githubmirror/lsof

lib/rnmh.c
716 строк21 KB
Chen
Library part5 (#290)
24 май 2023, 13:55
24 май 2023, 13:55cab786c
/*
 * rnmh.c -- functions to read BSD format name cache information from a
 *	     kernel hash table
 */

/*
 * Copyright 1997 Purdue Research Foundation, West Lafayette, Indiana
 * 47907.  All rights reserved.
 *
 * Written by Victor A. Abell
 *
 * This software is not subject to any license of the American Telephone
 * and Telegraph Company or the Regents of the University of California.
 *
 * Permission is granted to anyone to use this software for any purpose on
 * any computer system, and to alter it and redistribute it freely, subject
 * to the following restrictions:
 *
 * 1. Neither the authors nor Purdue University are responsible for any
 *    consequences of the use of this software.
 *
 * 2. The origin of this software must not be misrepresented, either by
 *    explicit claim or by omission.  Credit to the authors and Purdue
 *    University must appear in documentation and sources.
 *
 * 3. Altered versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.
 *
 * 4. This notice may not be removed or altered.
 */

#include "common.h"
#include "machine.h"

#if defined(HASNCACHE) && defined(USE_LIB_RNMH)

/*
 * rnmh.c - read BSD format hashed kernel name cache
 */

/*
 * The caller must:
 *
 *	#include the relevant header file -- e.g., <sys/namei.h>.
 *
 *	Define X_NCACHE as the nickname for the kernel cache hash tables
 *	address.
 *
 *	Define X_NCSIZE as the nickname for the size of the kernel cache has
 *	table length.
 *
 *	Define NCACHE_NO_ROOT if the calling dialect doesn't support
 *	the locating of the root node of a file system.
 *
 *	Define the name of the name cache structure -- e.g.,
 *
 *		#define NCACHE	<structure name>
 *
 *
 *	Define the following casts, if they differ from the defaults:
 *
 *		NCACHE_SZ_CAST	case for X_NCSIZE (default unsigned long)
 *
 *	Define the names of these elements of struct NCACHE:
 *
 *		#define NCACHE_NM	<name>
 *		#define NCACHE_NXT	<link to next entry>
 *		#define NCACHE_NODEADDR	<node address>
 *		#define NCACHE_PARADDR	<parent node address>
 *
 *	Optionally define:
 *
 *		#define NCACHE_NMLEN	<name length>
 *
 *	Optionally define *both*:
 *
 *		#define	NCACHE_NODEID	<node capability ID>
 *		#define	NCACHE_PARID	<parent node capability ID>
 *
 * The caller may need to:
 *
 *	Define this prototype for ncache_load():
 *
 *		_PROTOTYPE(static void ncache_load,(void));
 *
 *	Define NCACHE_VROOT to be the value of the flag that signifies that
 *	the vnode is the root of its file system.
 *
 *		E.g., for BSDI >= 5:
 *
 *			#define NCACHE_VROOT	VV_ROOT
 *
 *	If not defined, NCACHE_VROOT is defined as "VROOT".
 *
 *	Define VNODE_VFLAG if the vnode's flag member's name isn't v_flag.
 *
 * Note: if NCHNAMLEN is defined, the name is assumed to be in
 * NCACHE_NM[NCHNAMLEN]; if it isn't defined, the name is assumed to be in an
 * extension that begins at NCACHE_NM[0].
 *
 * Note: if NCACHE_NMLEN is not defined, then NCACHE_NM must be a pointer to
 * a kernel allocated, NUL-terminated, string buffer.
 */

/*
 * Casts
 */

#    if !defined(NCACHE_NC_CAST)
#        define NCACHE_SZ_CAST unsigned long
#    endif /* !defined(NCACHE_NC_CAST) */

/*
 * Flags
 */

#    if !defined(NCACHE_NMLEN)
#        undef NCHNAMLEN
#    endif /* !defined(NCACHE_NMLEN) */

#    if !defined(NCACHE_VROOT)
#        define NCACHE_VROOT VROOT /* vnode is root of its file system */
#    endif                         /* !defined(NCACHE_VROOT) */

