tree-wide: whenever we deal with passwords, erase them from memory after use

A bit snake-oilish, but can't hurt.

8 files changed, 162 insertions, 84 deletions

diff --git a/src/ask-password/ask-password.c b/src/ask-password/ask-password.c
index 1a69d15908..89a49c2e86 100644
--- a/src/ask-password/ask-password.c
+++ b/src/ask-password/ask-password.c
@@ -174,6 +174,8 @@ int main(int argc, char *argv[]) {
                         break;
         }
 
+        strv_erase(l);
+
 finish:
         free(arg_message);
 
diff --git a/src/basic/util.c b/src/basic/util.c
index 2565b0f547..f24db9796e 100644
--- a/src/basic/util.c
+++ b/src/basic/util.c
@@ -6805,3 +6805,21 @@ bool fdname_is_valid(const char *s) {
 bool oom_score_adjust_is_valid(int oa) {
         return oa >= OOM_SCORE_ADJ_MIN && oa <= OOM_SCORE_ADJ_MAX;
 }
+
+void string_erase(char *x) {
+
+        if (!x)
+                return;
+
+        /* A delicious drop of snake-oil! To be called on memory where
+         * we stored passphrases or so, after we used them. */
+
+        memory_erase(x, strlen(x));
+}
+
+void strv_erase(char **l) {
+        char **i;
+
+        STRV_FOREACH(i, l)
+                string_erase(*i);
+}
diff --git a/src/basic/util.h b/src/basic/util.h
index 6c63bc221f..b1c64675e0 100644
--- a/src/basic/util.h
+++ b/src/basic/util.h
@@ -943,3 +943,7 @@ int version(void);
 bool fdname_is_valid(const char *s);
 
 bool oom_score_adjust_is_valid(int oa);
+
+#define memory_erase(p, l) memset((p), 'x', (l))
+void string_erase(char *x);
+void strv_erase(char **l);
diff --git a/src/cryptsetup/cryptsetup.c b/src/cryptsetup/cryptsetup.c
index cc03ad3ca8..c9be17446b 100644
--- a/src/cryptsetup/cryptsetup.c
+++ b/src/cryptsetup/cryptsetup.c
@@ -312,15 +312,16 @@ static char *disk_mount_point(const char *label) {
         return NULL;
 }
 
-static int get_password(const char *vol, const char *src, usec_t until, bool accept_cached, char ***passwords) {
+static int get_password(const char *vol, const char *src, usec_t until, bool accept_cached, char ***ret) {
         _cleanup_free_ char *description = NULL, *name_buffer = NULL, *mount_point = NULL, *maj_min = NULL, *text = NULL, *escaped_name = NULL;
+        _cleanup_strv_free_ char **passwords = NULL, **passwords2 = NULL;
         const char *name = NULL;
         char **p, *id;
         int r = 0;
 
         assert(vol);
         assert(src);
-        assert(passwords);
+        assert(ret);
 
         description = disk_description(src);
         mount_point = disk_mount_point(vol);
@@ -360,57 +361,74 @@ static int get_password(const char *vol, const char *src, usec_t until, bool acc
 
         id = strjoina("cryptsetup:", escaped_name);
 
-        r = ask_password_auto(text, "drive-harddisk", id, "cryptsetup", until, ASK_PASSWORD_PUSH_CACHE|(accept_cached ? ASK_PASSWORD_ACCEPT_CACHED : 0), passwords);
+        r = ask_password_auto(text, "drive-harddisk", id, "cryptsetup", until, ASK_PASSWORD_PUSH_CACHE|(accept_cached ? ASK_PASSWORD_ACCEPT_CACHED : 0), &passwords);
         if (r < 0)
                 return log_error_errno(r, "Failed to query password: %m");
 
         if (arg_verify) {
-                _cleanup_strv_free_ char **passwords2 = NULL;
+                assert(strv_length(passwords) == 1);
 
