1 files changed, 57 insertions, 0 deletions
diff --git a/src/home/homework-password-cache.c b/src/home/homework-password-cache.c
new file mode 100644
index 0000000..00a0f69
--- /dev/null
+++ b/src/home/homework-password-cache.c
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "homework-password-cache.h"
+#include "keyring-util.h"
+#include "missing_syscall.h"
+#include "user-record.h"
+
+void password_cache_free(PasswordCache *cache) {
+        if (!cache)
+                return;
+
+        cache->pkcs11_passwords = strv_free_erase(cache->pkcs11_passwords);
+        cache->fido2_passwords = strv_free_erase(cache->fido2_passwords);
+        cache->keyring_passswords = strv_free_erase(cache->keyring_passswords);
+}
+
+void password_cache_load_keyring(UserRecord *h, PasswordCache *cache) {
+        _cleanup_(erase_and_freep) void *p = NULL;
+        _cleanup_free_ char *name = NULL;
+        char **strv;
+        key_serial_t serial;
+        size_t sz;
+        int r;
+
+        assert(h);
+        assert(cache);
+
+        /* Loads the password we need to for automatic resizing from the kernel keyring */
+
+        name = strjoin("homework-user-", h->user_name);
+        if (!name)
+                return (void) log_oom();
+
+        serial = request_key("user", name, NULL, 0);
+        if (serial == -1)
+                return (void) log_debug_errno(errno, "Failed to request key '%s', ignoring: %m", name);
+
+        r = keyring_read(serial, &p, &sz);
+        if (r < 0)
+                return (void) log_debug_errno(r, "Failed to read keyring key '%s', ignoring: %m", name);
+
+        if (memchr(p, 0, sz))
+                return (void) log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Cached password contains embedded NUL byte, ignoring.");
+
+        strv = new(char*, 2);
+        if (!strv)
+                return (void) log_oom();
+
+        strv[0] = TAKE_PTR(p); /* Note that keyring_read() will NUL terminate implicitly, hence we don't have
+                                * to NUL terminate manually here: it's a valid string. */
+        strv[1] = NULL;
+
+        strv_free_erase(cache->keyring_passswords);
+        cache->keyring_passswords = strv;
+
+        log_debug("Successfully acquired home key from kernel keyring.");
+}