#    if !defined(VNODE_VFLAG)
#        define VNODE_VFLAG v_flag
#    endif /* !defined(VNODE_VFLAG) */

/*
 * Local static values
 */

static int Mch; /* name cache hash mask */

struct l_nch {
    KA_T na;            /* node address */
    KA_T pa;            /* parent node address */
    struct l_nch *pla;  /* parent local node address */
    int nl;             /* name length */
    struct l_nch *next; /* next entry */

#    if defined(NCACHE_NODEID)
    unsigned long id;  /* capability ID */
    unsigned long did; /* parent capability ID */
#    endif             /* defined(NCACHE_NODEID) */

#    if defined(NCHNAMLEN)
    char nm[NCHNAMLEN + 1]; /* name */
#    else                   /* !defined(NCHNAMLEN) */
    char nm[1]; /* variable length name */
#    endif                  /* defined(NCHNAMLEN) */
};

static struct l_nch *Ncache = (struct l_nch *)NULL;
/* the head of the local name cache */
static struct l_nch **Nchash = (struct l_nch **)NULL;
/* Ncache hash pointers */

#    if defined(NCACHE_NODEID)
#        define ncachehash(i, n)                                               \
            Nchash + (((((int)(n) >> 2) + ((int)(i))) * 31415) & Mch)
static struct l_nch *ncache_addr(unsigned long i, KA_T na);
#    else /* !defined(NCACHE_NODEID) */
#        define ncachehash(n) Nchash + ((((int)(n) >> 2) * 31415) & Mch)
static struct l_nch *ncache_addr(KA_T na);
#    endif /* defined(NCACHE_NODEID) */

#    if !defined(NCACHE_NO_ROOT)
static int ncache_isroot(struct lsof_context *ctx, KA_T na, char *cp);
#    endif /* !defined(NCACHE_NO_ROOT) */

/*
 * ncache_addr() - look up a node's local ncache address
 */

static struct l_nch *

#    if defined(NCACHE_NODEID)
ncache_addr(unsigned long i, /* node's capability ID */
#    else                    /* !defined(NCACHE_NODEID) */
ncache_addr(
#    endif                   /* defined(NCACHE_NODEID) */
            KA_T na)         /* node's address */
{
    struct l_nch **hp;

#    if defined(NCACHE_NODEID)
    for (hp = ncachehash(i, na); *hp; hp++)
#    else  /* !defined(NCACHE_NODEID) */
    for (hp = ncachehash(na); *hp; hp++)
#    endif /* defined(NCACHE_NODEID) */

    {

#    if defined(NCACHE_NODEID)
        if ((*hp)->id == i && (*hp)->na == na)
#    else  /* !defined(NCACHE_NODEID) */
        if ((*hp)->na == na)
#    endif /* defined(NCACHE_NODEID) */

            return (*hp);
    }
    return ((struct l_nch *)NULL);
}

#    if !defined(NCACHE_NO_ROOT)
/*
 * ncache_isroot() - is head of name cache path a file system root?
 */

static int ncache_isroot(struct lsof_context *ctx,
                         KA_T na,  /* kernel node address */
                         char *cp) /* partial path */
{
    char buf[MAXPATHLEN];
    int i;
    MALLOC_S len;
    struct mounts *mtp;
    static int nca = 0;
    static int ncn = 0;
    static KA_T *nc = (KA_T *)NULL;
    struct stat sb;
    struct vnode v;

    if (!na)
        return (0);
    /*
     * Search the root vnode cache.
     */
    for (i = 0; i < ncn; i++) {
        if (na == nc[i])
            return (1);
    }
    /*
     * Read the vnode and see if it's a VDIR node with the NCACHE_VROOT flag
     * set. If it is, then the path is complete.
     *
     * If it isn't, and if the file has an inode number, search the mount table
     * and see if the file system's inode number is known.  If it is, form the
     * possible full path, safely stat() it, and see if it's inode number
     * matches the one we have for this file.  If it does, then the path is
     * complete.
     */
    if (kread(ctx, (KA_T)na, (char *)&v, sizeof(v)) || v.v_type != VDIR ||
        !(v.VNODE_VFLAG & NCACHE_VROOT)) {

