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Date: Tue, 21 Jan 2020 13:35:22 -0700
From: Matt Cover <werekraken@...il.com>
To: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
Andrii Nakryiko <andriin@...com>,
"David S. Miller" <davem@...emloft.net>,
Shuah Khan <shuah@...nel.org>,
Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
Jakub Sitnicki <jakub@...udflare.com>,
Quentin Monnet <quentin.monnet@...ronome.com>,
Matthew Cover <matthew.cover@...ckpath.com>,
Stanislav Fomichev <sdf@...gle.com>,
Andrey Ignatov <rdna@...com>,
Lorenz Bauer <lmb@...udflare.com>, netdev@...r.kernel.org,
bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-kselftest@...r.kernel.org,
Pablo Neira Ayuso <pablo@...filter.org>,
Jozsef Kadlecsik <kadlec@...filter.org>,
Florian Westphal <fw@...len.de>, coreteam@...filter.org
Subject: Re: [PATCH bpf-next v2 1/2] bpf: add bpf_ct_lookup_{tcp,udp}() helpers
On Tue, Jan 21, 2020 at 1:20 PM Matthew Cover <werekraken@...il.com> wrote:
>
> Allow looking up an nf_conn. This allows eBPF programs to leverage
> nf_conntrack state for similar purposes to socket state use cases,
> as provided by the socket lookup helpers. This is particularly
> useful when nf_conntrack state is locally available, but socket
> state is not.
>
> v2:
> - Fix functions in need of and missing static inline (kbuild)
> - Move tests to separate patch and submit as a series (John)
> - Improve clarity in helper documentation (John)
> - Add CONFIG_NF_CONNTRACK=m support (Daniel)
Sorry, missed additional maintainers for v2 changes.
+Pablo Neira Ayuso <pablo@...filter.org>
+Jozsef Kadlecsik <kadlec@...filter.org>
+Florian Westphal <fw@...len.de>
+coreteam@...filter.org
>
> Signed-off-by: Matthew Cover <matthew.cover@...ckpath.com>
> ---
> include/linux/bpf.h | 29 ++++
> include/linux/netfilter.h | 12 ++
> include/uapi/linux/bpf.h | 111 ++++++++++++++-
> kernel/bpf/verifier.c | 105 ++++++++++++++-
> net/core/filter.c | 277 ++++++++++++++++++++++++++++++++++++++
> net/netfilter/core.c | 16 +++
> net/netfilter/nf_conntrack_core.c | 1 +
> scripts/bpf_helpers_doc.py | 4 +
> tools/include/uapi/linux/bpf.h | 111 ++++++++++++++-
> 9 files changed, 658 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 8e3b8f4..f502e1f 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -239,6 +239,7 @@ enum bpf_arg_type {
> ARG_PTR_TO_LONG, /* pointer to long */
> ARG_PTR_TO_SOCKET, /* pointer to bpf_sock (fullsock) */
> ARG_PTR_TO_BTF_ID, /* pointer to in-kernel struct */
> + ARG_PTR_TO_NF_CONN, /* pointer to bpf_nf_conn */
> };
>
> /* type of values returned from helper functions */
> @@ -250,6 +251,7 @@ enum bpf_return_type {
> RET_PTR_TO_SOCKET_OR_NULL, /* returns a pointer to a socket or NULL */
> RET_PTR_TO_TCP_SOCK_OR_NULL, /* returns a pointer to a tcp_sock or NULL */
> RET_PTR_TO_SOCK_COMMON_OR_NULL, /* returns a pointer to a sock_common or NULL */
> + RET_PTR_TO_NF_CONN_OR_NULL, /* returns a pointer to a nf_conn or NULL */
> };
>
> /* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
> @@ -316,6 +318,8 @@ enum bpf_reg_type {
> PTR_TO_TP_BUFFER, /* reg points to a writable raw tp's buffer */
> PTR_TO_XDP_SOCK, /* reg points to struct xdp_sock */
> PTR_TO_BTF_ID, /* reg points to kernel struct */
> + PTR_TO_NF_CONN, /* reg points to struct nf_conn */
> + PTR_TO_NF_CONN_OR_NULL, /* reg points to struct nf_conn or NULL */
> };
>
> /* The information passed from prog-specific *_is_valid_access
> @@ -1513,4 +1517,29 @@ enum bpf_text_poke_type {
> int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
> void *addr1, void *addr2);
>
> +#if IS_ENABLED(CONFIG_NF_CONNTRACK)
> +bool bpf_nf_conn_is_valid_access(int off, int size, enum bpf_access_type type,
> + struct bpf_insn_access_aux *info);
> +
> +u32 bpf_nf_conn_convert_ctx_access(enum bpf_access_type type,
> + const struct bpf_insn *si,
> + struct bpf_insn *insn_buf,
> + struct bpf_prog *prog, u32 *target_size);
> +#else
> +static inline bool bpf_nf_conn_is_valid_access(int off, int size,
> + enum bpf_access_type type,
> + struct bpf_insn_access_aux *info)
> +{
> + return false;
> +}
> +
> +static inline u32 bpf_nf_conn_convert_ctx_access(enum bpf_access_type type,
> + const struct bpf_insn *si,
> + struct bpf_insn *insn_buf,
> + struct bpf_prog *prog, u32 *target_size)
> +{
> + return 0;
> +}
> +#endif /* CONFIG_NF_CONNTRACK */
> +
> #endif /* _LINUX_BPF_H */
> diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
> index eb312e7..a360ced 100644
> --- a/include/linux/netfilter.h
> +++ b/include/linux/netfilter.h
> @@ -451,6 +451,9 @@ static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
> struct nf_conntrack_tuple;
> bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
> const struct sk_buff *skb);
> +struct nf_conntrack_tuple_hash *
> +nf_ct_find_get(struct net *net, const struct nf_conntrack_zone *zone,
> + const struct nf_conntrack_tuple *tuple);
> #else
> static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
> struct nf_conntrack_tuple;
> @@ -459,6 +462,12 @@ static inline bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
> {
> return false;
> }
> +static inline struct nf_conntrack_tuple_hash *
> +nf_ct_find_get(struct net *net, const struct nf_conntrack_zone *zone,
> + const struct nf_conntrack_tuple *tuple)
> +{
> + return NULL;
> +}
> #endif
>
> struct nf_conn;
> @@ -469,6 +478,9 @@ struct nf_ct_hook {
> void (*destroy)(struct nf_conntrack *);
> bool (*get_tuple_skb)(struct nf_conntrack_tuple *,
> const struct sk_buff *);
> + struct nf_conntrack_tuple_hash *
> + (*find_get)(struct net *net, const struct nf_conntrack_zone *zone,
> + const struct nf_conntrack_tuple *tuple);
> };
> extern struct nf_ct_hook __rcu *nf_ct_hook;
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 033d90a..85c4b3f 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -2885,6 +2885,88 @@ struct bpf_stack_build_id {
> * **-EPERM** if no permission to send the *sig*.
