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[openssh] 04/04: upstream: ensure that certificate extensions are lexically sorted.
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djm pushed a commit to branch master
in repository openssh.

commit 2d8a3b7e8b0408dfeb933ac5cfd3a58f5bac49af
Author: djm@openbsd.org <djm@openbsd.org>
Date: Mon Aug 3 02:53:51 2020 +0000

upstream: ensure that certificate extensions are lexically sorted.

Previously if the user specified a custom extension then the everything would
be in order except the custom ones. bz3198 ok dtucker markus

OpenBSD-Commit-ID: d97deb90587b06cb227c66ffebb2d9667bf886f0
---
ssh-keygen.c | 152 +++++++++++++++++++++++++++++++++--------------------------
1 file changed, 85 insertions(+), 67 deletions(-)

diff --git a/ssh-keygen.c b/ssh-keygen.c
index 4a27d3bf..cc092368 100644
--- a/ssh-keygen.c
+++ b/ssh-keygen.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-keygen.c,v 1.414 2020/07/15 07:50:46 solene Exp $ */
+/* $OpenBSD: ssh-keygen.c,v 1.415 2020/08/03 02:53:51 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1994 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -133,13 +133,13 @@ static char *certflags_command = NULL;
static char *certflags_src_addr = NULL;

/* Arbitrary extensions specified by user */
-struct cert_userext {
+struct cert_ext {
char *key;
char *val;
int crit;
};
-static struct cert_userext *cert_userext;
-static size_t ncert_userext;
+static struct cert_ext *cert_ext;
+static size_t ncert_ext;

/* Conversion to/from various formats */
enum {
@@ -1601,31 +1601,32 @@ do_change_comment(struct passwd *pw, const char *identity_comment)
}

static void
-add_flag_option(struct sshbuf *c, const char *name)
+cert_ext_add(const char *key, const char *value, int iscrit)
{
- int r;
-
- debug3("%s: %s", __func__, name);
- if ((r = sshbuf_put_cstring(c, name)) != 0 ||
- (r = sshbuf_put_string(c, NULL, 0)) != 0)
- fatal("%s: buffer error: %s", __func__, ssh_err(r));
+ cert_ext = xreallocarray(cert_ext, ncert_ext + 1, sizeof(*cert_ext));
+ cert_ext[ncert_ext].key = xstrdup(key);
+ cert_ext[ncert_ext].val = value == NULL ? NULL : xstrdup(value);
+ cert_ext[ncert_ext].crit = iscrit;
+ ncert_ext++;
}

-static void
-add_string_option(struct sshbuf *c, const char *name, const char *value)
+/* qsort(3) comparison function for certificate extensions */
+static int
+cert_ext_cmp(const void *_a, const void *_b)
{
- struct sshbuf *b;
+ const struct cert_ext *a = (const struct cert_ext *)_a;
+ const struct cert_ext *b = (const struct cert_ext *)_b;
int r;

- debug3("%s: %s=%s", __func__, name, value);
- if ((b = sshbuf_new()) == NULL)
- fatal("%s: sshbuf_new failed", __func__);
- if ((r = sshbuf_put_cstring(b, value)) != 0 ||
- (r = sshbuf_put_cstring(c, name)) != 0 ||
- (r = sshbuf_put_stringb(c, b)) != 0)
- fatal("%s: buffer error: %s", __func__, ssh_err(r));
-
- sshbuf_free(b);
+ if (a->crit != b->crit)
+ return (a->crit < b->crit) ? -1 : 1;
+ if ((r = strcmp(a->key, b->key)) != 0)
+ return r;
+ if ((a->val == NULL) != (b->val == NULL))
+ return (a->val == NULL) ? -1 : 1;
+ if (a->val != NULL && (r = strcmp(a->val, b->val)) != 0)
+ return r;
+ return 0;
}

#define OPTIONS_CRITICAL 1
@@ -1633,44 +1634,62 @@ add_string_option(struct sshbuf *c, const char *name, const char *value)
static void
prepare_options_buf(struct sshbuf *c, int which)
{
+ struct sshbuf *b;
size_t i;
+ int r;
+ const struct cert_ext *ext;