        /*
         * The vnode tests failed.  Try the inode tests.
         */
        if (Lf->inp_ty != 1 || !Lf->inode || !Lf->fsdir ||
            (len = strlen(Lf->fsdir)) < 1)
            return (0);
        if ((len + 1 + strlen(cp) + 1) > sizeof(buf))
            return (0);
        for (mtp = readmnt(ctx); mtp; mtp = mtp->next) {
            if (!mtp->dir || !mtp->inode)
                continue;
            if (strcmp(Lf->fsdir, mtp->dir) == 0)
                break;
        }
        if (!mtp)
            return (0);
        (void)strcpy(buf, Lf->fsdir);
        if (buf[len - 1] != '/')
            buf[len++] = '/';
        (void)strcpy(&buf[len], cp);
        if (statsafely(ctx, buf, &sb) != 0 ||
            (unsigned long)sb.st_ino != Lf->inode)
            return (0);
    }
    /*
     * Add the node address to the root node cache.
     */
    if (ncn >= nca) {
        if (!nca) {
            len = (MALLOC_S)(10 * sizeof(KA_T));
            nc = (KA_T *)malloc(len);
        } else {
            len = (MALLOC_S)((nca + 10) * sizeof(KA_T));
            nc = (KA_T *)realloc(nc, len);
        }
        if (!nc) {
            (void)fprintf(stderr, "%s: no space for root node table\n", Pn);
            Error(ctx);
        }
        nca += 10;
    }
    nc[ncn++] = na;
    return (1);
}
#    endif /* !defined(NCACHE_NO_ROOT) */

/*
 * ncache_load() - load the kernel's name cache
 */

void ncache_load(struct lsof_context *ctx) {
    struct NCACHE c;
    struct l_nch **hp, *ln;
    KA_T ka, knx;
    static struct NCACHE **khp = (struct namecache **)NULL;
    static int khpl = 0;
    NCACHE_SZ_CAST khsz;
    unsigned long kx;
    static struct l_nch *lc = (struct l_nch *)NULL;
    static int lcl = 0;
    int len, lim, n, nch, nchl, nlcl;
    char tbuf[32];
    KA_T v;

#    if !defined(NCHNAMLEN)
    int cin = sizeof(c.NCACHE_NM);
    KA_T nmo = (KA_T)offsetof(struct NCACHE, NCACHE_NM);
#    endif /* !defined(NCHNAMLEN) */

#    if !defined(NCACHE_NMLEN)
    char nbf[MAXPATHLEN + 1];
    int nbfl = (int)(sizeof(nbf) - 1);
    KA_T nk;
    char *np;
    int rl;

