Merge branch 'bpf-btf-trace'

Alexei Starovoitov says:

====================
v2->v3:
- while trying to adopt btf-based tracing in production service realized
  that disabling bpf_probe_read() was premature. The real tracing program
  needs to see much more than this type safe tracking can provide.
  With these patches the verifier will be able to see that skb->data
  is a pointer to 'u8 *', but it cannot possibly know how many bytes
  of it is readable. Hence bpf_probe_read() is necessary to do basic
  packet reading from tracing program. Some helper can be introduced to
  solve this particular problem, but there are other similar structures.
  Another issue is bitfield reading. The support for bitfields
  is coming to llvm. libbpf will be supporting it eventually as well,
  but there will be corner cases where bpf_probe_read() is necessary.
  The long term goal is still the same: get rid of probe_read eventually.
- fixed build issue with clang reported by Nathan Chancellor.
- addressed a ton of comments from Andrii.
  bitfields and arrays are explicitly unsupported in btf-based tracking.
  This will be improved in the future.
  Right now the verifier is more strict than necessary.
  In some cases it can fall back to 'scalar' instead of rejecting
  the program, but rejection today allows to make better decisions
  in the future.
- adjusted testcase to demo bitfield and skb->data reading.

v1->v2:
- addressed feedback from Andrii and Eric. Thanks a lot for review!
- added missing check at raw_tp attach time.
- Andrii noticed that expected_attach_type cannot be reused.
  Had to introduce new field to bpf_attr.
- cleaned up logging nicely by introducing bpf_log() helper.
- rebased.

Revolutionize bpf tracing and bpf C programming.
C language allows any pointer to be typecasted to any other pointer
or convert integer to a pointer.
Though bpf verifier is operating at assembly level it has strict type
checking for fixed number of types.
Known types are defined in 'enum bpf_reg_type'.
For example:
PTR_TO_FLOW_KEYS is a pointer to 'struct bpf_flow_keys'
PTR_TO_SOCKET is a pointer to 'struct bpf_sock',
and so on.

When it comes to bpf tracing there are no types to track.
bpf+kprobe receives 'struct pt_regs' as input.
bpf+raw_tracepoint receives raw kernel arguments as an array of u64 values.
It was up to bpf program to interpret these integers.
Typical tracing program looks like:
int bpf_prog(struct pt_regs *ctx)
{
    struct net_device *dev;
    struct sk_buff *skb;
    int ifindex;

    skb = (struct sk_buff *) ctx->di;
    bpf_probe_read(&dev, sizeof(dev), &skb->dev);
    bpf_probe_read(&ifindex, sizeof(ifindex), &dev->ifindex);
}
Addressing mistakes will not be caught by C compiler or by the verifier.
The program above could have typecasted ctx->si to skb and page faulted
on every bpf_probe_read().
bpf_probe_read() allows reading any address and suppresses page faults.
Typical program has hundreds of bpf_probe_read() calls to walk
kernel data structures.
Not only tracing program would be slow, but there was always a risk
that bpf_probe_read() would read mmio region of memory and cause
unpredictable hw behavior.

With introduction of Compile Once Run Everywhere technology in libbpf
and in LLVM and BPF Type Format (BTF) the verifier is finally ready
for the next step in program verification.
Now it can use in-kernel BTF to type check bpf assembly code.

Equivalent program will look like:
struct trace_kfree_skb {
    struct sk_buff *skb;
    void *location;
};
SEC("raw_tracepoint/kfree_skb")
int trace_kfree_skb(struct trace_kfree_skb* ctx)
{
    struct sk_buff *skb = ctx->skb;
    struct net_device *dev;
    int ifindex;

    __builtin_preserve_access_index(({
        dev = skb->dev;
        ifindex = dev->ifindex;
    }));
}

These patches teach bpf verifier to recognize kfree_skb's first argument
as 'struct sk_buff *' because this is what kernel C code is doing.
The bpf program cannot 'cheat' and say that the first argument
to kfree_skb raw_tracepoint is some other type.
The verifier will catch such type mismatch between bpf program
assumption of kernel code and the actual type in the kernel.

Furthermore skb->dev access is type tracked as well.
The verifier can see which field of skb is being read
in bpf assembly. It will match offset to type.
If bpf program has code:
struct net_device *dev = (void *)skb->len;
C compiler will not complain and generate bpf assembly code,
but the verifier will recognize that integer 'len' field
is being accessed at offsetof(struct sk_buff, len) and will reject
further dereference of 'dev' variable because it contains
integer value instead of a pointer.

Such sophisticated type tracking allows calling networking
bpf helpers from tracing programs.
This patchset allows calling bpf_skb_event_output() that dumps
skb data into perf ring buffer.
It greatly improves observability.
Now users can not only see packet lenth of the skb
about to be freed in kfree_skb() kernel function, but can
dump it to user space via perf ring buffer using bpf helper
that was previously available only to TC and socket filters.
See patch 10 for full example.

