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bpf: Improve check_raw_mode_ok test for MEM_UNINIT-tagged types

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When checking malformed helper function signatures, also take other argument
types into account aside from just ARG_PTR_TO_UNINIT_MEM.

This concerns (formerly) ARG_PTR_TO_{INT,LONG} given uninitialized memory can
be passed there, too.

The func proto sanity check goes back to commit 435faee1aa ("bpf, verifier:
add ARG_PTR_TO_RAW_STACK type"), and its purpose was to detect wrong func protos
which had more than just one MEM_UNINIT-tagged type as arguments.

The reason more than one is currently not supported is as we mark stack slots with
STACK_MISC in check_helper_call() in case of raw mode based on meta.access_size to
allow uninitialized stack memory to be passed to helpers when they just write into
the buffer.

Probing for base type as well as MEM_UNINIT tagging ensures that other types do not
get missed (as it used to be the case for ARG_PTR_TO_{INT,LONG}).

Fixes: 57c3bb725a ("bpf: Introduce ARG_PTR_TO_{INT,LONG} arg types")
Reported-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20240913191754.13290-4-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Daniel Borkmann 2024-09-13 21:17:49 +02:00 committed by Alexei Starovoitov
parent 32556ce93b
commit 18752d73c1
1 changed files with 11 additions and 5 deletions
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16
kernel/bpf/verifier.c
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@ -8291,6 +8291,12 @@ static bool arg_type_is_mem_size(enum bpf_arg_type type)
type == ARG_CONST_SIZE_OR_ZERO;
}
static bool arg_type_is_raw_mem(enum bpf_arg_type type)
{
return base_type(type) == ARG_PTR_TO_MEM &&
type & MEM_UNINIT;
}
static bool arg_type_is_release(enum bpf_arg_type type)
{
return type & OBJ_RELEASE;
@ -9340,15 +9346,15 @@ static bool check_raw_mode_ok(const struct bpf_func_proto *fn)
{
int count = 0;
if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM)
if (arg_type_is_raw_mem(fn->arg1_type))
count++;
if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM)
if (arg_type_is_raw_mem(fn->arg2_type))
count++;
if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM)
if (arg_type_is_raw_mem(fn->arg3_type))
count++;
if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM)
if (arg_type_is_raw_mem(fn->arg4_type))
count++;
if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM)
if (arg_type_is_raw_mem(fn->arg5_type))
count++;
/* We only support one arg being in raw mode at the moment,