/*
- * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2000-2015 Apple Inc. All rights reserved.
*
- * @APPLE_LICENSE_HEADER_START@
- *
- * Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved.
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
- * compliance with the License. Please obtain a copy of the License at
- * http://www.opensource.apple.com/apsl/ and read it before using this
- * file.
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
+ *
+ * Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* Please see the License for the specific language governing rights and
* limitations under the License.
*
- * @APPLE_LICENSE_HEADER_END@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*
*
* @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95
*/
+/*
+ * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
+ * support for mandatory and extensible security protections. This notice
+ * is included in support of clause 2.2 (b) of the Apple Public License,
+ * Version 2.0.
+ */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/time.h>
-#include <sys/mount.h>
-#include <sys/vnode.h>
+#include <sys/mount_internal.h>
+#include <sys/vnode_internal.h>
+#include <miscfs/specfs/specdev.h>
#include <sys/namei.h>
#include <sys/errno.h>
#include <sys/malloc.h>
+#include <sys/kauth.h>
+#include <sys/user.h>
+#include <sys/paths.h>
+
+#if CONFIG_MACF
+#include <security/mac_framework.h>
+#endif
/*
* Name caching works as follows:
* If it is a "negative" entry, (i.e. for a name that is known NOT to
* exist) the vnode pointer will be NULL.
*
- * For simplicity (and economy of storage), names longer than
- * a maximum length of NCHNAMLEN are not cached; they occur
- * infrequently in any case, and are almost never of interest.
- *
* Upon reaching the last segment of a path, if the reference
* is for DELETE, or NOCACHE is set (rewrite), and the
* name is located in the cache, it will be dropped.
/*
* Structures associated with name cacheing.
*/
-#define NCHHASH(dvp, cnp) \
- (&nchashtbl[((dvp)->v_id + (cnp)->cn_hash) & nchash])
+
LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */
+u_long nchashmask;
u_long nchash; /* size of hash table - 1 */
long numcache; /* number of cache entries allocated */
-TAILQ_HEAD(, namecache) nclruhead; /* LRU chain */
+int desiredNodes;
+int desiredNegNodes;
+int ncs_negtotal;
+int nc_disabled = 0;
+TAILQ_HEAD(, namecache) nchead; /* chain of all name cache entries */
+TAILQ_HEAD(, namecache) neghead; /* chain of only negative cache entries */
+
+
+#if COLLECT_STATS
+
struct nchstats nchstats; /* cache effectiveness statistics */
-u_long nextvnodeid = 0;
-int doingcache = 1; /* 1 => enable the cache */
-/*
- * Delete an entry from its hash list and move it to the front
- * of the LRU list for immediate reuse.
- */
-#if DIAGNOSTIC
-#define PURGE(ncp) { \
- if (ncp->nc_hash.le_prev == 0) \
- panic("namecache purge le_prev"); \
- if (ncp->nc_hash.le_next == ncp) \
- panic("namecache purge le_next"); \
- LIST_REMOVE(ncp, nc_hash); \
- ncp->nc_hash.le_prev = 0; \
- TAILQ_REMOVE(&nclruhead, ncp, nc_lru); \
- TAILQ_INSERT_HEAD(&nclruhead, ncp, nc_lru); \
+#define NCHSTAT(v) { \
+ nchstats.v++; \
}
+#define NAME_CACHE_LOCK() name_cache_lock()
+#define NAME_CACHE_UNLOCK() name_cache_unlock()
+#define NAME_CACHE_LOCK_SHARED() name_cache_lock()
+
#else
-#define PURGE(ncp) { \
- LIST_REMOVE(ncp, nc_hash); \
- ncp->nc_hash.le_prev = 0; \
- TAILQ_REMOVE(&nclruhead, ncp, nc_lru); \
- TAILQ_INSERT_HEAD(&nclruhead, ncp, nc_lru); \
-}
-#endif /* DIAGNOSTIC */
+#define NCHSTAT(v)
+#define NAME_CACHE_LOCK() name_cache_lock()
+#define NAME_CACHE_UNLOCK() name_cache_unlock()
+#define NAME_CACHE_LOCK_SHARED() name_cache_lock_shared()
+
+#endif
+
+
+/* vars for name cache list lock */
+lck_grp_t * namecache_lck_grp;
+lck_grp_attr_t * namecache_lck_grp_attr;
+lck_attr_t * namecache_lck_attr;
+
+lck_grp_t * strcache_lck_grp;
+lck_grp_attr_t * strcache_lck_grp_attr;
+lck_attr_t * strcache_lck_attr;
+
+lck_rw_t * namecache_rw_lock;
+lck_rw_t * strtable_rw_lock;
+
+#define NUM_STRCACHE_LOCKS 1024
+
+lck_mtx_t strcache_mtx_locks[NUM_STRCACHE_LOCKS];
+
+
+static vnode_t cache_lookup_locked(vnode_t dvp, struct componentname *cnp);
+static const char *add_name_internal(const char *, uint32_t, u_int, boolean_t, u_int);
+static void init_string_table(void);
+static void cache_delete(struct namecache *, int);
+static void cache_enter_locked(vnode_t dvp, vnode_t vp, struct componentname *cnp, const char *strname);
+
+#ifdef DUMP_STRING_TABLE
/*
- * Move an entry that has been used to the tail of the LRU list
- * so that it will be preserved for future use.
+ * Internal dump function used for debugging
*/
-#define TOUCH(ncp) { \
- if (ncp->nc_lru.tqe_next != 0) { \
- TAILQ_REMOVE(&nclruhead, ncp, nc_lru); \
- TAILQ_INSERT_TAIL(&nclruhead, ncp, nc_lru); \
- } \
-}
+void dump_string_table(void);
+#endif /* DUMP_STRING_TABLE */
+
+static void init_crc32(void);
+static unsigned int crc32tab[256];
+
+
+#define NCHHASH(dvp, hash_val) \
+ (&nchashtbl[(dvp->v_id ^ (hash_val)) & nchashmask])
/*
- * Lookup an entry in the cache
+ * This function tries to check if a directory vp is a subdirectory of dvp
+ * only from valid v_parent pointers. It is called with the name cache lock
+ * held and does not drop the lock anytime inside the function.
*
- * We don't do this if the segment name is long, simply so the cache
- * can avoid holding long names (which would either waste space, or
- * add greatly to the complexity).
+ * It returns a boolean that indicates whether or not it was able to
+ * successfully infer the parent/descendent relationship via the v_parent
+ * pointers, or if it could not infer such relationship and that the decision
+ * must be delegated to the owning filesystem.
+ *
+ * If it does not defer the decision, i.e. it was successfuly able to determine
+ * the parent/descendent relationship, *is_subdir tells the caller if vp is a
+ * subdirectory of dvp.
+ *
+ * If the decision is deferred, *next_vp is where it stopped i.e. *next_vp
+ * is the vnode whose parent is to be determined from the filesystem.
+ * *is_subdir, in this case, is not indicative of anything and should be
+ * ignored.
+ *
+ * The return value and output args should be used as follows :
+ *
+ * defer = cache_check_vnode_issubdir(vp, dvp, is_subdir, next_vp);
+ * if (!defer) {
+ * if (*is_subdir)
+ * vp is subdirectory;
+ * else
+ * vp is not a subdirectory;
+ * } else {
+ * if (*next_vp)
+ * check this vnode's parent from the filesystem
+ * else
+ * error (likely because of forced unmount).
+ * }
*
- * Lookup is called with dvp pointing to the directory to search,
- * cnp pointing to the name of the entry being sought. If the lookup
- * succeeds, the vnode is returned in *vpp, and a status of -1 is
- * returned. If the lookup determines that the name does not exist
- * (negative cacheing), a status of ENOENT is returned. If the lookup
- * fails, a status of zero is returned.
*/
-
-int
-cache_lookup(dvp, vpp, cnp)
- struct vnode *dvp;
- struct vnode **vpp;
- struct componentname *cnp;
+static boolean_t
+cache_check_vnode_issubdir(vnode_t vp, vnode_t dvp, boolean_t *is_subdir,
+ vnode_t *next_vp)
{
- register struct namecache *ncp, *nnp;
- register struct nchashhead *ncpp;
+ vnode_t tvp = vp;
+ int defer = FALSE;
- if (!doingcache) {
- cnp->cn_flags &= ~MAKEENTRY;
- return (0);
- }
- if (cnp->cn_namelen > NCHNAMLEN) {
- nchstats.ncs_long++;
- cnp->cn_flags &= ~MAKEENTRY;
- return (0);
- }
+ *is_subdir = FALSE;
+ *next_vp = NULLVP;
+ while (1) {
+ mount_t tmp;
- ncpp = NCHHASH(dvp, cnp);
- for (ncp = ncpp->lh_first; ncp != 0; ncp = nnp) {
- nnp = ncp->nc_hash.le_next;
- /* If one of the vp's went stale, don't bother anymore. */
- if ((ncp->nc_dvpid != ncp->nc_dvp->v_id) ||
- (ncp->nc_vp && ncp->nc_vpid != ncp->nc_vp->v_id)) {
- nchstats.ncs_falsehits++;
- PURGE(ncp);
- continue;
- }
- /* Now that we know the vp's to be valid, is it ours ? */
- if (ncp->nc_dvp == dvp &&
- ncp->nc_nlen == cnp->cn_namelen &&
- !bcmp(ncp->nc_name, cnp->cn_nameptr, (u_int)ncp->nc_nlen))
+ if (tvp == dvp) {
+ *is_subdir = TRUE;
break;
- }
+ } else if (tvp == rootvnode) {
+ /* *is_subdir = FALSE */
+ break;
+ }
- /* We failed to find an entry */
- if (ncp == 0) {
- nchstats.ncs_miss++;
- return (0);
- }
+ tmp = tvp->v_mount;
+ while ((tvp->v_flag & VROOT) && tmp && tmp->mnt_vnodecovered &&
+ tvp != dvp && tvp != rootvnode) {
+ tvp = tmp->mnt_vnodecovered;
+ tmp = tvp->v_mount;
+ }
- /* We don't want to have an entry, so dump it */
- if ((cnp->cn_flags & MAKEENTRY) == 0) {
- nchstats.ncs_badhits++;
- PURGE(ncp);
- return (0);
- }
+ /*
+ * If dvp is not at the top of a mount "stack" then
+ * vp is not a subdirectory of dvp either.
+ */
+ if (tvp == dvp || tvp == rootvnode) {
+ /* *is_subdir = FALSE */
+ break;
+ }
- /* We found a "positive" match, return the vnode */
- if (ncp->nc_vp) {
- nchstats.ncs_goodhits++;
- TOUCH(ncp);
- *vpp = ncp->nc_vp;
- return (-1);
- }
+ if (!tmp) {
+ defer = TRUE;
+ *next_vp = NULLVP;
+ break;
+ }
- /* We found a negative match, and want to create it, so purge */
- if (cnp->cn_nameiop == CREATE) {
- nchstats.ncs_badhits++;
- PURGE(ncp);
- return (0);
+ if ((tvp->v_flag & VISHARDLINK) || !(tvp->v_parent)) {
+ defer = TRUE;
+ *next_vp = tvp;
+ break;
+ }
+
+ tvp = tvp->v_parent;
}
+ return (defer);
+}
+
+/* maximum times retry from potentially transient errors in vnode_issubdir */
+#define MAX_ERROR_RETRY 3
+
+/*
+ * This function checks if a given directory (vp) is a subdirectory of dvp.
