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authorAlexei Starovoitov <ast@kernel.org>2022-11-25 14:06:17 -0800
committerAndrii Nakryiko <andrii@kernel.org>2022-11-30 15:33:48 -0800
commitc67cae551f0df80421b5703ee56ff5e2fe9c4de6 (patch)
treecc1878eacd432087d36231fd8669971a5e963c70 /kernel/bpf/verifier.c
parent996c060e2bb90e5caef42849846b56da21ea88d9 (diff)
bpf: Tighten ptr_to_btf_id checks.
The networking programs typically don't require CAP_PERFMON, but through kfuncs like bpf_cast_to_kern_ctx() they can access memory through PTR_TO_BTF_ID. In such case enforce CAP_PERFMON. Also make sure that only GPL programs can access kernel data structures. All kfuncs require GPL already. Also remove allow_ptr_to_map_access. It's the same as allow_ptr_leaks and different name for the same check only causes confusion. Fixes: fd264ca02094 ("bpf: Add a kfunc to type cast from bpf uapi ctx to kernel ctx") Fixes: 50c6b8a9aea2 ("selftests/bpf: Add a test for btf_type_tag "percpu"") Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20221125220617.26846-1-alexei.starovoitov@gmail.com
Diffstat (limited to 'kernel/bpf/verifier.c')
-rw-r--r--kernel/bpf/verifier.c17
1 files changed, 14 insertions, 3 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 4e7f1d085e53..d0ecc0b18b20 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4703,6 +4703,18 @@ static int check_ptr_to_btf_access(struct bpf_verifier_env *env,
u32 btf_id;
int ret;
+ if (!env->allow_ptr_leaks) {
+ verbose(env,
+ "'struct %s' access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n",
+ tname);
+ return -EPERM;
+ }
+ if (!env->prog->gpl_compatible && btf_is_kernel(reg->btf)) {
+ verbose(env,
+ "Cannot access kernel 'struct %s' from non-GPL compatible program\n",
+ tname);
+ return -EINVAL;
+ }
if (off < 0) {
verbose(env,
"R%d is ptr_%s invalid negative access: off=%d\n",
@@ -4823,9 +4835,9 @@ static int check_ptr_to_map_access(struct bpf_verifier_env *env,
t = btf_type_by_id(btf_vmlinux, *map->ops->map_btf_id);
tname = btf_name_by_offset(btf_vmlinux, t->name_off);
- if (!env->allow_ptr_to_map_access) {
+ if (!env->allow_ptr_leaks) {
verbose(env,
- "%s access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n",
+ "'struct %s' access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n",
tname);
return -EPERM;
}
@@ -16679,7 +16691,6 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr)
env->allow_ptr_leaks = bpf_allow_ptr_leaks();
env->allow_uninit_stack = bpf_allow_uninit_stack();
- env->allow_ptr_to_map_access = bpf_allow_ptr_to_map_access();
env->bypass_spec_v1 = bpf_bypass_spec_v1();
env->bypass_spec_v4 = bpf_bypass_spec_v4();
env->bpf_capable = bpf_capable();