010:btf_modifier_show (kernel/bpf/btf.c:2914)
Call Trace:
<TASK>
btf_type_show (kernel/bpf/btf.c:8251)
btf_type_snprintf_show (kernel/bpf/btf.c:8321)
bpf_snprintf_btf (kernel/trace/bpf_trace.c:1047)
bpf_prog_test_run_raw_tp (net/bpf/test_run.c:829)
__sys_bpf (kernel/bpf/syscall.c:4804)
do_syscall_64 (arch/x86/entry/syscall_64.c:94)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
</TASK>
Fall back to btf_df_show() when the resolved type has no show op; it
emits the "<unsupported kind:N>" placeholder already used for kinds like
FWD and FUNC. bpf_snprintf_btf() then returns the length as usual.
Fixes: c4d0bfb45068 ("bpf: Add bpf_snprintf_btf helper")
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260901104924.346187-3-jiayuan.chen@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
A global function may already return an arena pointer on its own, and
check_global_ret_scalar_reg() accepts one in either half of the R0:R2
pair. Let the members of a by-value struct it returns be arena pointers
as well, rather than scalars only.
Only a subprogram gets this: the main program returns to the kernel,
which has no arena to cast the address back into, so
btf_validate_return_type() keeps rejecting an arena pointer there,
whether bare or inside a struct. The rejection message therefore has to
name what the function at hand may return, or it would offer the main
program an arena pointer it cannot have.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260829061550.1696869-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
btf_struct_member_walk() hardcodes that every member of a struct returned
by value must be a scalar. A later patch needs the same walk to also
accept arena pointers, so give it a mask of the member kinds it allows.
The mask reaches callers through btf_struct_is_composed_of(), which
replaces btf_type_is_scalar_struct() as the entry point exported to
btf.c. btf_type_is_scalar_struct() stays as a verifier-local wrapper for
the call sites that only ever ask about scalars.
There is no functional change: btf_member_kind_allowed() is exactly
btf_type_is_scalar() when the mask is BTF_MEMBER_SCALAR alone, and the
shared check is the last statement of the loop body, so dropping the array
branch's continue neither skips a member nor checks one twice.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260829061534.1693789-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Add btf_type_is_arena_ptr() to test whether a BTF type is a pointer
carrying the "arena" type tag, and use it to simplify both
btf_scan_type_tags() and btf_validate_return_type(). The helper has
external linkage because a later patch calls it from verifier.c to
decide whether a struct member returned by value may be an arena
pointer.
btf_scan_type_tags() drove btf_type_tag_walk() with a one-entry match
table, so the "multiple type tags" error it checked for could never
fire: btf_type_tag_walk() only fails when the walk sets more than one
flag. Dropping that error path, and with it the int return, is
therefore no functional change.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260829061529.1693266-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
btf_type_is_scalar_struct() recurses into nested struct members and
carries the nesting depth in a @rec argument, so every caller has to
spell out the 0 that starts the walk.
Move the recursion into btf_struct_member_walk() and leave
btf_type_is_scalar_struct() as a thin wrapper over it. This is
groundwork for the later patches, which give the walk further state
that callers should not have to supply: the kinds of member it accepts,
and a record of the member that made it fail.
No functional change.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260829061524.1692957-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Relax btf_distill_func_proto() to accept a by-value struct or union that
the R0:R2 convention added in earlier patches can carry:
- a struct or union larger than 8 and up to 16 bytes, returned in the
R0:R2 register pair, matching what LLVM emits for the BPF target;
- a struct or union up to 8 bytes, returned in R0 alone.
A >8 byte scalar (__int128) was already accepted and is unchanged.
Everything else stays rejected: a return type larger than 16 bytes, and any
type that __get_type_size() cannot return in registers at all (e.g. an
array), which it already reports as ret < 0.
btf_validate_return_type() is relaxed as well, so that it accepts a
by-value struct or union up to 16 bytes in addition to void and scalars.
