diff options
Diffstat (limited to 'gpg-interface.c')
| -rw-r--r-- | gpg-interface.c | 587 |
1 files changed, 538 insertions, 49 deletions
diff --git a/gpg-interface.c b/gpg-interface.c index 127aecfc2b..3e7255a2a9 100644 --- a/gpg-interface.c +++ b/gpg-interface.c @@ -3,11 +3,14 @@ #include "config.h" #include "run-command.h" #include "strbuf.h" +#include "dir.h" #include "gpg-interface.h" #include "sigchain.h" #include "tempfile.h" +#include "alias.h" static char *configured_signing_key; +static const char *ssh_default_key_command, *ssh_allowed_signers, *ssh_revocation_file; static enum signature_trust_level configured_min_trust_level = TRUST_UNDEFINED; struct gpg_format { @@ -15,6 +18,14 @@ struct gpg_format { const char *program; const char **verify_args; const char **sigs; + int (*verify_signed_buffer)(struct signature_check *sigc, + struct gpg_format *fmt, const char *payload, + size_t payload_size, const char *signature, + size_t signature_size); + int (*sign_buffer)(struct strbuf *buffer, struct strbuf *signature, + const char *signing_key); + const char *(*get_default_key)(void); + const char *(*get_key_id)(void); }; static const char *openpgp_verify_args[] = { @@ -35,14 +46,59 @@ static const char *x509_sigs[] = { NULL }; +static const char *ssh_verify_args[] = { NULL }; +static const char *ssh_sigs[] = { + "-----BEGIN SSH SIGNATURE-----", + NULL +}; + +static int verify_gpg_signed_buffer(struct signature_check *sigc, + struct gpg_format *fmt, const char *payload, + size_t payload_size, const char *signature, + size_t signature_size); +static int verify_ssh_signed_buffer(struct signature_check *sigc, + struct gpg_format *fmt, const char *payload, + size_t payload_size, const char *signature, + size_t signature_size); +static int sign_buffer_gpg(struct strbuf *buffer, struct strbuf *signature, + const char *signing_key); +static int sign_buffer_ssh(struct strbuf *buffer, struct strbuf *signature, + const char *signing_key); + +static const char *get_default_ssh_signing_key(void); + +static const char *get_ssh_key_id(void); + static struct gpg_format gpg_format[] = { - { .name = "openpgp", .program = "gpg", - .verify_args = openpgp_verify_args, - .sigs = openpgp_sigs + { + .name = "openpgp", + .program = "gpg", + .verify_args = openpgp_verify_args, + .sigs = openpgp_sigs, + .verify_signed_buffer = verify_gpg_signed_buffer, + .sign_buffer = sign_buffer_gpg, + .get_default_key = NULL, + .get_key_id = NULL, + }, + { + .name = "x509", + .program = "gpgsm", + .verify_args = x509_verify_args, + .sigs = x509_sigs, + .verify_signed_buffer = verify_gpg_signed_buffer, + .sign_buffer = sign_buffer_gpg, + .get_default_key = NULL, + .get_key_id = NULL, }, - { .name = "x509", .program = "gpgsm", - .verify_args = x509_verify_args, - .sigs = x509_sigs + { + .name = "ssh", + .program = "ssh-keygen", + .verify_args = ssh_verify_args, + .sigs = ssh_sigs, + .verify_signed_buffer = verify_ssh_signed_buffer, + .sign_buffer = sign_buffer_ssh, + .get_default_key = get_default_ssh_signing_key, + .get_key_id = get_ssh_key_id, }, }; @@ -72,7 +128,7 @@ static struct gpg_format *get_format_by_sig(const char *sig) void signature_check_clear(struct signature_check *sigc) { FREE_AND_NULL(sigc->payload); - FREE_AND_NULL(sigc->gpg_output); + FREE_AND_NULL(sigc->output); FREE_AND_NULL(sigc->gpg_status); FREE_AND_NULL(sigc->signer); FREE_AND_NULL(sigc->key); @@ -257,16 +313,16 @@ error: FREE_AND_NULL(sigc->key); } -static