Patrick Welche <prlw1@cam.ac.uk>

[netbsd-mini2440.git] / bin / rm / rm.c

/* $NetBSD: rm.c,v 1.48 2008/07/20 00:52:40 lukem Exp $ */

/*-
 * Copyright (c) 1990, 1993, 1994, 2003
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1990, 1993, 1994\
 The Regents of the University of California.  All rights reserved.");
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)rm.c        8.8 (Berkeley) 4/27/95";
#else
__RCSID("$NetBSD: rm.c,v 1.48 2008/07/20 00:52:40 lukem Exp $");
#endif
#endif /* not lint */

#include <sys/param.h>
#include <sys/stat.h>
#include <sys/types.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <fts.h>
#include <grp.h>
#include <locale.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

int dflag, eval, fflag, iflag, Pflag, stdin_ok, vflag, Wflag;

int     check(char *, char *, struct stat *);
void    checkdot(char **);
void    rm_file(char **);
int     rm_overwrite(char *, struct stat *);
void    rm_tree(char **);
void    usage(void);
int     main(int, char *[]);

/*
 * For the sake of the `-f' flag, check whether an error number indicates the
 * failure of an operation due to an non-existent file, either per se (ENOENT)
 * or because its filename argument was illegal (ENAMETOOLONG, ENOTDIR).
 */
#define NONEXISTENT(x) \
    ((x) == ENOENT || (x) == ENAMETOOLONG || (x) == ENOTDIR)

/*
 * rm --
 *      This rm is different from historic rm's, but is expected to match
 *      POSIX 1003.2 behavior.  The most visible difference is that -f
 *      has two specific effects now, ignore non-existent files and force
 *      file removal.
 */
int
main(int argc, char *argv[])
{
        int ch, rflag;

        setprogname(argv[0]);
        (void)setlocale(LC_ALL, "");

        Pflag = rflag = 0;
        while ((ch = getopt(argc, argv, "dfiPRrvW")) != -1)
                switch (ch) {
                case 'd':
                        dflag = 1;
                        break;
                case 'f':
                        fflag = 1;
                        iflag = 0;
                        break;
                case 'i':
                        fflag = 0;
                        iflag = 1;
                        break;
                case 'P':
                        Pflag = 1;
                        break;
                case 'R':
                case 'r':                       /* Compatibility. */
                        rflag = 1;
                        break;
                case 'v':
                        vflag = 1;
                        break;
                case 'W':
                        Wflag = 1;
                        break;
                case '?':
                default:
                        usage();
                }
        argc -= optind;
        argv += optind;

        if (argc < 1) {
                if (fflag)
                        return 0;
                usage();
        }

        checkdot(argv);

        if (*argv) {
                stdin_ok = isatty(STDIN_FILENO);

                if (rflag)
                        rm_tree(argv);
                else
                        rm_file(argv);
        }

        exit(eval);
        /* NOTREACHED */
}

void
rm_tree(char **argv)
{
        FTS *fts;
        FTSENT *p;
        int flags, needstat, rval;
                        
        /*
         * Remove a file hierarchy.  If forcing removal (-f), or interactive
         * (-i) or can't ask anyway (stdin_ok), don't stat the file.
         */
        needstat = !fflag && !iflag && stdin_ok;

        /*
         * If the -i option is specified, the user can skip on the pre-order
         * visit.  The fts_number field flags skipped directories.
         */
#define SKIPPED 1

        flags = FTS_PHYSICAL;
        if (!needstat)
                flags |= FTS_NOSTAT;
        if (Wflag)
                flags |= FTS_WHITEOUT;
        if ((fts = fts_open(argv, flags, NULL)) == NULL)
                err(1, "fts_open failed");
        while ((p = fts_read(fts)) != NULL) {
        