With btf_distill_func_proto() and btf_validate_return_type() relaxed, the
verifier, JIT, precision-backtracking and live-register support from the
earlier patches becomes reachable: <=16 byte aggregate return values now
work end to end.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://patch.msgid.link/20260819055314.3298664-1-yonghong.song@linux.dev
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
|
|
LLVM 23 added support for returning a value in two registers for an
__int128, or a struct/union whose size is greater than 8 but not more than
16 bytes. See LLVM patches [1] and [2].
Before LLVM 23 the BPF backend could not return these values at all. A
by-value struct or union return (of any size) was rejected at compile time
with:
error: aggregate returns are not supported
and an __int128 return failed later in the backend with:
fatal error: error in backend: unable to allocate function return #1
Both are resolved in LLVM 23, which lowers such returns into the R0:R2
register pair.
Model that pair at calls to global and static BPF subprograms and at kfunc
calls: R2 is marked alongside R0 at the call, propagated out of a callee
at its exit, and held to the same scalar-only and no-stack-pointer rules
that already apply to R0. A struct returned by a kfunc must be composed of
scalars, since its bytes reach the program as raw register contents and a
pointer field would otherwise be laundered into a scalar.
An extension program is the one caller of the convention that cannot take
part in it: only R0 is checked at its exit, since that is the program exit
code, so it has no way to hand back an upper half. Replacing a function
whose return value is larger than 8 bytes is therefore rejected in
btf_check_func_type_match(). That function compares btf_type->info, which
carries no size for an int, so an 8 byte long and a 16 byte __int128
compared equal; sizes up to 8 bytes stay interchangeable, as they always
have been, so this only rejects what the R0:R2 convention newly makes
incompatible.
[1] https://github.com/llvm/llvm-project/pull/190894
[2] https://github.com/llvm/llvm-project/pull/206876
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://patch.msgid.link/20260819055309.3297684-1-yonghong.song@linux.dev
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Pull bpf updates from Daniel Borkmann:
"Major changes:
- Redesign the verifier error reporting: failures now carry source
and instruction annotations along with the causal event history
that led to them, making program rejections far easier to debug and
repair (Kumar Kartikeya Dwivedi)
- Add arena argument support to kfuncs and struct_ops through the new
__arena and __arena__nullable suffixes (Tejun Heo, Puranjay Mohan,
Kumar Kartikeya Dwivedi, Ihor Solodrai)
- Signed BPF program loader rework to accommodate both BPF and
security community needs where the kernel runs the signature
verification at BPF_PROG_LOAD time before the LSM admission hook
(Daniel Borkmann)
- Add a set of ksock kfuncs which let BPF LSM and syscall programs
create, connect and send on UDP sockets in order to emit telemetry
data (Mahe Tardy)
- Unify helper and kfunc call argument verification and classify
kfunc arguments purely from BTF into a generated bpf_func_proto
which is computed once at add-call time (Amery Hung)
Other features and fixes:
- Enable EXECMEM_ROX_CACHE for BPF allocations on x86 (Mike Rapoport)
- Add bidirectional VLAN support to bpf_fib_lookup() through the new
BPF_FIB_LOOKUP_VLAN and BPF_FIB_LOOKUP_VLAN_INPUT flags (Avinash
Duduskar)
- Infer zext_dst from static register liveness analysis to fix 32-bit
zero-extension semantics, and remove the artificial limitations on
pointer types eligible for spilling (Eduard Zingerman)
- Inline the numeric open-coded iterator kfuncs so that bpf_for()
loops no longer pay a kfunc call on every iteration (Puranjay
Mohan)
- Add an arena-based bitmap data structure to libarena along with
serial and parallel selftests (Emil Tsalapatis)
- Teach resolve_btfids to discover kfuncs from the kernel's BTF ID
sets and to emit kfunc BTF decl tags, reducing the kernel build's
dependency on pahole features (Ihor Solodrai)
