Date: Fri, 21 Jul 2023 16:36:52 GMT From: Ed Maste <emaste@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 56749f05dbfd - stable/12 - ssh: disallow loading PKCS#11 modules by default Message-ID: <202307211636.36LGaqd6008636@gitrepo.freebsd.org>
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The branch stable/12 has been updated by emaste: URL: https://cgit.FreeBSD.org/src/commit/?id=56749f05dbfdb003aeb5639ef5f9b8af8f5e65ba commit 56749f05dbfdb003aeb5639ef5f9b8af8f5e65ba Author: Ed Maste <emaste@FreeBSD.org> AuthorDate: 2023-07-19 17:02:33 +0000 Commit: Ed Maste <emaste@FreeBSD.org> CommitDate: 2023-07-21 16:25:51 +0000 ssh: disallow loading PKCS#11 modules by default This is the rest of the OpenSSH 9.3p2 change to address CVE-2023-38408. From the release notes: * ssh-agent(8): the agent will now refuse requests to load PKCS#11 modules issued by remote clients by default. A flag has been added to restore the previous behaviour "-Oallow-remote-pkcs11". Note that ssh-agent(8) depends on the SSH client to identify requests that are remote. The OpenSSH >=8.9 ssh(1) client does this, but forwarding access to an agent socket using other tools may circumvent this restriction. Security: CVE-2023-38408 Sponsored by: The FreeBSD Foundation --- crypto/openssh/ssh-agent.1 | 22 ++++++++++++++++++++-- crypto/openssh/ssh-agent.c | 21 ++++++++++++++++++++- 2 files changed, 40 insertions(+), 3 deletions(-) diff --git a/crypto/openssh/ssh-agent.1 b/crypto/openssh/ssh-agent.1 index b9d28b8e103e..a0ea506bdc93 100644 --- a/crypto/openssh/ssh-agent.1 +++ b/crypto/openssh/ssh-agent.1 @@ -108,9 +108,27 @@ environment variable). .It Fl O Ar option Specify an option when starting .Nm . -Currently only one option is supported: +Currently two options are supported: +.Cm allow-remote-pkcs11 +and .Cm no-restrict-websafe . -This instructs +.Pp +The +.Cm allow-remote-pkcs11 +option allows clients of a forwarded +.Nm +to load PKCS#11 or FIDO provider libraries. +By default only local clients may perform this operation. +Note that signalling that a +.Nm +client remote is performed by +.Xr ssh 1 , +and use of other tools to forward access to the agent socket may circumvent +this restriction. +.Pp +The +.Cm no-restrict-websafe , +instructs .Nm to permit signatures using FIDO keys that might be web authentication requests. diff --git a/crypto/openssh/ssh-agent.c b/crypto/openssh/ssh-agent.c index 9f376f83a798..0e218390a21c 100644 --- a/crypto/openssh/ssh-agent.c +++ b/crypto/openssh/ssh-agent.c @@ -172,6 +172,12 @@ char socket_dir[PATH_MAX]; /* Pattern-list of allowed PKCS#11/Security key paths */ static char *allowed_providers; +/* + * Allows PKCS11 providers or SK keys that use non-internal providers to + * be added over a remote connection (identified by session-bind@openssh.com). + */ +static int remote_add_provider; + /* locking */ #define LOCK_SIZE 32 #define LOCK_SALT_SIZE 16 @@ -1249,6 +1255,12 @@ process_add_identity(SocketEntry *e) if (strcasecmp(sk_provider, "internal") == 0) { debug_f("internal provider"); } else { + if (e->nsession_ids != 0 && !remote_add_provider) { + verbose("failed add of SK provider \"%.100s\": " + "remote addition of providers is disabled", + sk_provider); + goto out; + } if (realpath(sk_provider, canonical_provider) == NULL) { verbose("failed provider \"%.100s\": " "realpath: %s", sk_provider, @@ -1412,6 +1424,11 @@ process_add_smartcard_key(SocketEntry *e) error_f("failed to parse constraints"); goto send; } + if (e->nsession_ids != 0 && !remote_add_provider) { + verbose("failed PKCS#11 add of \"%.100s\": remote addition of " + "providers is disabled", provider); + goto send; + } if (realpath(provider, canonical_provider) == NULL) { verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", provider, strerror(errno)); @@ -2077,7 +2094,9 @@ main(int ac, char **av) break; case 'O': if (strcmp(optarg, "no-restrict-websafe") == 0) - restrict_websafe = 0; + restrict_websafe = 0; + else if (strcmp(optarg, "allow-remote-pkcs11") == 0) + remote_add_provider = 1; else fatal("Unknown -O option"); break;
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