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b5ee8ec4e8eb80a598a585663986f1334bbc680a
systemd/src/import/pull-common.c
Thorsten Kukuk ac9edf9911 systemd-pull: support .asc and .sha256.* signature
2025-02-06 16:49:36 +01:00

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/* 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 "discover-image.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 "rm-rf.h"
#include "signal-util.h"
#include "siphash24.h"
#include "string-util.h"
#include "strv.h"
#include "tmpfile-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(image_root);
assert(etags);
_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(image_root);
assert(ret);
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 SignatureStyle signature_style_from_filename(const char *fn) {
/* Returns true if the specified filename refers to a signature file we grok */
if (!fn)
return _SIGNATURE_STYLE_INVALID;
if (streq(fn, "SHA256SUMS.gpg"))
return SIGNATURE_GPG_PER_DIRECTORY;
if (streq(fn, "SHA256SUMS.asc"))
return SIGNATURE_ASC_PER_DIRECTORY;
if (endswith(fn, ".sha256.gpg"))
return SIGNATURE_GPG_PER_FILE;
if (endswith(fn, ".sha256.asc"))
return SIGNATURE_ASC_PER_FILE;
return _SIGNATURE_STYLE_INVALID;
}
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) && signature_style_from_filename(fn) < 0) {
_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 && signature_style_from_filename(fn) < 0) {
_cleanup_free_ char *signature_url = NULL;
const char *suffixed = NULL;
if (fn)
suffixed = strjoina(fn, ".sha256.asc"); /* Start with the suse-style checksum (if there's a base filename) */
else
suffixed = "SHA256SUMS.gpg";
/* Queue job for the signature file for the image. */
r = import_url_change_last_component(url, suffixed, &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;
signature_job->on_not_found = pull_job_restart_with_signature;
}
*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) || signature_style_from_filename(fn) >= 0) /* 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] = EBADF_PAIR;
_cleanup_(rm_rf_physical_and_freep) char *gpg_home = NULL;
char sig_file_path[] = "/tmp/sigXXXXXX";
_cleanup_(sigkill_waitp) pid_t pid = 0;
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 = -EBADF;
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);
if (r < 0) {
log_error_errno(r, "Failed to write to temporary file: %m");
goto finish;
}
}
r = mkdtemp_malloc("/tmp/gpghomeXXXXXX", &gpg_home);
if (r < 0) {
log_error_errno(r, "Failed to create temporary home for gpg: %m");
goto finish;
}
r = safe_fork_full("(gpg)",
(int[]) { gpg_pipe[0], -EBADF, STDERR_FILENO },
NULL, 0,
FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_DEATHSIG_SIGTERM|FORK_REARRANGE_STDIO|FORK_LOG|FORK_RLIMIT_NOFILE_SAFE,
&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 */
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);
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);
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 (signature_style_from_filename(fn) >= 0)
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 {
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.");
PullJob *j;
FOREACH_ARGUMENT(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);
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);
}
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 */
*ret = NULL;
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;
}
int signature_style_from_url(const char *url, SignatureStyle *ret, char **ret_filename) {
_cleanup_free_ char *last = NULL;
SignatureStyle style;
int r;
assert(url);
assert(ret);
assert(ret_filename);
/* Determines which kind of signature style is appropriate for this url */
r = import_url_last_component(url, &last);
if (r < 0)
return r;
style = signature_style_from_filename(last);
if (style < 0)
return style;
*ret_filename = TAKE_PTR(last);
*ret = style;
return 0;
}
int pull_job_restart_with_signature(PullJob *j, char **ret) {
_cleanup_free_ char *last = NULL;
SignatureStyle style;
int r;
assert(j);
/* Generic implementation of a PullJobNotFound handler, that restarts the job requesting a different
* signature file. After the initial file, additional *.sha256.gpg, SHA256SUMS.gpg and SHA256SUMS.asc
* are tried in this order. */
r = signature_style_from_url(j->url, &style, &last);
if (r < 0)
return log_error_errno(r, "Failed to determine signature style of URL '%s': %m", j->url);
switch (style) {
case SIGNATURE_ASC_PER_DIRECTORY: /* Nothing to do anymore */
*ret = NULL;
return 0;
case SIGNATURE_ASC_PER_FILE: { /* Try .sha256.gpg next */
char *ext;
log_debug("Got 404 for '%s', now trying to get .sha256.gpg instead.", j->url);
ext = endswith(last, ".asc");
assert(ext);
strcpy(ext, ".gpg");
r = import_url_change_last_component(j->url, last, ret);
if (r < 0)
return log_error_errno(r, "Failed to replace .sha256.asc suffix: %m");
break;
}
case SIGNATURE_GPG_PER_FILE: /* Try SHA256SUMS.gpg next */
log_debug("Got 404 for '%s', now trying to get SHA256SUMS.gpg instead.", j->url);
r = import_url_change_last_component(j->url, "SHA256SUMS.gpg", ret);
if (r < 0)
return log_error_errno(r, "Failed to replace SHA256SUMS suffix: %m");
break;
case SIGNATURE_GPG_PER_DIRECTORY:
log_debug("Got 404 for '%s', now trying to get SHA256SUMS.asc instead.", j->url);
r = import_url_change_last_component(j->url, "SHA256SUMS.asc", ret);
if (r < 0)
return log_error_errno(r, "Failed to replace SHA256SUMS.gpg suffix: %m");
break;
default:
assert_not_reached();
}
return 1;
}
bool pull_validate_local(const char *name, ImportFlags flags) {
if (FLAGS_SET(flags, IMPORT_DIRECT))
return path_is_valid(name);
return image_name_is_valid(name);
}
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) && signature_style_from_filename(fn) < 0;
}
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