ref: 61cc0694649a4d4b109d168032f431751f57f083
dir: /sys/src/cmd/auth/keyfs.c/
/*
* keyfs
*/
#include <u.h>
#include <libc.h>
#include <ctype.h>
#include <fcall.h>
#include <bio.h>
#include <libsec.h>
#include <authsrv.h>
#include "authcmdlib.h"
#pragma varargck type "W" char*
Authkey authkey;
int keydbaes;
uchar zeros[16];
typedef struct Fid Fid;
typedef struct User User;
enum {
Qroot,
Quser,
Qkey,
Qaeskey,
Qpakhash,
Qsecret,
Qlog,
Qstatus,
Qexpire,
Qwarnings,
Qmax,
Nuser = 512,
MAXBAD = 10, /* max # of bad attempts before disabling the account */
/* file must be randomly addressible, so names have fixed length */
Namelen = ANAMELEN,
};
enum {
Sok,
Sdisabled,
Smax,
};
struct Fid {
int fid;
ulong qtype;
User *user;
int busy;
Fid *next;
};
struct User {
char *name;
Authkey key;
char secret[SECRETLEN];
ulong expire; /* 0 == never */
uchar status;
ulong bad; /* # of consecutive bad authentication attempts */
int ref;
char removed;
uchar warnings;
ulong purgatory; /* time purgatory ends */
ulong uniq;
User *link;
};
char *qinfo[Qmax] = {
[Qroot] "keys",
[Quser] ".",
[Qkey] "key",
[Qaeskey] "aeskey",
[Qpakhash] "pakhash",
[Qsecret] "secret",
[Qlog] "log",
[Qexpire] "expire",
[Qstatus] "status",
[Qwarnings] "warnings",
};
char *status[Smax] = {
[Sok] "ok",
[Sdisabled] "disabled",
};
Fid *fids;
User *users[Nuser];
char *userkeys;
int nuser;
ulong uniq = 1;
Fcall rhdr, thdr;
int usepass;
int readonly;
char *warnarg;
uchar mdata[8192 + IOHDRSZ];
int messagesize = sizeof mdata;
int readusers(void);
ulong hash(char*);
Fid *findfid(int);
User *finduser(char*);
User *installuser(char*);
int removeuser(User*);
void insertuser(User*);
void writeusers(void);
void io(int, int);
void *emalloc(ulong);
char *estrdup(char*);
Qid mkqid(User*, ulong);
int dostat(User*, ulong, void*, int);
int newkeys(void);
void warning(void);
int weirdfmt(Fmt *f);
char *Auth(Fid*), *Attach(Fid*), *Version(Fid*),
*Flush(Fid*), *Walk(Fid*),
*Open(Fid*), *Create(Fid*),
*Read(Fid *), *Write(Fid*), *Clunk(Fid*),
*Remove(Fid *), *Stat(Fid*), *Wstat(Fid*);
char *(*fcalls[])(Fid*) = {
[Tattach] Attach,
[Tauth] Auth,
[Tclunk] Clunk,
[Tcreate] Create,
[Tflush] Flush,
[Topen] Open,
[Tread] Read,
[Tremove] Remove,
[Tstat] Stat,
[Tversion] Version,
[Twalk] Walk,
[Twrite] Write,
[Twstat] Wstat,
};
static void
usage(void)
{
fprint(2, "usage: %s [-p] [-r] [-m mtpt] [-w warn] [keyfile]\n", argv0);
exits("usage");
}
static int
haveaeskey(void)
{
return memcmp(authkey.aes, zeros, 16) != 0;
}
void
main(int argc, char *argv[])
{
char *mntpt;
int p[2];
fmtinstall('W', weirdfmt);
mntpt = "/mnt/keys";
ARGBEGIN{
case 'm':
mntpt = EARGF(usage());
break;
case 'p':
usepass = 1;
break;
case 'w':
warnarg = EARGF(usage());
break;
case 'r':
readonly = 1;
break;
default:
usage();
break;
}ARGEND
argv0 = "keyfs";
userkeys = "/adm/keys";
if(argc > 1)
usage();
if(argc == 1)
userkeys = argv[0];
if(pipe(p) < 0)
error("can't make pipe: %r");
private();
if(usepass)
getpass(&authkey, nil, 0, 0);
else {
if(!getauthkey(&authkey))
fprint(2, "keyfs: warning: can't read NVRAM\n");
}
keydbaes = 0;
if(!newkeys() || !readusers()){
if(!keydbaes)