The end result is safer and faster bpf tracing.
Safer - because type safe direct load can be used most of the time
instead of bpf_probe_read().
Faster - because direct loads are used to walk kernel data structures
instead of bpf_probe_read() calls.
Note that such loads can page fault and are supported by
hidden bpf_probe_read() in interpreter and via exception table
if program is JITed.
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

6 files changed, 577 insertions, 48 deletions

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 29c7c06c6bd6..f7557af39756 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -698,6 +698,13 @@ __printf(4, 5) static void __btf_verifier_log_type(struct btf_verifier_env *env,
 	if (!bpf_verifier_log_needed(log))
 		return;
 
+	/* btf verifier prints all types it is processing via
+	 * btf_verifier_log_type(..., fmt = NULL).
+	 * Skip those prints for in-kernel BTF verification.
+	 */
+	if (log->level == BPF_LOG_KERNEL && !fmt)
+		return;
+
 	__btf_verifier_log(log, "[%u] %s %s%s",
 			   env->log_type_id,
 			   btf_kind_str[kind],
@@ -735,6 +742,8 @@ static void btf_verifier_log_member(struct btf_verifier_env *env,
 	if (!bpf_verifier_log_needed(log))
 		return;
 
+	if (log->level == BPF_LOG_KERNEL && !fmt)
+		return;
 	/* The CHECK_META phase already did a btf dump.
 	 *
 	 * If member is logged again, it must hit an error in
@@ -777,6 +786,8 @@ static void btf_verifier_log_vsi(struct btf_verifier_env *env,
 
 	if (!bpf_verifier_log_needed(log))
 		return;
+	if (log->level == BPF_LOG_KERNEL && !fmt)
+		return;
 	if (env->phase != CHECK_META)
 		btf_verifier_log_type(env, datasec_type, NULL);
 
@@ -802,6 +813,8 @@ static void btf_verifier_log_hdr(struct btf_verifier_env *env,
 	if (!bpf_verifier_log_needed(log))
 		return;
 
+	if (log->level == BPF_LOG_KERNEL)
+		return;
 	hdr = &btf->hdr;
 	__btf_verifier_log(log, "magic: 0x%x\n", hdr->magic);
 	__btf_verifier_log(log, "version: %u\n", hdr->version);
@@ -2405,7 +2418,8 @@ static s32 btf_enum_check_meta(struct btf_verifier_env *env,
 			return -EINVAL;
 		}
 
-
+		if (env->log.level == BPF_LOG_KERNEL)
+			continue;
 		btf_verifier_log(env, "\t%s val=%d\n",
 				 __btf_name_by_offset(btf, enums[i].name_off),
 				 enums[i].val);
@@ -3367,6 +3381,319 @@ errout:
 	return ERR_PTR(err);
 }
 