                switch (p->fts_info) {
                case FTS_DNR:
                        if (!fflag || p->fts_errno != ENOENT) {
                                warnx("%s: %s", p->fts_path,
                                                strerror(p->fts_errno));
                                eval = 1;
                        }
                        continue;
                case FTS_ERR:
                        errx(EXIT_FAILURE, "%s: %s", p->fts_path,
                                        strerror(p->fts_errno));
                        /* NOTREACHED */
                case FTS_NS:
                        /*
                         * FTS_NS: assume that if can't stat the file, it
                         * can't be unlinked.
                         */
                        if (fflag && NONEXISTENT(p->fts_errno))
                                continue;
                        if (needstat) {
                                warnx("%s: %s", p->fts_path,
                                                strerror(p->fts_errno));
                                eval = 1;
                                continue;
                        }
                        break;
                case FTS_D:
                        /* Pre-order: give user chance to skip. */
                        if (!fflag && !check(p->fts_path, p->fts_accpath,
                            p->fts_statp)) {
                                (void)fts_set(fts, p, FTS_SKIP);
                                p->fts_number = SKIPPED;
                        }
                        continue;
                case FTS_DP:
                        /* Post-order: see if user skipped. */
                        if (p->fts_number == SKIPPED)
                                continue;
                        break;
                default:
                        if (!fflag &&
                            !check(p->fts_path, p->fts_accpath, p->fts_statp))
                                continue;
                }

                rval = 0;
                /*
                 * If we can't read or search the directory, may still be
                 * able to remove it.  Don't print out the un{read,search}able
                 * message unless the remove fails.
                 */
                switch (p->fts_info) {
                case FTS_DP:
                case FTS_DNR:
                        rval = rmdir(p->fts_accpath);
                        if (rval != 0 && fflag && errno == ENOENT)
                                continue;
                        break;

                case FTS_W:
                        rval = undelete(p->fts_accpath);
                        if (rval != 0 && fflag && errno == ENOENT)
                                continue;
                        break;

                default:
                        if (Pflag) {
                                if (rm_overwrite(p->fts_accpath, NULL))
                                        continue;
                        }
                        rval = unlink(p->fts_accpath);
                        if (rval != 0 && fflag && NONEXISTENT(errno))
                                continue;
                        break;
                }
                if (rval != 0) {
                        warn("%s", p->fts_path);
                        eval = 1;
                } else if (vflag)
                        (void)printf("%s\n", p->fts_path);
        }
        if (errno)
                err(1, "fts_read");
        fts_close(fts);
}

void
rm_file(char **argv)
{
        struct stat sb;
        int rval;
        char *f;

        /*
         * Remove a file.  POSIX 1003.2 states that, by default, attempting
         * to remove a directory is an error, so must always stat the file.
         */
        while ((f = *argv++) != NULL) {
                /* Assume if can't stat the file, can't unlink it. */
                if (lstat(f, &sb)) {
                        if (Wflag) {
                                sb.st_mode = S_IFWHT|S_IWUSR|S_IRUSR;
                        } else {
                                if (!fflag || !NONEXISTENT(errno)) {
                                        warn("%s", f);
                                        eval = 1;
                                }
                                continue;
                        }
                } else if (Wflag) {
                        warnx("%s: %s", f, strerror(EEXIST));
                        eval = 1;
                        continue;
                }

                if (S_ISDIR(sb.st_mode) && !dflag) {
                        warnx("%s: is a directory", f);
                        eval = 1;
                        continue;
                }
                if (!fflag && !S_ISWHT(sb.st_mode) && !check(f, f, &sb))
                        continue;
                if (S_ISWHT(sb.st_mode))
                        rval = undelete(f);
                else if (S_ISDIR(sb.st_mode))
                        rval = rmdir(f);
                else {
                        if (Pflag) {
                                if (rm_overwrite(f, &sb))
                                        continue;
                        }
                        rval = unlink(f);
                }
                if (rval && (!fflag || !NONEXISTENT(errno))) {
                        warn("%s", f);
                        eval = 1;
                }
                if (vflag && rval == 0)
                        (void)printf("%s\n", f);
        }
}

