/* $NetBSD: rm.c,v 1.53 2013/04/26 18:43:22 christos 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/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 <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <bsd/stdlib.h>
#include <string.h>
#include <bsd/string.h>
#include <unistd.h>
static int dflag, eval, fflag, iflag, Pflag, stdin_ok, vflag, Wflag;
static int xflag;
static sig_atomic_t pinfo;
static int check(char *, char *, struct stat *);
static void checkdot(char **);
static void progress(int);
static void rm_file(char **);
static int rm_overwrite(char *, struct stat *);
static void rm_tree(char **);
static void usage(void);
/*
* 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 = xflag = 0;
while ((ch = getopt(argc, argv, "dfiPRrvWx")) != -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 'x':
xflag = 1;
break;
case 'W':
Wflag = 1;
break;
case '?':
default:
usage();
}
argc -= optind;
argv += optind;
if (argc < 1) {
if (fflag)
return 0;
usage();
}
(void)signal(SIGHUP, progress);
checkdot(argv);
if (*argv) {
stdin_ok = isatty(STDIN_FILENO);
if (rflag)
rm_tree(argv);
else
rm_file(argv);
}
exit(eval);
/* NOTREACHED */
}
static 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 (xflag)
flags |= FTS_XDEV;
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;
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 || pinfo) {
pinfo = 0;
(void)printf("%s\n", p->fts_path);
}
}
if (errno)
err(1, "fts_read");
fts_close(fts);
}
static 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_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 (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.
*/
static int
rm_overwrite(char *file, struct stat *sbp)
{
struct stat sb, sb2;
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|O_NOFOLLOW, 0)) == -1)
goto err;
if (fstat(fd, &sb2)) {
goto err;
}
if (sb2.st_dev != sbp->st_dev || sb2.st_ino != sbp->st_ino ||
!S_ISREG(sb2.st_mode)) {
errno = EPERM;
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;
}
static int
check(char *path, char *name, struct stat *sp)
{
int ch, first;
char modep[15];
struct passwd *user;
struct group *group;
char username[10], groupname[10];
/* 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;
}
user = getpwuid(sp->st_uid);
group = getgrgid(sp->st_gid);
if (user == NULL) {
snprintf(username, 10, "%d", sp->st_uid);
}
if (group == NULL) {
snprintf(groupname, 10, "%d", sp->st_gid);
}
(void)fprintf(stderr, "override %s%s%s:%s for '%s'? ",
modep + 1, modep[9] == ' ' ? "" : " ",
username, groupname, 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])))
static 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;
}
}
static void
usage(void)
{
(void)fprintf(stderr, "usage: %s [-f|-i] [-dPRrvWx] file ...\n",
getprogname());
exit(1);
/* NOTREACHED */
}
static void
progress(int sig)
{
pinfo++;
}