    nbf[nbfl] = '\0';
#    endif /* !defined(NCACHE_NMLEN) */

    if (!Fncache)
        return;
    /*
     * Free previously allocated space.
     */
    for (lc = Ncache; lc; lc = ln) {
        ln = lc->next;
        (void)free((FREE_P *)lc);
    }
    Ncache = (struct l_nch *)NULL;
    if (Nchash)
        (void)free((FREE_P *)Nchash);
    Nchash = (struct l_nch **)NULL;
    /*
     * Get kernel cache hash table size
     */
    v = (KA_T)0;
    if (get_Nl_value(ctx, X_NCSIZE, (struct drive_Nl *)NULL, &v) < 0 || !v ||
        kread(ctx, (KA_T)v, (char *)&khsz, sizeof(khsz))) {
        if (!Fwarn)
            (void)fprintf(stderr,
                          "%s: WARNING: can't read name cache hash size: %s\n",
                          Pn, print_kptr(v, (char *)NULL, 0));
        return;
    }
    if (khsz < 1) {
        if (!Fwarn)
            (void)fprintf(
                stderr,
                "%s: WARNING: name cache hash size length error: %#lx\n", Pn,
                khsz);
        return;
    }
    /*
     * Get kernel cache hash table address.
     */
    ka = (KA_T)0;
    v = (KA_T)0;
    if (get_Nl_value(ctx, X_NCACHE, (struct drive_Nl *)NULL, &v) < 0 || !v ||
        kread(ctx, (KA_T)v, (char *)&ka, sizeof(ka)) || !ka) {
        if (!Fwarn)
            (void)fprintf(
                stderr,
                "%s: WARNING: unusable name cache hash pointer: (%s)=%s\n", Pn,
                print_kptr(v, tbuf, sizeof(tbuf)),
                print_kptr(ka, (char *)NULL, 0));
        return;
    }
    /*
     * Allocate space for the hash table pointers and read them.
     */
    len = (MALLOC_S)(khsz * sizeof(struct NCACHE *));
    if (len > khpl) {
        if (khp)
            khp = (struct NCACHE **)realloc((MALLOC_P *)khp, len);
        else
            khp = (struct NCACHE **)malloc(len);
        if (!khp) {
            (void)fprintf(
                stderr,
                "%s: can't allocate %d bytes for name cache hash table\n", Pn,
                len);
            Error(ctx);
        }
        khpl = len;
    }
    if (kread(ctx, (KA_T)ka, (char *)khp, len)) {
        (void)fprintf(stderr,
                      "%s: can't read name cache hash pointers from: %s\n", Pn,
                      print_kptr(ka, (char *)NULL, 0));
        return;
    }
    /*
     * Process the kernel's name cache hash table buckets.
     */
    lim = khsz * 10;
    for (kx = nch = 0; kx < khsz; kx++) {

        /*
         * Loop through the entries for a hash bucket.
         */
        for (ka = (KA_T)khp[kx], n = 0; ka; ka = knx, n++) {
            if (n > lim) {
                if (!Fwarn)
                    (void)fprintf(
                        stderr, "%s: WARNING: name cache hash chain too long\n",
                        Pn);
                break;
            }
            if (kread(ctx, ka, (char *)&c, sizeof(c)))
                break;
            knx = (KA_T)c.NCACHE_NXT;
            if (!c.NCACHE_NODEADDR)
                continue;

#    if defined(NCACHE_NMLEN)
            if ((len = c.NCACHE_NMLEN) < 1)
                continue;
#    else  /* !defined(NCACHE_NMLEN) */
            /*
             * If it's possible to read the first four characters of the name,
             * do so and check for "." and "..".
             */
            if (!c.NCACHE_NM || kread(ctx, (KA_T)c.NCACHE_NM, nbf, 4))
                continue;
            if (nbf[0] == '.') {
                if (!nbf[1] || ((nbf[1] == '.') && !nbf[2]))
                    continue;
            }
            /*
             * Read the rest of the name, 32 characters at a time, until a NUL
             * character has been read or nbfl characters have been read.
             */
            nbf[4] = '\0';
            if ((len = (int)strlen(nbf)) < 4) {
                if (!len)
                    continue;
            } else {
                for (np = &nbf[4]; len < nbfl; np += rl) {
                    if ((rl = nbfl - len) > 32) {
                        rl = 32;
                        nbf[len + rl] = '\0';
                    }
                    nk = (KA_T)((char *)c.NCACHE_NM + len);
                    if (kread(ctx, nk, np, rl)) {
                        rl = -1;
                        break;
                    }
                    rl = (int)strlen(np);
                    len += rl;
                    if (rl < 32)
                        break;
                }
                if (rl < 0)
                    continue;
            }
#    endif /* defined(NCACHE_NMLEN) */

                /*
                 * Allocate a cache entry long enough to contain the name and
                 * move the name to it.
                 */

#    if defined(NCHNAMLEN)
            if (len > NCHNAMLEN)
                continue;
            if (len < 3 && c.NCACHE_NM[0] == '.') {
                if (len == 1 || (len == 2 && c.NCACHE_NM[1] == '.'))
                    continue;
            }
            if ((nlcl = sizeof(struct l_nch)) > lcl)
#    else  /* !defined(NCHNAMLEN) */
            if ((nlcl = sizeof(struct l_nch) + len) > lcl)
#    endif /* defined(NCHNAMLEN) */

