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-rw-r--r--include/linux/bpf.h4
-rw-r--r--include/linux/skbuff.h14
-rw-r--r--include/uapi/linux/bpf.h21
-rw-r--r--kernel/bpf/helpers.c3
-rw-r--r--kernel/bpf/verifier.c54
-rw-r--r--net/core/filter.c134
6 files changed, 196 insertions, 34 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 9a904f63f8c1..5691fdc83819 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -96,6 +96,7 @@ enum bpf_return_type {
struct bpf_func_proto {
u64 (*func)(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
bool gpl_only;
+ bool pkt_access;
enum bpf_return_type ret_type;
enum bpf_arg_type arg1_type;
enum bpf_arg_type arg2_type;
@@ -151,7 +152,8 @@ struct bpf_verifier_ops {
*/
bool (*is_valid_access)(int off, int size, enum bpf_access_type type,
enum bpf_reg_type *reg_type);
-
+ int (*gen_prologue)(struct bpf_insn *insn, bool direct_write,
+ const struct bpf_prog *prog);
u32 (*convert_ctx_access)(enum bpf_access_type type, int dst_reg,
int src_reg, int ctx_off,
struct bpf_insn *insn, struct bpf_prog *prog);
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 4c5662f05bda..c6dab3f7457c 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -676,13 +676,23 @@ struct sk_buff {
*/
kmemcheck_bitfield_begin(flags1);
__u16 queue_mapping;
+
+/* if you move cloned around you also must adapt those constants */
+#ifdef __BIG_ENDIAN_BITFIELD
+#define CLONED_MASK (1 << 7)
+#else
+#define CLONED_MASK 1
+#endif
+#define CLONED_OFFSET() offsetof(struct sk_buff, __cloned_offset)
+
+ __u8 __cloned_offset[0];
__u8 cloned:1,
nohdr:1,
fclone:2,
peeked:1,
head_frag:1,
- xmit_more:1;
- /* one bit hole */
+ xmit_more:1,
+ __unused:1; /* one bit hole */
kmemcheck_bitfield_end(flags1);
/* fields enclosed in headers_start/headers_end are copied
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index f896dfac4ac0..e07432b9f8b8 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -398,6 +398,27 @@ enum bpf_func_id {
*/
BPF_FUNC_skb_change_tail,
+ /**
+ * bpf_skb_pull_data(skb, len)
+ * The helper will pull in non-linear data in case the
+ * skb is non-linear and not all of len are part of the
+ * linear section. Only needed for read/write with direct
+ * packet access.
+ * @skb: pointer to skb
+ * @len: len to make read/writeable
+ * Return: 0 on success or negative error
+ */
+ BPF_FUNC_skb_pull_data,
+
+ /**
+ * bpf_csum_update(skb, csum)
+ * Adds csum into skb->csum in case of CHECKSUM_COMPLETE.
+ * @skb: pointer to skb
+ * @csum: csum to add
+ * Return: csum on success or negative error
+ */
+ BPF_FUNC_csum_update,
+
__BPF_FUNC_MAX_ID,
};
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index a5b8bf8cfcfd..39918402e6e9 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -36,6 +36,7 @@ BPF_CALL_2(bpf_map_lookup_elem, struct bpf_map *, map, void *, key)
const struct bpf_func_proto bpf_map_lookup_elem_proto = {
.func = bpf_map_lookup_elem,
.gpl_only = false,
+ .pkt_access = true,
.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
.arg1_type = ARG_CONST_MAP_PTR,
.arg2_type = ARG_PTR_TO_MAP_KEY,
@@ -51,6 +52,7 @@ BPF_CALL_4(bpf_map_update_elem, struct bpf_map *, map, void *, key,
const struct bpf_func_proto bpf_map_update_elem_proto = {
.func = bpf_map_update_elem,
.gpl_only = false,
+ .pkt_access = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_CONST_MAP_PTR,
.arg2_type = ARG_PTR_TO_MAP_KEY,
@@ -67,6 +69,7 @@ BPF_CALL_2(bpf_map_delete_elem, struct bpf_map *, map, void *, key)
const struct bpf_func_proto bpf_map_delete_elem_proto = {
.func = bpf_map_delete_elem,
.gpl_only = false,
+ .pkt_access = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_CONST_MAP_PTR,
.arg2_type = ARG_PTR_TO_MAP_KEY,
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index bc138f34e38c..3a75ee3bdcd1 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -196,6 +196,7 @@ struct verifier_env {
u32 used_map_cnt; /* number of used maps */
u32 id_gen; /* used to generate unique reg IDs */
bool allow_ptr_leaks;
+ bool seen_direct_write;
};
#define BPF_COMPLEXITY_LIMIT_INSNS 65536
@@ -204,6 +205,7 @@ struct verifier_env {
struct bpf_call_arg_meta {