> *
> * **-EAGAIN** if bpf program can try again.
> + *
> + * struct bpf_nf_conn *bpf_ct_lookup_tcp(void *ctx, struct bpf_nf_conntrack_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
> + * Description
> + * Look for TCP nf_conntrack entry matching *tuple*, optionally in
> + * a child network namespace *netns*. The return value must be
> + * checked, and if non-**NULL**, released via
> + * **bpf_ct_release**\ ().
> + *
> + * The *ctx* should point to the context of the program, such as
> + * the skb or xdp_md (depending on the hook in use). This is used
> + * to determine the base network namespace for the lookup.
> + *
> + * *tuple_size* must be one of:
> + *
> + * **sizeof**\ (*tuple*\ **->ipv4**)
> + * Look for an IPv4 nf_conn.
> + * **sizeof**\ (*tuple*\ **->ipv6**)
> + * Look for an IPv6 nf_conn.
> + *
> + * If the *netns* is a negative signed 32-bit integer, then the
> + * nf_conn lookup table in the netns associated with the *ctx* will
> + * will be used. For the TC hooks, this is the netns of the device
> + * in the skb. For XDP hooks, this is the netns of the device in
> + * the xdp_md. If *netns* is any other signed 32-bit value greater
> + * than or equal to zero then it specifies the ID of the netns
> + * relative to the netns associated with the *ctx*. *netns* values
> + * beyond the range of 32-bit integers are reserved for future
> + * use.
> + *
> + * All values for *flags* are reserved for future usage, and must
> + * be left at zero.
> + *
> + * This helper will always return NULL if the kernel was compiled
> + * without **CONFIG_NF_CONNTRACK**.
> + * Return
> + * Pointer to **struct bpf_nf_conn**, or **NULL** in case of
> + * failure.
> + *
> + * struct bpf_nf_conn *bpf_ct_lookup_udp(void *ctx, struct bpf_nf_conntrack_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
> + * Description
> + * Look for UDP nf_conntrack entry matching *tuple*, optionally in
> + * a child network namespace *netns*. The return value must be
> + * checked, and if non-**NULL**, released via
> + * **bpf_ct_release**\ ().
> + *
> + * The *ctx* should point to the context of the program, such as
> + * the skb or xdp_md (depending on the hook in use). This is used
> + * to determine the base network namespace for the lookup.
> + *
> + * *tuple_size* must be one of:
> + *
> + * **sizeof**\ (*tuple*\ **->ipv4**)
> + * Look for an IPv4 nf_conn.
> + * **sizeof**\ (*tuple*\ **->ipv6**)
> + * Look for an IPv6 nf_conn.
> + *
> + * If the *netns* is a negative signed 32-bit integer, then the
> + * nf_conn lookup table in the netns associated with the *ctx* will
> + * will be used. For the TC hooks, this is the netns of the device
> + * in the skb. For XDP hooks, this is the netns of the device in
> + * the xdp_md. If *netns* is any other signed 32-bit value greater
> + * than or equal to zero then it specifies the ID of the netns
> + * relative to the netns associated with the *ctx*. *netns* values
> + * beyond the range of 32-bit integers are reserved for future
> + * use.
> + *
> + * All values for *flags* are reserved for future usage, and must
> + * be left at zero.
> + *
> + * This helper will always return NULL if the kernel was compiled
> + * without **CONFIG_NF_CONNTRACK**.
> + * Return
> + * Pointer to **struct bpf_nf_conn**, or **NULL** in case of
> + * failure.
> + *
> + * int bpf_ct_release(struct bpf_nf_conn *ct)
> + * Description
> + * Release the reference held by *ct*. *ct* must be a
> + * non-**NULL** pointer that was returned from
> + * **bpf_ct_lookup_xxx**\ ().
> + * Return
> + * 0 on success, or a negative error in case of failure.
