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-rw-r--r--src/boot/efi/cpio.c568
1 files changed, 568 insertions, 0 deletions
diff --git a/src/boot/efi/cpio.c b/src/boot/efi/cpio.c
new file mode 100644
index 0000000..79b5d43
--- /dev/null
+++ b/src/boot/efi/cpio.c
@@ -0,0 +1,568 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "cpio.h"
+#include "measure.h"
+#include "util.h"
+
+static char *write_cpio_word(char *p, uint32_t v) {
+ static const char hex[] = "0123456789abcdef";
+
+ assert(p);
+
+ /* Writes a CPIO header 8 character hex value */
+
+ for (UINTN i = 0; i < 8; i++)
+ p[7-i] = hex[(v >> (4 * i)) & 0xF];
+
+ return p + 8;
+}
+
+static char *mangle_filename(char *p, const char16_t *f) {
+ char* w;
+
+ assert(p);
+ assert(f);
+
+ /* Basically converts UTF-16 to plain ASCII (note that we filtered non-ASCII filenames beforehand, so
+ * this operation is always safe) */
+
+ for (w = p; *f != 0; f++) {
+ assert(*f <= 0x7fu);
+
+ *(w++) = *f;
+ }
+
+ *(w++) = 0;
+ return w;
+}
+
+static char *pad4(char *p, const char *start) {
+ assert(p);
+ assert(start);
+ assert(p >= start);
+
+ /* Appends NUL bytes to 'p', until the address is divisible by 4, when taken relative to 'start' */
+
+ while ((p - start) % 4 != 0)
+ *(p++) = 0;
+
+ return p;
+}
+
+static EFI_STATUS pack_cpio_one(
+ const char16_t *fname,
+ const void *contents,
+ UINTN contents_size,
+ const char *target_dir_prefix,
+ uint32_t access_mode,
+ uint32_t *inode_counter,
+ void **cpio_buffer,
+ UINTN *cpio_buffer_size) {
+
+ UINTN l, target_dir_prefix_size, fname_size, q;
+ char *a;
+
+ assert(fname);
+ assert(contents_size || contents_size == 0);
+ assert(target_dir_prefix);
+ assert(inode_counter);
+ assert(cpio_buffer);
+ assert(cpio_buffer_size);
+
+ /* Serializes one file in the cpio format understood by the kernel initrd logic.
+ *
+ * See: https://docs.kernel.org/driver-api/early-userspace/buffer-format.html */
+
+ if (contents_size > UINT32_MAX) /* cpio cannot deal with > 32bit file sizes */
+ return EFI_LOAD_ERROR;
+
+ if (*inode_counter == UINT32_MAX) /* more than 2^32-1 inodes? yikes. cpio doesn't support that either */
+ return EFI_OUT_OF_RESOURCES;
+
+ l = 6 + 13*8 + 1 + 1; /* Fixed CPIO header size, slash separator, and NUL byte after the file name*/
+
+ target_dir_prefix_size = strlen8(target_dir_prefix);
+ if (l > UINTN_MAX - target_dir_prefix_size)
+ return EFI_OUT_OF_RESOURCES;
+ l += target_dir_prefix_size;
+
+ fname_size = strlen16(fname);
+ if (l > UINTN_MAX - fname_size)
+ return EFI_OUT_OF_RESOURCES;
+ l += fname_size; /* append space for file name */
+
+ /* CPIO can't deal with fnames longer than 2^32-1 */
+ if (target_dir_prefix_size + fname_size >= UINT32_MAX)
+ return EFI_OUT_OF_RESOURCES;
+
+ /* Align the whole header to 4 byte size */
+ l = ALIGN4(l);
+ if (l == UINTN_MAX) /* overflow check */
+ return EFI_OUT_OF_RESOURCES;
+
+ /* Align the contents to 4 byte size */
+ q = ALIGN4(contents_size);
+ if (q == UINTN_MAX) /* overflow check */
+ return EFI_OUT_OF_RESOURCES;
+
+ if (l > UINTN_MAX - q) /* overflow check */
+ return EFI_OUT_OF_RESOURCES;