-                assert(strv_length(*passwords) == 1);
-
-                if (asprintf(&text, "Please enter passphrase for disk %s! (verification)", name) < 0)
-                        return log_oom();
+                if (asprintf(&text, "Please enter passphrase for disk %s! (verification)", name) < 0) {
+                        r = log_oom();
+                        goto finish;
+                }
 
                 id = strjoina("cryptsetup-verification:", escaped_name);
 
                 r = ask_password_auto(text, "drive-harddisk", id, "cryptsetup", until, ASK_PASSWORD_PUSH_CACHE, &passwords2);
-                if (r < 0)
-                        return log_error_errno(r, "Failed to query verification password: %m");
+                if (r < 0) {
+                        log_error_errno(r, "Failed to query verification password: %m");
+                        goto finish;
+                }
 
                 assert(strv_length(passwords2) == 1);
 
-                if (!streq(*passwords[0], passwords2[0])) {
+                if (!streq(passwords[0], passwords2[0])) {
                         log_warning("Passwords did not match, retrying.");
-                        return -EAGAIN;
+                        r = -EAGAIN;
+                        goto finish;
                 }
         }
 
-        strv_uniq(*passwords);
+        strv_uniq(passwords);
 
-        STRV_FOREACH(p, *passwords) {
+        STRV_FOREACH(p, passwords) {
                 char *c;
 
                 if (strlen(*p)+1 >= arg_key_size)
                         continue;
 
                 /* Pad password if necessary */
-                if (!(c = new(char, arg_key_size)))
-                        return log_oom();
+                c = new(char, arg_key_size);
+                if (!c) {
+                        r = -ENOMEM;
+                        goto finish;
+                }
 
                 strncpy(c, *p, arg_key_size);
                 free(*p);
                 *p = c;
         }
 
-        return 0;
+        *ret = passwords;
+        passwords = NULL;
+
+        r = 0;
+
+finish:
+        strv_erase(passwords);
+        strv_erase(passwords2);
+
+        return r;
 }
 
-static int attach_tcrypt(struct crypt_device *cd,
-                                const char *name,
-                                const char *key_file,
-                                char **passwords,
-                                uint32_t flags) {
+static int attach_tcrypt(
+                struct crypt_device *cd,
+                const char *name,
+                const char *key_file,
+                char **passwords,
+                uint32_t flags) {
+
         int r = 0;
         _cleanup_free_ char *passphrase = NULL;
         struct crypt_params_tcrypt params = {
@@ -520,8 +538,7 @@ static int attach_luks_or_plain(struct crypt_device *cd,
                  * it just configures encryption
                  * parameters when used for plain
                  * mode. */
-                r = crypt_format(cd, CRYPT_PLAIN, cipher, cipher_mode,
-                                 NULL, NULL, arg_keyfile_size, &params);
+                r = crypt_format(cd, CRYPT_PLAIN, cipher, cipher_mode, NULL, NULL, arg_keyfile_size, &params);
 
                 /* hash == NULL implies the user passed "plain" */
                 pass_volume_key = (params.hash == NULL);
@@ -537,9 +554,7 @@ static int attach_luks_or_plain(struct crypt_device *cd,
                  crypt_get_device_name(cd));
 
         if (key_file) {
-                r = crypt_activate_by_keyfile_offset(cd, name, arg_key_slot,
-                                                     key_file, arg_keyfile_size,
-                                                     arg_keyfile_offset, flags);
+                r = crypt_activate_by_keyfile_offset(cd, name, arg_key_slot, key_file, arg_keyfile_size, arg_keyfile_offset, flags);
                 if (r < 0) {
                         log_error_errno(r, "Failed to activate with key file '%s': %m", key_file);
                         return -EAGAIN;
@@ -631,7 +646,6 @@ int main(int argc, char *argv[]) {
                         k = crypt_init(&cd, arg_header);
                 } else
                         k = crypt_init(&cd, argv[3]);
-
                 if (k) {
                         log_error_errno(k, "crypt_init() failed: %m");
                         goto finish;
@@ -688,6 +702,7 @@ int main(int argc, char *argv[]) {
                                                          arg_header ? argv[3] : NULL,
                                                          passwords,
                                                          flags);
+                        strv_erase(passwords);
                         if (k >= 0)
                                 break;
                         else if (k == -EAGAIN) {
diff --git a/src/firstboot/firstboot.c b/src/firstboot/firstboot.c
index 1562ccf0d7..da247fbef8 100644
--- a/src/firstboot/firstboot.c
+++ b/src/firstboot/firstboot.c
@@ -51,15 +51,6 @@ static bool arg_copy_locale = false;
 static bool arg_copy_timezone = false;
 static bool arg_copy_root_password = false;
 