> */
> #define __BPF_FUNC_MAPPER(FN) \
> FN(unspec), \
> @@ -3004,7 +3086,10 @@ struct bpf_stack_build_id {
> FN(probe_read_user_str), \
> FN(probe_read_kernel_str), \
> FN(tcp_send_ack), \
> - FN(send_signal_thread),
> + FN(send_signal_thread), \
> + FN(ct_lookup_tcp), \
> + FN(ct_lookup_udp), \
> + FN(ct_release),
>
> /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> * function eBPF program intends to call
> @@ -3278,6 +3363,30 @@ struct bpf_sock_tuple {
> };
> };
>
> +struct bpf_nf_conn {
> + __u32 cpu;
> + __u32 mark;
> + __u32 status;
> + __u32 timeout;
> +};
> +
> +struct bpf_nf_conntrack_tuple {
> + union {
> + struct {
> + __be32 saddr;
> + __be32 daddr;
> + __be16 sport;
> + __be16 dport;
> + } ipv4;
> + struct {
> + __be32 saddr[4];
> + __be32 daddr[4];
> + __be16 sport;
> + __be16 dport;
> + } ipv6;
> + };
> +};
> +
> struct bpf_xdp_sock {
> __u32 queue_id;
> };
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index ca17dccc..0ea0ee7 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -362,6 +362,11 @@ static const char *ltrim(const char *s)
> env->prev_linfo = linfo;
> }
>
> +static bool type_is_nf_ct_pointer(enum bpf_reg_type type)
> +{
> + return type == PTR_TO_NF_CONN;
> +}
> +
> static bool type_is_pkt_pointer(enum bpf_reg_type type)
> {
> return type == PTR_TO_PACKET ||
> @@ -381,7 +386,8 @@ static bool reg_type_may_be_null(enum bpf_reg_type type)
> return type == PTR_TO_MAP_VALUE_OR_NULL ||
> type == PTR_TO_SOCKET_OR_NULL ||
> type == PTR_TO_SOCK_COMMON_OR_NULL ||
> - type == PTR_TO_TCP_SOCK_OR_NULL;
> + type == PTR_TO_TCP_SOCK_OR_NULL ||
> + type == PTR_TO_NF_CONN_OR_NULL;
> }
>
> static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg)
> @@ -395,12 +401,15 @@ static bool reg_type_may_be_refcounted_or_null(enum bpf_reg_type type)
> return type == PTR_TO_SOCKET ||
> type == PTR_TO_SOCKET_OR_NULL ||
> type == PTR_TO_TCP_SOCK ||
> - type == PTR_TO_TCP_SOCK_OR_NULL;
> + type == PTR_TO_TCP_SOCK_OR_NULL ||
> + type == PTR_TO_NF_CONN ||
> + type == PTR_TO_NF_CONN_OR_NULL;
> }
>
> static bool arg_type_may_be_refcounted(enum bpf_arg_type type)
> {
> - return type == ARG_PTR_TO_SOCK_COMMON;
> + return type == ARG_PTR_TO_SOCK_COMMON ||
> + type == ARG_PTR_TO_NF_CONN;
> }
>
> /* Determine whether the function releases some resources allocated by another
> @@ -409,14 +418,17 @@ static bool arg_type_may_be_refcounted(enum bpf_arg_type type)
> */
> static bool is_release_function(enum bpf_func_id func_id)
> {
> - return func_id == BPF_FUNC_sk_release;
> + return func_id == BPF_FUNC_sk_release ||
> + func_id == BPF_FUNC_ct_release;
> }
>
> static bool is_acquire_function(enum bpf_func_id func_id)
> {
> return func_id == BPF_FUNC_sk_lookup_tcp ||
> func_id == BPF_FUNC_sk_lookup_udp ||
> - func_id == BPF_FUNC_skc_lookup_tcp;
> + func_id == BPF_FUNC_skc_lookup_tcp ||
> + func_id == BPF_FUNC_ct_lookup_tcp ||
> + func_id == BPF_FUNC_ct_lookup_udp;
> }
>
> static bool is_ptr_cast_function(enum bpf_func_id func_id)
> @@ -447,6 +459,8 @@ static bool is_ptr_cast_function(enum bpf_func_id func_id)
> [PTR_TO_TP_BUFFER] = "tp_buffer",
> [PTR_TO_XDP_SOCK] = "xdp_sock",
> [PTR_TO_BTF_ID] = "ptr_",
> + [PTR_TO_NF_CONN] = "nf_conn",
> + [PTR_TO_NF_CONN_OR_NULL] = "nf_conn_or_null",
> };
>
> static char slot_type_char[] = {
> @@ -1913,6 +1927,8 @@ static bool is_spillable_regtype(enum bpf_reg_type type)
> case PTR_TO_TCP_SOCK_OR_NULL:
> case PTR_TO_XDP_SOCK:
> case PTR_TO_BTF_ID:
> + case PTR_TO_NF_CONN:
> + case PTR_TO_NF_CONN_OR_NULL:
> return true;
> default:
> return false;
> @@ -2440,6 +2456,35 @@ static int check_flow_keys_access(struct bpf_verifier_env *env, int off,
> return 0;
> }
>
> +static int check_nf_ct_access(struct bpf_verifier_env *env, int insn_idx,
> + u32 regno, int off, int size,
> + enum bpf_access_type t)
> +{
> + struct bpf_reg_state *regs = cur_regs(env);
> + struct bpf_reg_state *reg = ®s[regno];
> + struct bpf_insn_access_aux info = {};
> + bool valid;
> +
> + switch (reg->type) {
> + case PTR_TO_NF_CONN:
> + valid = bpf_nf_conn_is_valid_access(off, size, t, &info);
