Mercurial > dropbear
view signkey_ossh.c @ 1930:299f4f19ba19
Add /usr/sbin and /sbin to default root PATH
When dropbear is used in a very restricted environment (such as in a
initrd), the default user shell is often also very restricted
and doesn't take care of setting the PATH so the user ends up
with the PATH set by dropbear. Unfortunately, dropbear always
sets "/usr/bin:/bin" as default PATH even for the root user
which should have /usr/sbin and /sbin too.
For a concrete instance of this problem, see the "Remote Unlocking"
section in this tutorial: https://paxswill.com/blog/2013/11/04/encrypted-raspberry-pi/
It speaks of a bug in the initramfs script because it's written "blkid"
instead of "/sbin/blkid"... this is just because the scripts from the
initramfs do not expect to have a PATH without the sbin directories and
because dropbear is not setting the PATH appropriately for the root user.
I'm thus suggesting to use the attached patch to fix this misbehaviour (I
did not test it, but it's easy enough). It might seem anecdotic but
multiple Kali users have been bitten by this.
From https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=903403
author | Raphael Hertzog <hertzog@debian.org> |
---|---|
date | Mon, 09 Jul 2018 16:27:53 +0200 |
parents | ced53051e200 |
children |
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#include "includes.h" #include "dbutil.h" #include "ssh.h" #include "signkey_ossh.h" #include "bignum.h" #include "ecdsa.h" #include "sk-ecdsa.h" #include "sk-ed25519.h" #include "rsa.h" #include "dss.h" #include "ed25519.h" #if DROPBEAR_RSA /* OpenSSH raw private RSA format is string "ssh-rsa" mpint n mpint e mpint d mpint iqmp (q^-1) mod p mpint p mpint q */ void buf_put_rsa_priv_ossh(buffer *buf, const sign_key *akey) { const dropbear_rsa_key *key = akey->rsakey; mp_int iqmp; dropbear_assert(key != NULL); if (!(key->p && key->q)) { dropbear_exit("Pre-0.33 Dropbear keys cannot be converted to OpenSSH keys.\n"); } m_mp_init(&iqmp); /* iqmp = (q^-1) mod p */ if (mp_invmod(key->q, key->p, &iqmp) != MP_OKAY) { dropbear_exit("Bignum error for iqmp\n"); } buf_putstring(buf, SSH_SIGNKEY_RSA, SSH_SIGNKEY_RSA_LEN); buf_putmpint(buf, key->n); buf_putmpint(buf, key->e); buf_putmpint(buf, key->d); buf_putmpint(buf, &iqmp); buf_putmpint(buf, key->p); buf_putmpint(buf, key->q); mp_clear(&iqmp); } int buf_get_rsa_priv_ossh(buffer *buf, sign_key *akey) { int ret = DROPBEAR_FAILURE; dropbear_rsa_key *key = NULL; mp_int iqmp; rsa_key_free(akey->rsakey); akey->rsakey = m_malloc(sizeof(*akey->rsakey)); key = akey->rsakey; m_mp_alloc_init_multi(&key->e, &key->n, &key->d, &key->p, &key->q, NULL); buf_eatstring(buf); m_mp_init(&iqmp); if (buf_getmpint(buf, key->n) == DROPBEAR_SUCCESS && buf_getmpint(buf, key->e) == DROPBEAR_SUCCESS && buf_getmpint(buf, key->d) == DROPBEAR_SUCCESS && buf_getmpint(buf, &iqmp) == DROPBEAR_SUCCESS && buf_getmpint(buf, key->p) == DROPBEAR_SUCCESS && buf_getmpint(buf, key->q) == DROPBEAR_SUCCESS) { ret = DROPBEAR_SUCCESS; } mp_clear(&iqmp); return ret; } #endif /* DROPBEAR_RSA */ #if DROPBEAR_ED25519 /* OpenSSH raw private ed25519 format is string "ssh-ed25519" uint32 32 byte[32] pubkey uint32 64 byte[32] privkey byte[32] pubkey */ void buf_put_ed25519_priv_ossh(buffer *buf, const sign_key *akey) { const dropbear_ed25519_key *key = akey->ed25519key; dropbear_assert(key != NULL); buf_putstring(buf, SSH_SIGNKEY_ED25519, SSH_SIGNKEY_ED25519_LEN); buf_putint(buf, CURVE25519_LEN); buf_putbytes(buf, key->pub, CURVE25519_LEN); buf_putint(buf, CURVE25519_LEN*2); buf_putbytes(buf, key->priv, CURVE25519_LEN); buf_putbytes(buf, key->pub, CURVE25519_LEN); } int buf_get_ed25519_priv_ossh(buffer *buf, sign_key *akey) { dropbear_ed25519_key *key = NULL; uint32_t len; ed25519_key_free(akey->ed25519key); akey->ed25519key = m_malloc(sizeof(*akey->ed25519key)); key = akey->ed25519key; /* Parse past the first string and pubkey */ if (buf_get_ed25519_pub_key(buf, key, DROPBEAR_SIGNKEY_ED25519) == DROPBEAR_FAILURE) { dropbear_log(LOG_ERR, "Error parsing ed25519 key, pubkey"); return DROPBEAR_FAILURE; } len = buf_getint(buf); if (len != 2*CURVE25519_LEN) { dropbear_log(LOG_ERR, "Error parsing ed25519 key, bad length"); return DROPBEAR_FAILURE; } memcpy(key->priv, buf_getptr(buf, CURVE25519_LEN), CURVE25519_LEN); buf_incrpos(buf, CURVE25519_LEN); /* Sanity check */ if (memcmp(buf_getptr(buf, CURVE25519_LEN), key->pub, CURVE25519_LEN) != 0) { dropbear_log(LOG_ERR, "Error parsing ed25519 key, mismatch pubkey"); return DROPBEAR_FAILURE; } return DROPBEAR_SUCCESS; } #endif /* DROPBEAR_ED255219 */ #if DROPBEAR_ECDSA /* OpenSSH raw private ecdsa format is the same as Dropbear's. # First part is the same as the SSH wire pubkey format string "ecdsa-sha2-[identifier]" string [identifier] string Q # With private part appended mpint d */ void buf_put_ecdsa_priv_ossh(buffer *buf, const sign_key *key) { ecc_key **eck = (ecc_key**)signkey_key_ptr((sign_key*)key, key->type); if (eck && *eck) { buf_put_ecdsa_priv_key(buf, *eck); return; } dropbear_exit("ecdsa key is not set"); } int buf_get_ecdsa_priv_ossh(buffer *buf, sign_key *key) { ecc_key **eck = (ecc_key**)signkey_key_ptr(key, key->type); if (eck) { if (*eck) { ecc_free(*eck); m_free(*eck); *eck = NULL; } *eck = buf_get_ecdsa_priv_key(buf); if (*eck) { return DROPBEAR_SUCCESS; } } return DROPBEAR_FAILURE; } #endif /* DROPBEAR_ECDSA */