lib: avoid file descriptor leak when application forks

This makes use of the "e" flag of fopen, provided by the Gnulib's
fopen-gnu module.

Reported by Remi Denis-Courmont in:
https://gitlab.com/gnutls/gnutls/-/issues/985
and fix suggested by Tim Rühsen.

Signed-off-by: Daiki Ueno <ueno@gnu.org>

9 files changed, 21 insertions, 13 deletions

diff --git a/bootstrap.conf b/bootstrap.conf
index dcf346d6c6..3abfe10464 100644
--- a/bootstrap.conf
+++ b/bootstrap.conf
@@ -25,10 +25,10 @@ checkout_only_file=
 local_gl_dir=gl/override/
 required_submodules="tests/suite/tls-fuzzer/python-ecdsa tests/suite/tls-fuzzer/tlsfuzzer tests/suite/tls-fuzzer/tlslite-ng devel/nettle devel/libtasn1"
 
-# Reproduce by: gnulib-tool --import --local-dir=gl/override --lib=libgnu --source-base=gl --m4-base=gl/m4 --doc-base=doc --tests-base=gl/tests --aux-dir=build-aux --with-tests --avoid=alignof-tests --avoid=lock-tests --avoid=lseek-tests --lgpl=2 --no-conditional-dependencies --libtool --macro-prefix=gl --no-vc-files alloca attribute byteswap c-ctype extensions func gendocs getline gettext-h gettimeofday hash-pjw-bare havelib intprops ldd lib-msvc-compat lib-symbol-versions maintainer-makefile manywarnings memmem-simple minmax netdb netinet_in pmccabe2html read-file secure_getenv snprintf stdint strcase strndup strtok_r strverscmp sys_socket sys_stat time_r unistd vasprintf verify vsnprintf warnings
+# Reproduce by: gnulib-tool --import --local-dir=gl/override --lib=libgnu --source-base=gl --m4-base=gl/m4 --doc-base=doc --tests-base=gl/tests --aux-dir=build-aux --with-tests --avoid=alignof-tests --avoid=lock-tests --avoid=lseek-tests --lgpl=2 --no-conditional-dependencies --libtool --macro-prefix=gl --no-vc-files alloca attribute byteswap c-ctype extensions fopen-gnu func gendocs getline gettext-h gettimeofday hash-pjw-bare havelib intprops ldd lib-msvc-compat lib-symbol-versions maintainer-makefile manywarnings memmem-simple minmax netdb netinet_in pmccabe2html read-file secure_getenv snprintf stdint strcase strndup strtok_r strverscmp sys_socket sys_stat time_r unistd vasprintf verify vsnprintf warnings
 
 gnulib_modules="
-alloca attribute byteswap c-ctype c-strcase extensions func gendocs getline gettext-h gettimeofday hash hash-pjw-bare havelib arpa_inet inet_ntop inet_pton intprops ldd lib-msvc-compat lib-symbol-versions maintainer-makefile manywarnings memmem-simple minmax netdb netinet_in pmccabe2html read-file secure_getenv setsockopt snprintf stdint strcase strdup-posix strndup strtok_r strverscmp sys_socket sys_stat sys_types time_r unistd valgrind-tests vasprintf verify vsnprintf warnings
+alloca attribute byteswap c-ctype c-strcase extensions fopen-gnu func gendocs getline gettext-h gettimeofday hash hash-pjw-bare havelib arpa_inet inet_ntop inet_pton intprops ldd lib-msvc-compat lib-symbol-versions maintainer-makefile manywarnings memmem-simple minmax netdb netinet_in pmccabe2html read-file secure_getenv setsockopt snprintf stdint strcase strdup-posix strndup strtok_r strverscmp sys_socket sys_stat sys_types time_r unistd valgrind-tests vasprintf verify vsnprintf warnings
 "
 
 unistring_modules="
diff --git a/lib/auth/psk_passwd.c b/lib/auth/psk_passwd.c
index a0427914f9..7384703bc7 100644
--- a/lib/auth/psk_passwd.c
+++ b/lib/auth/psk_passwd.c
@@ -203,7 +203,7 @@ _gnutls_psk_pwd_find_entry(gnutls_session_t session,
 
 	/* Open the selected password file.
 	 */
-	fd = fopen(cred->password_file, "r");
+	fd = fopen(cred->password_file, "re");
 	if (fd == NULL) {
 		gnutls_assert();
 		return GNUTLS_E_SRP_PWD_ERROR;
diff --git a/lib/auth/srp_passwd.c b/lib/auth/srp_passwd.c
index baa4086e77..78848cdf10 100644
--- a/lib/auth/srp_passwd.c
+++ b/lib/auth/srp_passwd.c
@@ -202,7 +202,7 @@ pwd_read_conf(const char *pconf_file, SRP_PWD_ENTRY * entry, int idx)
 
 	snprintf(indexstr, sizeof(indexstr), "%u", (unsigned int) idx);
 
