Support Android's "baremetal" target

This corresponds to the libcrypto_baremetal build target in Android,
which is an embedded-style platform that uses a subset of the bionic
libc. It will also, eventually, use getentropy for its PRNG.

As part of this, generalize the OPENSSL_TRUSTY exclusion for file BIOs
to OPENSSL_NO_FILESYSTEM. Upstream OpenSSL uses OPENSSL_NO_STDIO, but
that excludes all of FILE entirely. We already require FILE in quite a
few places (urandom.c, self_test.c) for writing to stderr, and FILE is
part of C standard library. So, let's tentatively say that we require
you have FILE and stderr.

Instead, OPENSSL_NO_FILESYSTEM is saying you don't have fopen. You're
still required to have the three std{in,out,err} FILEs, and given a
FILE, you need to allow the standard operations on it. (Possibly in
forms that always fail.)

To keep us honest, whenever a function is excluded, I've dropped it from
the header too, and followed callers up the chain. I have not attempted
to make the tests work when these are excluded. Later CLs in this series
will do the same for NO_SOCK and NO_POSIX_IO. This was a little tedious,
but not too bad.

(I assume we'll end up changing our minds on this a lot. For now, let's
try this.)

I haven't yet restored OPENSSL_RAND_TRUSTY or removed the OPENSSL_TRUSTY
ifdef on file.c. Having a separate CL makes it a bit easier to revert if
something goes wrong.

This depends on
https://android-review.googlesource.com/c/platform/bionic/+/2659335,
which fixes the header bionic uses for getentropy.

Bug: 629, b:291102972
Change-Id: Idd839cd3fa4253128de54bd1be7da261dbcdeb7c
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/61726
Auto-Submit: David Benjamin <davidben@google.com>
Reviewed-by: Bob Beck <bbe@google.com>
Commit-Queue: Bob Beck <bbe@google.com>

crypto/bio/file.c

@@ -73,6 +73,8 @@
 
 #include <openssl/bio.h>
 
+// TODO(crbug.com/boringssl/629): Remove this in favor of the more fine-grained
+// OPENSSL_NO_FILESYSTEM ifdef.
 #if !defined(OPENSSL_TRUSTY)
 
 #include <errno.h>
@@ -89,6 +91,7 @@
 #define BIO_FP_WRITE 0x04
 #define BIO_FP_APPEND 0x08
 
+#if !defined(OPENSSL_NO_FILESYSTEM)
 BIO *BIO_new_file(const char *filename, const char *mode) {
   BIO *ret;
   FILE *file;
@@ -114,6 +117,7 @@ BIO *BIO_new_file(const char *filename, const char *mode) {
 
   return ret;
 }
+#endif  // !OPENSSL_NO_FILESYSTEM
 
 BIO *BIO_new_fp(FILE *stream, int close_flag) {
   BIO *ret = BIO_new(BIO_s_file());
@@ -193,6 +197,7 @@ static long file_ctrl(BIO *b, int cmd, long num, void *ptr) {
       b->ptr = ptr;
       b->init = 1;
       break;
+#if !defined(OPENSSL_NO_FILESYSTEM)
     case BIO_C_SET_FILENAME:
       file_free(b);
       b->shutdown = (int)num & BIO_CLOSE;
@@ -225,6 +230,7 @@ static long file_ctrl(BIO *b, int cmd, long num, void *ptr) {
       b->ptr = fp;
       b->init = 1;
       break;
+#endif  // !OPENSSL_NO_FILESYSTEM
     case BIO_C_GET_FILE_PTR:
       // the ptr parameter is actually a FILE ** in this case.
       if (ptr != NULL) {
@@ -284,6 +290,7 @@ int BIO_set_fp(BIO *bio, FILE *file, int close_flag) {
   return (int)BIO_ctrl(bio, BIO_C_SET_FILE_PTR, close_flag, (char *)file);
 }
 
