linux/net/rxrpc/ar-key.c

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/* RxRPC key management
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* RxRPC keys should have a description of describing their purpose:
* "afs@CAMBRIDGE.REDHAT.COM>
*/
#include <linux/module.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/key-type.h>
#include <linux/crypto.h>
#include <linux/ctype.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include <keys/rxrpc-type.h>
#include <keys/user-type.h>
#include "ar-internal.h"
static int rxrpc_instantiate(struct key *, const void *, size_t);
static int rxrpc_instantiate_s(struct key *, const void *, size_t);
static void rxrpc_destroy(struct key *);
static void rxrpc_destroy_s(struct key *);
static void rxrpc_describe(const struct key *, struct seq_file *);
static long rxrpc_read(const struct key *, char __user *, size_t);
/*
* rxrpc defined keys take an arbitrary string as the description and an
* arbitrary blob of data as the payload
*/
struct key_type key_type_rxrpc = {
.name = "rxrpc",
.instantiate = rxrpc_instantiate,
.match = user_match,
.destroy = rxrpc_destroy,
.describe = rxrpc_describe,
.read = rxrpc_read,
};
EXPORT_SYMBOL(key_type_rxrpc);
/*
* rxrpc server defined keys take "<serviceId>:<securityIndex>" as the
* description and an 8-byte decryption key as the payload
*/
struct key_type key_type_rxrpc_s = {
.name = "rxrpc_s",
.instantiate = rxrpc_instantiate_s,
.match = user_match,
.destroy = rxrpc_destroy_s,
.describe = rxrpc_describe,
};
/*
* parse an RxKAD type XDR format token
* - the caller guarantees we have at least 4 words
*/
static int rxrpc_instantiate_xdr_rxkad(struct key *key, const __be32 *xdr,
unsigned toklen)
{
struct rxrpc_key_token *token, **pptoken;
size_t plen;
u32 tktlen;
int ret;
_enter(",{%x,%x,%x,%x},%u",
ntohl(xdr[0]), ntohl(xdr[1]), ntohl(xdr[2]), ntohl(xdr[3]),
toklen);
if (toklen <= 8 * 4)
return -EKEYREJECTED;
tktlen = ntohl(xdr[7]);
_debug("tktlen: %x", tktlen);
if (tktlen > AFSTOKEN_RK_TIX_MAX)
return -EKEYREJECTED;
if (8 * 4 + tktlen != toklen)
return -EKEYREJECTED;
plen = sizeof(*token) + sizeof(*token->kad) + tktlen;
ret = key_payload_reserve(key, key->datalen + plen);
if (ret < 0)
return ret;
plen -= sizeof(*token);
token = kmalloc(sizeof(*token), GFP_KERNEL);
if (!token)
return -ENOMEM;
token->kad = kmalloc(plen, GFP_KERNEL);
if (!token->kad) {
kfree(token);
return -ENOMEM;
}
token->security_index = RXRPC_SECURITY_RXKAD;
token->kad->ticket_len = tktlen;
token->kad->vice_id = ntohl(xdr[0]);
token->kad->kvno = ntohl(xdr[1]);
token->kad->start = ntohl(xdr[4]);
token->kad->expiry = ntohl(xdr[5]);
token->kad->primary_flag = ntohl(xdr[6]);
memcpy(&token->kad->session_key, &xdr[2], 8);
memcpy(&token->kad->ticket, &xdr[8], tktlen);
_debug("SCIX: %u", token->security_index);
_debug("TLEN: %u", token->kad->ticket_len);
_debug("EXPY: %x", token->kad->expiry);
_debug("KVNO: %u", token->kad->kvno);
_debug("PRIM: %u", token->kad->primary_flag);
_debug("SKEY: %02x%02x%02x%02x%02x%02x%02x%02x",
token->kad->session_key[0], token->kad->session_key[1],
token->kad->session_key[2], token->kad->session_key[3],
token->kad->session_key[4], token->kad->session_key[5],
token->kad->session_key[6], token->kad->session_key[7]);
if (token->kad->ticket_len >= 8)
_debug("TCKT: %02x%02x%02x%02x%02x%02x%02x%02x",
token->kad->ticket[0], token->kad->ticket[1],
token->kad->ticket[2], token->kad->ticket[3],
token->kad->ticket[4], token->kad->ticket[5],
token->kad->ticket[6], token->kad->ticket[7]);
/* count the number of tokens attached */
key->type_data.x[0]++;
/* attach the data */
for (pptoken = (struct rxrpc_key_token **)&key->payload.data;
*pptoken;
pptoken = &(*pptoken)->next)
continue;
*pptoken = token;
if (token->kad->expiry < key->expiry)
key->expiry = token->kad->expiry;
_leave(" = 0");
return 0;
}
static void rxrpc_free_krb5_principal(struct krb5_principal *princ)
{
int loop;
if (princ->name_parts) {
for (loop = princ->n_name_parts - 1; loop >= 0; loop--)
kfree(princ->name_parts[loop]);
kfree(princ->name_parts);
}
kfree(princ->realm);
}
static void rxrpc_free_krb5_tagged(struct krb5_tagged_data *td)
{
kfree(td->data);
}
/*
* free up an RxK5 token
*/
static void rxrpc_rxk5_free(struct rxk5_key *rxk5)
{
int loop;
rxrpc_free_krb5_principal(&rxk5->client);
rxrpc_free_krb5_principal(&rxk5->server);
rxrpc_free_krb5_tagged(&rxk5->session);
if (rxk5->addresses) {
for (loop = rxk5->n_addresses - 1; loop >= 0; loop--)
rxrpc_free_krb5_tagged(&rxk5->addresses[loop]);
kfree(rxk5->addresses);
}
if (rxk5->authdata) {
for (loop = rxk5->n_authdata - 1; loop >= 0; loop--)
rxrpc_free_krb5_tagged(&rxk5->authdata[loop]);
kfree(rxk5->authdata);
}
kfree(rxk5->ticket);
kfree(rxk5->ticket2);
kfree(rxk5);
}
/*
* extract a krb5 principal
*/
static int rxrpc_krb5_decode_principal(struct krb5_principal *princ,
const __be32 **_xdr,
unsigned *_toklen)
{
const __be32 *xdr = *_xdr;
unsigned toklen = *_toklen, n_parts, loop, tmp;
/* there must be at least one name, and at least #names+1 length
* words */
if (toklen <= 12)
return -EINVAL;
_enter(",{%x,%x,%x},%u",
ntohl(xdr[0]), ntohl(xdr[1]), ntohl(xdr[2]), toklen);
n_parts = ntohl(*xdr++);
toklen -= 4;
if (n_parts <= 0 || n_parts > AFSTOKEN_K5_COMPONENTS_MAX)
return -EINVAL;
princ->n_name_parts = n_parts;
if (toklen <= (n_parts + 1) * 4)
return -EINVAL;
princ->name_parts = kcalloc(sizeof(char *), n_parts, GFP_KERNEL);
if (!princ->name_parts)
return -ENOMEM;
for (loop = 0; loop < n_parts; loop++) {
if (toklen < 4)
return -EINVAL;
tmp = ntohl(*xdr++);
toklen -= 4;
if (tmp <= 0 || tmp > AFSTOKEN_STRING_MAX)
return -EINVAL;
if (tmp > toklen)
return -EINVAL;
princ->name_parts[loop] = kmalloc(tmp + 1, GFP_KERNEL);
if (!princ->name_parts[loop])
return -ENOMEM;
memcpy(princ->name_parts[loop], xdr, tmp);
princ->name_parts[loop][tmp] = 0;
tmp = (tmp + 3) & ~3;
toklen -= tmp;
xdr += tmp >> 2;
}
if (toklen < 4)
return -EINVAL;
tmp = ntohl(*xdr++);
toklen -= 4;
if (tmp <= 0 || tmp > AFSTOKEN_K5_REALM_MAX)
return -EINVAL;
if (tmp > toklen)
return -EINVAL;
princ->realm = kmalloc(tmp + 1, GFP_KERNEL);
if (!princ->realm)
return -ENOMEM;
memcpy(princ->realm, xdr, tmp);
princ->realm[tmp] = 0;
tmp = (tmp + 3) & ~3;
toklen -= tmp;
xdr += tmp >> 2;
_debug("%s/...@%s", princ->name_parts[0], princ->realm);
*_xdr = xdr;
*_toklen = toklen;
_leave(" = 0 [toklen=%u]", toklen);
return 0;
}
/*
* extract a piece of krb5 tagged data
*/
static int rxrpc_krb5_decode_tagged_data(struct krb5_tagged_data *td,
size_t max_data_size,
const __be32 **_xdr,
unsigned *_toklen)
{
const __be32 *xdr = *_xdr;
unsigned toklen = *_toklen, len;
/* there must be at least one tag and one length word */
if (toklen <= 8)
return -EINVAL;
_enter(",%zu,{%x,%x},%u",
max_data_size, ntohl(xdr[0]), ntohl(xdr[1]), toklen);
td->tag = ntohl(*xdr++);
len = ntohl(*xdr++);
toklen -= 8;
if (len > max_data_size)
return -EINVAL;
td->data_len = len;
if (len > 0) {
td->data = kmalloc(len, GFP_KERNEL);
if (!td->data)
return -ENOMEM;
memcpy(td->data, xdr, len);
len = (len + 3) & ~3;
toklen -= len;
xdr += len >> 2;
}
_debug("tag %x len %x", td->tag, td->data_len);
*_xdr = xdr;
*_toklen = toklen;
_leave(" = 0 [toklen=%u]", toklen);
return 0;
}
/*
* extract an array of tagged data
*/
static int rxrpc_krb5_decode_tagged_array(struct krb5_tagged_data **_td,
u8 *_n_elem,
u8 max_n_elem,
size_t max_elem_size,
const __be32 **_xdr,
unsigned *_toklen)
{
struct krb5_tagged_data *td;
const __be32 *xdr = *_xdr;
unsigned toklen = *_toklen, n_elem, loop;
int ret;
/* there must be at least one count */
if (toklen < 4)
return -EINVAL;
_enter(",,%u,%zu,{%x},%u",
max_n_elem, max_elem_size, ntohl(xdr[0]), toklen);
