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Date: Thu, 26 Jan 2023 15:34:37 -0800
From: Joanne Koong <joannelkoong@...il.com>
To: bpf@...r.kernel.org
Cc: daniel@...earbox.net, andrii@...nel.org, martin.lau@...nel.org,
ast@...nel.org, netdev@...r.kernel.org, memxor@...il.com,
kernel-team@...com, Joanne Koong <joannelkoong@...il.com>
Subject: [PATCH v8 bpf-next 3/5] bpf: Add skb dynptrs
Add skb dynptrs, which are dynptrs whose underlying pointer points
to a skb. The dynptr acts on skb data. skb dynptrs have two main
benefits. One is that they allow operations on sizes that are not
statically known at compile-time (eg variable-sized accesses).
Another is that parsing the packet data through dynptrs (instead of
through direct access of skb->data and skb->data_end) can be more
ergonomic and less brittle (eg does not need manual if checking for
being within bounds of data_end).
For bpf prog types that don't support writes on skb data, the dynptr is
read-only (bpf_dynptr_write() will return an error and bpf_dynptr_data()
will return a data slice that is read-only where any writes to it will
be rejected by the verifier).
For reads and writes through the bpf_dynptr_read() and bpf_dynptr_write()
interfaces, reading and writing from/to data in the head as well as from/to
non-linear paged buffers is supported. For data slices (through the
bpf_dynptr_data() interface), if the data is in a paged buffer, the user
must first call bpf_skb_pull_data() to pull the data into the linear
portion.
Any bpf_dynptr_write() automatically invalidates any prior data slices
to the skb dynptr. This is because a bpf_dynptr_write() may be writing
to data in a paged buffer, so it will need to pull the buffer first into
the head. The reason it needs to be pulled instead of writing directly to
the paged buffers is because they may be cloned (only the head of the skb
is by default uncloned). As such, any bpf_dynptr_write() will
automatically have its prior data slices invalidated, even if the write
is to data in the skb head (the verifier has no way of differentiating
whether the write is to the head or paged buffers during program load
time). Please note as well that any other helper calls that change the
underlying packet buffer (eg bpf_skb_pull_data()) invalidates any data
slices of the skb dynptr as well. The stack trace for this is
check_helper_call() -> clear_all_pkt_pointers() ->
__clear_all_pkt_pointers() -> mark_reg_unknown().
For examples of how skb dynptrs can be used, please see the attached
selftests.
Signed-off-by: Joanne Koong <joannelkoong@...il.com>
---
include/linux/bpf.h | 82 +++++++++------
include/linux/filter.h | 18 ++++
include/uapi/linux/bpf.h | 37 +++++--
kernel/bpf/btf.c | 18 ++++
kernel/bpf/helpers.c | 95 ++++++++++++++---
kernel/bpf/verifier.c | 181 ++++++++++++++++++++++++++-------
net/core/filter.c | 60 ++++++++++-
tools/include/uapi/linux/bpf.h | 37 +++++--
8 files changed, 428 insertions(+), 100 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 14a0264fac57..1ac061b64582 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -575,11 +575,14 @@ enum bpf_type_flag {
/* MEM is tagged with rcu and memory access needs rcu_read_lock protection. */
MEM_RCU = BIT(13 + BPF_BASE_TYPE_BITS),
+ /* DYNPTR points to sk_buff */
+ DYNPTR_TYPE_SKB = BIT(14 + BPF_BASE_TYPE_BITS),
+
__BPF_TYPE_FLAG_MAX,
__BPF_TYPE_LAST_FLAG = __BPF_TYPE_FLAG_MAX - 1,
};
-#define DYNPTR_TYPE_FLAG_MASK (DYNPTR_TYPE_LOCAL | DYNPTR_TYPE_RINGBUF)
+#define DYNPTR_TYPE_FLAG_MASK (DYNPTR_TYPE_LOCAL | DYNPTR_TYPE_RINGBUF | DYNPTR_TYPE_SKB)
/* Max number of base types. */
#define BPF_BASE_TYPE_LIMIT (1UL << BPF_BASE_TYPE_BITS)
@@ -1082,6 +1085,35 @@ static __always_inline __nocfi unsigned int bpf_dispatcher_nop_func(
return bpf_func(ctx, insnsi);
}
+/* the implementation of the opaque uapi struct bpf_dynptr */
+struct bpf_dynptr_kern {
+ void *data;
+ /* Size represents the number of usable bytes of dynptr data.
+ * If for example the offset is at 4 for a local dynptr whose data is
+ * of type u64, the number of usable bytes is 4.