+#if !defined(OPENSSL_NO_FILESYSTEM)
 int BIO_read_filename(BIO *bio, const char *filename) {
   return (int)BIO_ctrl(bio, BIO_C_SET_FILENAME, BIO_CLOSE | BIO_FP_READ,
                        (char *)filename);
@@ -304,6 +311,7 @@ int BIO_rw_filename(BIO *bio, const char *filename) {
                        BIO_CLOSE | BIO_FP_READ | BIO_FP_WRITE,
                        (char *)filename);
 }
+#endif  // !OPENSSL_NO_FILESYSTEM
 
 long BIO_tell(BIO *bio) { return BIO_ctrl(bio, BIO_C_FILE_TELL, 0, NULL); }
 

crypto/conf/conf.c

@@ -387,7 +387,7 @@ static void clear_comments(CONF *conf, char *p) {
   }
 }
 
-static int def_load_bio(CONF *conf, BIO *in, long *out_error_line) {
+int NCONF_load_bio(CONF *conf, BIO *in, long *out_error_line) {
   static const size_t CONFBUFSIZE = 512;
   int bufnum = 0, i, ii;
   BUF_MEM *buff = NULL;
@@ -585,6 +585,7 @@ err:
   return 0;
 }
 
+#if !defined(OPENSSL_NO_FILESYSTEM)
 int NCONF_load(CONF *conf, const char *filename, long *out_error_line) {
   BIO *in = BIO_new_file(filename, "rb");
   int ret;
@@ -594,15 +595,12 @@ int NCONF_load(CONF *conf, const char *filename, long *out_error_line) {
     return 0;
   }
 
-  ret = def_load_bio(conf, in, out_error_line);
+  ret = NCONF_load_bio(conf, in, out_error_line);
   BIO_free(in);
 
   return ret;
 }
-
-int NCONF_load_bio(CONF *conf, BIO *bio, long *out_error_line) {
-  return def_load_bio(conf, bio, out_error_line);
-}
+#endif  // !OPENSSL_NO_FILESYSTEM
 
 int CONF_parse_list(const char *list, char sep, int remove_whitespace,
                     int (*list_cb)(const char *elem, size_t len, void *usr),

crypto/x509/by_dir.c

@@ -64,7 +64,7 @@
 #include <openssl/thread.h>
 #include <openssl/x509.h>
 
-#if !defined(OPENSSL_TRUSTY)
+#if !defined(OPENSSL_NO_FILESYSTEM)
 
 #include "../internal.h"
 #include "internal.h"
@@ -403,4 +403,4 @@ finish:
   return ok;
 }
 
-#endif  // OPENSSL_TRUSTY
+#endif  // OPENSSL_NO_FILESYSTEM

crypto/x509/by_file.c

@@ -62,7 +62,7 @@
 
 #include "internal.h"
 
-#ifndef OPENSSL_NO_STDIO
+#if !defined(OPENSSL_NO_FILESYSTEM)
 
 static int by_file_ctrl(X509_LOOKUP *ctx, int cmd, const char *argc, long argl,
                         char **ret);
@@ -279,4 +279,4 @@ err:
   return count;
 }
 
-#endif  // OPENSSL_NO_STDIO
+#endif  // !OPENSSL_NO_FILESYSTEM

crypto/x509/x509_d2.c

@@ -57,7 +57,8 @@
 #include <openssl/err.h>
 #include <openssl/x509.h>
 
-#ifndef OPENSSL_NO_STDIO
+#if !defined(OPENSSL_NO_FILESYSTEM)
+
 int X509_STORE_set_default_paths(X509_STORE *ctx) {
   X509_LOOKUP *lookup;
 
@@ -107,4 +108,4 @@ int X509_STORE_load_locations(X509_STORE *ctx, const char *file,
   return 1;
 }
 