n_elem = ntohl(*xdr++);
toklen -= 4;
if (n_elem < 0 || n_elem > max_n_elem)
return -EINVAL;
*_n_elem = n_elem;
if (n_elem > 0) {
if (toklen <= (n_elem + 1) * 4)
return -EINVAL;
_debug("n_elem %d", n_elem);
td = kcalloc(sizeof(struct krb5_tagged_data), n_elem,
GFP_KERNEL);
if (!td)
return -ENOMEM;
*_td = td;
for (loop = 0; loop < n_elem; loop++) {
ret = rxrpc_krb5_decode_tagged_data(&td[loop],
max_elem_size,
&xdr, &toklen);
if (ret < 0)
return ret;
}
}
*_xdr = xdr;
*_toklen = toklen;
_leave(" = 0 [toklen=%u]", toklen);
return 0;
}
/*
* extract a krb5 ticket
*/
static int rxrpc_krb5_decode_ticket(u8 **_ticket, u16 *_tktlen,
const __be32 **_xdr, unsigned *_toklen)
{
const __be32 *xdr = *_xdr;
unsigned toklen = *_toklen, len;
/* there must be at least one length word */
if (toklen <= 4)
return -EINVAL;
_enter(",{%x},%u", ntohl(xdr[0]), toklen);
len = ntohl(*xdr++);
toklen -= 4;
if (len > AFSTOKEN_K5_TIX_MAX)
return -EINVAL;
*_tktlen = len;
_debug("ticket len %u", len);
if (len > 0) {
*_ticket = kmalloc(len, GFP_KERNEL);
if (!*_ticket)
return -ENOMEM;
memcpy(*_ticket, xdr, len);
len = (len + 3) & ~3;
toklen -= len;
xdr += len >> 2;
}
*_xdr = xdr;
*_toklen = toklen;
_leave(" = 0 [toklen=%u]", toklen);
return 0;
}
/*
* parse an RxK5 type XDR format token
* - the caller guarantees we have at least 4 words
*/
static int rxrpc_instantiate_xdr_rxk5(struct key *key, const __be32 *xdr,
unsigned toklen)
{
struct rxrpc_key_token *token, **pptoken;
struct rxk5_key *rxk5;
const __be32 *end_xdr = xdr + (toklen >> 2);
int ret;
_enter(",{%x,%x,%x,%x},%u",
ntohl(xdr[0]), ntohl(xdr[1]), ntohl(xdr[2]), ntohl(xdr[3]),
toklen);
/* reserve some payload space for this subkey - the length of the token
* is a reasonable approximation */
ret = key_payload_reserve(key, key->datalen + toklen);
if (ret < 0)
return ret;
token = kzalloc(sizeof(*token), GFP_KERNEL);
if (!token)
return -ENOMEM;
rxk5 = kzalloc(sizeof(*rxk5), GFP_KERNEL);
if (!rxk5) {
kfree(token);
return -ENOMEM;
}
token->security_index = RXRPC_SECURITY_RXK5;
token->k5 = rxk5;
/* extract the principals */
ret = rxrpc_krb5_decode_principal(&rxk5->client, &xdr, &toklen);
if (ret < 0)
goto error;
ret = rxrpc_krb5_decode_principal(&rxk5->server, &xdr, &toklen);
if (ret < 0)
goto error;
/* extract the session key and the encoding type (the tag field ->
* ENCTYPE_xxx) */
ret = rxrpc_krb5_decode_tagged_data(&rxk5->session, AFSTOKEN_DATA_MAX,
&xdr, &toklen);
if (ret < 0)
goto error;
if (toklen < 4 * 8 + 2 * 4)
goto inval;
rxk5->authtime = be64_to_cpup((const __be64 *) xdr);
xdr += 2;
rxk5->starttime = be64_to_cpup((const __be64 *) xdr);
xdr += 2;
rxk5->endtime = be64_to_cpup((const __be64 *) xdr);
xdr += 2;
rxk5->renew_till = be64_to_cpup((const __be64 *) xdr);
xdr += 2;
rxk5->is_skey = ntohl(*xdr++);
rxk5->flags = ntohl(*xdr++);
toklen -= 4 * 8 + 2 * 4;
_debug("times: a=%llx s=%llx e=%llx rt=%llx",
rxk5->authtime, rxk5->starttime, rxk5->endtime,
rxk5->renew_till);
_debug("is_skey=%x flags=%x", rxk5->is_skey, rxk5->flags);
/* extract the permitted client addresses */
ret = rxrpc_krb5_decode_tagged_array(&rxk5->addresses,
&rxk5->n_addresses,
AFSTOKEN_K5_ADDRESSES_MAX,
AFSTOKEN_DATA_MAX,
&xdr, &toklen);
if (ret < 0)
goto error;
ASSERTCMP((end_xdr - xdr) << 2, ==, toklen);
/* extract the tickets */
ret = rxrpc_krb5_decode_ticket(&rxk5->ticket, &rxk5->ticket_len,
&xdr, &toklen);
if (ret < 0)
goto error;
ret = rxrpc_krb5_decode_ticket(&rxk5->ticket2, &rxk5->ticket2_len,
&xdr, &toklen);
if (ret < 0)
goto error;
ASSERTCMP((end_xdr - xdr) << 2, ==, toklen);
/* extract the typed auth data */
ret = rxrpc_krb5_decode_tagged_array(&rxk5->authdata,
&rxk5->n_authdata,
AFSTOKEN_K5_AUTHDATA_MAX,
AFSTOKEN_BDATALN_MAX,
&xdr, &toklen);
if (ret < 0)
goto error;
ASSERTCMP((end_xdr - xdr) << 2, ==, toklen);
if (toklen != 0)
goto inval;
/* attach the payload to the key */
for (pptoken = (struct rxrpc_key_token **)&key->payload.data;
*pptoken;
pptoken = &(*pptoken)->next)
continue;
*pptoken = token;
if (token->kad->expiry < key->expiry)
key->expiry = token->kad->expiry;
_leave(" = 0");
return 0;
inval:
ret = -EINVAL;
error:
rxrpc_rxk5_free(rxk5);
kfree(token);
_leave(" = %d", ret);
return ret;
}
/*
* attempt to parse the data as the XDR format
* - the caller guarantees we have more than 7 words
*/
static int rxrpc_instantiate_xdr(struct key *key, const void *data, size_t datalen)
{
const __be32 *xdr = data, *token;
const char *cp;
unsigned len, tmp, loop, ntoken, toklen, sec_ix;
int ret;
_enter(",{%x,%x,%x,%x},%zu",
ntohl(xdr[0]), ntohl(xdr[1]), ntohl(xdr[2]), ntohl(xdr[3]),
datalen);
if (datalen > AFSTOKEN_LENGTH_MAX)
goto not_xdr;
/* XDR is an array of __be32's */
if (datalen & 3)
goto not_xdr;
/* the flags should be 0 (the setpag bit must be handled by
* userspace) */
if (ntohl(*xdr++) != 0)
goto not_xdr;
datalen -= 4;
/* check the cell name */
len = ntohl(*xdr++);
if (len < 1 || len > AFSTOKEN_CELL_MAX)
goto not_xdr;
datalen -= 4;
tmp = (len + 3) & ~3;
if (tmp > datalen)
goto not_xdr;
cp = (const char *) xdr;
for (loop = 0; loop < len; loop++)
if (!isprint(cp[loop]))
goto not_xdr;
if (len < tmp)
for (; loop < tmp; loop++)
if (cp[loop])
goto not_xdr;
_debug("cellname: [%u/%u] '%*.*s'",
len, tmp, len, len, (const char *) xdr);
datalen -= tmp;
xdr += tmp >> 2;
/* get the token count */
if (datalen < 12)
goto not_xdr;
ntoken = ntohl(*xdr++);
datalen -= 4;
_debug("ntoken: %x", ntoken);
if (ntoken < 1 || ntoken > AFSTOKEN_MAX)
goto not_xdr;
/* check each token wrapper */
token = xdr;
loop = ntoken;
do {
if (datalen < 8)
goto not_xdr;
toklen = ntohl(*xdr++);
sec_ix = ntohl(*xdr);
datalen -= 4;
_debug("token: [%x/%zx] %x", toklen, datalen, sec_ix);
if (toklen < 20 || toklen > datalen)
goto not_xdr;
datalen -= (toklen + 3) & ~3;
xdr += (toklen + 3) >> 2;
} while (--loop > 0);
_debug("remainder: %zu", datalen);
if (datalen != 0)
goto not_xdr;
/* okay: we're going to assume it's valid XDR format
* - we ignore the cellname, relying on the key to be correctly named
*/
do {
xdr = token;
toklen = ntohl(*xdr++);
token = xdr + ((toklen + 3) >> 2);
sec_ix = ntohl(*xdr++);
toklen -= 4;
_debug("TOKEN type=%u [%p-%p]", sec_ix, xdr, token);
switch (sec_ix) {
case RXRPC_SECURITY_RXKAD:
ret = rxrpc_instantiate_xdr_rxkad(key, xdr, toklen);
if (ret != 0)
goto error;
break;
case RXRPC_SECURITY_RXK5:
ret = rxrpc_instantiate_xdr_rxk5(key, xdr, toklen);
if (ret != 0)
goto error;
break;
default:
ret = -EPROTONOSUPPORT;
goto error;
}
} while (--ntoken > 0);
_leave(" = 0");
return 0;
not_xdr:
_leave(" = -EPROTO");
return -EPROTO;
error:
_leave(" = %d", ret);
return ret;
}
/*
* instantiate an rxrpc defined key
* data should be of the form:
* OFFSET LEN CONTENT
* 0 4 key interface version number
* 4 2 security index (type)
* 6 2 ticket length
* 8 4 key expiry time (time_t)
* 12 4 kvno
* 16 8 session key
* 24 [len] ticket
*
* if no data is provided, then a no-security key is made
*/
static int rxrpc_instantiate(struct key *key, const void *data, size_t datalen)
{
const struct rxrpc_key_data_v1 *v1;
struct rxrpc_key_token *token, **pp;
size_t plen;
u32 kver;
int ret;
_enter("{%x},,%zu", key_serial(key), datalen);
/* handle a no-security key */
if (!data && datalen == 0)
return 0;
/* determine if the XDR payload format is being used */
if (datalen > 7 * 4) {
ret = rxrpc_instantiate_xdr(key, data, datalen);
if (ret != -EPROTO)
return ret;
}
/* get the key interface version number */
ret = -EINVAL;
if (datalen <= 4 || !data)
goto error;
memcpy(&kver, data, sizeof(kver));
data += sizeof(kver);
datalen -= sizeof(kver);
_debug("KEY I/F VERSION: %u", kver);
ret = -EKEYREJECTED;
if (kver != 1)
goto error;
/* deal with a version 1 key */
ret = -EINVAL;
