net/caif/cfpkt_skbuff.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (C) ST-Ericsson AB 2010
0004  * Author:  Sjur Brendeland
0005  */
0006
0007 #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
0008
0009 #include <linux/string.h>
0010 #include <linux/skbuff.h>
0011 #include <linux/export.h>
0012 #include <net/caif/cfpkt.h>
0013
0014 #define PKT_PREFIX  48
0015 #define PKT_POSTFIX 2
0016 #define PKT_LEN_WHEN_EXTENDING 128
0017 #define PKT_ERROR(pkt, errmsg)         \
0018 do {                       \
0019     cfpkt_priv(pkt)->erronous = true;  \
0020     skb_reset_tail_pointer(&pkt->skb); \
0021     pr_warn(errmsg);           \
0022 } while (0)
0023
0024 struct cfpktq {
0025     struct sk_buff_head head;
0026     atomic_t count;
0027     /* Lock protects count updates */
0028     spinlock_t lock;
0029 };
0030
0031 /*
0032  * net/caif/ is generic and does not
0033  * understand SKB, so we do this typecast
0034  */
0035 struct cfpkt {
0036     struct sk_buff skb;
0037 };
0038
0039 /* Private data inside SKB */
0040 struct cfpkt_priv_data {
0041     struct dev_info dev_info;
0042     bool erronous;
0043 };
0044
0045 static inline struct cfpkt_priv_data *cfpkt_priv(struct cfpkt *pkt)
0046 {
0047     return (struct cfpkt_priv_data *) pkt->skb.cb;
0048 }
0049
0050 static inline bool is_erronous(struct cfpkt *pkt)
0051 {
0052     return cfpkt_priv(pkt)->erronous;
0053 }
0054
0055 static inline struct sk_buff *pkt_to_skb(struct cfpkt *pkt)
0056 {
0057     return &pkt->skb;
0058 }
0059
0060 static inline struct cfpkt *skb_to_pkt(struct sk_buff *skb)
0061 {
0062     return (struct cfpkt *) skb;
0063 }
0064
0065 struct cfpkt *cfpkt_fromnative(enum caif_direction dir, void *nativepkt)
0066 {
0067     struct cfpkt *pkt = skb_to_pkt(nativepkt);
0068     cfpkt_priv(pkt)->erronous = false;
0069     return pkt;
0070 }
0071 EXPORT_SYMBOL(cfpkt_fromnative);
0072
0073 void *cfpkt_tonative(struct cfpkt *pkt)
0074 {
0075     return (void *) pkt;
0076 }
0077 EXPORT_SYMBOL(cfpkt_tonative);
0078
0079 static struct cfpkt *cfpkt_create_pfx(u16 len, u16 pfx)
0080 {
0081     struct sk_buff *skb;
0082
0083     skb = alloc_skb(len + pfx, GFP_ATOMIC);
0084     if (unlikely(skb == NULL))
0085         return NULL;
0086
0087     skb_reserve(skb, pfx);
0088     return skb_to_pkt(skb);
0089 }
0090
0091 inline struct cfpkt *cfpkt_create(u16 len)
0092 {
0093     return cfpkt_create_pfx(len + PKT_POSTFIX, PKT_PREFIX);
0094 }
0095
0096 void cfpkt_destroy(struct cfpkt *pkt)
0097 {
0098     struct sk_buff *skb = pkt_to_skb(pkt);
0099     kfree_skb(skb);
0100 }
0101
0102 inline bool cfpkt_more(struct cfpkt *pkt)
0103 {
0104     struct sk_buff *skb = pkt_to_skb(pkt);
0105     return skb->len > 0;
0106 }
0107
0108 int cfpkt_peek_head(struct cfpkt *pkt, void *data, u16 len)
0109 {
0110     struct sk_buff *skb = pkt_to_skb(pkt);
0111     if (skb_headlen(skb) >= len) {
0112         memcpy(data, skb->data, len);
0113         return 0;
0114     }
0115     return !cfpkt_extr_head(pkt, data, len) &&
0116         !cfpkt_add_head(pkt, data, len);
0117 }
0118
0119 int cfpkt_extr_head(struct cfpkt *pkt, void *data, u16 len)
0120 {
0121     struct sk_buff *skb = pkt_to_skb(pkt);
0122     u8 *from;
0123     if (unlikely(is_erronous(pkt)))
0124         return -EPROTO;
0125
0126     if (unlikely(len > skb->len)) {
0127         PKT_ERROR(pkt, "read beyond end of packet\n");
0128         return -EPROTO;
0129     }
0130
0131     if (unlikely(len > skb_headlen(skb))) {
0132         if (unlikely(skb_linearize(skb) != 0)) {
0133             PKT_ERROR(pkt, "linearize failed\n");
0134             return -EPROTO;
0135         }
0136     }