int verify_signed_buffer(const char *payload, size_t payload_size, - const char *signature, size_t signature_size, - struct strbuf *gpg_output, - struct strbuf *gpg_status) +static int verify_gpg_signed_buffer(struct signature_check *sigc, + struct gpg_format *fmt, const char *payload, + size_t payload_size, const char *signature, + size_t signature_size) { struct child_process gpg = CHILD_PROCESS_INIT; - struct gpg_format *fmt; struct tempfile *temp; int ret; - struct strbuf buf = STRBUF_INIT; + struct strbuf gpg_stdout = STRBUF_INIT; + struct strbuf gpg_stderr = STRBUF_INIT; temp = mks_tempfile_t(".git_vtag_tmpXXXXXX"); if (!temp) @@ -279,10 +335,6 @@ static int verify_signed_buffer(const char *payload, size_t payload_size, return -1; } - fmt = get_format_by_sig(signature); - if (!fmt) - BUG("bad signature '%s'", signature); - strvec_push(&gpg.args, fmt->program); strvec_pushv(&gpg.args, fmt->verify_args); strvec_pushl(&gpg.args, @@ -290,18 +342,222 @@ static int verify_signed_buffer(const char *payload, size_t payload_size, "--verify", temp->filename.buf, "-", NULL); - if (!gpg_status) - gpg_status = &buf; - sigchain_push(SIGPIPE, SIG_IGN); - ret = pipe_command(&gpg, payload, payload_size, - gpg_status, 0, gpg_output, 0); + ret = pipe_command(&gpg, payload, payload_size, &gpg_stdout, 0, + &gpg_stderr, 0); sigchain_pop(SIGPIPE); delete_tempfile(&temp); - ret |= !strstr(gpg_status->buf, "\n[GNUPG:] GOODSIG "); - strbuf_release(&buf); /* no matter it was used or not */ + ret |= !strstr(gpg_stdout.buf, "\n[GNUPG:] GOODSIG "); + sigc->payload = xmemdupz(payload, payload_size); + sigc->output = strbuf_detach(&gpg_stderr, NULL); + sigc->gpg_status = strbuf_detach(&gpg_stdout, NULL); + + parse_gpg_output(sigc); + + strbuf_release(&gpg_stdout); + strbuf_release(&gpg_stderr); + + return ret; +} + +static void parse_ssh_output(struct signature_check *sigc) +{ + const char *line, *principal, *search; + char *to_free; + char *key = NULL; + + /* + * ssh-keygen output should be: + * Good "git" signature for PRINCIPAL with RSA key SHA256:FINGERPRINT + * + * or for valid but unknown keys: + * Good "git" signature with RSA key SHA256:FINGERPRINT + * + * Note that "PRINCIPAL" can contain whitespace, "RSA" and + * "SHA256" part could be a different token that names of + * the algorithms used, and "FINGERPRINT" is a hexadecimal + * string. By finding the last occurence of " with ", we can + * reliably parse out the PRINCIPAL. + */ + sigc->result = 'B'; + sigc->trust_level = TRUST_NEVER; + + line = to_free = xmemdupz(sigc->output, strcspn(sigc->output, "\n")); + + if (skip_prefix(line, "Good \"git\" signature for ", &line)) { + /* Search for the last "with" to get the full principal */ + principal = line; + do { + search = strstr(line, " with "); + if (search) + line = search + 1; + } while (search != NULL); + if (line == principal) + goto cleanup; + + /* Valid signature and known principal */ + sigc->result = 'G'; + sigc->trust_level = TRUST_FULLY; + sigc->signer = xmemdupz(principal, line - principal - 1); + } else if (skip_prefix(line, "Good \"git\" signature with ", &line)) { + /* Valid signature, but key unknown */ + sigc->result = 'G'; + sigc->trust_level = TRUST_UNDEFINED; + } else { + goto cleanup; + } + + key = strstr(line, "key "); + if (key) { + sigc->fingerprint = xstrdup(strstr(line, "key ") + 4); + sigc->key = xstrdup(sigc->fingerprint); + } else { + /* + * Output did not match