diff options
Diffstat (limited to 'src/import/pull-common.c')
-rw-r--r-- | src/import/pull-common.c | 677 |
1 files changed, 677 insertions, 0 deletions
diff --git a/src/import/pull-common.c b/src/import/pull-common.c new file mode 100644 index 0000000..028bae8 --- /dev/null +++ b/src/import/pull-common.c @@ -0,0 +1,677 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <sys/prctl.h> + +#include "alloc-util.h" +#include "btrfs-util.h" +#include "capability-util.h" +#include "copy.h" +#include "dirent-util.h" +#include "escape.h" +#include "fd-util.h" +#include "hostname-util.h" +#include "io-util.h" +#include "memory-util.h" +#include "path-util.h" +#include "process-util.h" +#include "pull-common.h" +#include "pull-job.h" +#include "rlimit-util.h" +#include "rm-rf.h" +#include "signal-util.h" +#include "siphash24.h" +#include "string-util.h" +#include "strv.h" +#include "util.h" +#include "web-util.h" + +#define FILENAME_ESCAPE "/.#\"\'" +#define HASH_URL_THRESHOLD_LENGTH (_POSIX_PATH_MAX - 16) + +int pull_find_old_etags( + const char *url, + const char *image_root, + int dt, + const char *prefix, + const char *suffix, + char ***etags) { + + int r; + + assert(url); + assert(etags); + + if (!image_root) + image_root = "/var/lib/machines"; + + _cleanup_free_ char *escaped_url = xescape(url, FILENAME_ESCAPE); + if (!escaped_url) + return -ENOMEM; + + _cleanup_closedir_ DIR *d = opendir(image_root); + if (!d) { + if (errno == ENOENT) { + *etags = NULL; + return 0; + } + + return -errno; + } + + _cleanup_strv_free_ char **ans = NULL; + + FOREACH_DIRENT_ALL(de, d, return -errno) { + _cleanup_free_ char *u = NULL; + const char *a, *b; + + if (de->d_type != DT_UNKNOWN && + de->d_type != dt) + continue; + + if (prefix) { + a = startswith(de->d_name, prefix); + if (!a) + continue; + } else + a = de->d_name; + + a = startswith(a, escaped_url); + if (!a) + continue; + + a = startswith(a, "."); + if (!a) + continue; + + if (suffix) { + b = endswith(de->d_name, suffix); + if (!b) + continue; + } else + b = strchr(de->d_name, 0); + + if (a >= b) + continue; + + ssize_t l = cunescape_length(a, b - a, 0, &u); + if (l < 0) { + assert(l >= INT8_MIN); + return l; + } + + if (!http_etag_is_valid(u)) + continue; + + r = strv_consume(&ans, TAKE_PTR(u)); + if (r < 0) + return r; + } + + *etags = TAKE_PTR(ans); + + return 0; +} + +static int hash_url(const char *url, char **ret) { + uint64_t h; + static const sd_id128_t k = SD_ID128_ARRAY(df,89,16,87,01,cc,42,30,98,ab,4a,19,a6,a5,63,4f); + + assert(url); + + h = siphash24(url, strlen(url), k.bytes); + if (asprintf(ret, "%"PRIx64, h) < 0) + return -ENOMEM; + + return 0; +} + +int pull_make_path(const char *url, const char *etag, const char *image_root, const char *prefix, const char *suffix, char **ret) { + _cleanup_free_ char *escaped_url = NULL, *escaped_etag = NULL; + char *path; + + assert(url); + assert(ret); + + if (!image_root) + image_root = "/var/lib/machines"; + + escaped_url = xescape(url, FILENAME_ESCAPE); + if (!escaped_url) + return -ENOMEM; + + if (etag) { + escaped_etag = xescape(etag, FILENAME_ESCAPE); + if (!escaped_etag) + return -ENOMEM; + } + + path = strjoin(image_root, "/", strempty(prefix), escaped_url, escaped_etag ? "." : "", + strempty(escaped_etag), strempty(suffix)); + if (!path) + return -ENOMEM; + + /* URLs might make the path longer than the maximum allowed length for a file name. + * When that happens, a URL hash is used instead. Paths returned by this function + * can be later used with tempfn_random() which adds 16 bytes to the resulting name. */ + if (strlen(path) >= HASH_URL_THRESHOLD_LENGTH) { + _cleanup_free_ char *hash = NULL; + int r; + + free(path); + + r = hash_url(url, &hash); + if (r < 0) + return r; + + path = strjoin(image_root, "/", strempty(prefix), hash, escaped_etag ? "." : "", + strempty(escaped_etag), strempty(suffix)); + if (!path) + return -ENOMEM; + } + + *ret = path; + return 0; +} + +int pull_make_auxiliary_job( + PullJob **ret, + const char *url, + int (*strip_suffixes)(const char *name, char **ret), + const char *suffix, + ImportVerify verify, + CurlGlue *glue, + PullJobOpenDisk on_open_disk, + PullJobFinished on_finished, + void *userdata) { + + _cleanup_free_ char *last_component = NULL, *ll = NULL, *auxiliary_url = NULL; + _cleanup_(pull_job_unrefp) PullJob *job = NULL; + const char *q; + int r; + + assert(ret); + assert(url); + assert(strip_suffixes); + assert(glue); + + r = import_url_last_component(url, &last_component); + if (r < 0) + return r; + + r = strip_suffixes(last_component, &ll); + if (r < 0) + return r; + + q = strjoina(ll, suffix); + + r = import_url_change_last_component(url, q, &auxiliary_url); + if (r < 0) + return r; + + r = pull_job_new(&job, auxiliary_url, glue, userdata); + if (r < 0) + return r; + + job->on_open_disk = on_open_disk; + job->on_finished = on_finished; + job->compressed_max = job->uncompressed_max = 1ULL * 1024ULL * 1024ULL; + job->calc_checksum = IN_SET(verify, IMPORT_VERIFY_CHECKSUM, IMPORT_VERIFY_SIGNATURE); + + *ret = TAKE_PTR(job); + return 0; +} + +static bool is_checksum_file(const char *fn) { + /* Returns true if the specified filename refers to a checksum file we grok */ + + if (!fn) + return false; + + return streq(fn, "SHA256SUMS") || endswith(fn, ".sha256"); +} + +static bool is_signature_file(const char *fn) { + /* Returns true if the specified filename refers to a signature file we grok (reminder: + * suse-style .sha256 files are inline signed) */ + + if (!fn) + return false; + + return streq(fn, "SHA256SUMS.gpg") || endswith(fn, ".sha256"); +} + +int pull_make_verification_jobs( + PullJob **ret_checksum_job, + PullJob **ret_signature_job, + ImportVerify verify, + const char *checksum, /* set if literal checksum verification is requested, in which case 'verify' is set to _IMPORT_VERIFY_INVALID */ + const char *url, + CurlGlue *glue, + PullJobFinished on_finished, + void *userdata) { + + _cleanup_(pull_job_unrefp) PullJob *checksum_job = NULL, *signature_job = NULL; + _cleanup_free_ char *fn = NULL; + int r; + + assert(ret_checksum_job); + assert(ret_signature_job); + assert(verify == _IMPORT_VERIFY_INVALID || verify < _IMPORT_VERIFY_MAX); + assert(verify == _IMPORT_VERIFY_INVALID || verify >= 0); + assert((verify < 0) || !checksum); + assert(url); + assert(glue); + + /* If verification is turned off, or if the checksum to validate is already specified we don't need + * to download a checksum file or signature, hence shortcut things */ + if (verify == IMPORT_VERIFY_NO || checksum) { + *ret_checksum_job = *ret_signature_job = NULL; + return 0; + } + + r = import_url_last_component(url, &fn); + if (r < 0 && r != -EADDRNOTAVAIL) /* EADDRNOTAVAIL means there was no last component, which is OK for + * us, we'll just assume it's not a checksum/signature file */ + return r; + + /* Acquire the checksum file if verification or signature verification is requested and the main file + * to acquire isn't a checksum or signature file anyway */ + if (verify != IMPORT_VERIFY_NO && !is_checksum_file(fn) && !is_signature_file(fn)) { + _cleanup_free_ char *checksum_url = NULL; + const char *suffixed = NULL; + + /* Queue jobs for the checksum file for the image. */ + + if (fn) + suffixed = strjoina(fn, ".sha256"); /* Start with the suse-style checksum (if there's a base filename) */ + else + suffixed = "SHA256SUMS"; + + r = import_url_change_last_component(url, suffixed, &checksum_url); + if (r < 0) + return r; + + r = pull_job_new(&checksum_job, checksum_url, glue, userdata); + if (r < 0) + return r; + + checksum_job->on_finished = on_finished; + checksum_job->uncompressed_max = checksum_job->compressed_max = 1ULL * 1024ULL * 1024ULL; + checksum_job->on_not_found = pull_job_restart_with_sha256sum; /* if this fails, look for ubuntu-style checksum */ + } + + if (verify == IMPORT_VERIFY_SIGNATURE && !is_signature_file(fn)) { + _cleanup_free_ char *signature_url = NULL; + + /* Queue job for the SHA256SUMS.gpg file for the image. */ + r = import_url_change_last_component(url, "SHA256SUMS.gpg", &signature_url); + if (r < 0) + return r; + + r = pull_job_new(&signature_job, signature_url, glue, userdata); + if (r < 0) + return r; + + signature_job->on_finished = on_finished; + signature_job->uncompressed_max = signature_job->compressed_max = 1ULL * 1024ULL * 1024ULL; + } + + *ret_checksum_job = TAKE_PTR(checksum_job); + *ret_signature_job = TAKE_PTR(signature_job); + return 0; +} + +static int verify_one(PullJob *checksum_job, PullJob *job) { + _cleanup_free_ char *fn = NULL; + const char *line, *p; + int r; + + assert(checksum_job); + + if (!job) + return 0; + + assert(IN_SET(job->state, PULL_JOB_DONE, PULL_JOB_FAILED)); + + /* Don't verify the checksum if we didn't actually successfully download something new */ + if (job->state != PULL_JOB_DONE) + return 0; + if (job->error != 0) + return 0; + if (job->etag_exists) + return 0; + + assert(job->calc_checksum); + assert(job->checksum); + + r = import_url_last_component(job->url, &fn); + if (r < 0) + return log_error_errno(r, "Failed to extract filename from URL '%s': %m", job->url); + + if (!filename_is_valid(fn)) + return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), + "Cannot verify checksum, could not determine server-side file name."); + + if (is_checksum_file(fn) || is_signature_file(fn)) /* We cannot verify checksum files or signature files with a checksum file */ + return log_error_errno(SYNTHETIC_ERRNO(ELOOP), + "Cannot verify checksum/signature files via themselves."); + + line = strjoina(job->checksum, " *", fn, "\n"); /* string for binary mode */ + p = memmem_safe(checksum_job->payload, + checksum_job->payload_size, + line, + strlen(line)); + if (!p) { + line = strjoina(job->checksum, " ", fn, "\n"); /* string for text mode */ + p = memmem_safe(checksum_job->payload, + checksum_job->payload_size, + line, + strlen(line)); + } + + /* Only counts if found at beginning of a line */ + if (!p || (p != (char*) checksum_job->payload && p[-1] != '\n')) + return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), + "DOWNLOAD INVALID: Checksum of %s file did not check out, file has been tampered with.", fn); + + log_info("SHA256 checksum of %s is valid.", job->url); + return 1; +} + +static int verify_gpg( + const void *payload, size_t payload_size, + const void *signature, size_t signature_size) { + + _cleanup_close_pair_ int gpg_pipe[2] = { -1, -1 }; + char sig_file_path[] = "/tmp/sigXXXXXX", gpg_home[] = "/tmp/gpghomeXXXXXX"; + _cleanup_(sigkill_waitp) pid_t pid = 0; + bool gpg_home_created = false; + int r; + + assert(payload || payload_size == 0); + assert(signature || signature_size == 0); + + r = pipe2(gpg_pipe, O_CLOEXEC); + if (r < 0) + return log_error_errno(errno, "Failed to create pipe for gpg: %m"); + + if (signature_size > 0) { + _cleanup_close_ int sig_file = -1; + + sig_file = mkostemp(sig_file_path, O_RDWR); + if (sig_file < 0) + return log_error_errno(errno, "Failed to create temporary file: %m"); + + r = loop_write(sig_file, signature, signature_size, false); + if (r < 0) { + log_error_errno(r, "Failed to write to temporary file: %m"); + goto finish; + } + } + + if (!mkdtemp(gpg_home)) { + r = log_error_errno(errno, "Failed to create temporary home for gpg: %m"); + goto finish; + } + + gpg_home_created = true; + + r = safe_fork("(gpg)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_LOG, &pid); + if (r < 0) + return r; + if (r == 0) { + const char *cmd[] = { + "gpg", + "--no-options", + "--no-default-keyring", + "--no-auto-key-locate", + "--no-auto-check-trustdb", + "--batch", + "--trust-model=always", + NULL, /* --homedir= */ + NULL, /* --keyring= */ + NULL, /* --verify */ + NULL, /* signature file */ + NULL, /* dash */ + NULL /* trailing NULL */ + }; + size_t k = ELEMENTSOF(cmd) - 6; + + /* Child */ + + gpg_pipe[1] = safe_close(gpg_pipe[1]); + + r = rearrange_stdio(TAKE_FD(gpg_pipe[0]), -1, STDERR_FILENO); + if (r < 0) { + log_error_errno(r, "Failed to rearrange stdin/stdout: %m"); + _exit(EXIT_FAILURE); + } + + (void) rlimit_nofile_safe(); + + cmd[k++] = strjoina("--homedir=", gpg_home); + + /* We add the user keyring only to the command line arguments, if it's around since gpg fails + * otherwise. */ + if (access(USER_KEYRING_PATH, F_OK) >= 0) + cmd[k++] = "--keyring=" USER_KEYRING_PATH; + else + cmd[k++] = "--keyring=" VENDOR_KEYRING_PATH; + + cmd[k++] = "--verify"; + if (signature) { + cmd[k++] = sig_file_path; + cmd[k++] = "-"; + cmd[k++] = NULL; + } + + execvp("gpg2", (char * const *) cmd); + execvp("gpg", (char * const *) cmd); + log_error_errno(errno, "Failed to execute gpg: %m"); + _exit(EXIT_FAILURE); + } + + gpg_pipe[0] = safe_close(gpg_pipe[0]); + + r = loop_write(gpg_pipe[1], payload, payload_size, false); + if (r < 0) { + log_error_errno(r, "Failed to write to pipe: %m"); + goto finish; + } + + gpg_pipe[1] = safe_close(gpg_pipe[1]); + + r = wait_for_terminate_and_check("gpg", TAKE_PID(pid), WAIT_LOG_ABNORMAL); + if (r < 0) + goto finish; + if (r != EXIT_SUCCESS) + r = log_error_errno(SYNTHETIC_ERRNO(EBADMSG), + "DOWNLOAD INVALID: Signature verification failed."); + else { + log_info("Signature verification succeeded."); + r = 0; + } + +finish: + if (signature_size > 0) + (void) unlink(sig_file_path); + + if (gpg_home_created) + (void) rm_rf(gpg_home, REMOVE_ROOT|REMOVE_PHYSICAL); + + return r; +} + +int pull_verify(ImportVerify verify, + const char *checksum, /* Verify with literal checksum */ + PullJob *main_job, + PullJob *checksum_job, + PullJob *signature_job, + PullJob *settings_job, + PullJob *roothash_job, + PullJob *roothash_signature_job, + PullJob *verity_job) { + + _cleanup_free_ char *fn = NULL; + VerificationStyle style; + PullJob *verify_job; + int r; + + assert(verify == _IMPORT_VERIFY_INVALID || verify < _IMPORT_VERIFY_MAX); + assert(verify == _IMPORT_VERIFY_INVALID || verify >= 0); + assert((verify < 0) || !checksum); + assert(main_job); + assert(main_job->state == PULL_JOB_DONE); + + if (verify == IMPORT_VERIFY_NO) /* verification turned off */ + return 0; + + if (checksum) { + /* Verification by literal checksum */ + assert(!checksum_job); + assert(!signature_job); + assert(!settings_job); + assert(!roothash_job); + assert(!roothash_signature_job); + assert(!verity_job); + + assert(main_job->calc_checksum); + assert(main_job->checksum); + + if (!strcaseeq(checksum, main_job->checksum)) + return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), + "DOWNLOAD INVALID: Checksum of %s file did not check out, file has been tampered with.", + main_job->url); + + return 0; + } + + r = import_url_last_component(main_job->url, &fn); + if (r < 0) + return log_error_errno(r, "Failed to extract filename from URL '%s': %m", main_job->url); + + if (is_signature_file(fn)) + return log_error_errno(SYNTHETIC_ERRNO(ELOOP), + "Main download is a signature file, can't verify it."); + + if (is_checksum_file(fn)) { + log_debug("Main download is a checksum file, can't validate its checksum with itself, skipping."); + verify_job = main_job; + } else { + PullJob *j; + assert(main_job->calc_checksum); + assert(main_job->checksum); + assert(checksum_job); + assert(checksum_job->state == PULL_JOB_DONE); + + if (!checksum_job->payload || checksum_job->payload_size <= 0) + return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), + "Checksum is empty, cannot verify."); + + FOREACH_POINTER(j, main_job, settings_job, roothash_job, roothash_signature_job, verity_job) { + r = verify_one(checksum_job, j); + if (r < 0) + return r; + } + + verify_job = checksum_job; + } + + if (verify != IMPORT_VERIFY_SIGNATURE) + return 0; + + assert(verify_job); + + r = verification_style_from_url(verify_job->url, &style); + if (r < 0) + return log_error_errno(r, "Failed to determine verification style from URL '%s': %m", verify_job->url); + + if (style == VERIFICATION_PER_DIRECTORY) { + assert(signature_job); + assert(signature_job->state == PULL_JOB_DONE); + + if (!signature_job->payload || signature_job->payload_size <= 0) + return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), + "Signature is empty, cannot verify."); + + return verify_gpg(verify_job->payload, verify_job->payload_size, signature_job->payload, signature_job->payload_size); + } else + return verify_gpg(verify_job->payload, verify_job->payload_size, NULL, 0); +} + +int verification_style_from_url(const char *url, VerificationStyle *ret) { + _cleanup_free_ char *last = NULL; + int r; + + assert(url); + assert(ret); + + /* Determines which kind of verification style is appropriate for this url */ + + r = import_url_last_component(url, &last); + if (r < 0) + return r; + + if (streq(last, "SHA256SUMS")) { + *ret = VERIFICATION_PER_DIRECTORY; + return 0; + } + + if (endswith(last, ".sha256")) { + *ret = VERIFICATION_PER_FILE; + return 0; + } + + return -EINVAL; +} + +int pull_job_restart_with_sha256sum(PullJob *j, char **ret) { + VerificationStyle style; + int r; + + assert(j); + + /* Generic implementation of a PullJobNotFound handler, that restarts the job requesting SHA256SUMS */ + + r = verification_style_from_url(j->url, &style); + if (r < 0) + return log_error_errno(r, "Failed to determine verification style of URL '%s': %m", j->url); + + if (style == VERIFICATION_PER_DIRECTORY) /* Nothing to do anymore */ + return 0; + + assert(style == VERIFICATION_PER_FILE); /* This must have been .sha256 style URL before */ + + log_debug("Got 404 for %s, now trying to get SHA256SUMS instead.", j->url); + + r = import_url_change_last_component(j->url, "SHA256SUMS", ret); + if (r < 0) + return log_error_errno(r, "Failed to replace SHA256SUMS suffix: %m"); + + return 1; +} + +bool pull_validate_local(const char *name, PullFlags flags) { + + if (FLAGS_SET(flags, PULL_DIRECT)) + return path_is_valid(name); + + return hostname_is_valid(name, 0); +} + +int pull_url_needs_checksum(const char *url) { + _cleanup_free_ char *fn = NULL; + int r; + + /* Returns true if we need to validate this resource via a hash value. This returns true for all + * files — except for gpg signature files and SHA256SUMS files and the like, which are validated with + * a validation tool like gpg. */ + + r = import_url_last_component(url, &fn); + if (r == -EADDRNOTAVAIL) /* no last component? then let's assume it's not a signature/checksum file */ + return false; + if (r < 0) + return r; + + return !is_checksum_file(fn) && !is_signature_file(fn); +} |