keydbaes = haveaeskey();
else if(!haveaeskey()){
fprint(2, "keyfs: no aes key in NVRAM\n");
getpass(&authkey, nil, 0, 0);
readusers();
}
}
switch(rfork(RFPROC|RFNAMEG|RFNOTEG|RFNOWAIT|RFENVG|RFFDG)){
case 0:
close(p[0]);
io(p[1], p[1]);
exits(0);
case -1:
error("fork");
default:
close(p[1]);
if(mount(p[0], -1, mntpt, MREPL|MCREATE, "") == -1)
error("can't mount: %r");
exits(0);
}
}
char *
Flush(Fid *f)
{
USED(f);
return 0;
}
char *
Auth(Fid *)
{
return "keyfs: authentication not required";
}
char *
Attach(Fid *f)
{
if(f->busy)
Clunk(f);
f->user = nil;
f->qtype = Qroot;
f->busy = 1;
thdr.qid = mkqid(f->user, f->qtype);
return 0;
}
char*
Version(Fid*)
{
Fid *f;
for(f = fids; f; f = f->next)
if(f->busy)
Clunk(f);
if(rhdr.msize < 256)
return "message size too small";
if(rhdr.msize > sizeof mdata)
thdr.msize = sizeof mdata;
else
thdr.msize = rhdr.msize;
messagesize = thdr.msize;
thdr.version = "9P2000";
if(strncmp(rhdr.version, "9P", 2) != 0)
thdr.version = "unknown";
return 0;
}
char *
Walk(Fid *f)
{
char *name, *err;
int i, j, max;
Fid *nf;
ulong qtype;
User *user;
if(!f->busy)
return "walk of unused fid";
nf = nil;
qtype = f->qtype;
user = f->user;
if(rhdr.fid != rhdr.newfid){
nf = findfid(rhdr.newfid);
if(nf->busy)
return "fid in use";
f = nf; /* walk f */
}
err = nil;
i = 0;
if(rhdr.nwname > 0){
for(; i<rhdr.nwname; i++){
if(i >= MAXWELEM){
err = "too many path name elements";
break;
}
name = rhdr.wname[i];
switch(qtype){
case Qroot:
if(strcmp(name, "..") == 0)
goto Accept;
user = finduser(name);
if(user == nil)
goto Out;
qtype = Quser;
Accept:
thdr.wqid[i] = mkqid(user, qtype);
break;
case Quser:
if(strcmp(name, "..") == 0) {
qtype = Qroot;
user = nil;
goto Accept;
}
max = Qmax;
for(j = Quser + 1; j < Qmax; j++)
if(strcmp(name, qinfo[j]) == 0){
qtype = j;
break;
}
if(j < max)
goto Accept;
goto Out;
default:
err = "file is not a directory";
goto Out;
}
}
Out:
if(i < rhdr.nwname && err == nil)
err = "file not found";
}
if(err != nil){
return err;
}
/* if we cloned and then completed the walk, update new fid */
if(rhdr.fid != rhdr.newfid && i == rhdr.nwname){
nf->busy = 1;
nf->qtype = qtype;
nf->user = user;
if(user != nil)
user->ref++;
}else if(nf == nil && rhdr.nwname > 0){ /* walk without clone (rare) */
Clunk(f);
f->busy = 1;
f->qtype = qtype;
f->user = user;
if(user != nil)
user->ref++;
}
thdr.nwqid = i;
return 0;
}
char *
Clunk(Fid *f)
{
f->busy = 0;
if(f->user != nil && --f->user->ref == 0 && f->user->removed) {
free(f->user->name);
free(f->user);
}
f->user = nil;
return nil;
}
char *
Open(Fid *f)
{
int mode;
if(!f->busy)
return "open of unused fid";
mode = rhdr.mode;
if(f->qtype == Quser && (mode & (OWRITE|OTRUNC)))
return "user already exists";
if((f->qtype == Qaeskey || f->qtype == Qpakhash) && !keydbaes)
return "keyfile not in aes format";
thdr.qid = mkqid(f->user, f->qtype);
thdr.iounit = messagesize - IOHDRSZ;
return 0;
}
char *
Create(Fid *f)
{
char *name;
long perm;
if(!f->busy)
return "create of unused fid";
if(readonly)
return "mounted read-only";
name = rhdr.name;
if(f->user != nil){
return "permission denied";
}else{
perm = rhdr.perm;
if(!(perm & DMDIR))