if (datalen < sizeof(*v1))
goto error;
v1 = data;
if (datalen != sizeof(*v1) + v1->ticket_length)
goto error;
_debug("SCIX: %u", v1->security_index);
_debug("TLEN: %u", v1->ticket_length);
_debug("EXPY: %x", v1->expiry);
_debug("KVNO: %u", v1->kvno);
_debug("SKEY: %02x%02x%02x%02x%02x%02x%02x%02x",
v1->session_key[0], v1->session_key[1],
v1->session_key[2], v1->session_key[3],
v1->session_key[4], v1->session_key[5],
v1->session_key[6], v1->session_key[7]);
if (v1->ticket_length >= 8)
_debug("TCKT: %02x%02x%02x%02x%02x%02x%02x%02x",
v1->ticket[0], v1->ticket[1],
v1->ticket[2], v1->ticket[3],
v1->ticket[4], v1->ticket[5],
v1->ticket[6], v1->ticket[7]);
ret = -EPROTONOSUPPORT;
if (v1->security_index != RXRPC_SECURITY_RXKAD)
goto error;
plen = sizeof(*token->kad) + v1->ticket_length;
ret = key_payload_reserve(key, plen + sizeof(*token));
if (ret < 0)
goto error;
ret = -ENOMEM;
token = kmalloc(sizeof(*token), GFP_KERNEL);
if (!token)
goto error;
token->kad = kmalloc(plen, GFP_KERNEL);
if (!token->kad)
goto error_free;
token->security_index = RXRPC_SECURITY_RXKAD;
token->kad->ticket_len = v1->ticket_length;
token->kad->expiry = v1->expiry;
token->kad->kvno = v1->kvno;
memcpy(&token->kad->session_key, &v1->session_key, 8);
memcpy(&token->kad->ticket, v1->ticket, v1->ticket_length);
/* attach the data */
key->type_data.x[0]++;
pp = (struct rxrpc_key_token **)&key->payload.data;
while (*pp)
pp = &(*pp)->next;
*pp = token;
if (token->kad->expiry < key->expiry)
key->expiry = token->kad->expiry;
token = NULL;
ret = 0;
error_free:
kfree(token);
error:
return ret;
}
/*
* instantiate a server secret key
* data should be a pointer to the 8-byte secret key
*/
static int rxrpc_instantiate_s(struct key *key, const void *data,
size_t datalen)
{
struct crypto_blkcipher *ci;
_enter("{%x},,%zu", key_serial(key), datalen);
if (datalen != 8)
return -EINVAL;
memcpy(&key->type_data, data, 8);
ci = crypto_alloc_blkcipher("pcbc(des)", 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(ci)) {
_leave(" = %ld", PTR_ERR(ci));
return PTR_ERR(ci);
}
if (crypto_blkcipher_setkey(ci, data, 8) < 0)
BUG();
key->payload.data = ci;
_leave(" = 0");
return 0;
}
/*
* dispose of the data dangling from the corpse of a rxrpc key
*/
static void rxrpc_destroy(struct key *key)
{
struct rxrpc_key_token *token;
while ((token = key->payload.data)) {
key->payload.data = token->next;
switch (token->security_index) {
case RXRPC_SECURITY_RXKAD:
kfree(token->kad);
break;
case RXRPC_SECURITY_RXK5:
if (token->k5)
rxrpc_rxk5_free(token->k5);
break;
default:
printk(KERN_ERR "Unknown token type %x on rxrpc key\n",
token->security_index);
BUG();
}
kfree(token);
}
}
/*
* dispose of the data dangling from the corpse of a rxrpc key
*/
static void rxrpc_destroy_s(struct key *key)
{
if (key->payload.data) {
crypto_free_blkcipher(key->payload.data);
key->payload.data = NULL;
}
}
/*
* describe the rxrpc key
*/
static void rxrpc_describe(const struct key *key, struct seq_file *m)
{
seq_puts(m, key->description);
}
/*
* grab the security key for a socket
*/
int rxrpc_request_key(struct rxrpc_sock *rx, char __user *optval, int optlen)
{
struct key *key;
char *description;
_enter("");
if (optlen <= 0 || optlen > PAGE_SIZE - 1)
return -EINVAL;
description = kmalloc(optlen + 1, GFP_KERNEL);
if (!description)
return -ENOMEM;
if (copy_from_user(description, optval, optlen)) {
kfree(description);
return -EFAULT;
}
description[optlen] = 0;
key = request_key(&key_type_rxrpc, description, NULL);
if (IS_ERR(key)) {
kfree(description);
_leave(" = %ld", PTR_ERR(key));
return PTR_ERR(key);
}
rx->key = key;
kfree(description);
_leave(" = 0 [key %x]", key->serial);
return 0;
}
/*
* grab the security keyring for a server socket
*/
int rxrpc_server_keyring(struct rxrpc_sock *rx, char __user *optval,
int optlen)
{
struct key *key;
char *description;
_enter("");
if (optlen <= 0 || optlen > PAGE_SIZE - 1)
return -EINVAL;
description = kmalloc(optlen + 1, GFP_KERNEL);
if (!description)
return -ENOMEM;
if (copy_from_user(description, optval, optlen)) {
kfree(description);
return -EFAULT;
}
description[optlen] = 0;
key = request_key(&key_type_keyring, description, NULL);
if (IS_ERR(key)) {
kfree(description);
_leave(" = %ld", PTR_ERR(key));
return PTR_ERR(key);
}
rx->securities = key;
kfree(description);
_leave(" = 0 [key %x]", key->serial);
return 0;
}
/*
* generate a server data key
*/
int rxrpc_get_server_data_key(struct rxrpc_connection *conn,
const void *session_key,
time_t expiry,
u32 kvno)
{
CRED: Inaugurate COW credentials Inaugurate copy-on-write credentials management. This uses RCU to manage the credentials pointer in the task_struct with respect to accesses by other tasks. A process may only modify its own credentials, and so does not need locking to access or modify its own credentials. A mutex (cred_replace_mutex) is added to the task_struct to control the effect of PTRACE_ATTACHED on credential calculations, particularly with respect to execve(). With this patch, the contents of an active credentials struct may not be changed directly; rather a new set of credentials must be prepared, modified and committed using something like the following sequence of events: struct cred *new = prepare_creds(); int ret = blah(new); if (ret < 0) { abort_creds(new); return ret; } return commit_creds(new); There are some exceptions to this rule: the keyrings pointed to by the active credentials may be instantiated - keyrings violate the COW rule as managing COW keyrings is tricky, given that it is possible for a task to directly alter the keys in a keyring in use by another task. To help enforce this, various pointers to sets of credentials, such as those in the task_struct, are declared const. The purpose of this is compile-time discouragement of altering credentials through those pointers. Once a set of credentials has been made public through one of these pointers, it may not be modified, except under special circumstances: (1) Its reference count may incremented and decremented. (2) The keyrings to which it points may be modified, but not replaced. The only safe way to modify anything else is to create a replacement and commit using the functions described in Documentation/credentials.txt (which will be added by a later patch). This patch and the preceding patches have been tested with the LTP SELinux testsuite. This patch makes several logical sets of alteration: (1) execve(). This now prepares and commits credentials in various places in the security code rather than altering the current creds directly. (2) Temporary credential overrides. do_coredump() and sys_faccessat() now prepare their own credentials and temporarily override the ones currently on the acting thread, whilst preventing interference from other threads by holding cred_replace_mutex on the thread being dumped. This will be replaced in a future patch by something that hands down the credentials directly to the functions being called, rather than altering the task's objective credentials. (3) LSM interface. A number of functions have been changed, added or removed: (*) security_capset_check(), ->capset_check() (*) security_capset_set(), ->capset_set() Removed in favour of security_capset(). (*) security_capset(), ->capset() New. This is passed a pointer to the new creds, a pointer to the old creds and the proposed capability sets. It should fill in the new creds or return an error. All pointers, barring the pointer to the new creds, are now const. (*) security_bprm_apply_creds(), ->bprm_apply_creds() Changed; now returns a value, which will cause the process to be killed if it's an error. (*) security_task_alloc(), ->task_alloc_security() Removed