diff options
| -rw-r--r-- | include/linux/skbuff.h | 111 | ||||
| -rw-r--r-- | net/Kconfig | 3 | ||||
| -rw-r--r-- | net/core/skbuff.c | 155 | ||||
| -rw-r--r-- | net/ipv4/ip_output.c | 1 | ||||
| -rw-r--r-- | net/ipv6/ip6_output.c | 1 |
5 files changed, 270 insertions, 1 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index b1831a5ca173..88f7541837e3 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -245,6 +245,7 @@ struct iov_iter; struct napi_struct; struct bpf_prog; union bpf_attr; +struct skb_ext; #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE) struct nf_conntrack { @@ -636,6 +637,7 @@ typedef unsigned char *sk_buff_data_t; * @queue_mapping: Queue mapping for multiqueue devices * @xmit_more: More SKBs are pending for this queue * @pfmemalloc: skbuff was allocated from PFMEMALLOC reserves + * @active_extensions: active extensions (skb_ext_id types) * @ndisc_nodetype: router type (from link layer) * @ooo_okay: allow the mapping of a socket to a queue to be changed * @l4_hash: indicate hash is a canonical 4-tuple hash over transport @@ -665,6 +667,7 @@ typedef unsigned char *sk_buff_data_t; * @data: Data head pointer * @truesize: Buffer size * @users: User count - see {datagram,tcp}.c + * @extensions: allocated extensions, valid if active_extensions is nonzero */ struct sk_buff { @@ -747,7 +750,9 @@ struct sk_buff { head_frag:1, xmit_more:1, pfmemalloc:1; - +#ifdef CONFIG_SKB_EXTENSIONS + __u8 active_extensions; +#endif /* fields enclosed in headers_start/headers_end are copied * using a single memcpy() in __copy_skb_header() */ @@ -869,6 +874,11 @@ struct sk_buff { *data; unsigned int truesize; refcount_t users; + +#ifdef CONFIG_SKB_EXTENSIONS + /* only useable after checking ->active_extensions != 0 */ + struct skb_ext *extensions; +#endif }; #ifdef __KERNEL__ @@ -3896,6 +3906,105 @@ static inline void nf_conntrack_get(struct nf_conntrack *nfct) atomic_inc(&nfct->use); } #endif + +#ifdef CONFIG_SKB_EXTENSIONS +enum skb_ext_id { +#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) + SKB_EXT_BRIDGE_NF, +#endif + SKB_EXT_NUM, /* must be last */ +}; + +/** + * struct skb_ext - sk_buff extensions + * @refcnt: 1 on allocation, deallocated on 0 + * @offset: offset to add to @data to obtain extension address + * @chunks: size currently allocated, stored in SKB_EXT_ALIGN_SHIFT units + * @data: start of extension data, variable sized + * + * Note: offsets/lengths are stored in chunks of 8 bytes, this allows + * to use 'u8' types while allowing up to 2kb worth of extension data. + */ +struct skb_ext { + refcount_t refcnt; + u8 offset[SKB_EXT_NUM]; /* in chunks of 8 bytes */ + u8 chunks; /* same */ + char data[0] __aligned(8); +}; + +void *skb_ext_add(struct sk_buff *skb, enum skb_ext_id id); +void __skb_ext_del(struct sk_buff *skb, enum skb_ext_id id); +void __skb_ext_put(struct skb_ext *ext); + +static inline void skb_ext_put(struct sk_buff *skb) +{ + if (skb->active_extensions) + __skb_ext_put(skb->extensions); +} + +static inline void skb_ext_get(struct sk_buff *skb) +{ + if (skb->active_extensions) { + struct skb_ext *ext = skb->extensions; + + if (ext) + refcount_inc(&ext->refcnt); + } +} + +static inline void __skb_ext_copy(struct sk_buff *dst, + const struct sk_buff *src) +{ + dst->active_extensions = src->active_extensions; + + if (src->active_extensions) { + struct skb_ext *ext = src->extensions; + + refcount_inc(&ext->refcnt); + dst->extensions = ext; + } +} + +static inline void skb_ext_copy(struct sk_buff *dst, const struct sk_buff *src) +{ + skb_ext_put(dst); + __skb_ext_copy(dst, src); +} + +static inline bool __skb_ext_exist(const struct skb_ext *ext, enum skb_ext_id i) +{ + return !!ext->offset[i]; +} + +static inline bool skb_ext_exist(const struct sk_buff *skb, enum skb_ext_id id) +{ + return skb->active_extensions & (1 << id); +} + +static inline void skb_ext_del(struct sk_buff *skb, enum skb_ext_id id) +{ + if (skb_ext_exist(skb, id)) + __skb_ext_del(skb, id); +} + +static inline void *skb_ext_find(const struct sk_buff *skb, enum skb_ext_id id) +{ + if (skb_ext_exist(skb, id)) { + struct skb_ext *ext = skb->extensions; + + return (void *)ext + (ext->offset[id] << 3); + } + + return NULL; +} +#else +static inline void skb_ext_put(struct sk_buff *skb) {} +static inline void skb_ext_get(struct sk_buff *skb) {} +static inline void skb_ext_del(struct sk_buff *skb, int unused) {} +static inline void __skb_ext_copy(struct sk_buff *d, const struct sk_buff *s) {} +static inline void skb_ext_copy(struct sk_buff *dst, const struct sk_buff *s) {} +#endif /* CONFIG_SKB_EXTENSIONS */ + #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge) { diff --git a/net/Kconfig b/net/Kconfig index f235edb593ba..93b291292860 100644 --- a/net/Kconfig +++ b/net/Kconfig @@ -51,6 +51,9 @@ config NET_INGRESS config NET_EGRESS bool +config SKB_EXTENSIONS + bool + menu "Networking options" source "net/packet/Kconfig" diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 40552547c69a..d2dfad33e686 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -79,6 +79,9 @@ struct kmem_cache *skbuff_head_cache __ro_after_init; static struct kmem_cache *skbuff_fclone_cache __ro_after_init; +#ifdef CONFIG_SKB_EXTENSIONS +static struct kmem_cache *skbuff_ext_cache __ro_after_init; +#endif int sysctl_max_skb_frags __read_mostly = MAX_SKB_FRAGS; EXPORT_SYMBOL(sysctl_max_skb_frags); @@ -617,6 +620,7 @@ void skb_release_head_state(struct sk_buff *skb) #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) nf_bridge_put(skb->nf_bridge); #endif + skb_ext_put(skb); } /* Free everything but the sk_buff shell. */ @@ -796,6 +800,7 @@ static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old) new->dev = old->dev; memcpy(new->cb, old->cb, sizeof(old->cb)); skb_dst_copy(new, old); + __skb_ext_copy(new, old); #ifdef CONFIG_XFRM new->sp = secpath_get(old->sp); #endif @@ -3902,6 +3907,40 @@ done: } EXPORT_SYMBOL_GPL(skb_gro_receive); +#ifdef CONFIG_SKB_EXTENSIONS +#define SKB_EXT_ALIGN_VALUE 8 +#define SKB_EXT_CHUNKSIZEOF(x) (ALIGN((sizeof(x)), SKB_EXT_ALIGN_VALUE) / SKB_EXT_ALIGN_VALUE) + +static const u8 skb_ext_type_len[] = { +#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) + [SKB_EXT_BRIDGE_NF] = SKB_EXT_CHUNKSIZEOF(struct nf_bridge_info), +#endif +}; + +static __always_inline unsigned int skb_ext_total_length(void) +{ + return SKB_EXT_CHUNKSIZEOF(struct skb_ext) + +#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) + skb_ext_type_len[SKB_EXT_BRIDGE_NF] + +#endif + 0; +} + +static void skb_extensions_init(void) +{ + BUILD_BUG_ON(SKB_EXT_NUM >= 8); + BUILD_BUG_ON(skb_ext_total_length() > 255); + + skbuff_ext_cache = kmem_cache_create("skbuff_ext_cache", + SKB_EXT_ALIGN_VALUE * skb_ext_total_length(), + 0, + SLAB_HWCACHE_ALIGN|SLAB_PANIC, + NULL); +} +#else +static void skb_extensions_init(void) {} +#endif + void __init skb_init(void) { skbuff_head_cache = kmem_cache_create_usercopy("skbuff_head_cache", @@ -3916,6 +3955,7 @@ void __init skb_init(void) 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); + skb_extensions_init(); } static