+ * It walks backwards from vp and if it hits dvp in its parent chain,
+ * it is a subdirectory. If it encounters the root directory, it is not
+ * a subdirectory.
+ *
+ * This function returns an error if it is unsuccessful and 0 on success.
+ *
+ * On entry (and exit) vp has an iocount and if this function has to take
+ * any iocounts on other vnodes in the parent chain traversal, it releases them.
+ */
+int
+vnode_issubdir(vnode_t vp, vnode_t dvp, int *is_subdir, vfs_context_t ctx)
+{
+ vnode_t start_vp, tvp;
+ vnode_t vp_with_iocount;
+ int error = 0;
+ char dotdotbuf[] = "..";
+ int error_retry_count = 0; /* retry count for potentially transient
+ errors */
+
+ *is_subdir = FALSE;
+ tvp = start_vp = vp;
/*
- * We found a "negative" match, ENOENT notifies client of this match.
- * The nc_vpid field records whether this is a whiteout.
+ * Anytime we acquire an iocount in this function, we save the vnode
+ * in this variable and release it before exiting.
*/
- nchstats.ncs_neghits++;
- TOUCH(ncp);
- cnp->cn_flags |= ncp->nc_vpid;
- return (ENOENT);
+ vp_with_iocount = NULLVP;
+
+ while (1) {
+ boolean_t defer;
+ vnode_t pvp;
+ uint32_t vid;
+ struct componentname cn;
+ boolean_t is_subdir_locked = FALSE;
+
+ if (tvp == dvp) {
+ *is_subdir = TRUE;
+ break;
+ } else if (tvp == rootvnode) {
+ /* *is_subdir = FALSE */
+ break;
+ }
+
+ NAME_CACHE_LOCK_SHARED();
+
+ defer = cache_check_vnode_issubdir(tvp, dvp, &is_subdir_locked,
+ &tvp);
+
+ if (defer && tvp)
+ vid = vnode_vid(tvp);
+
+ NAME_CACHE_UNLOCK();
+
+ if (!defer) {
+ *is_subdir = is_subdir_locked;
+ break;
+ }
+
+ if (!tvp) {
+ if (error_retry_count++ < MAX_ERROR_RETRY) {
+ tvp = vp;
+ continue;
+ }
+ error = ENOENT;
+ break;
+ }
+
+ if (tvp != start_vp) {
+ if (vp_with_iocount) {
+ vnode_put(vp_with_iocount);
+ vp_with_iocount = NULLVP;
+ }
+
+ error = vnode_getwithvid(tvp, vid);
+ if (error) {
+ if (error_retry_count++ < MAX_ERROR_RETRY) {
+ tvp = vp;
+ error = 0;
+ continue;
+ }
+ break;
+ }
+
+ vp_with_iocount = tvp;
+ }
+
+ bzero(&cn, sizeof(cn));
+ cn.cn_nameiop = LOOKUP;
+ cn.cn_flags = ISLASTCN | ISDOTDOT;
+ cn.cn_context = ctx;
+ cn.cn_pnbuf = &dotdotbuf[0];
+ cn.cn_pnlen = sizeof(dotdotbuf);
+ cn.cn_nameptr = cn.cn_pnbuf;
+ cn.cn_namelen = 2;
+
+ pvp = NULLVP;
+ if ((error = VNOP_LOOKUP(tvp, &pvp, &cn, ctx)))
+ break;
+
+ if (!(tvp->v_flag & VISHARDLINK) && tvp->v_parent != pvp) {
+ (void)vnode_update_identity(tvp, pvp, NULL, 0, 0,
+ VNODE_UPDATE_PARENT);
+ }
+
+ if (vp_with_iocount)
+ vnode_put(vp_with_iocount);
+
+ vp_with_iocount = tvp = pvp;
+ }
+
+ if (vp_with_iocount)
+ vnode_put(vp_with_iocount);
+
+ return (error);
}
/*
- * Add an entry to the cache.
+ * This function builds the path to a filename in "buff". The
+ * length of the buffer *INCLUDING* the trailing zero byte is
+ * returned in outlen. NOTE: the length includes the trailing
+ * zero byte and thus the length is one greater than what strlen
+ * would return. This is important and lots of code elsewhere
+ * in the kernel assumes this behavior.
+ *
+ * This function can call vnop in file system if the parent vnode
+ * does not exist or when called for hardlinks via volfs path.
+ * If BUILDPATH_NO_FS_ENTER is set in flags, it only uses values present
+ * in the name cache and does not enter the file system.
+ *
+ * If BUILDPATH_CHECK_MOVED is set in flags, we return EAGAIN when
+ * we encounter ENOENT during path reconstruction. ENOENT means that
+ * one of the parents moved while we were building the path. The
+ * caller can special handle this case by calling build_path again.
+ *
+ * If BUILDPATH_VOLUME_RELATIVE is set in flags, we return path
+ * that is relative to the nearest mount point, i.e. do not
+ * cross over mount points during building the path.
+ *
+ * passed in vp must have a valid io_count reference
*/
-void
-cache_enter(dvp, vp, cnp)
- struct vnode *dvp;
- struct vnode *vp;
- struct componentname *cnp;
+int
+build_path(vnode_t first_vp, char *buff, int buflen, int *outlen, int flags, vfs_context_t ctx)
{
- register struct namecache *ncp;
- register struct nchashhead *ncpp;
+ vnode_t vp, tvp;
+ vnode_t vp_with_iocount;
+ vnode_t proc_root_dir_vp;
+ char *end;
+ const char *str;
+ int len;
+ int ret = 0;
+ int fixhardlink;
- if (!doingcache)
- return;
+ if (first_vp == NULLVP)
+ return (EINVAL);
+
+ if (buflen <= 1)
+ return (ENOSPC);
/*
- * If an entry that is too long, is entered, bad things happen.
- * cache_lookup acts as the sentinel to make sure longer names
- * are not stored. This here will prevent outsiders from doing
- * something that is unexpected.
+ * Grab the process fd so we can evaluate fd_rdir.
*/
- if (cnp->cn_namelen > NCHNAMLEN)
- panic("cache_enter: name too long");
+ if (vfs_context_proc(ctx)->p_fd)
+ proc_root_dir_vp = vfs_context_proc(ctx)->p_fd->fd_rdir;
+ else
+ proc_root_dir_vp = NULL;
+
+ vp_with_iocount = NULLVP;
+again:
+ vp = first_vp;
+
+ end = &buff[buflen-1];
+ *end = '\0';
/*
- * We allocate a new entry if we are less than the maximum
- * allowed and the one at the front of the LRU list is in use.
- * Otherwise we use the one at the front of the LRU list.
+ * holding the NAME_CACHE_LOCK in shared mode is
+ * sufficient to stabilize both the vp->v_parent chain
+ * and the 'vp->v_mount->mnt_vnodecovered' chain
+ *
+ * if we need to drop this lock, we must first grab the v_id
+ * from the vnode we're currently working with... if that
+ * vnode doesn't already have an io_count reference (the vp
+ * passed in comes with one), we must grab a reference
+ * after we drop the NAME_CACHE_LOCK via vnode_getwithvid...
+ * deadlocks may result if you call vnode_get while holding
+ * the NAME_CACHE_LOCK... we lazily release the reference
+ * we pick up the next time we encounter a need to drop
+ * the NAME_CACHE_LOCK or before we return from this routine
*/
- if (numcache < desiredvnodes &&
- ((ncp = nclruhead.tqh_first) == NULL ||
- ncp->nc_hash.le_prev != 0)) {
- /* Add one more entry */
- ncp = (struct namecache *)
- _MALLOC_ZONE((u_long)sizeof *ncp, M_CACHE, M_WAITOK);
- numcache++;
- } else if (ncp = nclruhead.tqh_first) {
- /* reuse an old entry */
- TAILQ_REMOVE(&nclruhead, ncp, nc_lru);
- if (ncp->nc_hash.le_prev != 0) {
-#if DIAGNOSTIC
- if (ncp->nc_hash.le_next == ncp)
- panic("cache_enter: le_next");
-#endif
- LIST_REMOVE(ncp, nc_hash);
- ncp->nc_hash.le_prev = 0;
+ NAME_CACHE_LOCK_SHARED();
+
+ /*
+ * Check if this is the root of a file system.
+ */
+ while (vp && vp->v_flag & VROOT) {
+ if (vp->v_mount == NULL) {
+ ret = EINVAL;
+ goto out_unlock;
+ }
+ if ((vp->v_mount->mnt_flag & MNT_ROOTFS) || (vp == proc_root_dir_vp)) {
+ /*
+ * It's the root of the root file system, so it's
+ * just "/".
+ */
+ *--end = '/';
+
+ goto out_unlock;
+ } else {
+ /*
+ * This the root of the volume and the caller does not
+ * want to cross mount points. Therefore just return
+ * '/' as the relative path.
+ */
+ if (flags & BUILDPATH_VOLUME_RELATIVE) {
+ *--end = '/';
+ goto out_unlock;
+ } else {
+ vp = vp->v_mount->mnt_vnodecovered;
+ }
}
- } else {
- /* give up */
- return;
}
+ while ((vp != NULLVP) && (vp->v_parent != vp)) {
+ int vid;
+
+ /*
+ * For hardlinks the v_name may be stale, so if its OK
+ * to enter a file system, ask the file system for the
+ * name and parent (below).
+ */
+ fixhardlink = (vp->v_flag & VISHARDLINK) &&
+ (vp->v_mount->mnt_kern_flag & MNTK_PATH_FROM_ID) &&
+ !(flags & BUILDPATH_NO_FS_ENTER);
+
+ if (!fixhardlink) {
+ str = vp->v_name;
+
+ if (str == NULL || *str == '\0') {
+ if (vp->v_parent != NULL)
+ ret = EINVAL;
+ else
+ ret = ENOENT;
+ goto out_unlock;
+ }
+ len = strlen(str);
+ /*
+ * Check that there's enough space (including space for the '/')
+ */
+ if ((end - buff) < (len + 1)) {
+ ret = ENOSPC;
+ goto out_unlock;
+ }
+ /*
+ * Copy the name backwards.
+ */
+ str += len;
+
+ for (; len > 0; len--)
+ *--end = *--str;
+ /*
+ * Add a path separator.
+ */
+ *--end = '/';
+ }
+
+ /*
+ * Walk up the parent chain.
+ */
+ if (((vp->v_parent != NULLVP) && !fixhardlink) ||
+ (flags & BUILDPATH_NO_FS_ENTER)) {
+
+ /*
+ * In this if () block we are not allowed to enter the filesystem
+ * to conclusively get the most accurate parent identifier.
+ * As a result, if 'vp' does not identify '/' and it
+ * does not have a valid v_parent, then error out
+ * and disallow further path construction
+ */
+ if ((vp->v_parent == NULLVP) && (rootvnode != vp)) {
+ /*
+ * Only '/' is allowed to have a NULL parent
+ * pointer. Upper level callers should ideally
+ * re-drive name lookup on receiving a ENOENT.
+ */
+ ret = ENOENT;
+
+ /* The code below will exit early if 'tvp = vp' == NULL */
+ }
+ vp = vp->v_parent;
+
+ /*
+ * if the vnode we have in hand isn't a directory and it
+ * has a v_parent, then we started with the resource fork
+ * so skip up to avoid getting a duplicate copy of the
+ * file name in the path.
+ */
+ if (vp && !vnode_isdir(vp) && vp->v_parent) {
+ vp = vp->v_parent;
+ }
+ } else {
+ /*
+ * No parent, go get it if supported.