-#endif
+#endif  // !OPENSSL_NO_FILESYSTEM

decrepit/ssl/ssl_decrepit.c

@@ -110,7 +110,8 @@
 
 #include <openssl/ssl.h>
 
-#if !defined(OPENSSL_WINDOWS) && !defined(OPENSSL_PNACL)
+#if !defined(OPENSSL_WINDOWS) && !defined(OPENSSL_PNACL) && \
+    !defined(OPENSSL_NO_FILESYSTEM)
 
 #include <dirent.h>
 #include <errno.h>
@@ -162,4 +163,4 @@ int SSL_add_dir_cert_subjects_to_stack(STACK_OF(X509_NAME) *stack,
   return ret;
 }
 
-#endif  // !WINDOWS && !PNACL
+#endif  // !WINDOWS && !PNACL && !OPENSSL_NO_FILESYSTEM

include/openssl/bio.h

@@ -470,9 +470,11 @@ OPENSSL_EXPORT int BIO_get_fd(BIO *bio, int *out_fd);
 // BIO_s_file returns a BIO_METHOD that wraps a |FILE|.
 OPENSSL_EXPORT const BIO_METHOD *BIO_s_file(void);
 
+#if !defined(OPENSSL_NO_FILESYSTEM)
 // BIO_new_file creates a file BIO by opening |filename| with the given mode.
 // See the |fopen| manual page for details of the mode argument.
 OPENSSL_EXPORT BIO *BIO_new_file(const char *filename, const char *mode);
+#endif
 
 // BIO_new_fp creates a new file BIO that wraps the given |FILE|. If
 // |close_flag| is |BIO_CLOSE|, then |fclose| will be called on |stream| when
@@ -488,6 +490,7 @@ OPENSSL_EXPORT int BIO_get_fp(BIO *bio, FILE **out_file);
 // success and zero otherwise.
 OPENSSL_EXPORT int BIO_set_fp(BIO *bio, FILE *file, int close_flag);
 
+#if !defined(OPENSSL_NO_FILESYSTEM)
 // BIO_read_filename opens |filename| for reading and sets the result as the
 // |FILE| for |bio|. It returns one on success and zero otherwise. The |FILE|
 // will be closed when |bio| is freed.
@@ -507,6 +510,7 @@ OPENSSL_EXPORT int BIO_append_filename(BIO *bio, const char *filename);
 // as the |FILE| for |bio|. It returns one on success and zero otherwise. The
 // |FILE| will be closed when |bio| is freed.
 OPENSSL_EXPORT int BIO_rw_filename(BIO *bio, const char *filename);
+#endif  // OPENSSL_NO_FILESYSTEM
 
 // BIO_tell returns the file offset of |bio|, or a negative number on error or
 // if |bio| does not support the operation.

include/openssl/conf.h

@@ -99,12 +99,14 @@ OPENSSL_EXPORT CONF *NCONF_new(void *method);
 // NCONF_free frees all the data owned by |conf| and then |conf| itself.
 OPENSSL_EXPORT void NCONF_free(CONF *conf);
 
+#if !defined(OPENSSL_NO_FILESYSTEM)
 // NCONF_load parses the file named |filename| and adds the values found to
 // |conf|. It returns one on success and zero on error. In the event of an
 // error, if |out_error_line| is not NULL, |*out_error_line| is set to the
 // number of the line that contained the error.
 OPENSSL_EXPORT int NCONF_load(CONF *conf, const char *filename,
                               long *out_error_line);
+#endif
 
 // NCONF_load_bio acts like |NCONF_load| but reads from |bio| rather than from
 // a named file.

include/openssl/ssl.h

@@ -1195,6 +1195,7 @@ OPENSSL_EXPORT int SSL_use_RSAPrivateKey_ASN1(SSL *ssl, const uint8_t *der,
 #define SSL_FILETYPE_PEM 1
 #define SSL_FILETYPE_ASN1 2
 