+extern char __weak _binary__btf_vmlinux_bin_start[];
+extern char __weak _binary__btf_vmlinux_bin_end[];
+
+struct btf *btf_parse_vmlinux(void)
+{
+	struct btf_verifier_env *env = NULL;
+	struct bpf_verifier_log *log;
+	struct btf *btf = NULL;
+	int err;
+
+	env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
+	if (!env)
+		return ERR_PTR(-ENOMEM);
+
+	log = &env->log;
+	log->level = BPF_LOG_KERNEL;
+
+	btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
+	if (!btf) {
+		err = -ENOMEM;
+		goto errout;
+	}
+	env->btf = btf;
+
+	btf->data = _binary__btf_vmlinux_bin_start;
+	btf->data_size = _binary__btf_vmlinux_bin_end -
+		_binary__btf_vmlinux_bin_start;
+
+	err = btf_parse_hdr(env);
+	if (err)
+		goto errout;
+
+	btf->nohdr_data = btf->data + btf->hdr.hdr_len;
+
+	err = btf_parse_str_sec(env);
+	if (err)
+		goto errout;
+
+	err = btf_check_all_metas(env);
+	if (err)
+		goto errout;
+
+	btf_verifier_env_free(env);
+	refcount_set(&btf->refcnt, 1);
+	return btf;
+
+errout:
+	btf_verifier_env_free(env);
+	if (btf) {
+		kvfree(btf->types);
+		kfree(btf);
+	}
+	return ERR_PTR(err);
+}
+
+extern struct btf *btf_vmlinux;
+
+bool btf_ctx_access(int off, int size, enum bpf_access_type type,
+		    const struct bpf_prog *prog,
+		    struct bpf_insn_access_aux *info)
+{
+	struct bpf_verifier_log *log = info->log;
+	u32 btf_id = prog->aux->attach_btf_id;
+	const struct btf_param *args;
+	const struct btf_type *t;
+	const char prefix[] = "btf_trace_";
+	const char *tname;
+	u32 nr_args, arg;
+
+	if (!btf_id)
+		return true;
+
+	if (IS_ERR(btf_vmlinux)) {
+		bpf_log(log, "btf_vmlinux is malformed\n");
+		return false;
+	}
+
+	t = btf_type_by_id(btf_vmlinux, btf_id);
+	if (!t || BTF_INFO_KIND(t->info) != BTF_KIND_TYPEDEF) {
+		bpf_log(log, "btf_id is invalid\n");
+		return false;
+	}
+
+	tname = __btf_name_by_offset(btf_vmlinux, t->name_off);
+	if (strncmp(prefix, tname, sizeof(prefix) - 1)) {
+		bpf_log(log, "btf_id points to wrong type name %s\n", tname);
+		return false;
+	}
+	tname += sizeof(prefix) - 1;
+
+	t = btf_type_by_id(btf_vmlinux, t->type);
+	if (!btf_type_is_ptr(t))
+		return false;
+	t = btf_type_by_id(btf_vmlinux, t->type);
+	if (!btf_type_is_func_proto(t))
+		return false;
+
+	if (off % 8) {
+		bpf_log(log, "raw_tp '%s' offset %d is not multiple of 8\n",
+			tname, off);
+		return false;
+	}
+	arg = off / 8;
+	args = (const struct btf_param *)(t + 1);
+	/* skip first 'void *__data' argument in btf_trace_##name typedef */
+	args++;
+	nr_args = btf_type_vlen(t) - 1;
+	if (arg >= nr_args) {
+		bpf_log(log, "raw_tp '%s' doesn't have %d-th argument\n",
+			tname, arg);
+		return false;
+	}
+
+	t = btf_type_by_id(btf_vmlinux, args[arg].type);
+	/* skip modifiers */
+	while (btf_type_is_modifier(t))
+		t = btf_type_by_id(btf_vmlinux, t->type);
+	if (btf_type_is_int(t))
+		/* accessing a scalar */
+		return true;
+	if (!btf_type_is_ptr(t)) {
+		bpf_log(log,
+			"raw_tp '%s' arg%d '%s' has type %s. Only pointer access is allowed\n",
+			tname, arg,
+			__btf_name_by_offset(btf_vmlinux, t->name_off),
+			btf_kind_str[BTF_INFO_KIND(t->info)]);
+		return false;
+	}
+	if (t->type == 0)
+		/* This is a pointer to void.
+		 * It is the same as scalar from the verifier safety pov.
+		 * No further pointer walking is allowed.
+		 */
+		return true;
+
+	/* this is a pointer to another type */
+	info->reg_type = PTR_TO_BTF_ID;
+	info->btf_id = t->type;
+
+	t = btf_type_by_id(btf_vmlinux, t->type);
+	/* skip modifiers */
+	while (btf_type_is_modifier(t))
+		t = btf_type_by_id(btf_vmlinux, t->type);
+	if (!btf_type_is_struct(t)) {
+		bpf_log(log,
+			"raw_tp '%s' arg%d type %s is not a struct\n",
+			tname, arg, btf_kind_str[BTF_INFO_KIND(t->info)]);
+		return false;
+	}
+	bpf_log(log, "raw_tp '%s' arg%d has btf_id %d type %s '%s'\n",
+		tname, arg, info->btf_id, btf_kind_str[BTF_INFO_KIND(t->info)],
+		__btf_name_by_offset(btf_vmlinux, t->name_off));
+	return true;
+}
+
+int btf_struct_access(struct bpf_verifier_log *log,
+		      const struct btf_type *t, int off, int size,
+		      enum bpf_access_type atype,
+		      u32 *next_btf_id)
+{
+	const struct btf_member *member;
+	const struct btf_type *mtype;
+	const char *tname, *mname;
+	int i, moff = 0, msize;
+
+again:
+	tname = __btf_name_by_offset(btf_vmlinux, t->name_off);
+	if (!btf_type_is_struct(t)) {
+		bpf_log(log, "Type '%s' is not a struct", tname);
