| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * em_canid.c Ematch rule to match CAN frames according to their CAN IDs |
| * |
| * 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. |
| * @skb: buffer to extract Can ID from |
| */ |
| 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_DESCRIPTION("ematch classifier to match CAN IDs embedded in skb CAN frames"); |
| MODULE_LICENSE("GPL"); |
| |
| module_init(init_em_canid); |
| module_exit(exit_em_canid); |
| |
| MODULE_ALIAS_TCF_EMATCH(TCF_EM_CANID); |