+ l += q; /* Add contents to header */
+
+ if (*cpio_buffer_size > UINTN_MAX - l) /* overflow check */
+ return EFI_OUT_OF_RESOURCES;
+ a = xrealloc(*cpio_buffer, *cpio_buffer_size, *cpio_buffer_size + l);
+
+ *cpio_buffer = a;
+ a = (char *) *cpio_buffer + *cpio_buffer_size;
+
+ a = mempcpy(a, "070701", 6); /* magic ID */
+
+ a = write_cpio_word(a, (*inode_counter)++); /* inode */
+ a = write_cpio_word(a, access_mode | 0100000 /* = S_IFREG */); /* mode */
+ a = write_cpio_word(a, 0); /* uid */
+ a = write_cpio_word(a, 0); /* gid */
+ a = write_cpio_word(a, 1); /* nlink */
+
+ /* Note: we don't make any attempt to propagate the mtime here, for two reasons: it's a mess given
+ * that FAT usually is assumed to operate with timezoned timestamps, while UNIX does not. More
+ * importantly though: the modifications times would hamper our goals of providing stable
+ * measurements for the same boots. After all we extend the initrds we generate here into TPM2
+ * PCRs. */
+ a = write_cpio_word(a, 0); /* mtime */
+ a = write_cpio_word(a, contents_size); /* size */
+ a = write_cpio_word(a, 0); /* major(dev) */
+ a = write_cpio_word(a, 0); /* minor(dev) */
+ a = write_cpio_word(a, 0); /* major(rdev) */
+ a = write_cpio_word(a, 0); /* minor(rdev) */
+ a = write_cpio_word(a, target_dir_prefix_size + fname_size + 2); /* fname size */
+ a = write_cpio_word(a, 0); /* "crc" */
+
+ a = mempcpy(a, target_dir_prefix, target_dir_prefix_size);
+ *(a++) = '/';
+ a = mangle_filename(a, fname);
+
+ /* Pad to next multiple of 4 */
+ a = pad4(a, *cpio_buffer);
+
+ a = mempcpy(a, contents, contents_size);
+
+ /* Pad to next multiple of 4 */
+ a = pad4(a, *cpio_buffer);
+
+ assert(a == (char *) *cpio_buffer + *cpio_buffer_size + l);
+ *cpio_buffer_size += l;
+
+ return EFI_SUCCESS;
+}
+
+static EFI_STATUS pack_cpio_dir(
+ const char *path,
+ uint32_t access_mode,
+ uint32_t *inode_counter,
+ void **cpio_buffer,
+ UINTN *cpio_buffer_size) {
+
+ UINTN l, path_size;
+ char *a;
+
+ assert(path);
+ assert(inode_counter);
+ assert(cpio_buffer);
+ assert(cpio_buffer_size);
+
+ /* Serializes one directory inode in cpio format. Note that cpio archives must first create the dirs
+ * they want to place files in. */
+
+ if (*inode_counter == UINT32_MAX)
+ return EFI_OUT_OF_RESOURCES;
+
+ l = 6 + 13*8 + 1; /* Fixed CPIO header size, and NUL byte after the file name*/
+
+ path_size = strlen8(path);
+ if (l > UINTN_MAX - path_size)
+ return EFI_OUT_OF_RESOURCES;
+ l += path_size;
+
+ /* Align the whole header to 4 byte size */
+ l = ALIGN4(l);
+ if (l == UINTN_MAX) /* overflow check */
+ return EFI_OUT_OF_RESOURCES;
+
+ if (*cpio_buffer_size > UINTN_MAX - l) /* overflow check */
+ return EFI_OUT_OF_RESOURCES;
+
+ *cpio_buffer = a = xrealloc(*cpio_buffer, *cpio_buffer_size, *cpio_buffer_size + l);
+ a = (char *) *cpio_buffer + *cpio_buffer_size;
+
+ a = mempcpy(a, "070701", 6); /* magic ID */
+
+ a = write_cpio_word(a, (*inode_counter)++); /* inode */
+ a = write_cpio_word(a, access_mode | 0040000 /* = S_IFDIR */); /* mode */
+ a = write_cpio_word(a, 0); /* uid */
+ a = write_cpio_word(a, 0); /* gid */
+ a = write_cpio_word(a, 1); /* nlink */