+		return -EINVAL;
+	}
+
+	for_each_member(i, t, member) {
+		/* offset of the field in bits */
+		moff = btf_member_bit_offset(t, member);
+
+		if (btf_member_bitfield_size(t, member))
+			/* bitfields are not supported yet */
+			continue;
+
+		if (off + size <= moff / 8)
+			/* won't find anything, field is already too far */
+			break;
+
+		/* type of the field */
+		mtype = btf_type_by_id(btf_vmlinux, member->type);
+		mname = __btf_name_by_offset(btf_vmlinux, member->name_off);
+
+		/* skip modifiers */
+		while (btf_type_is_modifier(mtype))
+			mtype = btf_type_by_id(btf_vmlinux, mtype->type);
+
+		if (btf_type_is_array(mtype))
+			/* array deref is not supported yet */
+			continue;
+
+		if (!btf_type_has_size(mtype) && !btf_type_is_ptr(mtype)) {
+			bpf_log(log, "field %s doesn't have size\n", mname);
+			return -EFAULT;
+		}
+		if (btf_type_is_ptr(mtype))
+			msize = 8;
+		else
+			msize = mtype->size;
+		if (off >= moff / 8 + msize)
+			/* no overlap with member, keep iterating */
+			continue;
+		/* the 'off' we're looking for is either equal to start
+		 * of this field or inside of this struct
+		 */
+		if (btf_type_is_struct(mtype)) {
+			/* our field must be inside that union or struct */
+			t = mtype;
+
+			/* adjust offset we're looking for */
+			off -= moff / 8;
+			goto again;
+		}
+		if (msize != size) {
+			/* field access size doesn't match */
+			bpf_log(log,
+				"cannot access %d bytes in struct %s field %s that has size %d\n",
+				size, tname, mname, msize);
+			return -EACCES;
+		}
+
+		if (btf_type_is_ptr(mtype)) {
+			const struct btf_type *stype;
+
+			stype = btf_type_by_id(btf_vmlinux, mtype->type);
+			/* skip modifiers */
+			while (btf_type_is_modifier(stype))
+				stype = btf_type_by_id(btf_vmlinux, stype->type);
+			if (btf_type_is_struct(stype)) {
+				*next_btf_id = mtype->type;
+				return PTR_TO_BTF_ID;
+			}
+		}
+		/* all other fields are treated as scalars */
+		return SCALAR_VALUE;
+	}
+	bpf_log(log, "struct %s doesn't have field at offset %d\n", tname, off);
+	return -EINVAL;
+}
+
+u32 btf_resolve_helper_id(struct bpf_verifier_log *log, void *fn, int arg)
+{
+	char fnname[KSYM_SYMBOL_LEN + 4] = "btf_";
+	const struct btf_param *args;
+	const struct btf_type *t;
+	const char *tname, *sym;
+	u32 btf_id, i;
+
+	if (IS_ERR(btf_vmlinux)) {
+		bpf_log(log, "btf_vmlinux is malformed\n");
+		return -EINVAL;
+	}
+
+	sym = kallsyms_lookup((long)fn, NULL, NULL, NULL, fnname + 4);
+	if (!sym) {
+		bpf_log(log, "kernel doesn't have kallsyms\n");
+		return -EFAULT;
+	}
+
+	for (i = 1; i <= btf_vmlinux->nr_types; i++) {
+		t = btf_type_by_id(btf_vmlinux, i);
+		if (BTF_INFO_KIND(t->info) != BTF_KIND_TYPEDEF)
+			continue;
+		tname = __btf_name_by_offset(btf_vmlinux, t->name_off);
+		if (!strcmp(tname, fnname))
+			break;
+	}
+	if (i > btf_vmlinux->nr_types) {
+		bpf_log(log, "helper %s type is not found\n", fnname);
+		return -ENOENT;
+	}
+
+	t = btf_type_by_id(btf_vmlinux, t->type);
+	if (!btf_type_is_ptr(t))
+		return -EFAULT;
+	t = btf_type_by_id(btf_vmlinux, t->type);
+	if (!btf_type_is_func_proto(t))
+		return -EFAULT;
+
+	args = (const struct btf_param *)(t + 1);
+	if (arg >= btf_type_vlen(t)) {
+		bpf_log(log, "bpf helper %s doesn't have %d-th argument\n",
+			fnname, arg);
+		return -EINVAL;
+	}
+
+	t = btf_type_by_id(btf_vmlinux, args[arg].type);
+	if (!btf_type_is_ptr(t) || !t->type) {
+		/* anything but the pointer to struct is a helper config bug */
+		bpf_log(log, "ARG_PTR_TO_BTF is misconfigured\n");
+		return -EFAULT;
+	}
+	btf_id = t->type;
+	t = btf_type_by_id(btf_vmlinux, t->type);
+	/* skip modifiers */
+	while (btf_type_is_modifier(t)) {
+		btf_id = t->type;
+		t = btf_type_by_id(btf_vmlinux, t->type);
+	}
+	if (!btf_type_is_struct(t)) {
+		bpf_log(log, "ARG_PTR_TO_BTF is not a struct\n");
+		return -EFAULT;
+	}
+	bpf_log(log, "helper %s arg%d has btf_id %d struct %s\n", fnname + 4,
+		arg, btf_id, __btf_name_by_offset(btf_vmlinux, t->name_off));
+	return btf_id;
+}
+
 void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
 		       struct seq_file *m)
 {
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 66088a9e9b9e..673f5d40a93e 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -30,7 +30,7 @@
 #include <linux/kallsyms.h>
 #include <linux/rcupdate.h>
 #include <linux/perf_event.h>
-
+#include <linux/extable.h>
 #include <asm/unaligned.h>
 
