/* * 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 tcf_proto *tp, void *data, int len, struct tcf_ematch *m) { struct can_filter *conf = data; /* Array with rules */ struct canid_match *cm; struct canid_match *cm_old = (struct canid_match *)m->data; 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; if (cm_old != NULL) { pr_err("canid: Configuring an existing ematch!\n"); kfree(cm_old); } return 0; } static void em_canid_destroy(struct tcf_proto *tp, 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);