+ a = write_cpio_word(a, 0); /* mtime */
+ a = write_cpio_word(a, 0); /* size */
+ a = write_cpio_word(a, 0); /* major(dev) */
+ a = write_cpio_word(a, 0); /* minor(dev) */
+ a = write_cpio_word(a, 0); /* major(rdev) */
+ a = write_cpio_word(a, 0); /* minor(rdev) */
+ a = write_cpio_word(a, path_size + 1); /* fname size */
+ a = write_cpio_word(a, 0); /* "crc" */
+
+ a = mempcpy(a, path, path_size + 1);
+
+ /* Pad to next multiple of 4 */
+ a = pad4(a, *cpio_buffer);
+
+ assert(a == (char *) *cpio_buffer + *cpio_buffer_size + l);
+
+ *cpio_buffer_size += l;
+ return EFI_SUCCESS;
+}
+
+static EFI_STATUS pack_cpio_prefix(
+ const char *path,
+ uint32_t dir_mode,
+ uint32_t *inode_counter,
+ void **cpio_buffer,
+ UINTN *cpio_buffer_size) {
+
+ EFI_STATUS err;
+
+ assert(path);
+ assert(inode_counter);
+ assert(cpio_buffer);
+ assert(cpio_buffer_size);
+
+ /* Serializes directory inodes of all prefix paths of the specified path in cpio format. Note that
+ * (similar to mkdir -p behaviour) all leading paths are created with 0555 access mode, only the
+ * final dir is created with the specified directory access mode. */
+
+ for (const char *p = path;;) {
+ const char *e;
+
+ e = strchr8(p, '/');
+ if (!e)
+ break;
+
+ if (e > p) {
+ _cleanup_free_ char *t = NULL;
+
+ t = xstrndup8(path, e - path);
+ if (!t)
+ return EFI_OUT_OF_RESOURCES;
+
+ err = pack_cpio_dir(t, 0555, inode_counter, cpio_buffer, cpio_buffer_size);
+ if (err != EFI_SUCCESS)
+ return err;
+ }
+
+ p = e + 1;
+ }
+
+ return pack_cpio_dir(path, dir_mode, inode_counter, cpio_buffer, cpio_buffer_size);
+}
+
+static EFI_STATUS pack_cpio_trailer(
+ void **cpio_buffer,
+ UINTN *cpio_buffer_size) {
+
+ static const char trailer[] =
+ "070701"
+ "00000000"
+ "00000000"
+ "00000000"
+ "00000000"
+ "00000001"
+ "00000000"
+ "00000000"
+ "00000000"
+ "00000000"
+ "00000000"
+ "00000000"
+ "0000000B"
+ "00000000"
+ "TRAILER!!!\0\0\0"; /* There's a fourth NUL byte appended here, because this is a string */
+
+ /* Generates the cpio trailer record that indicates the end of our initrd cpio archive */
+
+ assert(cpio_buffer);
+ assert(cpio_buffer_size);
+ assert_cc(sizeof(trailer) % 4 == 0);
+
+ *cpio_buffer = xrealloc(*cpio_buffer, *cpio_buffer_size, *cpio_buffer_size + sizeof(trailer));
+ memcpy((uint8_t*) *cpio_buffer + *cpio_buffer_size, trailer, sizeof(trailer));
+ *cpio_buffer_size += sizeof(trailer);
+
+ return EFI_SUCCESS;
+}
+
+static EFI_STATUS measure_cpio(
+ void *buffer,
+ UINTN buffer_size,
+ const uint32_t tpm_pcr[],
+ UINTN n_tpm_pcr,
+ const char16_t *tpm_description,
+ bool *ret_measured) {
+
+ int measured = -1;
+ EFI_STATUS err;
+
+ assert(buffer || buffer_size == 0);
+ assert(tpm_pcr || n_tpm_pcr == 0);
+
+ for (UINTN i = 0; i < n_tpm_pcr; i++) {
+ bool m;
+
+ if (tpm_pcr[i] == UINT32_MAX) /* Disabled */
+ continue;
+
+ err = tpm_log_event(
+ tpm_pcr[i],
+ POINTER_TO_PHYSICAL_ADDRESS(buffer),
+ buffer_size,
+ tpm_description,
+ &m);
+ if (err != EFI_SUCCESS) {
+ log_error_stall(L"Unable to add initrd TPM measurement for PCR %u (%s), ignoring: %r", tpm_pcr[i], tpm_description, err);
