The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/sys/namei.h

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    1 /*      $OpenBSD: namei.h,v 1.50 2022/01/11 23:59:55 jsg Exp $  */
    2 /*      $NetBSD: namei.h,v 1.11 1996/02/09 18:25:20 christos Exp $      */
    3 
    4 /*
    5  * Copyright (c) 1985, 1989, 1991, 1993
    6  *      The Regents of the University of California.  All rights reserved.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 3. Neither the name of the University nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  *
   32  *      @(#)namei.h     8.4 (Berkeley) 8/20/94
   33  */
   34 
   35 #ifndef _SYS_NAMEI_H_
   36 #define _SYS_NAMEI_H_
   37 
   38 #include <sys/queue.h>
   39 #include <sys/tree.h>
   40 #include <sys/uio.h>
   41 
   42 struct unveil;
   43 
   44 /*
   45  * Encapsulation of namei parameters.
   46  */
   47 struct nameidata {
   48         /*
   49          * Arguments to namei/lookup.
   50          */
   51         const char *ni_dirp;            /* pathname pointer */
   52         int     ni_dirfd;               /* dirfd from *at() functions */
   53         enum    uio_seg ni_segflg;      /* location of pathname */
   54      /* u_long  ni_nameiop;                namei operation */
   55      /* u_long  ni_flags;                  flags to namei */
   56      /* struct  proc *ni_proc;             process requesting lookup */
   57         /*
   58          * Arguments to lookup.
   59          */
   60      /* struct  ucred *ni_cred;            credentials */
   61         struct  vnode *ni_startdir;     /* starting directory */
   62         struct  vnode *ni_rootdir;      /* logical root directory */
   63         uint64_t ni_pledge;             /* expected pledge for namei */
   64         u_char ni_unveil;               /* required unveil flags for namei */
   65         /*
   66          * Results: returned from/manipulated by lookup
   67          */
   68         struct  vnode *ni_vp;           /* vnode of result */
   69         struct  vnode *ni_dvp;          /* vnode of intermediate directory */
   70 
   71         /*
   72          * Shared between namei and lookup/commit routines.
   73          */
   74         size_t  ni_pathlen;             /* remaining chars in path */
   75         char    *ni_next;               /* next location in pathname */
   76         u_long  ni_loopcnt;             /* count of symlinks encountered */
   77         struct unveil *ni_unveil_match; /* last matching unveil component */
   78 
   79         /*
   80          * Lookup parameters: this structure describes the subset of
   81          * information from the nameidata structure that is passed
   82          * through the VOP interface.
   83          */
   84         struct componentname {
   85                 /*
   86                  * Arguments to lookup.
   87                  */
   88                 u_long  cn_nameiop;     /* namei operation */
   89                 u_long  cn_flags;       /* flags to namei */
   90                 struct  proc *cn_proc;  /* process requesting lookup */
   91                 struct  ucred *cn_cred; /* credentials */
   92                 /*
   93                  * Shared between lookup and commit routines.
   94                  */
   95                 char    *cn_pnbuf;      /* pathname buffer */
   96                 char    *cn_rpbuf;      /* realpath buffer */
   97                 size_t  cn_rpi;         /* realpath index */
   98                 char    *cn_nameptr;    /* pointer to looked up name */
   99                 long    cn_namelen;     /* length of looked up component */
  100                 long    cn_consume;     /* chars to consume in lookup() */
  101         } ni_cnd;
  102 };
  103 
  104 #ifdef _KERNEL
  105 /*
  106  * namei operations
  107  */
  108 #define LOOKUP          0       /* perform name lookup only */
  109 #define CREATE          1       /* setup for file creation */
  110 #define DELETE          2       /* setup for file deletion */
  111 #define RENAME          3       /* setup for file renaming */
  112 #define OPMASK          3       /* mask for operation */
  113 /*
  114  * namei operational modifier flags, stored in ni_cnd.flags
  115  */
  116 #define LOCKLEAF        0x0004  /* lock inode on return */
  117 #define LOCKPARENT      0x0008  /* want parent vnode returned locked */
  118 #define WANTPARENT      0x0010  /* want parent vnode returned unlocked */
  119 #define NOCACHE         0x0020  /* name must not be left in cache */
  120 #define FOLLOW          0x0040  /* follow symbolic links */
  121 #define NOFOLLOW        0x0000  /* do not follow symbolic links (pseudo) */
  122 #define MODMASK         0x00fc  /* mask of operational modifiers */
  123 /*
  124  * Namei parameter descriptors.