+ *
+ * The upper 8 bits are reserved. It is as follows:
+ * Bits 0 - 23 = size
+ * Bits 24 - 30 = dynptr type
+ * Bit 31 = whether dynptr is read-only
+ */
+ u32 size;
+ u32 offset;
+} __aligned(8);
+
+enum bpf_dynptr_type {
+ BPF_DYNPTR_TYPE_INVALID,
+ /* Points to memory that is local to the bpf program */
+ BPF_DYNPTR_TYPE_LOCAL,
+ /* Underlying data is a ringbuf record */
+ BPF_DYNPTR_TYPE_RINGBUF,
+ /* Underlying data is a sk_buff */
+ BPF_DYNPTR_TYPE_SKB,
+};
+
+int bpf_dynptr_check_size(u32 size);
+u32 bpf_dynptr_get_size(const struct bpf_dynptr_kern *ptr);
+
#ifdef CONFIG_BPF_JIT
int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr);
int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr);
@@ -2216,6 +2248,11 @@ static inline bool has_current_bpf_ctx(void)
}
void notrace bpf_prog_inc_misses_counter(struct bpf_prog *prog);
+
+void bpf_dynptr_init(struct bpf_dynptr_kern *ptr, void *data,
+ enum bpf_dynptr_type type, u32 offset, u32 size);
+void bpf_dynptr_set_null(struct bpf_dynptr_kern *ptr);
+void bpf_dynptr_set_rdonly(struct bpf_dynptr_kern *ptr);
#else /* !CONFIG_BPF_SYSCALL */
static inline struct bpf_prog *bpf_prog_get(u32 ufd)
{
@@ -2445,6 +2482,19 @@ static inline void bpf_prog_inc_misses_counter(struct bpf_prog *prog)
static inline void bpf_cgrp_storage_free(struct cgroup *cgroup)
{
}
+
+static inline void bpf_dynptr_init(struct bpf_dynptr_kern *ptr, void *data,
+ enum bpf_dynptr_type type, u32 offset, u32 size)
+{
+}
+
+static inline void bpf_dynptr_set_null(struct bpf_dynptr_kern *ptr)
+{
+}
+
+static inline void bpf_dynptr_set_rdonly(struct bpf_dynptr_kern *ptr)
+{
+}
#endif /* CONFIG_BPF_SYSCALL */
void __bpf_free_used_btfs(struct bpf_prog_aux *aux,
@@ -2863,36 +2913,6 @@ int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
u32 num_args, struct bpf_bprintf_data *data);
void bpf_bprintf_cleanup(struct bpf_bprintf_data *data);
-/* the implementation of the opaque uapi struct bpf_dynptr */
-struct bpf_dynptr_kern {
- void *data;
- /* Size represents the number of usable bytes of dynptr data.
- * If for example the offset is at 4 for a local dynptr whose data is
- * of type u64, the number of usable bytes is 4.
- *
- * The upper 8 bits are reserved. It is as follows:
- * Bits 0 - 23 = size
- * Bits 24 - 30 = dynptr type
- * Bit 31 = whether dynptr is read-only
- */
- u32 size;
- u32 offset;
-} __aligned(8);
-
-enum bpf_dynptr_type {
- BPF_DYNPTR_TYPE_INVALID,
- /* Points to memory that is local to the bpf program */
- BPF_DYNPTR_TYPE_LOCAL,
- /* Underlying data is a kernel-produced ringbuf record */
- BPF_DYNPTR_TYPE_RINGBUF,
-};
-
-void bpf_dynptr_init(struct bpf_dynptr_kern *ptr, void *data,
- enum bpf_dynptr_type type, u32 offset, u32 size);
-void bpf_dynptr_set_null(struct bpf_dynptr_kern *ptr);
-int bpf_dynptr_check_size(u32 size);
-u32 bpf_dynptr_get_size(const struct bpf_dynptr_kern *ptr);
-
#ifdef CONFIG_BPF_LSM
void bpf_cgroup_atype_get(u32 attach_btf_id, int cgroup_atype);
void bpf_cgroup_atype_put(int cgroup_atype);
diff --git a/include/linux/filter.h b/include/linux/filter.h
index ccc4a4a58c72..c87d13954d89 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -1541,4 +1541,22 @@ static __always_inline int __bpf_xdp_redirect_map(struct bpf_map *map, u64 index
return XDP_REDIRECT;
}
+#ifdef CONFIG_NET
+int __bpf_skb_load_bytes(const struct sk_buff *skb, u32 offset, void *to, u32 len);
+int __bpf_skb_store_bytes(struct sk_buff *skb, u32 offset, const void *from,
+ u32 len, u64 flags);
+#else /* CONFIG_NET */
+static inline int __bpf_skb_load_bytes(const struct sk_buff *skb, u32 offset,
+ void *to, u32 len)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int __bpf_skb_store_bytes(struct sk_buff *skb, u32 offset,
+ const void *from, u32 len, u64 flags)
+{
+ return -EOPNOTSUPP;
+}
+#endif /* CONFIG_NET */
+
#endif /* __LINUX_FILTER_H__ */
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index ba0f0cfb5e42..f6910392d339 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5320,22 +5320,45 @@ union bpf_attr {
* Description
* Write *len* bytes from *src* into *dst*, starting from *offset*
* into *dst*.