in favour of security_prepare_creds(). (*) security_cred_free(), ->cred_free() New. Free security data attached to cred->security. (*) security_prepare_creds(), ->cred_prepare() New. Duplicate any security data attached to cred->security. (*) security_commit_creds(), ->cred_commit() New. Apply any security effects for the upcoming installation of new security by commit_creds(). (*) security_task_post_setuid(), ->task_post_setuid() Removed in favour of security_task_fix_setuid(). (*) security_task_fix_setuid(), ->task_fix_setuid() Fix up the proposed new credentials for setuid(). This is used by cap_set_fix_setuid() to implicitly adjust capabilities in line with setuid() changes. Changes are made to the new credentials, rather than the task itself as in security_task_post_setuid(). (*) security_task_reparent_to_init(), ->task_reparent_to_init() Removed. Instead the task being reparented to init is referred directly to init's credentials. NOTE! This results in the loss of some state: SELinux's osid no longer records the sid of the thread that forked it. (*) security_key_alloc(), ->key_alloc() (*) security_key_permission(), ->key_permission() Changed. These now take cred pointers rather than task pointers to refer to the security context. (4) sys_capset(). This has been simplified and uses less locking. The LSM functions it calls have been merged. (5) reparent_to_kthreadd(). This gives the current thread the same credentials as init by simply using commit_thread() to point that way. (6) __sigqueue_alloc() and switch_uid() __sigqueue_alloc() can't stop the target task from changing its creds beneath it, so this function gets a reference to the currently applicable user_struct which it then passes into the sigqueue struct it returns if successful. switch_uid() is now called from commit_creds(), and possibly should be folded into that. commit_creds() should take care of protecting __sigqueue_alloc(). (7) [sg]et[ug]id() and co and [sg]et_current_groups. The set functions now all use prepare_creds(), commit_creds() and abort_creds() to build and check a new set of credentials before applying it. security_task_set[ug]id() is called inside the prepared section. This guarantees that nothing else will affect the creds until we've finished. The calling of set_dumpable() has been moved into commit_creds(). Much of the functionality of set_user() has been moved into commit_creds(). The get functions all simply access the data directly. (8) security_task_prctl() and cap_task_prctl(). security_task_prctl() has been modified to return -ENOSYS if it doesn't want to handle a function, or otherwise return the return value directly rather than through an argument. Additionally, cap_task_prctl() now prepares a new set of credentials, even if it doesn't end up using it. (9) Keyrings. A number of changes have been made to the keyrings code: (a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have all been dropped and built in to the credentials functions directly. They may want separating out again later. (b) key_alloc() and search_process_keyrings() now take a cred pointer rather than a task pointer to specify the security context. (c) copy_creds() gives a new thread within the same thread group a new thread keyring if its parent had one, otherwise it discards the thread keyring. (d) The authorisation key now points directly to the credentials to extend the search into rather pointing to the task that carries them. (e) Installing thread, process or session keyrings causes a new set of credentials to be created, even though it's not strictly necessary for process or session keyrings (they're shared). (10) Usermode helper. The usermode helper code now carries a cred struct pointer in its subprocess_info struct instead of a new session keyring pointer. This set of credentials is derived from init_cred and installed on the new process after it has been cloned. call_usermodehelper_setup() allocates the new credentials and call_usermodehelper_freeinfo() discards them if they haven't been used. A special cred function (prepare_usermodeinfo_creds()) is provided specifically for call_usermodehelper_setup() to call. call_usermodehelper_setkeys() adjusts the credentials to sport the supplied keyring as the new session keyring. (11) SELinux. SELinux has a number of changes, in addition to those to support the LSM interface changes mentioned above: (a) selinux_setprocattr() no longer does its check for whether the current ptracer can access processes with the new SID inside the lock that covers getting the ptracer's SID. Whilst this lock ensures that the check is done with the ptracer pinned, the result is only valid until the lock is released, so there's no point doing it inside the lock. (12) is_single_threaded(). This function has been extracted from selinux_setprocattr() and put into a file of its own in the lib/ directory as join_session_keyring() now wants to use it too. The code in SELinux just checked to see whether a task shared mm_structs with other tasks (CLONE_VM), but that isn't good enough. We really want to know if they're part of the same thread group (CLONE_THREAD). (13) nfsd. The NFS server daemon now has to use the COW credentials to set the credentials it is going to use. It really needs to pass the credentials down to the functions it calls, but it can't do that until other patches in this series have been applied. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: James Morris <jmorris@namei.org> Signed-off-by: James Morris <jmorris@namei.org>
2008-11-13 23:39:23 +00:00
const struct cred *cred = current_cred();
struct key *key;
int ret;
struct {
u32 kver;
struct rxrpc_key_data_v1 v1;
} data;
_enter("");
CRED: Inaugurate COW credentials Inaugurate copy-on-write credentials management. This uses RCU to manage the credentials pointer in the task_struct with respect to accesses by other tasks. A process may only modify its own credentials, and so does not need locking to access or modify its own credentials. A mutex (cred_replace_mutex) is added to the task_struct to control the effect of PTRACE_ATTACHED on credential calculations, particularly with respect to execve(). With this patch, the contents of an active credentials struct may not be changed directly; rather a new set of credentials must be prepared, modified and committed using something like the following sequence of events: struct cred *new = prepare_creds(); int ret = blah(new); if (ret < 0) { abort_creds(new); return ret; } return commit_creds(new); There are some exceptions to this rule: the keyrings pointed to by the active credentials may be instantiated - keyrings violate the COW rule as managing COW keyrings is tricky, given that it is possible for a task to directly alter the keys in a keyring in use by another task. To help enforce this, various pointers to sets of credentials, such as those in the task_struct, are declared const. The purpose of this is compile-time discouragement of altering credentials through those pointers. Once a set of credentials has been made public through one of these pointers, it may not be modified, except under special circumstances: (1) Its reference count may incremented and decremented. (2) The keyrings to which it points may be modified, but not replaced. The only safe way to modify anything else is to create a replacement and commit using the functions described in Documentation/credentials.txt (which will be added by a later patch). This patch and the preceding patches have been tested with the LTP SELinux testsuite. This patch makes several logical sets of alteration: (1) execve(). This