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Fix for NAS-Filter-Rule hack #2

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Fix for NAS-Filter-Rule hack #2

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94 changes: 43 additions & 51 deletions src/lib/radius.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1642,78 +1642,70 @@ int rad_vp2rfc(RADIUS_PACKET const *packet,
uint8_t const *end = ptr + room;
uint8_t *p, *attr = ptr;
bool zero = false;
uint8_t rule_buffer[1024] = {0};
size_t rule_len = 0;
VALUE_PAIR *current = vp;

attr[0] = PW_NAS_FILTER_RULE;
attr[1] = 2;
p = ptr + 2;

while (vp && !vp->da->vendor && (vp->da->attr == PW_NAS_FILTER_RULE)) {
if ((p + zero + vp->vp_length) > end) {
while (current && !current->da->vendor && (current->da->attr == PW_NAS_FILTER_RULE)) {
if ((rule_len + current->vp_length + 1) >= sizeof(rule_buffer)) {
break;
Comment on lines +1645 to 1651
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Copilot AI May 12, 2025

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Using a fixed-size rule_buffer may silently truncate data when the accumulated length exceeds its capacity; consider implementing explicit error logging or dynamic buffer resizing to handle such cases.

Copilot uses AI. Check for mistakes.
}

if (zero) {
if (attr[1] == 255) {
attr = p;
if ((attr + 3) >= end) break;

attr[0] = PW_NAS_FILTER_RULE;
attr[1] = 2;
p = attr + 2;
}

*(p++) = 0;
attr[1]++;
if (rule_len > 0) {
rule_buffer[rule_len++] = 0;
}
memcpy(rule_buffer + rule_len, current->vp_octets, current->vp_length);
rule_len += current->vp_length;

/*
* Check for overflow
*/
if ((attr[1] + vp->vp_length) < 255) {
memcpy(p, vp->vp_strvalue, vp->vp_length);
attr[1] += vp->vp_length;
p += vp->vp_length;

} else if (attr + (attr[1] + 2 + vp->vp_length) > end) {
break;
current = current->next;
}

} else if (vp->vp_length > 253) {
/*
* Drop VPs which are too long.
* We don't (yet) split one VP
* across multiple attributes.
*/
vp = vp->next;
continue;
attr[0] = PW_NAS_FILTER_RULE;
attr[1] = 2;
p = ptr + 2;

} else {
size_t first, second;
size_t offset = 0;
while (offset < rule_len) {
size_t rule_start = offset;
size_t next_rule = rule_start;
while (next_rule < rule_len && rule_buffer[next_rule] != 0) {
next_rule++;
}

first = 255 - attr[1];
second = vp->vp_length - first;
size_t this_rule_len = next_rule - rule_start;
if (this_rule_len == 0) {
offset = next_rule + 1;
continue;
}

memcpy(p, vp->vp_strvalue, first);
p += first;
attr[1] = 255;
size_t space_left = 255 - attr[1];
if (space_left < this_rule_len + (zero ? 1 : 0)) {
attr = p;
if ((attr + 2) >= end) {
break; }

attr[0] = PW_NAS_FILTER_RULE;
attr[1] = 2;
p = attr + 2;
zero = false;
}

memcpy(p, vp->vp_strvalue + first, second);
attr[1] += second;
p += second;
if (zero) {
*(p++) = 0;
attr[1]++;
}

vp = vp->next;
memcpy(p, rule_buffer + rule_start, this_rule_len);
p += this_rule_len;
attr[1] += this_rule_len;

offset = next_rule + 1;
zero = true;
}

*pvp = vp;
*pvp = current;
return p - ptr;
}

/*
* EAP-Message is special.
*/
Expand Down Expand Up @@ -3301,7 +3293,7 @@ static ssize_t data2vp_nas_filter_rule(TALLOC_CTX *ctx,
fr_strerror_printf("decode NAS-Filter-Rule: Out of memory");
return -1;
}

fr_pair_value_bstrncpy(vp, buffer, q - buffer);

*pvp = vp;
Expand Down Expand Up @@ -3708,7 +3700,7 @@ static ssize_t data2vp_wimax(TALLOC_CTX *ctx,
* + continuation, it's a bad attribute.
*/
if (attrlen < 8) {
raw:
raw:
/*
* It's not a Vendor-Specific, it's unknown...
*/
Expand Down
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