- * *flags* is currently unused.
+ *
+ * *flags* must be 0 except for skb-type dynptrs.
+ *
+ * For skb-type dynptrs:
+ * * All data slices of the dynptr are automatically
+ * invalidated after **bpf_dynptr_write**\ (). If you wish to
+ * avoid this, please perform the write using direct data slices
+ * instead.
+ *
+ * * For *flags*, please see the flags accepted by
+ * **bpf_skb_store_bytes**\ ().
* Return
* 0 on success, -E2BIG if *offset* + *len* exceeds the length
* of *dst*'s data, -EINVAL if *dst* is an invalid dynptr or if *dst*
- * is a read-only dynptr or if *flags* is not 0.
+ * is a read-only dynptr or if *flags* is not correct. For skb-type dynptrs,
+ * other errors correspond to errors returned by **bpf_skb_store_bytes**\ ().
*
* void *bpf_dynptr_data(const struct bpf_dynptr *ptr, u32 offset, u32 len)
* Description
* Get a pointer to the underlying dynptr data.
*
* *len* must be a statically known value. The returned data slice
- * is invalidated whenever the dynptr is invalidated.
- * Return
- * Pointer to the underlying dynptr data, NULL if the dynptr is
- * read-only, if the dynptr is invalid, or if the offset and length
- * is out of bounds.
+ * is invalidated whenever the dynptr is invalidated. Please note
+ * that if the dynptr is read-only, then the returned data slice will
+ * be read-only.
+ *
+ * For skb-type dynptrs:
+ * * If *offset* + *len* extends into the skb's paged buffers,
+ * the user should manually pull the skb with **bpf_skb_pull_data**\ ()
+ * and try again.
+ *
+ * * The data slice is automatically invalidated anytime
+ * **bpf_dynptr_write**\ () or a helper call that changes
+ * the underlying packet buffer (eg **bpf_skb_pull_data**\ ())
+ * is called.
+ * Return
+ * Pointer to the underlying dynptr data, NULL if the dynptr is invalid,
+ * or if the offset and length is out of bounds or in a paged buffer for
+ * skb-type dynptrs.
*
* s64 bpf_tcp_raw_gen_syncookie_ipv4(struct iphdr *iph, struct tcphdr *th, u32 th_len)
* Description
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index b4da17688c65..35d0780f2eb9 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -207,6 +207,11 @@ enum btf_kfunc_hook {
BTF_KFUNC_HOOK_TRACING,
BTF_KFUNC_HOOK_SYSCALL,
BTF_KFUNC_HOOK_FMODRET,
+ BTF_KFUNC_HOOK_CGROUP_SKB,
+ BTF_KFUNC_HOOK_SCHED_ACT,
+ BTF_KFUNC_HOOK_SK_SKB,
+ BTF_KFUNC_HOOK_SOCKET_FILTER,
+ BTF_KFUNC_HOOK_LWT,
BTF_KFUNC_HOOK_MAX,
};
@@ -7609,6 +7614,19 @@ static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
return BTF_KFUNC_HOOK_TRACING;
case BPF_PROG_TYPE_SYSCALL:
return BTF_KFUNC_HOOK_SYSCALL;
+ case BPF_PROG_TYPE_CGROUP_SKB:
+ return BTF_KFUNC_HOOK_CGROUP_SKB;
+ case BPF_PROG_TYPE_SCHED_ACT:
+ return BTF_KFUNC_HOOK_SCHED_ACT;
+ case BPF_PROG_TYPE_SK_SKB:
+ return BTF_KFUNC_HOOK_SK_SKB;
+ case BPF_PROG_TYPE_SOCKET_FILTER:
+ return BTF_KFUNC_HOOK_SOCKET_FILTER;
+ case BPF_PROG_TYPE_LWT_OUT:
+ case BPF_PROG_TYPE_LWT_IN:
+ case BPF_PROG_TYPE_LWT_XMIT:
+ case BPF_PROG_TYPE_LWT_SEG6LOCAL:
+ return BTF_KFUNC_HOOK_LWT;
default:
return BTF_KFUNC_HOOK_MAX;
}
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 458db2db2f81..a79d522b3a26 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1420,11 +1420,21 @@ static bool bpf_dynptr_is_rdonly(const struct bpf_dynptr_kern *ptr)
return ptr->size & DYNPTR_RDONLY_BIT;
}
+void bpf_dynptr_set_rdonly(struct bpf_dynptr_kern *ptr)
+{
+ ptr->size |= DYNPTR_RDONLY_BIT;
+}
+
static void bpf_dynptr_set_type(struct bpf_dynptr_kern *ptr, enum bpf_dynptr_type type)
{
ptr->size |= type << DYNPTR_TYPE_SHIFT;
}
+static enum bpf_dynptr_type bpf_dynptr_get_type(const struct bpf_dynptr_kern *ptr)
+{
+ return (ptr->size & ~(DYNPTR_RDONLY_BIT)) >> DYNPTR_TYPE_SHIFT;
+}
+
u32 bpf_dynptr_get_size(const struct bpf_dynptr_kern *ptr)
{
return ptr->size & DYNPTR_SIZE_MASK;
@@ -1497,6 +1507,7 @@ static const struct bpf_func_proto bpf_dynptr_from_mem_proto = {
BPF_CALL_5(bpf_dynptr_read, void *, dst, u32, len, const struct bpf_dynptr_kern *, src,
u32, offset, u64, flags)
{
+ enum bpf_dynptr_type type;
int err;
if (!src->data || flags)
@@ -1506,13 +1517,23 @@ BPF_CALL_5(bpf_dynptr_read, void *, dst, u32, len, const struct bpf_dynptr_kern
if (err)
return err;
- /* Source and destination may possibly overlap, hence use memmove to
- * copy the data. E.g. bpf_dynptr_from_mem may create two dynptr
- * pointing to overlapping PTR_TO_MAP_VALUE regions.