+#if !defined(OPENSSL_NO_FILESYSTEM)
 OPENSSL_EXPORT int SSL_CTX_use_RSAPrivateKey_file(SSL_CTX *ctx,
                                                   const char *file,
                                                   int type);
@@ -1217,6 +1218,7 @@ OPENSSL_EXPORT int SSL_use_PrivateKey_file(SSL *ssl, const char *file,
 // success and zero on failure.
 OPENSSL_EXPORT int SSL_CTX_use_certificate_chain_file(SSL_CTX *ctx,
                                                       const char *file);
+#endif  // !OPENSSL_NO_FILESYSTEM
 
 // SSL_CTX_set_default_passwd_cb sets the password callback for PEM-based
 // convenience functions called on |ctx|.
@@ -2651,6 +2653,7 @@ OPENSSL_EXPORT void SSL_CTX_set_cert_store(SSL_CTX *ctx, X509_STORE *store);
 // SSL_CTX_get_cert_store returns |ctx|'s certificate store.
 OPENSSL_EXPORT X509_STORE *SSL_CTX_get_cert_store(const SSL_CTX *ctx);
 
+#if !defined(OPENSSL_NO_FILESYSTEM)
 // SSL_CTX_set_default_verify_paths loads the OpenSSL system-default trust
 // anchors into |ctx|'s store. It returns one on success and zero on failure.
 OPENSSL_EXPORT int SSL_CTX_set_default_verify_paths(SSL_CTX *ctx);
@@ -2667,6 +2670,7 @@ OPENSSL_EXPORT int SSL_CTX_set_default_verify_paths(SSL_CTX *ctx);
 OPENSSL_EXPORT int SSL_CTX_load_verify_locations(SSL_CTX *ctx,
                                                  const char *ca_file,
                                                  const char *ca_dir);
+#endif  // !OPENSSL_NO_FILESYSTEM
 
 // SSL_get_verify_result returns the result of certificate verification. It is
 // either |X509_V_OK| or a |X509_V_ERR_*| value.
@@ -2828,20 +2832,24 @@ OPENSSL_EXPORT int SSL_add_client_CA(SSL *ssl, X509 *x509);
 // ownership of |x509|.
 OPENSSL_EXPORT int SSL_CTX_add_client_CA(SSL_CTX *ctx, X509 *x509);
 
+#if !defined(OPENSSL_NO_FILESYSTEM)
 // SSL_load_client_CA_file opens |file| and reads PEM-encoded certificates from
 // it. It returns a newly-allocated stack of the certificate subjects or NULL
 // on error. Duplicates in |file| are ignored.
 OPENSSL_EXPORT STACK_OF(X509_NAME) *SSL_load_client_CA_file(const char *file);
+#endif
 
 // SSL_dup_CA_list makes a deep copy of |list|. It returns the new list on
 // success or NULL on allocation error.
 OPENSSL_EXPORT STACK_OF(X509_NAME) *SSL_dup_CA_list(STACK_OF(X509_NAME) *list);
 
+#if !defined(OPENSSL_NO_FILESYSTEM)
 // SSL_add_file_cert_subjects_to_stack behaves like |SSL_load_client_CA_file|
 // but appends the result to |out|. It returns one on success or zero on
 // error.
 OPENSSL_EXPORT int SSL_add_file_cert_subjects_to_stack(STACK_OF(X509_NAME) *out,
                                                        const char *file);
+#endif
 
 // SSL_add_bio_cert_subjects_to_stack behaves like
 // |SSL_add_file_cert_subjects_to_stack| but reads from |bio|.
@@ -5110,12 +5118,14 @@ OPENSSL_EXPORT int SSL_CTX_set_tmp_ecdh(SSL_CTX *ctx, const EC_KEY *ec_key);
 // |ec_key|'s curve. The remainder of |ec_key| is ignored.
 OPENSSL_EXPORT int SSL_set_tmp_ecdh(SSL *ssl, const EC_KEY *ec_key);
 