> + break;
> + default:
> + valid = false;
> + }
> +
> + if (valid) {
> + env->insn_aux_data[insn_idx].ctx_field_size =
> + info.ctx_field_size;
> + return 0;
> + }
> +
> + verbose(env, "R%d invalid %s access off=%d size=%d\n",
> + regno, reg_type_str[reg->type], off, size);
> +
> + return -EACCES;
> +}
> +
> static int check_sock_access(struct bpf_verifier_env *env, int insn_idx,
> u32 regno, int off, int size,
> enum bpf_access_type t)
> @@ -2511,6 +2556,13 @@ static bool is_ctx_reg(struct bpf_verifier_env *env, int regno)
> return reg->type == PTR_TO_CTX;
> }
>
> +static bool is_nf_ct_reg(struct bpf_verifier_env *env, int regno)
> +{
> + const struct bpf_reg_state *reg = reg_state(env, regno);
> +
> + return type_is_nf_ct_pointer(reg->type);
> +}
> +
> static bool is_sk_reg(struct bpf_verifier_env *env, int regno)
> {
> const struct bpf_reg_state *reg = reg_state(env, regno);
> @@ -2635,6 +2687,9 @@ static int check_ptr_alignment(struct bpf_verifier_env *env,
> case PTR_TO_XDP_SOCK:
> pointer_desc = "xdp_sock ";
> break;
> + case PTR_TO_NF_CONN:
> + pointer_desc = "nf_conn ";
> + break;
> default:
> break;
> }
> @@ -3050,6 +3105,15 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
> err = check_sock_access(env, insn_idx, regno, off, size, t);
> if (!err && value_regno >= 0)
> mark_reg_unknown(env, regs, value_regno);
> + } else if (type_is_nf_ct_pointer(reg->type)) {
> + if (t == BPF_WRITE) {
> + verbose(env, "R%d cannot write into %s\n",
> + regno, reg_type_str[reg->type]);
> + return -EACCES;
> + }
> + err = check_nf_ct_access(env, insn_idx, regno, off, size, t);
> + if (!err && value_regno >= 0)
> + mark_reg_unknown(env, regs, value_regno);
> } else if (reg->type == PTR_TO_TP_BUFFER) {
> err = check_tp_buffer_access(env, reg, regno, off, size);
> if (!err && t == BPF_READ && value_regno >= 0)
> @@ -3099,7 +3163,8 @@ static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_ins
> if (is_ctx_reg(env, insn->dst_reg) ||
> is_pkt_reg(env, insn->dst_reg) ||
> is_flow_key_reg(env, insn->dst_reg) ||
> - is_sk_reg(env, insn->dst_reg)) {
> + is_sk_reg(env, insn->dst_reg) ||
> + is_nf_ct_reg(env, insn->dst_reg)) {
> verbose(env, "BPF_XADD stores into R%d %s is not allowed\n",
> insn->dst_reg,
> reg_type_str[reg_state(env, insn->dst_reg)->type]);
> @@ -3501,6 +3566,19 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
> regno);
> return -EACCES;
> }
> + } else if (arg_type == ARG_PTR_TO_NF_CONN) {
> + expected_type = PTR_TO_NF_CONN;
> + if (!type_is_nf_ct_pointer(type))
> + goto err_type;
> + if (reg->ref_obj_id) {
> + if (meta->ref_obj_id) {
> + verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n",
> + regno, reg->ref_obj_id,
> + meta->ref_obj_id);
> + return -EFAULT;
> + }
> + meta->ref_obj_id = reg->ref_obj_id;
> + }
> } else if (arg_type == ARG_PTR_TO_SPIN_LOCK) {
> if (meta->func_id == BPF_FUNC_spin_lock) {
> if (process_spin_lock(env, regno, true))
> @@ -4368,6 +4446,10 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
> mark_reg_known_zero(env, regs, BPF_REG_0);
> regs[BPF_REG_0].type = PTR_TO_TCP_SOCK_OR_NULL;
> regs[BPF_REG_0].id = ++env->id_gen;
> + } else if (fn->ret_type == RET_PTR_TO_NF_CONN_OR_NULL) {
> + mark_reg_known_zero(env, regs, BPF_REG_0);
> + regs[BPF_REG_0].type = PTR_TO_NF_CONN_OR_NULL;
> + regs[BPF_REG_0].id = ++env->id_gen;
> } else {
> verbose(env, "unknown return type %d of func %s#%d\n",
> fn->ret_type, func_id_name(func_id), func_id);
> @@ -4649,6 +4731,8 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
> case PTR_TO_TCP_SOCK:
> case PTR_TO_TCP_SOCK_OR_NULL:
> case PTR_TO_XDP_SOCK:
> + case PTR_TO_NF_CONN:
> + case PTR_TO_NF_CONN_OR_NULL:
> verbose(env, "R%d pointer arithmetic on %s prohibited\n",
> dst, reg_type_str[ptr_reg->type]);
> return -EACCES;
> @@ -5915,6 +5999,8 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state,
> reg->type = PTR_TO_SOCK_COMMON;
> } else if (reg->type == PTR_TO_TCP_SOCK_OR_NULL) {
> reg->type = PTR_TO_TCP_SOCK;
> + } else if (reg->type == PTR_TO_NF_CONN_OR_NULL) {