return "permission denied";
if(strcmp(name, "") == 0)
return "empty file name";
if(strlen(name) >= Namelen)
return "file name too long";
if(finduser(name) != nil)
return "user already exists";
f->user = installuser(name);
f->user->ref++;
f->qtype = Quser;
}
thdr.qid = mkqid(f->user, f->qtype);
thdr.iounit = messagesize - IOHDRSZ;
writeusers();
return 0;
}
char *
Read(Fid *f)
{
User *u;
char *data;
ulong off, n, m;
int i, j, max;
if(!f->busy)
return "read of unused fid";
n = rhdr.count;
off = rhdr.offset;
thdr.count = 0;
data = thdr.data;
switch(f->qtype){
case Qroot:
j = 0;
for(i = 0; i < Nuser; i++)
for(u = users[i]; u != nil; j += m, u = u->link){
m = dostat(u, Quser, data, n);
if(m <= BIT16SZ)
break;
if(j < off)
continue;
data += m;
n -= m;
}
thdr.count = data - thdr.data;
return 0;
case Quser:
max = Qmax;
max -= Quser + 1;
j = 0;
for(i = 0; i < max; j += m, i++){
m = dostat(f->user, i + Quser + 1, data, n);
if(m <= BIT16SZ)
break;
if(j < off)
continue;
data += m;
n -= m;
}
thdr.count = data - thdr.data;
return 0;
case Qkey:
case Qaeskey:
case Qpakhash:
case Qsecret:
if(f->user->status != Sok)
return "user disabled";
if(f->user->purgatory > (ulong)time(0))
return "user in purgatory";
if(f->user->expire != 0 && f->user->expire < (ulong)time(0))
return "user expired";
m = 0;
switch(f->qtype){
case Qkey:
data = (char*)f->user->key.des;
m = DESKEYLEN;
break;
case Qaeskey:
data = (char*)f->user->key.aes;
m = AESKEYLEN;
break;
case Qpakhash:
data = (char*)f->user->key.pakhash;
m = PAKHASHLEN;
break;
case Qsecret:
data = f->user->secret;
Readstr:
m = strlen(data);
break;
}
if(off >= m)
n = 0;
else {
data += off;
m -= off;
if(n > m)
n = m;
}
if(data != thdr.data)
memmove(thdr.data, data, n);
thdr.count = n;
return 0;
case Qstatus:
if(f->user->status == Sok && f->user->expire && f->user->expire < (ulong)time(0))
sprint(data, "expired\n");
else
sprint(data, "%s\n", status[f->user->status]);
goto Readstr;
case Qexpire:
if(!f->user->expire)
strcpy(data, "never\n");
else
sprint(data, "%lud\n", f->user->expire);
goto Readstr;
case Qlog:
sprint(data, "%lud\n", f->user->bad);
goto Readstr;
case Qwarnings:
sprint(data, "%ud\n", f->user->warnings);
goto Readstr;
default:
return "permission denied: unknown qid";
}
}
char *
Write(Fid *f)
{
char *data, *p;
ulong n, expire;
int i;
if(!f->busy)
return "permission denied";
if(readonly)
return "mounted read-only";
n = rhdr.count;
data = rhdr.data;
switch(f->qtype){
case Qkey:
if(n != DESKEYLEN)
return "garbled write data";
memmove(f->user->key.des, data, n);
thdr.count = n;
break;
case Qaeskey:
if(n != AESKEYLEN)
return "garbled write data";
memmove(f->user->key.aes, data, n);
authpak_hash(&f->user->key, f->user->name);
thdr.count = n;
break;
case Qsecret:
if(n >= SECRETLEN)
return "garbled write data";
memmove(f->user->secret, data, n);
f->user->secret[n] = '\0';
thdr.count = n;
break;
case Qstatus:
data[n] = '\0';
if(p = strchr(data, '\n'))
*p = '\0';
for(i = 0; i < Smax; i++)
if(strcmp(data, status[i]) == 0){
f->user->status = i;
break;
}
if(i == Smax)
return "unknown status";
f->user->bad = 0;
thdr.count = n;
break;
case Qexpire:
data[n] = '\0';