- */
- memmove(dst, src->data + src->offset + offset, len);
+ type = bpf_dynptr_get_type(src);
- return 0;
+ switch (type) {
+ case BPF_DYNPTR_TYPE_LOCAL:
+ case BPF_DYNPTR_TYPE_RINGBUF:
+ /* Source and destination may possibly overlap, hence use memmove to
+ * copy the data. E.g. bpf_dynptr_from_mem may create two dynptr
+ * pointing to overlapping PTR_TO_MAP_VALUE regions.
+ */
+ memmove(dst, src->data + src->offset + offset, len);
+ return 0;
+ case BPF_DYNPTR_TYPE_SKB:
+ return __bpf_skb_load_bytes(src->data, src->offset + offset, dst, len);
+ default:
+ WARN_ONCE(true, "bpf_dynptr_read: unknown dynptr type %d\n", type);
+ return -EFAULT;
+ }
}
static const struct bpf_func_proto bpf_dynptr_read_proto = {
@@ -1529,22 +1550,36 @@ static const struct bpf_func_proto bpf_dynptr_read_proto = {
BPF_CALL_5(bpf_dynptr_write, const struct bpf_dynptr_kern *, dst, u32, offset, void *, src,
u32, len, u64, flags)
{
+ enum bpf_dynptr_type type;
int err;
- if (!dst->data || flags || bpf_dynptr_is_rdonly(dst))
+ if (!dst->data || bpf_dynptr_is_rdonly(dst))
return -EINVAL;
err = bpf_dynptr_check_off_len(dst, offset, len);
if (err)
return err;
- /* Source and destination may possibly overlap, hence use memmove to
- * copy the data. E.g. bpf_dynptr_from_mem may create two dynptr
- * pointing to overlapping PTR_TO_MAP_VALUE regions.
- */
- memmove(dst->data + dst->offset + offset, src, len);
+ type = bpf_dynptr_get_type(dst);
- return 0;
+ switch (type) {
+ case BPF_DYNPTR_TYPE_LOCAL:
+ case BPF_DYNPTR_TYPE_RINGBUF:
+ if (flags)
+ return -EINVAL;
+ /* Source and destination may possibly overlap, hence use memmove to
+ * copy the data. E.g. bpf_dynptr_from_mem may create two dynptr
+ * pointing to overlapping PTR_TO_MAP_VALUE regions.
+ */
+ memmove(dst->data + dst->offset + offset, src, len);
+ return 0;
+ case BPF_DYNPTR_TYPE_SKB:
+ return __bpf_skb_store_bytes(dst->data, dst->offset + offset, src, len,
+ flags);
+ default:
+ WARN_ONCE(true, "bpf_dynptr_write: unknown dynptr type %d\n", type);
+ return -EFAULT;
+ }
}
static const struct bpf_func_proto bpf_dynptr_write_proto = {
@@ -1560,6 +1595,8 @@ static const struct bpf_func_proto bpf_dynptr_write_proto = {
BPF_CALL_3(bpf_dynptr_data, const struct bpf_dynptr_kern *, ptr, u32, offset, u32, len)
{
+ enum bpf_dynptr_type type;
+ void *data;
int err;
if (!ptr->data)
@@ -1569,10 +1606,36 @@ BPF_CALL_3(bpf_dynptr_data, const struct bpf_dynptr_kern *, ptr, u32, offset, u3
if (err)
return 0;
- if (bpf_dynptr_is_rdonly(ptr))
- return 0;
+ type = bpf_dynptr_get_type(ptr);
+
+ switch (type) {
+ case BPF_DYNPTR_TYPE_LOCAL:
+ case BPF_DYNPTR_TYPE_RINGBUF:
+ if (bpf_dynptr_is_rdonly(ptr))
+ return 0;
+
+ data = ptr->data;
+ break;
+ case BPF_DYNPTR_TYPE_SKB:
+ {
+ struct sk_buff *skb = ptr->data;
- return (unsigned long)(ptr->data + ptr->offset + offset);
+ /* if the data is paged, the caller needs to pull it first */
+ if (ptr->offset + offset + len > skb_headlen(skb))
+ return 0;
+
+ /* Depending on the prog type, the data slice will be either
+ * read-writable or read-only. The verifier will enforce that
+ * any writes to read-only data slices are rejected
+ */
+ data = skb->data;
+ break;
+ }
+ default:
+ WARN_ONCE(true, "bpf_dynptr_data: unknown dynptr type %d\n", type);
+ return 0;
+ }
+ return (unsigned long)(data + ptr->offset + offset);
}
static const struct bpf_func_proto bpf_dynptr_data_proto = {