struct bpf_map *map_ptr;
bool raw_mode;
+ bool pkt_access;
int regno;
int access_size;
};
@@ -654,10 +656,17 @@ static int check_map_access(struct verifier_env *env, u32 regno, int off,
#define MAX_PACKET_OFF 0xffff
-static bool may_write_pkt_data(enum bpf_prog_type type)
+static bool may_access_direct_pkt_data(struct verifier_env *env,
+ const struct bpf_call_arg_meta *meta)
{
- switch (type) {
+ switch (env->prog->type) {
+ case BPF_PROG_TYPE_SCHED_CLS:
+ case BPF_PROG_TYPE_SCHED_ACT:
case BPF_PROG_TYPE_XDP:
+ if (meta)
+ return meta->pkt_access;
+
+ env->seen_direct_write = true;
return true;
default:
return false;
@@ -817,7 +826,7 @@ static int check_mem_access(struct verifier_env *env, u32 regno, int off,
err = check_stack_read(state, off, size, value_regno);
}
} else if (state->regs[regno].type == PTR_TO_PACKET) {
- if (t == BPF_WRITE && !may_write_pkt_data(env->prog->type)) {
+ if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL)) {
verbose("cannot write into packet\n");
return -EACCES;
}
@@ -950,8 +959,8 @@ static int check_func_arg(struct verifier_env *env, u32 regno,
return 0;
}
- if (type == PTR_TO_PACKET && !may_write_pkt_data(env->prog->type)) {
- verbose("helper access to the packet is not allowed for clsact\n");
+ if (type == PTR_TO_PACKET && !may_access_direct_pkt_data(env, meta)) {
+ verbose("helper access to the packet is not allowed\n");
return -EACCES;
}
@@ -1191,6 +1200,7 @@ static int check_call(struct verifier_env *env, int func_id)
changes_data = bpf_helper_changes_skb_data(fn->func);
memset(&meta, 0, sizeof(meta));
+ meta.pkt_access = fn->pkt_access;
/* We only support one arg being in raw mode at the moment, which
* is sufficient for the helper functions we have right now.
@@ -2675,18 +2685,35 @@ static void convert_pseudo_ld_imm64(struct verifier_env *env)
*/
static int convert_ctx_accesses(struct verifier_env *env)
{
- struct bpf_insn *insn = env->prog->insnsi;
- int insn_cnt = env->prog->len;
- struct bpf_insn insn_buf[16];
+ const struct bpf_verifier_ops *ops = env->prog->aux->ops;
+ struct bpf_insn insn_buf[16], *insn;
struct bpf_prog *new_prog;
enum bpf_access_type type;
- int i;
+ int i, insn_cnt, cnt;
- if (!env->prog->aux->ops->convert_ctx_access)
+ if (ops->gen_prologue) {
+ cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
+ env->prog);
+ if (cnt >= ARRAY_SIZE(insn_buf)) {
+ verbose("bpf verifier is misconfigured\n");
+ return -EINVAL;
+ } else if (cnt) {
+ new_prog = bpf_patch_insn_single(env->prog, 0,
+ insn_buf, cnt);
+ if (!new_prog)
+ return -ENOMEM;
+ env->prog = new_prog;
+ }
+ }
+
+ if (!ops->convert_ctx_access)
return 0;
+ insn_cnt = env->prog->len;
+ insn = env->prog->insnsi;
+
for (i = 0; i < insn_cnt; i++, insn++) {
- u32 insn_delta, cnt;
+ u32 insn_delta;
if (insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
insn->code == (BPF_LDX | BPF_MEM | BPF_DW))
@@ -2703,9 +2730,8 @@ static int convert_ctx_accesses(struct verifier_env *env)
continue;
}
- cnt = env->prog->aux->ops->
- convert_ctx_access(type, insn->dst_reg, insn->src_reg,
- insn->off, insn_buf, env->prog);
+ cnt = ops->convert_ctx_access(type, insn->dst_reg, insn->src_reg,
+ insn->off, insn_buf, env->prog);
if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
verbose("bpf verifier is misconfigured\n");
return -EINVAL;
diff --git a/net/core/filter.c b/net/core/filter.c
index 298b146b47e7..0920c2ac1d00 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1362,6 +1362,11 @@ static inline int bpf_try_make_writable(struct sk_buff *skb,
return err;
}
+static int bpf_try_make_head_writable(struct sk_buff *skb)
+{
+ return bpf_try_make_writable(skb, skb_headlen(skb));
+}
+
static inline void bpf_push_mac_rcsum(struct sk_buff *skb)
{
if (skb_at_tc_ingress(skb))
@@ -1441,6 +1446,28 @@ static const struct bpf_func_proto bpf_skb_load_bytes_proto = {
.arg4_type = ARG_CONST_STACK_SIZE,
};
+BPF_CALL_2(bpf_skb_pull_data, struct sk_buff *, skb, u32, len)
+{
+ /* Idea is the following: should the needed direct read/write
+ * test fail during runtime, we can pull in more data and redo
+ * again, since implicitly, we invalidate previous checks here.