- Add BPF_F_ADJ_ROOM_DECAP_* flags to bpf_skb_adjust_room() so that
tunnel decapsulation can update the GSO and encapsulation state of
the skb (Nick Hudson)
- Fix the ring buffer pending_pos walk and the available-data
accounting on 32-bit position wrap (Israel Téllez García)
- Add memory usage accounting for arena maps and fix an mmap_lock
deadlock on arena lock failure (Jiayuan Chen)
- Add tracing_multi link info support to the kernel UAPI and bpftool,
and refactor the stack map code to run with preemption disabled
(Jiri Olsa)
- Support BPF_F_EGRESS in bpf_redirect_peer() to emit the skb in the
egress direction of the target's peer device (Jordan Rife)
- Add a KF_SPINLOCK_SAFE kfunc flag so that providers, in particular
modules, can declare kfuncs safe to call under bpf_spin_lock
instead of relying on the verifier's hard-coded allowlist (Kaitao
Cheng)
- Introduce global percpu data for BPF programs with libbpf probing
and bpftool skeleton support, and stop exposing uninitialized
kernel heap memory when copying per-CPU map values (Leon Hwang)
- Add s390 JIT support for load-acquire and store-release
instructions (Maxim Khmelevskii)
- Fix a CFI mismatch in the task work callback and an arm64 KASAN
false positive after bpf_throw() (Mykyta Yatsenko)
- Reject writes through untrusted BTF pointers and bound the
rdonly/rdwr_buf_size kfunc arguments (Nicholas Dudar)
- Invalidate RCU pointers only after the final spin unlock and
account for preempt and IRQ disabled regions as overlapping RCU
protection (Ning Ding)
- Support mixing bpf2bpf calls and tail calls on RV64, add signed
operations and 32-bit atomics to the RV32 JIT, and add timed
may_goto support (Pu Lehui, Kuan-Wei Chiu, Feng Jiang)
- Fix a use-after-free on mm_struct in bpf_find_vma() for foreign
tasks and an mmap_lock leak in the irq_work path (Sanghyun Park)
- Populate mmap-able BPF array map memory lazily which makes mmap()
O(1) instead of proportional to the map size (Song Liu)
- Introduce a jit_required flag and reject programs with inlined
helpers when no JIT is available, where the interpreter would
otherwise jump into an invalid address (Tiezhu Yang)
- Fix the x86 JIT per-CPU address resolution into an extended
register where the REX prefix dropped the high destination register
bit (Vineet Gupta)
- Reject MEM_ALLOC BTF accesses past object bounds, arena frees below
the arena base, and mixed arena and ordinary atomic paths (Yiyang
Chen)
- Fix the trampoline handling of 128-bit arguments and of return
values larger than 8 bytes (Yonghong Song)
- Ensure that any fault prone load is rewritten with exception table
handling, and fix the arena load-acquire and atomic fetch handling
in the x86, arm64, riscv and s390 JITs (Daniel Borkmann)
- Many more fixes and cleanups across the verifier, arena,
trampolines, sockmap, cgroup, ring buffer, x86/arm64/riscv/s390
JITs, libbpf, bpftool, resolve_btfids and selftests"
* tag 'bpf-next-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (373 commits)
selftests/bpf: Add tests for a store on a fault prone qdisc pointer
selftests/bpf: Add tests for fault prone loads out of RCU pointers
selftests/bpf: Add tests for pointer type merge at a shared load
selftests/bpf: Remove duplicate copies of the arena spinlock qnodes
selftests/bpf: Retry stat generation in cgroup_iter_memcg
selftests/bpf: Test pseudo-function policy diagnostics
bpf: Distinguish function references in policy diagnostics
bpf: Preserve source attribution without source text
selftests/bpf: Test kfunc argument diagnostics
bpf: Correct kfunc argument diagnostics
bpf: Use canonical stack argument names in diagnostics
bpf: Preserve R0 lineage across helper calls
selftests/bpf: Exercise negative optlen in cgroup getsockopt hook
bpf: Reject negative optlen in cgroup getsockopt hook
selftests/bpf: tc_tunnel - validate decap GSO and encapsulation state
bpf: Clear decap state on skb_adjust_room shrink path
bpf: Allow new DECAP flags and add guard rails
bpf: Add BPF_F_ADJ_ROOM_DECAP_* flags for tunnel decapsulation
bpf: Refactor masks for ADJ_ROOM flags and encap validation
bpf: Name the enum for BPF_FUNC_skb_adjust_room flags
...
