1 files changed, 110 insertions, 0 deletions
diff --git a/src/cryptsetup/cryptsetup-keyfile.c b/src/cryptsetup/cryptsetup-keyfile.c
new file mode 100644
index 0000000..f849123
--- /dev/null
+++ b/src/cryptsetup/cryptsetup-keyfile.c
@@ -0,0 +1,110 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <unistd.h>
+
+#include "cryptsetup-keyfile.h"
+#include "fd-util.h"
+#include "format-util.h"
+#include "memory-util.h"
+#include "path-util.h"
+#include "stat-util.h"
+#include "strv.h"
+
+#define KEY_FILE_SIZE_MAX (16U*1024U*1024U) /* 16 MiB */
+
+int load_key_file(
+                const char *key_file,
+                char **search_path,
+                size_t key_file_size,
+                uint64_t key_file_offset,
+                void **ret_key,
+                size_t *ret_key_size) {
+
+        _cleanup_(erase_and_freep) char *buffer = NULL;
+        _cleanup_free_ char *discovered_path = NULL;
+        _cleanup_close_ int fd = -1;
+        ssize_t n;
+        int r;
+
+        assert(key_file);
+        assert(ret_key);
+        assert(ret_key_size);
+
+        if (strv_isempty(search_path) || path_is_absolute(key_file)) {
+                fd = open(key_file, O_RDONLY|O_CLOEXEC);
+                if (fd < 0)
+                        return log_error_errno(errno, "Failed to load key file '%s': %m", key_file);
+        } else {
+                char **i;
+
+                STRV_FOREACH(i, search_path) {
+                        _cleanup_free_ char *joined;
+
+                        joined = path_join(*i, key_file);
+                        if (!joined)
+                                return log_oom();
+
+                        fd = open(joined, O_RDONLY|O_CLOEXEC);
+                        if (fd >= 0) {
+                                discovered_path = TAKE_PTR(joined);
+                                break;
+                        }
+                        if (errno != ENOENT)
+                                return log_error_errno(errno, "Failed to load key file '%s': %m", joined);
+                }
+
+                if (!discovered_path) {
+                        /* Search path supplied, but file not found, report by returning NULL, but not failing */
+                        *ret_key = NULL;
+                        *ret_key_size = 0;
+                        return 0;
+                }
+
+                assert(fd >= 0);
+                key_file = discovered_path;
+        }
+
+        if (key_file_size == 0) {
+                struct stat st;
+
+                if (fstat(fd, &st) < 0)
+                        return log_error_errno(errno, "Failed to stat key file '%s': %m", key_file);
+
+                r = stat_verify_regular(&st);
+                if (r < 0)
+                        return log_error_errno(r, "Key file is not a regular file: %m");
+
+                if (st.st_size == 0)
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Key file is empty, refusing.");
+                if ((uint64_t) st.st_size > KEY_FILE_SIZE_MAX) {
+                        char buf1[FORMAT_BYTES_MAX], buf2[FORMAT_BYTES_MAX];
+                        return log_error_errno(SYNTHETIC_ERRNO(ERANGE),
+                                               "Key file larger (%s) than allowed maximum size (%s), refusing.",
+                                               format_bytes(buf1, sizeof(buf1), st.st_size),
+                                               format_bytes(buf2, sizeof(buf2), KEY_FILE_SIZE_MAX));
+                }
+
+                if (key_file_offset >= (uint64_t) st.st_size)
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Key file offset too large for file, refusing.");
+
+                key_file_size = st.st_size - key_file_offset;
+        }
+
+        buffer = malloc(key_file_size);
+        if (!buffer)
+                return log_oom();
+
+        if (key_file_offset > 0)
+                n = pread(fd, buffer, key_file_size, key_file_offset);
+        else
+                n = read(fd, buffer, key_file_size);
+        if (n < 0)
+                return log_error_errno(errno, "Failed to read key file '%s': %m", key_file);
+        if (n == 0)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Empty encrypted key found, refusing.");
+
+        *ret_key = TAKE_PTR(buffer);
+        *ret_key_size = (size_t) n;
+
+        return 1;
+}