Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 239 insertions, 0 deletions

diff --git a/src/boot/bootctl-random-seed.c b/src/boot/bootctl-random-seed.c
new file mode 100644
index 0000000..cfe10c4
--- /dev/null
+++ b/src/boot/bootctl-random-seed.c
@@ -0,0 +1,239 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "alloc-util.h"
+#include "bootctl.h"
+#include "bootctl-random-seed.h"
+#include "bootctl-util.h"
+#include "efi-api.h"
+#include "env-util.h"
+#include "fd-util.h"
+#include "find-esp.h"
+#include "fs-util.h"
+#include "glyph-util.h"
+#include "io-util.h"
+#include "mkdir.h"
+#include "path-util.h"
+#include "random-util.h"
+#include "sha256.h"
+#include "tmpfile-util.h"
+#include "umask-util.h"
+
+static int random_seed_verify_permissions(int fd, mode_t expected_type) {
+        _cleanup_free_ char *full_path = NULL;
+        struct stat st;
+        int r;
+
+        assert(fd >= 0);
+
+        r = fd_get_path(fd, &full_path);
+        if (r < 0)
+                return log_error_errno(r, "Unable to determine full path of random seed fd: %m");
+
+        if (fstat(fd, &st) < 0)
+                return log_error_errno(errno, "Unable to stat %s: %m", full_path);
+
+        if (((st.st_mode ^ expected_type) & S_IFMT) != 0)
+                return log_error_errno(SYNTHETIC_ERRNO(EBADF),
+                                       "Unexpected inode type when validating random seed access mode on %s: %m", full_path);
+
+        if ((st.st_mode & 0007) == 0) /* All world bits are off? Then all is good */
+                return 0;
+
+        if (S_ISREG(expected_type))
+                log_warning("%s Random seed file '%s' is world accessible, which is a security hole! %s",
+                            special_glyph(SPECIAL_GLYPH_WARNING_SIGN), full_path, special_glyph(SPECIAL_GLYPH_WARNING_SIGN));
+        else {
+                assert(S_ISDIR(expected_type));
+                log_warning("%s Mount point '%s' which backs the random seed file is world accessible, which is a security hole! %s",
+                            special_glyph(SPECIAL_GLYPH_WARNING_SIGN), full_path, special_glyph(SPECIAL_GLYPH_WARNING_SIGN));
+        }
+
+        return 1;
+}
+
+static int set_system_token(void) {
+        uint8_t buffer[RANDOM_EFI_SEED_SIZE];
+        size_t token_size;
+        int r;
+
+        if (!arg_touch_variables)
+                return 0;
+
+        if (arg_root) {
+                log_warning("Acting on %s, skipping EFI variable setup.",
+                             arg_image ? "image" : "root directory");
+                return 0;
+        }
+
+        if (!is_efi_boot()) {
+                log_notice("Not booted with EFI, skipping EFI variable setup.");
+                return 0;
+        }
+
+        r = getenv_bool("SYSTEMD_WRITE_SYSTEM_TOKEN");
+        if (r < 0) {
+                if (r != -ENXIO)
+                        log_warning_errno(r, "Failed to parse $SYSTEMD_WRITE_SYSTEM_TOKEN, ignoring.");
+        } else if (r == 0) {
+                log_notice("Not writing system token, because $SYSTEMD_WRITE_SYSTEM_TOKEN is set to false.");
+                return 0;
+        }
+
+        r = efi_get_variable(EFI_LOADER_VARIABLE(LoaderSystemToken), NULL, NULL, &token_size);
+        if (r == -ENODATA)
+                log_debug_errno(r, "LoaderSystemToken EFI variable is invalid (too short?), replacing.");
+        else if (r < 0) {
+                if (r != -ENOENT)
+                        return log_error_errno(r, "Failed to test system token validity: %m");
+        } else {
+                if (token_size >= sizeof(buffer)) {
+                        /* Let's avoid writes if we can, and initialize this only once. */
+                        log_debug("System token already written, not updating.");
+                        return 0;
+                }
+
+                log_debug("Existing system token size (%zu) does not match our expectations (%zu), replacing.", token_size, sizeof(buffer));
+        }
+
+        r = crypto_random_bytes(buffer, sizeof(buffer));
+        if (r < 0)
+                return log_error_errno(r, "Failed to acquire random seed: %m");
+
+        /* Let's write this variable with an umask in effect, so that unprivileged users can't see the token
+         * and possibly get identification information or too much insight into the kernel's entropy pool
+         * state. */
+        WITH_UMASK(0077) {
+                r = efi_set_variable(EFI_LOADER_VARIABLE(LoaderSystemToken), buffer, sizeof(buffer));
+                if (r < 0) {
+                        if (!arg_graceful)
+                                return log_error_errno(r, "Failed to write 'LoaderSystemToken' EFI variable: %m");
+
+                        if (r == -EINVAL)
