diff options
| author | Alexei Starovoitov <ast@kernel.org> | 2023-04-03 21:50:28 -0700 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2023-04-04 16:57:24 -0700 |
| commit | afeebf9f57a4965e0be90e4dc87f8f3a1417376d (patch) | |
| tree | 679061f4657f58b3e59255e932f081f25d4018d5 /kernel/bpf/verifier.c | |
| parent | 30ee9821f9430c34a6254134a5f0e8db227510be (diff) | |
bpf: Undo strict enforcement for walking untagged fields.
The commit 6fcd486b3a0a ("bpf: Refactor RCU enforcement in the verifier.")
broke several tracing bpf programs. Even in clang compiled kernels there are
many fields that are not marked with __rcu that are safe to read and pass into
helpers, but the verifier doesn't know that they're safe. Aggressively marking
them as PTR_UNTRUSTED was premature.
Fixes: 6fcd486b3a0a ("bpf: Refactor RCU enforcement in the verifier.")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230404045029.82870-8-alexei.starovoitov@gmail.com
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index fd90ba498ccc..56f569811f70 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4974,6 +4974,11 @@ static bool is_rcu_reg(const struct bpf_reg_state *reg) return reg->type & MEM_RCU; } +static void clear_trusted_flags(enum bpf_type_flag *flag) +{ + *flag &= ~(BPF_REG_TRUSTED_MODIFIERS | MEM_RCU); +} + static int check_pkt_ptr_alignment(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int off, int size, bool strict) @@ -5602,8 +5607,8 @@ static int check_ptr_to_btf_access(struct bpf_verifier_env *env, } else if (flag & (MEM_PERCPU | MEM_USER)) { /* keep as-is */ } else { - /* walking unknown pointers yields untrusted pointer */ - flag = PTR_UNTRUSTED; + /* walking unknown pointers yields old deprecated PTR_TO_BTF_ID */ + clear_trusted_flags(&flag); } } else { /* @@ -5617,7 +5622,7 @@ static int check_ptr_to_btf_access(struct bpf_verifier_env *env, } } else { /* Old compat. Deprecated */ - flag &= ~PTR_TRUSTED; + clear_trusted_flags(&flag); } if (atype == BPF_READ && value_regno >= 0) |