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git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing updates from Steven Rostedt:
- Expose btf_ids to trace events
In order to allow BPF programs to attach to system call trace events
(which are actually pseudo trace events built on top of raw_syscall
events), expose the BTF ID of the events. This will allow BPF
programs better precision in attaching to events.
- Use "u64" to assign to hist_field->type
Instead of using kstrdup("u64", GFP_KERNEL) to assign the
hist_field->type, just point it to "u64" instead. The
hist_field->type is freed via kfree_const().
- Replace kmalloc()/strcpy() with kstrdup() for trace_printk
Instead of having two calls to copy the module format string, just
use kstrdup().
- Use __free() in trace event histograms and triggres where possible
- Use seq_buf in trace event code instead of strcat()
Instead of calculating the size of the buffer to use and filling it
with strcat(), use the seq_buf infrastructure that takes care of
making sure not to overflow the string size.
- Reject invalid preemptirq_delay_test CPU affinity
The preempt_delay_test module can take an invalid CPU affinity mask
and create confusing output. Simply have the module reject invalid
affinity masks.
- Prevent division by zero in ftrace_ops sample module code
If the ftrace_ops sample module code receives the module parameter
nr_function_calls set to zero, it can cause a division by zero error.
- Warn when an event dereferences a parameter in TP_printk()
On boot up and module load, the trace event TP_printk() is scanned
for possible bugs. As the TP_printk() code is executed when the user
reads the "trace" file and processes the data written when the
trace_event executed, the data it reads can be literally days old.
The scan currently checks for dereferencing printk formats like
"%pI6". But it does not check if the parameters themselves have a
dereference like:
TP_printk("offset %08x: value %08x",
(u32)(__entry->addr - __entry->edma->membase), __entry->value)
__entry represents the pointer to the event on the ring buffer. The
__entry->edma->membase is dereferencing a pointer on the ring buffer
to find membase, but the __entry->edma may no longer be a valid
pointer.
Warn on this case too.
- Replace some strcpy() with strscpy()
- Clean up mmiotrace events to use assign_type() macro
The assign_type() macro makes sure the event type is indeed the type
that is being parsed. The mmiotrace trace was written before that
macro was created so it just simply typecasted the pointer.
Replace the typecasting with the macro.
- Have the ENUM processing to numbers only process what is added
The code that converts ENUMs to their numbers in the trace events
scanned all events to do the processing. This was true when a module
was loaded too. That is, instead of processing just the events for
the module, it processed *all* events. Even the builtin ones that
were processed at boot up.
Add a check for the event->module matching mod if it is a module
before processing it.
