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sunrpc: don't pass on-stack memory to sg_set_buf
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As of ac4e97a "scatterlist: sg_set_buf() argument must be in linear
mapping", sg_set_buf hits a BUG when make_checksum_v2->xdr_process_buf,
among other callers, passes it memory on the stack.

We only need a scatterlist to pass this to the crypto code, and it seems
like overkill to require kmalloc'd memory just to encrypt a few bytes,
but for now this seems the best fix.

Many of these callers are in the NFS write paths, so we allocate with
GFP_NOFS.  It might be possible to do without allocations here entirely,
but that would probably be a bigger project.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
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J. Bruce Fields committed Oct 26, 2016
1 parent 0cc11a6 commit 2876a34
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Showing 3 changed files with 71 additions and 45 deletions.
13 changes: 9 additions & 4 deletions net/sunrpc/auth_gss/auth_gss.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1616,7 +1616,7 @@ gss_validate(struct rpc_task *task, __be32 *p)
{
struct rpc_cred *cred = task->tk_rqstp->rq_cred;
struct gss_cl_ctx *ctx = gss_cred_get_ctx(cred);
__be32 seq;
__be32 *seq = NULL;
struct kvec iov;
struct xdr_buf verf_buf;
struct xdr_netobj mic;
Expand All @@ -1631,9 +1631,12 @@ gss_validate(struct rpc_task *task, __be32 *p)
goto out_bad;
if (flav != RPC_AUTH_GSS)
goto out_bad;
seq = htonl(task->tk_rqstp->rq_seqno);
iov.iov_base = &seq;
iov.iov_len = sizeof(seq);
seq = kmalloc(4, GFP_NOFS);
if (!seq)
goto out_bad;
*seq = htonl(task->tk_rqstp->rq_seqno);
iov.iov_base = seq;
iov.iov_len = 4;
xdr_buf_from_iov(&iov, &verf_buf);
mic.data = (u8 *)p;
mic.len = len;
Expand All @@ -1653,11 +1656,13 @@ gss_validate(struct rpc_task *task, __be32 *p)
gss_put_ctx(ctx);
dprintk("RPC: %5u %s: gss_verify_mic succeeded.\n",
task->tk_pid, __func__);
kfree(seq);
return p + XDR_QUADLEN(len);
out_bad:
gss_put_ctx(ctx);
dprintk("RPC: %5u %s failed ret %ld.\n", task->tk_pid, __func__,
PTR_ERR(ret));
kfree(seq);
return ret;
}

Expand Down
82 changes: 48 additions & 34 deletions net/sunrpc/auth_gss/gss_krb5_crypto.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -166,8 +166,8 @@ make_checksum_hmac_md5(struct krb5_ctx *kctx, char *header, int hdrlen,
unsigned int usage, struct xdr_netobj *cksumout)
{
struct scatterlist sg[1];
int err;
u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
int err = -1;
u8 *checksumdata;
u8 rc4salt[4];
struct crypto_ahash *md5;
struct crypto_ahash *hmac_md5;
Expand All @@ -187,23 +187,22 @@ make_checksum_hmac_md5(struct krb5_ctx *kctx, char *header, int hdrlen,
return GSS_S_FAILURE;
}

checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_NOFS);
if (!checksumdata)
return GSS_S_FAILURE;

md5 = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(md5))
return GSS_S_FAILURE;
goto out_free_cksum;

hmac_md5 = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0,
CRYPTO_ALG_ASYNC);
if (IS_ERR(hmac_md5)) {
crypto_free_ahash(md5);
return GSS_S_FAILURE;
}
if (IS_ERR(hmac_md5))
goto out_free_md5;

req = ahash_request_alloc(md5, GFP_KERNEL);
if (!req) {
crypto_free_ahash(hmac_md5);
crypto_free_ahash(md5);
return GSS_S_FAILURE;
}
if (!req)
goto out_free_hmac_md5;

ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);