0137     from = skb_pull(skb, len);
0138     from -= len;
0139     if (data)
0140         memcpy(data, from, len);
0141     return 0;
0142 }
0143 EXPORT_SYMBOL(cfpkt_extr_head);
0144
0145 int cfpkt_extr_trail(struct cfpkt *pkt, void *dta, u16 len)
0146 {
0147     struct sk_buff *skb = pkt_to_skb(pkt);
0148     u8 *data = dta;
0149     u8 *from;
0150     if (unlikely(is_erronous(pkt)))
0151         return -EPROTO;
0152
0153     if (unlikely(skb_linearize(skb) != 0)) {
0154         PKT_ERROR(pkt, "linearize failed\n");
0155         return -EPROTO;
0156     }
0157     if (unlikely(skb->data + len > skb_tail_pointer(skb))) {
0158         PKT_ERROR(pkt, "read beyond end of packet\n");
0159         return -EPROTO;
0160     }
0161     from = skb_tail_pointer(skb) - len;
0162     skb_trim(skb, skb->len - len);
0163     memcpy(data, from, len);
0164     return 0;
0165 }
0166
0167 int cfpkt_pad_trail(struct cfpkt *pkt, u16 len)
0168 {
0169     return cfpkt_add_body(pkt, NULL, len);
0170 }
0171
0172 int cfpkt_add_body(struct cfpkt *pkt, const void *data, u16 len)
0173 {
0174     struct sk_buff *skb = pkt_to_skb(pkt);
0175     struct sk_buff *lastskb;
0176     u8 *to;
0177     u16 addlen = 0;
0178
0179
0180     if (unlikely(is_erronous(pkt)))
0181         return -EPROTO;
0182
0183     lastskb = skb;
0184
0185     /* Check whether we need to add space at the tail */
0186     if (unlikely(skb_tailroom(skb) < len)) {
0187         if (likely(len < PKT_LEN_WHEN_EXTENDING))
0188             addlen = PKT_LEN_WHEN_EXTENDING;
0189         else
0190             addlen = len;
0191     }
0192
0193     /* Check whether we need to change the SKB before writing to the tail */
0194     if (unlikely((addlen > 0) || skb_cloned(skb) || skb_shared(skb))) {
0195
0196         /* Make sure data is writable */
0197         if (unlikely(skb_cow_data(skb, addlen, &lastskb) < 0)) {
0198             PKT_ERROR(pkt, "cow failed\n");
0199             return -EPROTO;
0200         }
0201     }
0202
0203     /* All set to put the last SKB and optionally write data there. */
0204     to = pskb_put(skb, lastskb, len);
0205     if (likely(data))
0206         memcpy(to, data, len);
0207     return 0;
0208 }
0209
0210 inline int cfpkt_addbdy(struct cfpkt *pkt, u8 data)
0211 {
0212     return cfpkt_add_body(pkt, &data, 1);
0213 }
0214
0215 int cfpkt_add_head(struct cfpkt *pkt, const void *data2, u16 len)
0216 {
0217     struct sk_buff *skb = pkt_to_skb(pkt);
0218     struct sk_buff *lastskb;
0219     u8 *to;
0220     const u8 *data = data2;
0221     int ret;
0222     if (unlikely(is_erronous(pkt)))
0223         return -EPROTO;
0224     if (unlikely(skb_headroom(skb) < len)) {
0225         PKT_ERROR(pkt, "no headroom\n");
0226         return -EPROTO;
0227     }
0228
0229     /* Make sure data is writable */
0230     ret = skb_cow_data(skb, 0, &lastskb);
0231     if (unlikely(ret < 0)) {
0232         PKT_ERROR(pkt, "cow failed\n");
0233         return ret;
0234     }
0235
0236     to = skb_push(skb, len);
0237     memcpy(to, data, len);
0238     return 0;
0239 }
0240 EXPORT_SYMBOL(cfpkt_add_head);
0241
0242 inline int cfpkt_add_trail(struct cfpkt *pkt, const void *data, u16 len)
0243 {
0244     return cfpkt_add_body(pkt, data, len);
0245 }
0246
0247 inline u16 cfpkt_getlen(struct cfpkt *pkt)
0248 {
0249     struct sk_buff *skb = pkt_to_skb(pkt);
0250     return skb->len;
0251 }
0252
0253 int cfpkt_iterate(struct cfpkt *pkt,
0254           u16 (*iter_func)(u16, void *, u16),
0255           u16 data)
0256 {
0257     /*
0258      * Don't care about the performance hit of linearizing,
0259      * Checksum should not be used on high-speed interfaces anyway.