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index aedf28ef7f63..2c59975c9c39 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -741,6 +741,8 @@ static enum bpf_dynptr_type arg_to_dynptr_type(enum bpf_arg_type arg_type)
return BPF_DYNPTR_TYPE_LOCAL;
case DYNPTR_TYPE_RINGBUF:
return BPF_DYNPTR_TYPE_RINGBUF;
+ case DYNPTR_TYPE_SKB:
+ return BPF_DYNPTR_TYPE_SKB;
default:
return BPF_DYNPTR_TYPE_INVALID;
}
@@ -1625,6 +1627,12 @@ static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg)
reg->type == PTR_TO_PACKET_END;
}
+static bool reg_is_dynptr_slice_pkt(const struct bpf_reg_state *reg)
+{
+ return base_type(reg->type) == PTR_TO_MEM &&
+ reg->type & DYNPTR_TYPE_SKB;
+}
+
/* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */
static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg,
enum bpf_reg_type which)
@@ -6148,7 +6156,7 @@ static int process_kptr_func(struct bpf_verifier_env *env, int regno,
* type, and declare it as 'const struct bpf_dynptr *' in their prototype.
*/
int process_dynptr_func(struct bpf_verifier_env *env, int regno, int insn_idx,
- enum bpf_arg_type arg_type)
+ enum bpf_arg_type arg_type, int func_id)
{
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
int err;
@@ -6233,6 +6241,9 @@ int process_dynptr_func(struct bpf_verifier_env *env, int regno, int insn_idx,
case DYNPTR_TYPE_RINGBUF:
err_extra = "ringbuf";
break;
+ case DYNPTR_TYPE_SKB:
+ err_extra = "skb ";
+ break;
default:
err_extra = "<unknown>";
break;
@@ -6581,6 +6592,28 @@ int check_func_arg_reg_off(struct bpf_verifier_env *env,
}
}
+static struct bpf_reg_state *get_dynptr_arg_reg(struct bpf_verifier_env *env,
+ const struct bpf_func_proto *fn,
+ struct bpf_reg_state *regs)
+{
+ struct bpf_reg_state *state = NULL;
+ int i;
+
+ for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++)
+ if (arg_type_is_dynptr(fn->arg_type[i])) {
+ if (state) {
+ verbose(env, "verifier internal error: multiple dynptr args\n");
+ return NULL;
+ }
+ state = ®s[BPF_REG_1 + i];
+ }
+
+ if (!state)
+ verbose(env, "verifier internal error: no dynptr arg found\n");
+
+ return state;
+}
+
static int dynptr_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
struct bpf_func_state *state = func(env, reg);
@@ -6607,6 +6640,20 @@ static int dynptr_ref_obj_id(struct bpf_verifier_env *env, struct bpf_reg_state
return state->stack[spi].spilled_ptr.ref_obj_id;
}
+static enum bpf_dynptr_type dynptr_get_type(struct bpf_verifier_env *env,
+ struct bpf_reg_state *reg)
+{
+ struct bpf_func_state *state = func(env, reg);
+ int spi = __get_spi(reg->off);
+
+ if (spi < 0) {
+ verbose(env, "verifier internal error: invalid spi when querying dynptr type\n");
+ return BPF_DYNPTR_TYPE_INVALID;
+ }
+
+ return state->stack[spi].spilled_ptr.dynptr.type;
+}
+
static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
struct bpf_call_arg_meta *meta,
const struct bpf_func_proto *fn,
@@ -6819,7 +6866,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
err = check_mem_size_reg(env, reg, regno, true, meta);
break;
case ARG_PTR_TO_DYNPTR:
- err = process_dynptr_func(env, regno, insn_idx, arg_type);
+ err = process_dynptr_func(env, regno, insn_idx, arg_type, meta->func_id);
if (err)
return err;
break;
@@ -7267,6 +7314,9 @@ static int check_func_proto(const struct bpf_func_proto *fn, int func_id)
/* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
* are now invalid, so turn them into unknown SCALAR_VALUE.
+ *
+ * This also applies to dynptr slices belonging to skb dynptrs,
+ * since these slices point to packet data.
