libbb: add optionl support for SHA256/512 encrypted passwords

function                                             old     new   delta
sha_crypt                                              -    2423   +2423
cryptpw_main                                         128     183     +55
to64                                                   -      29     +29
pw_encrypt                                           974    1000     +26
str_rounds                                             -      11     +11
login_main                                          1532    1541      +9
packed_usage                                       25215   25200     -15
__md5_to64                                            29       -     -29
------------------------------------------------------------------------------
(add/remove: 3/1 grow/shrink: 3/1 up/down: 2553/-44)         Total: 2509 bytes

1 files changed, 13 insertions, 1 deletions

diff --git a/loginutils/Config.in b/loginutils/Config.in
index bb1369cdd..5f66e8685 100644
--- a/loginutils/Config.in
+++ b/loginutils/Config.in
@@ -58,7 +58,7 @@ config USE_BB_SHADOW
           password servers and whatnot.
 
 config USE_BB_CRYPT
-        bool "Use internal DES and MD5 crypt functions"
+        bool "Use internal crypt functions"
         default y
         help
           Busybox has internal DES and MD5 crypt functions.
@@ -79,6 +79,18 @@ config USE_BB_CRYPT
           In static build, it makes code _smaller_ by about 1.2k,
           and likely many kilobytes less of bss.
 
+config USE_BB_CRYPT_SHA
+        bool "Enable SHA256/512 crypt functions"
+        default n
+        depends on USE_BB_CRYPT
+        help
+          Enable this if you have passwords starting with "$5$" or "$6$"
+          in your /etc/passwd or /etc/shadow files. These passwords
+          are hashed using SHA256 and SHA512 algorithms. Support for them
+          was added to glibc in 2008.
+          With this option off, login will fail password check for any
+          user which has password encrypted with these algorithms.
+
 config ADDGROUP
         bool "addgroup"
         default n