0260      */
0261     if (unlikely(is_erronous(pkt)))
0262         return -EPROTO;
0263     if (unlikely(skb_linearize(&pkt->skb) != 0)) {
0264         PKT_ERROR(pkt, "linearize failed\n");
0265         return -EPROTO;
0266     }
0267     return iter_func(data, pkt->skb.data, cfpkt_getlen(pkt));
0268 }
0269
0270 int cfpkt_setlen(struct cfpkt *pkt, u16 len)
0271 {
0272     struct sk_buff *skb = pkt_to_skb(pkt);
0273
0274
0275     if (unlikely(is_erronous(pkt)))
0276         return -EPROTO;
0277
0278     if (likely(len <= skb->len)) {
0279         if (unlikely(skb->data_len))
0280             ___pskb_trim(skb, len);
0281         else
0282             skb_trim(skb, len);
0283
0284         return cfpkt_getlen(pkt);
0285     }
0286
0287     /* Need to expand SKB */
0288     if (unlikely(!cfpkt_pad_trail(pkt, len - skb->len)))
0289         PKT_ERROR(pkt, "skb_pad_trail failed\n");
0290
0291     return cfpkt_getlen(pkt);
0292 }
0293
0294 struct cfpkt *cfpkt_append(struct cfpkt *dstpkt,
0295                struct cfpkt *addpkt,
0296                u16 expectlen)
0297 {
0298     struct sk_buff *dst = pkt_to_skb(dstpkt);
0299     struct sk_buff *add = pkt_to_skb(addpkt);
0300     u16 addlen = skb_headlen(add);
0301     u16 neededtailspace;
0302     struct sk_buff *tmp;
0303     u16 dstlen;
0304     u16 createlen;
0305     if (unlikely(is_erronous(dstpkt) || is_erronous(addpkt))) {
0306         return dstpkt;
0307     }
0308     if (expectlen > addlen)
0309         neededtailspace = expectlen;
0310     else
0311         neededtailspace = addlen;
0312
0313     if (dst->tail + neededtailspace > dst->end) {
0314         /* Create a dumplicate of 'dst' with more tail space */
0315         struct cfpkt *tmppkt;
0316         dstlen = skb_headlen(dst);
0317         createlen = dstlen + neededtailspace;
0318         tmppkt = cfpkt_create(createlen + PKT_PREFIX + PKT_POSTFIX);
0319         if (tmppkt == NULL)
0320             return NULL;
0321         tmp = pkt_to_skb(tmppkt);
0322         skb_put_data(tmp, dst->data, dstlen);
0323         cfpkt_destroy(dstpkt);
0324         dst = tmp;
0325     }
0326     skb_put_data(dst, add->data, skb_headlen(add));
0327     cfpkt_destroy(addpkt);
0328     return skb_to_pkt(dst);
0329 }
0330
0331 struct cfpkt *cfpkt_split(struct cfpkt *pkt, u16 pos)
0332 {
0333     struct sk_buff *skb2;
0334     struct sk_buff *skb = pkt_to_skb(pkt);
0335     struct cfpkt *tmppkt;
0336     u8 *split = skb->data + pos;
0337     u16 len2nd = skb_tail_pointer(skb) - split;
0338
0339     if (unlikely(is_erronous(pkt)))
0340         return NULL;
0341
0342     if (skb->data + pos > skb_tail_pointer(skb)) {
0343         PKT_ERROR(pkt, "trying to split beyond end of packet\n");
0344         return NULL;
0345     }
0346
0347     /* Create a new packet for the second part of the data */
0348     tmppkt = cfpkt_create_pfx(len2nd + PKT_PREFIX + PKT_POSTFIX,
0349                   PKT_PREFIX);
0350     if (tmppkt == NULL)
0351         return NULL;
0352     skb2 = pkt_to_skb(tmppkt);
0353
0354
0355     if (skb2 == NULL)
0356         return NULL;
0357
0358     skb_put_data(skb2, split, len2nd);
0359
0360     /* Reduce the length of the original packet */
0361     skb_trim(skb, pos);
0362
0363     skb2->priority = skb->priority;
0364     return skb_to_pkt(skb2);
0365 }
0366
0367 bool cfpkt_erroneous(struct cfpkt *pkt)
0368 {
0369     return cfpkt_priv(pkt)->erronous;
0370 }
0371
0372 struct caif_payload_info *cfpkt_info(struct cfpkt *pkt)
0373 {
0374     return (struct caif_payload_info *)&pkt_to_skb(pkt)->cb;
0375 }
0376 EXPORT_SYMBOL(cfpkt_info);
0377
0378 void cfpkt_set_prio(struct cfpkt *pkt, int prio)
0379 {
0380     pkt_to_skb(pkt)->priority = prio;
0381 }
0382 EXPORT_SYMBOL(cfpkt_set_prio);