 /* Registers */
@@ -712,6 +712,24 @@ bool is_bpf_text_address(unsigned long addr)
 	return ret;
 }
 
+const struct exception_table_entry *search_bpf_extables(unsigned long addr)
+{
+	const struct exception_table_entry *e = NULL;
+	struct bpf_prog *prog;
+
+	rcu_read_lock();
+	prog = bpf_prog_kallsyms_find(addr);
+	if (!prog)
+		goto out;
+	if (!prog->aux->num_exentries)
+		goto out;
+
+	e = search_extable(prog->aux->extable, prog->aux->num_exentries, addr);
+out:
+	rcu_read_unlock();
+	return e;
+}
+
 int bpf_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
 		    char *sym)
 {
@@ -1291,6 +1309,11 @@ bool bpf_opcode_in_insntable(u8 code)
 }
 
 #ifndef CONFIG_BPF_JIT_ALWAYS_ON
+u64 __weak bpf_probe_read(void * dst, u32 size, const void * unsafe_ptr)
+{
+	memset(dst, 0, size);
+	return -EFAULT;
+}
 /**
  *	__bpf_prog_run - run eBPF program on a given context
  *	@regs: is the array of MAX_BPF_EXT_REG eBPF pseudo-registers
@@ -1310,6 +1333,10 @@ static u64 __no_fgcse ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u6
 		/* Non-UAPI available opcodes. */
 		[BPF_JMP | BPF_CALL_ARGS] = &&JMP_CALL_ARGS,
 		[BPF_JMP | BPF_TAIL_CALL] = &&JMP_TAIL_CALL,
+		[BPF_LDX | BPF_PROBE_MEM | BPF_B] = &&LDX_PROBE_MEM_B,
+		[BPF_LDX | BPF_PROBE_MEM | BPF_H] = &&LDX_PROBE_MEM_H,
+		[BPF_LDX | BPF_PROBE_MEM | BPF_W] = &&LDX_PROBE_MEM_W,
+		[BPF_LDX | BPF_PROBE_MEM | BPF_DW] = &&LDX_PROBE_MEM_DW,
 	};
 #undef BPF_INSN_3_LBL
 #undef BPF_INSN_2_LBL
@@ -1542,6 +1569,16 @@ out:
 	LDST(W,  u32)
 	LDST(DW, u64)
 #undef LDST
+#define LDX_PROBE(SIZEOP, SIZE)						\
+	LDX_PROBE_MEM_##SIZEOP:						\
+		bpf_probe_read(&DST, SIZE, (const void *)(long) SRC);	\
+		CONT;
+	LDX_PROBE(B,  1)
+	LDX_PROBE(H,  2)
+	LDX_PROBE(W,  4)
+	LDX_PROBE(DW, 8)
+#undef LDX_PROBE
+
 	STX_XADD_W: /* lock xadd *(u32 *)(dst_reg + off16) += src_reg */
 		atomic_add((u32) SRC, (atomic_t *)(unsigned long)
 			   (DST + insn->off));
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 82eabd4e38ad..523e3ac15a08 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -23,6 +23,7 @@
 #include <linux/timekeeping.h>
 #include <linux/ctype.h>
 #include <linux/nospec.h>
+#include <uapi/linux/btf.h>
 
 #define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PROG_ARRAY || \
 			   (map)->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY || \
@@ -1565,8 +1566,9 @@ static void bpf_prog_load_fixup_attach_type(union bpf_attr *attr)
 }
 
 static int
-bpf_prog_load_check_attach_type(enum bpf_prog_type prog_type,
-				enum bpf_attach_type expected_attach_type)
+bpf_prog_load_check_attach(enum bpf_prog_type prog_type,
+			   enum bpf_attach_type expected_attach_type,
+			   u32 btf_id)
 {
 	switch (prog_type) {
 	case BPF_PROG_TYPE_CGROUP_SOCK:
@@ -1608,13 +1610,19 @@ bpf_prog_load_check_attach_type(enum bpf_prog_type prog_type,
 		default:
 			return -EINVAL;
 		}
+	case BPF_PROG_TYPE_RAW_TRACEPOINT:
+		if (btf_id > BTF_MAX_TYPE)
+			return -EINVAL;
+		return 0;
 	default:
+		if (btf_id)
+			return -EINVAL;
 		return 0;
 	}
 }
 
 /* last field in 'union bpf_attr' used by this command */
-#define	BPF_PROG_LOAD_LAST_FIELD line_info_cnt
+#define	BPF_PROG_LOAD_LAST_FIELD attach_btf_id
 
 static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
 {
@@ -1656,7 +1664,8 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
 		return -EPERM;
 
 	bpf_prog_load_fixup_attach_type(attr);
-	if (bpf_prog_load_check_attach_type(type, attr->expected_attach_type))
+	if (bpf_prog_load_check_attach(type, attr->expected_attach_type,
+				       attr->attach_btf_id))
 		return -EINVAL;
 
 	/* plain bpf_prog allocation */
@@ -1665,6 +1674,7 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
 		return -ENOMEM;
 
 	prog->expected_attach_type = attr->expected_attach_type;
+	prog->aux->attach_btf_id = attr->attach_btf_id;
 
 	prog->aux->offload_requested = !!attr->prog_ifindex;
 
@@ -1806,17 +1816,52 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
 	struct bpf_raw_tracepoint *raw_tp;
 	struct bpf_raw_event_map *btp;
 	struct bpf_prog *prog;
-	char tp_name[128];
+	const char *tp_name;
+	char buf[128];
 	int tp_fd, err;
 
-	if (strncpy_from_user(tp_name, u64_to_user_ptr(attr->raw_tracepoint.name),
-			      sizeof(tp_name) - 1) < 0)
-		return -EFAULT;
-	tp_name[sizeof(tp_name) - 1] = 0;
+	if (CHECK_ATTR(BPF_RAW_TRACEPOINT_OPEN))
+		return -EINVAL;
+
+	prog = bpf_prog_get(attr->raw_tracepoint.prog_fd);
+	if (IS_ERR(prog))
+		return PTR_ERR(prog);
+
+	if (prog->type != BPF_PROG_TYPE_RAW_TRACEPOINT &&
+	    prog->type != BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE) {
+		err = -EINVAL;
+		goto out_put_prog;
+	}
+
+	if (prog->type == BPF_PROG_TYPE_RAW_TRACEPOINT &&
+	    prog->aux->attach_btf_id) {
+		if (attr->raw_tracepoint.name) {
+			/* raw_tp name should not be specified in raw_tp
+			 * programs that were verified via in-kernel BTF info
+			 */
+			err = -EINVAL;
+			goto out_put_prog;
+		}
+		/* raw_tp name is taken from type name instead */
+		tp_name = kernel_type_name(prog->aux->attach_btf_id);
+		/* skip the prefix */
+		tp_name += sizeof("btf_trace_") - 1;
+	} else {
+		if (strncpy_from_user(buf,
+				      u64_to_user_ptr(attr->raw_tracepoint.name),
+				      sizeof(buf) - 1) < 0) {
+			err = -EFAULT;
+			goto out_put_prog;
+		}
+		buf[sizeof(buf) - 1] = 0;
+		tp_name = buf;
+	}
 
