dccp: Registration routines for changing feature values
Two registration routines, for SP and NN features, are provided by this patch,
replacing a previous routine which was used for both feature types.
These are internal-only routines and therefore start with `__feat_register'.
It further exports the known limits of Sequence Window and Ack Ratio as symbolic
constants.
Signed-off-by: Gerrit Renker <gerrit@xxxxxxxxxxxxxx>
Acked-by: Ian McDonald <ian.mcdonald@xxxxxxxxxxx>
---
net/dccp/ccids/ccid2.c | 6 -
net/dccp/feat.c | 192 +++++++++++++++++++++++++++++++++++++++++++------
net/dccp/feat.h | 25 ++++++
net/dccp/proto.c | 2
4 files changed, 197 insertions(+), 28 deletions(-)
--- a/net/dccp/feat.h
+++ b/net/dccp/feat.h
@@ -14,6 +14,15 @@
#include <linux/types.h>
#include "dccp.h"
+/*
+ * Known limit values
+ */
+/* Ack Ratio takes 2-byte integer values (11.3) */
+#define DCCPF_ACK_RATIO_MAX 0xFFFF
+/* Wmin=32 and Wmax=2^46-1 from 7.5.2 */
+#define DCCPF_SEQ_WMIN 32
+#define DCCPF_SEQ_WMAX 0x3FFFFFFFFFFFull
+
enum dccp_feat_type {
FEAT_AT_RX = 1, /* located at RX side of half-connection */
FEAT_AT_TX = 2, /* located at TX side of half-connection */
@@ -75,6 +84,20 @@ static inline u8 dccp_feat_genopt(struct
return entry->is_local ? DCCPO_CHANGE_L : DCCPO_CHANGE_R;
}
+/**
+ * struct ccid_dependency - Track changes resulting from choosing a CCID
+ * @dependent_feat: one of %dccp_feature_numbers
+ * @is_local: local (1) or remote (0) @dependent_feat
+ * @is_mandatory: whether presence of @dependent_feat is mission-critical or not
+ * @val: corresponding default value for @dependent_feat (u8 is sufficient here)
+ */
+struct ccid_dependency {
+ u8 dependent_feat;
+ bool is_local:1,
+ is_mandatory:1;
+ u8 val;
+};
+
#ifdef CONFIG_IP_DCCP_DEBUG
extern const char *dccp_feat_typename(const u8 type);
extern const char *dccp_feat_name(const u8 feat);
@@ -97,6 +120,6 @@ extern int dccp_feat_confirm_recv(struc
extern void dccp_feat_clean(struct dccp_minisock *dmsk);
extern int dccp_feat_clone(struct sock *oldsk, struct sock *newsk);
extern int dccp_feat_clone_list(struct list_head const *, struct list_head *);
-extern int dccp_feat_init(struct dccp_minisock *dmsk);
+extern int dccp_feat_init(struct sock *sk);
#endif /* _DCCP_FEAT_H */
--- a/net/dccp/feat.c
+++ b/net/dccp/feat.c
@@ -92,6 +92,18 @@ static u8 dccp_feat_type(u8 feat_num)
return dccp_feat_table[idx].reconciliation;
}
+static int dccp_feat_default_value(u8 feat_num)
+{
+ int idx = dccp_feat_index(feat_num);
+ /*
+ * There are no default values for unknown features, so encountering a
+ * negative index here indicates a serious problem somewhere else.
+ */
+ DCCP_BUG_ON(idx < 0);
+
+ return idx < 0 ? 0 : dccp_feat_table[idx].default_value;
+}
+
/* copy constructor, fval must not already contain allocated memory */
static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
{
@@ -155,6 +167,63 @@ static void dccp_feat_entry_destructor(s
* - list is sorted in increasing order of feature number (faster lookup)
*/
+/**
+ * dccp_feat_entry_new - Central list update routine (called by all others)
+ * @head: list to add to
+ * @feat: feature number
+ * @local: whether the local (1) or remote feature with number @feat is meant
+ * This is the only constructor and serves to ensure the above invariants.
+ */
+static struct dccp_feat_entry *
+ dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
+{
+ struct dccp_feat_entry *entry;
+
+ list_for_each_entry(entry, head, node)
+ if (entry->feat_num == feat && entry->is_local == local) {
+ dccp_feat_val_destructor(entry->feat_num, &entry->val);
+ return entry;
+ } else if (entry->feat_num > feat) {
+ head = &entry->node;
+ break;
+ }
+
+ entry = kmalloc(sizeof(*entry), gfp_any());
+ if (entry != NULL) {
+ entry->feat_num = feat;
+ entry->is_local = local;
+ list_add_tail(&entry->node, head);
+ }
+ return entry;
+}
+
+/**
+ * dccp_feat_push_change - Add/overwrite a Change option in the list
+ * @fn_list: feature-negotiation list to update
+ * @feat: one of %dccp_feature_numbers
+ * @local: whether local (1) or remote (0) @feat_num is meant
+ * @needs_mandatory: whether to use Mandatory feature negotiation options
+ * @fval: pointer to NN/SP value to be inserted (will be copied)
+ */
+static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
+ u8 mandatory, dccp_feat_val *fval)
+{
+ struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
+
+ if (new == NULL)
+ return -ENOMEM;
+
+ new->feat_num = feat;
+ new->is_local = local;
+ new->state = FEAT_INITIALISING;
+ new->needs_confirm = 0;
+ new->empty_confirm = 0;
+ new->val = *fval;
+ new->needs_mandatory = mandatory;
+
+ return 0;
+}
+
static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
{
list_del(&entry->node);
@@ -190,6 +259,95 @@ cloning_failed:
return -ENOMEM;
}
+static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
+{
+ switch (feat_num) {
+ case DCCPF_ACK_RATIO:
+ return val <= DCCPF_ACK_RATIO_MAX;
+ case DCCPF_SEQUENCE_WINDOW:
+ return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
+ }
+ return 0; /* feature unknown - so we can't tell */
+}
+
+/* check that SP values are within the ranges defined in RFC 4340 */
+static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
+{
+ switch (feat_num) {
+ case DCCPF_CCID:
+ return val == DCCPC_CCID2 || val == DCCPC_CCID3;
+ /* Type-check Boolean feature values: */
+ case DCCPF_SHORT_SEQNOS:
+ case DCCPF_ECN_INCAPABLE:
+ case DCCPF_SEND_ACK_VECTOR:
+ case DCCPF_SEND_NDP_COUNT:
+ case DCCPF_DATA_CHECKSUM:
+ case DCCPF_SEND_LEV_RATE:
+ return val < 2;
+ case DCCPF_MIN_CSUM_COVER:
+ return val < 16;
+ }
+ return 0; /* feature unknown */
+}
+
+static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
+{
+ if (sp_list == NULL || sp_len < 1)
+ return 0;
+ while (sp_len--)
+ if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
+ return 0;
+ return 1;
+}
+
+/**
+ * __feat_register_nn - Register new NN value on socket
+ * @fn: feature-negotiation list to register with
+ * @feat: an NN feature from %dccp_feature_numbers
+ * @mandatory: use Mandatory option if 1
+ * @nn_val: value to register (restricted to 4 bytes)
+ * Note that NN features are local by definition (RFC 4340, 6.3.2).
