From: Kumar Kartikeya Dwivedi <[email protected]> Introduce support for KF_ARG_PTR_TO_TIMER. The kfuncs will use bpf_timer as argument and that will be recognized as timer argument by verifier. bpf_timer_kern casting can happen inside kfunc, but using bpf_timer in argument makes life easier for users who work with non-kern type in BPF progs.
Fix up process_timer_func's meta argument usage (ignore if NULL) so that we can share the same checks for helpers and kfuncs. meta argument is only needed to ensure bpf_timer_init's timer and map arguments are coming from the same map (map_uid logic is necessary for correct inner-map handling). No such concerns will be necessary for kfuncs as timer initialization happens using helpers, hence pass NULL to process_timer_func from kfunc argument handling code to ignore it. Signed-off-by: Kumar Kartikeya Dwivedi <[email protected]> Signed-off-by: Benjamin Tissoires <[email protected]> --- changes in v6: - used Kumar's version of the patch - reverted `+BTF_ID(struct, bpf_timer_kern)` changes in v5: - also check for the reg offset changes in v4: - enforce KF_ARG_PTR_TO_TIMER to be of type PTR_TO_MAP_VALUE new in v3 (split from v2 02/10) --- kernel/bpf/verifier.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ca6cacf7b42f..ccfe9057d8dc 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7568,12 +7568,16 @@ static int process_timer_func(struct bpf_verifier_env *env, int regno, val + reg->off, map->record->timer_off); return -EINVAL; } + /* meta is only needed for bpf_timer_init to match timer and map */ + if (!meta) + goto out; if (meta->map_ptr) { verbose(env, "verifier bug. Two map pointers in a timer helper\n"); return -EFAULT; } meta->map_uid = reg->map_uid; meta->map_ptr = map; +out: return 0; } @@ -10826,6 +10830,7 @@ enum { KF_ARG_LIST_NODE_ID, KF_ARG_RB_ROOT_ID, KF_ARG_RB_NODE_ID, + KF_ARG_TIMER_ID, }; BTF_ID_LIST(kf_arg_btf_ids) @@ -10834,6 +10839,7 @@ BTF_ID(struct, bpf_list_head) BTF_ID(struct, bpf_list_node) BTF_ID(struct, bpf_rb_root) BTF_ID(struct, bpf_rb_node) +BTF_ID(struct, bpf_timer_kern) static bool __is_kfunc_ptr_arg_type(const struct btf *btf, const struct btf_param *arg, int type) @@ -10877,6 +10883,11 @@ static bool is_kfunc_arg_rbtree_node(const struct btf *btf, const struct btf_par return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_NODE_ID); } +static bool is_kfunc_arg_timer(const struct btf *btf, const struct btf_param *arg) +{ + return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_TIMER_ID); +} + static bool is_kfunc_arg_callback(struct bpf_verifier_env *env, const struct btf *btf, const struct btf_param *arg) { @@ -10946,6 +10957,7 @@ enum kfunc_ptr_arg_type { KF_ARG_PTR_TO_NULL, KF_ARG_PTR_TO_CONST_STR, KF_ARG_PTR_TO_MAP, + KF_ARG_PTR_TO_TIMER, }; enum special_kfunc_type { @@ -11102,6 +11114,9 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env, if (is_kfunc_arg_map(meta->btf, &args[argno])) return KF_ARG_PTR_TO_MAP; + if (is_kfunc_arg_timer(meta->btf, &args[argno])) + return KF_ARG_PTR_TO_TIMER; + if ((base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)])) { if (!btf_type_is_struct(ref_t)) { verbose(env, "kernel function %s args#%d pointer type %s %s is not supported\n", @@ -11735,6 +11750,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ case KF_ARG_PTR_TO_CALLBACK: case KF_ARG_PTR_TO_REFCOUNTED_KPTR: case KF_ARG_PTR_TO_CONST_STR: + case KF_ARG_PTR_TO_TIMER: /* Trusted by default */ break; default: @@ -12021,6 +12037,15 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ if (ret) return ret; break; + case KF_ARG_PTR_TO_TIMER: + if (reg->type != PTR_TO_MAP_VALUE) { + verbose(env, "arg#%d doesn't point to a map value\n", i); + return -EINVAL; + } + ret = process_timer_func(env, regno, NULL); + if (ret < 0) + return ret; + break; } } -- 2.44.0