+ */
+ struct vnode_attr va;
+ vnode_t dvp;
+
+ /*
+ * Make sure file system supports obtaining a path from id.
+ */
+ if (!(vp->v_mount->mnt_kern_flag & MNTK_PATH_FROM_ID)) {
+ ret = ENOENT;
+ goto out_unlock;
+ }
+ vid = vp->v_id;
+
+ NAME_CACHE_UNLOCK();
+
+ if (vp != first_vp && vp != vp_with_iocount) {
+ if (vp_with_iocount) {
+ vnode_put(vp_with_iocount);
+ vp_with_iocount = NULLVP;
+ }
+ if (vnode_getwithvid(vp, vid))
+ goto again;
+ vp_with_iocount = vp;
+ }
+ VATTR_INIT(&va);
+ VATTR_WANTED(&va, va_parentid);
+
+ if (fixhardlink) {
+ VATTR_WANTED(&va, va_name);
+ MALLOC_ZONE(va.va_name, caddr_t, MAXPATHLEN, M_NAMEI, M_WAITOK);
+ } else {
+ va.va_name = NULL;
+ }
+ /*
+ * Ask the file system for its parent id and for its name (optional).
+ */
+ ret = vnode_getattr(vp, &va, ctx);
+
+ if (fixhardlink) {
+ if ((ret == 0) && (VATTR_IS_SUPPORTED(&va, va_name))) {
+ str = va.va_name;
+ vnode_update_identity(vp, NULL, str, strlen(str), 0, VNODE_UPDATE_NAME);
+ } else if (vp->v_name) {
+ str = vp->v_name;
+ ret = 0;
+ } else {
+ ret = ENOENT;
+ goto bad_news;
+ }
+ len = strlen(str);
+
+ /*
+ * Check that there's enough space.
+ */
+ if ((end - buff) < (len + 1)) {
+ ret = ENOSPC;
+ } else {
+ /* Copy the name backwards. */
+ str += len;
+
+ for (; len > 0; len--) {
+ *--end = *--str;
+ }
+ /*
+ * Add a path separator.
+ */
+ *--end = '/';
+ }
+bad_news:
+ FREE_ZONE(va.va_name, MAXPATHLEN, M_NAMEI);
+ }
+ if (ret || !VATTR_IS_SUPPORTED(&va, va_parentid)) {
+ ret = ENOENT;
+ goto out;
+ }
+ /*
+ * Ask the file system for the parent vnode.
+ */
+ if ((ret = VFS_VGET(vp->v_mount, (ino64_t)va.va_parentid, &dvp, ctx)))
+ goto out;
+
+ if (!fixhardlink && (vp->v_parent != dvp))
+ vnode_update_identity(vp, dvp, NULL, 0, 0, VNODE_UPDATE_PARENT);
+
+ if (vp_with_iocount)
+ vnode_put(vp_with_iocount);
+ vp = dvp;
+ vp_with_iocount = vp;
+
+ NAME_CACHE_LOCK_SHARED();
+
+ /*
+ * if the vnode we have in hand isn't a directory and it
+ * has a v_parent, then we started with the resource fork
+ * so skip up to avoid getting a duplicate copy of the
+ * file name in the path.
+ */
+ if (vp && !vnode_isdir(vp) && vp->v_parent)
+ vp = vp->v_parent;
+ }
+
+ if (vp && (flags & BUILDPATH_CHECKACCESS)) {
+ vid = vp->v_id;
+
+ NAME_CACHE_UNLOCK();
+
+ if (vp != first_vp && vp != vp_with_iocount) {
+ if (vp_with_iocount) {
+ vnode_put(vp_with_iocount);
+ vp_with_iocount = NULLVP;
+ }
+ if (vnode_getwithvid(vp, vid))
+ goto again;
+ vp_with_iocount = vp;
+ }
+ if ((ret = vnode_authorize(vp, NULL, KAUTH_VNODE_SEARCH, ctx)))
+ goto out; /* no peeking */
+
+ NAME_CACHE_LOCK_SHARED();
+ }
+
+ /*
+ * When a mount point is crossed switch the vp.
+ * Continue until we find the root or we find
+ * a vnode that's not the root of a mounted
+ * file system.
+ */
+ tvp = vp;
+
+ while (tvp) {
+ if (tvp == proc_root_dir_vp)
+ goto out_unlock; /* encountered the root */
+
+ if (!(tvp->v_flag & VROOT) || !tvp->v_mount)
+ break; /* not the root of a mounted FS */
+
+ if (flags & BUILDPATH_VOLUME_RELATIVE) {
+ /* Do not cross over mount points */
+ tvp = NULL;
+ } else {
+ tvp = tvp->v_mount->mnt_vnodecovered;
+ }
+ }
+ if (tvp == NULLVP)
+ goto out_unlock;
+ vp = tvp;
+ }
+out_unlock:
+ NAME_CACHE_UNLOCK();
+out:
+ if (vp_with_iocount)
+ vnode_put(vp_with_iocount);
/*
- * Fill in cache info, if vp is NULL this is a "negative" cache entry.
- * For negative entries, we have to record whether it is a whiteout.
- * the whiteout flag is stored in the nc_vpid field which is
- * otherwise unused.
+ * Slide the name down to the beginning of the buffer.
*/
- ncp->nc_vp = vp;
- if (vp)
- ncp->nc_vpid = vp->v_id;
- else
- ncp->nc_vpid = cnp->cn_flags & ISWHITEOUT;
- ncp->nc_dvp = dvp;
- ncp->nc_dvpid = dvp->v_id;
- ncp->nc_nlen = cnp->cn_namelen;
- bcopy(cnp->cn_nameptr, ncp->nc_name, (unsigned)ncp->nc_nlen);
- TAILQ_INSERT_TAIL(&nclruhead, ncp, nc_lru);
- ncpp = NCHHASH(dvp, cnp);
-#if DIAGNOSTIC
- {
- register struct namecache *p;
+ memmove(buff, end, &buff[buflen] - end);
- for (p = ncpp->lh_first; p != 0; p = p->nc_hash.le_next)
- if (p == ncp)
- panic("cache_enter: duplicate");
+ /*
+ * length includes the trailing zero byte
+ */
+ *outlen = &buff[buflen] - end;
+
+ /* One of the parents was moved during path reconstruction.
+ * The caller is interested in knowing whether any of the
+ * parents moved via BUILDPATH_CHECK_MOVED, so return EAGAIN.
+ */
+ if ((ret == ENOENT) && (flags & BUILDPATH_CHECK_MOVED)) {
+ ret = EAGAIN;
}
-#endif
- LIST_INSERT_HEAD(ncpp, ncp, nc_hash);
+
+ return (ret);
}
+
/*
- * Name cache initialization, from vfs_init() when we are booting
+ * return NULLVP if vp's parent doesn't
+ * exist, or we can't get a valid iocount
+ * else return the parent of vp
*/
-void
-nchinit()
+vnode_t
+vnode_getparent(vnode_t vp)
+{
+ vnode_t pvp = NULLVP;
+ int pvid;
+
+ NAME_CACHE_LOCK_SHARED();
+ /*
+ * v_parent is stable behind the name_cache lock
+ * however, the only thing we can really guarantee
+ * is that we've grabbed a valid iocount on the
+ * parent of 'vp' at the time we took the name_cache lock...
+ * once we drop the lock, vp could get re-parented
+ */
+ if ( (pvp = vp->v_parent) != NULLVP ) {
+ pvid = pvp->v_id;
+
+ NAME_CACHE_UNLOCK();
+
+ if (vnode_getwithvid(pvp, pvid) != 0)
+ pvp = NULL;
+ } else
+ NAME_CACHE_UNLOCK();
+ return (pvp);
+}
+
+const char *
+vnode_getname(vnode_t vp)
{
+ const char *name = NULL;
+
+ NAME_CACHE_LOCK_SHARED();
+
+ if (vp->v_name)
+ name = vfs_addname(vp->v_name, strlen(vp->v_name), 0, 0);
+ NAME_CACHE_UNLOCK();
- TAILQ_INIT(&nclruhead);
- nchashtbl = hashinit(desiredvnodes, M_CACHE, &nchash);
+ return (name);
}
-/*
- * Invalidate a all entries to particular vnode.
- *
- * We actually just increment the v_id, that will do it. The entries will
- * be purged by lookup as they get found. If the v_id wraps around, we
- * need to ditch the entire cache, to avoid confusion. No valid vnode will
- * ever have (v_id == 0).
- */
void
-cache_purge(vp)
- struct vnode *vp;
+vnode_putname(const char *name)
{
- struct namecache *ncp;
- struct nchashhead *ncpp;
+ vfs_removename(name);
+}
- vp->v_id = ++nextvnodeid;
- if (nextvnodeid != 0)
- return;
- for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) {
- while (ncp = ncpp->lh_first)
- PURGE(ncp);
+static const char unknown_vnodename[] = "(unknown vnode name)";
+
+const char *
+vnode_getname_printable(vnode_t vp)
+{
+ const char *name = vnode_getname(vp);
+ if (name != NULL)
+ return name;
+
+ switch (vp->v_type) {
+ case VCHR:
+ case VBLK:
+ {
+ /*
+ * Create an artificial dev name from
+ * major and minor device number
+ */
+ char dev_name[64];
+ (void) snprintf(dev_name, sizeof(dev_name),
+ "%c(%u, %u)", VCHR == vp->v_type ? 'c':'b',
+ major(vp->v_rdev), minor(vp->v_rdev));
+ /*
+ * Add the newly created dev name to the name
+ * cache to allow easier cleanup. Also,
+ * vfs_addname allocates memory for the new name
+ * and returns it.
+ */
+ NAME_CACHE_LOCK_SHARED();
+ name = vfs_addname(dev_name, strlen(dev_name), 0, 0);
+ NAME_CACHE_UNLOCK();
+ return name;
+ }
+ default:
+ return unknown_vnodename;
}
- vp->v_id = ++nextvnodeid;
}
+void
+vnode_putname_printable(const char *name)
+{
+ if (name == unknown_vnodename)
+ return;
+ vnode_putname(name);
+}
+
+
/*
- * Flush all entries referencing a particular filesystem.
+ * if VNODE_UPDATE_PARENT, and we can take
+ * a reference on dvp, then update vp with
+ * it's new parent... if vp already has a parent,
+ * then drop the reference vp held on it
*
- * Since we need to check it anyway, we will flush all the invalid
- * entriess at the same time.
+ * if VNODE_UPDATE_NAME,
+ * then drop string ref on v_name if it exists, and if name is non-NULL
+ * then pick up a string reference on name and record it in v_name...
