From 3ca1032ab7ab010eccb107aa515598788f7d93bb Mon Sep 17 00:00:00 2001 From: KP Singh Date: Fri, 6 Nov 2020 10:37:43 +0000 Subject: bpf: Implement get_current_task_btf and RET_PTR_TO_BTF_ID The currently available bpf_get_current_task returns an unsigned integer which can be used along with BPF_CORE_READ to read data from the task_struct but still cannot be used as an input argument to a helper that accepts an ARG_PTR_TO_BTF_ID of type task_struct. In order to implement this helper a new return type, RET_PTR_TO_BTF_ID, is added. This is similar to RET_PTR_TO_BTF_ID_OR_NULL but does not require checking the nullness of returned pointer. Signed-off-by: KP Singh Signed-off-by: Alexei Starovoitov Acked-by: Song Liu Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20201106103747.2780972-6-kpsingh@chromium.org --- kernel/trace/bpf_trace.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'kernel/trace') diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 4517c8b66518..e4515b0f62a8 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1022,6 +1022,20 @@ const struct bpf_func_proto bpf_get_current_task_proto = { .ret_type = RET_INTEGER, }; +BPF_CALL_0(bpf_get_current_task_btf) +{ + return (unsigned long) current; +} + +BTF_ID_LIST_SINGLE(bpf_get_current_btf_ids, struct, task_struct) + +static const struct bpf_func_proto bpf_get_current_task_btf_proto = { + .func = bpf_get_current_task_btf, + .gpl_only = true, + .ret_type = RET_PTR_TO_BTF_ID, + .ret_btf_id = &bpf_get_current_btf_ids[0], +}; + BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx) { struct bpf_array *array = container_of(map, struct bpf_array, map); @@ -1265,6 +1279,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_get_current_pid_tgid_proto; case BPF_FUNC_get_current_task: return &bpf_get_current_task_proto; + case BPF_FUNC_get_current_task_btf: + return &bpf_get_current_task_btf_proto; case BPF_FUNC_get_current_uid_gid: return &bpf_get_current_uid_gid_proto; case BPF_FUNC_get_current_comm: -- cgit From 8e4597c627fb48f361e2a5b012202cb1b6cbcd5e Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Thu, 12 Nov 2020 13:13:13 -0800 Subject: bpf: Allow using bpf_sk_storage in FENTRY/FEXIT/RAW_TP This patch enables the FENTRY/FEXIT/RAW_TP tracing program to use the bpf_sk_storage_(get|delete) helper, so those tracing programs can access the sk's bpf_local_storage and the later selftest will show some examples. The bpf_sk_storage is currently used in bpf-tcp-cc, tc, cg sockops...etc which is running either in softirq or task context. This patch adds bpf_sk_storage_get_tracing_proto and bpf_sk_storage_delete_tracing_proto. They will check in runtime that the helpers can only be called when serving softirq or running in a task context. That should enable most common tracing use cases on sk. During the load time, the new tracing_allowed() function will ensure the tracing prog using the bpf_sk_storage_(get|delete) helper is not tracing any bpf_sk_storage*() function itself. The sk is passed as "void *" when calling into bpf_local_storage. This patch only allows tracing a kernel function. Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Acked-by: Song Liu Link: https://lore.kernel.org/bpf/20201112211313.2587383-1-kafai@fb.com --- include/net/bpf_sk_storage.h | 2 ++ kernel/trace/bpf_trace.c | 5 +++ net/core/bpf_sk_storage.c | 74 ++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 81 insertions(+) (limited to 'kernel/trace') diff --git a/include/net/bpf_sk_storage.h b/include/net/bpf_sk_storage.h index 3c516dd07caf..0e85713f56df 100644 --- a/include/net/bpf_sk_storage.h +++ b/include/net/bpf_sk_storage.h @@ -20,6 +20,8 @@ void bpf_sk_storage_free(struct sock *sk); extern const struct bpf_func_proto bpf_sk_storage_get_proto; extern const struct bpf_func_proto bpf_sk_storage_delete_proto; +extern const struct bpf_func_proto bpf_sk_storage_get_tracing_proto; +extern const struct bpf_func_proto bpf_sk_storage_delete_tracing_proto; struct bpf_local_storage_elem; struct bpf_sk_storage_diag; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index e4515b0f62a8..cfce60ad1cb5 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include @@ -1735,6 +1736,10 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_skc_to_tcp_request_sock_proto; case