+                                log_notice_errno(r, "Unable to write 'LoaderSystemToken' EFI variable (firmware problem?), ignoring: %m");
+                        else
+                                log_notice_errno(r, "Unable to write 'LoaderSystemToken' EFI variable, ignoring: %m");
+                } else
+                        log_info("Successfully initialized system token in EFI variable with %zu bytes.", sizeof(buffer));
+        }
+
+        return 0;
+}
+
+int install_random_seed(const char *esp) {
+        _cleanup_close_ int esp_fd = -EBADF, loader_dir_fd = -EBADF, fd = -EBADF;
+        _cleanup_free_ char *tmp = NULL;
+        uint8_t buffer[RANDOM_EFI_SEED_SIZE];
+        struct sha256_ctx hash_state;
+        bool refreshed, warned = false;
+        int r;
+
+        assert(esp);
+
+        assert_cc(RANDOM_EFI_SEED_SIZE == SHA256_DIGEST_SIZE);
+
+        esp_fd = open(esp, O_DIRECTORY|O_RDONLY|O_CLOEXEC);
+        if (esp_fd < 0)
+                return log_error_errno(errno, "Failed to open ESP directory '%s': %m", esp);
+
+        (void) random_seed_verify_permissions(esp_fd, S_IFDIR);
+
+        loader_dir_fd = open_mkdir_at(esp_fd, "loader", O_DIRECTORY|O_RDONLY|O_CLOEXEC|O_NOFOLLOW, 0775);
+        if (loader_dir_fd < 0)
+                return log_error_errno(loader_dir_fd, "Failed to open loader directory '%s/loader': %m", esp);
+
+        r = crypto_random_bytes(buffer, sizeof(buffer));
+        if (r < 0)
+                return log_error_errno(r, "Failed to acquire random seed: %m");
+
+        sha256_init_ctx(&hash_state);
+        sha256_process_bytes_and_size(buffer, sizeof(buffer), &hash_state);
+
+        fd = openat(loader_dir_fd, "random-seed", O_NOFOLLOW|O_CLOEXEC|O_RDONLY|O_NOCTTY);
+        if (fd < 0) {
+                if (errno != ENOENT)
+                        return log_error_errno(errno, "Failed to open old random seed file: %m");
+
+                sha256_process_bytes(&(const ssize_t) { 0 }, sizeof(ssize_t), &hash_state);
+                refreshed = false;
+        } else {
+                ssize_t n;
+
+                warned = random_seed_verify_permissions(fd, S_IFREG) > 0;
+
+                /* Hash the old seed in so that we never regress in entropy. */
+
+                n = read(fd, buffer, sizeof(buffer));
+                if (n < 0)
+                        return log_error_errno(errno, "Failed to read old random seed file: %m");
+
+                sha256_process_bytes_and_size(buffer, n, &hash_state);
+
+                fd = safe_close(fd);
+                refreshed = n > 0;
+        }
+
+        sha256_finish_ctx(&hash_state, buffer);
+
+        if (tempfn_random("random-seed", "bootctl", &tmp) < 0)
+                return log_oom();
+
+        fd = openat(loader_dir_fd, tmp, O_CREAT|O_EXCL|O_NOFOLLOW|O_NOCTTY|O_WRONLY|O_CLOEXEC, 0600);
+        if (fd < 0)
+                return log_error_errno(fd, "Failed to open random seed file for writing: %m");
+
+        if (!warned) /* only warn once per seed file */
+                (void) random_seed_verify_permissions(fd, S_IFREG);
+
+        r = loop_write(fd, buffer, sizeof(buffer));
+        if (r < 0) {
+                log_error_errno(r, "Failed to write random seed file: %m");
+                goto fail;
+        }
+
+        if (fsync(fd) < 0 || fsync(loader_dir_fd) < 0) {
+                r = log_error_errno(errno, "Failed to sync random seed file: %m");
+                goto fail;
+        }
+
+        if (renameat(loader_dir_fd, tmp, loader_dir_fd, "random-seed") < 0) {
+                r = log_error_errno(errno, "Failed to move random seed file into place: %m");
+                goto fail;
+        }
+
+        tmp = mfree(tmp);
+
+        if (syncfs(fd) < 0)
+                return log_error_errno(errno, "Failed to sync ESP file system: %m");
+
+        log_info("Random seed file %s/loader/random-seed successfully %s (%zu bytes).", esp, refreshed ? "refreshed" : "written", sizeof(buffer));
+
+        return set_system_token();
+
+fail:
+        assert(tmp);
+        (void) unlinkat(loader_dir_fd, tmp, 0);
+
+        return r;
+}
+
+int verb_random_seed(int argc, char *argv[], void *userdata) {
+        int r;
+
+        r = find_esp_and_warn(arg_root, arg_esp_path, false, &arg_esp_path, NULL, NULL, NULL, NULL, NULL);
+        if (r == -ENOKEY) {
+                /* find_esp_and_warn() doesn't warn about ENOKEY, so let's do that on our own */
+                if (!arg_graceful)
+                        return log_error_errno(r, "Unable to find ESP.");
+
+                log_notice("No ESP found, not initializing random seed.");
+                return 0;
+        }
+        if (r < 0)
+                return r;
+
+        r = install_random_seed(arg_esp_path);
+        if (r < 0)
+                return r;
+
+        return 0;
+}