From 0eb0f49c5c32940fd192ef98e0d13bf5407da27b Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Sun, 9 Feb 2014 16:10:06 +0000 Subject: Add DebianBanner server configuration option Setting this to "no" causes sshd to omit the Debian revision from its initial protocol handshake, for those scared by package-versioning.patch. Bug-Debian: http://bugs.debian.org/562048 Forwarded: not-needed Last-Update: 2015-11-29 Patch-Name: debian-banner.patch --- servconf.c | 9 +++++++++ servconf.h | 2 ++ sshd.c | 3 ++- sshd_config.5 | 5 +++++ 4 files changed, 18 insertions(+), 1 deletion(-) diff --git a/servconf.c b/servconf.c index ca73f7c5..a391cf4b 100644 --- a/servconf.c +++ b/servconf.c @@ -166,6 +166,7 @@ initialize_server_options(ServerOptions *options) options->version_addendum = NULL; options->fingerprint_hash = -1; options->disable_forwarding = -1; + options->debian_banner = -1; } /* Returns 1 if a string option is unset or set to "none" or 0 otherwise. */ @@ -339,6 +340,8 @@ fill_default_server_options(ServerOptions *options) options->fingerprint_hash = SSH_FP_HASH_DEFAULT; if (options->disable_forwarding == -1) options->disable_forwarding = 0; + if (options->debian_banner == -1) + options->debian_banner = 1; assemble_algorithms(options); @@ -425,6 +428,7 @@ typedef enum { sAuthenticationMethods, sHostKeyAgent, sPermitUserRC, sStreamLocalBindMask, sStreamLocalBindUnlink, sAllowStreamLocalForwarding, sFingerprintHash, sDisableForwarding, + sDebianBanner, sDeprecated, sIgnore, sUnsupported } ServerOpCodes; @@ -577,6 +581,7 @@ static struct { { "allowstreamlocalforwarding", sAllowStreamLocalForwarding, SSHCFG_ALL }, { "fingerprinthash", sFingerprintHash, SSHCFG_GLOBAL }, { "disableforwarding", sDisableForwarding, SSHCFG_ALL }, + { "debianbanner", sDebianBanner, SSHCFG_GLOBAL }, { NULL, sBadOption, 0 } }; @@ -1866,6 +1871,10 @@ process_server_config_line(ServerOptions *options, char *line, options->fingerprint_hash = value; break; + case sDebianBanner: + intptr = &options->debian_banner; + goto parse_int; + case sDeprecated: case sIgnore: case sUnsupported: diff --git a/servconf.h b/servconf.h index 90dfa4c2..913a21b3 100644 --- a/servconf.h +++ b/servconf.h @@ -191,6 +191,8 @@ typedef struct { char *auth_methods[MAX_AUTH_METHODS]; int fingerprint_hash; + + int debian_banner; } ServerOptions; /* Information about the incoming connection as used by Match */ diff --git a/sshd.c b/sshd.c index 602f4740..f2f54b51 100644 --- a/sshd.c +++ b/sshd.c @@ -378,7 +378,8 @@ sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out) char remote_version[256]; /* Must be at least as big as buf. */ xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s\r\n", - PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_RELEASE, + PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, + options.debian_banner ? SSH_RELEASE : SSH_RELEASE_MINIMUM, *options.version_addendum == '\0' ? "" : " ", options.version_addendum); diff --git a/sshd_config.5 b/sshd_config.5 index 41ec6688..5f316481 100644 --- a/sshd_config.5 +++ b/sshd_config.5 @@ -530,6 +530,11 @@ or .Cm no . The default is .Cm yes . +.It Cm DebianBanner +Specifies whether the distribution-specified extra version suffix is +included during initial protocol handshake. +The default is +.Cm yes . .It Cm DenyGroups This keyword can be followed by a list of group name patterns, separated by spaces.