diff options
author | Alexei Starovoitov <ast@kernel.org> | 2022-11-26 01:06:17 +0300 |
---|---|---|
committer | Andrii Nakryiko <andrii@kernel.org> | 2022-12-01 02:33:48 +0300 |
commit | c67cae551f0df80421b5703ee56ff5e2fe9c4de6 (patch) | |
tree | cc1878eacd432087d36231fd8669971a5e963c70 | |
parent | 996c060e2bb90e5caef42849846b56da21ea88d9 (diff) | |
download | linux-c67cae551f0df80421b5703ee56ff5e2fe9c4de6.tar.xz |
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
-rw-r--r-- | include/linux/bpf.h | 5 | ||||
-rw-r--r-- | include/linux/bpf_verifier.h | 1 | ||||
-rw-r--r-- | kernel/bpf/verifier.c | 17 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/btf_type_tag_percpu.c | 1 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/verifier/map_ptr.c | 8 |
5 files changed, 19 insertions, 13 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 67452103bb86..4920ac252754 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1909,11 +1909,6 @@ static inline bool bpf_allow_uninit_stack(void) return perfmon_capable(); } -static inline bool bpf_allow_ptr_to_map_access(void) -{ - return perfmon_capable(); -} - static inline bool bpf_bypass_spec_v1(void) { return perfmon_capable(); diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index c05aa6e1f6f5..b5090e89cb3f 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -531,7 +531,6 @@ struct bpf_verifier_env { bool explore_alu_limits; bool allow_ptr_leaks; bool allow_uninit_stack; - bool allow_ptr_to_map_access; bool bpf_capable; bool bypass_spec_v1; bool bypass_spec_v4; 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(); diff --git a/tools/testing/selftests/bpf/progs/btf_type_tag_percpu.c b/tools/testing/selftests/bpf/progs/btf_type_tag_percpu.c index 8feddb8289cf..38f78d9345de 100644 --- a/tools/testing/selftests/bpf/progs/btf_type_tag_percpu.c +++ b/tools/testing/selftests/bpf/progs/btf_type_tag_percpu.c @@ -64,3 +64,4 @@ int BPF_PROG(test_percpu_helper, struct cgroup *cgrp, const char *path) return 0; } +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/verifier/map_ptr.c b/tools/testing/selftests/bpf/verifier/map_ptr.c index 1f82021429bf..17ee84dc7766 100644 --- a/tools/testing/selftests/bpf/verifier/map_ptr.c +++ b/tools/testing/selftests/bpf/verifier/map_ptr.c @@ -9,7 +9,7 @@ }, .fixup_map_array_48b = { 1 }, .result_unpriv = REJECT, - .errstr_unpriv = "bpf_array access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN", + .errstr_unpriv = "access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN", .result = REJECT, .errstr = "R1 is bpf_array invalid negative access: off=-8", }, @@ -26,7 +26,7 @@ }, .fixup_map_array_48b = { 3 }, .result_unpriv = REJECT, - .errstr_unpriv = "bpf_array access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN", + .errstr_unpriv = "access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN", .result = REJECT, .errstr = "only read from bpf_array is supported", }, @@ -41,7 +41,7 @@ }, .fixup_map_array_48b = { 1 }, .result_unpriv = REJECT, - .errstr_unpriv = "bpf_array access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN", + .errstr_unpriv = "access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN", .result = REJECT, .errstr = "cannot access ptr member ops with moff 0 in struct bpf_map with off 1 size 4", .flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS, @@ -57,7 +57,7 @@ }, .fixup_map_array_48b = { 1 }, .result_unpriv = REJECT, - .errstr_unpriv = "bpf_array access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN", + .errstr_unpriv = "access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN", .result = ACCEPT, .retval = 1, }, |