/* $KAME: uipc_mbuf2.c,v 1.31 2001/11/28 11:08:53 itojun Exp $ */ /* $NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej Exp $ */ /*- * Copyright (C) 1999 WIDE Project. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the project nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /*- * Copyright (c) 1982, 1986, 1988, 1991, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95 */ #include <sys/cdefs.h> __FBSDID("$FreeBSD: stable/11/sys/kern/uipc_mbuf2.c 312441 2017-01-19 23:42:51Z rpokala $"); /*#define PULLDOWN_DEBUG*/ #ifdef __HAIKU__ #define FBSD_DRIVER #endif #include <sys/param.h> #include <sys/systm.h> #include <sys/kernel.h> #include <sys/lock.h> #include <sys/malloc.h> #include <sys/mbuf.h> #include <sys/mutex.h> #include <security/mac/mac_framework.h> static MALLOC_DEFINE(M_PACKET_TAGS, MBUF_TAG_MEM_NAME, "packet-attached information"); /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */ static struct mbuf *m_dup1(struct mbuf *, int, int, int); /* * ensure that [off, off + len) is contiguous on the mbuf chain "m". * packet chain before "off" is kept untouched. * if offp == NULL, the target will start at <retval, 0> on resulting chain. * if offp != NULL, the target will start at <retval, *offp> on resulting chain. * * on error return (NULL return value), original "m" will be freed. * * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf. */ struct mbuf * m_pulldown(struct mbuf *m, int off, int len, int *offp) { struct mbuf *n, *o; int hlen, tlen, olen; int writable; /* check invalid arguments. */ if (m == NULL) panic("m == NULL in m_pulldown()"); if (len > MCLBYTES) { m_freem(m); return NULL; /* impossible */ } #ifdef PULLDOWN_DEBUG { struct mbuf *t; printf("before:"); for (t = m; t; t = t->m_next) printf(" %d", t->m_len); printf("\n"); } #endif n = m; while (n != NULL && off > 0) { if (n->m_len > off) break; off -= n->m_len; n = n->m_next; } /* be sure to point non-empty mbuf */ while (n != NULL && n->m_len == 0) n = n->m_next; if (!n) { m_freem(m); return NULL; /* mbuf chain too short */ } /* * The following comment is dated but still partially applies: * * XXX: This code is flawed because it considers a "writable" mbuf * data region to require all of the following: * (i) mbuf _has_ to have M_EXT set; if it is just a regular * mbuf, it is still not considered "writable." * (ii) since mbuf has M_EXT, the ext_type _has_ to be * EXT_CLUSTER. Anything else makes it non-writable. * (iii) M_WRITABLE() must evaluate true. * Ideally, the requirement should only be (iii). * * If we're writable, we're sure we're writable, because the ref. count * cannot increase from 1, as that would require possession of mbuf * n by someone else (which is impossible). However, if we're _not_ * writable, we may eventually become writable )if the ref. count drops * to 1), but we'll fail to notice it unless we re-evaluate * M_WRITABLE(). For now, we only evaluate once at the beginning and * live with this. */ writable = 0; if ((n->m_flags & M_EXT) == 0 || (n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n))) writable = 1; /* * the target data is on <n, off>. * if we got enough data on the mbuf "n", we're done. */ if ((off == 0 || offp) && len <= n->m_len - off) goto ok; /* * when len <= n->m_len - off and off != 0, it is a special case. * len bytes from <n, off> sits in single mbuf, but the caller does * not like the starting position (off). * chop the current mbuf into two pieces, set off to 0. */ if (len <= n->m_len - off) { o = m_dup1(n, off, n->m_len - off, M_NOWAIT); if (o == NULL) { m_freem(m); return NULL; /* ENOBUFS */ } n->m_len = off; o->m_next = n->m_next; n->m_next = o; n = n->m_next; off = 0; goto ok; } /* * we need to take hlen from <n, off> and tlen from <n->m_next, 0>, * and construct contiguous mbuf with m_len == len. * note that hlen + tlen == len, and tlen > 0. */ hlen = n->m_len - off; tlen = len - hlen; /* * ensure that we have enough trailing data on mbuf chain. * if not, we can do nothing about the chain. */ olen = 0; for (o = n->m_next; o != NULL; o = o->m_next) olen += o->m_len; if (hlen + olen < len) { m_freem(m); return NULL; /* mbuf chain too short */ } /* * easy cases first. * we need to use m_copydata() to get data from <n->m_next, 0>. */ if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen && writable) { m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len); n->m_len += tlen; m_adj(n->m_next, tlen); goto ok; } if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen && writable) { n->m_next->m_data -= hlen; n->m_next->m_len += hlen; bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen); n->m_len -= hlen; n = n->m_next; off = 0; goto ok; } /* * now, we need to do the hard