diff options
| author | Damien Miller <djm@cvs.openbsd.org> | 2024-08-20 03:48:31 +0000 |
|---|---|---|
| committer | Damien Miller <djm@cvs.openbsd.org> | 2024-08-20 03:48:31 +0000 |
| commit | 082fdcdf76c1b46c025670b164273d55f2dcab54 (patch) | |
| tree | 2b54c3520be482a4d0dd39cd2d40c6c14a5aa090 | |
| parent | 57a763053ec7ae676939a0f27576ff1a74bc842c (diff) | |
place shielded keys (i.e. keys at rest in RAM) into memory allocated
using mmap(3) with MAP_CONCEAL set. This prevents exposure of the
key material in coredumps, etc (this is in addition to other measures
we take in this area).
ok deraadt@
| -rw-r--r-- | usr.bin/ssh/sshkey.c | 32 |
1 files changed, 26 insertions, 6 deletions
diff --git a/usr.bin/ssh/sshkey.c b/usr.bin/ssh/sshkey.c index ef9c8584519..2727aacbd39 100644 --- a/usr.bin/ssh/sshkey.c +++ b/usr.bin/ssh/sshkey.c @@ -1,4 +1,4 @@ -/* $OpenBSD: sshkey.c,v 1.143 2024/08/15 00:51:51 djm Exp $ */ +/* $OpenBSD: sshkey.c,v 1.144 2024/08/20 03:48:30 djm Exp $ */ /* * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. * Copyright (c) 2008 Alexander von Gernler. All rights reserved. @@ -26,6 +26,7 @@ */ #include <sys/types.h> +#include <sys/mman.h> #include <netinet/in.h> #ifdef WITH_OPENSSL @@ -710,6 +711,27 @@ sshkey_sk_cleanup(struct sshkey *k) k->sk_key_handle = k->sk_reserved = NULL; } +static int +sshkey_prekey_alloc(u_char **prekeyp, size_t len) +{ + u_char *prekey; + + *prekeyp = NULL; + if ((prekey = mmap(NULL, SSHKEY_SHIELD_PREKEY_LEN, PROT_READ|PROT_WRITE, + MAP_ANON|MAP_PRIVATE|MAP_CONCEAL, -1, 0)) == MAP_FAILED) + return SSH_ERR_SYSTEM_ERROR; + *prekeyp = prekey; + return 0; +} + +static void +sshkey_prekey_free(void *prekey, size_t len) +{ + if (prekey == NULL) + return; + munmap(prekey, len); +} + static void sshkey_free_contents(struct sshkey *k) { @@ -723,7 +745,7 @@ sshkey_free_contents(struct sshkey *k) if (sshkey_is_cert(k)) cert_free(k->cert); freezero(k->shielded_private, k->shielded_len); - freezero(k->shield_prekey, k->shield_prekey_len); + sshkey_prekey_free(k->shield_prekey, k->shield_prekey_len); } void @@ -1591,10 +1613,8 @@ sshkey_shield_private(struct sshkey *k) } /* Prepare a random pre-key, and from it an ephemeral key */ - if ((prekey = malloc(SSHKEY_SHIELD_PREKEY_LEN)) == NULL) { - r = SSH_ERR_ALLOC_FAIL; + if ((r = sshkey_prekey_alloc(&prekey, SSHKEY_SHIELD_PREKEY_LEN)) != 0) goto out; - } arc4random_buf(prekey, SSHKEY_SHIELD_PREKEY_LEN); if ((r = ssh_digest_memory(SSHKEY_SHIELD_PREKEY_HASH, prekey, SSHKEY_SHIELD_PREKEY_LEN, @@ -1672,7 +1692,7 @@ sshkey_shield_private(struct sshkey *k) explicit_bzero(keyiv, sizeof(keyiv)); explicit_bzero(&tmp, sizeof(tmp)); freezero(enc, enclen); - freezero(prekey, SSHKEY_SHIELD_PREKEY_LEN); + sshkey_prekey_free(prekey, SSHKEY_SHIELD_PREKEY_LEN); sshkey_free(kswap); sshbuf_free(prvbuf); return r; |