  125  *
  126  * SAVENAME may be set by either the callers of namei or by VOP_LOOKUP.
  127  * If the caller of namei sets the flag (for example execve wants to
  128  * know the name of the program that is being executed), then it must
  129  * free the buffer. If VOP_LOOKUP sets the flag, then the buffer must
  130  * be freed by either the commit routine or the VOP_ABORT routine.
  131  * SAVESTART is set only by the callers of namei. It implies SAVENAME
  132  * plus the addition of saving the parent directory that contains the
  133  * name in ni_startdir. It allows repeated calls to lookup for the
  134  * name being sought. The caller is responsible for releasing the
  135  * buffer and for vrele'ing ni_startdir.
  136  */
  137 #define NOCROSSMOUNT    0x000100      /* do not cross mount points */
  138 #define RDONLY          0x000200      /* lookup with read-only semantics */
  139 #define HASBUF          0x000400      /* has allocated pathname buffer */
  140 #define SAVENAME        0x000800      /* save pathname buffer */
  141 #define SAVESTART       0x001000      /* save starting directory */
  142 #define ISDOTDOT        0x002000      /* current component name is .. */
  143 #define MAKEENTRY       0x004000      /* entry is to be added to name cache */
  144 #define ISLASTCN        0x008000      /* this is last component of pathname */
  145 #define ISSYMLINK       0x010000      /* symlink needs interpretation */
  146 #define REALPATH        0x020000      /* save pathname buffer for realpath */
  147 #define REQUIREDIR      0x080000      /* must be a directory */
  148 #define STRIPSLASHES    0x100000      /* strip trailing slashes */
  149 #define PDIRUNLOCK      0x200000      /* vfs_lookup() unlocked parent dir */
  150 #define BYPASSUNVEIL    0x400000      /* bypass pledgepath check */
  151 #define KERNELPATH      0x800000      /* access file as kernel, not process */
  152 
  153 /*
  154  * Initialization of an nameidata structure.
  155  */
  156 void ndinitat(struct nameidata *ndp, u_long op, u_long flags,
  157     enum uio_seg segflg, int dirfd, const char *namep, struct proc *p);
  158 
  159 #define NDINITAT(ndp, op, flags, segflg, dirfd, namep, p)  \
  160         ndinitat(ndp, op, flags, segflg, dirfd, namep, p)
  161 
  162 #define NDINIT(ndp, op, flags, segflp, namep, p) \
  163         ndinitat(ndp, op, flags, segflp, AT_FDCWD, namep, p)
  164 
  165 /* Defined for users of NDINIT(). */
  166 #define AT_FDCWD        -100
  167 #endif
  168 
  169 /*
  170  * This structure describes the elements in the cache of recent
  171  * names looked up by namei.
  172  */
  173 
  174 #define NAMECACHE_MAXLEN 31 /* maximum name segment length we bother with */
  175 
  176 struct  namecache {
  177         TAILQ_ENTRY(namecache) nc_lru;  /* Regular Entry LRU chain */
  178         TAILQ_ENTRY(namecache) nc_neg;  /* Negative Entry LRU chain */
  179         RBT_ENTRY(namecache) n_rbcache; /* Namecache rb tree from vnode */
  180         TAILQ_ENTRY(namecache) nc_me;   /* ncp's referring to me */
  181         struct  vnode *nc_dvp;          /* vnode of parent of name */
  182         u_long  nc_dvpid;               /* capability number of nc_dvp */
  183         struct  vnode *nc_vp;           /* vnode the name refers to */
  184         u_long  nc_vpid;                /* capability number of nc_vp */
  185         char    nc_nlen;                /* length of name */
  186         char    nc_name[NAMECACHE_MAXLEN];      /* segment name */
  187 };
  188 
  189 #ifdef _KERNEL
  190 struct  namecache_rb_cache;
  191 
  192 int     namei(struct nameidata *ndp);
  193 int     vfs_lookup(struct nameidata *ndp);
  194 int     vfs_relookup(struct vnode *dvp, struct vnode **vpp,
  195                       struct componentname *cnp);
  196 void cache_tree_init(struct namecache_rb_cache *);
  197 void cache_purge(struct vnode *);
  198 int cache_lookup(struct vnode *, struct vnode **, struct componentname *);
  199 void cache_enter(struct vnode *, struct vnode *, struct componentname *);
  200 int cache_revlookup(struct vnode *, struct vnode **, char **, char *);
  201 void nchinit(void);
  202 struct mount;
  203 void cache_purgevfs(struct mount *);
  204 
  205 int unveil_add(struct proc *, struct nameidata *, const char *);
  206 void unveil_removevnode(struct vnode *);
  207 ssize_t unveil_find_cover(struct vnode *, struct proc *);
  208 struct unveil *unveil_lookup(struct vnode *, struct process *, ssize_t *);
  209 void unveil_start_relative(struct proc *, struct nameidata *, struct vnode *);
  210 void unveil_check_component(struct proc *, struct nameidata *, struct vnode *);
  211 int unveil_check_final(struct proc *, struct nameidata *);
  212 
  213 extern struct pool namei_pool;
  214 
  215 #endif
  216 
  217 /*
  218  * Stats on usefulness of namei caches.