int @@ -5554,3 +5594,118 @@ void skb_condense(struct sk_buff *skb) */ skb->truesize = SKB_TRUESIZE(skb_end_offset(skb)); } + +#ifdef CONFIG_SKB_EXTENSIONS +static void *skb_ext_get_ptr(struct skb_ext *ext, enum skb_ext_id id) +{ + return (void *)ext + (ext->offset[id] * SKB_EXT_ALIGN_VALUE); +} + +static struct skb_ext *skb_ext_alloc(void) +{ + struct skb_ext *new = kmem_cache_alloc(skbuff_ext_cache, GFP_ATOMIC); + + if (new) { + memset(new->offset, 0, sizeof(new->offset)); + refcount_set(&new->refcnt, 1); + } + + return new; +} + +static struct skb_ext *skb_ext_maybe_cow(struct skb_ext *old) +{ + struct skb_ext *new; + + if (refcount_read(&old->refcnt) == 1) + return old; + + new = kmem_cache_alloc(skbuff_ext_cache, GFP_ATOMIC); + if (!new) + return NULL; + + memcpy(new, old, old->chunks * SKB_EXT_ALIGN_VALUE); + refcount_set(&new->refcnt, 1); + + __skb_ext_put(old); + return new; +} + +/** + * skb_ext_add - allocate space for given extension, COW if needed + * @skb: buffer + * @id: extension to allocate space for + * + * Allocates enough space for the given extension. + * If the extension is already present, a pointer to that extension + * is returned. + * + * If the skb was cloned, COW applies and the returned memory can be + * modified without changing the extension space of clones buffers. + * + * Returns pointer to the extension or NULL on allocation failure. + */ +void *skb_ext_add(struct sk_buff *skb, enum skb_ext_id id) +{ + struct skb_ext *new, *old = NULL; + unsigned int newlen, newoff; + + if (skb->active_extensions) { + old = skb->extensions; + + new = skb_ext_maybe_cow(old); + if (!new) + return NULL; + + if (__skb_ext_exist(old, id)) { + if (old != new) + skb->extensions = new; + goto set_active; + } + + newoff = old->chunks; + } else { + newoff = SKB_EXT_CHUNKSIZEOF(*new); + + new = skb_ext_alloc(); + if (!new) + return NULL; + } + + newlen = newoff + skb_ext_type_len[id]; + new->chunks = newlen; + new->offset[id] = newoff; + skb->extensions = new; +set_active: + skb->active_extensions |= 1 << id; + return skb_ext_get_ptr(new, id); +} +EXPORT_SYMBOL(skb_ext_add); + +void __skb_ext_del(struct sk_buff *skb, enum skb_ext_id id) +{ + struct skb_ext *ext = skb->extensions; + + skb->active_extensions &= ~(1 << id); + if (skb->active_extensions == 0) { + skb->extensions = NULL; + __skb_ext_put(ext); + } +} +EXPORT_SYMBOL(__skb_ext_del); + +void __skb_ext_put(struct skb_ext *ext) +{ + /* If this is last clone, nothing can increment + * it after check passes. Avoids one atomic op. + */ + if (refcount_read(&ext->refcnt) == 1) + goto free_now; + + if (!refcount_dec_and_test(&ext->refcnt)) + return; +free_now: + kmem_cache_free(skbuff_ext_cache, ext); +} +EXPORT_SYMBOL(__skb_ext_put); +#endif /* CONFIG_SKB_EXTENSIONS */ diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index ab6618036afe..c80188875f39 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -533,6 +533,7 @@ static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) to->tc_index = from->tc_index; #endif nf_copy(to, from); + skb_ext_copy(to, from); #if IS_ENABLED(CONFIG_IP_VS) to->ipvs_property = from->ipvs_property; #endif diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 9d55ee33b7f9..703a8e801c5c 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -581,6 +581,7 @@ static void ip6_copy_metadata(struct sk_buff *to, struct sk_buff *from) to->tc_index = from->tc_index; #endif nf_copy(to, from); + skb_ext_copy(to, from); skb_copy_secmark(to, from); } |