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Alternative password shadowing scheme

Home Page: https://www.openwall.com/tcb/

License: Other

Makefile 4.55% C 78.82% Roff 14.44% Shell 2.19%
password shadow shadowing tcb security

tcb's Introduction

The tcb package contains core components of our tcb suite implementing the
alternative password shadowing scheme on Openwall GNU/*/Linux (Owl).  It is
being made available separately from Owl primarily for use by other
distributions.  For more information please refer to:

https://www.openwall.com/tcb/

To compile and use this you either need recent libxcrypt (which adopted the
password hashing API we had introduced in Owl) or our crypt_blowfish patched
into glibc (which is how we had introduced that API originally).

libxcrypt is available at:

https://github.com/besser82/libxcrypt

crypt_blowfish is available at:

https://www.openwall.com/crypt/

tcb's People

Contributors

besser82 avatar ldv-alt avatar solardiz avatar

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Forkers

besser82 ldv-alt

tcb's Issues

Thread-safety

Make -DENABLE_SETFSUGID the default and only implementation, and use the setgroups() direct syscall, so that we don't affect other threads' effective credentials.

As discussed in #14 (comment) @ldv-alt sees "no potential benefits in keeping the non-ENABLE_SETFSUGID variant, and it definitely makes sense to use the setgroups() syscall instead of the glibc function."

Authentication error after activate pam_tcb

Steps taken:

  1. Build shadow 4.13 with the parameters --with-tcb --with-bcrypt --with-yescrypt.
  2. Replaced pam_unix.so with pam_tcb.so in /etc/pam.d/* files:
# Account management.
account required /nix/store/mc3j8gfm9jafs2ywy9xq96whg10fmn3k-tcb-1.2/lib/security/pam_tcb.so shadow fork helper=/run/wrappers/bin/tcb_chkpwd

# Authentication management.
auth sufficient /nix/store/mc3j8gfm9jafs2ywy9xq96whg10fmn3k-tcb-1.2/lib/security/pam_tcb.so nullok shadow fork helper=/run/wrappers/bin/tcb_chkpwd
auth required pam_deny.so

# Password management.
password sufficient /nix/store/mc3j8gfm9jafs2ywy9xq96whg10fmn3k-tcb-1.2/lib/security/pam_tcb.so use_authtok shadow fork nullok write_to=tcb helper=/run/wrappers/bin/tcb_chkpwd

# Session management.
session required pam_env.so conffile=/etc/pam/environment readenv=0
session required /nix/store/mc3j8gfm9jafs2ywy9xq96whg10fmn3k-tcb-1.2/lib/security/pam_tcb.so helper=/run/wrappers/bin/tcb_chkpwd
  1. Changed permissions for passwd and tcb_chkpwd:
-r-x--s--x 1 root shadow 17K Dec  4 21:59 /run/wrappers/bin/passwd
-r-x--s--x 1 root shadow 17K Dec  4 21:59 /run/wrappers/bin/tcb_chkpwd
  1. Changed file /etc/nsswitch.conf:
shadow:    tcb
  1. Added lines in /etc/login.defs:
USE_TCB yes
TCB_AUTH_GROUP yes
  1. Added group auth
  2. Running tcb_convert

After all changes, when I try to log in I get an error:

login[3552]: pam_tcb(login:auth): Credentials for user root unknown
login[3033]: pam_tcb(login:auth): Authentication failed for UNKNOWN USER from (uid=0)

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