+ *
+ * Or, since we know how much we need to make read/writeable,
+ * this can be done once at the program beginning for direct
+ * access case. By this we overcome limitations of only current
+ * headroom being accessible.
+ */
+ return bpf_try_make_writable(skb, len ? : skb_headlen(skb));
+}
+
+static const struct bpf_func_proto bpf_skb_pull_data_proto = {
+ .func = bpf_skb_pull_data,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_ANYTHING,
+};
+
BPF_CALL_5(bpf_l3_csum_replace, struct sk_buff *, skb, u32, offset,
u64, from, u64, to, u64, flags)
{
@@ -1567,6 +1594,7 @@ BPF_CALL_5(bpf_csum_diff, __be32 *, from, u32, from_size,
static const struct bpf_func_proto bpf_csum_diff_proto = {
.func = bpf_csum_diff,
.gpl_only = false,
+ .pkt_access = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_STACK,
.arg2_type = ARG_CONST_STACK_SIZE_OR_ZERO,
@@ -1575,6 +1603,26 @@ static const struct bpf_func_proto bpf_csum_diff_proto = {
.arg5_type = ARG_ANYTHING,
};
+BPF_CALL_2(bpf_csum_update, struct sk_buff *, skb, __wsum, csum)
+{
+ /* The interface is to be used in combination with bpf_csum_diff()
+ * for direct packet writes. csum rotation for alignment as well
+ * as emulating csum_sub() can be done from the eBPF program.
+ */
+ if (skb->ip_summed == CHECKSUM_COMPLETE)
+ return (skb->csum = csum_add(skb->csum, csum));
+
+ return -ENOTSUPP;
+}
+
+static const struct bpf_func_proto bpf_csum_update_proto = {
+ .func = bpf_csum_update,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_ANYTHING,
+};
+
static inline int __bpf_rx_skb(struct net_device *dev, struct sk_buff *skb)
{
return dev_forward_skb(dev, skb);
@@ -1602,6 +1650,8 @@ static inline int __bpf_tx_skb(struct net_device *dev, struct sk_buff *skb)
BPF_CALL_3(bpf_clone_redirect, struct sk_buff *, skb, u32, ifindex, u64, flags)
{
struct net_device *dev;
+ struct sk_buff *clone;
+ int ret;
if (unlikely(flags & ~(BPF_F_INGRESS)))
return -EINVAL;
@@ -1610,14 +1660,25 @@ BPF_CALL_3(bpf_clone_redirect, struct sk_buff *, skb, u32, ifindex, u64, flags)
if (unlikely(!dev))
return -EINVAL;
- skb = skb_clone(skb, GFP_ATOMIC);
- if (unlikely(!skb))
+ clone = skb_clone(skb, GFP_ATOMIC);
+ if (unlikely(!clone))
return -ENOMEM;
- bpf_push_mac_rcsum(skb);
+ /* For direct write, we need to keep the invariant that the skbs
+ * we're dealing with need to be uncloned. Should uncloning fail
+ * here, we need to free the just generated clone to unclone once
+ * again.
+ */
+ ret = bpf_try_make_head_writable(skb);
+ if (unlikely(ret)) {
+ kfree_skb(clone);
+ return -ENOMEM;
+ }
+
+ bpf_push_mac_rcsum(clone);
return flags & BPF_F_INGRESS ?