*/
static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
{
@@ -7274,7 +7324,7 @@ static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
struct bpf_reg_state *reg;
bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
- if (reg_is_pkt_pointer_any(reg))
+ if (reg_is_pkt_pointer_any(reg) || reg_is_dynptr_slice_pkt(reg))
__mark_reg_unknown(env, reg);
}));
}
@@ -7958,6 +8008,7 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
int *insn_idx_p)
{
enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
+ enum bpf_dynptr_type dynptr_type = BPF_DYNPTR_TYPE_INVALID;
const struct bpf_func_proto *fn = NULL;
enum bpf_return_type ret_type;
enum bpf_type_flag ret_flag;
@@ -8140,43 +8191,61 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
}
break;
case BPF_FUNC_dynptr_data:
- for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) {
- if (arg_type_is_dynptr(fn->arg_type[i])) {
- struct bpf_reg_state *reg = ®s[BPF_REG_1 + i];
- int id, ref_obj_id;
-
- if (meta.dynptr_id) {
- verbose(env, "verifier internal error: meta.dynptr_id already set\n");
- return -EFAULT;
- }
+ {
+ struct bpf_reg_state *reg;
+ int id, ref_obj_id;
- if (meta.ref_obj_id) {
- verbose(env, "verifier internal error: meta.ref_obj_id already set\n");
- return -EFAULT;
- }
+ reg = get_dynptr_arg_reg(env, fn, regs);
+ if (!reg)
+ return -EFAULT;
- id = dynptr_id(env, reg);
- if (id < 0) {
- verbose(env, "verifier internal error: failed to obtain dynptr id\n");
- return id;
- }
+ if (meta.dynptr_id) {
+ verbose(env, "verifier internal error: meta.dynptr_id already set\n");
+ return -EFAULT;
+ }
+ if (meta.ref_obj_id) {
+ verbose(env, "verifier internal error: meta.ref_obj_id already set\n");
+ return -EFAULT;
+ }
- ref_obj_id = dynptr_ref_obj_id(env, reg);
- if (ref_obj_id < 0) {
- verbose(env, "verifier internal error: failed to obtain dynptr ref_obj_id\n");
- return ref_obj_id;
- }
+ id = dynptr_id(env, reg);
+ if (id < 0) {
+ verbose(env, "verifier internal error: failed to obtain dynptr id\n");
+ return id;
+ }
- meta.dynptr_id = id;
- meta.ref_obj_id = ref_obj_id;
- break;
- }
+ ref_obj_id = dynptr_ref_obj_id(env, reg);
+ if (ref_obj_id < 0) {
+ verbose(env, "verifier internal error: failed to obtain dynptr ref_obj_id\n");
+ return ref_obj_id;
}
- if (i == MAX_BPF_FUNC_REG_ARGS) {
- verbose(env, "verifier internal error: no dynptr in bpf_dynptr_data()\n");
+
+ meta.dynptr_id = id;
+ meta.ref_obj_id = ref_obj_id;
+
+ dynptr_type = dynptr_get_type(env, reg);
+ if (dynptr_type == BPF_DYNPTR_TYPE_INVALID)
return -EFAULT;
- }
+
break;
+ }
+ case BPF_FUNC_dynptr_write:
+ {
+ struct bpf_reg_state *reg;
+
+ reg = get_dynptr_arg_reg(env, fn, regs);
+ if (!reg)
+ return -EFAULT;
+
+ dynptr_type = dynptr_get_type(env, reg);
+ if (dynptr_type == BPF_DYNPTR_TYPE_INVALID)
+ return -EFAULT;
+
+ if (dynptr_type == BPF_DYNPTR_TYPE_SKB)
+ changes_data = true;
+
+ break;
+ }
case BPF_FUNC_user_ringbuf_drain:
err = __check_func_call(env, insn, insn_idx_p, meta.subprogno,
set_user_ringbuf_callback_state);
@@ -8243,6 +8312,28 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
mark_reg_known_zero(env, regs, BPF_REG_0);
regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
regs[BPF_REG_0].mem_size = meta.mem_size;
+ if (func_id == BPF_FUNC_dynptr_data &&
+ dynptr_type == BPF_DYNPTR_TYPE_SKB) {
+ bool seen_direct_write = env->seen_direct_write;
+
+ regs[BPF_REG_0].type |= DYNPTR_TYPE_SKB;
+ if (!may_access_direct_pkt_data(env, NULL, BPF_WRITE))
+ regs[BPF_REG_0].type |= MEM_RDONLY;
+ else
+ /*
+ * Calling may_access_direct_pkt_data() will set
+ * env->seen_direct_write to true if the skb is
+ * writable. As an optimization, we can ignore
+ * setting env->seen_direct_write.
+ *
+ * env->seen_direct_write is used by skb
+ * programs to determine whether the skb's page
+ * buffers should be cloned. Since data slice
+ * writes would only be to the head, we can skip
+ * this.