/*
 * rm_overwrite --
 *      Overwrite the file 3 times with varying bit patterns.
 *
 * This is an expensive way to keep people from recovering files from your
 * non-snapshotted FFS filesystems using fsdb(8).  Really.  No more.  Only
 * regular files are deleted, directories (and therefore names) will remain.
 * Also, this assumes a fixed-block file system (like FFS, or a V7 or a
 * System V file system).  In a logging file system, you'll have to have
 * kernel support.
 *
 * A note on standards:  U.S. DoD 5220.22-M "National Industrial Security
 * Program Operating Manual" ("NISPOM") is often cited as a reference
 * for clearing and sanitizing magnetic media.  In fact, a matrix of
 * "clearing" and "sanitization" methods for various media was given in
 * Chapter 8 of the original 1995 version of NISPOM.  However, that
 * matrix was *removed from the document* when Chapter 8 was rewritten
 * in Change 2 to the document in 2001.  Recently, the Defense Security
 * Service has made a revised clearing and sanitization matrix available
 * in Microsoft Word format on the DSS web site.  The standardization
 * status of this matrix is unclear.  Furthermore, one must be very
 * careful when referring to this matrix: it is intended for the "clearing"
 * prior to reuse or "sanitization" prior to disposal of *entire media*,
 * not individual files and the only non-physically-destructive method of
 * "sanitization" that is permitted for magnetic disks of any kind is
 * specifically noted to be prohibited for media that have contained
 * Top Secret data.
 *
 * It is impossible to actually conform to the exact procedure given in
 * the matrix if one is overwriting a file, not an entire disk, because
 * the procedure requires examination and comparison of the disk's defect
 * lists.  Any program that claims to securely erase *files* while 
 * conforming to the standard, then, is not correct.  We do as much of
 * what the standard requires as can actually be done when erasing a
 * file, rather than an entire disk; but that does not make us conformant.
 *
 * Furthermore, the presence of track caches, disk and controller write
 * caches, and so forth make it extremely difficult to ensure that data
 * have actually been written to the disk, particularly when one tries
 * to repeatedly overwrite the same sectors in quick succession.  We call
 * fsync(), but controllers with nonvolatile cache, as well as IDE disks
 * that just plain lie about the stable storage of data, will defeat this.
 *
 * Finally, widely respected research suggests that the given procedure
 * is nowhere near sufficient to prevent the recovery of data using special
 * forensic equipment and techniques that are well-known.  This is 
 * presumably one reason that the matrix requires physical media destruction,
 * rather than any technique of the sort attempted here, for secret data.
 *
 * Caveat Emptor.
 *
 * rm_overwrite will return 0 on success.
 */

int
rm_overwrite(char *file, struct stat *sbp)
{
        struct stat sb;
        int fd, randint;
        char randchar;

        fd = -1;
        if (sbp == NULL) {
                if (lstat(file, &sb))
                        goto err;
                sbp = &sb;
        }
        if (!S_ISREG(sbp->st_mode))
                return 0;

        /* flags to try to defeat hidden caching by forcing seeks */
        if ((fd = open(file, O_RDWR|O_SYNC|O_RSYNC, 0)) == -1)
                goto err;

#define RAND_BYTES      1
#define THIS_BYTE       0

#define WRITE_PASS(mode, byte) do {                                     \
        off_t len;                                                      \
        size_t wlen, i;                                                 \
        char buf[8 * 1024];                                             \
                                                                        \
        if (fsync(fd) || lseek(fd, (off_t)0, SEEK_SET))                 \
                goto err;                                               \
                                                                        \
        if (mode == THIS_BYTE)                                          \
                memset(buf, byte, sizeof(buf));                         \
        for (len = sbp->st_size; len > 0; len -= wlen) {                \
                if (mode == RAND_BYTES) {                               \
                        for (i = 0; i < sizeof(buf);                    \
                            i+= sizeof(u_int32_t))                      \
                                *(int *)(buf + i) = arc4random();       \
                }                                                       \
                wlen = len < (off_t)sizeof(buf) ? (size_t)len : sizeof(buf); \
                if ((size_t)write(fd, buf, wlen) != wlen)               \
                        goto err;                                       \
        }                                                               \
        sync();         /* another poke at hidden caches */             \
} while (/* CONSTCOND */ 0)

#define READ_PASS(byte) do {                                            \
        off_t len;                                                      \
        size_t rlen;                                                    \
        char pattern[8 * 1024];                                         \
        char buf[8 * 1024];                                             \
                                                                        \
        if (fsync(fd) || lseek(fd, (off_t)0, SEEK_SET))                 \
                goto err;                                               \
                                                                        \
        memset(pattern, byte, sizeof(pattern));                         \
        for(len = sbp->st_size; len > 0; len -= rlen) {                 \
                rlen = len < (off_t)sizeof(buf) ? (size_t)len : sizeof(buf); \
                if((size_t)read(fd, buf, rlen) != rlen)                 \
                        goto err;                                       \
                if(memcmp(buf, pattern, rlen))                          \
                        goto err;                                       \
        }                                                               \
        sync();         /* another poke at hidden caches */             \
} while (/* CONSTCOND */ 0)