+ * optionally pass in the length and hashval of name if known
+ *
+ * if VNODE_UPDATE_CACHE, flush the name cache entries associated with vp
*/
void
-cache_purgevfs(mp)
- struct mount *mp;
+vnode_update_identity(vnode_t vp, vnode_t dvp, const char *name, int name_len, uint32_t name_hashval, int flags)
{
- struct nchashhead *ncpp;
- struct namecache *ncp, *nnp;
+ struct namecache *ncp;
+ vnode_t old_parentvp = NULLVP;
+#if NAMEDSTREAMS
+ int isstream = (vp->v_flag & VISNAMEDSTREAM);
+ int kusecountbumped = 0;
+#endif
+ kauth_cred_t tcred = NULL;
+ const char *vname = NULL;
+ const char *tname = NULL;
- /* Scan hash tables for applicable entries */
- for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) {
- for (ncp = ncpp->lh_first; ncp != 0; ncp = nnp) {
- nnp = ncp->nc_hash.le_next;
- if (ncp->nc_dvpid != ncp->nc_dvp->v_id ||
- (ncp->nc_vp && ncp->nc_vpid != ncp->nc_vp->v_id) ||
- ncp->nc_dvp->v_mount == mp) {
- PURGE(ncp);
+ if (flags & VNODE_UPDATE_PARENT) {
+ if (dvp && vnode_ref(dvp) != 0) {
+ dvp = NULLVP;
+ }
+#if NAMEDSTREAMS
+ /* Don't count a stream's parent ref during unmounts */
+ if (isstream && dvp && (dvp != vp) && (dvp != vp->v_parent) && (dvp->v_type == VREG)) {
+ vnode_lock_spin(dvp);
+ ++dvp->v_kusecount;
+ kusecountbumped = 1;
+ vnode_unlock(dvp);
+ }
+#endif
+ } else {
+ dvp = NULLVP;
+ }
+ if ( (flags & VNODE_UPDATE_NAME) ) {
+ if (name != vp->v_name) {
+ if (name && *name) {
+ if (name_len == 0)
+ name_len = strlen(name);
+ tname = vfs_addname(name, name_len, name_hashval, 0);
+ }
+ } else
+ flags &= ~VNODE_UPDATE_NAME;
+ }
+ if ( (flags & (VNODE_UPDATE_PURGE | VNODE_UPDATE_PARENT | VNODE_UPDATE_CACHE | VNODE_UPDATE_NAME)) ) {
+
+ NAME_CACHE_LOCK();
+
+ if ( (flags & VNODE_UPDATE_PURGE) ) {
+
+ if (vp->v_parent)
+ vp->v_parent->v_nc_generation++;
+
+ while ( (ncp = LIST_FIRST(&vp->v_nclinks)) )
+ cache_delete(ncp, 1);
+
+ while ( (ncp = TAILQ_FIRST(&vp->v_ncchildren)) )
+ cache_delete(ncp, 1);
+
+ /*
+ * Use a temp variable to avoid kauth_cred_unref() while NAME_CACHE_LOCK is held
+ */
+ tcred = vp->v_cred;
+ vp->v_cred = NOCRED;
+ vp->v_authorized_actions = 0;
+ }
+ if ( (flags & VNODE_UPDATE_NAME) ) {
+ vname = vp->v_name;
+ vp->v_name = tname;
+ }
+ if (flags & VNODE_UPDATE_PARENT) {
+ if (dvp != vp && dvp != vp->v_parent) {
+ old_parentvp = vp->v_parent;
+ vp->v_parent = dvp;
+ dvp = NULLVP;
+
+ if (old_parentvp)
+ flags |= VNODE_UPDATE_CACHE;
}
}
+ if (flags & VNODE_UPDATE_CACHE) {
+ while ( (ncp = LIST_FIRST(&vp->v_nclinks)) )
+ cache_delete(ncp, 1);
+ }
+ NAME_CACHE_UNLOCK();
+
+ if (vname != NULL)
+ vfs_removename(vname);
+
+ if (IS_VALID_CRED(tcred))
+ kauth_cred_unref(&tcred);
+ }
+ if (dvp != NULLVP) {
+#if NAMEDSTREAMS
+ /* Back-out the ref we took if we lost a race for vp->v_parent. */
+ if (kusecountbumped) {
+ vnode_lock_spin(dvp);
+ if (dvp->v_kusecount > 0)
+ --dvp->v_kusecount;
+ vnode_unlock(dvp);
+ }
+#endif
+ vnode_rele(dvp);
+ }
+ if (old_parentvp) {
+ struct uthread *ut;
+
+#if NAMEDSTREAMS
+ if (isstream) {
+ vnode_lock_spin(old_parentvp);
+ if ((old_parentvp->v_type != VDIR) && (old_parentvp->v_kusecount > 0))
+ --old_parentvp->v_kusecount;
+ vnode_unlock(old_parentvp);
+ }
+#endif
+ ut = get_bsdthread_info(current_thread());
+
+ /*
+ * indicated to vnode_rele that it shouldn't do a
+ * vnode_reclaim at this time... instead it will
+ * chain the vnode to the uu_vreclaims list...
+ * we'll be responsible for calling vnode_reclaim
+ * on each of the vnodes in this list...
+ */
+ ut->uu_defer_reclaims = 1;
+ ut->uu_vreclaims = NULLVP;
+
+ while ( (vp = old_parentvp) != NULLVP ) {
+
+ vnode_lock_spin(vp);
+ vnode_rele_internal(vp, 0, 0, 1);
+
+ /*
+ * check to see if the vnode is now in the state
+ * that would have triggered a vnode_reclaim in vnode_rele
+ * if it is, we save it's parent pointer and then NULL
+ * out the v_parent field... we'll drop the reference
+ * that was held on the next iteration of this loop...
+ * this short circuits a potential deep recursion if we
+ * have a long chain of parents in this state...
+ * we'll sit in this loop until we run into
+ * a parent in this chain that is not in this state
+ *
+ * make our check and the vnode_rele atomic
+ * with respect to the current vnode we're working on
+ * by holding the vnode lock
+ * if vnode_rele deferred the vnode_reclaim and has put
+ * this vnode on the list to be reaped by us, than
+ * it has left this vnode with an iocount == 1
+ */
+ if ( (vp->v_iocount == 1) && (vp->v_usecount == 0) &&
+ ((vp->v_lflag & (VL_MARKTERM | VL_TERMINATE | VL_DEAD)) == VL_MARKTERM)) {
+ /*
+ * vnode_rele wanted to do a vnode_reclaim on this vnode
+ * it should be sitting on the head of the uu_vreclaims chain
+ * pull the parent pointer now so that when we do the
+ * vnode_reclaim for each of the vnodes in the uu_vreclaims
+ * list, we won't recurse back through here
+ *
+ * need to do a convert here in case vnode_rele_internal
+ * returns with the lock held in the spin mode... it
+ * can drop and retake the lock under certain circumstances
+ */
+ vnode_lock_convert(vp);
+
+ NAME_CACHE_LOCK();
+ old_parentvp = vp->v_parent;
+ vp->v_parent = NULLVP;
+ NAME_CACHE_UNLOCK();
+ } else {
+ /*
+ * we're done... we ran into a vnode that isn't
+ * being terminated
+ */
+ old_parentvp = NULLVP;
+ }
+ vnode_unlock(vp);
+ }
+ ut->uu_defer_reclaims = 0;
+
+ while ( (vp = ut->uu_vreclaims) != NULLVP) {
+ ut->uu_vreclaims = vp->v_defer_reclaimlist;
+
+ /*
+ * vnode_put will drive the vnode_reclaim if
+ * we are still the only reference on this vnode
+ */
+ vnode_put(vp);
+ }
+ }
+}
+
+
+/*
+ * Mark a vnode as having multiple hard links. HFS makes use of this
+ * because it keeps track of each link separately, and wants to know
+ * which link was actually used.
+ *
+ * This will cause the name cache to force a VNOP_LOOKUP on the vnode
+ * so that HFS can post-process the lookup. Also, volfs will call
+ * VNOP_GETATTR2 to determine the parent, instead of using v_parent.
+ */
+void vnode_setmultipath(vnode_t vp)
+{
+ vnode_lock_spin(vp);
+
+ /*
+ * In theory, we're changing the vnode's identity as far as the
+ * name cache is concerned, so we ought to grab the name cache lock
+ * here. However, there is already a race, and grabbing the name
+ * cache lock only makes the race window slightly smaller.
+ *
+ * The race happens because the vnode already exists in the name
+ * cache, and could be found by one thread before another thread
+ * can set the hard link flag.
+ */
+
+ vp->v_flag |= VISHARDLINK;
+
+ vnode_unlock(vp);
+}
+
+
+
+/*
+ * backwards compatibility
+ */
+void vnode_uncache_credentials(vnode_t vp)
+{
+ vnode_uncache_authorized_action(vp, KAUTH_INVALIDATE_CACHED_RIGHTS);
+}
+
+
+/*
+ * use the exclusive form of NAME_CACHE_LOCK to protect the update of the
+ * following fields in the vnode: v_cred_timestamp, v_cred, v_authorized_actions
+ * we use this lock so that we can look at the v_cred and v_authorized_actions
+ * atomically while behind the NAME_CACHE_LOCK in shared mode in 'cache_lookup_path',
+ * which is the super-hot path... if we are updating the authorized actions for this
+ * vnode, we are already in the super-slow and far less frequented path so its not
+ * that bad that we take the lock exclusive for this case... of course we strive
+ * to hold it for the minimum amount of time possible
+ */
+
+void vnode_uncache_authorized_action(vnode_t vp, kauth_action_t action)
+{
+ kauth_cred_t tcred = NOCRED;
+
+ NAME_CACHE_LOCK();
+
+ vp->v_authorized_actions &= ~action;
+
+ if (action == KAUTH_INVALIDATE_CACHED_RIGHTS &&
+ IS_VALID_CRED(vp->v_cred)) {
+ /*
+ * Use a temp variable to avoid kauth_cred_unref() while NAME_CACHE_LOCK is held
+ */
+ tcred = vp->v_cred;
+ vp->v_cred = NOCRED;
+ }
+ NAME_CACHE_UNLOCK();
+
+ if (tcred != NOCRED)
+ kauth_cred_unref(&tcred);
+}
+
+
+extern int bootarg_vnode_cache_defeat; /* default = 0, from bsd_init.c */
+
+boolean_t
+vnode_cache_is_authorized(vnode_t vp, vfs_context_t ctx, kauth_action_t action)
+{
+ kauth_cred_t ucred;
+ boolean_t retval = FALSE;
+
+ /* Boot argument to defeat rights caching */
+ if (bootarg_vnode_cache_defeat)
+ return FALSE;
+
+ if ( (vp->v_mount->mnt_kern_flag & (MNTK_AUTH_OPAQUE | MNTK_AUTH_CACHE_TTL)) ) {
+ /*
+ * a TTL is enabled on the rights cache... handle it here
+ * a TTL of 0 indicates that no rights should be cached
+ */
+ if (vp->v_mount->mnt_authcache_ttl) {
+ if ( !(vp->v_mount->mnt_kern_flag & MNTK_AUTH_CACHE_TTL) ) {
+ /*
+ * For filesystems marked only MNTK_AUTH_OPAQUE (generally network ones),
+ * we will only allow a SEARCH right on a directory to be cached...