+ */
+ env->seen_direct_write = seen_direct_write;
+ }
break;
case RET_PTR_TO_MEM_OR_BTF_ID:
{
@@ -8649,6 +8740,7 @@ enum special_kfunc_type {
KF_bpf_list_pop_back,
KF_bpf_cast_to_kern_ctx,
KF_bpf_rdonly_cast,
+ KF_bpf_dynptr_from_skb,
KF_bpf_rcu_read_lock,
KF_bpf_rcu_read_unlock,
};
@@ -8662,6 +8754,7 @@ BTF_ID(func, bpf_list_pop_front)
BTF_ID(func, bpf_list_pop_back)
BTF_ID(func, bpf_cast_to_kern_ctx)
BTF_ID(func, bpf_rdonly_cast)
+BTF_ID(func, bpf_dynptr_from_skb)
BTF_SET_END(special_kfunc_set)
BTF_ID_LIST(special_kfunc_list)
@@ -8673,6 +8766,7 @@ BTF_ID(func, bpf_list_pop_front)
BTF_ID(func, bpf_list_pop_back)
BTF_ID(func, bpf_cast_to_kern_ctx)
BTF_ID(func, bpf_rdonly_cast)
+BTF_ID(func, bpf_dynptr_from_skb)
BTF_ID(func, bpf_rcu_read_lock)
BTF_ID(func, bpf_rcu_read_unlock)
@@ -9263,17 +9357,26 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
return ret;
break;
case KF_ARG_PTR_TO_DYNPTR:
+ {
+ enum bpf_arg_type dynptr_arg_type = ARG_PTR_TO_DYNPTR;
+
if (reg->type != PTR_TO_STACK &&
reg->type != CONST_PTR_TO_DYNPTR) {
verbose(env, "arg#%d expected pointer to stack or dynptr_ptr\n", i);
return -EINVAL;
}
- ret = process_dynptr_func(env, regno, insn_idx,
- ARG_PTR_TO_DYNPTR | MEM_RDONLY);
+ if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_skb])
+ dynptr_arg_type |= MEM_UNINIT | DYNPTR_TYPE_SKB;
+ else
+ dynptr_arg_type |= MEM_RDONLY;
+
+ ret = process_dynptr_func(env, regno, insn_idx, dynptr_arg_type,
+ meta->func_id);
if (ret < 0)
return ret;
break;
+ }
case KF_ARG_PTR_TO_LIST_HEAD:
if (reg->type != PTR_TO_MAP_VALUE &&
reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
@@ -15857,6 +15960,14 @@ static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
desc->func_id == special_kfunc_list[KF_bpf_rdonly_cast]) {
insn_buf[0] = BPF_MOV64_REG(BPF_REG_0, BPF_REG_1);
*cnt = 1;
+ } else if (desc->func_id == special_kfunc_list[KF_bpf_dynptr_from_skb]) {
+ bool is_rdonly = !may_access_direct_pkt_data(env, NULL, BPF_WRITE);
+ struct bpf_insn addr[2] = { BPF_LD_IMM64(BPF_REG_4, is_rdonly) };
+
+ insn_buf[0] = addr[0];
+ insn_buf[1] = addr[1];
+ insn_buf[2] = *insn;
+ *cnt = 3;
}
return 0;
}
diff --git a/net/core/filter.c b/net/core/filter.c
index 6da78b3d381e..ddb47126071a 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1684,8 +1684,8 @@ static inline void bpf_pull_mac_rcsum(struct sk_buff *skb)
skb_postpull_rcsum(skb, skb_mac_header(skb), skb->mac_len);
}
-BPF_CALL_5(bpf_skb_store_bytes, struct sk_buff *, skb, u32, offset,
- const void *, from, u32, len, u64, flags)
+int __bpf_skb_store_bytes(struct sk_buff *skb, u32 offset, const void *from,
+ u32 len, u64 flags)
{
void *ptr;
@@ -1710,6 +1710,12 @@ BPF_CALL_5(bpf_skb_store_bytes, struct sk_buff *, skb, u32, offset,
return 0;
}
+BPF_CALL_5(bpf_skb_store_bytes, struct sk_buff *, skb, u32, offset,
+ const void *, from, u32, len, u64, flags)
+{
+ return __bpf_skb_store_bytes(skb, offset, from, len, flags);
+}
+
static const struct bpf_func_proto bpf_skb_store_bytes_proto = {
.func = bpf_skb_store_bytes,
.gpl_only = false,
@@ -1721,8 +1727,7 @@ static const struct bpf_func_proto bpf_skb_store_bytes_proto = {
.arg5_type = ARG_ANYTHING,
};
-BPF_CALL_4(bpf_skb_load_bytes, const struct sk_buff *, skb, u32, offset,
- void *, to, u32, len)
+int __bpf_skb_load_bytes(const struct sk_buff *skb, u32 offset, void *to, u32 len)
{
void *ptr;
@@ -1741,6 +1746,12 @@ BPF_CALL_4(bpf_skb_load_bytes, const struct sk_buff *, skb, u32, offset,
return -EFAULT;
}
+BPF_CALL_4(bpf_skb_load_bytes, const struct sk_buff *, skb, u32, offset,
+ void *, to, u32, len)
+{
+ return __bpf_skb_load_bytes(skb, offset, to, len);
+}
+
static const struct bpf_func_proto bpf_skb_load_bytes_proto = {
.func = bpf_skb_load_bytes,
.gpl_only = false,
@@ -1852,6 +1863,22 @@ static const struct bpf_func_proto bpf_skb_pull_data_proto = {
.arg2_type = ARG_ANYTHING,
};
+int bpf_dynptr_from_skb(struct sk_buff *skb, u64 flags,