 	btp = bpf_get_raw_tracepoint(tp_name);
-	if (!btp)
-		return -ENOENT;
+	if (!btp) {
+		err = -ENOENT;
+		goto out_put_prog;
+	}
 
 	raw_tp = kzalloc(sizeof(*raw_tp), GFP_USER);
 	if (!raw_tp) {
@@ -1824,38 +1869,27 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
 		goto out_put_btp;
 	}
 	raw_tp->btp = btp;
-
-	prog = bpf_prog_get(attr->raw_tracepoint.prog_fd);
-	if (IS_ERR(prog)) {
-		err = PTR_ERR(prog);
-		goto out_free_tp;
-	}
-	if (prog->type != BPF_PROG_TYPE_RAW_TRACEPOINT &&
-	    prog->type != BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE) {
-		err = -EINVAL;
-		goto out_put_prog;
-	}
+	raw_tp->prog = prog;
 
 	err = bpf_probe_register(raw_tp->btp, prog);
 	if (err)
-		goto out_put_prog;
+		goto out_free_tp;
 
-	raw_tp->prog = prog;
 	tp_fd = anon_inode_getfd("bpf-raw-tracepoint", &bpf_raw_tp_fops, raw_tp,
 				 O_CLOEXEC);
 	if (tp_fd < 0) {
 		bpf_probe_unregister(raw_tp->btp, prog);
 		err = tp_fd;
-		goto out_put_prog;
+		goto out_free_tp;
 	}
 	return tp_fd;
 
-out_put_prog:
-	bpf_prog_put(prog);
 out_free_tp:
 	kfree(raw_tp);
 out_put_btp:
 	bpf_put_raw_tracepoint(btp);
+out_put_prog:
+	bpf_prog_put(prog);
 	return err;
 }
 
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index d3446f018b9a..556e82f8869b 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -205,8 +205,11 @@ struct bpf_call_arg_meta {
 	u64 msize_umax_value;
 	int ref_obj_id;
 	int func_id;
+	u32 btf_id;
 };
 
+struct btf *btf_vmlinux;
+
 static DEFINE_MUTEX(bpf_verifier_lock);
 
 static const struct bpf_line_info *
@@ -243,6 +246,10 @@ void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt,
 	n = min(log->len_total - log->len_used - 1, n);
 	log->kbuf[n] = '\0';
 
+	if (log->level == BPF_LOG_KERNEL) {
+		pr_err("BPF:%s\n", log->kbuf);
+		return;
+	}
 	if (!copy_to_user(log->ubuf + log->len_used, log->kbuf, n + 1))
 		log->len_used += n;
 	else
@@ -280,6 +287,19 @@ __printf(2, 3) static void verbose(void *private_data, const char *fmt, ...)
 	va_end(args);
 }
 
+__printf(2, 3) void bpf_log(struct bpf_verifier_log *log,
+			    const char *fmt, ...)
+{
+	va_list args;
+
+	if (!bpf_verifier_log_needed(log))
+		return;
+
+	va_start(args, fmt);
+	bpf_verifier_vlog(log, fmt, args);
+	va_end(args);
+}
+
 static const char *ltrim(const char *s)
 {
 	while (isspace(*s))
@@ -400,6 +420,7 @@ static const char * const reg_type_str[] = {
 	[PTR_TO_TCP_SOCK_OR_NULL] = "tcp_sock_or_null",
 	[PTR_TO_TP_BUFFER]	= "tp_buffer",
 	[PTR_TO_XDP_SOCK]	= "xdp_sock",
+	[PTR_TO_BTF_ID]		= "ptr_",
 };
 
 static char slot_type_char[] = {
@@ -430,6 +451,12 @@ static struct bpf_func_state *func(struct bpf_verifier_env *env,
 	return cur->frame[reg->frameno];
 }
 
+const char *kernel_type_name(u32 id)
+{
+	return btf_name_by_offset(btf_vmlinux,
+				  btf_type_by_id(btf_vmlinux, id)->name_off);
+}
+
 static void print_verifier_state(struct bpf_verifier_env *env,
 				 const struct bpf_func_state *state)
 {
@@ -454,6 +481,8 @@ static void print_verifier_state(struct bpf_verifier_env *env,
 			/* reg->off should be 0 for SCALAR_VALUE */
 			verbose(env, "%lld", reg->var_off.value + reg->off);
 		} else {
+			if (t == PTR_TO_BTF_ID)
+				verbose(env, "%s", kernel_type_name(reg->btf_id));
 			verbose(env, "(id=%d", reg->id);
 			if (reg_type_may_be_refcounted_or_null(t))
 				verbose(env, ",ref_obj_id=%d", reg->ref_obj_id);
@@ -2331,10 +2360,12 @@ static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
 