+ if ((b = sshbuf_new()) == NULL)
+ fatal("%s: sshbuf_new failed", __func__);
sshbuf_reset(c);
- if ((which & OPTIONS_CRITICAL) != 0 &&
- certflags_command != NULL)
- add_string_option(c, "force-command", certflags_command);
- if ((which & OPTIONS_EXTENSIONS) != 0 &&
- (certflags_flags & CERTOPT_X_FWD) != 0)
- add_flag_option(c, "permit-X11-forwarding");
- if ((which & OPTIONS_EXTENSIONS) != 0 &&
- (certflags_flags & CERTOPT_AGENT_FWD) != 0)
- add_flag_option(c, "permit-agent-forwarding");
- if ((which & OPTIONS_EXTENSIONS) != 0 &&
- (certflags_flags & CERTOPT_PORT_FWD) != 0)
- add_flag_option(c, "permit-port-forwarding");
- if ((which & OPTIONS_EXTENSIONS) != 0 &&
- (certflags_flags & CERTOPT_PTY) != 0)
- add_flag_option(c, "permit-pty");
- if ((which & OPTIONS_EXTENSIONS) != 0 &&
- (certflags_flags & CERTOPT_USER_RC) != 0)
- add_flag_option(c, "permit-user-rc");
- if ((which & OPTIONS_EXTENSIONS) != 0 &&
- (certflags_flags & CERTOPT_NO_REQUIRE_USER_PRESENCE) != 0)
- add_flag_option(c, "no-touch-required");
- if ((which & OPTIONS_CRITICAL) != 0 &&
- certflags_src_addr != NULL)
- add_string_option(c, "source-address", certflags_src_addr);
- for (i = 0; i < ncert_userext; i++) {
- if ((cert_userext[i].crit && (which & OPTIONS_EXTENSIONS)) ||
- (!cert_userext[i].crit && (which & OPTIONS_CRITICAL)))
+ for (i = 0; i < ncert_ext; i++) {
+ ext = &cert_ext[i];
+ if ((ext->crit && (which & OPTIONS_EXTENSIONS)) ||
+ (!ext->crit && (which & OPTIONS_CRITICAL)))
continue;
- if (cert_userext[i].val == NULL)
- add_flag_option(c, cert_userext[i].key);
- else {
- add_string_option(c, cert_userext[i].key,
- cert_userext[i].val);
+ if (ext->val == NULL) {
+ /* flag option */
+ debug3("%s: %s", __func__, ext->key);
+ if ((r = sshbuf_put_cstring(c, ext->key)) != 0 ||
+ (r = sshbuf_put_string(c, NULL, 0)) != 0)
+ fatal("%s: buffer: %s", __func__, ssh_err(r));
+ } else {
+ /* key/value option */
+ debug3("%s: %s=%s", __func__, ext->key, ext->val);
+ sshbuf_reset(b);
+ if ((r = sshbuf_put_cstring(c, ext->key)) != 0 ||
+ (r = sshbuf_put_cstring(b, ext->val)) != 0 ||
+ (r = sshbuf_put_stringb(c, b)) != 0)
+ fatal("%s: buffer: %s", __func__, ssh_err(r));
}
}
+ sshbuf_free(b);
+}
+
+static void
+finalise_cert_exts(void)
+{
+ /* critical options */
+ if (certflags_command != NULL)
+ cert_ext_add("force-command", certflags_command, 1);
+ if (certflags_src_addr != NULL)
+ cert_ext_add("source-address", certflags_src_addr, 1);
+ /* extensions */
+ if ((certflags_flags & CERTOPT_X_FWD) != 0)
+ cert_ext_add("permit-X11-forwarding", NULL, 0);
+ if ((certflags_flags & CERTOPT_AGENT_FWD) != 0)
+ cert_ext_add("permit-agent-forwarding", NULL, 0);
+ if ((certflags_flags & CERTOPT_PORT_FWD) != 0)
+ cert_ext_add("permit-port-forwarding", NULL, 0);
+ if ((certflags_flags & CERTOPT_PTY) != 0)
+ cert_ext_add("permit-pty", NULL, 0);
+ if ((certflags_flags & CERTOPT_USER_RC) != 0)
+ cert_ext_add("permit-user-rc", NULL, 0);
+ if ((certflags_flags & CERTOPT_NO_REQUIRE_USER_PRESENCE) != 0)
+ cert_ext_add("no-touch-required", NULL, 0);
+ /* order lexically by key */
+ if (ncert_ext > 0)
+ qsort(cert_ext, ncert_ext, sizeof(*cert_ext), cert_ext_cmp);
}

static struct sshkey *
@@ -1780,6 +1799,7 @@ do_ca_sign(struct passwd *pw, const char *ca_key_path, int prefer_agent,
}
ca_fp = sshkey_fingerprint(ca, fingerprint_hash, SSH_FP_DEFAULT);

+ finalise_cert_exts();
for (i = 0; i < argc; i++) {
/* Split list of principals */
n = 0;
@@ -1994,13 +2014,8 @@ add_cert_option(char *opt)
val = xstrdup(strchr(opt, ':') + 1);
if ((cp = strchr(val, '=')) != NULL)
*cp++ = '\0';
- cert_userext = xreallocarray(cert_userext, ncert_userext + 1,
- sizeof(*cert_userext));
- cert_userext[ncert_userext].key = val;
- cert_userext[ncert_userext].val = cp == NULL ?
- NULL : xstrdup(cp);
- cert_userext[ncert_userext].crit = iscrit;
- ncert_userext++;
+ cert_ext_add(val, cp, iscrit);
+ free(val);
} else
fatal("Unsupported certificate option \"%s\"", opt);
}
@@ -2008,7 +2023,7 @@ add_cert_option(char *opt)
static void
show_options(struct sshbuf *optbuf, int in_critical)
{
- char *name, *arg;
+ char *name, *arg, *hex;
struct sshbuf *options, *option = NULL;
int r;

@@ -2037,11 +2052,14 @@ show_options(struct sshbuf *optbuf, int in_critical)
__func__, ssh_err(r));
printf(" %s\n", arg);
free(arg);
- } else {
- printf(" UNKNOWN OPTION (len %zu)\n",
- sshbuf_len(option));
+ } else if (sshbuf_len(option) > 0) {
+ hex = sshbuf_dtob16(option);
+ printf(" UNKNOWN OPTION: %s (len %zu)\n",
+ hex, sshbuf_len(option));
sshbuf_reset(option);
- }
+ free(hex);
+ } else
+ printf(" UNKNOWN FLAG OPTION\n");
free(name);
if (sshbuf_len(option) != 0)
fatal("Option corrupt: extra data at end");

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