Fix misuse of PAM_PROMPT_ECHO_OFF in systemd-homed

Previously pam_systemd_home.so was relying on `PAM_PROMPT_ECHO_OFF` to
display error messages to the user and also display the next prompt.
`PAM_PROMPT_ECHO_OFF` was never meant as a way to convey information to
the user, and following the example set in pam_unix.so you can see that
it's meant to _only_ display the prompt. Details about why the
authentication failed should be done in a `PAM_ERROR_MSG` before
displaying a short prompt as per usual using `PAM_PROMPT_ECHO_OFF`.

meson.build

@@ -411,6 +411,9 @@ add_project_arguments(cc.get_supported_arguments(basic_disabled_warnings), langu
 add_project_arguments(cc.get_supported_arguments(possible_cc_flags), language : 'c')
 add_project_link_arguments(cc.get_supported_link_arguments(possible_link_flags), language : 'c')
 
+have = cc.has_argument('-Wzero-length-bounds')
+conf.set10('HAVE_ZERO_LENGTH_BOUNDS', have)
+
 if cc.compiles('''
    #include <time.h>
    #include <inttypes.h>

src/core/path.c

@@ -223,11 +223,10 @@ static void path_spec_mkdir(PathSpec *s, mode_t mode) {
 }
 
 static void path_spec_dump(PathSpec *s, FILE *f, const char *prefix) {
-        fprintf(f,
+        const char *type;
-                "%s%s: %s\n",
+
-                prefix,
+        assert_se(type = path_type_to_string(s->type));
-                path_type_to_string(s->type),
+        fprintf(f, "%s%s: %s\n", prefix, type, s->path);
-                s->path);
 }
 
 void path_spec_done(PathSpec *s) {
@@ -607,14 +606,16 @@ static int path_serialize(Unit *u, FILE *f, FDSet *fds) {
         (void) serialize_item(f, "result", path_result_to_string(p->result));
 
         LIST_FOREACH(spec, s, p->specs) {
+                const char *type;
                 _cleanup_free_ char *escaped = NULL;
 
                 escaped = cescape(s->path);
                 if (!escaped)
                         return log_oom();
 
+                assert_se(type = path_type_to_string(s->type));
                 (void) serialize_item_format(f, "path-spec", "%s %i %s",
-                                             path_type_to_string(s->type),
+                                             type,
                                              s->previous_exists,
                                              s->path);
         }

src/home/pam_systemd_home.c

@@ -250,8 +250,10 @@ static int handle_generic_user_record_error(
 
                 if (strv_isempty(secret->password))
                         r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Password: ");
-                else
+                else {
-                        r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Password incorrect or not sufficient for authentication of user %s, please try again: ", user_name);
+                        (void) pam_prompt(handle, PAM_ERROR_MSG, NULL, "Password incorrect or not sufficient for authentication of user %s.", user_name);
+                        r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Sorry, try again: ");
+                }
                 if (r != PAM_SUCCESS)
                         return PAM_CONV_ERR; /* no logging here */
 
@@ -269,10 +271,13 @@ static int handle_generic_user_record_error(
         } else if (sd_bus_error_has_name(error, BUS_ERROR_BAD_PASSWORD_AND_NO_TOKEN)) {
                 _cleanup_(erase_and_freep) char *newp = NULL;
 
-                if (strv_isempty(secret->password))
+                if (strv_isempty(secret->password)) {
-                        r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Security token of user %s not inserted, please enter password: ", user_name);
+                        (void) pam_prompt(handle, PAM_ERROR_MSG, NULL, "Security token of user %s not inserted.", user_name);
-                else
+                        r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Try again with password: ");
-                        r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Password incorrect or not sufficient, and configured security token of user %s not inserted, please enter password: ", user_name);
+                } else {
+                        (void) pam_prompt(handle, PAM_ERROR_MSG, NULL, "Password incorrect or not sufficient, and configured security token of user %s not inserted.", user_name);
+                        r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Try again with password: ");
+                }
                 if (r != PAM_SUCCESS)
                         return PAM_CONV_ERR; /* no logging here */
 