+ * that cached right always has a default TTL associated with it
+ */
+ if (action != KAUTH_VNODE_SEARCH || vp->v_type != VDIR)
+ vp = NULLVP;
+ }
+ if (vp != NULLVP && vnode_cache_is_stale(vp) == TRUE) {
+ vnode_uncache_authorized_action(vp, vp->v_authorized_actions);
+ vp = NULLVP;
+ }
+ } else
+ vp = NULLVP;
+ }
+ if (vp != NULLVP) {
+ ucred = vfs_context_ucred(ctx);
+
+ NAME_CACHE_LOCK_SHARED();
+
+ if (vp->v_cred == ucred && (vp->v_authorized_actions & action) == action)
+ retval = TRUE;
+
+ NAME_CACHE_UNLOCK();
+ }
+ return retval;
+}
+
+
+void vnode_cache_authorized_action(vnode_t vp, vfs_context_t ctx, kauth_action_t action)
+{
+ kauth_cred_t tcred = NOCRED;
+ kauth_cred_t ucred;
+ struct timeval tv;
+ boolean_t ttl_active = FALSE;
+
+ ucred = vfs_context_ucred(ctx);
+
+ if (!IS_VALID_CRED(ucred) || action == 0)
+ return;
+
+ if ( (vp->v_mount->mnt_kern_flag & (MNTK_AUTH_OPAQUE | MNTK_AUTH_CACHE_TTL)) ) {
+ /*
+ * a TTL is enabled on the rights cache... handle it here
+ * a TTL of 0 indicates that no rights should be cached
+ */
+ if (vp->v_mount->mnt_authcache_ttl == 0)
+ return;
+
+ if ( !(vp->v_mount->mnt_kern_flag & MNTK_AUTH_CACHE_TTL) ) {
+ /*
+ * only cache SEARCH action for filesystems marked
+ * MNTK_AUTH_OPAQUE on VDIRs...
+ * the lookup_path code will time these out
+ */
+ if ( (action & ~KAUTH_VNODE_SEARCH) || vp->v_type != VDIR )
+ return;
+ }
+ ttl_active = TRUE;
+
+ microuptime(&tv);
+ }
+ NAME_CACHE_LOCK();
+
+ if (vp->v_cred != ucred) {
+ kauth_cred_ref(ucred);
+ /*
+ * Use a temp variable to avoid kauth_cred_unref() while NAME_CACHE_LOCK is held
+ */
+ tcred = vp->v_cred;
+ vp->v_cred = ucred;
+ vp->v_authorized_actions = 0;
+ }
+ if (ttl_active == TRUE && vp->v_authorized_actions == 0) {
+ /*
+ * only reset the timestamnp on the
+ * first authorization cached after the previous
+ * timer has expired or we're switching creds...
+ * 'vnode_cache_is_authorized' will clear the
+ * authorized actions if the TTL is active and
+ * it has expired
+ */
+ vp->v_cred_timestamp = tv.tv_sec;
+ }
+ vp->v_authorized_actions |= action;
+
+ NAME_CACHE_UNLOCK();
+
+ if (IS_VALID_CRED(tcred))
+ kauth_cred_unref(&tcred);
+}
+
+
+boolean_t vnode_cache_is_stale(vnode_t vp)
+{
+ struct timeval tv;
+ boolean_t retval;
+
+ microuptime(&tv);
+
+ if ((tv.tv_sec - vp->v_cred_timestamp) > vp->v_mount->mnt_authcache_ttl)
+ retval = TRUE;
+ else
+ retval = FALSE;
+
+ return retval;
+}
+
+
+
+/*
+ * Returns: 0 Success
+ * ERECYCLE vnode was recycled from underneath us. Force lookup to be re-driven from namei.
+ * This errno value should not be seen by anyone outside of the kernel.
+ */
+int
+cache_lookup_path(struct nameidata *ndp, struct componentname *cnp, vnode_t dp,
+ vfs_context_t ctx, int *dp_authorized, vnode_t last_dp)
+{
+ char *cp; /* pointer into pathname argument */
+ int vid;
+ int vvid = 0; /* protected by vp != NULLVP */
+ vnode_t vp = NULLVP;
+ vnode_t tdp = NULLVP;
+ kauth_cred_t ucred;
+ boolean_t ttl_enabled = FALSE;
+ struct timeval tv;
+ mount_t mp;
+ unsigned int hash;
+ int error = 0;
+ boolean_t dotdotchecked = FALSE;
+
+#if CONFIG_TRIGGERS
+ vnode_t trigger_vp;
+#endif /* CONFIG_TRIGGERS */
+
+ ucred = vfs_context_ucred(ctx);
+ ndp->ni_flag &= ~(NAMEI_TRAILINGSLASH);
+
+ NAME_CACHE_LOCK_SHARED();
+
+ if ( dp->v_mount && (dp->v_mount->mnt_kern_flag & (MNTK_AUTH_OPAQUE | MNTK_AUTH_CACHE_TTL)) ) {
+ ttl_enabled = TRUE;
+ microuptime(&tv);
+ }
+ for (;;) {
+ /*
+ * Search a directory.
+ *
+ * The cn_hash value is for use by cache_lookup
+ * The last component of the filename is left accessible via
+ * cnp->cn_nameptr for callers that need the name.
+ */
+ hash = 0;
+ cp = cnp->cn_nameptr;
+
+ while (*cp && (*cp != '/')) {
+ hash = crc32tab[((hash >> 24) ^ (unsigned char)*cp++)] ^ hash << 8;
+ }
+ /*
+ * the crc generator can legitimately generate
+ * a 0... however, 0 for us means that we
+ * haven't computed a hash, so use 1 instead
+ */
+ if (hash == 0)
+ hash = 1;
+ cnp->cn_hash = hash;
+ cnp->cn_namelen = cp - cnp->cn_nameptr;
+
+ ndp->ni_pathlen -= cnp->cn_namelen;
+ ndp->ni_next = cp;
+
+ /*
+ * Replace multiple slashes by a single slash and trailing slashes
+ * by a null. This must be done before VNOP_LOOKUP() because some
+ * fs's don't know about trailing slashes. Remember if there were
+ * trailing slashes to handle symlinks, existing non-directories
+ * and non-existing files that won't be directories specially later.
+ */
+ while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
+ cp++;
+ ndp->ni_pathlen--;
+
+ if (*cp == '\0') {
+ ndp->ni_flag |= NAMEI_TRAILINGSLASH;
+ *ndp->ni_next = '\0';
+ }
+ }
+ ndp->ni_next = cp;
+
+ cnp->cn_flags &= ~(MAKEENTRY | ISLASTCN | ISDOTDOT);
+
+ if (*cp == '\0')
+ cnp->cn_flags |= ISLASTCN;
+
+ if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
+ cnp->cn_flags |= ISDOTDOT;
+
+ *dp_authorized = 0;
+#if NAMEDRSRCFORK
+ /*
+ * Process a request for a file's resource fork.
+ *
+ * Consume the _PATH_RSRCFORKSPEC suffix and tag the path.
+ */
+ if ((ndp->ni_pathlen == sizeof(_PATH_RSRCFORKSPEC)) &&
+ (cp[1] == '.' && cp[2] == '.') &&
+ bcmp(cp, _PATH_RSRCFORKSPEC, sizeof(_PATH_RSRCFORKSPEC)) == 0) {
+ /* Skip volfs file systems that don't support native streams. */
+ if ((dp->v_mount != NULL) &&
+ (dp->v_mount->mnt_flag & MNT_DOVOLFS) &&
+ (dp->v_mount->mnt_kern_flag & MNTK_NAMED_STREAMS) == 0) {
+ goto skiprsrcfork;
+ }
+ cnp->cn_flags |= CN_WANTSRSRCFORK;
+ cnp->cn_flags |= ISLASTCN;
+ ndp->ni_next[0] = '\0';
+ ndp->ni_pathlen = 1;
+ }
+skiprsrcfork:
+#endif
+
+#if CONFIG_MACF
+
+ /*
+ * Name cache provides authorization caching (see below)
+ * that will short circuit MAC checks in lookup().
+ * We must perform MAC check here. On denial
+ * dp_authorized will remain 0 and second check will
+ * be perfomed in lookup().
+ */
+ if (!(cnp->cn_flags & DONOTAUTH)) {
+ error = mac_vnode_check_lookup(ctx, dp, cnp);
+ if (error) {
+ NAME_CACHE_UNLOCK();
+ goto errorout;
+ }
+ }
+#endif /* MAC */
+ if (ttl_enabled && ((tv.tv_sec - dp->v_cred_timestamp) > dp->v_mount->mnt_authcache_ttl))
+ break;
+
+ /*
+ * NAME_CACHE_LOCK holds these fields stable
+ *
+ * We can't cache KAUTH_VNODE_SEARCHBYANYONE for root correctly
+ * so we make an ugly check for root here. root is always
+ * allowed and breaking out of here only to find out that is
+ * authorized by virtue of being root is very very expensive.
+ */
+ if ((dp->v_cred != ucred || !(dp->v_authorized_actions & KAUTH_VNODE_SEARCH)) &&
+ !(dp->v_authorized_actions & KAUTH_VNODE_SEARCHBYANYONE) &&
+ !vfs_context_issuser(ctx))
+ break;
+
+ /*
+ * indicate that we're allowed to traverse this directory...
+ * even if we fail the cache lookup or decide to bail for
+ * some other reason, this information is valid and is used
+ * to avoid doing a vnode_authorize before the call to VNOP_LOOKUP
+ */
+ *dp_authorized = 1;
+
+ if ( (cnp->cn_flags & (ISLASTCN | ISDOTDOT)) ) {
+ if (cnp->cn_nameiop != LOOKUP)
+ break;
+ if (cnp->cn_flags & LOCKPARENT)
+ break;
+ if (cnp->cn_flags & NOCACHE)
+ break;
+ if (cnp->cn_flags & ISDOTDOT) {
+ /*
+ * Force directory hardlinks to go to
+ * file system for ".." requests.
+ */
+ if (dp && (dp->v_flag & VISHARDLINK)) {
+ break;
+ }
+ /*
+ * Quit here only if we can't use
+ * the parent directory pointer or
+ * don't have one. Otherwise, we'll
+ * use it below.
+ */
+ if ((dp->v_flag & VROOT) ||
+ dp == ndp->ni_rootdir ||
+ dp->v_parent == NULLVP)
+ break;
+ }
+ }
+
+ if ((cnp->cn_flags & CN_SKIPNAMECACHE)) {
+ /*
+ * Force lookup to go to the filesystem with
+ * all cnp fields set up.
+ */
+ break;
+ }
+
+ /*
+ * "." and ".." aren't supposed to be cached, so check
+ * for them before checking the cache.
+ */
+ if (cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.')
+ vp = dp;
+ else if ( (cnp->cn_flags & ISDOTDOT) ) {
+ /*
+ * If this is a chrooted process, we need to check if
+ * the process is trying to break out of its chrooted
+ * jail. We do that by trying to determine if dp is
+ * a subdirectory of ndp->ni_rootdir. If we aren't
+ * able to determine that by the v_parent pointers, we
+ * will leave the fast path.
+ *
+ * Since this function may see dotdot components
+ * many times and it has the name cache lock held for
+ * the entire duration, we optimise this by doing this
+ * check only once per cache_lookup_path call.
+ * If dotdotchecked is set, it means we've done this
+ * check once already and don't need to do it again.
+ */
+ if (!dotdotchecked && (ndp->ni_rootdir != rootvnode)) {
+ vnode_t tvp = dp;
+ boolean_t defer = FALSE;
+ boolean_t is_subdir = FALSE;
+
+ defer = cache_check_vnode_issubdir(tvp,
+ ndp->ni_rootdir, &is_subdir, &tvp);
+
+ if (defer) {
+ /* defer to Filesystem */
+ break;
+ } else if (!is_subdir) {
+ /*
+ * This process is trying to break out
+ * of its chrooted jail, so all its
+ * dotdot accesses will be translated to
+ * its root directory.