+ */
+static int __feat_register_nn(struct list_head *fn, u8 feat,
+ u8 mandatory, u64 nn_val)
+{
+ dccp_feat_val fval = { .nn = nn_val };
+
+ if (dccp_feat_type(feat) != FEAT_NN ||
+ !dccp_feat_is_valid_nn_val(feat, nn_val))
+ return -EINVAL;
+
+ /* Don't bother with default values, they will be activated anyway. */
+ if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
+ return 0;
+
+ return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
+}
+
+/**
+ * __feat_register_sp - Register new SP value/list on socket
+ * @fn: feature-negotiation list to register with
+ * @feat: an SP feature from %dccp_feature_numbers
+ * @is_local: whether the local (1) or the remote (0) @feat is meant
+ * @mandatory: use Mandatory option if 1
+ * @sp_val: SP value followed by optional preference list
+ * @sp_len: length of @sp_val in bytes
+ */
+static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
+ u8 mandatory, u8 const *sp_val, u8 sp_len)
+{
+ dccp_feat_val fval;
+
+ if (dccp_feat_type(feat) != FEAT_SP ||
+ !dccp_feat_sp_list_ok(feat, sp_val, sp_len))
+ return -EINVAL;
+
+ if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
+ return -ENOMEM;
+
+ return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval);
+}
+
int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
u8 *val, u8 len, gfp_t gfp)
{
@@ -726,42 +884,30 @@ out_clean:
EXPORT_SYMBOL_GPL(dccp_feat_clone);
-static int __dccp_feat_init(struct dccp_minisock *dmsk, u8 type, u8 feat,
- u8 *val, u8 len)
-{
- int rc = -ENOMEM;
- u8 *copy = kmemdup(val, len, GFP_KERNEL);
-
- if (copy != NULL) {
- rc = dccp_feat_change(dmsk, type, feat, copy, len, GFP_KERNEL);
- if (rc)
- kfree(copy);
- }
- return rc;
-}
-
-int dccp_feat_init(struct dccp_minisock *dmsk)
+int dccp_feat_init(struct sock *sk)
{
+ struct dccp_sock *dp = dccp_sk(sk);
+ struct dccp_minisock *dmsk = dccp_msk(sk);
int rc;
- INIT_LIST_HEAD(&dmsk->dccpms_pending);
- INIT_LIST_HEAD(&dmsk->dccpms_conf);
+ INIT_LIST_HEAD(&dmsk->dccpms_pending); /* XXX no longer used */
+ INIT_LIST_HEAD(&dmsk->dccpms_conf); /* XXX no longer used */
/* CCID L */
- rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_CCID,
- &dmsk->dccpms_tx_ccid, 1);
+ rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 1, 0,
+ &dmsk->dccpms_tx_ccid, 1);
if (rc)
goto out;
/* CCID R */
- rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_R, DCCPF_CCID,
- &dmsk->dccpms_rx_ccid, 1);
+ rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 0, 0,
+ &dmsk->dccpms_rx_ccid, 1);
if (rc)
goto out;
/* Ack ratio */
- rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_ACK_RATIO,
- &dmsk->dccpms_ack_ratio, 1);
+ rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0,
+ dmsk->dccpms_ack_ratio);
out:
return rc;
}
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -202,7 +202,7 @@ int dccp_init_sock(struct sock *sk, cons
* setsockopt(CCIDs-I-want/accept). -acme
*/
if (likely(ctl_sock_initialized)) {
- int rc = dccp_feat_init(dmsk);
+ int rc = dccp_feat_init(sk);
if (rc)
return rc;
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -25,7 +25,7 @@
/*
* This implementation should follow RFC 4341
*/
-
+#include "../feat.h"
#include "../ccid.h"
#include "../dccp.h"
#include "ccid2.h"
@@ -147,8 +147,8 @@ static void ccid2_change_l_ack_ratio(str
DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
val = max_ratio;
}
- if (val > 0xFFFF) /* RFC 4340, 11.3 */
- val = 0xFFFF;
+ if (val > DCCPF_ACK_RATIO_MAX)
+ val = DCCPF_ACK_RATIO_MAX;
if (val == dp->dccps_l_ack_ratio)
return;
--
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