Now that struct bpf_key is an opaque structure only containing a
pointer to the key, make it an alias for the key itself and thus
eliminate the need to allocate and free the container. Because the
return value of bpf_lookup_system_key() is now overloaded with 0 being
a legitimate built in key identifier being the same value as NULL
indicating failure, key id 0 is swizzled to -1 to distinguish it again
and swizzled back in bpf_key_put() and bpf_verify_pkcs7_signature() to
ensure correctness.
Signed-off-by: James Bottomley <james.bottom...@hansenpartnership.com>
---
v2: keep empty struct bpf_key to avoid BTF problems and swizzle 0 key id.
---
kernel/trace/bpf_trace.c | 43 +++++++++++++++-------------------------
1 file changed, 16 insertions(+), 27 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index c0ccd55a4d91..7242167fd4b6 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1242,9 +1242,11 @@ static const struct bpf_func_proto
bpf_get_func_arg_cnt_proto = {
};
#ifdef CONFIG_KEYS
+/* BTF requires this even if it serves no purpose */
struct bpf_key {
- struct key *key;
};
+/* conventional value to replace zero return which would become NULL */
+const u64 BUILTIN_KEY = -1LL;
__bpf_kfunc_start_defs();
@@ -1276,7 +1278,6 @@ __bpf_kfunc_start_defs();
__bpf_kfunc struct bpf_key *bpf_lookup_user_key(s32 serial, u64 flags)
{
key_ref_t key_ref;
- struct bpf_key *bkey;
if (flags & ~KEY_LOOKUP_ALL)
return NULL;
@@ -1289,15 +1290,7 @@ __bpf_kfunc struct bpf_key *bpf_lookup_user_key(s32
serial, u64 flags)
if (IS_ERR(key_ref))
return NULL;
- bkey = kmalloc(sizeof(*bkey), GFP_KERNEL);
- if (!bkey) {
- key_put(key_ref_to_ptr(key_ref));
- return NULL;
- }
-
- bkey->key = key_ref_to_ptr(key_ref);
-
- return bkey;
+ return (struct bpf_key *)key_ref_to_ptr(key_ref);
}
/**
@@ -1323,18 +1316,10 @@ __bpf_kfunc struct bpf_key *bpf_lookup_user_key(s32
serial, u64 flags)
*/
__bpf_kfunc struct bpf_key *bpf_lookup_system_key(u64 id)
{
- struct bpf_key *bkey;
-
if (system_keyring_id_check(id) < 0)
return NULL;
- bkey = kmalloc(sizeof(*bkey), GFP_ATOMIC);
- if (!bkey)
- return NULL;
-
- bkey->key = (struct key *)(unsigned long)id;
-
- return bkey;
+ return (struct bpf_key *)(unsigned long)(id ? id : BUILTIN_KEY);
}
/**
@@ -1346,10 +1331,11 @@ __bpf_kfunc struct bpf_key *bpf_lookup_system_key(u64
id)
*/
__bpf_kfunc void bpf_key_put(struct bpf_key *bkey)
{
- if (system_keyring_id_check((unsigned long)bkey->key) < 0)
- key_put(bkey->key);
+ struct key *key = (struct key *)bkey;
- kfree(bkey);
+ if (system_keyring_id_check((unsigned long)key) < 0 &&
+ (unsigned long)key != BUILTIN_KEY)
+ key_put(key);
}
#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
@@ -1370,11 +1356,15 @@ __bpf_kfunc int bpf_verify_pkcs7_signature(struct
bpf_dynptr *data_p,
{
struct bpf_dynptr_kern *data_ptr = (struct bpf_dynptr_kern *)data_p;
struct bpf_dynptr_kern *sig_ptr = (struct bpf_dynptr_kern *)sig_p;
+ struct key *key = (struct key *)trusted_keyring;
const void *data, *sig;
u32 data_len, sig_len;
int ret;
- if (system_keyring_id_check((unsigned long)trusted_keyring->key) < 0) {
+ if ((unsigned long)key == BUILTIN_KEY)
+ key = NULL;
+
+ if (system_keyring_id_check((unsigned long)key) < 0) {
/*
* Do the permission check deferred in bpf_lookup_user_key().
* See bpf_lookup_user_key() for more details.
@@ -1383,7 +1373,7 @@ __bpf_kfunc int bpf_verify_pkcs7_signature(struct
bpf_dynptr *data_p,
* it is already done by keyring_search() called by
* find_asymmetric_key().
*/
- ret = key_validate(trusted_keyring->key);
+ ret = key_validate(key);
if (ret < 0)
return ret;
}
@@ -1393,8 +1383,7 @@ __bpf_kfunc int bpf_verify_pkcs7_signature(struct
bpf_dynptr *data_p,
sig_len = __bpf_dynptr_size(sig_ptr);
sig = __bpf_dynptr_data(sig_ptr, sig_len);
- return verify_pkcs7_signature(data, data_len, sig, sig_len,
- trusted_keyring->key,
+ return verify_pkcs7_signature(data, data_len, sig, sig_len, key,
VERIFYING_UNSPECIFIED_SIGNATURE, NULL,
NULL);
}
--
2.43.0