- __bpf_rx_skb(dev, skb) : __bpf_tx_skb(dev, skb);
+ __bpf_rx_skb(dev, clone) : __bpf_tx_skb(dev, clone);
}
static const struct bpf_func_proto bpf_clone_redirect_proto = {
@@ -2063,19 +2124,14 @@ static const struct bpf_func_proto bpf_skb_change_tail_proto = {
bool bpf_helper_changes_skb_data(void *func)
{
- if (func == bpf_skb_vlan_push)
- return true;
- if (func == bpf_skb_vlan_pop)
- return true;
- if (func == bpf_skb_store_bytes)
- return true;
- if (func == bpf_skb_change_proto)
- return true;
- if (func == bpf_skb_change_tail)
- return true;
- if (func == bpf_l3_csum_replace)
- return true;
- if (func == bpf_l4_csum_replace)
+ if (func == bpf_skb_vlan_push ||
+ func == bpf_skb_vlan_pop ||
+ func == bpf_skb_store_bytes ||
+ func == bpf_skb_change_proto ||
+ func == bpf_skb_change_tail ||
+ func == bpf_skb_pull_data ||
+ func == bpf_l3_csum_replace ||
+ func == bpf_l4_csum_replace)
return true;
return false;
@@ -2440,8 +2496,12 @@ tc_cls_act_func_proto(enum bpf_func_id func_id)
return &bpf_skb_store_bytes_proto;
case BPF_FUNC_skb_load_bytes:
return &bpf_skb_load_bytes_proto;
+ case BPF_FUNC_skb_pull_data:
+ return &bpf_skb_pull_data_proto;
case BPF_FUNC_csum_diff:
return &bpf_csum_diff_proto;
+ case BPF_FUNC_csum_update:
+ return &bpf_csum_update_proto;
case BPF_FUNC_l3_csum_replace:
return &bpf_l3_csum_replace_proto;
case BPF_FUNC_l4_csum_replace:
@@ -2533,6 +2593,45 @@ static bool sk_filter_is_valid_access(int off, int size,
return __is_valid_access(off, size, type);
}
+static int tc_cls_act_prologue(struct bpf_insn *insn_buf, bool direct_write,
+ const struct bpf_prog *prog)
+{
+ struct bpf_insn *insn = insn_buf;
+
+ if (!direct_write)
+ return 0;
+
+ /* if (!skb->cloned)
+ * goto start;
+ *
+ * (Fast-path, otherwise approximation that we might be
+ * a clone, do the rest in helper.)
+ */
+ *insn++ = BPF_LDX_MEM(BPF_B, BPF_REG_6, BPF_REG_1, CLONED_OFFSET());
+ *insn++ = BPF_ALU32_IMM(BPF_AND, BPF_REG_6, CLONED_MASK);
+ *insn++ = BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 7);
+
+ /* ret = bpf_skb_pull_data(skb, 0); */
+ *insn++ = BPF_MOV64_REG(BPF_REG_6, BPF_REG_1);
+ *insn++ = BPF_ALU64_REG(BPF_XOR, BPF_REG_2, BPF_REG_2);
+ *insn++ = BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+ BPF_FUNC_skb_pull_data);
+ /* if (!ret)
+ * goto restore;
+ * return TC_ACT_SHOT;
+ */
+ *insn++ = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2);
+ *insn++ = BPF_ALU32_IMM(BPF_MOV, BPF_REG_0, TC_ACT_SHOT);
+ *insn++ = BPF_EXIT_INSN();
+
+ /* restore: */
+ *insn++ = BPF_MOV64_REG(BPF_REG_1, BPF_REG_6);
+ /* start: */
+ *insn++ = prog->insnsi[0];
+
+ return insn - insn_buf;
+}
+
static bool tc_cls_act_is_valid_access(int off, int size,
enum bpf_access_type type,
enum bpf_reg_type *reg_type)
@@ -2810,6 +2909,7 @@ static const struct bpf_verifier_ops tc_cls_act_ops = {
.get_func_proto = tc_cls_act_func_proto,
.is_valid_access = tc_cls_act_is_valid_access,
.convert_ctx_access = tc_cls_act_convert_ctx_access,
+ .gen_prologue = tc_cls_act_prologue,
};
static const struct bpf_verifier_ops xdp_ops = {
generated by cgit v1.2.3 (git 2.0.4) at 2024-05-26 16:11:24 +0000