From: Andrii Nakryiko <andrii@kernel.org> mainline inclusion from mainline-v6.12-rc1 commit 496ddd19a0fad22f250fc7a7b7a8000155418934 category: feature bugzilla: https://atomgit.com/openeuler/kernel/issues/8335 CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... ---------------------------------------------------------------------- Verifier enforces that all iterator structs are named `bpf_iter_<name>` and that whenever iterator is passed to a kfunc it's passed as a valid PTR -> STRUCT chain (with potentially const modifiers in between). We'll need this check for upcoming changes, so instead of duplicating the logic, extract it into a helper function. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240808232230.2848712-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Luo Gengkun <luogengkun2@huawei.com> --- include/linux/btf.h | 5 +++++ kernel/bpf/btf.c | 50 ++++++++++++++++++++++++++++++++------------- 2 files changed, 41 insertions(+), 14 deletions(-) diff --git a/include/linux/btf.h b/include/linux/btf.h index f477f7e23ca3..3dad546d37aa 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -580,6 +580,7 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, int get_kern_ctx_btf_id(struct bpf_verifier_log *log, enum bpf_prog_type prog_type); bool btf_types_are_same(const struct btf *btf1, u32 id1, const struct btf *btf2, u32 id2); +int btf_check_iter_arg(struct btf *btf, const struct btf_type *func, int arg_idx); #else static inline const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id) @@ -654,6 +655,10 @@ static inline bool btf_types_are_same(const struct btf *btf1, u32 id1, { return false; } +static inline int btf_check_iter_arg(struct btf *btf, const struct btf_type *func, int arg_idx) +{ + return -EOPNOTSUPP; +} #endif static inline bool btf_type_is_struct_ptr(struct btf *btf, const struct btf_type *t) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 3fe2b93b50bc..a3918dd19331 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7968,15 +7968,44 @@ BTF_ID_LIST_GLOBAL(btf_tracing_ids, MAX_BTF_TRACING_TYPE) BTF_TRACING_TYPE_xxx #undef BTF_TRACING_TYPE +/* Validate well-formedness of iter argument type. + * On success, return positive BTF ID of iter state's STRUCT type. + * On error, negative error is returned. + */ +int btf_check_iter_arg(struct btf *btf, const struct btf_type *func, int arg_idx) +{ + const struct btf_param *arg; + const struct btf_type *t; + const char *name; + int btf_id; + + if (btf_type_vlen(func) <= arg_idx) + return -EINVAL; + + arg = &btf_params(func)[arg_idx]; + t = btf_type_skip_modifiers(btf, arg->type, NULL); + if (!t || !btf_type_is_ptr(t)) + return -EINVAL; + t = btf_type_skip_modifiers(btf, t->type, &btf_id); + if (!t || !__btf_type_is_struct(t)) + return -EINVAL; + + name = btf_name_by_offset(btf, t->name_off); + if (!name || strncmp(name, ITER_PREFIX, sizeof(ITER_PREFIX) - 1)) + return -EINVAL; + + return btf_id; +} + static int btf_check_iter_kfuncs(struct btf *btf, const char *func_name, const struct btf_type *func, u32 func_flags) { u32 flags = func_flags & (KF_ITER_NEW | KF_ITER_NEXT | KF_ITER_DESTROY); - const char *name, *sfx, *iter_name; - const struct btf_param *arg; + const char *sfx, *iter_name; const struct btf_type *t; char exp_name[128]; u32 nr_args; + int btf_id; /* exactly one of KF_ITER_{NEW,NEXT,DESTROY} can be set */ if (!flags || (flags & (flags - 1))) @@ -7987,28 +8016,21 @@ static int btf_check_iter_kfuncs(struct btf *btf, const char *func_name, if (nr_args < 1) return -EINVAL; - arg = &btf_params(func)[0]; - t = btf_type_skip_modifiers(btf, arg->type, NULL); - if (!t || !btf_type_is_ptr(t)) - return -EINVAL; - t = btf_type_skip_modifiers(btf, t->type, NULL); - if (!t || !__btf_type_is_struct(t)) - return -EINVAL; - - name = btf_name_by_offset(btf, t->name_off); - if (!name || strncmp(name, ITER_PREFIX, sizeof(ITER_PREFIX) - 1)) - return -EINVAL; + btf_id = btf_check_iter_arg(btf, func, 0); + if (btf_id < 0) + return btf_id; /* sizeof(struct bpf_iter_<type>) should be a multiple of 8 to * fit nicely in stack slots */ + t = btf_type_by_id(btf, btf_id); if (t->size == 0 || (t->size % 8)) return -EINVAL; /* validate bpf_iter_<type>_{new,next,destroy}(struct bpf_iter_<type> *) * naming pattern */ - iter_name = name + sizeof(ITER_PREFIX) - 1; + iter_name = btf_name_by_offset(btf, t->name_off) + sizeof(ITER_PREFIX) - 1; if (flags & KF_ITER_NEW) sfx = "new"; else if (flags & KF_ITER_NEXT) -- 2.34.1