what we expected + * Treat the signature as bad + */ + sigc->result = 'B'; + } + +cleanup: + free(to_free); +} + +static int verify_ssh_signed_buffer(struct signature_check *sigc, + struct gpg_format *fmt, const char *payload, + size_t payload_size, const char *signature, + size_t signature_size) +{ + struct child_process ssh_keygen = CHILD_PROCESS_INIT; + struct tempfile *buffer_file; + int ret = -1; + const char *line; + size_t trust_size; + char *principal; + struct strbuf ssh_principals_out = STRBUF_INIT; + struct strbuf ssh_principals_err = STRBUF_INIT; + struct strbuf ssh_keygen_out = STRBUF_INIT; + struct strbuf ssh_keygen_err = STRBUF_INIT; + + if (!ssh_allowed_signers) { + error(_("gpg.ssh.allowedSignersFile needs to be configured and exist for ssh signature verification")); + return -1; + } + + buffer_file = mks_tempfile_t(".git_vtag_tmpXXXXXX"); + if (!buffer_file) + return error_errno(_("could not create temporary file")); + if (write_in_full(buffer_file->fd, signature, signature_size) < 0 || + close_tempfile_gently(buffer_file) < 0) { + error_errno(_("failed writing detached signature to '%s'"), + buffer_file->filename.buf); + delete_tempfile(&buffer_file); + return -1; + } + + /* Find the principal from the signers */ + strvec_pushl(&ssh_keygen.args, fmt->program, + "-Y", "find-principals", + "-f", ssh_allowed_signers, + "-s", buffer_file->filename.buf, + NULL); + ret = pipe_command(&ssh_keygen, NULL, 0, &ssh_principals_out, 0, + &ssh_principals_err, 0); + if (ret && strstr(ssh_principals_err.buf, "usage:")) { + error(_("ssh-keygen -Y find-principals/verify is needed for ssh signature verification (available in openssh version 8.2p1+)")); + goto out; + } + if (ret || !ssh_principals_out.len) { + /* + * We did not find a matching principal in the allowedSigners + * Check without validation + */ + child_process_init(&ssh_keygen); + strvec_pushl(&ssh_keygen.args, fmt->program, + "-Y", "check-novalidate", + "-n", "git", + "-s", buffer_file->filename.buf, + NULL); + pipe_command(&ssh_keygen, payload, payload_size, + &ssh_keygen_out, 0, &ssh_keygen_err, 0); + + /* + * Fail on unknown keys + * we still call check-novalidate to display the signature info + */ + ret = -1; + } else { + /* Check every principal we found (one per line) */ + for (line = ssh_principals_out.buf; *line; + line = strchrnul(line + 1, '\n')) { + while (*line == '\n') + line++; + if (!*line) + break; + + trust_size = strcspn(line, "\n"); + principal = xmemdupz(line, trust_size); + + child_process_init(&ssh_keygen); + strbuf_release(&ssh_keygen_out); + strbuf_release(&ssh_keygen_err); + strvec_push(&ssh_keygen.args, fmt->program); + /* + * We found principals + * Try with each until we find a match + */ + strvec_pushl(&ssh_keygen.args, "-Y", "verify", + "-n", "git", + "-f", ssh_allowed_signers, + "-I", principal, + "-s", buffer_file->filename.buf, + NULL); + + if (ssh_revocation_file) { + if (file_exists(ssh_revocation_file)) { + strvec_pushl(&ssh_keygen.args, "-r", + ssh_revocation_file, NULL); + } else { + warning(_("ssh signing revocation file configured but not found: %s"), + ssh_revocation_file); + } + } + + sigchain_push(SIGPIPE, SIG_IGN); + ret = pipe_command(&ssh_keygen, payload, payload_size, + &ssh_keygen_out, 0, &ssh_keygen_err, 0); + sigchain_pop(SIGPIPE); + + FREE_AND_NULL(principal); + + if (!ret) + ret = !starts_with(ssh_keygen_out.buf, "Good"); + + if (!ret) + break; + } + } + + sigc->payload = xmemdupz(payload, payload_size); + strbuf_stripspace(&ssh_keygen_out, 0); + strbuf_stripspace(&ssh_keygen_err, 0); + /* Add stderr outputs to show the user actual ssh-keygen errors */ + strbuf_add(&ssh_keygen_out, ssh_principals_err.buf, ssh_principals_err.len); + strbuf_add(&ssh_keygen_out, ssh_keygen_err.buf, ssh_keygen_err.len); + sigc->output = strbuf_detach(&ssh_keygen_out, NULL); + sigc->gpg_status = xstrdup(sigc->output); + + parse_ssh_output(sigc); + +out: + if (buffer_file) + delete_tempfile(&buffer_file); + strbuf_release(&ssh_principals_out); + strbuf_release(&ssh_principals_err); + strbuf_release(&ssh_keygen_out); + strbuf_release(&ssh_keygen_err); return ret; } @@ -309,35 +565,32 @@ static int verify_signed_buffer(const char *payload, size_t payload_size, int check_signature(const char *payload, size_t plen, const char *signature, size_t slen, struct signature_check *sigc) { - struct strbuf gpg_output = STRBUF_INIT; - struct strbuf gpg_status = STRBUF_INIT; + struct gpg_format *fmt; int status; sigc->result = 'N'; sigc->trust_level = -1; - status = verify_signed_buffer(payload, plen, signature, slen, - &gpg_output, &gpg_status); - if (status && !gpg_output.len) - goto out; - sigc->payload = xmemdupz(payload, plen); - sigc->gpg_output = strbuf_detach(&gpg_output, NULL); - sigc->gpg_status = strbuf_detach(&gpg_status, NULL); - parse_gpg_output(sigc); + fmt = get_format_by_sig(signature); + if (!fmt) + die(_("bad/incompatible signature '%s'"), signature); + + status = fmt->verify_signed_buffer(sigc, fmt, payload, plen, signature, + slen); + + if (status && !sigc->output) + return !!status; + status |= sigc->result != 'G'; status |= sigc->trust_level < configured_min_trust_level; - out: - strbuf_release(&gpg_status); - strbuf_release(&gpg_output); - return !!status; } void print_signature_buffer(const struct signature_check *sigc, unsigned flags) { - const char *output = flags & GPG_VERIFY_RAW ? - sigc->gpg_status : sigc->gpg_output; + const char *output = flags & GPG_VERIFY_RAW ? sigc->gpg_status : + sigc->output; if (flags & GPG_VERIFY_VERBOSE && sigc->payload) fputs(sigc->payload, stdout); @@ -419,12 +672,33 @@ int git_gpg_config(const char *var, const char *value, void *cb) return 0; } + if (!strcmp(var, "gpg.ssh.defaultkeycommand")) { + if (!value) + return config_error_nonbool(var); + return git_config_string(&ssh_default_key_command, var, value); + } + + if (!strcmp(var, "gpg.ssh.allowedsignersfile")) { + if (!value) + return config_error_nonbool(var); + return git_config_pathname(&ssh_allowed_signers, var, value); + } + + if (!strcmp(var, "gpg.ssh.revocationfile")) { + if (!value) + return config_error_nonbool(var); + return git_config_pathname(&ssh_revocation_file, var, value); + } + if (!strcmp(var, "gpg.program") || !strcmp(var, "gpg.openpgp.program")) fmtname = "openpgp"; if (!strcmp(var, "gpg.x509.program")) fmtname = "x509"; + if (!strcmp(var, "gpg.ssh.program")) + fmtname = "ssh"; + if (fmtname) { fmt = get_format_by_name(fmtname); return git_config_string(&fmt->program, var, value); @@ -433,18 +707,148 @@ int git_gpg_config(const char *var, const char *value, void *cb) return 0; } +static char *get_ssh_key_fingerprint(const char *signing_key) +{ + struct child_process ssh_keygen = CHILD_PROCESS_INIT; + int ret = -1; + struct strbuf fingerprint_stdout = STRBUF_INIT; + struct strbuf **fingerprint; + char *fingerprint_ret; + + /* + * With SSH Signing this can