+ measured = false;
+ continue;
+ }
+
+ if (measured != false)
+ measured = m;
+ }
+
+ if (ret_measured)
+ *ret_measured = measured > 0;
+
+ return EFI_SUCCESS;
+}
+
+static char16_t *get_dropin_dir(const EFI_DEVICE_PATH *file_path) {
+ if (!file_path)
+ return NULL;
+
+ /* A device path is allowed to have more than one file path node. If that is the case they are
+ * supposed to be concatenated. Unfortunately, the device path to text protocol simply converts the
+ * nodes individually and then combines those with the usual '/' for device path nodes. But this does
+ * not create a legal EFI file path that the file protocol can use. */
+
+ /* Make sure we really only got file paths. */
+ for (const EFI_DEVICE_PATH *node = file_path; !IsDevicePathEnd(node); node = NextDevicePathNode(node))
+ if (DevicePathType(node) != MEDIA_DEVICE_PATH || DevicePathSubType(node) != MEDIA_FILEPATH_DP)
+ return NULL;
+
+ _cleanup_free_ char16_t *file_path_str = NULL;
+ if (device_path_to_str(file_path, &file_path_str) != EFI_SUCCESS)
+ return NULL;
+
+ convert_efi_path(file_path_str);
+ return xpool_print(u"%s.extra.d", file_path_str);
+}
+
+EFI_STATUS pack_cpio(
+ EFI_LOADED_IMAGE_PROTOCOL *loaded_image,
+ const char16_t *dropin_dir,
+ const char16_t *match_suffix,
+ const char *target_dir_prefix,
+ uint32_t dir_mode,
+ uint32_t access_mode,
+ const uint32_t tpm_pcr[],
+ UINTN n_tpm_pcr,
+ const char16_t *tpm_description,
+ void **ret_buffer,
+ UINTN *ret_buffer_size,
+ bool *ret_measured) {
+
+ _cleanup_(file_closep) EFI_FILE *root = NULL, *extra_dir = NULL;
+ UINTN dirent_size = 0, buffer_size = 0, n_items = 0, n_allocated = 0;
+ _cleanup_free_ char16_t *rel_dropin_dir = NULL;
+ _cleanup_free_ EFI_FILE_INFO *dirent = NULL;
+ _cleanup_(strv_freep) char16_t **items = NULL;
+ _cleanup_free_ void *buffer = NULL;
+ uint32_t inode = 1; /* inode counter, so that each item gets a new inode */
+ EFI_STATUS err;
+
+ assert(loaded_image);
+ assert(target_dir_prefix);
+ assert(tpm_pcr || n_tpm_pcr == 0);
+ assert(ret_buffer);
+ assert(ret_buffer_size);
+
+ if (!loaded_image->DeviceHandle)
+ goto nothing;
+
+ err = open_volume(loaded_image->DeviceHandle, &root);
+ if (err == EFI_UNSUPPORTED)
+ /* Error will be unsupported if the bootloader doesn't implement the file system protocol on
+ * its file handles. */
+ goto nothing;
+ if (err != EFI_SUCCESS)
+ return log_error_status_stall(
+ err, L"Unable to open root directory: %r", err);
+
+ if (!dropin_dir)
+ dropin_dir = rel_dropin_dir = get_dropin_dir(loaded_image->FilePath);
+
+ err = open_directory(root, dropin_dir, &extra_dir);
+ if (err == EFI_NOT_FOUND)
+ /* No extra subdir, that's totally OK */
+ goto nothing;
+ if (err != EFI_SUCCESS)
+ return log_error_status_stall(err, L"Failed to open extra directory of loaded image: %r", err);
+
+ for (;;) {
+ _cleanup_free_ char16_t *d = NULL;
+
+ err = readdir_harder(extra_dir, &dirent, &dirent_size);
+ if (err != EFI_SUCCESS)
+ return log_error_status_stall(err, L"Failed to read extra directory of loaded image: %r", err);
+ if (!dirent) /* End of directory */
+ break;
+
+ if (dirent->FileName[0] == '.')