-static void clear_string(char *x) {
-
-        if (!x)
-                return;
-
-        /* A delicious drop of snake-oil! */
-        memset(x, 'x', strlen(x));
-}
-
 static bool press_any_key(void) {
         char k = 0;
         bool need_nl = true;
@@ -477,18 +468,18 @@ static int prompt_root_password(void) {
 
                 r = ask_password_tty(msg2, NULL, 0, 0, NULL, &b);
                 if (r < 0) {
-                        clear_string(a);
+                        string_erase(a);
                         return log_error_errno(r, "Failed to query root password: %m");
                 }
 
                 if (!streq(a, b)) {
                         log_error("Entered passwords did not match, please try again.");
-                        clear_string(a);
-                        clear_string(b);
+                        string_erase(a);
+                        string_erase(b);
                         continue;
                 }
 
-                clear_string(b);
+                string_erase(b);
                 arg_root_password = a;
                 a = NULL;
                 break;
@@ -881,7 +872,7 @@ finish:
         free(arg_locale_messages);
         free(arg_timezone);
         free(arg_hostname);
-        clear_string(arg_root_password);
+        string_erase(arg_root_password);
         free(arg_root_password);
 
         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
diff --git a/src/reply-password/reply-password.c b/src/reply-password/reply-password.c
index d0d61b98ed..534cf729b9 100644
--- a/src/reply-password/reply-password.c
+++ b/src/reply-password/reply-password.c
@@ -50,9 +50,10 @@ static int send_on_socket(int fd, const char *socket_name, const void *packet, s
 }
 
 int main(int argc, char *argv[]) {
-        int fd = -1, r = EXIT_FAILURE;
+        _cleanup_close_ int fd = -1;
         char packet[LINE_MAX];
         size_t length;
+        int r;
 
         log_set_target(LOG_TARGET_AUTO);
         log_parse_environment();
@@ -60,14 +61,14 @@ int main(int argc, char *argv[]) {
 
         if (argc != 3) {
                 log_error("Wrong number of arguments.");
-                goto finish;
+                return EXIT_FAILURE;
         }
 
         if (streq(argv[1], "1")) {
 
                 packet[0] = '+';
                 if (!fgets(packet+1, sizeof(packet)-1, stdin)) {
-                        log_error_errno(errno, "Failed to read password: %m");
+                        r = log_error_errno(errno, "Failed to read password: %m");
                         goto finish;
                 }
 
@@ -78,22 +79,20 @@ int main(int argc, char *argv[]) {
                 length = 1;
         } else {
                 log_error("Invalid first argument %s", argv[1]);
+                r = -EINVAL;
                 goto finish;
         }
 
         fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
         if (fd < 0) {
-                log_error_errno(errno, "socket() failed: %m");
+                r = log_error_errno(errno, "socket() failed: %m");
                 goto finish;
         }
 
-        if (send_on_socket(fd, argv[2], packet, length) < 0)
-                goto finish;
-
-        r = EXIT_SUCCESS;
+        r = send_on_socket(fd, argv[2], packet, length);
 
 finish:
-        safe_close(fd);
+        memory_erase(packet, sizeof(packet));
 
-        return r;
+        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 }
diff --git a/src/shared/ask-password-api.c b/src/shared/ask-password-api.c
index f8cf11b297..e35594a5df 100644
--- a/src/shared/ask-password-api.c
+++ b/src/shared/ask-password-api.c
@@ -78,6 +78,7 @@ static int retrieve_key(key_serial_t serial, char ***ret) {
                 if (n < m)
                         break;
 
+                memory_erase(p, n);
                 free(p);
                 m *= 2;
         }
@@ -86,6 +87,8 @@ static int retrieve_key(key_serial_t serial, char ***ret) {
         if (!l)
                 return -ENOMEM;
 