contain a filename or a public key + * For textual representation we usually want a fingerprint + */ + if (starts_with(signing_key, "ssh-")) { + strvec_pushl(&ssh_keygen.args, "ssh-keygen", "-lf", "-", NULL); + ret = pipe_command(&ssh_keygen, signing_key, + strlen(signing_key), &fingerprint_stdout, 0, + NULL, 0); + } else { + strvec_pushl(&ssh_keygen.args, "ssh-keygen", "-lf", + configured_signing_key, NULL); + ret = pipe_command(&ssh_keygen, NULL, 0, &fingerprint_stdout, 0, + NULL, 0); + } + + if (!!ret) + die_errno(_("failed to get the ssh fingerprint for key '%s'"), + signing_key); + + fingerprint = strbuf_split_max(&fingerprint_stdout, ' ', 3); + if (!fingerprint[1]) + die_errno(_("failed to get the ssh fingerprint for key '%s'"), + signing_key); + + fingerprint_ret = strbuf_detach(fingerprint[1], NULL); + strbuf_list_free(fingerprint); + strbuf_release(&fingerprint_stdout); + return fingerprint_ret; +} + +/* Returns the first public key from an ssh-agent to use for signing */ +static const char *get_default_ssh_signing_key(void) +{ + struct child_process ssh_default_key = CHILD_PROCESS_INIT; + int ret = -1; + struct strbuf key_stdout = STRBUF_INIT, key_stderr = STRBUF_INIT; + struct strbuf **keys; + char *key_command = NULL; + const char **argv; + int n; + char *default_key = NULL; + + if (!ssh_default_key_command) + die(_("either user.signingkey or gpg.ssh.defaultKeyCommand needs to be configured")); + + key_command = xstrdup(ssh_default_key_command); + n = split_cmdline(key_command, &argv); + + if (n < 0) + die("malformed build-time gpg.ssh.defaultKeyCommand: %s", + split_cmdline_strerror(n)); + + strvec_pushv(&ssh_default_key.args, argv); + ret = pipe_command(&ssh_default_key, NULL, 0, &key_stdout, 0, + &key_stderr, 0); + + if (!ret) { + keys = strbuf_split_max(&key_stdout, '\n', 2); + if (keys[0] && starts_with(keys[0]->buf, "ssh-")) { + default_key = strbuf_detach(keys[0], NULL); + } else { + warning(_("gpg.ssh.defaultKeyCommand succeeded but returned no keys: %s %s"), + key_stderr.buf, key_stdout.buf); + } + + strbuf_list_free(keys); + } else { + warning(_("gpg.ssh.defaultKeyCommand failed: %s %s"), + key_stderr.buf, key_stdout.buf); + } + + free(key_command); + free(argv); + strbuf_release(&key_stdout); + + return default_key; +} + +static const char *get_ssh_key_id(void) { + return get_ssh_key_fingerprint(get_signing_key()); +} + +/* Returns a textual but unique representation of the signing key */ +const char *get_signing_key_id(void) +{ + if (use_format->get_key_id) { + return use_format->get_key_id(); + } + + /* GPG/GPGSM only store a key id on this variable */ + return get_signing_key(); +} + const char *get_signing_key(void) { if (configured_signing_key) return configured_signing_key; - return git_committer_info(IDENT_STRICT|IDENT_NO_DATE); + if (use_format->get_default_key) { + return use_format->get_default_key(); + } + + return git_committer_info(IDENT_STRICT | IDENT_NO_DATE); } int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key) { + return use_format->sign_buffer(buffer, signature, signing_key); +} + +/* + * Strip CR from the line endings, in case we are on Windows. + * NEEDSWORK: make it trim only CRs before LFs and rename + */ +static void remove_cr_after(struct strbuf *buffer, size_t offset) +{ + size_t i, j; + + for (i = j = offset; i < buffer->len; i++) { + if (buffer->buf[i] != '\r') { + if (i != j) + buffer->buf[j] = buffer->buf[i]; + j++; + } + } + strbuf_setlen(buffer, j); +} + +static