> + reg->type = PTR_TO_NF_CONN;
> }
> if (is_null) {
> /* We don't need id and ref_obj_id from this point
> @@ -7232,6 +7318,8 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
> case PTR_TO_TCP_SOCK:
> case PTR_TO_TCP_SOCK_OR_NULL:
> case PTR_TO_XDP_SOCK:
> + case PTR_TO_NF_CONN:
> + case PTR_TO_NF_CONN_OR_NULL:
> /* Only valid matches are exact, which memcmp() above
> * would have accepted
> */
> @@ -7760,6 +7848,8 @@ static bool reg_type_mismatch_ok(enum bpf_reg_type type)
> case PTR_TO_TCP_SOCK_OR_NULL:
> case PTR_TO_XDP_SOCK:
> case PTR_TO_BTF_ID:
> + case PTR_TO_NF_CONN:
> + case PTR_TO_NF_CONN_OR_NULL:
> return false;
> default:
> return true;
> @@ -8867,6 +8957,9 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
> return -EINVAL;
> }
> continue;
> + case PTR_TO_NF_CONN:
> + convert_ctx_access = bpf_nf_conn_convert_ctx_access;
> + break;
> default:
> continue;
> }
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 17de674..80319d3 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -74,6 +74,12 @@
> #include <net/ipv6_stubs.h>
> #include <net/bpf_sk_storage.h>
>
> +#if IS_ENABLED(CONFIG_NF_CONNTRACK)
> +#include <net/netfilter/nf_conntrack_tuple.h>
> +#include <net/netfilter/nf_conntrack_core.h>
> +#include <net/netfilter/nf_conntrack.h>
> +#endif
> +
> /**
> * sk_filter_trim_cap - run a packet through a socket filter
> * @sk: sock associated with &sk_buff
> @@ -5122,6 +5128,253 @@ static void bpf_update_srh_state(struct sk_buff *skb)
> };
> #endif /* CONFIG_IPV6_SEG6_BPF */
>
> +#if IS_ENABLED(CONFIG_NF_CONNTRACK)
> +bool bpf_nf_conn_is_valid_access(int off, int size, enum bpf_access_type type,
> + struct bpf_insn_access_aux *info)
> +{
> + if (off < 0 || off >= offsetofend(struct bpf_nf_conn,
> + timeout))
> + return false;
> +
> + if (off % size != 0)
> + return false;
> +
> + return size == sizeof(__u32);
> +}
> +
> +u32 bpf_nf_conn_convert_ctx_access(enum bpf_access_type type,
> + const struct bpf_insn *si,
> + struct bpf_insn *insn_buf,
> + struct bpf_prog *prog, u32 *target_size)
> +{
> + struct bpf_insn *insn = insn_buf;
> +
> + switch (si->off) {
> + case offsetof(struct bpf_nf_conn, cpu):
> + BUILD_BUG_ON(FIELD_SIZEOF(struct nf_conn, cpu) != 2);
> +
> + *insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->src_reg,
> + offsetof(struct nf_conn, cpu));
> +
> + break;
> +
> + case offsetof(struct bpf_nf_conn, mark):
> +#if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK)
> + BUILD_BUG_ON(FIELD_SIZEOF(struct nf_conn, mark) != 4);
> +
> + *insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->src_reg,
> + offsetof(struct nf_conn, mark));
> +#else
> + *target_size = 4;
> + *insn++ = BPF_MOV64_IMM(si->dst_reg, 0);
> +#endif
> + break;
> +
> + case offsetof(struct bpf_nf_conn, status):
> + BUILD_BUG_ON(FIELD_SIZEOF(struct nf_conn, status) < 4 ||
> + __IPS_MAX_BIT > 32);
> +
> + *insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->src_reg,
> + offsetof(struct nf_conn, status));
> +
> + break;
> +
> + case offsetof(struct bpf_nf_conn, timeout):
> + BUILD_BUG_ON(FIELD_SIZEOF(struct nf_conn, timeout) != 4);
> +
> + *insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->src_reg,
> + offsetof(struct nf_conn, timeout));
> +
> + break;
> + }
> +
> + return insn - insn_buf;
> +}
> +
> +static struct nf_conn *
> +ct_lookup(struct net *net, struct bpf_nf_conntrack_tuple *tuple,
> + u8 family, u8 proto)
> +{
> + struct nf_conntrack_tuple_hash *hash;
> + struct nf_conntrack_tuple tup;
> + struct nf_conn *ct = NULL;
> +
> + memset(&tup, 0, sizeof(tup));
> +
> + tup.dst.protonum = proto;
> + tup.src.l3num = family;
> +
> + if (family == AF_INET) {
> + tup.src.u3.ip = tuple->ipv4.saddr;
> + tup.dst.u3.ip = tuple->ipv4.daddr;
> + tup.src.u.tcp.port = tuple->ipv4.sport;
> + tup.dst.u.tcp.port = tuple->ipv4.dport;
> +#if IS_ENABLED(CONFIG_IPV6)
> + } else {
> + memcpy(tup.src.u3.ip6, tuple->ipv6.saddr, sizeof(tup.src.u3.ip6));
> + memcpy(tup.dst.u3.ip6, tuple->ipv6.daddr, sizeof(tup.dst.u3.ip6));
> + tup.src.u.tcp.port = tuple->ipv6.sport;