  219  */
  220 struct  nchstats {
  221         u_int64_t       ncs_goodhits;   /* hits that we can really use */
  222         u_int64_t       ncs_neghits;    /* negative hits that we can use */
  223         u_int64_t       ncs_badhits;    /* hits we must drop */
  224         u_int64_t       ncs_falsehits;  /* hits with id mismatch */
  225         u_int64_t       ncs_miss;       /* misses */
  226         u_int64_t       ncs_long;       /* long names that ignore cache */
  227         u_int64_t       ncs_pass2;      /* names found with passes == 2 */
  228         u_int64_t       ncs_2passes;    /* number of times we attempt it */
  229         u_int64_t       ncs_revhits;    /* reverse-cache hits */
  230         u_int64_t       ncs_revmiss;    /* reverse-cache misses */
  231         u_int64_t       ncs_dothits;    /* hits on '.' lookups */
  232         u_int64_t       ncs_dotdothits; /* hits on '..' lookups */
  233 };
  234 
  235 /* These sysctl names are only really used by sysctl(8) */
  236 #define KERN_NCHSTATS_GOODHITS          1
  237 #define KERN_NCHSTATS_NEGHITS           2
  238 #define KERN_NCHSTATS_BADHITS           3
  239 #define KERN_NCHSTATS_FALSEHITS         4
  240 #define KERN_NCHSTATS_MISS              5
  241 #define KERN_NCHSTATS_LONG              6
  242 #define KERN_NCHSTATS_PASS2             7
  243 #define KERN_NCHSTATS_2PASSES           8
  244 #define KERN_NCHSTATS_REVHITS           9
  245 #define KERN_NCHSTATS_REVMISS           10
  246 #define KERN_NCHSTATS_DOTHITS           11
  247 #define KERN_NCHSTATS_DOTDOTHITS        12
  248 #define KERN_NCHSTATS_MAXID             13
  249 
  250 #define CTL_KERN_NCHSTATS_NAMES {               \
  251         { 0, 0 },                               \
  252         { "good_hits", CTLTYPE_QUAD },          \
  253         { "negative_hits", CTLTYPE_QUAD },      \
  254         { "bad_hits", CTLTYPE_QUAD },           \
  255         { "false_hits", CTLTYPE_QUAD },         \
  256         { "misses", CTLTYPE_QUAD },             \
  257         { "long_names", CTLTYPE_QUAD },         \
  258         { "pass2", CTLTYPE_QUAD },              \
  259         { "2passes", CTLTYPE_QUAD },            \
  260         { "ncs_revhits", CTLTYPE_QUAD },        \
  261         { "ncs_revmiss", CTLTYPE_QUAD },        \
  262         { "ncs_dothits", CTLTYPE_QUAD },        \
  263         { "nch_dotdothits", CTLTYPE_QUAD },     \
  264 }
  265 
  266 /* Unveil flags for namei */
  267 #define UNVEIL_READ     0x01
  268 #define UNVEIL_WRITE    0x02
  269 #define UNVEIL_CREATE   0x04
  270 #define UNVEIL_EXEC     0x08
  271 #define UNVEIL_USERSET  0x10
  272 #define UNVEIL_MASK     0x0F
  273 
  274 #endif /* !_SYS_NAMEI_H_ */

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