diff options
Diffstat (limited to 'gnu/packages/patches/openssh-CVE-2016-6210-1.patch')
| -rw-r--r-- | gnu/packages/patches/openssh-CVE-2016-6210-1.patch | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/gnu/packages/patches/openssh-CVE-2016-6210-1.patch b/gnu/packages/patches/openssh-CVE-2016-6210-1.patch new file mode 100644 index 0000000000..9b46ec12a9 --- /dev/null +++ b/gnu/packages/patches/openssh-CVE-2016-6210-1.patch @@ -0,0 +1,114 @@ +From e5ef9d3942cebda819a6fd81647b51c8d87d23df Mon Sep 17 00:00:00 2001 +From: Darren Tucker <dtucker@zip.com.au> +Date: Fri, 15 Jul 2016 13:32:45 +1000 +Subject: Determine appropriate salt for invalid users. + +When sshd is processing a non-PAM login for a non-existent user it uses +the string from the fakepw structure as the salt for crypt(3)ing the +password supplied by the client. That string has a Blowfish prefix, so on +systems that don't understand that crypt will fail fast due to an invalid +salt, and even on those that do it may have significantly different timing +from the hash methods used for real accounts (eg sha512). This allows +user enumeration by, eg, sending large password strings. This was noted +by EddieEzra.Harari at verint.com (CVE-2016-6210). + +To mitigate, use the same hash algorithm that root uses for hashing +passwords for users that do not exist on the system. ok djm@ + +Origin: upstream, https://anongit.mindrot.org/openssh.git/commit/?id=9286875a73b2de7736b5e50692739d314cd8d9dc +Bug-Debian: https://bugs.debian.org/831902 +Last-Update: 2016-07-22 + +Patch-Name: CVE-2016-6210-1.patch +--- + auth-passwd.c | 12 ++++++++---- + openbsd-compat/xcrypt.c | 34 ++++++++++++++++++++++++++++++++++ + 2 files changed, 42 insertions(+), 4 deletions(-) + +diff --git a/auth-passwd.c b/auth-passwd.c +index 63ccf3c..530b5d4 100644 +--- a/auth-passwd.c ++++ b/auth-passwd.c +@@ -193,7 +193,7 @@ int + sys_auth_passwd(Authctxt *authctxt, const char *password) + { + struct passwd *pw = authctxt->pw; +- char *encrypted_password; ++ char *encrypted_password, *salt = NULL; + + /* Just use the supplied fake password if authctxt is invalid */ + char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd; +@@ -202,9 +202,13 @@ sys_auth_passwd(Authctxt *authctxt, const char *password) + if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0) + return (1); + +- /* Encrypt the candidate password using the proper salt. */ +- encrypted_password = xcrypt(password, +- (pw_password[0] && pw_password[1]) ? pw_password : "xx"); ++ /* ++ * Encrypt the candidate password using the proper salt, or pass a ++ * NULL and let xcrypt pick one. ++ */ ++ if (authctxt->valid && pw_password[0] && pw_password[1]) ++ salt = pw_password; ++ encrypted_password = xcrypt(password, salt); + + /* + * Authentication is accepted if the encrypted passwords +diff --git a/openbsd-compat/xcrypt.c b/openbsd-compat/xcrypt.c +index 8577cbd..8913bb8 100644 +--- a/openbsd-compat/xcrypt.c ++++ b/openbsd-compat/xcrypt.c +@@ -25,6 +25,7 @@ + #include "includes.h" + + #include <sys/types.h> ++#include <string.h> + #include <unistd.h> + #include <pwd.h> + +@@ -62,11 +63,44 @@ + # define crypt DES_crypt + # endif + ++/* ++ * Pick an appropriate password encryption type and salt for the running ++ * system. ++ */ ++static const char * ++pick_salt(void) ++{ ++ struct passwd *pw; ++ char *passwd, *p; ++ size_t typelen; ++ static char salt[32]; ++ ++ if (salt[0] != '\0') ++ return salt; ++ strlcpy(salt, "xx", sizeof(salt)); ++ if ((pw = getpwuid(0)) == NULL) ++ return salt; ++ passwd = shadow_pw(pw); ++ if (passwd[0] != '$' || (p = strrchr(passwd + 1, '$')) == NULL) ++ return salt; /* no $, DES */ ++ typelen = p - passwd + 1; ++ strlcpy(salt, passwd, MIN(typelen, sizeof(salt))); ++ explicit_bzero(passwd, strlen(passwd)); ++ return salt; ++} ++ + char * + xcrypt(const char *password, const char *salt) + { + char *crypted; + ++ /* ++ * If we don't have a salt we are encrypting a fake password for ++ * for timing purposes. Pick an appropriate salt. ++ */ ++ if (salt == NULL) ++ salt = pick_salt(); ++ + # ifdef HAVE_MD5_PASSWORDS + if (is_md5_salt(salt)) + crypted = md5_crypt(password, salt); |