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Merge pull request #15628 from opensourcerouting/fix/bgp_prefix_sid_crash

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bgpd: Fix error handling when receiving BGP Prefix SID attribute
This commit is contained in:
Russ White 2024-04-02 11:17:52 -04:00 committed by GitHub
commit 6bea75f18c
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GPG Key ID: B5690EEEBB952194
1 changed files with 25 additions and 13 deletions
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38
bgpd/bgp_attr.c
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@ -1389,6 +1389,15 @@ bgp_attr_malformed(struct bgp_attr_parser_args *args, uint8_t subcode,
(args->startp - STREAM_DATA(BGP_INPUT(peer)))
+ args->total);
/* Partial optional attributes that are malformed should not cause
* the whole session to be reset. Instead treat it as a withdrawal
* of the routes, if possible.
*/
if (CHECK_FLAG(flags, BGP_ATTR_FLAG_TRANS) &&
CHECK_FLAG(flags, BGP_ATTR_FLAG_OPTIONAL) &&
CHECK_FLAG(flags, BGP_ATTR_FLAG_PARTIAL))
return BGP_ATTR_PARSE_WITHDRAW;
switch (args->type) {
/* where an attribute is relatively inconsequential, e.g. it does not
* affect route selection, and can be safely ignored, then any such
@ -1398,6 +1407,7 @@ bgp_attr_malformed(struct bgp_attr_parser_args *args, uint8_t subcode,
case BGP_ATTR_AS4_AGGREGATOR:
case BGP_ATTR_AGGREGATOR:
case BGP_ATTR_ATOMIC_AGGREGATE:
case BGP_ATTR_PREFIX_SID:
return BGP_ATTR_PARSE_PROCEED;
/* Core attributes, particularly ones which may influence route
@ -1425,19 +1435,21 @@ bgp_attr_malformed(struct bgp_attr_parser_args *args, uint8_t subcode,
BGP_NOTIFY_UPDATE_ERR, subcode,
notify_datap, length);
return BGP_ATTR_PARSE_ERROR;
default:
/* Unknown attributes, that are handled by this function
* should be treated as withdraw, to prevent one more CVE
* from being introduced.
* RFC 7606 says:
* The "treat-as-withdraw" approach is generally preferred
* and the "session reset" approach is discouraged.
*/
flog_err(EC_BGP_ATTR_FLAG,
"%s(%u) attribute received, while it is not known how to handle it, treating as withdraw",
lookup_msg(attr_str, args->type, NULL), args->type);
break;
}
/* Partial optional attributes that are malformed should not cause
* the whole session to be reset. Instead treat it as a withdrawal
* of the routes, if possible.
*/
if (CHECK_FLAG(flags, BGP_ATTR_FLAG_TRANS)
&& CHECK_FLAG(flags, BGP_ATTR_FLAG_OPTIONAL)
&& CHECK_FLAG(flags, BGP_ATTR_FLAG_PARTIAL))
return BGP_ATTR_PARSE_WITHDRAW;
/* default to reset */
return BGP_ATTR_PARSE_ERROR_NOTIFYPLS;
return BGP_ATTR_PARSE_WITHDRAW;
}
/* Find out what is wrong with the path attribute flag bits and log the error.
@ -3163,8 +3175,6 @@ enum bgp_attr_parse_ret bgp_attr_prefix_sid(struct bgp_attr_parser_args *args)
struct attr *const attr = args->attr;
enum bgp_attr_parse_ret ret;
attr->flag |= ATTR_FLAG_BIT(BGP_ATTR_PREFIX_SID);
uint8_t type;
uint16_t length;
size_t headersz = sizeof(type) + sizeof(length);
@ -3214,6 +3224,8 @@ enum bgp_attr_parse_ret bgp_attr_prefix_sid(struct bgp_attr_parser_args *args)
}
}
SET_FLAG(attr->flag, ATTR_FLAG_BIT(BGP_ATTR_PREFIX_SID));
return BGP_ATTR_PARSE_PROCEED;
}