now prepares and commits credentials in various places in the security code rather than altering the current creds directly. (2) Temporary credential overrides. do_coredump() and sys_faccessat() now prepare their own credentials and temporarily override the ones currently on the acting thread, whilst preventing interference from other threads by holding cred_replace_mutex on the thread being dumped. This will be replaced in a future patch by something that hands down the credentials directly to the functions being called, rather than altering the task's objective credentials. (3) LSM interface. A number of functions have been changed, added or removed: (*) security_capset_check(), ->capset_check() (*) security_capset_set(), ->capset_set() Removed in favour of security_capset(). (*) security_capset(), ->capset() New. This is passed a pointer to the new creds, a pointer to the old creds and the proposed capability sets. It should fill in the new creds or return an error. All pointers, barring the pointer to the new creds, are now const. (*) security_bprm_apply_creds(), ->bprm_apply_creds() Changed; now returns a value, which will cause the process to be killed if it's an error. (*) security_task_alloc(), ->task_alloc_security() Removed in favour of security_prepare_creds(). (*) security_cred_free(), ->cred_free() New. Free security data attached to cred->security. (*) security_prepare_creds(), ->cred_prepare() New. Duplicate any security data attached to cred->security. (*) security_commit_creds(), ->cred_commit() New. Apply any security effects for the upcoming installation of new security by commit_creds(). (*) security_task_post_setuid(), ->task_post_setuid() Removed in favour of security_task_fix_setuid(). (*) security_task_fix_setuid(), ->task_fix_setuid() Fix up the proposed new credentials for setuid(). This is used by cap_set_fix_setuid() to implicitly adjust capabilities in line with setuid() changes. Changes are made to the new credentials, rather than the task itself as in security_task_post_setuid(). (*) security_task_reparent_to_init(), ->task_reparent_to_init() Removed. Instead the task being reparented to init is referred directly to init's credentials. NOTE! This results in the loss of some state: SELinux's osid no longer records the sid of the thread that forked it. (*) security_key_alloc(), ->key_alloc() (*) security_key_permission(), ->key_permission() Changed. These now take cred pointers rather than task pointers to refer to the security context. (4) sys_capset(). This has been simplified and uses less locking. The LSM functions it calls have been merged. (5) reparent_to_kthreadd(). This gives the current thread the same credentials as init by simply using commit_thread() to point that way. (6) __sigqueue_alloc() and switch_uid() __sigqueue_alloc() can't stop the target task from changing its creds beneath it, so this function gets a reference to the currently applicable user_struct which it then passes into the sigqueue struct it returns if successful. switch_uid() is now called from commit_creds(), and possibly should be folded into that. commit_creds() should take care of protecting __sigqueue_alloc(). (7) [sg]et[ug]id() and co and [sg]et_current_groups. The set functions now all use prepare_creds(), commit_creds() and abort_creds() to build and check a new set of credentials before applying it. security_task_set[ug]id() is called inside the prepared section. This guarantees that nothing else will affect the creds until we've finished. The calling of set_dumpable() has been moved into commit_creds(). Much of the functionality of set_user() has been moved into commit_creds(). The get functions all simply access the data directly. (8) security_task_prctl() and cap_task_prctl(). security_task_prctl() has been modified to return -ENOSYS if it doesn't want to handle a function, or otherwise return the return value directly rather than through an argument. Additionally, cap_task_prctl() now prepares a new set of credentials, even if it doesn't end up using it. (9) Keyrings. A number of changes have been made to the keyrings code: (a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have all been dropped and built in to the credentials functions directly. They may want separating out again later. (b) key_alloc() and search_process_keyrings() now take a cred pointer rather than a task pointer to specify the security context. (c) copy_creds() gives a new thread within the same thread group a new thread keyring if its parent had one, otherwise it discards the thread keyring. (d) The authorisation key now points directly to the credentials to extend the search into rather pointing to the task that carries them. (e) Installing thread, process or session keyrings causes a new set of credentials to be created, even though it's not strictly necessary for process or session keyrings (they're shared). (10) Usermode helper. The usermode helper code now carries a cred struct pointer in its subprocess_info struct instead of a new session keyring pointer. This set of credentials is derived from init_cred and installed on the new process after it has been cloned. call_usermodehelper_setup() allocates the new credentials and call_usermodehelper_freeinfo() discards them if they haven't been used. A special cred function (prepare_usermodeinfo_creds()) is provided specifically for call_usermodehelper_setup() to call. call_usermodehelper_setkeys() adjusts the credentials to sport the supplied keyring as the new session keyring. (11) SELinux. SELinux has a number of changes, in addition to those to support the LSM interface changes mentioned above: (a) selinux_setprocattr() no longer does its check for whether the current ptracer can access processes with the new SID inside the lock that covers getting the ptracer's SID. Whilst this lock ensures that the check is done with the ptracer pinned, the result is only valid until the lock is released, so there's no point doing it inside the lock. (12) is_single_threaded(). This function has been extracted from selinux_setprocattr() and put into a file of its own in the lib/ directory as join_session_keyring() now wants to use it too. The code in SELinux just checked to see whether a task shared mm_structs with other tasks (CLONE_VM), but that isn't good enough. We really want to know if they're part of the same thread group (CLONE_THREAD). (13) nfsd. The NFS server daemon now has to use the COW credentials to set the credentials it is going to use. It really needs to pass the credentials down to the functions it calls, but it can't do that until other patches in this series have been applied. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: James Morris <jmorris@namei.org> Signed-off-by: James Morris <jmorris@namei.org>
2008-11-13 23:39:23 +00:00
key = key_alloc(&key_type_rxrpc, "x", 0, 0, cred, 0,
KEY_ALLOC_NOT_IN_QUOTA);
if (IS_ERR(key)) {
_leave(" = -ENOMEM [alloc %ld]", PTR_ERR(key));
return -ENOMEM;
}
_debug("key %d", key_serial(key));
data.kver = 1;
data.v1.security_index = RXRPC_SECURITY_RXKAD;
data.v1.ticket_length = 0;
data.v1.expiry = expiry;
data.v1.kvno = 0;
memcpy(&data.v1.session_key, session_key, sizeof(data.v1.session_key));
ret = key_instantiate_and_link(key, &data, sizeof(data), NULL, NULL);
if (ret < 0)
goto error;
conn->key = key;
_leave(" = 0 [%d]", key_serial(key));
return 0;
error:
key_revoke(key);
key_put(key);
_leave(" = -ENOMEM [ins %d]", ret);
return -ENOMEM;
}
EXPORT_SYMBOL(rxrpc_get_server_data_key);
/**
* rxrpc_get_null_key - Generate a null RxRPC key
* @keyname: The name to give the key.
*