 /* check access to 'struct bpf_context' fields.  Supports fixed offsets only */
 static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size,
-			    enum bpf_access_type t, enum bpf_reg_type *reg_type)
+			    enum bpf_access_type t, enum bpf_reg_type *reg_type,
+			    u32 *btf_id)
 {
 	struct bpf_insn_access_aux info = {
 		.reg_type = *reg_type,
+		.log = &env->log,
 	};
 
 	if (env->ops->is_valid_access &&
@@ -2348,7 +2379,10 @@ static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off,
 		 */
 		*reg_type = info.reg_type;
 
-		env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size;
+		if (*reg_type == PTR_TO_BTF_ID)
+			*btf_id = info.btf_id;
+		else
+			env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size;
 		/* remember the offset of last byte accessed in ctx */
 		if (env->prog->aux->max_ctx_offset < off + size)
 			env->prog->aux->max_ctx_offset = off + size;
@@ -2774,6 +2808,53 @@ static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val)
 	return 0;
 }
 
+static int check_ptr_to_btf_access(struct bpf_verifier_env *env,
+				   struct bpf_reg_state *regs,
+				   int regno, int off, int size,
+				   enum bpf_access_type atype,
+				   int value_regno)
+{
+	struct bpf_reg_state *reg = regs + regno;
+	const struct btf_type *t = btf_type_by_id(btf_vmlinux, reg->btf_id);
+	const char *tname = btf_name_by_offset(btf_vmlinux, t->name_off);
+	u32 btf_id;
+	int ret;
+
+	if (atype != BPF_READ) {
+		verbose(env, "only read is supported\n");
+		return -EACCES;
+	}
+
+	if (off < 0) {
+		verbose(env,
+			"R%d is ptr_%s invalid negative access: off=%d\n",
+			regno, tname, off);
+		return -EACCES;
+	}
+	if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
+		char tn_buf[48];
+
+		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
+		verbose(env,
+			"R%d is ptr_%s invalid variable offset: off=%d, var_off=%s\n",
+			regno, tname, off, tn_buf);
+		return -EACCES;
+	}
+
+	ret = btf_struct_access(&env->log, t, off, size, atype, &btf_id);
+	if (ret < 0)
+		return ret;
+
+	if (ret == SCALAR_VALUE) {
+		mark_reg_unknown(env, regs, value_regno);
+		return 0;
+	}
+	mark_reg_known_zero(env, regs, value_regno);
+	regs[value_regno].type = PTR_TO_BTF_ID;
+	regs[value_regno].btf_id = btf_id;
+	return 0;
+}
+
 /* check whether memory at (regno + off) is accessible for t = (read | write)
  * if t==write, value_regno is a register which value is stored into memory
  * if t==read, value_regno is a register which will receive the value from memory
@@ -2834,6 +2915,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 		}
 	} else if (reg->type == PTR_TO_CTX) {
 		enum bpf_reg_type reg_type = SCALAR_VALUE;
+		u32 btf_id = 0;
 
 		if (t == BPF_WRITE && value_regno >= 0 &&
 		    is_pointer_value(env, value_regno)) {
@@ -2845,7 +2927,9 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 		if (err < 0)
 			return err;
 
-		err = check_ctx_access(env, insn_idx, off, size, t, &reg_type);
+		err = check_ctx_access(env, insn_idx, off, size, t, &reg_type, &btf_id);
+		if (err)
+			verbose_linfo(env, insn_idx, "; ");
 		if (!err && t == BPF_READ && value_regno >= 0) {
 			/* ctx access returns either a scalar, or a
 			 * PTR_TO_PACKET[_META,_END]. In the latter
@@ -2864,6 +2948,8 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 				 * a sub-register.
 				 */
 				regs[value_regno].subreg_def = DEF_NOT_SUBREG;
+				if (reg_type == PTR_TO_BTF_ID)
+					regs[value_regno].btf_id = btf_id;
 			}
 			regs[value_regno].type = reg_type;
 		}
@@ -2923,6 +3009,9 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 		err = check_tp_buffer_access(env, reg, regno, off, size);
 		if (!err && t == BPF_READ && value_regno >= 0)
 			mark_reg_unknown(env, regs, value_regno);
+	} else if (reg->type == PTR_TO_BTF_ID) {
+		err = check_ptr_to_btf_access(env, regs, regno, off, size, t,
+					      value_regno);
 	} else {
 		verbose(env, "R%d invalid mem access '%s'\n", regno,
 			reg_type_str[reg->type]);
@@ -3351,6 +3440,22 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
 		expected_type = PTR_TO_SOCKET;
 		if (type != expected_type)
 			goto err_type;
+	} else if (arg_type == ARG_PTR_TO_BTF_ID) {
+		expected_type = PTR_TO_BTF_ID;
+		if (type != expected_type)
+			goto err_type;
+		if (reg->btf_id != meta->btf_id) {
+			verbose(env, "Helper has type %s got %s in R%d\n",
+				kernel_type_name(meta->btf_id),
+				kernel_type_name(reg->btf_id), regno);
+
+			return -EACCES;
+		}
+		if (!tnum_is_const(reg->var_off) || reg->var_off.value || reg->off) {
+			verbose(env, "R%d is a pointer to in-kernel struct with non-zero offset\n",
+				regno);
+			return -EACCES;
+		}
 	} else if (arg_type == ARG_PTR_TO_SPIN_LOCK) {
 		if (meta->func_id == BPF_FUNC_spin_lock) {
 			if (process_spin_lock(env, regno, true))
@@ -3498,6 +3603,7 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
 	case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
 		if (func_id != BPF_FUNC_perf_event_read &&
 		    func_id != BPF_FUNC_perf_event_output &&
+		    func_id != BPF_FUNC_skb_output &&
 		    func_id != BPF_FUNC_perf_event_read_value)
 			goto error;
 		break;
@@ -3585,6 +3691,7 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
 	case BPF_FUNC_perf_event_read:
 	case BPF_FUNC_perf_event_output:
 	case BPF_FUNC_perf_event_read_value:
+	case BPF_FUNC_skb_output:
 		if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
 			goto error;
 		break;
@@ -4039,21 +4146,16 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
 