if(p = strchr(data, '\n'))
*p = '\0';
else
p = &data[n];
if(strcmp(data, "never") == 0)
expire = 0;
else{
expire = strtoul(data, &data, 10);
if(data != p)
return "bad expiration date";
}
f->user->expire = expire;
f->user->warnings = 0;
thdr.count = n;
break;
case Qlog:
data[n] = '\0';
if(strcmp(data, "good") == 0)
f->user->bad = 0;
else
f->user->bad++;
if(f->user->bad && ((f->user->bad)%MAXBAD) == 0)
f->user->purgatory = (ulong)time(0) + f->user->bad;
return 0;
case Qwarnings:
data[n] = '\0';
f->user->warnings = strtoul(data, nil, 10);
thdr.count = n;
break;
case Qroot:
case Quser:
default:
return "permission denied";
}
writeusers();
return 0;
}
char *
Remove(Fid *f)
{
if(!f->busy)
return "permission denied";
if(readonly){
Clunk(f);
return "mounted read-only";
}
if(f->qtype == Qwarnings)
f->user->warnings = 0;
else if(f->qtype == Quser)
removeuser(f->user);
else {
Clunk(f);
return "permission denied";
}
Clunk(f);
writeusers();
return 0;
}
char *
Stat(Fid *f)
{
static uchar statbuf[1024];
if(!f->busy)
return "stat on unattached fid";
thdr.nstat = dostat(f->user, f->qtype, statbuf, sizeof statbuf);
if(thdr.nstat <= BIT16SZ)
return "stat buffer too small";
thdr.stat = statbuf;
return 0;
}
char *
Wstat(Fid *f)
{
Dir d;
int n;
char buf[1024];
if(!f->busy || f->qtype != Quser)
return "permission denied";
if(readonly)
return "mounted read-only";
if(rhdr.nstat > sizeof buf)
return "wstat buffer too big";
if(convM2D(rhdr.stat, rhdr.nstat, &d, buf) == 0)
return "bad stat buffer";
n = strlen(d.name);
if(n == 0 || n >= Namelen)
return "bad user name";
if(finduser(d.name))
return "user already exists";
if(!removeuser(f->user))
return "user previously removed";
free(f->user->name);
f->user->name = estrdup(d.name);
insertuser(f->user);
writeusers();
return 0;
}
Qid
mkqid(User *u, ulong qtype)
{
Qid q;
q.vers = 0;
q.path = qtype;
if(u)
q.path |= u->uniq * 0x100;
if(qtype == Quser || qtype == Qroot)
q.type = QTDIR;
else
q.type = QTFILE;
return q;
}
int
dostat(User *user, ulong qtype, void *p, int n)
{
Dir d;
if(qtype == Quser)
d.name = user->name;
else
d.name = qinfo[qtype];
d.uid = d.gid = d.muid = "auth";
d.qid = mkqid(user, qtype);
if(d.qid.type & QTDIR)
d.mode = 0777|DMDIR;
else
d.mode = 0666;
d.atime = d.mtime = time(0);
d.length = 0;
return convD2M(&d, p, n);
}
void
writeusers(void)
{
int keydblen, keydboff;
int fd, i, nu;
User *u;
uchar *p, *buf;
ulong expire;
if(readonly){
fprint(2, "writeusers called while read-only; shouldn't happen\n");
return;
}
/* what format to use */
keydblen = KEYDBLEN;
keydboff = KEYDBOFF;
if(keydbaes){
keydblen += AESKEYLEN;
keydboff = 8+16; /* segnature[8] + iv[16] */
}
/* count users */
nu = 0;
for(i = 0; i < Nuser; i++)
for(u = users[i]; u != nil; u = u->link)
nu++;
/* pack into buffer */
buf = emalloc(keydboff + nu*keydblen);
p = buf;
genrandom(p, keydboff);
p += keydboff;
for(i = 0; i < Nuser; i++)
for(u = users[i]; u != nil; u = u->link){
strncpy((char*)p, u->name, Namelen);
p += Namelen;
memmove(p, u->key.des, DESKEYLEN);
p += DESKEYLEN;
*p++ = u->status;
*p++ = u->warnings;
expire = u->expire;
*p++ = expire;
*p++ = expire >> 8;
*p++ = expire >> 16;