* Generate a null RxRPC key that can be used to indicate anonymous security is
* required for a particular domain.
*/
struct key *rxrpc_get_null_key(const char *keyname)
{
CRED: Inaugurate COW credentials Inaugurate copy-on-write credentials management. This uses RCU to manage the credentials pointer in the task_struct with respect to accesses by other tasks. A process may only modify its own credentials, and so does not need locking to access or modify its own credentials. A mutex (cred_replace_mutex) is added to the task_struct to control the effect of PTRACE_ATTACHED on credential calculations, particularly with respect to execve(). With this patch, the contents of an active credentials struct may not be changed directly; rather a new set of credentials must be prepared, modified and committed using something like the following sequence of events: struct cred *new = prepare_creds(); int ret = blah(new); if (ret < 0) { abort_creds(new); return ret; } return commit_creds(new); There are some exceptions to this rule: the keyrings pointed to by the active credentials may be instantiated - keyrings violate the COW rule as managing COW keyrings is tricky, given that it is possible for a task to directly alter the keys in a keyring in use by another task. To help enforce this, various pointers to sets of credentials, such as those in the task_struct, are declared const. The purpose of this is compile-time discouragement of altering credentials through those pointers. Once a set of credentials has been made public through one of these pointers, it may not be modified, except under special circumstances: (1) Its reference count may incremented and decremented. (2) The keyrings to which it points may be modified, but not replaced. The only safe way to modify anything else is to create a replacement and commit using the functions described in Documentation/credentials.txt (which will be added by a later patch). This patch and the preceding patches have been tested with the LTP SELinux testsuite. This patch makes several logical sets of alteration: (1) execve(). This now prepares and commits credentials in various places in the security code rather than altering the current creds directly. (2) Temporary credential overrides. do_coredump() and sys_faccessat() now prepare their own credentials and temporarily override the ones currently on the acting thread, whilst preventing interference from other threads by holding cred_replace_mutex on the thread being dumped. This will be replaced in a future patch by something that hands down the credentials directly to the functions being called, rather than altering the task's objective credentials. (3) LSM interface. A number of functions have been changed, added or removed: (*) security_capset_check(), ->capset_check() (*) security_capset_set(), ->capset_set() Removed in favour of security_capset(). (*) security_capset(), ->capset() New. This is passed a pointer to the new creds, a pointer to the old creds and the proposed capability sets. It should fill in the new creds or return an error. All pointers, barring the pointer to the new creds, are now const. (*) security_bprm_apply_creds(), ->bprm_apply_creds() Changed; now returns a value, which will cause the process to be killed if it's an error. (*) security_task_alloc(), ->task_alloc_security() Removed in favour of security_prepare_creds(). (*) security_cred_free(), ->cred_free() New. Free security data attached to cred->security. (*) security_prepare_creds(), ->cred_prepare() New. Duplicate any security data attached to cred->security. (*) security_commit_creds(), ->cred_commit() New. Apply any security effects for the upcoming installation of new security by commit_creds(). (*) security_task_post_setuid(), ->task_post_setuid() Removed in favour of security_task_fix_setuid(). (*) security_task_fix_setuid(), ->task_fix_setuid() Fix up the proposed new credentials for setuid(). This is used by cap_set_fix_setuid() to implicitly adjust capabilities in line with setuid() changes. Changes are made to the new credentials, rather than the task itself as in security_task_post_setuid(). (*) security_task_reparent_to_init(), ->task_reparent_to_init() Removed. Instead the task being reparented to init is referred directly to init's credentials. NOTE! This results in the loss of some state: SELinux's osid no longer records the sid of the thread that forked it. (*) security_key_alloc(), ->key_alloc() (*) security_key_permission(), ->key_permission() Changed. These now take cred pointers rather than task pointers to refer to the security context. (4) sys_capset(). This has been simplified and uses less locking. The LSM functions it calls have been merged. (5) reparent_to_kthreadd(). This gives the current thread the same credentials as init by simply using commit_thread() to point that way. (6) __sigqueue_alloc() and switch_uid() __sigqueue_alloc() can't stop the target task from changing its creds beneath it, so this function gets a reference to the currently applicable user_struct which it then passes into the sigqueue struct it returns if successful. switch_uid() is now called from commit_creds(), and possibly should be folded into that. commit_creds() should take care of protecting __sigqueue_alloc(). (7) [sg]et[ug]id() and co and [sg]et_current_groups. The set functions now all use prepare_creds(), commit_creds() and abort_creds() to build and check a new set of credentials before applying it. security_task_set[ug]id() is called inside the prepared section. This guarantees that nothing else will affect the creds until we've finished. The calling of set_dumpable() has been moved into commit_creds(). Much of the functionality of set_user() has been moved into commit_creds(). The get functions all simply access the data directly. (8) security_task_prctl() and cap_task_prctl(). security_task_prctl() has been modified to return -ENOSYS if it doesn't want to handle a function, or otherwise return the return value directly rather than through an argument. Additionally, cap_task_prctl() now prepares a new set of credentials, even if it doesn't end up using it. (9) Keyrings. A number of changes have been made to the keyrings code: (a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have all been dropped and built in to the credentials functions directly. They may want separating out again later. (b) key_alloc() and search_process_keyrings() now take a cred pointer rather than a task pointer to specify the security context. (c) copy_creds() gives a new thread within the same thread group a new thread keyring if its parent had one, otherwise it discards the thread keyring. (d) The authorisation key now points directly to the credentials to extend the search into rather pointing to the task that carries them. (e) Installing thread, process or session keyrings causes a new set of credentials to be created, even though it's not strictly necessary for process or session keyrings (they're shared). (10) Usermode helper. The usermode helper code now carries a cred struct pointer in its subprocess_info struct instead of a new session keyring pointer. This set of credentials is derived from init_cred and installed on the new process after it has been cloned. call_usermodehelper_setup() allocates the new credentials and call_usermodehelper_freeinfo() discards them if they haven't been used. A special cred function (prepare_usermodeinfo_creds()) is provided specifically for call_usermodehelper_setup() to call. call_usermodehelper_setkeys() adjusts the credentials to sport the supplied keyring as the new session keyring. (11) SELinux. SELinux has a number of changes, in addition to those to support the LSM interface changes mentioned above: (a) selinux_setprocattr() no longer does its check for whether the current ptracer can access processes with the new SID inside the lock that covers getting the ptracer's SID. Whilst this lock ensures that the check is done with the ptracer pinned, the result is only valid until the lock is released, so there's no point doing it inside the lock. (12) is_single_threaded(). This function has been extracted from selinux_setprocattr() and put into a file of its own in the lib/ directory as join_session_keyring() now wants to use it too. The code in SELinux just checked to see whether a task shared mm_structs with other tasks (CLONE_VM), but that isn't good enough. We really want to know if they're part of the same thread group (CLONE_THREAD). (13) nfsd. The NFS server daemon now has to use the COW credentials to set the credentials it is going to use. It really needs to pass the credentials down to the functions it calls, but it can't do that until other patches in this series have been applied. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: James Morris <jmorris@namei.org> Signed-off-by: James Morris <jmorris@namei.org>
2008-11-13 23:39:23 +00:00
const struct cred *cred = current_cred();
struct key *key;
int ret;
CRED: Inaugurate COW credentials Inaugurate copy-on-write credentials management. This uses RCU to manage the credentials pointer in the task_struct with respect to accesses by other tasks. A process may only modify its own credentials, and so does not need locking to access or modify its own credentials. A mutex (cred_replace_mutex) is added to the task_struct to control the effect of PTRACE_ATTACHED on credential calculations, particularly with respect to execve(). With this patch, the contents of an active credentials struct may not be changed directly; rather a new set of credentials must be prepared, modified and committed using something like the following sequence of events: struct cred *new = prepare_creds(); int ret = blah(new); if (ret < 0) { abort_creds(new); return ret; } return commit_creds(new); There are some exceptions to this rule: the keyrings pointed to by the active credentials may be instantiated - keyrings violate the COW rule as managing COW keyrings is tricky, given that it is possible for a task to directly alter the keys in a keyring in use by another task. To help enforce this, various pointers to sets of credentials, such as those in the task_struct, are declared const. The purpose of this is compile-time discouragement of altering credentials through those pointers. Once a set of credentials has been made public through one of these pointers, it may not be modified, except under special circumstances: (1) Its reference count may incremented and decremented. (2) The keyrings to which it points may be modified, but not replaced. The only safe way to modify anything else is to create a replacement and commit using the functions described in Documentation/credentials.txt (which will be added by a later patch). This patch and the preceding patches have been tested with the LTP SELinux testsuite. This patch makes several logical sets of alteration: (1) execve(). This now prepares and commits credentials in various places in the security code rather than altering the current creds directly. (2) Temporary credential overrides. do_coredump() and sys_faccessat() now prepare their own credentials and temporarily override the ones currently on the acting thread, whilst preventing interference from other threads by holding cred_replace_mutex on the thread being dumped. This will be replaced in a future patch by something that hands down the credentials directly to the functions being called, rather than altering the task's objective credentials. (3) LSM interface. A number of functions have been changed, added or removed: (*) security_capset_check(), ->capset_check() (*) security_capset_set(), ->capset_set() Removed in favour of security_capset(). (*) security_capset(), ->capset() New. This is passed a pointer to the new creds, a pointer to the old creds and the proposed capability sets. It should fill in the new creds or return an error. All pointers, barring the pointer to the new creds, are now const. (*) security_bprm_apply_creds(), ->bprm_apply_creds() Changed; now returns a value, which will cause the process to be killed if it's an error. (*) security_task_alloc(), ->task_alloc_security() Removed in favour of security_prepare_creds(). (*) security_cred_free(), ->cred_free() New. Free security data attached to cred->security. (*) security_prepare_creds(), ->cred_prepare() New. Duplicate any security data attached to cred->security. (*) security_commit_creds(), ->cred_commit() New. Apply any security effects for the upcoming installation of new security by commit_creds(). (*) security_task_post_setuid(), ->task_post_setuid() Removed in favour of security_task_fix_setuid(). (*) security_task_fix_setuid(), ->task_fix_setuid() Fix up the proposed new credentials for setuid(). This is used by cap_set_fix_setuid() to implicitly adjust capabilities in line with setuid() changes. Changes are made to the new credentials, rather than the task itself as in security_task_post_setuid(). (*) security_task_reparent_to_init(), ->task_reparent_to_init() Removed. Instead the task being reparented to init is referred directly to init's credentials. NOTE! This results in the loss of some state: SELinux's osid no longer records the sid of the thread that forked it. (*) security_key_alloc(), ->key_alloc() (*) security_key_permission(), ->key_permission() Changed. These now take cred pointers rather than task pointers to refer to the security context. (4) sys_capset(). This has been simplified and uses less locking. The LSM functions it calls have been merged. (5) reparent_to_kthreadd(). This gives the current thread the same credentials as init by simply using commit_thread() to point that way. (6) __sigqueue_alloc() and switch_uid() __sigqueue_alloc() can't stop the target task from changing its creds beneath it, so this function gets a reference to the currently applicable user_struct which it then passes into the sigqueue struct it returns if successful. switch_uid() is now called from commit_creds(), and possibly should be folded into that. commit_creds() should take care of protecting __sigqueue_alloc(). (7) [sg]et[ug]id() and co and [sg]et_current_groups. The set functions now all use prepare_creds(), commit_creds() and abort_creds() to build and check a new set of credentials before applying it. security_task_set[ug]id() is called inside the prepared section. This guarantees that nothing else will affect the creds until we've finished. The calling of set_dumpable() has been moved into commit_creds(). Much of the functionality of set_user() has been moved into commit_creds(). The get functions all simply access the data directly. (8) security_task_prctl() and cap_task_prctl(). security_task_prctl() has been modified to return -ENOSYS if it doesn't want to handle a function, or otherwise return the return value directly rather than through an argument. Additionally, cap_task_prctl() now prepares a new set of credentials, even if it doesn't end up using it. (9) Keyrings. A number of changes have been made to the keyrings code: (a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have all been dropped and built in to the credentials functions directly. They may want separating out again later. (b) key_alloc() and search_process_keyrings() now take a cred pointer rather than a task pointer to specify the security