BPF_FUNC_skc_to_udp6_sock: return &bpf_skc_to_udp6_sock_proto; + case BPF_FUNC_sk_storage_get: + return &bpf_sk_storage_get_tracing_proto; + case BPF_FUNC_sk_storage_delete: + return &bpf_sk_storage_delete_tracing_proto; #endif case BPF_FUNC_seq_printf: return prog->expected_attach_type == BPF_TRACE_ITER ? diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c index fd416678f236..359908a7d3c1 100644 --- a/net/core/bpf_sk_storage.c +++ b/net/core/bpf_sk_storage.c @@ -6,6 +6,7 @@ #include #include #include +#include #include #include #include @@ -378,6 +379,79 @@ const struct bpf_func_proto bpf_sk_storage_delete_proto = { .arg2_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON, }; +static bool bpf_sk_storage_tracing_allowed(const struct bpf_prog *prog) +{ + const struct btf *btf_vmlinux; + const struct btf_type *t; + const char *tname; + u32 btf_id; + + if (prog->aux->dst_prog) + return false; + + /* Ensure the tracing program is not tracing + * any bpf_sk_storage*() function and also + * use the bpf_sk_storage_(get|delete) helper. + */ + switch (prog->expected_attach_type) { + case BPF_TRACE_RAW_TP: + /* bpf_sk_storage has no trace point */ + return true; + case BPF_TRACE_FENTRY: + case BPF_TRACE_FEXIT: + btf_vmlinux = bpf_get_btf_vmlinux(); + btf_id = prog->aux->attach_btf_id; + t = btf_type_by_id(btf_vmlinux, btf_id); + tname = btf_name_by_offset(btf_vmlinux, t->name_off); + return !!strncmp(tname, "bpf_sk_storage", + strlen("bpf_sk_storage")); + default: + return false; + } + + return false; +} + +BPF_CALL_4(bpf_sk_storage_get_tracing, struct bpf_map *, map, struct sock *, sk, + void *, value, u64, flags) +{ + if (!in_serving_softirq() && !in_task()) + return (unsigned long)NULL; + + return (unsigned long)____bpf_sk_storage_get(map, sk, value, flags); +} + +BPF_CALL_2(bpf_sk_storage_delete_tracing, struct bpf_map *, map, + struct sock *, sk) +{ + if (!in_serving_softirq() && !in_task()) + return -EPERM; + + return ____bpf_sk_storage_delete(map, sk); +} + +const struct bpf_func_proto bpf_sk_storage_get_tracing_proto = { + .func = bpf_sk_storage_get_tracing, + .gpl_only = false, + .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, + .arg1_type = ARG_CONST_MAP_PTR, + .arg2_type = ARG_PTR_TO_BTF_ID, + .arg2_btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON], + .arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL, + .arg4_type = ARG_ANYTHING, + .allowed = bpf_sk_storage_tracing_allowed, +}; + +const struct bpf_func_proto bpf_sk_storage_delete_tracing_proto = { + .func = bpf_sk_storage_delete_tracing, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_CONST_MAP_PTR, + .arg2_type = ARG_PTR_TO_BTF_ID, + .arg2_btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON], + .allowed = bpf_sk_storage_tracing_allowed, +}; + struct bpf_sk_storage_diag { u32 nr_maps; struct bpf_map *maps[]; -- cgit From 6f100640ca5b2a2ff67b001c9fd3de21f7b12cf2 Mon Sep 17 00:00:00 2001 From: KP Singh Date: Fri, 13 Nov 2020 00:59:30 +0000 Subject: bpf: Expose bpf_d_path helper to sleepable LSM hooks Sleepable hooks are never called from an NMI/interrupt context, so it is safe to use the bpf_d_path helper in LSM programs attaching to these hooks. The helper is not restricted to sleepable programs and merely uses the list of sleepable hooks as the initial subset of LSM hooks where it can be used. Signed-off-by: KP Singh Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20201113005930.541956-3-kpsingh@chromium.org --- kernel/trace/bpf_trace.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'kernel/trace') diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index cfce60ad1cb5..02986c7b90eb 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -16,6 +16,8 @@ #include #include #include +#include + #include #include @@ -1179,7 +1181,11 @@ BTF_SET_END(btf_allowlist_d_path) static bool bpf_d_path_allowed(const struct bpf_prog *prog) { - return btf_id_set_contains(&btf_allowlist_d_path, prog->aux->attach_btf_id); + if (prog->type == BPF_PROG_TYPE_LSM) + return bpf_lsm_is_sleepable_hook(prog->aux->attach_btf_id); + + return btf_id_set_contains(&btf_allowlist_d_path, + prog->aux->attach_btf_id); } BTF_ID_LIST_SINGLE(bpf_d_path_btf_ids, struct, path) -- cgit