+        memory_erase(p, n);
+
         *ret = l;
         return 0;
 }
@@ -116,6 +119,7 @@ static int add_to_keyring(const char *keyname, AskPasswordFlags flags, char **pa
                 return r;
 
         r = strv_make_nulstr(l, &p, &n);
+        strv_erase(l);
         if (r < 0)
                 return r;
 
@@ -124,6 +128,7 @@ static int add_to_keyring(const char *keyname, AskPasswordFlags flags, char **pa
         assert(p[n-1] == 0);
 
         serial = add_key("user", keyname, p, n-1, KEY_SPEC_USER_KEYRING);
+        memory_erase(p, n);
         if (serial == -1)
                 return -errno;
 
@@ -361,9 +366,12 @@ int ask_password_tty(
 
                         dirty = true;
                 }
+
+                c = 'x';
         }
 
         x = strndup(passphrase, p);
+        memory_erase(passphrase, p);
         if (!x) {
                 r = -ENOMEM;
                 goto finish;
@@ -620,6 +628,7 @@ int ask_password_agent(
                                 l = strv_new("", NULL);
                         else
                                 l = strv_parse_nulstr(passphrase+1, n-1);
+                        memory_erase(passphrase, n);
                         if (!l) {
                                 r = -ENOMEM;
                                 goto finish;
@@ -688,9 +697,12 @@ int ask_password_auto(
                 if (r < 0)
                         return r;
 
-                r = strv_consume(&l, s);
-                if (r < 0)
+                r = strv_push(&l, s);
+                if (r < 0) {
+                        string_erase(s);
+                        free(s);
                         return -ENOMEM;
+                }
 
                 *ret = l;
                 return 0;
diff --git a/src/tty-ask-password-agent/tty-ask-password-agent.c b/src/tty-ask-password-agent/tty-ask-password-agent.c
index 53986babae..7a5ac9fa9c 100644
--- a/src/tty-ask-password-agent/tty-ask-password-agent.c
+++ b/src/tty-ask-password-agent/tty-ask-password-agent.c
@@ -120,23 +120,30 @@ static int ask_password_plymouth(
 
                         y = now(CLOCK_MONOTONIC);
 
-                        if (y > until)
-                                return -ETIME;
+                        if (y > until) {
+                                r = -ETIME;
+                                goto finish;
+                        }
 
                         sleep_for = (int) ((until - y) / USEC_PER_MSEC);
                 }
 
-                if (flag_file && access(flag_file, F_OK) < 0)
-                        return -errno;
+                if (flag_file && access(flag_file, F_OK) < 0) {
+                        r = -errno;
+                        goto finish;
+                }
 
                 j = poll(pollfd, notify >= 0 ? 2 : 1, sleep_for);
                 if (j < 0) {
                         if (errno == EINTR)
                                 continue;
 
-                        return -errno;
-                } else if (j == 0)
-                        return -ETIME;
+                        r = -errno;
+                        goto finish;
+                } else if (j == 0) {
+                        r = -ETIME;
+                        goto finish;
+                }
 
                 if (notify >= 0 && pollfd[POLL_INOTIFY].revents != 0)
                         flush_fd(notify);
@@ -149,9 +156,12 @@ static int ask_password_plymouth(
                         if (errno == EINTR || errno == EAGAIN)
                                 continue;
 
-                        return -errno;
-                } else if (k == 0)
-                        return -EIO;
+                        r = -errno;
+                        goto finish;
+                } else if (k == 0) {
+                        r = -EIO;
+                        goto finish;
+                }
 
                 p += k;
 
@@ -166,12 +176,14 @@ static int ask_password_plymouth(
                                  * with a normal password request */
                                 packet = mfree(packet);
 
-                                if (asprintf(&packet, "*\002%c%s%n", (int) (strlen(message) + 1), message, &n) < 0)
-                                        return -ENOMEM;
+                                if (asprintf(&packet, "*\002%c%s%n", (int) (strlen(message) + 1), message, &n) < 0) {
+                                        r = -ENOMEM;
+                                        goto finish;
+                                }
 