> + tup.dst.u.tcp.port = tuple->ipv6.dport;
> +#endif
> + }
> +
> + hash = nf_ct_find_get(net, &nf_ct_zone_dflt, &tup);
> + if (!hash)
> + goto out;
> + ct = nf_ct_tuplehash_to_ctrack(hash);
> +
> +out:
> + return ct;
> +}
> +
> +static struct nf_conn *
> +__bpf_ct_lookup(struct sk_buff *skb, struct bpf_nf_conntrack_tuple *tuple, u32 len,
> + struct net *caller_net, u8 proto, u64 netns_id, u64 flags)
> +{
> + struct nf_conn *ct = NULL;
> + u8 family = AF_UNSPEC;
> + struct net *net;
> +
> + if (len == sizeof(tuple->ipv4))
> + family = AF_INET;
> + else if (len == sizeof(tuple->ipv6))
> + family = AF_INET6;
> + else
> + goto out;
> +
> + if (unlikely(family == AF_UNSPEC || flags ||
> + !((s32)netns_id < 0 || netns_id <= S32_MAX)))
> + goto out;
> +
> + if ((s32)netns_id < 0) {
> + net = caller_net;
> + ct = ct_lookup(net, tuple, family, proto);
> + } else {
> + net = get_net_ns_by_id(caller_net, netns_id);
> + if (unlikely(!net))
> + goto out;
> + ct = ct_lookup(net, tuple, family, proto);
> + put_net(net);
> + }
> +
> +out:
> + return ct;
> +}
> +
> +static struct nf_conn *
> +bpf_ct_lookup(struct sk_buff *skb, struct bpf_nf_conntrack_tuple *tuple, u32 len,
> + u8 proto, u64 netns_id, u64 flags)
> +{
> + struct net *caller_net;
> +
> + if (skb->dev) {
> + caller_net = dev_net(skb->dev);
> + } else {
> + caller_net = sock_net(skb->sk);
> + }
> +
> + return __bpf_ct_lookup(skb, tuple, len, caller_net, proto,
> + netns_id, flags);
> +}
> +
> +BPF_CALL_5(bpf_ct_lookup_tcp, struct sk_buff *, skb,
> + struct bpf_nf_conntrack_tuple *, tuple, u32, len, u64, netns_id,
> + u64, flags)
> +{
> + return (unsigned long)bpf_ct_lookup(skb, tuple, len, IPPROTO_TCP,
> + netns_id, flags);
> +}
> +
> +static const struct bpf_func_proto bpf_ct_lookup_tcp_proto = {
> + .func = bpf_ct_lookup_tcp,
> + .gpl_only = true,
> + .pkt_access = true,
> + .ret_type = RET_PTR_TO_NF_CONN_OR_NULL,
> + .arg1_type = ARG_PTR_TO_CTX,
> + .arg2_type = ARG_PTR_TO_MEM,
> + .arg3_type = ARG_CONST_SIZE,
> + .arg4_type = ARG_ANYTHING,
> + .arg5_type = ARG_ANYTHING,
> +};
> +
> +BPF_CALL_5(bpf_xdp_ct_lookup_tcp, struct xdp_buff *, ctx,
> + struct bpf_nf_conntrack_tuple *, tuple, u32, len, u32, netns_id,
> + u64, flags)
> +{
> + struct net *caller_net = dev_net(ctx->rxq->dev);
> +
> + return (unsigned long)__bpf_ct_lookup(NULL, tuple, len, caller_net,
> + IPPROTO_TCP, netns_id, flags);
> +}
> +
> +static const struct bpf_func_proto bpf_xdp_ct_lookup_tcp_proto = {
> + .func = bpf_xdp_ct_lookup_tcp,
> + .gpl_only = true,
> + .pkt_access = true,
> + .ret_type = RET_PTR_TO_NF_CONN_OR_NULL,
> + .arg1_type = ARG_PTR_TO_CTX,
> + .arg2_type = ARG_PTR_TO_MEM,
> + .arg3_type = ARG_CONST_SIZE,
> + .arg4_type = ARG_ANYTHING,
> + .arg5_type = ARG_ANYTHING,
> +};
> +
> +BPF_CALL_5(bpf_ct_lookup_udp, struct sk_buff *, skb,
> + struct bpf_nf_conntrack_tuple *, tuple, u32, len, u64, netns_id,
> + u64, flags)
> +{
> + return (unsigned long)bpf_ct_lookup(skb, tuple, len, IPPROTO_UDP,
> + netns_id, flags);
> +}
> +
> +static const struct bpf_func_proto bpf_ct_lookup_udp_proto = {
> + .func = bpf_ct_lookup_udp,
> + .gpl_only = true,
> + .pkt_access = true,
> + .ret_type = RET_PTR_TO_NF_CONN_OR_NULL,
> + .arg1_type = ARG_PTR_TO_CTX,
> + .arg2_type = ARG_PTR_TO_MEM,
> + .arg3_type = ARG_CONST_SIZE,
> + .arg4_type = ARG_ANYTHING,
> + .arg5_type = ARG_ANYTHING,
> +};
> +
> +BPF_CALL_5(bpf_xdp_ct_lookup_udp, struct xdp_buff *, ctx,
> + struct bpf_nf_conntrack_tuple *, tuple, u32, len, u32, netns_id,
> + u64, flags)
> +{
> + struct net *caller_net = dev_net(ctx->rxq->dev);
> +
> + return (unsigned long)__bpf_ct_lookup(NULL, tuple, len, caller_net,
> + IPPROTO_UDP, netns_id, flags);
> +}
> +
> +static const struct bpf_func_proto bpf_xdp_ct_lookup_udp_proto = {
> + .func = bpf_xdp_ct_lookup_udp,
> + .gpl_only = true,
> + .pkt_access = true,
> + .ret_type = RET_PTR_TO_NF_CONN_OR_NULL,
> + .arg1_type = ARG_PTR_TO_CTX,
> + .arg2_type = ARG_PTR_TO_MEM,
> + .arg3_type = ARG_CONST_SIZE,
> + .arg4_type = ARG_ANYTHING,
> + .arg5_type = ARG_ANYTHING,