*p++ = expire >> 24;
memmove(p, u->secret, SECRETLEN);
p += SECRETLEN;
if(keydbaes){
memmove(p, u->key.aes, AESKEYLEN);
p += AESKEYLEN;
}
}
/* encrypt */
if(keydbaes){
AESstate s;
memmove(buf, "AES KEYS", 8);
setupAESstate(&s, authkey.aes, AESKEYLEN, zeros);
aesCBCencrypt(buf+8, (p - (buf+8)), &s);
} else {
uchar key[8];
DESstate s;
des56to64((uchar*)authkey.des, key);
setupDESstate(&s, key, zeros);
desCBCencrypt(buf, p - buf, &s);
}
/* write file */
fd = create(userkeys, OWRITE, 0660);
if(fd < 0){
fprint(2, "keyfs: can't write %s: %r\n", userkeys);
free(buf);
return;
}
if(write(fd, buf, p - buf) != (p - buf))
fprint(2, "keyfs: can't write %s: %r\n", userkeys);
close(fd);
free(buf);
newkeys();
}
int
weirdfmt(Fmt *f)
{
char *s, buf[ANAMELEN*4 + 1];
int i, j, n;
Rune r;
s = va_arg(f->args, char*);
j = 0;
for(i = 0; i < ANAMELEN; i += n){
n = chartorune(&r, s + i);
if(r == Runeerror)
j += sprint(buf+j, "[%.2x]", buf[i]);
else if(isascii(r) && iscntrl(r))
j += sprint(buf+j, "[%.2x]", r);
else if(r == ' ' || r == '/')
j += sprint(buf+j, "[%c]", r);
else
j += sprint(buf+j, "%C", r);
}
return fmtstrcpy(f, buf);
}
int
userok(char *user, int nu)
{
int i, n, rv;
Rune r;
char buf[ANAMELEN+1];
memset(buf, 0, sizeof buf);
memmove(buf, user, ANAMELEN);
if(buf[ANAMELEN-1] != 0){
fprint(2, "keyfs: %d: no termination: %W\n", nu, buf);
return -1;
}
rv = 0;
for(i = 0; buf[i]; i += n){
n = chartorune(&r, buf+i);
if(r == Runeerror){
// fprint(2, "keyfs: name %W bad rune byte %d\n", buf, i);
rv = -1;
} else if(isascii(r) && iscntrl(r) || r == ' ' || r == '/'){
// fprint(2, "keyfs: name %W bad char %C\n", buf, r);
rv = -1;
}
}
if(i == 0){
fprint(2, "keyfs: %d: nil name\n", nu);
return -1;
}
if(rv == -1)
fprint(2, "keyfs: %d: bad syntax: %W\n", nu, buf);
return rv;
}
int
readusers(void)
{
int keydblen, keydboff;
int fd, i, n, nu;
uchar *p, *buf, *ep;
User *u;
Dir *d;
/* read file into an array */
fd = open(userkeys, OREAD);
if(fd < 0){
fprint(2, "keyfs: can't read %s: %r\n", userkeys);
return 0;
}
d = dirfstat(fd);
if(d == nil){
close(fd);
return 0;
}
buf = emalloc(d->length);
n = readn(fd, buf, d->length);
close(fd);
free(d);
if(n != d->length){
free(buf);
return 0;
}
keydblen = KEYDBLEN;
keydboff = KEYDBOFF;
keydbaes = n > 24 && memcmp(buf, "AES KEYS", 8) == 0;
/* decrypt */
if(keydbaes){
AESstate s;
/* make sure we have AES encryption key */
if(!haveaeskey()){
free(buf);
return 0;
}
keydblen += AESKEYLEN;
keydboff = 8+16; /* signature[8] + iv[16] */
setupAESstate(&s, authkey.aes, AESKEYLEN, zeros);
aesCBCdecrypt(buf+8, n-8, &s);
} else {
uchar key[8];
DESstate s;
des56to64((uchar*)authkey.des, key);
setupDESstate(&s, key, zeros);
desCBCdecrypt(buf, n, &s);
}
/* unpack */
nu = 0;
n = (n - keydboff) / keydblen;
ep = buf + keydboff;
for(i = 0; i < n; ep += keydblen, i++){
if(userok((char*)ep, i) < 0)
continue;
u = finduser((char*)ep);
if(u == nil)
u = installuser((char*)ep);
memmove(u->key.des, ep + Namelen, DESKEYLEN);
p = ep + Namelen + DESKEYLEN;
u->status = *p++;
u->warnings = *p++;
if(u->status >= Smax)
fprint(2, "keyfs: warning: bad status in key file\n");