            {
                if (lc)
                    lc = (struct l_nch *)realloc(lc, nlcl);
                else
                    lc = (struct l_nch *)malloc(nlcl);
                if (!lc) {
                    (void)fprintf(
                        stderr,
                        "%s: can't allocate %d local name cache bytes\n", Pn,
                        nlcl);
                    Error(ctx);
                }
                lcl = nlcl;
            }

#    if defined(NCHNAMLEN)
            (void)strncpy(lc->nm, c.NCACHE_NM, len);
#    else /* !defined(NCHNAMLEN) */
#        if defined(NCACHE_NMLEN)
            if ((len < 3) && (cin > 1)) {

                /*
                 * If this is a one or two character name, and if NCACHE_NM[]
                 * in c has room for at least two characters, check for "."
                 * and ".." first, ignoring this entry if the name is either.
                 */
                if (len < 3 && c.NCACHE_NM[0] == '.') {
                    if (len == 1 || (len == 2 && c.NCACHE_NM[1] == '.'))
                        continue;
                }
            }
            if (len > cin) {

                /*
                 * If not all (possibly not any, depending on the value in
                 * cin) of the name has yet been read to lc->nm[], read it
                 * or the rest of it.  If it wasn't possible before to check
                 * for "." or "..", do that. too.
                 */
                if (cin > 0)
                    (void)strncpy(lc->nm, c.NCACHE_NM, cin);
                if (kread(ctx, ka + (KA_T)(nmo + cin), &lc->nm[cin], len - cin))
                    continue;
                if ((cin < 2) && (len < 3) && (lc->nm[0] == '.')) {
                    if (len == 1 || (len == 2 && lc->nm[1] == '.'))
                        continue;
                }
            } else
                (void)strncpy(lc->nm, c.NCACHE_NM, len);
#        else  /* !defined(NCACHE_NMLEN) */
            (void)strncpy(lc->nm, nbf, len);
#        endif /* defined(NCACHE_NMLEN) */

#    endif /* defined(NCHNAMLEN) */
            lc->nm[len] = '\0';
            /*
             * Complete the new local cache entry and link it to the previous
             * local cache chain.
             */
            lc->next = Ncache;
            Ncache = lc;
            lc->na = (KA_T)c.NCACHE_NODEADDR;
            lc->nl = len;
            lc->pa = (KA_T)c.NCACHE_PARADDR;
            lc->pla = (struct l_nch *)NULL;

#    if defined(NCACHE_NODEID)
            lc->id = c.NCACHE_NODEID;
            lc->did = c.NCACHE_PARID;
#    endif /* defined(NCACHE_NODEID) */

            lcl = 0;
            lc = (struct l_nch *)NULL;
            nch++;
        }
    }
    /*
     * Reduce memory usage, as required.
     */
    if (!RptTm) {
        (void)free((FREE_P *)khp);
        khp = (struct NCACHE **)NULL;
        khpl = 0;
    }
    if (nch < 1) {
        if (!Fwarn)
            (void)fprintf(stderr, "%s: WARNING: unusable name cache size: %d\n",
                          Pn, nch);
        return;
    }
    /*
     * Build a hash table to locate Ncache entries.
     */
    for (nchl = 1; nchl < nch; nchl <<= 1)
        ;
    nchl <<= 1;
    Mch = nchl - 1;
    len = nchl + nch;
    if (!(Nchash = (struct l_nch **)calloc(len, sizeof(struct l_nch *)))) {
        if (!Fwarn)
            (void)fprintf(
                stderr, "%s: no space for %d local name cache hash pointers\n",
                Pn, len);
        Error(ctx);
    }
    for (lc = Ncache; lc; lc = lc->next) {