+#if !defined(OPENSSL_NO_FILESYSTEM)
 // SSL_add_dir_cert_subjects_to_stack lists files in directory |dir|. It calls
 // |SSL_add_file_cert_subjects_to_stack| on each file and returns one on success
 // or zero on error. This function is only available from the libdecrepit
 // library.
 OPENSSL_EXPORT int SSL_add_dir_cert_subjects_to_stack(STACK_OF(X509_NAME) *out,
                                                       const char *dir);
+#endif
 
 // SSL_CTX_enable_tls_channel_id calls |SSL_CTX_set_tls_channel_id_enabled|.
 OPENSSL_EXPORT int SSL_CTX_enable_tls_channel_id(SSL_CTX *ctx);

include/openssl/target.h

@@ -70,10 +70,13 @@
 #define OPENSSL_WINDOWS
 #endif
 
-// Trusty isn't Linux but currently defines __linux__. As a workaround, we
-// exclude it here.
+// Trusty and Android baremetal aren't't Linux but currently define __linux__.
+// As a workaround, we exclude them here.
+//
 // TODO(b/169780122): Remove this workaround once Trusty no longer defines it.
-#if defined(__linux__) && !defined(__TRUSTY__)
+// TODO(b/291101350): Remove this workaround once Android baremetal no longer
+// defines it.
+#if defined(__linux__) && !defined(__TRUSTY__) && !defined(ANDROID_BAREMETAL)
 #define OPENSSL_LINUX
 #endif
 
@@ -88,6 +91,7 @@
 // platforms must introduce their own defines.
 #if defined(__TRUSTY__)
 #define OPENSSL_TRUSTY
+#define OPENSSL_NO_FILESYSTEM
 #define OPENSSL_NO_POSIX_IO
 #define OPENSSL_NO_SOCK
 #define OPENSSL_NO_THREADS_CORRUPT_MEMORY_AND_LEAK_SECRETS_IF_THREADED
@@ -97,6 +101,17 @@
 // other platform is not supported. Other embedded platforms must introduce
 // their own defines.
 #if defined(OPENSSL_NANOLIBC)
+#define OPENSSL_NO_FILESYSTEM
+#define OPENSSL_NO_POSIX_IO
+#define OPENSSL_NO_SOCK
+#define OPENSSL_NO_THREADS_CORRUPT_MEMORY_AND_LEAK_SECRETS_IF_THREADED
+#endif
+
+// Android baremetal is an embedded target that uses a subset of bionic.
+// Defining this on any other platform is not supported. Other embedded
+// platforms must introduce their own defines.
+#if defined(ANDROID_BAREMETAL)
+#define OPENSSL_NO_FILESYSTEM
 #define OPENSSL_NO_POSIX_IO
 #define OPENSSL_NO_SOCK
 #define OPENSSL_NO_THREADS_CORRUPT_MEMORY_AND_LEAK_SECRETS_IF_THREADED

include/openssl/x509.h

@@ -2852,8 +2852,10 @@ OPENSSL_EXPORT X509 *X509_STORE_CTX_get0_cert(X509_STORE_CTX *ctx);
 OPENSSL_EXPORT X509_LOOKUP *X509_STORE_add_lookup(X509_STORE *v,
                                                   X509_LOOKUP_METHOD *m);
 
+#if !defined(OPENSSL_NO_FILESYSTEM)
 OPENSSL_EXPORT X509_LOOKUP_METHOD *X509_LOOKUP_hash_dir(void);
 OPENSSL_EXPORT X509_LOOKUP_METHOD *X509_LOOKUP_file(void);
+#endif
 
 OPENSSL_EXPORT int X509_STORE_add_cert(X509_STORE *ctx, X509 *x);
 OPENSSL_EXPORT int X509_STORE_add_crl(X509_STORE *ctx, X509_CRL *x);
@@ -2864,7 +2866,7 @@ OPENSSL_EXPORT int X509_STORE_get_by_subject(X509_STORE_CTX *vs, int type,
 OPENSSL_EXPORT int X509_LOOKUP_ctrl(X509_LOOKUP *ctx, int cmd, const char *argc,
                                     long argl, char **ret);
 