* tag 'trace-v7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (21 commits)
tracing: Have trace_event_update_all() only handle module that is loading
tracing: Cleanup event_enable_trigger_parse() by using __free()
tracing: Report every TP_printk double dereference
tracing/mmiotrace: Use trace_assign_type() in mmio_print_mark()
tracing: Make per-template BTF id lists file-local
tracing: Use seq_buf for string concatenation
tracing: Use strscpy() instead of strcpy() in trace_sched_switch
tracing: Warn when an event dereferences a pointer in TP_printk()
samples/ftrace: Prevent division by zero when nr_function_calls is zero
tracing: Reject invalid preemptirq_delay_test CPU affinity
fgraph: Use trace_seq_putc() in print_graph_return()
tracing/user_events: Replace a seq_printf() call by seq_puts() in user_seq_show()
tracing/user_events: Use seq_putc() in two functions
tracing: Bound histogram expression strings with seq_buf
tracing: Return ERR_PTR() from expr_str()
tracing: Use __free() for expr_str() buffer
kernel/trace/trace_printk: Use kstrdup() instead of kmalloc() and strcpy()
tracing: Point constant hist field type to string literal
selftests/bpf: Add test for tracepoint btf_ids tracefs file
tracing: Expose tracepoint BTF ids via tracefs
...
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The Call Type Safety diagnostics mishandle three kfunc argument classes.
BTF type ID 0 represents void, but btf_show_name() also uses zero to end
type traversal. A pointer that resolves to void therefore loses its pointee
name and is rendered as "()". End traversal directly for concrete terminal
types, but resolve referenced types before testing for ID zero, and name the
void terminal type explicitly. Format the complete parameter pointer type
for nullable kfunc arguments, so void pointers are reported as (void *).
Also add the missing structured report when an __szk memory-size argument is
not a verifier-known constant. Describe the generic bpf_refcount_acquire()
contract without deriving an object type from its void pointer prototype.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/668871823f90f69896d3db27b56db2f53e481162.camel@gmail.com
Link: https://lore.kernel.org/bpf/20260816015746.2632990-7-memxor@gmail.com
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Teach verifier diagnostics to annotate an instruction with BTF source
line information and nearby BPF instructions. The renderer keeps source
text in a fixed-width lane and prints instructions in a stable right-hand
gutter.
Wrap annotation text under the source line so long error labels remain
readable while the source and instruction lanes keep their fixed layout.
Keeping source and instruction context in one commit preserves the visual
layout contract that later diagnostic reports rely on.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://patch.msgid.link/20260815064612.378577-3-memxor@gmail.com
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
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There are many adjacent blank lines in kernel/bpf/ that have accumulated
over time.
Drop them for cleanup.
No functional changes intended.
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/bpf/20260813152324.97937-2-leon.hwang@linux.dev
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It was an effort to enhance fscache as a kernel cache for lazy
pulling (at least according to previous Incremental FS discussion [1])
and EROFS over fscache was the in-tree user of this mode.
fscache has since evolved to be netfslib-oriented, serving network
filesystem inodes via the netfs library, but EROFS never acts as a
network filesystem and we need to cache golden filesystem images rather
than individual EROFS inodes.
Since EROFS over fscache is now removed, clean up netfs/fscache/
cachefiles upstream too.
[1] https://lore.kernel.org/r/CAOQ4uxi4dzxArY24YO=+kBCK2gGoq3Ptb8WkzCqSogPgU_R3dQ@mail.gmail.com
[dh] Fixed up comments on:
https://sashiko.dev/#/patchset/20260716103030.3065561-1-dhowells%40redhat.com
https://sashiko.dev/#/patchset/20260722130218.78958-1-dhowells%40redhat.com
Signed-off-by: Gao Xiang <xiang@kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/1046393.1786544127@warthog.procyon.org.uk
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-erofs@lists.ozlabs.org
cc: bpf@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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A struct_ops callback cannot receive an arena pointer directly, so
passing one takes two steps. The pointer arrives as a bare u64 that the
callback casts, and because the two sides address the arena through
different bases it also has to be rebased by hand on the way in.
Add the __arena and __arena__nullable stub argument suffixes to make this
convenient. The callback declares the parameter as an arena pointer,
receives it as a PTR_TO_ARENA register, and dereferences it directly,
while the kernel caller just passes the natural kernel arena address
(kaddr). The trampoline converts the value while saving the arguments
into the BPF ctx, ctx[slot] = (u32)(kaddr - kern_vm_start), so the
program never sees a kernel address and nothing rewrites the ctx after
the fact. The converted value keeps the upper 32 bits clear as the JITs
require of arena pointer registers and behaves like any cast_kern'ed
arena pointer, so cast_user recovers the full user-visible address.
