bpf: Prepare btf_ctx_access for non raw_tp use case
This patch makes a few changes to btf_ctx_access() to prepare
it for non raw_tp use case where the attach_btf_id is not
necessary a BTF_KIND_TYPEDEF.
It moves the "btf_trace_" prefix check and typedef-follow logic to a new
function "check_attach_btf_id()" which is called only once during
bpf_check(). btf_ctx_access() only operates on a BTF_KIND_FUNC_PROTO
type now. That should also be more efficient since it is done only
one instead of every-time check_ctx_access() is called.
"check_attach_btf_id()" needs to find the func_proto type from
the attach_btf_id. It needs to store the result into the
newly added prog->aux->attach_func_proto. func_proto
btf type has no name, so a proper name should be stored into
"attach_func_name" also.
v2:
- Move the "btf_trace_" check to an earlier verifier phase (Alexei)
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191025001811.1718491-1-kafai@fb.com
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index f7557af..128d896 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -336,16 +336,6 @@ static bool btf_type_is_fwd(const struct btf_type *t)
return BTF_INFO_KIND(t->info) == BTF_KIND_FWD;
}
-static bool btf_type_is_func(const struct btf_type *t)
-{
- return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC;
-}
-
-static bool btf_type_is_func_proto(const struct btf_type *t)
-{
- return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC_PROTO;
-}
-
static bool btf_type_nosize(const struct btf_type *t)
{
return btf_type_is_void(t) || btf_type_is_fwd(t) ||
@@ -377,16 +367,6 @@ static bool btf_type_is_array(const struct btf_type *t)
return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY;
}
-static bool btf_type_is_ptr(const struct btf_type *t)
-{
- return BTF_INFO_KIND(t->info) == BTF_KIND_PTR;
-}
-
-static bool btf_type_is_int(const struct btf_type *t)
-{
- return BTF_INFO_KIND(t->info) == BTF_KIND_INT;
-}
-
static bool btf_type_is_var(const struct btf_type *t)
{
return BTF_INFO_KIND(t->info) == BTF_KIND_VAR;
@@ -3442,54 +3422,27 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
{
+ const struct btf_type *t = prog->aux->attach_func_proto;
+ const char *tname = prog->aux->attach_func_name;
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",
+ bpf_log(log, "func '%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;
+ nr_args = btf_type_vlen(t);
+ if (prog->aux->attach_btf_trace) {
+ /* skip first 'void *__data' argument in btf_trace_##name typedef */
+ args++;
+ nr_args--;
+ }
if (arg >= nr_args) {
- bpf_log(log, "raw_tp '%s' doesn't have %d-th argument\n",
+ bpf_log(log, "func '%s' doesn't have %d-th argument\n",
tname, arg);
return false;
}
@@ -3503,7 +3456,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
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",
+ "func '%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)]);
@@ -3526,11 +3479,11 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
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",
+ "func '%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",
+ bpf_log(log, "func '%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;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 16ea3c0..ff52257 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1848,9 +1848,7 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
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;
+ tp_name = prog->aux->attach_func_name;
} else {
if (strncpy_from_user(buf,
u64_to_user_ptr(attr->raw_tracepoint.name),
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 556e82f..c59778c 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9372,6 +9372,52 @@ static void print_verification_stats(struct bpf_verifier_env *env)
env->peak_states, env->longest_mark_read_walk);
}
+static int check_attach_btf_id(struct bpf_verifier_env *env)
+{
+ struct bpf_prog *prog = env->prog;
+ u32 btf_id = prog->aux->attach_btf_id;
+ const struct btf_type *t;
+ const char *tname;
+
+ if (prog->type == BPF_PROG_TYPE_RAW_TRACEPOINT && btf_id) {
+ const char prefix[] = "btf_trace_";
+
+ t = btf_type_by_id(btf_vmlinux, btf_id);
+ if (!t) {
+ verbose(env, "attach_btf_id %u is invalid\n", btf_id);
+ return -EINVAL;
+ }
+ if (!btf_type_is_typedef(t)) {
+ verbose(env, "attach_btf_id %u is not a typedef\n",
+ btf_id);
+ return -EINVAL;
+ }
+ tname = btf_name_by_offset(btf_vmlinux, t->name_off);
+ if (!tname || strncmp(prefix, tname, sizeof(prefix) - 1)) {
+ verbose(env, "attach_btf_id %u points to wrong type name %s\n",
+ btf_id, tname);
+ return -EINVAL;
+ }
+ tname += sizeof(prefix) - 1;
+ t = btf_type_by_id(btf_vmlinux, t->type);
+ if (!btf_type_is_ptr(t))
+ /* should never happen in valid vmlinux build */
+ return -EINVAL;
+ t = btf_type_by_id(btf_vmlinux, t->type);
+ if (!btf_type_is_func_proto(t))
+ /* should never happen in valid vmlinux build */
+ return -EINVAL;
+
+ /* remember two read only pointers that are valid for
+ * the life time of the kernel
+ */
+ prog->aux->attach_func_name = tname;
+ prog->aux->attach_func_proto = t;
+ prog->aux->attach_btf_trace = true;
+ }
+ return 0;
+}
+
int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
union bpf_attr __user *uattr)
{
@@ -9435,9 +9481,13 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
/* Either gcc or pahole or kernel are broken. */
verbose(env, "in-kernel BTF is malformed\n");
ret = PTR_ERR(btf_vmlinux);
- goto err_unlock;
+ goto skip_full_check;
}
+ ret = check_attach_btf_id(env);
+ if (ret)
+ goto skip_full_check;
+
env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT);
if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
env->strict_alignment = true;