+ struct bpf_dynptr_kern *ptr, int is_rdonly)
+{
+ if (flags) {
+ bpf_dynptr_set_null(ptr);
+ return -EINVAL;
+ }
+
+ bpf_dynptr_init(ptr, skb, BPF_DYNPTR_TYPE_SKB, 0, skb->len);
+
+ if (is_rdonly)
+ bpf_dynptr_set_rdonly(ptr);
+
+ return 0;
+}
+
BPF_CALL_1(bpf_sk_fullsock, struct sock *, sk)
{
return sk_fullsock(sk) ? (unsigned long)sk : (unsigned long)NULL;
@@ -11607,3 +11634,28 @@ bpf_sk_base_func_proto(enum bpf_func_id func_id)
return func;
}
+
+BTF_SET8_START(bpf_kfunc_check_set_skb)
+BTF_ID_FLAGS(func, bpf_dynptr_from_skb)
+BTF_SET8_END(bpf_kfunc_check_set_skb)
+
+static const struct btf_kfunc_id_set bpf_kfunc_set_skb = {
+ .owner = THIS_MODULE,
+ .set = &bpf_kfunc_check_set_skb,
+};
+
+static int __init bpf_kfunc_init(void)
+{
+ int ret;
+
+ ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_kfunc_set_skb);
+ ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_ACT, &bpf_kfunc_set_skb);
+ ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SK_SKB, &bpf_kfunc_set_skb);
+ ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SOCKET_FILTER, &bpf_kfunc_set_skb);
+ ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SKB, &bpf_kfunc_set_skb);
+ ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_OUT, &bpf_kfunc_set_skb);
+ ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_IN, &bpf_kfunc_set_skb);
+ ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_XMIT, &bpf_kfunc_set_skb);
+ return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_SEG6LOCAL, &bpf_kfunc_set_skb);
+}
+late_initcall(bpf_kfunc_init);
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 7f024ac22edd..6b58e5a75fc5 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5320,22 +5320,45 @@ union bpf_attr {
* Description
* Write *len* bytes from *src* into *dst*, starting from *offset*
* into *dst*.
- * *flags* is currently unused.
+ *
+ * *flags* must be 0 except for skb-type dynptrs.
+ *
+ * For skb-type dynptrs:
+ * * All data slices of the dynptr are automatically
+ * invalidated after **bpf_dynptr_write**\ (). If you wish to
+ * avoid this, please perform the write using direct data slices
+ * instead.
+ *
+ * * For *flags*, please see the flags accepted by
+ * **bpf_skb_store_bytes**\ ().
* Return
* 0 on success, -E2BIG if *offset* + *len* exceeds the length
* of *dst*'s data, -EINVAL if *dst* is an invalid dynptr or if *dst*
- * is a read-only dynptr or if *flags* is not 0.
+ * is a read-only dynptr or if *flags* is not correct. For skb-type dynptrs,
+ * other errors correspond to errors returned by **bpf_skb_store_bytes**\ ().
*
* void *bpf_dynptr_data(const struct bpf_dynptr *ptr, u32 offset, u32 len)
* Description
* Get a pointer to the underlying dynptr data.
*
* *len* must be a statically known value. The returned data slice
- * is invalidated whenever the dynptr is invalidated.
- * Return
- * Pointer to the underlying dynptr data, NULL if the dynptr is
- * read-only, if the dynptr is invalid, or if the offset and length
- * is out of bounds.
+ * is invalidated whenever the dynptr is invalidated. Please note
+ * that if the dynptr is read-only, then the returned data slice will
+ * be read-only.
+ *
+ * For skb-type dynptrs:
+ * * If *offset* + *len* extends into the skb's paged buffers,
+ * the user should manually pull the skb with **bpf_skb_pull_data**\ ()
+ * and try again.
+ *
+ * * The data slice is automatically invalidated anytime
+ * **bpf_dynptr_write**\ () or a helper call that changes
+ * the underlying packet buffer (eg **bpf_skb_pull_data**\ ())
+ * is called.
+ * Return
+ * Pointer to the underlying dynptr data, NULL if the dynptr is invalid,
+ * or if the offset and length is out of bounds or in a paged buffer for
+ * skb-type dynptrs.
*
* s64 bpf_tcp_raw_gen_syncookie_ipv4(struct iphdr *iph, struct tcphdr *th, u32 th_len)
* Description
--
2.30.2
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