> +};
> +
> +BPF_CALL_1(bpf_ct_release, struct nf_conn *, ct)
> +{
> + nf_conntrack_put(&ct->ct_general);
> + return 0;
> +}
> +
> +static const struct bpf_func_proto bpf_ct_release_proto = {
> + .func = bpf_ct_release,
> + .gpl_only = true,
> + .ret_type = RET_INTEGER,
> + .arg1_type = ARG_PTR_TO_NF_CONN,
> +};
> +#endif
> +
> #ifdef CONFIG_INET
> static struct sock *sk_lookup(struct net *net, struct bpf_sock_tuple *tuple,
> int dif, int sdif, u8 family, u8 proto)
> @@ -6139,6 +6392,14 @@ bool bpf_helper_changes_pkt_data(void *func)
> case BPF_FUNC_tcp_gen_syncookie:
> return &bpf_tcp_gen_syncookie_proto;
> #endif
> +#if IS_ENABLED(CONFIG_NF_CONNTRACK)
> + case BPF_FUNC_ct_lookup_tcp:
> + return &bpf_ct_lookup_tcp_proto;
> + case BPF_FUNC_ct_lookup_udp:
> + return &bpf_ct_lookup_udp_proto;
> + case BPF_FUNC_ct_release:
> + return &bpf_ct_release_proto;
> +#endif
> default:
> return bpf_base_func_proto(func_id);
> }
> @@ -6180,6 +6441,14 @@ bool bpf_helper_changes_pkt_data(void *func)
> case BPF_FUNC_tcp_gen_syncookie:
> return &bpf_tcp_gen_syncookie_proto;
> #endif
> +#if IS_ENABLED(CONFIG_NF_CONNTRACK)
> + case BPF_FUNC_ct_lookup_tcp:
> + return &bpf_xdp_ct_lookup_tcp_proto;
> + case BPF_FUNC_ct_lookup_udp:
> + return &bpf_xdp_ct_lookup_udp_proto;
> + case BPF_FUNC_ct_release:
> + return &bpf_ct_release_proto;
> +#endif
> default:
> return bpf_base_func_proto(func_id);
> }
> @@ -6284,6 +6553,14 @@ bool bpf_helper_changes_pkt_data(void *func)
> case BPF_FUNC_skc_lookup_tcp:
> return &bpf_skc_lookup_tcp_proto;
> #endif
> +#if IS_ENABLED(CONFIG_NF_CONNTRACK)
> + case BPF_FUNC_ct_lookup_tcp:
> + return &bpf_ct_lookup_tcp_proto;
> + case BPF_FUNC_ct_lookup_udp:
> + return &bpf_ct_lookup_udp_proto;
> + case BPF_FUNC_ct_release:
> + return &bpf_ct_release_proto;
> +#endif
> default:
> return bpf_base_func_proto(func_id);
> }
> diff --git a/net/netfilter/core.c b/net/netfilter/core.c
> index 78f046e..855c6b0 100644
> --- a/net/netfilter/core.c
> +++ b/net/netfilter/core.c
> @@ -617,6 +617,22 @@ bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
> }
> EXPORT_SYMBOL(nf_ct_get_tuple_skb);
>
> +struct nf_conntrack_tuple_hash *
> +nf_ct_find_get(struct net *net, const struct nf_conntrack_zone *zone,
> + const struct nf_conntrack_tuple *tuple)
> +{
> + struct nf_ct_hook *ct_hook;
> + struct nf_conntrack_tuple_hash *ret = NULL;
> +
> + rcu_read_lock();
> + ct_hook = rcu_dereference(nf_ct_hook);
> + if (ct_hook)
> + ret = ct_hook->find_get(net, zone, tuple);
> + rcu_read_unlock();
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(nf_ct_find_get);
> +
> /* Built-in default zone used e.g. by modules. */
> const struct nf_conntrack_zone nf_ct_zone_dflt = {
> .id = NF_CT_DEFAULT_ZONE_ID,
> diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
> index f4c4b46..a44df88 100644
> --- a/net/netfilter/nf_conntrack_core.c
> +++ b/net/netfilter/nf_conntrack_core.c
> @@ -2484,6 +2484,7 @@ int nf_conntrack_init_start(void)
> .update = nf_conntrack_update,
> .destroy = destroy_conntrack,
> .get_tuple_skb = nf_conntrack_get_tuple_skb,
> + .find_get = nf_conntrack_find_get,
> };
>
> void nf_conntrack_init_end(void)
> diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py
> index 90baf7d..26f0c2a 100755
> --- a/scripts/bpf_helpers_doc.py
> +++ b/scripts/bpf_helpers_doc.py
> @@ -398,6 +398,8 @@ class PrinterHelpers(Printer):
>
> type_fwds = [
> 'struct bpf_fib_lookup',
> + 'struct bpf_nf_conn',
> + 'struct bpf_nf_conntrack_tuple',
> 'struct bpf_perf_event_data',
> 'struct bpf_perf_event_value',
> 'struct bpf_sock',
> @@ -433,6 +435,8 @@ class PrinterHelpers(Printer):
> '__wsum',
>
> 'struct bpf_fib_lookup',
> + 'struct bpf_nf_conn',
> + 'struct bpf_nf_conntrack_tuple',
> 'struct bpf_perf_event_data',
> 'struct bpf_perf_event_value',
> 'struct bpf_sock',
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 033d90a..85c4b3f 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -2885,6 +2885,88 @@ struct bpf_stack_build_id {
> * **-EPERM** if no permission to send the *sig*.
