diff options
Diffstat (limited to 'net/sched/em_canid.c')
| -rw-r--r-- | net/sched/em_canid.c | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/net/sched/em_canid.c b/net/sched/em_canid.c new file mode 100644 index 000000000..ddd883ca5 --- /dev/null +++ b/net/sched/em_canid.c @@ -0,0 +1,233 @@ +/* + * em_canid.c Ematch rule to match CAN frames according to their CAN IDs + * + * This program is free software; you can distribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + * + * Idea: Oliver Hartkopp <oliver.hartkopp@volkswagen.de> + * Copyright: (c) 2011 Czech Technical University in Prague + * (c) 2011 Volkswagen Group Research + * Authors: Michal Sojka <sojkam1@fel.cvut.cz> + * Pavel Pisa <pisa@cmp.felk.cvut.cz> + * Rostislav Lisovy <lisovy@gmail.cz> + * Funded by: Volkswagen Group Research + */ + +#include <linux/slab.h> +#include <linux/module.h> +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/string.h> +#include <linux/skbuff.h> +#include <net/pkt_cls.h> +#include <linux/can.h> + +#define EM_CAN_RULES_MAX 500 + +struct canid_match { + /* For each SFF CAN ID (11 bit) there is one record in this bitfield */ + DECLARE_BITMAP(match_sff, (1 << CAN_SFF_ID_BITS)); + + int rules_count; + int sff_rules_count; + int eff_rules_count; + + /* + * Raw rules copied from netlink message; Used for sending + * information to userspace (when 'tc filter show' is invoked) + * AND when matching EFF frames + */ + struct can_filter rules_raw[]; +}; + +/** + * em_canid_get_id() - Extracts Can ID out of the sk_buff structure. + */ +static canid_t em_canid_get_id(struct sk_buff *skb) +{ + /* CAN ID is stored within the data field */ + struct can_frame *cf = (struct can_frame *)skb->data; + + return cf->can_id; +} + +static void em_canid_sff_match_add(struct canid_match *cm, u32 can_id, + u32 can_mask) +{ + int i; + + /* + * Limit can_mask and can_id to SFF range to + * protect against write after end of array + */ + can_mask &= CAN_SFF_MASK; + can_id &= can_mask; + + /* Single frame */ + if (can_mask == CAN_SFF_MASK) { + set_bit(can_id, cm->match_sff); + return; + } + + /* All frames */ + if (can_mask == 0) { + bitmap_fill(cm->match_sff, (1 << CAN_SFF_ID_BITS)); + return; + } + + /* + * Individual frame filter. + * Add record (set bit to 1) for each ID that + * conforms particular rule + */ + for (i = 0; i < (1 << CAN_SFF_ID_BITS); i++) { + if ((i & can_mask) == can_id) + set_bit(i, cm->match_sff); + } +} + +static inline struct canid_match *em_canid_priv(struct tcf_ematch *m) +{ + return (struct canid_match *)m->data; +} + +static int em_canid_match(struct sk_buff *skb, struct tcf_ematch *m, + struct tcf_pkt_info *info) +{ + struct canid_match *cm = em_canid_priv(m); + canid_t can_id; + int match = 0; + int i; + const struct can_filter *lp; + + can_id = em_canid_get_id(skb); + + if (can_id & CAN_EFF_FLAG) { + for (i = 0, lp = cm->rules_raw; + i < cm->eff_rules_count; i++, lp++) { + if (!(((lp->can_id ^ can_id) & lp->can_mask))) { + match = 1; + break; + } + } + } else { /* SFF */ + can_id &= CAN_SFF_MASK; + match = (test_bit(can_id, cm->match_sff) ? 1 : 0); + } + + return match; +} + +static int em_canid_change(struct net *net, void *data, int len, + struct tcf_ematch *m) +{ + struct can_filter *conf = data; /* Array with rules */ + struct canid_match *cm; + int i; + + if (!len) + return -EINVAL; + + if (len % sizeof(struct can_filter)) + return -EINVAL; + + if (len > sizeof(struct can_filter) * EM_CAN_RULES_MAX) + return -EINVAL; + + cm = kzalloc(sizeof(struct canid_match) + len, GFP_KERNEL); + if (!cm) + return -ENOMEM; + + cm->rules_count = len / sizeof(struct can_filter); + + /* + * We need two for() loops for copying rules into two contiguous + * areas in rules_raw to process all eff rules with a simple loop. + * NB: The configuration interface supports sff and eff rules. + * We do not support filters here that match for the same can_id + * provided in a SFF and EFF frame (e.g. 0x123 / 0x80000123). + * For this (unusual case) two filters have to be specified. The + * SFF/EFF separation is done with the CAN_EFF_FLAG in the can_id. + */ + + /* Fill rules_raw with EFF rules first */ + for (i = 0; i < cm->rules_count; i++) { + if (conf[i].can_id & CAN_EFF_FLAG) { + memcpy(cm->rules_raw + cm->eff_rules_count, + &conf[i], + sizeof(struct can_filter)); + + cm->eff_rules_count++; + } + } + + /* append SFF frame rules */ + for (i = 0; i < cm->rules_count; i++) { + if (!(conf[i].can_id & CAN_EFF_FLAG)) { + memcpy(cm->rules_raw + + cm->eff_rules_count + + cm->sff_rules_count, + &conf[i], sizeof(struct can_filter)); + + cm->sff_rules_count++; + + em_canid_sff_match_add(cm, + conf[i].can_id, conf[i].can_mask); + } + } + + m->datalen = sizeof(struct canid_match) + len; + m->data = (unsigned long)cm; + return 0; +} + +static void em_canid_destroy(struct tcf_ematch *m) +{ + struct canid_match *cm = em_canid_priv(m); + + kfree(cm); +} + +static int em_canid_dump(struct sk_buff *skb, struct tcf_ematch *m) +{ + struct canid_match *cm = em_canid_priv(m); + + /* + * When configuring this ematch 'rules_count' is set not to exceed + * 'rules_raw' array size + */ + if (nla_put_nohdr(skb, sizeof(struct can_filter) * cm->rules_count, + &cm->rules_raw) < 0) + return -EMSGSIZE; + + return 0; +} + +static struct tcf_ematch_ops em_canid_ops = { + .kind = TCF_EM_CANID, + .change = em_canid_change, + .match = em_canid_match, + .destroy = em_canid_destroy, + .dump = em_canid_dump, + .owner = THIS_MODULE, + .link = LIST_HEAD_INIT(em_canid_ops.link) +}; + +static int __init init_em_canid(void) +{ + return tcf_em_register(&em_canid_ops); +} + +static void __exit exit_em_canid(void) +{ + tcf_em_unregister(&em_canid_ops); +} + +MODULE_LICENSE("GPL"); + +module_init(init_em_canid); +module_exit(exit_em_canid); + +MODULE_ALIAS_TCF_EMATCH(TCF_EM_CANID); |