diff options
| author | Kumar Kartikeya Dwivedi <memxor@gmail.com> | 2022-12-07 21:41:39 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-12-09 03:39:28 +0100 |
| commit | f6ee298fa140f6b5bae3acf6d6108741278bcced (patch) | |
| tree | 9fc9780595282f7affe32b2f2c2095bfd28ae6f7 /kernel | |
| parent | bpf: Rework check_func_arg_reg_off (diff) | |
| download | linux-f6ee298fa140f6b5bae3acf6d6108741278bcced.tar.xz linux-f6ee298fa140f6b5bae3acf6d6108741278bcced.zip | |
bpf: Move PTR_TO_STACK alignment check to process_dynptr_func
After previous commit, we are minimizing helper specific assumptions
from check_func_arg_reg_off, making it generic, and offloading checks
for a specific argument type to their respective functions called after
check_func_arg_reg_off has been called.
This allows relying on a consistent set of guarantees after that call
and then relying on them in code that deals with registers for each
argument type later. This is in line with how process_spin_lock,
process_timer_func, process_kptr_func check reg->var_off to be constant.
The same reasoning is used here to move the alignment check into
process_dynptr_func. Note that it also needs to check for constant
var_off, and accumulate the constant var_off when computing the spi in
get_spi, but that fix will come in later changes.
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221207204141.308952-6-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 8a7e964bcc31..9791788071d5 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5932,6 +5932,14 @@ int process_dynptr_func(struct bpf_verifier_env *env, int regno, verbose(env, "verifier internal error: misconfigured dynptr helper type flags\n"); return -EFAULT; } + /* CONST_PTR_TO_DYNPTR already has fixed and var_off as 0 due to + * check_func_arg_reg_off's logic. We only need to check offset + * alignment for PTR_TO_STACK. + */ + if (reg->type == PTR_TO_STACK && (reg->off % BPF_REG_SIZE)) { + verbose(env, "cannot pass in dynptr at an offset=%d\n", reg->off); + return -EINVAL; + } /* MEM_UNINIT - Points to memory that is an appropriate candidate for * constructing a mutable bpf_dynptr object. * @@ -6301,11 +6309,6 @@ int check_func_arg_reg_off(struct bpf_verifier_env *env, switch (type) { /* Pointer types where both fixed and variable offset is explicitly allowed: */ case PTR_TO_STACK: - if (arg_type_is_dynptr(arg_type) && reg->off % BPF_REG_SIZE) { - verbose(env, "cannot pass in dynptr at an offset\n"); - return -EINVAL; - } - fallthrough; case PTR_TO_PACKET: case PTR_TO_PACKET_META: case PTR_TO_MAP_KEY: |