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BUG/MINOR: tcpcheck: Improve LDAP response parsing to fix LDAP check

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When the LDAP response is parsed, the message length is not properly
decoded. While it works for LDAP servers encoding it on 1 byte, it does not
work for those using a multi-bytes encoding. Among others, Active Directory
servers seems to encode messages or elements length on 4 bytes.

In this patch, we only handle length of BindResponse messages encoded on 1,
2 or 4 bytes. In theory, it may be encoded on any bytes number less than 127
bytes. But it is useless to make this part too complex. It should be ok this
way.

This patch should fix the issue #1390. It should be backported to all stable
versions. While it should be easy to backport it as far as 2.2, the patch
will have to be totally rewritten for lower versions.
This commit is contained in:
Christopher Faulet 2021-09-16 16:01:09 +02:00
parent c2afb860f2
commit 8a0e5f822b
2 changed files with 71 additions and 7 deletions
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19
reg-tests/checks/ldap-check.vtc
View File

@ -23,6 +23,13 @@ server s3 {
sendhex "300C020101 61 070A01 01 04000400"
} -start
server s4 {
recv 14
sendhex "308400000010020101 61 84000000070A01"
delay 0.1
sendhex "00 04000400"
} -start
syslog S1 -level notice {
recv
expect ~ "[^:\\[ ]\\[${h1_pid}\\]: Health check for server be1/srv succeeded, reason: Layer7 check passed.+info: \"Success\".+check duration: [[:digit:]]+ms, status: 1/1 UP."
@ -38,6 +45,11 @@ syslog S3 -level notice {
expect ~ "[^:\\[ ]\\[${h1_pid}\\]: Health check for server be3/srv failed, reason: Layer7 wrong status.+code: 1.+info: \"See RFC: http://tools.ietf.org/html/rfc4511#section-4.1.9\".+check duration: [[:digit:]]+ms, status: 0/1 DOWN."
} -start
syslog S4 -level notice {
recv
expect ~ "[^:\\[ ]\\[${h1_pid}\\]: Health check for server be4/srv succeeded, reason: Layer7 check passed.+info: \"Success\".+check duration: [[:digit:]]+ms, status: 1/1 UP."
} -start
haproxy h1 -conf {
defaults
mode tcp
@ -63,6 +75,12 @@ haproxy h1 -conf {
option ldap-check
server srv ${s3_addr}:${s3_port} check inter 1s rise 1 fall 1
backend be4
log ${S4_addr}:${S4_port} daemon
option log-health-checks
option ldap-check
server srv ${s4_addr}:${s4_port} check inter 1s rise 1 fall 1
listen ldap1
bind "fd@${ldap1}"
tcp-request inspect-delay 100ms
@ -75,3 +93,4 @@ haproxy h1 -conf {
syslog S1 -wait
syslog S2 -wait
syslog S3 -wait
syslog S4 -wait

59
src/tcpcheck.c
View File

@ -48,6 +48,7 @@
#include <haproxy/istbuf.h>
#include <haproxy/list.h>
#include <haproxy/log.h>
#include <haproxy/net_helper.h>
#include <haproxy/protocol.h>
#include <haproxy/proxy-t.h>
#include <haproxy/regex.h>
@ -656,7 +657,9 @@ enum tcpcheck_eval_ret tcpcheck_ldap_expect_bindrsp(struct check *check, struct
enum healthcheck_status status;
struct buffer *msg = NULL;
struct ist desc = IST_NULL;
unsigned short msglen = 0;
char *ptr;
unsigned short nbytes = 0;
size_t msglen = 0;
TRACE_ENTER(CHK_EV_TCPCHK_EXP, check);
@ -664,35 +667,65 @@ enum tcpcheck_eval_ret tcpcheck_ldap_expect_bindrsp(struct check *check, struct
* http://en.wikipedia.org/wiki/Basic_Encoding_Rules
* http://tools.ietf.org/html/rfc4511
*/
ptr = b_head(&check->bi) + 1;
/* size of LDAPMessage */
msglen = (*(b_head(&check->bi) + 1) & 0x80) ? (*(b_head(&check->bi) + 1) & 0x7f) : 0;
if (*ptr & 0x80) {
/* For message size encoded on several bytes, we only handle
* size encoded on 2 or 4 bytes. There is no reason to make this
* part to complex because only Active Directory is known to
* encode BindReponse length on 4 bytes.
*/
nbytes = (*ptr & 0x7f);
if (b_data(&check->bi) < 1 + nbytes)
goto too_short;
switch (nbytes) {
case 4: msglen = read_n32(ptr+1); break;
case 2: msglen = read_n16(ptr+1); break;
default:
status = HCHK_STATUS_L7RSP;
desc = ist("Not LDAPv3 protocol");
goto error;
}
}
else
msglen = *ptr;
ptr += 1 + nbytes;
if (b_data(&check->bi) < 2 + nbytes + msglen)
goto too_short;
/* http://tools.ietf.org/html/rfc4511#section-4.2.2
* messageID: 0x02 0x01 0x01: INTEGER 1
* protocolOp: 0x61: bindResponse
*/
if ((msglen > 2) || (memcmp(b_head(&check->bi) + 2 + msglen, "\x02\x01\x01\x61", 4) != 0)) {
if (memcmp(ptr, "\x02\x01\x01\x61", 4) != 0) {
status = HCHK_STATUS_L7RSP;
desc = ist("Not LDAPv3 protocol");
goto error;
}
ptr += 4;
/* size of bindResponse */
msglen += (*(b_head(&check->bi) + msglen + 6) & 0x80) ? (*(b_head(&check->bi) + msglen + 6) & 0x7f) : 0;
/* skip size of bindResponse */
nbytes = 0;
if (*ptr & 0x80)
nbytes = (*ptr & 0x7f);
ptr += 1 + nbytes;
/* http://tools.ietf.org/html/rfc4511#section-4.1.9
* ldapResult: 0x0a 0x01: ENUMERATION
*/
if ((msglen > 4) || (memcmp(b_head(&check->bi) + 7 + msglen, "\x0a\x01", 2) != 0)) {
if (memcmp(ptr, "\x0a\x01", 2) != 0) {
status = HCHK_STATUS_L7RSP;
desc = ist("Not LDAPv3 protocol");
goto error;
}
ptr += 2;
/* http://tools.ietf.org/html/rfc4511#section-4.1.9
* resultCode
*/
check->code = *(b_head(&check->bi) + msglen + 9);
check->code = *ptr;
if (check->code) {
status = HCHK_STATUS_L7STS;
desc = ist("See RFC: http://tools.ietf.org/html/rfc4511#section-4.1.9");
@ -714,6 +747,18 @@ enum tcpcheck_eval_ret tcpcheck_ldap_expect_bindrsp(struct check *check, struct
tcpcheck_expect_onerror_message(msg, check, rule, 0, desc);
set_server_check_status(check, status, (msg ? b_head(msg) : NULL));
goto out;
too_short:
if (!last_read)
goto wait_more_data;
/* invalid length or truncated response */
status = HCHK_STATUS_L7RSP;
goto error;
wait_more_data:
TRACE_DEVEL("waiting for more data", CHK_EV_TCPCHK_EXP, check);
ret = TCPCHK_EVAL_WAIT;
goto out;
}
/* Custom tcp-check expect function to parse and validate the SPOP hello agent