On 8/9/22 3:46 PM, Roberto Sassu wrote: [...]
For bpf_key structures obtained from the former lookup function, bpf_verify_pkcs7_signature() completes the permission check deferred by that function by calling key_validate(). key_task_permission() is already called by the PKCS#7 code.
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com
kernel/trace/bpf_trace.c | 56 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 33ca4cfe6e26..79ba8c96735a 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -21,6 +21,7 @@ #include <linux/bsearch.h> #include <linux/sort.h> #include <linux/key.h> +#include <linux/verification.h> #include <net/bpf_sk_storage.h> @@ -1290,6 +1291,47 @@ noinline __weak void bpf_key_put(struct bpf_key *bkey) kfree(bkey); } +#ifdef CONFIG_SYSTEM_DATA_VERIFICATION +/**
- bpf_verify_pkcs7_signature - verify a PKCS#7 signature
- @data_ptr: data to verify
- @sig_ptr: signature of the data
- @trusted_keyring: keyring with keys trusted for signature verification
- Verify the PKCS#7 signature *sig_ptr* against the supplied *data_ptr*
- with keys in a keyring referenced by *trusted_keyring*.
- Return: 0 on success, a negative value on error.
- */
+noinline __weak int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr,
nit: see comment on prev patch for noinline and __weak
struct bpf_dynptr_kern *sig_ptr,struct bpf_key *trusted_keyring)+{
- int ret;
- if (trusted_keyring->valid_ptr) {
/** Do the permission check deferred in bpf_lookup_user_key().** A call to key_task_permission() here would be redundant, as* it is already done by keyring_search() called by* find_asymmetric_key().*/
In this patch and previous one, you describe that calling key_validate() is deferred, but you should also provide the actual rationale for readers on "why" we need to do it.
ret = key_validate(trusted_keyring->key);if (ret < 0)return ret;- }
- return verify_pkcs7_signature(data_ptr->data,
bpf_dynptr_get_size(data_ptr),sig_ptr->data,bpf_dynptr_get_size(sig_ptr),trusted_keyring->key,VERIFYING_UNSPECIFIED_SIGNATURE, NULL,NULL);+} +#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
- __diag_pop();
BTF_SET8_START(key_kfunc_set) @@ -1303,11 +1345,25 @@ static const struct btf_kfunc_id_set bpf_key_kfunc_set = { .owner = THIS_MODULE, .set = &key_kfunc_set, };