u->expire = p[0] + (p[1]<<8) + (p[2]<<16) + (p[3]<<24);
p += 4;
memmove(u->secret, p, SECRETLEN);
u->secret[SECRETLEN-1] = 0;
p += SECRETLEN;
if(keydbaes){
memmove(u->key.aes, p, AESKEYLEN);
authpak_hash(&u->key, u->name);
}
nu++;
}
free(buf);
print("%d keys read in %s format\n", nu, keydbaes ? "AES" : "DES");
return 1;
}
User *
installuser(char *name)
{
User *u;
int h;
h = hash(name);
u = emalloc(sizeof *u);
u->name = estrdup(name);
u->removed = 0;
u->ref = 0;
u->purgatory = 0;
u->expire = 0;
u->status = Sok;
u->bad = 0;
u->warnings = 0;
u->uniq = uniq++;
u->link = users[h];
users[h] = u;
return u;
}
User *
finduser(char *name)
{
User *u;
for(u = users[hash(name)]; u != nil; u = u->link)
if(strcmp(name, u->name) == 0)
return u;
return nil;
}
int
removeuser(User *user)
{
User *u, **last;
char *name;
user->removed = 1;
name = user->name;
last = &users[hash(name)];
for(u = *last; u != nil; u = *last){
if(strcmp(name, u->name) == 0){
*last = u->link;
return 1;
}
last = &u->link;
}
return 0;
}
void
insertuser(User *user)
{
int h;
user->removed = 0;
h = hash(user->name);
user->link = users[h];
users[h] = user;
}
ulong
hash(char *s)
{
ulong h;
h = 0;
while(*s)
h = (h << 1) ^ *s++;
return h % Nuser;
}
Fid *
findfid(int fid)
{
Fid *f, *ff;
ff = nil;
for(f = fids; f != nil; f = f->next)
if(f->fid == fid)
return f;
else if(!ff && !f->busy)
ff = f;
if(ff != nil){
ff->fid = fid;
return ff;
}
f = emalloc(sizeof *f);
f->fid = fid;
f->busy = 0;
f->user = nil;
f->next = fids;
fids = f;
return f;
}
void
io(int in, int out)
{
char *err;
int n;
ulong now, lastwarning;
/* after restart, let the system settle for 5 mins before warning */
lastwarning = (ulong)time(0) - 24*60*60 + 5*60;
while((n = read9pmsg(in, mdata, messagesize)) != 0){
if(n < 0)
error("mount read: %r");
if(convM2S(mdata, n, &rhdr) != n)
error("convM2S format error: %r");
if(newkeys())
readusers();
thdr.data = (char*)mdata + IOHDRSZ;
thdr.fid = rhdr.fid;
if(!fcalls[rhdr.type])
err = "fcall request";
else
err = (*fcalls[rhdr.type])(findfid(rhdr.fid));
thdr.tag = rhdr.tag;
thdr.type = rhdr.type+1;
if(err){
thdr.type = Rerror;
thdr.ename = err;
}
n = convS2M(&thdr, mdata, messagesize);
if(write(out, mdata, n) != n)
error("mount write");
now = time(0);
if(warnarg && (long)(now - lastwarning) > 24*60*60){
syslog(0, "auth", "keyfs starting warnings: %lux %lux",
now, lastwarning);
warning();
lastwarning = now;
}
}
}
int
newkeys(void)
{
Dir *d;
static ulong ftime;
d = dirstat(userkeys);
if(d == nil)
return 0;
if(d->mtime > ftime){
ftime = d->mtime;
free(d);
return 1;
}
free(d);
return 0;
}
void *
emalloc(ulong n)
{
void *p;
if((p = malloc(n)) != nil){
memset(p, 0, n);
return p;
}
error("out of memory");
return nil; /* not reached */
}
char *
estrdup(char *s)
{
char *d;
int n;
n = strlen(s)+1;
d = emalloc(n);
memmove(d, s, n);
return d;
}
void
warning(void)
{
int i;
char buf[64];
snprint(buf, sizeof buf, "-%s", warnarg);
switch(rfork(RFPROC|RFNAMEG|RFNOTEG|RFNOWAIT|RFENVG|RFFDG)){
case 0:
i = open("/sys/log/auth", OWRITE);
if(i >= 0){
dup(i, 2);
seek(2, 0, 2);
close(i);
}
execl("/bin/auth/warning", "warning", warnarg, nil);
error("can't exec warning");
}
}