-#ifndef OPENSSL_NO_STDIO
+#if !defined(OPENSSL_NO_FILESYSTEM)
 OPENSSL_EXPORT int X509_load_cert_file(X509_LOOKUP *ctx, const char *file,
                                        int type);
 OPENSSL_EXPORT int X509_load_crl_file(X509_LOOKUP *ctx, const char *file,
@@ -2880,7 +2882,7 @@ OPENSSL_EXPORT int X509_LOOKUP_by_subject(X509_LOOKUP *ctx, int type,
                                           X509_NAME *name, X509_OBJECT *ret);
 OPENSSL_EXPORT int X509_LOOKUP_shutdown(X509_LOOKUP *ctx);
 
-#ifndef OPENSSL_NO_STDIO
+#if !defined(OPENSSL_NO_FILESYSTEM)
 OPENSSL_EXPORT int X509_STORE_load_locations(X509_STORE *ctx, const char *file,
                                              const char *dir);
 OPENSSL_EXPORT int X509_STORE_set_default_paths(X509_STORE *ctx);

ssl/ssl_file.cc

@@ -199,6 +199,11 @@ static int add_bio_cert_subjects_to_stack(STACK_OF(X509_NAME) *out, BIO *bio,
   return 1;
 }
 
+int SSL_add_bio_cert_subjects_to_stack(STACK_OF(X509_NAME) *out, BIO *bio) {
+  return add_bio_cert_subjects_to_stack(out, bio, /*allow_empty=*/true);
+}
+
+#if !defined(OPENSSL_NO_FILESYSTEM)
 STACK_OF(X509_NAME) *SSL_load_client_CA_file(const char *file) {
   bssl::UniquePtr<BIO> in(BIO_new_file(file, "r"));
   if (in == nullptr) {
@@ -222,10 +227,6 @@ int SSL_add_file_cert_subjects_to_stack(STACK_OF(X509_NAME) *out,
   return SSL_add_bio_cert_subjects_to_stack(out, in.get());
 }
 
-int SSL_add_bio_cert_subjects_to_stack(STACK_OF(X509_NAME) *out, BIO *bio) {
-  return add_bio_cert_subjects_to_stack(out, bio, /*allow_empty=*/true);
-}
-
 int SSL_use_certificate_file(SSL *ssl, const char *file, int type) {
   int reason_code;
   BIO *in;
@@ -544,6 +545,7 @@ end:
   BIO_free(in);
   return ret;
 }
+#endif  // !OPENSSL_NO_FILESYSTEM
 
 void SSL_CTX_set_default_passwd_cb(SSL_CTX *ctx, pem_password_cb *cb) {
   ctx->default_passwd_callback = cb;

ssl/ssl_x509.cc

@@ -695,6 +695,7 @@ void SSL_CTX_set_verify_depth(SSL_CTX *ctx, int depth) {
   X509_VERIFY_PARAM_set_depth(ctx->param, depth);
 }
 
+#if !defined(OPENSSL_NO_FILESYSTEM)
 int SSL_CTX_set_default_verify_paths(SSL_CTX *ctx) {
   check_ssl_ctx_x509_method(ctx);
   return X509_STORE_set_default_paths(ctx->cert_store);
@@ -705,6 +706,7 @@ int SSL_CTX_load_verify_locations(SSL_CTX *ctx, const char *ca_file,
   check_ssl_ctx_x509_method(ctx);
   return X509_STORE_load_locations(ctx->cert_store, ca_file, ca_dir);
 }
+#endif  // !OPENSSL_NO_FILESYSTEM
 
 long SSL_get_verify_result(const SSL *ssl) {
   check_ssl_x509_method(ssl);