 	meta.func_id = func_id;
 	/* check args */
-	err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta);
-	if (err)
-		return err;
-	err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta);
-	if (err)
-		return err;
-	err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta);
-	if (err)
-		return err;
-	err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta);
-	if (err)
-		return err;
-	err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta);
-	if (err)
-		return err;
+	for (i = 0; i < 5; i++) {
+		if (fn->arg_type[i] == ARG_PTR_TO_BTF_ID) {
+			if (!fn->btf_id[i])
+				fn->btf_id[i] = btf_resolve_helper_id(&env->log, fn->func, i);
+			meta.btf_id = fn->btf_id[i];
+		}
+		err = check_func_arg(env, BPF_REG_1 + i, fn->arg_type[i], &meta);
+		if (err)
+			return err;
+	}
 
 	err = record_func_map(env, &meta, func_id, insn_idx);
 	if (err)
@@ -7493,6 +7595,7 @@ static bool reg_type_mismatch_ok(enum bpf_reg_type type)
 	case PTR_TO_TCP_SOCK:
 	case PTR_TO_TCP_SOCK_OR_NULL:
 	case PTR_TO_XDP_SOCK:
+	case PTR_TO_BTF_ID:
 		return false;
 	default:
 		return true;
@@ -8634,6 +8737,14 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 		case PTR_TO_XDP_SOCK:
 			convert_ctx_access = bpf_xdp_sock_convert_ctx_access;
 			break;
+		case PTR_TO_BTF_ID:
+			if (type == BPF_WRITE) {
+				verbose(env, "Writes through BTF pointers are not allowed\n");
+				return -EINVAL;
+			}
+			insn->code = BPF_LDX | BPF_PROBE_MEM | BPF_SIZE((insn)->code);
+			env->prog->aux->num_exentries++;
+			continue;
 		default:
 			continue;
 		}
@@ -9294,6 +9405,13 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
 	env->ops = bpf_verifier_ops[env->prog->type];
 	is_priv = capable(CAP_SYS_ADMIN);
 
+	if (!btf_vmlinux && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
+		mutex_lock(&bpf_verifier_lock);
+		if (!btf_vmlinux)
+			btf_vmlinux = btf_parse_vmlinux();
+		mutex_unlock(&bpf_verifier_lock);
+	}
+
 	/* grab the mutex to protect few globals used by verifier */
 	if (!is_priv)
 		mutex_lock(&bpf_verifier_lock);
@@ -9313,6 +9431,13 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
 			goto err_unlock;
 	}
 
+	if (IS_ERR(btf_vmlinux)) {
+		/* Either gcc or pahole or kernel are broken. */
+		verbose(env, "in-kernel BTF is malformed\n");
+		ret = PTR_ERR(btf_vmlinux);
+		goto err_unlock;
+	}
+
 	env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT);
 	if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
 		env->strict_alignment = true;
diff --git a/kernel/extable.c b/kernel/extable.c
index f6c9406eec7d..f6920a11e28a 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -56,6 +56,8 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr)
 	e = search_kernel_exception_table(addr);
 	if (!e)
 		e = search_module_extables(addr);
+	if (!e)
+		e = search_bpf_extables(addr);
 	return e;
 }
 
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 44bd08f2443b..52f7e9d8c29b 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -995,6 +995,8 @@ static const struct bpf_func_proto bpf_perf_event_output_proto_raw_tp = {
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
+extern const struct bpf_func_proto bpf_skb_output_proto;
+
 BPF_CALL_3(bpf_get_stackid_raw_tp, struct bpf_raw_tracepoint_args *, args,
 	   struct bpf_map *, map, u64, flags)
 {
@@ -1053,6 +1055,8 @@ raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 	switch (func_id) {
 	case BPF_FUNC_perf_event_output:
 		return &bpf_perf_event_output_proto_raw_tp;
+	case BPF_FUNC_skb_output:
+		return &bpf_skb_output_proto;
 	case BPF_FUNC_get_stackid:
 		return &bpf_get_stackid_proto_raw_tp;
 	case BPF_FUNC_get_stack:
@@ -1074,7 +1078,7 @@ static bool raw_tp_prog_is_valid_access(int off, int size,
 		return false;
 	if (off % size != 0)
 		return false;
-	return true;
+	return btf_ctx_access(off, size, type, prog, info);
 }
 
 const struct bpf_verifier_ops raw_tracepoint_verifier_ops = {