-	fd = fopen(pconf_file, "r");
+	fd = fopen(pconf_file, "re");
 	if (fd == NULL) {
 		gnutls_assert();
 		return GNUTLS_E_FILE_ERROR;
@@ -308,7 +308,7 @@ _gnutls_srp_pwd_read_entry(gnutls_session_t state, char *username,
 
 	/* Open the selected password file.
 	 */
-	fd = fopen(cred->password_file, "r");
+	fd = fopen(cred->password_file, "re");
 	if (fd == NULL) {
 		gnutls_assert();
 		ret = GNUTLS_E_SRP_PWD_ERROR;
diff --git a/lib/file.c b/lib/file.c
index 2bcdee8b7e..03aa265c38 100644
--- a/lib/file.c
+++ b/lib/file.c
@@ -29,7 +29,7 @@ int _gnutls_file_exists(const char *file)
 {
 	FILE *fd;
 
-	fd = fopen(file, "r");
+	fd = fopen(file, "re");
 	if (fd == NULL)
 		return -1;
 
diff --git a/lib/fips.c b/lib/fips.c
index 3c43250aaf..0f0c34c1df 100644
--- a/lib/fips.c
+++ b/lib/fips.c
@@ -93,7 +93,7 @@ unsigned _gnutls_fips_mode_enabled(void)
 		goto exit;
 	}
 
-	fd = fopen(FIPS_KERNEL_FILE, "r");
+	fd = fopen(FIPS_KERNEL_FILE, "re");
 	if (fd != NULL) {
 		f1p = fgetc(fd);
 		fclose(fd);
diff --git a/lib/kx.c b/lib/kx.c
index a874f15114..1eda14d3d6 100644
--- a/lib/kx.c
+++ b/lib/kx.c
@@ -143,7 +143,7 @@ void _gnutls_nss_keylog_write(gnutls_session_t session,
 		checked_env = 1;
 		keylogfile = secure_getenv("SSLKEYLOGFILE");
 		if (keylogfile != NULL)
-			keylog = fopen(keylogfile, "a");
+			keylog = fopen(keylogfile, "ae");
 	}
 
 	if (keylog) {
diff --git a/lib/pkcs11.c b/lib/pkcs11.c
index d03bf6e444..fad16aaf4f 100644
--- a/lib/pkcs11.c
+++ b/lib/pkcs11.c
@@ -889,7 +889,7 @@ static void compat_load(const char *configfile)
 	if (configfile == NULL)
 		configfile = "/etc/gnutls/pkcs11.conf";
 
-	fp = fopen(configfile, "r");
+	fp = fopen(configfile, "re");
 	if (fp == NULL) {
 		gnutls_assert();
 		return;
diff --git a/lib/priority.c b/lib/priority.c
index ad99459adb..0a284ae1f1 100644
--- a/lib/priority.c
+++ b/lib/priority.c
@@ -1304,6 +1304,7 @@ static void _gnutls_update_system_priorities(void)
 {
 	int ret;
 	struct stat sb;
+	FILE *fp;
 
 	if (stat(system_priority_file, &sb) < 0) {
 		_gnutls_debug_log("cfg: unable to access: %s: %d\n",
@@ -1321,7 +1322,14 @@ static void _gnutls_update_system_priorities(void)
 	if (system_wide_priority_strings_init != 0)
 		_name_val_array_clear(&system_wide_priority_strings);
 
-	ret = ini_parse(system_priority_file, cfg_ini_handler, NULL);
+	fp = fopen(system_priority_file, "re");
+	if (fp == NULL) {
+		_gnutls_debug_log("cfg: unable to open: %s: %d\n",
+				  system_priority_file, errno);
+		return;
+	}
+	ret = ini_parse_file(fp, cfg_ini_handler, NULL);
+	fclose(fp);
 	if (ret != 0) {
 		_gnutls_debug_log("cfg: unable to parse: %s: %d\n",
 				  system_priority_file, ret);
diff --git a/lib/verify-tofu.c b/lib/verify-tofu.c
index 36328e04af..8baebaa011 100644
--- a/lib/verify-tofu.c
+++ b/lib/verify-tofu.c
@@ -343,7 +343,7 @@ static int verify_pubkey(const char *file,
 	if (service != NULL)
 		service_len = strlen(service);
 
-	fd = fopen(file, "rb");
+	fd = fopen(file, "rbe");
 	if (fd == NULL) {
 		ret = gnutls_assert_val(GNUTLS_E_FILE_ERROR);
 		goto cleanup;
@@ -414,7 +414,7 @@ int store_pubkey(const char *db_name, const char *host,
 		goto cleanup;
 	}
 
-	fd = fopen(db_name, "ab+");
+	fd = fopen(db_name, "abe+");
 	if (fd == NULL) {
 		ret = gnutls_assert_val(GNUTLS_E_FILE_ERROR);
 		goto cleanup;
@@ -449,7 +449,7 @@ int store_commitment(const char *db_name, const char *host,
 	FILE *fd;
 	char buffer[MAX_HASH_SIZE * 2 + 1];
 
-	fd = fopen(db_name, "ab+");
+	fd = fopen(db_name, "abe+");
 	if (fd == NULL)
 		return gnutls_assert_val(GNUTLS_E_FILE_ERROR);