        /*
         * DSS sanitization matrix "clear" for magnetic disks: 
         * option 'c' "Overwrite all addressable locations with a single 
         * character."
         */
        randint = arc4random();
        randchar = *(char *)&randint;
        WRITE_PASS(THIS_BYTE, randchar);

        /*
         * DSS sanitization matrix "sanitize" for magnetic disks: 
         * option 'd', sub 2 "Overwrite all addressable locations with a
         * character, then its complement.  Verify "complement" character
         * was written successfully to all addressable locations, then
         * overwrite all addressable locations with random characters; or
         * verify third overwrite of random characters."  The rest of the
         * text in d-sub-2 specifies requirements for overwriting spared
         * sectors; we cannot conform to it when erasing only a file, thus
         * we do not conform to the standard.
         */

        /* 1. "a character" */
        WRITE_PASS(THIS_BYTE, 0xff);

        /* 2. "its complement" */
        WRITE_PASS(THIS_BYTE, 0x00);

        /* 3. "Verify 'complement' character" */
        READ_PASS(0x00);

        /* 4. "overwrite all addressable locations with random characters" */

        WRITE_PASS(RAND_BYTES, 0x00);

        /*
         * As the file might be huge, and we note that this revision of
         * the matrix says "random characters", not "a random character"
         * as the original did, we do not verify the random-character
         * write; the "or" in the standard allows this.
         */

        if (close(fd) == -1) {
                fd = -1;
                goto err;
        }

        return 0;

err:    eval = 1;
        warn("%s", file);
        if (fd != -1)
                close(fd);
        return 1;
}

int
check(char *path, char *name, struct stat *sp)
{
        int ch, first;
        char modep[15];

        /* Check -i first. */
        if (iflag)
                (void)fprintf(stderr, "remove '%s'? ", path);
        else {
                /*
                 * If it's not a symbolic link and it's unwritable and we're
                 * talking to a terminal, ask.  Symbolic links are excluded
                 * because their permissions are meaningless.  Check stdin_ok
                 * first because we may not have stat'ed the file.
                 */
                if (!stdin_ok || S_ISLNK(sp->st_mode) ||
                    !(access(name, W_OK) && (errno != ETXTBSY)))
                        return (1);
                strmode(sp->st_mode, modep);
                if (Pflag) {
                        warnx(
                            "%s: -P was specified but file could not"
                            " be overwritten", path);
                        return 0;
                }
                (void)fprintf(stderr, "override %s%s%s:%s for '%s'? ",
                    modep + 1, modep[9] == ' ' ? "" : " ",
                    user_from_uid(sp->st_uid, 0),
                    group_from_gid(sp->st_gid, 0), path);
        }
        (void)fflush(stderr);

        first = ch = getchar();
        while (ch != '\n' && ch != EOF)
                ch = getchar();
        return (first == 'y' || first == 'Y');
}

/*
 * POSIX.2 requires that if "." or ".." are specified as the basename
 * portion of an operand, a diagnostic message be written to standard
 * error and nothing more be done with such operands.
 *
 * Since POSIX.2 defines basename as the final portion of a path after
 * trailing slashes have been removed, we'll remove them here.
 */
#define ISDOT(a) ((a)[0] == '.' && (!(a)[1] || ((a)[1] == '.' && !(a)[2])))
void
checkdot(char **argv)
{
        char *p, **save, **t;
        int complained;

        complained = 0;
        for (t = argv; *t;) {
                /* strip trailing slashes */
                p = strrchr(*t, '\0');
                while (--p > *t && *p == '/')
                        *p = '\0';

                /* extract basename */
                if ((p = strrchr(*t, '/')) != NULL)
                        ++p;
                else
                        p = *t;

                if (ISDOT(p)) {
                        if (!complained++)
                                warnx("\".\" and \"..\" may not be removed");
                        eval = 1;
                        for (save = t; (t[0] = t[1]) != NULL; ++t)
                                continue;
                        t = save;
                } else
                        ++t;
        }
}

void
usage(void)
{

        (void)fprintf(stderr, "usage: %s [-f|-i] [-dPRrvW] file ...\n",
            getprogname());
        exit(1);
        /* NOTREACHED */
}