+ */
+ vp = ndp->ni_rootdir;
+ } else {
+ /*
+ * All good, let this dotdot access
+ * proceed normally
+ */
+ vp = dp->v_parent;
+ }
+ dotdotchecked = TRUE;
+ } else {
+ vp = dp->v_parent;
+ }
+ } else {
+ if ( (vp = cache_lookup_locked(dp, cnp)) == NULLVP)
+ break;
+
+ if ( (vp->v_flag & VISHARDLINK) ) {
+ /*
+ * The file system wants a VNOP_LOOKUP on this vnode
+ */
+ vp = NULL;
+ break;
+ }
+ }
+ if ( (cnp->cn_flags & ISLASTCN) )
+ break;
+
+ if (vp->v_type != VDIR) {
+ if (vp->v_type != VLNK)
+ vp = NULL;
+ break;
+ }
+
+ if ( (mp = vp->v_mountedhere) && ((cnp->cn_flags & NOCROSSMOUNT) == 0)) {
+ vnode_t tmp_vp = mp->mnt_realrootvp;
+ if (tmp_vp == NULLVP || mp->mnt_generation != mount_generation ||
+ mp->mnt_realrootvp_vid != tmp_vp->v_id)
+ break;
+ vp = tmp_vp;
+ }
+
+#if CONFIG_TRIGGERS
+ /*
+ * After traversing all mountpoints stacked here, if we have a
+ * trigger in hand, resolve it. Note that we don't need to
+ * leave the fast path if the mount has already happened.
+ */
+ if (vp->v_resolve)
+ break;
+#endif /* CONFIG_TRIGGERS */
+
+
+ dp = vp;
+ vp = NULLVP;
+
+ cnp->cn_nameptr = ndp->ni_next + 1;
+ ndp->ni_pathlen--;
+ while (*cnp->cn_nameptr == '/') {
+ cnp->cn_nameptr++;
+ ndp->ni_pathlen--;
+ }
+ }
+ if (vp != NULLVP)
+ vvid = vp->v_id;
+ vid = dp->v_id;
+
+ NAME_CACHE_UNLOCK();
+
+ if ((vp != NULLVP) && (vp->v_type != VLNK) &&
+ ((cnp->cn_flags & (ISLASTCN | LOCKPARENT | WANTPARENT | SAVESTART)) == ISLASTCN)) {
+ /*
+ * if we've got a child and it's the last component, and
+ * the lookup doesn't need to return the parent then we
+ * can skip grabbing an iocount on the parent, since all
+ * we're going to do with it is a vnode_put just before
+ * we return from 'lookup'. If it's a symbolic link,
+ * we need the parent in case the link happens to be
+ * a relative pathname.
+ */
+ tdp = dp;
+ dp = NULLVP;
+ } else {
+need_dp:
+ /*
+ * return the last directory we looked at
+ * with an io reference held. If it was the one passed
+ * in as a result of the last iteration of VNOP_LOOKUP,
+ * it should already hold an io ref. No need to increase ref.
+ */
+ if (last_dp != dp){
+
+ if (dp == ndp->ni_usedvp) {
+ /*
+ * if this vnode matches the one passed in via USEDVP
+ * than this context already holds an io_count... just
+ * use vnode_get to get an extra ref for lookup to play
+ * with... can't use the getwithvid variant here because
+ * it will block behind a vnode_drain which would result
+ * in a deadlock (since we already own an io_count that the
+ * vnode_drain is waiting on)... vnode_get grabs the io_count
+ * immediately w/o waiting... it always succeeds
+ */
+ vnode_get(dp);
+ } else if ((error = vnode_getwithvid_drainok(dp, vid))) {
+ /*
+ * failure indicates the vnode
+ * changed identity or is being
+ * TERMINATED... in either case
+ * punt this lookup.
+ *
+ * don't necessarily return ENOENT, though, because
+ * we really want to go back to disk and make sure it's
+ * there or not if someone else is changing this
+ * vnode. That being said, the one case where we do want
+ * to return ENOENT is when the vnode's mount point is
+ * in the process of unmounting and we might cause a deadlock
+ * in our attempt to take an iocount. An ENODEV error return
+ * is from vnode_get* is an indication this but we change that
+ * ENOENT for upper layers.
+ */
+ if (error == ENODEV) {
+ error = ENOENT;
+ } else {
+ error = ERECYCLE;
+ }
+ goto errorout;
+ }
+ }
+ }
+ if (vp != NULLVP) {
+ if ( (vnode_getwithvid_drainok(vp, vvid)) ) {
+ vp = NULLVP;
+
+ /*
+ * can't get reference on the vp we'd like
+ * to return... if we didn't grab a reference
+ * on the directory (due to fast path bypass),
+ * then we need to do it now... we can't return
+ * with both ni_dvp and ni_vp NULL, and no
+ * error condition
+ */
+ if (dp == NULLVP) {
+ dp = tdp;
+ goto need_dp;
+ }
+ }
+ }
+
+ ndp->ni_dvp = dp;
+ ndp->ni_vp = vp;
+
+#if CONFIG_TRIGGERS
+ trigger_vp = vp ? vp : dp;
+ if ((error == 0) && (trigger_vp != NULLVP) && vnode_isdir(trigger_vp)) {
+ error = vnode_trigger_resolve(trigger_vp, ndp, ctx);
+ if (error) {
+ if (vp)
+ vnode_put(vp);
+ if (dp)
+ vnode_put(dp);
+ goto errorout;
+ }
+ }
+#endif /* CONFIG_TRIGGERS */
+
+errorout:
+ /*
+ * If we came into cache_lookup_path after an iteration of the lookup loop that
+ * resulted in a call to VNOP_LOOKUP, then VNOP_LOOKUP returned a vnode with a io ref
+ * on it. It is now the job of cache_lookup_path to drop the ref on this vnode
+ * when it is no longer needed. If we get to this point, and last_dp is not NULL
+ * and it is ALSO not the dvp we want to return to caller of this function, it MUST be
+ * the case that we got to a subsequent path component and this previous vnode is
+ * no longer needed. We can then drop the io ref on it.
+ */
+ if ((last_dp != NULLVP) && (last_dp != ndp->ni_dvp)){
+ vnode_put(last_dp);
+ }
+
+ //initialized to 0, should be the same if no error cases occurred.
+ return error;
+}
+
+
+static vnode_t
+cache_lookup_locked(vnode_t dvp, struct componentname *cnp)
+{
+ struct namecache *ncp;
+ struct nchashhead *ncpp;
+ long namelen = cnp->cn_namelen;
+ unsigned int hashval = cnp->cn_hash;
+
+ if (nc_disabled) {
+ return NULL;
+ }
+
+ ncpp = NCHHASH(dvp, cnp->cn_hash);
+ LIST_FOREACH(ncp, ncpp, nc_hash) {
+ if ((ncp->nc_dvp == dvp) && (ncp->nc_hashval == hashval)) {
+ if (memcmp(ncp->nc_name, cnp->cn_nameptr, namelen) == 0 && ncp->nc_name[namelen] == 0)
+ break;
+ }
+ }
+ if (ncp == 0) {
+ /*
+ * We failed to find an entry
+ */
+ NCHSTAT(ncs_miss);
+ return (NULL);
+ }
+ NCHSTAT(ncs_goodhits);
+
+ return (ncp->nc_vp);
+}
+
+
+unsigned int hash_string(const char *cp, int len);
+//
+// Have to take a len argument because we may only need to
+// hash part of a componentname.
+//
+unsigned int
+hash_string(const char *cp, int len)
+{
+ unsigned hash = 0;
+
+ if (len) {
+ while (len--) {
+ hash = crc32tab[((hash >> 24) ^ (unsigned char)*cp++)] ^ hash << 8;
+ }
+ } else {
+ while (*cp != '\0') {
+ hash = crc32tab[((hash >> 24) ^ (unsigned char)*cp++)] ^ hash << 8;
+ }
+ }
+ /*
+ * the crc generator can legitimately generate
+ * a 0... however, 0 for us means that we
+ * haven't computed a hash, so use 1 instead
+ */
+ if (hash == 0)
+ hash = 1;
+ return hash;
+}
+
+
+/*
+ * Lookup an entry in the cache
+ *
+ * We don't do this if the segment name is long, simply so the cache
+ * can avoid holding long names (which would either waste space, or
+ * add greatly to the complexity).
+ *
+ * Lookup is called with dvp pointing to the directory to search,
+ * cnp pointing to the name of the entry being sought. If the lookup
+ * succeeds, the vnode is returned in *vpp, and a status of -1 is
+ * returned. If the lookup determines that the name does not exist
+ * (negative cacheing), a status of ENOENT is returned. If the lookup
+ * fails, a status of zero is returned.
+ */
+
+int
+cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
+{
+ struct namecache *ncp;
+ struct nchashhead *ncpp;
+ long namelen = cnp->cn_namelen;
+ unsigned int hashval;
+ boolean_t have_exclusive = FALSE;
+ uint32_t vid;
+ vnode_t vp;
+
+ if (cnp->cn_hash == 0)
+ cnp->cn_hash = hash_string(cnp->cn_nameptr, cnp->cn_namelen);
+ hashval = cnp->cn_hash;
+
+ if (nc_disabled) {
+ return 0;
+ }
+
+ NAME_CACHE_LOCK_SHARED();
+
+relook:
+ ncpp = NCHHASH(dvp, cnp->cn_hash);
+ LIST_FOREACH(ncp, ncpp, nc_hash) {
+ if ((ncp->nc_dvp == dvp) && (ncp->nc_hashval == hashval)) {
+ if (memcmp(ncp->nc_name, cnp->cn_nameptr, namelen) == 0 && ncp->nc_name[namelen] == 0)
+ break;
+ }
+ }
+ /* We failed to find an entry */
+ if (ncp == 0) {
+ NCHSTAT(ncs_miss);
+ NAME_CACHE_UNLOCK();
+ return (0);
+ }
+
+ /* We don't want to have an entry, so dump it */
+ if ((cnp->cn_flags & MAKEENTRY) == 0) {
+ if (have_exclusive == TRUE) {
+ NCHSTAT(ncs_badhits);
+ cache_delete(ncp, 1);
+ NAME_CACHE_UNLOCK();
+ return (0);
+ }
+ NAME_CACHE_UNLOCK();
+ NAME_CACHE_LOCK();
+ have_exclusive = TRUE;
+ goto relook;
+ }
+ vp = ncp->nc_vp;
+
+ /* We found a "positive" match, return the vnode */
+ if (vp) {
+ NCHSTAT(ncs_goodhits);
+
+ vid = vp->v_id;
+ NAME_CACHE_UNLOCK();
+
+ if (vnode_getwithvid(vp, vid)) {
+#if COLLECT_STATS
+ NAME_CACHE_LOCK();
+ NCHSTAT(ncs_badvid);
+ NAME_CACHE_UNLOCK();
+#endif
+ return (0);
+ }
+ *vpp = vp;
+ return (-1);
+ }
+
+ /* We found a negative match, and want to create it, so purge */
+ if (cnp->cn_nameiop == CREATE || cnp->cn_nameiop == RENAME) {
+ if (have_exclusive == TRUE) {
+ NCHSTAT(ncs_badhits);
+ cache_delete(ncp, 1);
+ NAME_CACHE_UNLOCK();
+ return (0);
+ }
+ NAME_CACHE_UNLOCK();
+ NAME_CACHE_LOCK();
+ have_exclusive = TRUE;
+ goto relook;
+ }
+
+ /*
+ * We found a "negative" match, ENOENT notifies client of this match.