__arena converts unconditionally and the kernel caller must not pass
NULL. __arena__nullable preserves NULL, tested on the full 64-bit kernel
pointer, and surfaces to the verifier as PTR_TO_ARENA (but not as a
PTR_TO_ARENA | PTR_MAYBE_NULL). The reason is that PTR_TO_ARENA in the
program's type state already encompasses NULL-ness, so it is not
meaningful to force a NULL check for the program.
The composite suffix intentionally ends in __nullable. Classify
__arena__nullable before the generic suffix so scalar arena pointees do
not take the generic nullable BTF pointer path.
This patch adds the generic side. prepare_arg_info() records arena and
nullable argument flags in the struct_ops function model, and
bpf_tramp_arena_base() returns the arena base for a single-program
struct_ops indirect trampoline. Only that trampoline converts: its
program's arena is fixed at generation time. Generic trampolines can mix
programs with different arenas and reject arena context arguments
defensively, which is unreachable today as only struct_ops programs
carry them. Architectures that do not implement the conversion are
gated out at verification time with bpf_jit_supports_arena_args().
Co-developed-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://patch.msgid.link/20260808003938.3486067-6-memxor@gmail.com
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
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Passing an arena pointer to a kfunc takes two steps today. There is no
arena pointer argument type, so the pointer crosses the boundary as a
bare scalar, and the kfunc then offsets it by the arena base and casts
it before it can touch the memory. Every such kfunc open-codes the same
translation.
Add the __arena and __arena__nullable argument suffixes to make this more
convenient. The kfunc declares the parameter by its real pointer type
and dereferences it directly, with the JIT rebasing the value at the
call site, rN = kern_vm_start + (u32)rN. No bounds check is needed: the
u32 offset stays within the guard-padded arena kernel mapping, and a
fault on an unpopulated page recovers through the per-arena scratch
page. A suffixed argument accepts a PTR_TO_ARENA or scalar register,
matching global subprog arena arguments.
__arena rebases unconditionally, so the kfunc never sees NULL and a
value with zero in the low 32 bits arrives as the arena base.
__arena__nullable preserves NULL for optional arguments by skipping the
rebase when the truncated value, arena offset 0, is zero. Keeping the
plain form NULL-free saves the NULL test on every call.
The double separator makes the annotations composable:
__arena__nullable also ends in __nullable and naturally follows the
common nullable argument path. Plain __arena follows that path too for
verifier type checking because both forms accept a constant zero; the
function-model flag still determines whether the JIT preserves NULL or
rebases it to the arena base.
This patch adds the verifier side: the suffixes are recognized in
check_kfunc_args() and distilled into argument flags in the function
model stored in the kfunc descriptor. JITs retrieve the model while
emitting the call, avoiding per-call state in insn_aux_data.
JITs declare support with bpf_jit_supports_arena_args() and verification
fails with -ENOTSUPP elsewhere.
Co-developed-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://patch.msgid.link/20260808003938.3486067-5-memxor@gmail.com
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
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Commit 814cba835ef6 ("bpf, x86: Fix trampoline stack size for 128-bit
arguments") changed the x86 trampoline to compute the number of
registers from arg_size for every argument, which removed the last user
of BTF_FMODEL_STRUCT_ARG. No other architecture or verifier code looks
at the flag, so remove the macro and the code in __get_type_fmodel_flags()
which sets it.
Keep BTF_FMODEL_SIGNED_ARG at BIT(1) rather than renumbering it to
BIT(0), so BIT(0) is available for a future flag.
No functional change.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Leon Hwang <leon.hwang@linux.dev>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20260803052726.2821447-1-yonghong.song@linux.dev
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