From 4311998718c9270ded76c982c31156a311e461cf Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Sun, 7 Apr 2024 19:57:40 +0200 Subject: X.509: Introduce scope-based x509_certificate allocation Add a DEFINE_FREE() clause for x509_certificate structs and use it in x509_cert_parse() and x509_key_preparse(). These are the only functions where scope-based x509_certificate allocation currently makes sense. A third user will be introduced with the forthcoming SPDM library (Security Protocol and Data Model) for PCI device authentication. Unlike most other DEFINE_FREE() clauses, this one checks for IS_ERR() instead of NULL before calling x509_free_certificate() at end of scope. That's because the "constructor" of x509_certificate structs, x509_cert_parse(), returns a valid pointer or an ERR_PTR(), but never NULL. Comparing the Assembler output before/after has shown they are identical, save for the fact that gcc-12 always generates two return paths when __cleanup() is used, one for the success case and one for the error case. In x509_cert_parse(), add a hint for the compiler that kzalloc() never returns an ERR_PTR(). Otherwise the compiler adds a gratuitous IS_ERR() check on return. Introduce an assume() macro for this which can be re-used elsewhere in the kernel to provide hints for the compiler. Suggested-by: Jonathan Cameron Link: https://lore.kernel.org/all/20231003153937.000034ca@Huawei.com/ Link: https://lwn.net/Articles/934679/ Signed-off-by: Lukas Wunner Signed-off-by: Herbert Xu --- crypto/asymmetric_keys/x509_cert_parser.c | 43 ++++++++++++------------------- 1 file changed, 16 insertions(+), 27 deletions(-) (limited to 'crypto/asymmetric_keys/x509_cert_parser.c') diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c index 964208d1..a814e5f1 100644 --- a/crypto/asymmetric_keys/x509_cert_parser.c +++ b/crypto/asymmetric_keys/x509_cert_parser.c @@ -60,24 +60,24 @@ EXPORT_SYMBOL_GPL(x509_free_certificate); */ struct x509_certificate *x509_cert_parse(const void *data, size_t datalen) { - struct x509_certificate *cert; - struct x509_parse_context *ctx; + struct x509_certificate *cert __free(x509_free_certificate); + struct x509_parse_context *ctx __free(kfree) = NULL; struct asymmetric_key_id *kid; long ret; - ret = -ENOMEM; cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL); + assume(!IS_ERR(cert)); /* Avoid gratuitous IS_ERR() check on return */ if (!cert) - goto error_no_cert; + return ERR_PTR(-ENOMEM); cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL); if (!cert->pub) - goto error_no_ctx; + return ERR_PTR(-ENOMEM); cert->sig = kzalloc(sizeof(struct public_key_signature), GFP_KERNEL); if (!cert->sig) - goto error_no_ctx; + return ERR_PTR(-ENOMEM); ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL); if (!ctx) - goto error_no_ctx; + return ERR_PTR(-ENOMEM); ctx->cert = cert; ctx->data = (unsigned long)data; @@ -85,7 +85,7 @@ struct x509_certificate *x509_cert_parse(const void *data, size_t datalen) /* Attempt to decode the certificate */ ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen); if (ret < 0) - goto error_decode; + return ERR_PTR(ret); /* Decode the AuthorityKeyIdentifier */ if (ctx->raw_akid) { @@ -95,20 +95,19 @@ struct x509_certificate *x509_cert_parse(const void *data, size_t datalen) ctx->raw_akid, ctx->raw_akid_size); if (ret < 0) { pr_warn("Couldn't decode AuthKeyIdentifier\n"); - goto error_decode; + return ERR_PTR(ret); } } - ret = -ENOMEM; cert->pub->key = kmemdup(ctx->key, ctx->key_size, GFP_KERNEL); if (!cert->pub->key) - goto error_decode; + return ERR_PTR(-ENOMEM); cert->pub->keylen = ctx->key_size; cert->pub->params = kmemdup(ctx->params, ctx->params_size, GFP_KERNEL); if (!cert->pub->params) - goto error_decode; + return ERR_PTR(-ENOMEM); cert->pub->paramlen = ctx->params_size; cert->pub->algo = ctx->key_algo; @@ -116,33 +115,23 @@ struct x509_certificate *x509_cert_parse(const void *data, size_t datalen) /* Grab the signature bits */ ret = x509_get_sig_params(cert); if (ret < 0) - goto error_decode; + return ERR_PTR(ret); /* Generate cert issuer + serial number key ID */ kid = asymmetric_key_generate_id(cert->raw_serial, cert->raw_serial_size, cert->raw_issuer, cert->raw_issuer_size); - if (IS_ERR(kid)) { - ret = PTR_ERR(kid); - goto error_decode; - } + if (IS_ERR(kid)) + return ERR_CAST(kid); cert->id = kid; /* Detect self-signed certificates */ ret = x509_check_for_self_signed(cert); if (ret < 0) - goto error_decode; - - kfree(ctx); - return cert; + return ERR_PTR(ret); -error_decode: - kfree(ctx); -error_no_ctx: - x509_free_certificate(cert); -error_no_cert: - return ERR_PTR(ret); + return_ptr(cert); } EXPORT_SYMBOL_GPL(x509_cert_parse); -- cgit v1.2.3