+ continue;
+ if (FLAGS_SET(dirent->Attribute, EFI_FILE_DIRECTORY))
+ continue;
+ if (match_suffix && !endswith_no_case(dirent->FileName, match_suffix))
+ continue;
+ if (!is_ascii(dirent->FileName))
+ continue;
+ if (strlen16(dirent->FileName) > 255) /* Max filename size on Linux */
+ continue;
+
+ d = xstrdup16(dirent->FileName);
+
+ if (n_items+2 > n_allocated) {
+ UINTN m;
+
+ /* We allocate 16 entries at a time, as a matter of optimization */
+ if (n_items > (UINTN_MAX / sizeof(uint16_t)) - 16) /* Overflow check, just in case */
+ return log_oom();
+
+ m = n_items + 16;
+ items = xrealloc(items, n_allocated * sizeof(uint16_t *), m * sizeof(uint16_t *));
+ n_allocated = m;
+ }
+
+ items[n_items++] = TAKE_PTR(d);
+ items[n_items] = NULL; /* Let's always NUL terminate, to make freeing via strv_free() easy */
+ }
+
+ if (n_items == 0)
+ /* Empty directory */
+ goto nothing;
+
+ /* Now, sort the files we found, to make this uniform and stable (and to ensure the TPM measurements
+ * are not dependent on read order) */
+ sort_pointer_array((void**) items, n_items, (compare_pointer_func_t) strcmp16);
+
+ /* Generate the leading directory inodes right before adding the first files, to the
+ * archive. Otherwise the cpio archive cannot be unpacked, since the leading dirs won't exist. */
+ err = pack_cpio_prefix(target_dir_prefix, dir_mode, &inode, &buffer, &buffer_size);
+ if (err != EFI_SUCCESS)
+ return log_error_status_stall(err, L"Failed to pack cpio prefix: %r", err);
+
+ for (UINTN i = 0; i < n_items; i++) {
+ _cleanup_free_ char *content = NULL;
+ UINTN contentsize = 0; /* avoid false maybe-uninitialized warning */
+
+ err = file_read(extra_dir, items[i], 0, 0, &content, &contentsize);
+ if (err != EFI_SUCCESS) {
+ log_error_status_stall(err, L"Failed to read %s, ignoring: %r", items[i], err);
+ continue;
+ }
+
+ err = pack_cpio_one(
+ items[i],
+ content, contentsize,
+ target_dir_prefix,
+ access_mode,
+ &inode,
+ &buffer, &buffer_size);
+ if (err != EFI_SUCCESS)
+ return log_error_status_stall(err, L"Failed to pack cpio file %s: %r", dirent->FileName, err);
+ }
+
+ err = pack_cpio_trailer(&buffer, &buffer_size);
+ if (err != EFI_SUCCESS)
+ return log_error_status_stall(err, L"Failed to pack cpio trailer: %r");
+
+ err = measure_cpio(buffer, buffer_size, tpm_pcr, n_tpm_pcr, tpm_description, ret_measured);
+ if (err != EFI_SUCCESS)
+ return err;
+
+ *ret_buffer = TAKE_PTR(buffer);
+ *ret_buffer_size = buffer_size;
+
+ return EFI_SUCCESS;
+
+nothing:
+ *ret_buffer = NULL;
+ *ret_buffer_size = 0;
+
+ if (ret_measured)
+ *ret_measured = n_tpm_pcr > 0;
+
+ return EFI_SUCCESS;
+}
+
+EFI_STATUS pack_cpio_literal(
+ const void *data,
+ size_t data_size,
+ const char *target_dir_prefix,
+ const char16_t *target_filename,
+ uint32_t dir_mode,
+ uint32_t access_mode,
+ const uint32_t tpm_pcr[],
+ UINTN n_tpm_pcr,
+ const char16_t *tpm_description,
+ void **ret_buffer,
+ UINTN *ret_buffer_size,
+ bool *ret_measured) {
+
+ uint32_t inode = 1; /* inode counter, so that each item gets a new inode */
+ _cleanup_free_ void *buffer = NULL;
+ UINTN buffer_size = 0;
+ EFI_STATUS err;
+
+ assert(data || data_size == 0);
+ assert(target_dir_prefix);
+ assert(target_filename);
+ assert(tpm_pcr || n_tpm_pcr == 0);
+ assert(ret_buffer);
+ assert(ret_buffer_size);
+
+ /* Generate the leading directory inodes right before adding the first files, to the
+ * archive. Otherwise the cpio archive cannot be unpacked, since the leading dirs won't exist. */
+
+ err = pack_cpio_prefix(target_dir_prefix, dir_mode, &inode, &buffer, &buffer_size);
+ if (err != EFI_SUCCESS)
+ return log_error_status_stall(err, L"Failed to pack cpio prefix: %r", err);
+
+ err = pack_cpio_one(
+ target_filename,
+ data, data_size,
+ target_dir_prefix,
+ access_mode,
+ &inode,
+ &buffer, &buffer_size);
+ if (err != EFI_SUCCESS)
+ return log_error_status_stall(err, L"Failed to pack cpio file %s: %r", target_filename, err);
+
+ err = pack_cpio_trailer(&buffer, &buffer_size);
+ if (err != EFI_SUCCESS)
+ return log_error_status_stall(err, L"Failed to pack cpio trailer: %r");
+
+ err = measure_cpio(buffer, buffer_size, tpm_pcr, n_tpm_pcr, tpm_description, ret_measured);
+ if (err != EFI_SUCCESS)
+ return err;
+
+ *ret_buffer = TAKE_PTR(buffer);
+ *ret_buffer_size = buffer_size;
+
+ return EFI_SUCCESS;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-05 20:07:21 +0000