+ */
+ NCHSTAT(ncs_neghits);
+
+ NAME_CACHE_UNLOCK();
+ return (ENOENT);
+}
+
+const char *
+cache_enter_create(vnode_t dvp, vnode_t vp, struct componentname *cnp)
+{
+ const char *strname;
+
+ if (cnp->cn_hash == 0)
+ cnp->cn_hash = hash_string(cnp->cn_nameptr, cnp->cn_namelen);
+
+ /*
+ * grab 2 references on the string entered
+ * one for the cache_enter_locked to consume
+ * and the second to be consumed by v_name (vnode_create call point)
+ */
+ strname = add_name_internal(cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_hash, TRUE, 0);
+
+ NAME_CACHE_LOCK();
+
+ cache_enter_locked(dvp, vp, cnp, strname);
+
+ NAME_CACHE_UNLOCK();
+
+ return (strname);
+}
+
+
+/*
+ * Add an entry to the cache...
+ * but first check to see if the directory
+ * that this entry is to be associated with has
+ * had any cache_purges applied since we took
+ * our identity snapshot... this check needs to
+ * be done behind the name cache lock
+ */
+void
+cache_enter_with_gen(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, int gen)
+{
+
+ if (cnp->cn_hash == 0)
+ cnp->cn_hash = hash_string(cnp->cn_nameptr, cnp->cn_namelen);
+
+ NAME_CACHE_LOCK();
+
+ if (dvp->v_nc_generation == gen)
+ (void)cache_enter_locked(dvp, vp, cnp, NULL);
+
+ NAME_CACHE_UNLOCK();
+}
+
+
+/*
+ * Add an entry to the cache.
+ */
+void
+cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp)
+{
+ const char *strname;
+
+ if (cnp->cn_hash == 0)
+ cnp->cn_hash = hash_string(cnp->cn_nameptr, cnp->cn_namelen);
+
+ /*
+ * grab 1 reference on the string entered
+ * for the cache_enter_locked to consume
+ */
+ strname = add_name_internal(cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_hash, FALSE, 0);
+
+ NAME_CACHE_LOCK();
+
+ cache_enter_locked(dvp, vp, cnp, strname);
+
+ NAME_CACHE_UNLOCK();
+}
+
+
+static void
+cache_enter_locked(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, const char *strname)
+{
+ struct namecache *ncp, *negp;
+ struct nchashhead *ncpp;
+
+ if (nc_disabled)
+ return;
+
+ /*
+ * if the entry is for -ve caching vp is null
+ */
+ if ((vp != NULLVP) && (LIST_FIRST(&vp->v_nclinks))) {
+ /*
+ * someone beat us to the punch..
+ * this vnode is already in the cache
+ */
+ if (strname != NULL)
+ vfs_removename(strname);
+ return;
+ }
+ /*
+ * We allocate a new entry if we are less than the maximum
+ * allowed and the one at the front of the list is in use.
+ * Otherwise we use the one at the front of the list.
+ */
+ if (numcache < desiredNodes &&
+ ((ncp = nchead.tqh_first) == NULL ||
+ ncp->nc_hash.le_prev != 0)) {
+ /*
+ * Allocate one more entry
+ */
+ ncp = (struct namecache *)_MALLOC_ZONE(sizeof(*ncp), M_CACHE, M_WAITOK);
+ numcache++;
+ } else {
+ /*
+ * reuse an old entry
+ */
+ ncp = TAILQ_FIRST(&nchead);
+ TAILQ_REMOVE(&nchead, ncp, nc_entry);
+
+ if (ncp->nc_hash.le_prev != 0) {
+ /*
+ * still in use... we need to
+ * delete it before re-using it
+ */
+ NCHSTAT(ncs_stolen);
+ cache_delete(ncp, 0);
+ }
+ }
+ NCHSTAT(ncs_enters);
+
+ /*
+ * Fill in cache info, if vp is NULL this is a "negative" cache entry.
+ */
+ ncp->nc_vp = vp;
+ ncp->nc_dvp = dvp;
+ ncp->nc_hashval = cnp->cn_hash;
+
+ if (strname == NULL)
+ ncp->nc_name = add_name_internal(cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_hash, FALSE, 0);
+ else
+ ncp->nc_name = strname;
+
+ //
+ // If the bytes of the name associated with the vnode differ,
+ // use the name associated with the vnode since the file system
+ // may have set that explicitly in the case of a lookup on a
+ // case-insensitive file system where the case of the looked up
+ // name differs from what is on disk. For more details, see:
+ // <rdar://problem/8044697> FSEvents doesn't always decompose diacritical unicode chars in the paths of the changed directories
+ //
+ const char *vn_name = vp ? vp->v_name : NULL;
+ unsigned int len = vn_name ? strlen(vn_name) : 0;
+ if (vn_name && ncp && ncp->nc_name && strncmp(ncp->nc_name, vn_name, len) != 0) {
+ unsigned int hash = hash_string(vn_name, len);
+
+ vfs_removename(ncp->nc_name);
+ ncp->nc_name = add_name_internal(vn_name, len, hash, FALSE, 0);
+ ncp->nc_hashval = hash;
+ }
+
+ /*
+ * make us the newest entry in the cache
+ * i.e. we'll be the last to be stolen
+ */
+ TAILQ_INSERT_TAIL(&nchead, ncp, nc_entry);
+
+ ncpp = NCHHASH(dvp, cnp->cn_hash);
+#if DIAGNOSTIC
+ {
+ struct namecache *p;
+
+ for (p = ncpp->lh_first; p != 0; p = p->nc_hash.le_next)
+ if (p == ncp)
+ panic("cache_enter: duplicate");
+ }
+#endif
+ /*
+ * make us available to be found via lookup
+ */
+ LIST_INSERT_HEAD(ncpp, ncp, nc_hash);
+
+ if (vp) {
+ /*
+ * add to the list of name cache entries
+ * that point at vp
+ */
+ LIST_INSERT_HEAD(&vp->v_nclinks, ncp, nc_un.nc_link);
+ } else {
+ /*
+ * this is a negative cache entry (vp == NULL)
+ * stick it on the negative cache list.
+ */
+ TAILQ_INSERT_TAIL(&neghead, ncp, nc_un.nc_negentry);
+
+ ncs_negtotal++;
+
+ if (ncs_negtotal > desiredNegNodes) {
+ /*
+ * if we've reached our desired limit
+ * of negative cache entries, delete
+ * the oldest
+ */
+ negp = TAILQ_FIRST(&neghead);
+ cache_delete(negp, 1);
+ }
+ }
+ /*
+ * add us to the list of name cache entries that
+ * are children of dvp
+ */
+ if (vp)
+ TAILQ_INSERT_TAIL(&dvp->v_ncchildren, ncp, nc_child);
+ else
+ TAILQ_INSERT_HEAD(&dvp->v_ncchildren, ncp, nc_child);
+}
+
+
+/*
+ * Initialize CRC-32 remainder table.
+ */
+static void init_crc32(void)
+{
+ /*
+ * the CRC-32 generator polynomial is:
+ * x^32 + x^26 + x^23 + x^22 + x^16 + x^12 + x^10
+ * + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1
+ */
+ unsigned int crc32_polynomial = 0x04c11db7;
+ unsigned int i,j;
+
+ /*
+ * pre-calculate the CRC-32 remainder for each possible octet encoding
+ */
+ for (i = 0; i < 256; i++) {
+ unsigned int crc_rem = i << 24;
+
+ for (j = 0; j < 8; j++) {
+ if (crc_rem & 0x80000000)
+ crc_rem = (crc_rem << 1) ^ crc32_polynomial;
+ else
+ crc_rem = (crc_rem << 1);
+ }
+ crc32tab[i] = crc_rem;
+ }
+}
+
+
+/*
+ * Name cache initialization, from vfs_init() when we are booting
+ */
+void
+nchinit(void)
+{
+ int i;
+
+ desiredNegNodes = (desiredvnodes / 10);
+ desiredNodes = desiredvnodes + desiredNegNodes;
+
+ TAILQ_INIT(&nchead);
+ TAILQ_INIT(&neghead);
+
+ init_crc32();
+
+ nchashtbl = hashinit(MAX(CONFIG_NC_HASH, (2 *desiredNodes)), M_CACHE, &nchash);
+ nchashmask = nchash;
+ nchash++;
+
+ init_string_table();
+
+ /* Allocate name cache lock group attribute and group */
+ namecache_lck_grp_attr= lck_grp_attr_alloc_init();
+
+ namecache_lck_grp = lck_grp_alloc_init("Name Cache", namecache_lck_grp_attr);
+
+ /* Allocate name cache lock attribute */
+ namecache_lck_attr = lck_attr_alloc_init();
+
+ /* Allocate name cache lock */
+ namecache_rw_lock = lck_rw_alloc_init(namecache_lck_grp, namecache_lck_attr);
+
+
+ /* Allocate string cache lock group attribute and group */
+ strcache_lck_grp_attr= lck_grp_attr_alloc_init();
+
+ strcache_lck_grp = lck_grp_alloc_init("String Cache", strcache_lck_grp_attr);
+
+ /* Allocate string cache lock attribute */
+ strcache_lck_attr = lck_attr_alloc_init();
+
+ /* Allocate string cache lock */
+ strtable_rw_lock = lck_rw_alloc_init(strcache_lck_grp, strcache_lck_attr);
+
+ for (i = 0; i < NUM_STRCACHE_LOCKS; i++)
+ lck_mtx_init(&strcache_mtx_locks[i], strcache_lck_grp, strcache_lck_attr);
+}
+
+void
+name_cache_lock_shared(void)
+{
+ lck_rw_lock_shared(namecache_rw_lock);
+}
+
+void
+name_cache_lock(void)
+{
+ lck_rw_lock_exclusive(namecache_rw_lock);
+}
+
+void
+name_cache_unlock(void)
+{
+ lck_rw_done(namecache_rw_lock);
+}
+
+
+int
+resize_namecache(u_int newsize)
+{
+ struct nchashhead *new_table;
+ struct nchashhead *old_table;
+ struct nchashhead *old_head, *head;
+ struct namecache *entry, *next;
+ uint32_t i, hashval;
+ int dNodes, dNegNodes;
+ u_long new_size, old_size;
+
+ dNegNodes = (newsize / 10);
+ dNodes = newsize + dNegNodes;
+
+ // we don't support shrinking yet
+ if (dNodes <= desiredNodes) {
+ return 0;
+ }
+ new_table = hashinit(2 * dNodes, M_CACHE, &nchashmask);
+ new_size = nchashmask + 1;
+
+ if (new_table == NULL) {
+ return ENOMEM;
+ }
+
+ NAME_CACHE_LOCK();
+ // do the switch!
+ old_table = nchashtbl;
+ nchashtbl = new_table;
+ old_size = nchash;
+ nchash = new_size;
+
+ // walk the old table and insert all the entries into
+ // the new table
+ //
+ for(i=0; i < old_size; i++) {
+ old_head = &old_table[i];
+ for (entry=old_head->lh_first; entry != NULL; entry=next) {
+ //
+ // XXXdbg - Beware: this assumes that hash_string() does
+ // the same thing as what happens in
+ // lookup() over in vfs_lookup.c
+ hashval = hash_string(entry->nc_name, 0);
+ entry->nc_hashval = hashval;
+ head = NCHHASH(entry->nc_dvp, hashval);
+
+ next = entry->nc_hash.le_next;
+ LIST_INSERT_HEAD(head, entry, nc_hash);
+ }
+ }
+ desiredNodes = dNodes;
+ desiredNegNodes = dNegNodes;
+
+ NAME_CACHE_UNLOCK();
+ FREE(old_table, M_CACHE);
+
+ return 0;
+}
+
+static void
+cache_delete(struct namecache *ncp, int age_entry)
+{
+ NCHSTAT(ncs_deletes);
+
+ if (ncp->nc_vp) {
+ LIST_REMOVE(ncp, nc_un.nc_link);
+ } else {
+ TAILQ_REMOVE(&neghead, ncp, nc_un.nc_negentry);
+ ncs_negtotal--;
+ }
+ TAILQ_REMOVE(&(ncp->nc_dvp->v_ncchildren), ncp, nc_child);
+
+ LIST_REMOVE(ncp, nc_hash);
+ /*
+ * this field is used to indicate
+ * that the entry is in use and
+ * must be deleted before it can
+ * be reused...