> *
> * **-EAGAIN** if bpf program can try again.
> + *
> + * struct bpf_nf_conn *bpf_ct_lookup_tcp(void *ctx, struct bpf_nf_conntrack_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
> + * Description
> + * Look for TCP nf_conntrack entry matching *tuple*, optionally in
> + * a child network namespace *netns*. The return value must be
> + * checked, and if non-**NULL**, released via
> + * **bpf_ct_release**\ ().
> + *
> + * The *ctx* should point to the context of the program, such as
> + * the skb or xdp_md (depending on the hook in use). This is used
> + * to determine the base network namespace for the lookup.
> + *
> + * *tuple_size* must be one of:
> + *
> + * **sizeof**\ (*tuple*\ **->ipv4**)
> + * Look for an IPv4 nf_conn.
> + * **sizeof**\ (*tuple*\ **->ipv6**)
> + * Look for an IPv6 nf_conn.
> + *
> + * If the *netns* is a negative signed 32-bit integer, then the
> + * nf_conn lookup table in the netns associated with the *ctx* will
> + * will be used. For the TC hooks, this is the netns of the device
> + * in the skb. For XDP hooks, this is the netns of the device in
> + * the xdp_md. If *netns* is any other signed 32-bit value greater
> + * than or equal to zero then it specifies the ID of the netns
> + * relative to the netns associated with the *ctx*. *netns* values
> + * beyond the range of 32-bit integers are reserved for future
> + * use.
> + *
> + * All values for *flags* are reserved for future usage, and must
> + * be left at zero.
> + *
> + * This helper will always return NULL if the kernel was compiled
> + * without **CONFIG_NF_CONNTRACK**.
> + * Return
> + * Pointer to **struct bpf_nf_conn**, or **NULL** in case of
> + * failure.
> + *
> + * struct bpf_nf_conn *bpf_ct_lookup_udp(void *ctx, struct bpf_nf_conntrack_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
> + * Description
> + * Look for UDP nf_conntrack entry matching *tuple*, optionally in
> + * a child network namespace *netns*. The return value must be
> + * checked, and if non-**NULL**, released via
> + * **bpf_ct_release**\ ().
> + *
> + * The *ctx* should point to the context of the program, such as
> + * the skb or xdp_md (depending on the hook in use). This is used
> + * to determine the base network namespace for the lookup.
> + *
> + * *tuple_size* must be one of:
> + *
> + * **sizeof**\ (*tuple*\ **->ipv4**)
> + * Look for an IPv4 nf_conn.
> + * **sizeof**\ (*tuple*\ **->ipv6**)
> + * Look for an IPv6 nf_conn.
> + *
> + * If the *netns* is a negative signed 32-bit integer, then the
> + * nf_conn lookup table in the netns associated with the *ctx* will
> + * will be used. For the TC hooks, this is the netns of the device
> + * in the skb. For XDP hooks, this is the netns of the device in
> + * the xdp_md. If *netns* is any other signed 32-bit value greater
> + * than or equal to zero then it specifies the ID of the netns
> + * relative to the netns associated with the *ctx*. *netns* values
> + * beyond the range of 32-bit integers are reserved for future
> + * use.
> + *
> + * All values for *flags* are reserved for future usage, and must
> + * be left at zero.
> + *
> + * This helper will always return NULL if the kernel was compiled
> + * without **CONFIG_NF_CONNTRACK**.
> + * Return
> + * Pointer to **struct bpf_nf_conn**, or **NULL** in case of
> + * failure.
> + *
> + * int bpf_ct_release(struct bpf_nf_conn *ct)
> + * Description
> + * Release the reference held by *ct*. *ct* must be a
> + * non-**NULL** pointer that was returned from
> + * **bpf_ct_lookup_xxx**\ ().
> + * Return
> + * 0 on success, or a negative error in case of failure.
> */
> #define __BPF_FUNC_MAPPER(FN) \
> FN(unspec), \
> @@ -3004,7 +3086,10 @@ struct bpf_stack_build_id {
> FN(probe_read_user_str), \
> FN(probe_read_kernel_str), \
> FN(tcp_send_ack), \
> - FN(send_signal_thread),
> + FN(send_signal_thread), \
> + FN(ct_lookup_tcp), \
> + FN(ct_lookup_udp), \
> + FN(ct_release),
>
> /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> * function eBPF program intends to call
> @@ -3278,6 +3363,30 @@ struct bpf_sock_tuple {
> };
> };
>
> +struct bpf_nf_conn {
> + __u32 cpu;
> + __u32 mark;
> + __u32 status;
> + __u32 timeout;
> +};
> +
> +struct bpf_nf_conntrack_tuple {
> + union {
> + struct {
> + __be32 saddr;
> + __be32 daddr;
> + __be16 sport;
> + __be16 dport;
> + } ipv4;
> + struct {
> + __be32 saddr[4];
> + __be32 daddr[4];
> + __be16 sport;
> + __be16 dport;
> + } ipv6;
> + };
> +};
> +
> struct bpf_xdp_sock {
> __u32 queue_id;
> };
> --
> 1.8.3.1
>
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