@@ -290,7 +295,7 @@ static int handle_generic_user_record_error(
         } else if (sd_bus_error_has_name(error, BUS_ERROR_TOKEN_PIN_NEEDED)) {
                 _cleanup_(erase_and_freep) char *newp = NULL;
 
-                r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Please enter security token PIN: ");
+                r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Security token PIN: ");
                 if (r != PAM_SUCCESS)
                         return PAM_CONV_ERR; /* no logging here */
 
@@ -318,7 +323,8 @@ static int handle_generic_user_record_error(
         } else if (sd_bus_error_has_name(error, BUS_ERROR_TOKEN_BAD_PIN)) {
                 _cleanup_(erase_and_freep) char *newp = NULL;
 
-                r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Security token PIN incorrect, please enter PIN for security token of user %s again: ", user_name);
+                (void) pam_prompt(handle, PAM_ERROR_MSG, NULL, "Security token PIN incorrect for user %s.", user_name);
+                r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Sorry, retry security token PIN: ");
                 if (r != PAM_SUCCESS)
                         return PAM_CONV_ERR; /* no logging here */
 
@@ -336,7 +342,8 @@ static int handle_generic_user_record_error(
         } else if (sd_bus_error_has_name(error, BUS_ERROR_TOKEN_BAD_PIN_FEW_TRIES_LEFT)) {
                 _cleanup_(erase_and_freep) char *newp = NULL;
 
-                r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Security token PIN incorrect (only a few tries left!), please enter PIN for security token of user %s again: ", user_name);
+                (void) pam_prompt(handle, PAM_ERROR_MSG, NULL, "Security token PIN of user %s incorrect (only a few tries left!)", user_name);
+                r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Sorry, retry security token PIN: ");
                 if (r != PAM_SUCCESS)
                         return PAM_CONV_ERR; /* no logging here */
 
@@ -354,7 +361,8 @@ static int handle_generic_user_record_error(
         } else if (sd_bus_error_has_name(error, BUS_ERROR_TOKEN_BAD_PIN_ONE_TRY_LEFT)) {
                 _cleanup_(erase_and_freep) char *newp = NULL;
 
-                r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Security token PIN incorrect (only one try left!), please enter PIN for security token of user %s again: ", user_name);
+                (void) pam_prompt(handle, PAM_ERROR_MSG, NULL, "Security token PIN of user %s incorrect (only one try left!)", user_name);
+                r = pam_prompt(handle, PAM_PROMPT_ECHO_OFF, &newp, "Sorry, retry security token PIN: ");
                 if (r != PAM_SUCCESS)
                         return PAM_CONV_ERR; /* no logging here */
 

src/shared/ethtool-util.c

@@ -256,8 +256,13 @@ int ethtool_get_permanent_macaddr(int *ethtool_fd, const char *ifname, struct et
         if (epaddr.addr.size != 6)
                 return -EOPNOTSUPP;
 
+#pragma GCC diagnostic push
+#if HAVE_ZERO_LENGTH_BOUNDS
+#  pragma GCC diagnostic ignored "-Wzero-length-bounds"
+#endif
         for (size_t i = 0; i < epaddr.addr.size; i++)
                 ret->ether_addr_octet[i] = epaddr.addr.data[i];
+#pragma GCC diagnostic pop
 
         return 0;
 }
@@ -485,7 +490,12 @@ static int get_stringset(int ethtool_fd, struct ifreq *ifr, int stringset_id, st
         if (!buffer.info.sset_mask)
                 return -EINVAL;
 
+#pragma GCC diagnostic push
+#if HAVE_ZERO_LENGTH_BOUNDS
+#  pragma GCC diagnostic ignored "-Wzero-length-bounds"
+#endif
         len = buffer.info.data[0];
+#pragma GCC diagnostic pop
 
         strings = malloc0(sizeof(struct ethtool_gstrings) + len * ETH_GSTRING_LEN);
         if (!strings)