#    if defined(NCACHE_NODEID)
        for (hp = ncachehash(lc->id, lc->na),
#    else  /* !defined(NCACHE_NODEID) */
        for (hp = ncachehash(lc->na),
#    endif /* defined(NCACHE_NODEID) */

            n = 1;
             *hp; hp++) {
            if ((*hp)->na == lc->na && strcmp((*hp)->nm, lc->nm) == 0) {
                n = 0;
                break;
            }
        }
        if (n)
            *hp = lc;
        else
            lc->pa = (KA_T)0;
    }
    /*
     * Make a final pass through the local cache and convert parent node
     * addresses to local name cache pointers.
     */
    for (lc = Ncache; lc; lc = lc->next) {
        if (!lc->pa)
            continue;

#    if defined(NCACHE_NODEID)
        lc->pla = ncache_addr(lc->did, lc->pa);
#    else  /* !defined(NCACHE_NODEID) */
        lc->pla = ncache_addr(lc->pa);
#    endif /* defined(NCACHE_NODEID) */
    }
}

/*
 * ncache_lookup() - look up a node's name in the kernel's name cache
 */

char *ncache_lookup(struct lsof_context *ctx,
                    char *buf, /* receiving name buffer */
                    int blen,  /* receiving buffer length */
                    int *fp)   /* full path reply */
{
    char *cp = buf;
    struct l_nch *lc;
    struct mounts *mtp;
    int nl, rlen;

    *cp = '\0';
    *fp = 0;

#    if defined(HASFSINO)
    /*
     * If the entry has an inode number that matches the inode number of the
     * file system mount point, return an empty path reply.  That tells the
     * caller to print the file system mount point name only.
     */
    if ((Lf->inp_ty == 1) && Lf->fs_ino && (Lf->inode == Lf->fs_ino))
        return (cp);
#    endif /* defined(HASFSINO) */

        /*
         * Look up the name cache entry for the node address.
         */

#    if defined(NCACHE_NODEID)
    if (!Nchash || !(lc = ncache_addr(Lf->id, Lf->na)))
#    else  /* !defined(NCACHE_NODEID) */
    if (!Nchash || !(lc = ncache_addr(Lf->na)))
#    endif /* defined(NCACHE_NODEID) */

    {

        /*
         * If the node has no cache entry, see if it's the mount
         * point of a known file system.
         */
        if (!Lf->fsdir || !Lf->dev_def || Lf->inp_ty != 1)
            return ((char *)NULL);
        for (mtp = readmnt(ctx); mtp; mtp = mtp->next) {
            if (!mtp->dir || !mtp->inode)
                continue;
            if (Lf->dev == mtp->dev && mtp->inode == Lf->inode &&
                (strcmp(mtp->dir, Lf->fsdir) == 0))
                return (cp);
        }
        return ((char *)NULL);
    }
    /*
     * Start the path assembly.
     */
    if ((nl = lc->nl) > (blen - 1))
        return ((char *)NULL);
    cp = buf + blen - nl - 1;
    rlen = blen - nl - 1;
    (void)strcpy(cp, lc->nm);
    /*
     * Look up the name cache entries that are parents of the node address.
     * Quit when:
     *
     *	there's no parent;
     *	the name length is too large to fit in the receiving buffer.
     */
    for (;;) {
        if (!lc->pla) {

#    if !defined(NCACHE_NO_ROOT)
            if (ncache_isroot(ctx, lc->pa, cp))
                *fp = 1;
#    endif /* !defined(NCACHE_NO_ROOT) */

            break;
        }
        lc = lc->pla;
        if (((nl = lc->nl) + 1) > rlen)
            break;
        *(cp - 1) = '/';
        cp--;
        rlen--;
        (void)strncpy((cp - nl), lc->nm, nl);
        cp -= nl;
        rlen -= nl;
    }
    return (cp);
}
#else  /* !defined(HASNCACHE) || !defined(USE_LIB_RNMH) */
char rnmh_d1[] = "d";
char *rnmh_d2 = rnmh_d1;
#endif /* defined(HASNCACHE) && defined(USE_LIB_RNMH) */