diff options
Diffstat (limited to 'gnu/packages/patches/openssh-CVE-2016-6210-2.patch')
| -rw-r--r-- | gnu/packages/patches/openssh-CVE-2016-6210-2.patch | 111 |
1 files changed, 0 insertions, 111 deletions
diff --git a/gnu/packages/patches/openssh-CVE-2016-6210-2.patch b/gnu/packages/patches/openssh-CVE-2016-6210-2.patch deleted file mode 100644 index 1c580f90b9..0000000000 --- a/gnu/packages/patches/openssh-CVE-2016-6210-2.patch +++ /dev/null @@ -1,111 +0,0 @@ -From dde63f7f998ac3812a26bbb2c1b2947f24fcd060 Mon Sep 17 00:00:00 2001 -From: Darren Tucker <dtucker@zip.com.au> -Date: Fri, 15 Jul 2016 13:49:44 +1000 -Subject: Mitigate timing of disallowed users PAM logins. - -When sshd decides to not allow a login (eg PermitRootLogin=no) and -it's using PAM, it sends a fake password to PAM so that the timing for -the failure is not noticeably different whether or not the password -is correct. This behaviour can be detected by sending a very long -password string which is slower to hash than the fake password. - -Mitigate by constructing an invalid password that is the same length -as the one from the client and thus takes the same time to hash. -Diff from djm@ - -Origin: upstream, https://anongit.mindrot.org/openssh.git/commit/?id=283b97ff33ea2c641161950849931bd578de6946 -Bug-Debian: https://bugs.debian.org/831902 -Last-Update: 2016-07-22 - -Patch-Name: CVE-2016-6210-2.patch ---- - auth-pam.c | 35 +++++++++++++++++++++++++++++++---- - 1 file changed, 31 insertions(+), 4 deletions(-) - -diff --git a/auth-pam.c b/auth-pam.c -index 8425af1..abd6a5e 100644 ---- a/auth-pam.c -+++ b/auth-pam.c -@@ -232,7 +232,6 @@ static int sshpam_account_status = -1; - static char **sshpam_env = NULL; - static Authctxt *sshpam_authctxt = NULL; - static const char *sshpam_password = NULL; --static char badpw[] = "\b\n\r\177INCORRECT"; - - /* Some PAM implementations don't implement this */ - #ifndef HAVE_PAM_GETENVLIST -@@ -810,12 +809,35 @@ sshpam_query(void *ctx, char **name, char **info, - return (-1); - } - -+/* -+ * Returns a junk password of identical length to that the user supplied. -+ * Used to mitigate timing attacks against crypt(3)/PAM stacks that -+ * vary processing time in proportion to password length. -+ */ -+static char * -+fake_password(const char *wire_password) -+{ -+ const char junk[] = "\b\n\r\177INCORRECT"; -+ char *ret = NULL; -+ size_t i, l = wire_password != NULL ? strlen(wire_password) : 0; -+ -+ if (l >= INT_MAX) -+ fatal("%s: password length too long: %zu", __func__, l); -+ -+ ret = malloc(l + 1); -+ for (i = 0; i < l; i++) -+ ret[i] = junk[i % (sizeof(junk) - 1)]; -+ ret[i] = '\0'; -+ return ret; -+} -+ - /* XXX - see also comment in auth-chall.c:verify_response */ - static int - sshpam_respond(void *ctx, u_int num, char **resp) - { - Buffer buffer; - struct pam_ctxt *ctxt = ctx; -+ char *fake; - - debug2("PAM: %s entering, %u responses", __func__, num); - switch (ctxt->pam_done) { -@@ -836,8 +858,11 @@ sshpam_respond(void *ctx, u_int num, char **resp) - (sshpam_authctxt->pw->pw_uid != 0 || - options.permit_root_login == PERMIT_YES)) - buffer_put_cstring(&buffer, *resp); -- else -- buffer_put_cstring(&buffer, badpw); -+ else { -+ fake = fake_password(*resp); -+ buffer_put_cstring(&buffer, fake); -+ free(fake); -+ } - if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) { - buffer_free(&buffer); - return (-1); -@@ -1181,6 +1206,7 @@ sshpam_auth_passwd(Authctxt *authctxt, const char *password) - { - int flags = (options.permit_empty_passwd == 0 ? - PAM_DISALLOW_NULL_AUTHTOK : 0); -+ char *fake = NULL; - - if (!options.use_pam || sshpam_handle == NULL) - fatal("PAM: %s called when PAM disabled or failed to " -@@ -1196,7 +1222,7 @@ sshpam_auth_passwd(Authctxt *authctxt, const char *password) - */ - if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && - options.permit_root_login != PERMIT_YES)) -- sshpam_password = badpw; -+ sshpam_password = fake = fake_password(password); - - sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, - (const void *)&passwd_conv); -@@ -1206,6 +1232,7 @@ sshpam_auth_passwd(Authctxt *authctxt, const char *password) - - sshpam_err = pam_authenticate(sshpam_handle, flags); - sshpam_password = NULL; -+ free(fake); - if (sshpam_err == PAM_SUCCESS && authctxt->valid) { - debug("PAM: password authentication accepted for %.100s", - authctxt->user); |