context. (c) copy_creds() gives a new thread within the same thread group a new thread keyring if its parent had one, otherwise it discards the thread keyring. (d) The authorisation key now points directly to the credentials to extend the search into rather pointing to the task that carries them. (e) Installing thread, process or session keyrings causes a new set of credentials to be created, even though it's not strictly necessary for process or session keyrings (they're shared). (10) Usermode helper. The usermode helper code now carries a cred struct pointer in its subprocess_info struct instead of a new session keyring pointer. This set of credentials is derived from init_cred and installed on the new process after it has been cloned. call_usermodehelper_setup() allocates the new credentials and call_usermodehelper_freeinfo() discards them if they haven't been used. A special cred function (prepare_usermodeinfo_creds()) is provided specifically for call_usermodehelper_setup() to call. call_usermodehelper_setkeys() adjusts the credentials to sport the supplied keyring as the new session keyring. (11) SELinux. SELinux has a number of changes, in addition to those to support the LSM interface changes mentioned above: (a) selinux_setprocattr() no longer does its check for whether the current ptracer can access processes with the new SID inside the lock that covers getting the ptracer's SID. Whilst this lock ensures that the check is done with the ptracer pinned, the result is only valid until the lock is released, so there's no point doing it inside the lock. (12) is_single_threaded(). This function has been extracted from selinux_setprocattr() and put into a file of its own in the lib/ directory as join_session_keyring() now wants to use it too. The code in SELinux just checked to see whether a task shared mm_structs with other tasks (CLONE_VM), but that isn't good enough. We really want to know if they're part of the same thread group (CLONE_THREAD). (13) nfsd. The NFS server daemon now has to use the COW credentials to set the credentials it is going to use. It really needs to pass the credentials down to the functions it calls, but it can't do that until other patches in this series have been applied. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: James Morris <jmorris@namei.org> Signed-off-by: James Morris <jmorris@namei.org>
2008-11-13 23:39:23 +00:00
key = key_alloc(&key_type_rxrpc, keyname, 0, 0, cred,
KEY_POS_SEARCH, KEY_ALLOC_NOT_IN_QUOTA);
if (IS_ERR(key))
return key;
ret = key_instantiate_and_link(key, NULL, 0, NULL, NULL);
if (ret < 0) {
key_revoke(key);
key_put(key);
return ERR_PTR(ret);
}
return key;
}
EXPORT_SYMBOL(rxrpc_get_null_key);
/*
* read the contents of an rxrpc key
* - this returns the result in XDR form
*/
static long rxrpc_read(const struct key *key,
char __user *buffer, size_t buflen)
{
const struct rxrpc_key_token *token;
const struct krb5_principal *princ;
size_t size;
__be32 __user *xdr, *oldxdr;
u32 cnlen, toksize, ntoks, tok, zero;
u16 toksizes[AFSTOKEN_MAX];
int loop;
_enter("");
/* we don't know what form we should return non-AFS keys in */
if (memcmp(key->description, "afs@", 4) != 0)
return -EOPNOTSUPP;
cnlen = strlen(key->description + 4);
#define RND(X) (((X) + 3) & ~3)
/* AFS keys we return in XDR form, so we need to work out the size of
* the XDR */
size = 2 * 4; /* flags, cellname len */
size += RND(cnlen); /* cellname */
size += 1 * 4; /* token count */
ntoks = 0;
for (token = key->payload.data; token; token = token->next) {
toksize = 4; /* sec index */
switch (token->security_index) {
case RXRPC_SECURITY_RXKAD:
toksize += 8 * 4; /* viceid, kvno, key*2, begin,
* end, primary, tktlen */
toksize += RND(token->kad->ticket_len);
break;
case RXRPC_SECURITY_RXK5:
princ = &token->k5->client;
toksize += 4 + princ->n_name_parts * 4;
for (loop = 0; loop < princ->n_name_parts; loop++)
toksize += RND(strlen(princ->name_parts[loop]));
toksize += 4 + RND(strlen(princ->realm));
princ = &token->k5->server;
toksize += 4 + princ->n_name_parts * 4;
for (loop = 0; loop < princ->n_name_parts; loop++)
toksize += RND(strlen(princ->name_parts[loop]));
toksize += 4 + RND(strlen(princ->realm));
toksize += 8 + RND(token->k5->session.data_len);
toksize += 4 * 8 + 2 * 4;
toksize += 4 + token->k5->n_addresses * 8;
for (loop = 0; loop < token->k5->n_addresses; loop++)
toksize += RND(token->k5->addresses[loop].data_len);
toksize += 4 + RND(token->k5->ticket_len);
toksize += 4 + RND(token->k5->ticket2_len);
toksize += 4 + token->k5->n_authdata * 8;
for (loop = 0; loop < token->k5->n_authdata; loop++)
toksize += RND(token->k5->authdata[loop].data_len);
break;
default: /* we have a ticket we can't encode */
BUG();
continue;
}
_debug("token[%u]: toksize=%u", ntoks, toksize);
ASSERTCMP(toksize, <=, AFSTOKEN_LENGTH_MAX);
toksizes[ntoks++] = toksize;
size += toksize + 4; /* each token has a length word */
}
#undef RND
if (!buffer || buflen < size)
return size;
xdr = (__be32 __user *) buffer;
zero = 0;
#define ENCODE(x) \
do { \
__be32 y = htonl(x); \
if (put_user(y, xdr++) < 0) \
goto fault; \
} while(0)
#define ENCODE_DATA(l, s) \
do { \
u32 _l = (l); \
ENCODE(l); \
if (copy_to_user(xdr, (s), _l) != 0) \
goto fault; \
if (_l & 3 && \
copy_to_user((u8 *)xdr + _l, &zero, 4 - (_l & 3)) != 0) \
goto fault; \
xdr += (_l + 3) >> 2; \
} while(0)
#define ENCODE64(x) \
do { \
__be64 y = cpu_to_be64(x); \
if (copy_to_user(xdr, &y, 8) != 0) \
goto fault; \
xdr += 8 >> 2; \
} while(0)
#define ENCODE_STR(s) \
do { \
const char *_s = (s); \
ENCODE_DATA(strlen(_s), _s); \
} while(0)
ENCODE(0); /* flags */
ENCODE_DATA(cnlen, key->description + 4); /* cellname */
ENCODE(ntoks);
tok = 0;
for (token = key->payload.data; token; token = token->next) {
toksize = toksizes[tok++];
ENCODE(toksize);
oldxdr = xdr;
ENCODE(token->security_index);
switch (token->security_index) {
case RXRPC_SECURITY_RXKAD:
ENCODE(token->kad->vice_id);
ENCODE(token->kad->kvno);
ENCODE_DATA(8, token->kad->session_key);
ENCODE(token->kad->start);
ENCODE(token->kad->expiry);
ENCODE(token->kad->primary_flag);
ENCODE_DATA(token->kad->ticket_len, token->kad->ticket);
break;
case RXRPC_SECURITY_RXK5:
princ = &token->k5->client;
ENCODE(princ->n_name_parts);
for (loop = 0; loop < princ->n_name_parts; loop++)
ENCODE_STR(princ->name_parts[loop]);
ENCODE_STR(princ->realm);
princ = &token->k5->server;
ENCODE(princ->n_name_parts);
for (loop = 0; loop < princ->n_name_parts; loop++)
ENCODE_STR(princ->name_parts[loop]);
ENCODE_STR(princ->realm);
ENCODE(token->k5->session.tag);
ENCODE_DATA(token->k5->session.data_len,
token->k5->session.data);
ENCODE64(token->k5->authtime);
ENCODE64(token->k5->starttime);
ENCODE64(token->k5->endtime);
ENCODE64(token->k5->renew_till);
ENCODE(token->k5->is_skey);
ENCODE(token->k5->flags);
ENCODE(token->k5->n_addresses);
for (loop = 0; loop < token->k5->n_addresses; loop++) {
ENCODE(token->k5->addresses[loop].tag);
ENCODE_DATA(token->k5->addresses[loop].data_len,
token->k5->addresses[loop].data);
}
ENCODE_DATA(token->k5->ticket_len, token->k5->ticket);
ENCODE_DATA(token->k5->ticket2_len, token->k5->ticket2);
ENCODE(token->k5->n_authdata);
for (loop = 0; loop < token->k5->n_authdata; loop++) {
ENCODE(token->k5->authdata[loop].tag);
ENCODE_DATA(token->k5->authdata[loop].data_len,
token->k5->authdata[loop].data);
}
break;
default:
BUG();
break;
}
ASSERTCMP((unsigned long)xdr - (unsigned long)oldxdr, ==,
toksize);
}
#undef ENCODE_STR
#undef ENCODE_DATA
#undef ENCODE64
#undef ENCODE
ASSERTCMP(tok, ==, ntoks);
ASSERTCMP((char __user *) xdr - buffer, ==, size);
_leave(" = %zu", size);
return size;
fault:
_leave(" = -EFAULT");
return -EFAULT;
}