                                 r = loop_write(fd, packet, n+1, true);
                                 if (r < 0)
-                                        return r;
+                                        goto finish;
 
                                 flags &= ~ASK_PASSWORD_ACCEPT_CACHED;
                                 p = 0;
@@ -179,7 +191,8 @@ static int ask_password_plymouth(
                         }
 
                         /* No password, because UI not shown */
-                        return -ENOENT;
+                        r = -ENOENT;
+                        goto finish;
 
                 } else if (buffer[0] == 2 || buffer[0] == 9) {
                         uint32_t size;
@@ -191,32 +204,43 @@ static int ask_password_plymouth(
 
                         memcpy(&size, buffer+1, sizeof(size));
                         size = le32toh(size);
-                        if (size + 5 > sizeof(buffer))
-                                return -EIO;
+                        if (size + 5 > sizeof(buffer)) {
+                                r = -EIO;
+                                goto finish;
+                        }
 
                         if (p-5 < size)
                                 continue;
 
                         l = strv_parse_nulstr(buffer + 5, size);
-                        if (!l)
-                                return -ENOMEM;
+                        if (!l) {
+                                r = -ENOMEM;
+                                goto finish;
+                        }
 
                         *ret = l;
                         break;
 
-                } else
+                } else {
                         /* Unknown packet */
-                        return -EIO;
+                        r = -EIO;
+                        goto finish;
+                }
         }
 
-        return 0;
+        r = 0;
+
+finish:
+        memory_erase(buffer, sizeof(buffer));
+        return r;
 }
 
 static int parse_password(const char *filename, char **wall) {
         _cleanup_free_ char *socket_name = NULL, *message = NULL, *packet = NULL;
+        bool accept_cached = false, echo = false;
+        size_t packet_length = 0;
         uint64_t not_after = 0;
         unsigned pid = 0;
-        bool accept_cached = false, echo = false;
 
         const ConfigTableItem items[] = {
                 { "Ask", "Socket",       config_parse_string,   0, &socket_name   },
@@ -270,7 +294,6 @@ static int parse_password(const char *filename, char **wall) {
 
         } else {
                 union sockaddr_union sa = {};
-                size_t packet_length = 0;
                 _cleanup_close_ int socket_fd = -1;
 
                 assert(arg_action == ACTION_QUERY ||
@@ -307,6 +330,8 @@ static int parse_password(const char *filename, char **wall) {
                                 }
                         }
 
+                        strv_erase(passwords);
+
                 } else {
                         _cleanup_free_ char *password = NULL;
                         int tty_fd = -1;
@@ -338,28 +363,40 @@ static int parse_password(const char *filename, char **wall) {
                                         strcpy(packet + 1, password);
                                 }
                         }
+
+                        string_erase(password);
                 }
 
-                if (IN_SET(r, -ETIME, -ENOENT))
+                if (IN_SET(r, -ETIME, -ENOENT)) {
                         /* If the query went away, that's OK */
-                        return 0;
-
-                if (r < 0)
-                        return log_error_errno(r, "Failed to query password: %m");
+                        r = 0;
+                        goto finish;
+                }
+                if (r < 0) {
+                        log_error_errno(r, "Failed to query password: %m");
+                        goto finish;
+                }
 
                 socket_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0);
-                if (socket_fd < 0)
-                        return log_error_errno(errno, "socket(): %m");
+                if (socket_fd < 0) {
+                        r = log_error_errno(errno, "socket(): %m");
+                        goto finish;
+                }
 
                 sa.un.sun_family = AF_UNIX;
                 strncpy(sa.un.sun_path, socket_name, sizeof(sa.un.sun_path));
 
                 r = sendto(socket_fd, packet, packet_length, MSG_NOSIGNAL, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(socket_name));
+                memory_erase(packet, packet_length);
                 if (r < 0)
                         return log_error_errno(errno, "Failed to send: %m");
         }
 
         return 0;
+
+finish:
+        memory_erase(packet, packet_length);
+        return r;
 }
 
 static int wall_tty_block(void) {