| From d13302656d9ff0807c5defe18623adc947f43a2b Mon Sep 17 00:00:00 2001 |
| From: Narpat Mali <narpat.mali@windriver.com> |
| Date: Wed, 8 Feb 2023 13:15:39 +0000 |
| Subject: [PATCH] agent: Disallow SET requests with any NULL varbind Merge pull |
| request #490 from fenner/set-null |
| |
| fixes: #474 and #475 |
| |
| CVE: CVE-2022-44792, CVE-2022-44793 |
| |
| Upstream-Status: Backport [https://github.com/net-snmp/net-snmp/commit/be804106fd0771a7d05236cff36e199af077af57] |
| |
| Signed-off-by: Narpat Mali <narpat.mali@windriver.com> |
| --- |
| agent/snmp_agent.c | 32 +++++++++++++++++++ |
| apps/snmpset.c | 1 + |
| .../default/T0142snmpv2csetnull_simple | 31 ++++++++++++++++++ |
| 3 files changed, 64 insertions(+) |
| create mode 100644 testing/fulltests/default/T0142snmpv2csetnull_simple |
| |
| diff --git a/agent/snmp_agent.c b/agent/snmp_agent.c |
| index 867d0c1..3f678fe 100644 |
| --- a/agent/snmp_agent.c |
| +++ b/agent/snmp_agent.c |
| @@ -3719,12 +3719,44 @@ netsnmp_handle_request(netsnmp_agent_session *asp, int status) |
| return 1; |
| } |
| |
| +static int |
| +check_set_pdu_for_null_varbind(netsnmp_agent_session *asp) |
| +{ |
| + int i; |
| + netsnmp_variable_list *v = NULL; |
| + |
| + for (i = 1, v = asp->pdu->variables; v != NULL; i++, v = v->next_variable) { |
| + if (v->type == ASN_NULL) { |
| + /* |
| + * Protect SET implementations that do not protect themselves |
| + * against wrong type. |
| + */ |
| + DEBUGMSGTL(("snmp_agent", "disallowing SET with NULL var for varbind %d\n", i)); |
| + asp->index = i; |
| + return SNMP_ERR_WRONGTYPE; |
| + } |
| + } |
| + return SNMP_ERR_NOERROR; |
| +} |
| + |
| int |
| handle_pdu(netsnmp_agent_session *asp) |
| { |
| int status, inclusives = 0; |
| netsnmp_variable_list *v = NULL; |
| |
| +#ifndef NETSNMP_NO_WRITE_SUPPORT |
| + /* |
| + * Check for ASN_NULL in SET request |
| + */ |
| + if (asp->pdu->command == SNMP_MSG_SET) { |
| + status = check_set_pdu_for_null_varbind(asp); |
| + if (status != SNMP_ERR_NOERROR) { |
| + return status; |
| + } |
| + } |
| +#endif /* NETSNMP_NO_WRITE_SUPPORT */ |
| + |
| /* |
| * for illegal requests, mark all nodes as ASN_NULL |
| */ |
| diff --git a/apps/snmpset.c b/apps/snmpset.c |
| index 48e14bd..d542713 100644 |
| --- a/apps/snmpset.c |
| +++ b/apps/snmpset.c |
| @@ -182,6 +182,7 @@ main(int argc, char *argv[]) |
| case 'x': |
| case 'd': |
| case 'b': |
| + case 'n': /* undocumented */ |
| #ifdef NETSNMP_WITH_OPAQUE_SPECIAL_TYPES |
| case 'I': |
| case 'U': |
| diff --git a/testing/fulltests/default/T0142snmpv2csetnull_simple b/testing/fulltests/default/T0142snmpv2csetnull_simple |
| new file mode 100644 |
| index 0000000..0f1b8f3 |
| --- /dev/null |
| +++ b/testing/fulltests/default/T0142snmpv2csetnull_simple |
| @@ -0,0 +1,31 @@ |
| +#!/bin/sh |
| + |
| +. ../support/simple_eval_tools.sh |
| + |
| +HEADER SNMPv2c set of system.sysContact.0 with NULL varbind |
| + |
| +SKIPIF NETSNMP_DISABLE_SET_SUPPORT |
| +SKIPIF NETSNMP_NO_WRITE_SUPPORT |
| +SKIPIF NETSNMP_DISABLE_SNMPV2C |
| +SKIPIFNOT USING_MIBII_SYSTEM_MIB_MODULE |
| + |
| +# |
| +# Begin test |
| +# |
| + |
| +# standard V2C configuration: testcomunnity |
| +snmp_write_access='all' |
| +. ./Sv2cconfig |
| +STARTAGENT |
| + |
| +CAPTURE "snmpget -On $SNMP_FLAGS -c testcommunity -v 2c $SNMP_TRANSPORT_SPEC:$SNMP_TEST_DEST$SNMP_SNMPD_PORT .1.3.6.1.2.1.1.4.0" |
| + |
| +CHECK ".1.3.6.1.2.1.1.4.0 = STRING:" |
| + |
| +CAPTURE "snmpset -On $SNMP_FLAGS -c testcommunity -v 2c $SNMP_TRANSPORT_SPEC:$SNMP_TEST_DEST$SNMP_SNMPD_PORT .1.3.6.1.2.1.1.4.0 n x" |
| + |
| +CHECK "Reason: wrongType" |
| + |
| +STOPAGENT |
| + |
| +FINISHED |
| -- |
| 2.34.1 |
| |