diff options
| author | Yonghong Song <yonghong.song@linux.dev> | 2024-11-12 08:39:33 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-11-12 16:26:25 -0800 |
| commit | 5bd36da1e37e7a78e8b38efd287de6e1394b7d6e (patch) | |
| tree | 44a082b24b2c227d10d755f17d5e44d7504a5491 /kernel/bpf | |
| parent | f4b295ab65980435d7dc8b12d110387d1d1c653c (diff) | |
bpf: Support private stack for struct_ops progs
For struct_ops progs, whether a particular prog uses private stack
depends on prog->aux->priv_stack_requested setting before actual
insn-level verification for that prog. One particular implementation
is to piggyback on struct_ops->check_member(). The next patch has
an example for this. The struct_ops->check_member() sets
prog->aux->priv_stack_requested to be true which enables private stack
usage.
The struct_ops prog follows the same rule as kprobe/tracing progs after
function bpf_enable_priv_stack(). For example, even a struct_ops prog
requests private stack, it could still use normal kernel stack if
the stack size is small (< 64 bytes).
Similar to tracing progs, nested same cpu same prog run will be skipped.
A field (recursion_detected()) is added to bpf_prog_aux structure.
If bpf_prog->aux->recursion_detected is implemented by the struct_ops
subsystem and nested same cpu/prog happens, the function will be
triggered to report an error, collect related info, etc.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20241112163933.2224962-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/trampoline.c | 4 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 7 |
2 files changed, 10 insertions, 1 deletions
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 9f36c049f4c2..a8d188b31da5 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -899,6 +899,8 @@ static u64 notrace __bpf_prog_enter_recur(struct bpf_prog *prog, struct bpf_tram if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) { bpf_prog_inc_misses_counter(prog); + if (prog->aux->recursion_detected) + prog->aux->recursion_detected(prog); return 0; } return bpf_prog_start_time(); @@ -975,6 +977,8 @@ u64 notrace __bpf_prog_enter_sleepable_recur(struct bpf_prog *prog, if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) { bpf_prog_inc_misses_counter(prog); + if (prog->aux->recursion_detected) + prog->aux->recursion_detected(prog); return 0; } return bpf_prog_start_time(); diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 176d19ad9d07..f4c39bb50511 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6110,7 +6110,7 @@ static enum priv_stack_mode bpf_enable_priv_stack(struct bpf_prog *prog) case BPF_PROG_TYPE_TRACING: case BPF_PROG_TYPE_LSM: case BPF_PROG_TYPE_STRUCT_OPS: - if (bpf_prog_check_recur(prog)) + if (prog->aux->priv_stack_requested || bpf_prog_check_recur(prog)) return PRIV_STACK_ADAPTIVE; fallthrough; default: @@ -22053,6 +22053,11 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) } } + if (prog->aux->priv_stack_requested && !bpf_jit_supports_private_stack()) { + verbose(env, "Private stack not supported by jit\n"); + return -EACCES; + } + /* btf_ctx_access() used this to provide argument type info */ prog->aux->ctx_arg_info = st_ops_desc->arg_info[member_idx].info; |