+ */
+ ncp->nc_hash.le_prev = NULL;
+
+ if (age_entry) {
+ /*
+ * make it the next one available
+ * for cache_enter's use
+ */
+ TAILQ_REMOVE(&nchead, ncp, nc_entry);
+ TAILQ_INSERT_HEAD(&nchead, ncp, nc_entry);
+ }
+ vfs_removename(ncp->nc_name);
+ ncp->nc_name = NULL;
+}
+
+
+/*
+ * purge the entry associated with the
+ * specified vnode from the name cache
+ */
+void
+cache_purge(vnode_t vp)
+{
+ struct namecache *ncp;
+ kauth_cred_t tcred = NULL;
+
+ if ((LIST_FIRST(&vp->v_nclinks) == NULL) &&
+ (TAILQ_FIRST(&vp->v_ncchildren) == NULL) &&
+ (vp->v_cred == NOCRED) &&
+ (vp->v_parent == NULLVP))
+ return;
+
+ NAME_CACHE_LOCK();
+
+ if (vp->v_parent)
+ vp->v_parent->v_nc_generation++;
+
+ while ( (ncp = LIST_FIRST(&vp->v_nclinks)) )
+ cache_delete(ncp, 1);
+
+ while ( (ncp = TAILQ_FIRST(&vp->v_ncchildren)) )
+ cache_delete(ncp, 1);
+
+ /*
+ * Use a temp variable to avoid kauth_cred_unref() while NAME_CACHE_LOCK is held
+ */
+ tcred = vp->v_cred;
+ vp->v_cred = NOCRED;
+ vp->v_authorized_actions = 0;
+
+ NAME_CACHE_UNLOCK();
+
+ if (IS_VALID_CRED(tcred))
+ kauth_cred_unref(&tcred);
+}
+
+/*
+ * Purge all negative cache entries that are children of the
+ * given vnode. A case-insensitive file system (or any file
+ * system that has multiple equivalent names for the same
+ * directory entry) can use this when creating or renaming
+ * to remove negative entries that may no longer apply.
+ */
+void
+cache_purge_negatives(vnode_t vp)
+{
+ struct namecache *ncp, *next_ncp;
+
+ NAME_CACHE_LOCK();
+
+ TAILQ_FOREACH_SAFE(ncp, &vp->v_ncchildren, nc_child, next_ncp) {
+ if (ncp->nc_vp)
+ break;
+
+ cache_delete(ncp, 1);
+ }
+
+ NAME_CACHE_UNLOCK();
+}
+
+/*
+ * Flush all entries referencing a particular filesystem.
+ *
+ * Since we need to check it anyway, we will flush all the invalid
+ * entries at the same time.
+ */
+void
+cache_purgevfs(struct mount *mp)
+{
+ struct nchashhead *ncpp;
+ struct namecache *ncp;
+
+ NAME_CACHE_LOCK();
+ /* Scan hash tables for applicable entries */
+ for (ncpp = &nchashtbl[nchash - 1]; ncpp >= nchashtbl; ncpp--) {
+restart:
+ for (ncp = ncpp->lh_first; ncp != 0; ncp = ncp->nc_hash.le_next) {
+ if (ncp->nc_dvp->v_mount == mp) {
+ cache_delete(ncp, 0);
+ goto restart;
+ }
+ }
+ }
+ NAME_CACHE_UNLOCK();
+}
+
+
+
+//
+// String ref routines
+//
+static LIST_HEAD(stringhead, string_t) *string_ref_table;
+static u_long string_table_mask;
+static uint32_t filled_buckets=0;
+
+
+typedef struct string_t {
+ LIST_ENTRY(string_t) hash_chain;
+ const char *str;
+ uint32_t refcount;
+} string_t;
+
+
+static void
+resize_string_ref_table(void)
+{
+ struct stringhead *new_table;
+ struct stringhead *old_table;
+ struct stringhead *old_head, *head;
+ string_t *entry, *next;
+ uint32_t i, hashval;
+ u_long new_mask, old_mask;
+
+ /*
+ * need to hold the table lock exclusively
+ * in order to grow the table... need to recheck
+ * the need to resize again after we've taken
+ * the lock exclusively in case some other thread
+ * beat us to the punch
+ */
+ lck_rw_lock_exclusive(strtable_rw_lock);
+
+ if (4 * filled_buckets < ((string_table_mask + 1) * 3)) {
+ lck_rw_done(strtable_rw_lock);
+ return;
+ }
+ new_table = hashinit((string_table_mask + 1) * 2, M_CACHE, &new_mask);
+
+ if (new_table == NULL) {
+ printf("failed to resize the hash table.\n");
+ lck_rw_done(strtable_rw_lock);
+ return;
+ }
+
+ // do the switch!
+ old_table = string_ref_table;
+ string_ref_table = new_table;
+ old_mask = string_table_mask;
+ string_table_mask = new_mask;
+ filled_buckets = 0;
+
+ // walk the old table and insert all the entries into
+ // the new table
+ //
+ for (i = 0; i <= old_mask; i++) {
+ old_head = &old_table[i];
+ for (entry = old_head->lh_first; entry != NULL; entry = next) {
+ hashval = hash_string((const char *)entry->str, 0);
+ head = &string_ref_table[hashval & string_table_mask];
+ if (head->lh_first == NULL) {
+ filled_buckets++;
+ }
+ next = entry->hash_chain.le_next;
+ LIST_INSERT_HEAD(head, entry, hash_chain);
+ }
+ }
+ lck_rw_done(strtable_rw_lock);
+
+ FREE(old_table, M_CACHE);
+}
+
+
+static void
+init_string_table(void)
+{
+ string_ref_table = hashinit(CONFIG_VFS_NAMES, M_CACHE, &string_table_mask);
+}
+
+
+const char *
+vfs_addname(const char *name, uint32_t len, u_int hashval, u_int flags)
+{
+ return (add_name_internal(name, len, hashval, FALSE, flags));
+}
+
+
+static const char *
+add_name_internal(const char *name, uint32_t len, u_int hashval, boolean_t need_extra_ref, __unused u_int flags)
+{
+ struct stringhead *head;
+ string_t *entry;
+ uint32_t chain_len = 0;
+ uint32_t hash_index;
+ uint32_t lock_index;
+ char *ptr;
+
+ if (len > MAXPATHLEN)
+ len = MAXPATHLEN;
+
+ /*
+ * if the length already accounts for the null-byte, then
+ * subtract one so later on we don't index past the end
+ * of the string.
+ */
+ if (len > 0 && name[len-1] == '\0') {
+ len--;
+ }
+ if (hashval == 0) {
+ hashval = hash_string(name, len);
+ }
+
+ /*
+ * take this lock 'shared' to keep the hash stable
+ * if someone else decides to grow the pool they
+ * will take this lock exclusively
+ */
+ lck_rw_lock_shared(strtable_rw_lock);
+
+ /*
+ * If the table gets more than 3/4 full, resize it
+ */
+ if (4 * filled_buckets >= ((string_table_mask + 1) * 3)) {
+ lck_rw_done(strtable_rw_lock);
+
+ resize_string_ref_table();
+
+ lck_rw_lock_shared(strtable_rw_lock);
+ }
+ hash_index = hashval & string_table_mask;
+ lock_index = hash_index % NUM_STRCACHE_LOCKS;
+
+ head = &string_ref_table[hash_index];
+
+ lck_mtx_lock_spin(&strcache_mtx_locks[lock_index]);
+
+ for (entry = head->lh_first; entry != NULL; chain_len++, entry = entry->hash_chain.le_next) {
+ if (memcmp(entry->str, name, len) == 0 && entry->str[len] == 0) {
+ entry->refcount++;
+ break;
+ }
+ }
+ if (entry == NULL) {
+ lck_mtx_convert_spin(&strcache_mtx_locks[lock_index]);
+ /*
+ * it wasn't already there so add it.
+ */
+ MALLOC(entry, string_t *, sizeof(string_t) + len + 1, M_TEMP, M_WAITOK);
+
+ if (head->lh_first == NULL) {
+ OSAddAtomic(1, &filled_buckets);
+ }
+ ptr = (char *)((char *)entry + sizeof(string_t));
+ strncpy(ptr, name, len);
+ ptr[len] = '\0';
+ entry->str = ptr;
+ entry->refcount = 1;
+ LIST_INSERT_HEAD(head, entry, hash_chain);
+ }
+ if (need_extra_ref == TRUE)
+ entry->refcount++;
+
+ lck_mtx_unlock(&strcache_mtx_locks[lock_index]);
+ lck_rw_done(strtable_rw_lock);
+
+ return (const char *)entry->str;
+}
+
+
+int
+vfs_removename(const char *nameref)
+{
+ struct stringhead *head;
+ string_t *entry;
+ uint32_t hashval;
+ uint32_t hash_index;
+ uint32_t lock_index;
+ int retval = ENOENT;
+
+ hashval = hash_string(nameref, 0);
+
+ /*
+ * take this lock 'shared' to keep the hash stable
+ * if someone else decides to grow the pool they
+ * will take this lock exclusively
+ */
+ lck_rw_lock_shared(strtable_rw_lock);
+ /*
+ * must compute the head behind the table lock
+ * since the size and location of the table
+ * can change on the fly
+ */
+ hash_index = hashval & string_table_mask;
+ lock_index = hash_index % NUM_STRCACHE_LOCKS;
+
+ head = &string_ref_table[hash_index];
+
+ lck_mtx_lock_spin(&strcache_mtx_locks[lock_index]);
+
+ for (entry = head->lh_first; entry != NULL; entry = entry->hash_chain.le_next) {
+ if (entry->str == nameref) {
+ entry->refcount--;
+
+ if (entry->refcount == 0) {
+ LIST_REMOVE(entry, hash_chain);
+
+ if (head->lh_first == NULL) {
+ OSAddAtomic(-1, &filled_buckets);
+ }
+ } else {
+ entry = NULL;
+ }
+ retval = 0;
+ break;
+ }
+ }
+ lck_mtx_unlock(&strcache_mtx_locks[lock_index]);
+ lck_rw_done(strtable_rw_lock);
+
+ if (entry != NULL)
+ FREE(entry, M_TEMP);
+
+ return retval;
+}
+
+
+#ifdef DUMP_STRING_TABLE
+void
+dump_string_table(void)
+{
+ struct stringhead *head;
+ string_t *entry;
+ u_long i;
+
+ lck_rw_lock_shared(strtable_rw_lock);
+
+ for (i = 0; i <= string_table_mask; i++) {
+ head = &string_ref_table[i];
+ for (entry=head->lh_first; entry != NULL; entry=entry->hash_chain.le_next) {
+ printf("%6d - %s\n", entry->refcount, entry->str);
}
+ }
+ lck_rw_done(strtable_rw_lock);
}
+#endif /* DUMP_STRING_TABLE */
projects / apple / xnu.git / blobdiff