BTW, the subjects for the tracing subsystem should always start with a capital letter.
"tracing: Support IPv6 filter predicates"
But that's not why I'm replying here.
On Fri, 28 Apr 2023 16:34:46 +0100 Alan Maguire alan.maguire@oracle.com wrote:
Support '==' and '!=' predicates for IPv6 addresses; for example
cd /sys/kernel/debug/tracing/events/tcp/tcp_receive_reset echo "saddr_v6 == ::1" > filter
or equivalently
echo "saddr_v6 == 0:0:0:0:0:0:0:1" > filter
Signed-off-by: Alan Maguire alan.maguire@oracle.com
kernel/trace/trace_events_filter.c | 73 ++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+)
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index d8e08d3c3594..e2521574f3c4 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -1665,6 +1665,79 @@ static int parse_pred(const char *str, void *data, if (pred->op == OP_NE) pred->not = 1;
- } else if (field->size == 16 &&
(str[i] == ':' ||(isalnum(str[i]) && tolower(str[i + 1]) != 'x'))) {u8 j, gap_size, gap = 0, gap_count = 0, index = 0;u16 tmp_v6addr[8] = {};u16 v6addr[8] = {};/* For IPv6 addresses, only '==' or '!=' are supported. */if (pred->op != OP_EQ && pred->op != OP_NE) {parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, pos + i);goto err_free;}/* Store the u16s in the address string consecutively in* tmp_v6addr while tracking the presence of a "::" (if any)* in the IPv6 address string; we will use its location* to determine how many u16s it represents (the gap_size* below). Only one "::" is allowed in an IPv6 address* string.*/while (isalnum(str[i]) || str[i] == ':') {switch (str[i]) {case ':':i++;/* mark "::" index by setting gap */if (str[i] == ':') {gap = index;gap_count++;i++;}if (gap_count > 1) {parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP,pos + s);goto err_free;}break;default:if (sscanf(&str[i], "%hx", &tmp_v6addr[index]) != 1) {parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP,pos + s);goto err_free;}index++;while (isalnum(str[i]))i++;break;}}
There appears to be no limit to the above loop. I panic'd my machine with:
# echo 'saddr_v6 == 0123:4567:89ab:cdef:0123:4567:89ab:cdef:0123:4567:89ab:cdef:0123:4567:89ab:cdef:0123:4567:89ab:cdef:0123:4567:89ab:cdef:0123:4567:89ab:cdef:0123:4567:89ab:cdef' > /sys/kernel/tracing/events/sock/inet_sk_error_report/filter
-- Steve
/* The gap_size here represents the number of u16s the "::"* represents; for ::1 the gap size is 7, for feed::face* it is 6, etc.*/gap_size = 8 - index;index = 0;for (j = 0; j < 8; ) {if (gap_size > 0 && j == gap) {j += gap_size;} else {+#ifdef __BIG_ENDIAN
v6addr[j++] = tmp_v6addr[index];+#else
v6addr[j++] = ((tmp_v6addr[index] & 0xff) << 8) +((tmp_v6addr[index] & 0xff00) >> 8);+#endif
index++;}}pred_val = kzalloc(field->size, GFP_KERNEL);memcpy(pred_val, v6addr, field->size);pred->val = (u64)pred_val;pred->fn_num = FILTER_PRED_FN_MEMCMP;if (pred->op == OP_NE)pred->not = 1;- } else if (str[i] == '0' && tolower(str[i + 1]) == 'x' && field->size > 8) { /* For sizes > 8 bytes, we store hex bytes for comparison;