From 2f408deee4d88ebd2ee87bbf5fe227ff764e0e6d Mon Sep 17 00:00:00 2001 From: Calvin Morrison Date: Tue, 18 Aug 2026 22:05:20 -0400 Subject: rules: a rule set is not 64 kilobytes long fmtrules formatted into a 64K buffer with seprint, which clamps, and returned how much it had written. Nothing looked at whether that was everything. Since prepend, append and delete all work by formatting the whole set out, editing the text and parsing it back -- deliberately, so that a rule typed at ctl and a rule in a file go through one parser -- editing a set past the limit did not truncate the display, it truncated the rules. Measured with 2000 rules, about 104K formatted: and all of it comes back want: 2000 got: 1214 and survives an edit want: ok got: refused with nothing lost off the end got: 1214 786 rules gone from the running firewall, and the only sign is that the edit after it failed. save wrote the same short file, so reload would then have made the loss permanent. Now sized and allocated to fit. The bound is per rule -- the fixed attributes at their longest, plus the protocol, which is the only part whose length is ndb's choice rather than ours -- summed under the same lock that formats, so an install cannot get between the two passes. flows had the identical cap and gets the identical fix; on a busy firewall it is the file most likely to reach it. Rulebuf is gone. Six checks: a 2000-rule set loads, comes back whole, survives an edit, and saves whole. Co-Authored-By: Claude Opus 5 --- fw/src/rules.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 54 insertions(+), 13 deletions(-) (limited to 'fw/src/rules.c') diff --git a/fw/src/rules.c b/fw/src/rules.c index b5992b0..82a31a5 100644 --- a/fw/src/rules.c +++ b/fw/src/rules.c @@ -302,16 +302,47 @@ readrules(char *file) /* * The current set, written back out as ndb. What comes out here must * parse back in unchanged; it is what gets persisted. + * + * Allocated to fit, not written into 64K and clipped. A rule set that + * outgrew the buffer used to come back short, and since prepend, append + * and delete all work by formatting the set out, editing the text and + * parsing it again, editing one rule past the limit deleted every rule + * after it. Silently. */ -long -fmtrules(char *buf, long nbuf) +static long +rulesize(Rule *r) +{ + long n; + + /* + * "allow=out" and the fixed part of every attribute, an address + * and a mask at their longest, two ports, log=yes, the tabs and + * the newline. Only the protocol is unbounded, and it is ndb's + * word rather than anything we choose. + */ + n = 160; + if(r->proto != nil) + n += strlen(r->proto); + return n; +} + +char* +rulestext(void) { - char *p, *e; + char *buf, *p, *e; + long sz; Rule *r; - p = buf; - e = buf + nbuf; lock(&rulelock); + sz = 1; + for(r = rules; r != nil; r = r->next) + sz += rulesize(r); + if((buf = malloc(sz)) == nil){ + unlock(&rulelock); + return nil; + } + p = buf; + e = buf + sz; for(r = rules; r != nil; r = r->next){ p = seprint(p, e, "%s=%s", r->allow ? "allow" : "deny", r->verb == Vin ? "in" : r->verb == Vout ? "out" : "*"); @@ -328,7 +359,8 @@ fmtrules(char *buf, long nbuf) p = seprint(p, e, "\n"); } unlock(&rulelock); - return p - buf; + USED(p); + return buf; } /* @@ -375,18 +407,26 @@ dumprules(void) * The rules with a count of how often each has decided something. A * rule that has never fired is either dead or protecting you from * something that has not happened yet, and it is worth being able to - * tell which. Kept out of fmtrules so that what "rules" prints stays + * tell which. Kept out of rulestext so that what "rules" prints stays * a rule set that can be written straight back. */ -long -fmthits(char *buf, long nbuf) +char* +hitstext(void) { - char *p, *e; + char *buf, *p, *e; + long sz; Rule *r; - p = buf; - e = buf + nbuf; lock(&rulelock); + sz = 1; + for(r = rules; r != nil; r = r->next) + sz += 64 + (r->proto != nil ? strlen(r->proto) : 0); + if((buf = malloc(sz)) == nil){ + unlock(&rulelock); + return nil; + } + p = buf; + e = buf + sz; for(r = rules; r != nil; r = r->next) p = seprint(p, e, "%-8ld %s=%s%s%s\n", r->hits, r->allow ? "allow" : "deny", @@ -394,7 +434,8 @@ fmthits(char *buf, long nbuf) r->proto != nil ? "\tproto=" : "", r->proto != nil ? r->proto : ""); unlock(&rulelock); - return p - buf; + USED(p); + return buf; } int -- cgit v1.2.3