int sign_buffer_gpg(struct strbuf *buffer, struct strbuf *signature, + const char *signing_key) +{ struct child_process gpg = CHILD_PROCESS_INIT; int ret; - size_t i, j, bottom; + size_t bottom; struct strbuf gpg_status = STRBUF_INIT; strvec_pushl(&gpg.args, @@ -470,13 +874,98 @@ int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *sig return error(_("gpg failed to sign the data")); /* Strip CR from the line endings, in case we are on Windows. */ - for (i = j = bottom; i < signature->len; i++) - if (signature->buf[i] != '\r') { - if (i != j) - signature->buf[j] = signature->buf[i]; - j++; - } - strbuf_setlen(signature, j); + remove_cr_after(signature, bottom); return 0; } + +static int sign_buffer_ssh(struct strbuf *buffer, struct strbuf *signature, + const char *signing_key) +{ + struct child_process signer = CHILD_PROCESS_INIT; + int ret = -1; + size_t bottom, keylen; + struct strbuf signer_stderr = STRBUF_INIT; + struct tempfile *key_file = NULL, *buffer_file = NULL; + char *ssh_signing_key_file = NULL; + struct strbuf ssh_signature_filename = STRBUF_INIT; + + if (!signing_key || signing_key[0] == '\0') + return error( + _("user.signingkey needs to be set for ssh signing")); + + if (starts_with(signing_key, "ssh-")) { + /* A literal ssh key */ + key_file = mks_tempfile_t(".git_signing_key_tmpXXXXXX"); + if (!key_file) + return error_errno( + _("could not create temporary file")); + keylen = strlen(signing_key); + if (write_in_full(key_file->fd, signing_key, keylen) < 0 || + close_tempfile_gently(key_file) < 0) { + error_errno(_("failed writing ssh signing key to '%s'"), + key_file->filename.buf); + goto out; + } + ssh_signing_key_file = strbuf_detach(&key_file->filename, NULL); + } else { + /* We assume a file */ + ssh_signing_key_file = expand_user_path(signing_key, 1); + } + + buffer_file = mks_tempfile_t(".git_signing_buffer_tmpXXXXXX"); + if (!buffer_file) { + error_errno(_("could not create temporary file")); + goto out; + } + + if (write_in_full(buffer_file->fd, buffer->buf, buffer->len) < 0 || + close_tempfile_gently(buffer_file) < 0) { + error_errno(_("failed writing ssh signing key buffer to '%s'"), + buffer_file->filename.buf); + goto out; + } + + strvec_pushl(&signer.args, use_format->program, + "-Y", "sign", + "-n", "git", + "-f", ssh_signing_key_file, + buffer_file->filename.buf, + NULL); + + sigchain_push(SIGPIPE, SIG_IGN); + ret = pipe_command(&signer, NULL, 0, NULL, 0, &signer_stderr, 0); + sigchain_pop(SIGPIPE); + + if (ret) { + if (strstr(signer_stderr.buf, "usage:")) + error(_("ssh-keygen -Y sign is needed for ssh signing (available in openssh version 8.2p1+)")); + + error("%s", signer_stderr.buf); + goto out; + } + + bottom = signature->len; + + strbuf_addbuf(&ssh_signature_filename, &buffer_file->filename); + strbuf_addstr(&ssh_signature_filename, ".sig"); + if (strbuf_read_file(signature, ssh_signature_filename.buf, 0) < 0) { + error_errno( + _("failed reading ssh signing data buffer from '%s'"), + ssh_signature_filename.buf); + } + unlink_or_warn(ssh_signature_filename.buf); + + /* Strip CR from the line endings, in case we are on Windows. */ + remove_cr_after(signature, bottom); + +out: + if (key_file) + delete_tempfile(&key_file); + if (buffer_file) + delete_tempfile(&buffer_file); + strbuf_release(&signer_stderr); + strbuf_release(&ssh_signature_filename); + FREE_AND_NULL(ssh_signing_key_file); + return ret; +} |