way. don't m_copy as there's no room * on both end. */ if (len > MLEN) o = m_getcl(M_NOWAIT, m->m_type, 0); else o = m_get(M_NOWAIT, m->m_type); if (!o) { m_freem(m); return NULL; /* ENOBUFS */ } /* get hlen from <n, off> into <o, 0> */ o->m_len = hlen; bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen); n->m_len -= hlen; /* get tlen from <n->m_next, 0> into <o, hlen> */ m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len); o->m_len += tlen; m_adj(n->m_next, tlen); o->m_next = n->m_next; n->m_next = o; n = o; off = 0; ok: #ifdef PULLDOWN_DEBUG { struct mbuf *t; printf("after:"); for (t = m; t; t = t->m_next) printf("%c%d", t == n ? '*' : ' ', t->m_len); printf(" (off=%d)\n", off); } #endif if (offp) *offp = off; return n; } static struct mbuf * m_dup1(struct mbuf *m, int off, int len, int wait) { struct mbuf *n; int copyhdr; if (len > MCLBYTES) return NULL; if (off == 0 && (m->m_flags & M_PKTHDR) != 0) copyhdr = 1; else copyhdr = 0; if (len >= MINCLSIZE) { if (copyhdr == 1) n = m_getcl(wait, m->m_type, M_PKTHDR); else n = m_getcl(wait, m->m_type, 0); } else { if (copyhdr == 1) n = m_gethdr(wait, m->m_type); else n = m_get(wait, m->m_type); } if (!n) return NULL; /* ENOBUFS */ if (copyhdr && !m_dup_pkthdr(n, m, wait)) { m_free(n); return NULL; } m_copydata(m, off, len, mtod(n, caddr_t)); n->m_len = len; return n; } /* Free a packet tag. */ void m_tag_free_default(struct m_tag *t) { #ifdef MAC if (t->m_tag_id == PACKET_TAG_MACLABEL) mac_mbuf_tag_destroy(t); #endif free(t, M_PACKET_TAGS); } /* Get a packet tag structure along with specified data following. */ struct m_tag * m_tag_alloc(uint32_t cookie, int type, int len, int wait) { struct m_tag *t; MBUF_CHECKSLEEP(wait); if (len < 0) return NULL; t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait); if (t == NULL) return NULL; m_tag_setup(t, cookie, type, len); t->m_tag_free = m_tag_free_default; return t; } /* Unlink and free a packet tag. */ void m_tag_delete(struct mbuf *m, struct m_tag *t) { KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t)); m_tag_unlink(m, t); m_tag_free(t); } /* Unlink and free a packet tag chain, starting from given tag. */ void m_tag_delete_chain(struct mbuf *m, struct m_tag *t) { struct m_tag *p, *q; KASSERT(m, ("m_tag_delete_chain: null mbuf")); if (t != NULL) p = t; else p = SLIST_FIRST(&m->m_pkthdr.tags); if (p == NULL) return; while ((q = SLIST_NEXT(p, m_tag_link)) != NULL) m_tag_delete(m, q); m_tag_delete(m, p); } /* * Strip off all tags that would normally vanish when * passing through a network interface. Only persistent * tags will exist after this; these are expected to remain * so long as the mbuf chain exists, regardless of the * path the mbufs take. */ void m_tag_delete_nonpersistent(struct mbuf *m) { struct m_tag *p, *q; SLIST_FOREACH_SAFE(p, &m->m_pkthdr.tags, m_tag_link, q) if ((p->m_tag_id & MTAG_PERSISTENT) == 0) m_tag_delete(m, p); } /* Find a tag, starting from a given position. */ struct m_tag * m_tag_locate(struct mbuf *m, uint32_t cookie, int type, struct m_tag *t) { struct m_tag *p; KASSERT(m, ("m_tag_locate: null mbuf")); if (t == NULL) p = SLIST_FIRST(&m->m_pkthdr.tags); else p = SLIST_NEXT(t, m_tag_link); while (p != NULL) { if (p->m_tag_cookie == cookie && p->m_tag_id == type) return p; p = SLIST_NEXT(p, m_tag_link); } return NULL; } /* Copy a single tag. */ struct m_tag * m_tag_copy(struct m_tag *t, int how) { struct m_tag *p; MBUF_CHECKSLEEP(how); KASSERT(t, ("m_tag_copy: null tag")); p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how); if (p == NULL) return (NULL); #ifdef MAC /* * XXXMAC: we should probably pass off the initialization, and * copying here? can we hide that PACKET_TAG_MACLABEL is * special from the mbuf code? */ if (t->m_tag_id == PACKET_TAG_MACLABEL) { if (mac_mbuf_tag_init(p, how) != 0) { m_tag_free(p); return (NULL); } mac_mbuf_tag_copy(t, p); } else #endif bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */ return p; } /* * Copy two tag chains. The destination mbuf (to) loses any attached * tags even if the operation fails. This should not be a problem, as * m_tag_copy_chain() is typically called with a newly-allocated * destination mbuf. */ int m_tag_copy_chain(struct mbuf *to, const struct mbuf *from, int how) { struct m_tag *p, *t, *tprev = NULL; MBUF_CHECKSLEEP(how); KASSERT(to && from, ("m_tag_copy_chain: null argument, to %p from %p", to, from)); m_tag_delete_chain(to, NULL); SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) { t = m_tag_copy(p, how); if (t == NULL) { m_tag_delete_chain(to, NULL); return 0; } if (tprev == NULL) SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link); else SLIST_INSERT_AFTER(tprev, t, m_tag_link); tprev = t; } return 1; }