Expand Down Expand Up @@ -232,11 +231,8 @@ make_checksum_hmac_md5(struct krb5_ctx *kctx, char *header, int hdrlen,

ahash_request_free(req);
req = ahash_request_alloc(hmac_md5, GFP_KERNEL);
if (!req) {
crypto_free_ahash(hmac_md5);
crypto_free_ahash(md5);
return GSS_S_FAILURE;
}
if (!req)
goto out_free_hmac_md5;

ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);

Expand All @@ -258,8 +254,12 @@ make_checksum_hmac_md5(struct krb5_ctx *kctx, char *header, int hdrlen,
cksumout->len = kctx->gk5e->cksumlength;
out:
ahash_request_free(req);
crypto_free_ahash(md5);
out_free_hmac_md5:
crypto_free_ahash(hmac_md5);
out_free_md5:
crypto_free_ahash(md5);
out_free_cksum:
kfree(checksumdata);
return err ? GSS_S_FAILURE : 0;
}

Expand All @@ -276,8 +276,8 @@ make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
struct crypto_ahash *tfm;
struct ahash_request *req;
struct scatterlist sg[1];
int err;
u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
int err = -1;
u8 *checksumdata;
unsigned int checksumlen;

if (kctx->gk5e->ctype == CKSUMTYPE_HMAC_MD5_ARCFOUR)
Expand All @@ -291,15 +291,17 @@ make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
return GSS_S_FAILURE;
}

checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_NOFS);
if (checksumdata == NULL)
return GSS_S_FAILURE;

tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(tfm))
return GSS_S_FAILURE;
goto out_free_cksum;

req = ahash_request_alloc(tfm, GFP_KERNEL);
if (!req) {
crypto_free_ahash(tfm);
return GSS_S_FAILURE;
}
if (!req)
goto out_free_ahash;

ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);

Expand Down Expand Up @@ -349,7 +351,10 @@ make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
cksumout->len = kctx->gk5e->cksumlength;
out:
ahash_request_free(req);
out_free_ahash:
crypto_free_ahash(tfm);
out_free_cksum:
kfree(checksumdata);
return err ? GSS_S_FAILURE : 0;
}

Expand All @@ -368,8 +373,8 @@ make_checksum_v2(struct krb5_ctx *kctx, char *header, int hdrlen,
struct crypto_ahash *tfm;
struct ahash_request *req;
struct scatterlist sg[1];
int err;
u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
int err = -1;
u8 *checksumdata;
unsigned int checksumlen;

if (kctx->gk5e->keyed_cksum == 0) {
Expand All @@ -383,16 +388,18 @@ make_checksum_v2(struct krb5_ctx *kctx, char *header, int hdrlen,
return GSS_S_FAILURE;
}

checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_NOFS);
if (!checksumdata)
return GSS_S_FAILURE;

tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(tfm))
return GSS_S_FAILURE;
goto out_free_cksum;
checksumlen = crypto_ahash_digestsize(tfm);

req = ahash_request_alloc(tfm, GFP_KERNEL);
if (!req) {
crypto_free_ahash(tfm);
return GSS_S_FAILURE;
}
if (!req)
goto out_free_ahash;

ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);

Expand Down Expand Up @@ -433,7 +440,10 @@ make_checksum_v2(struct krb5_ctx *kctx, char *header, int hdrlen,
}
out:
ahash_request_free(req);
out_free_ahash:
crypto_free_ahash(tfm);
out_free_cksum:
kfree(checksumdata);
return err ? GSS_S_FAILURE : 0;
}

Expand Down Expand Up @@ -666,14 +676,17 @@ gss_krb5_cts_crypt(struct crypto_skcipher *cipher, struct xdr_buf *buf,
u32 ret;
struct scatterlist sg[1];
SKCIPHER_REQUEST_ON_STACK(req, cipher);
u8 data[GSS_KRB5_MAX_BLOCKSIZE * 2];
u8 *data;
struct page **save_pages;
u32 len = buf->len - offset;

if (len > ARRAY_SIZE(data)) {
if (len > GSS_KRB5_MAX_BLOCKSIZE * 2) {
WARN_ON(0);
return -ENOMEM;
}
data = kmalloc(GSS_KRB5_MAX_BLOCKSIZE * 2, GFP_NOFS);
if (!data)
return -ENOMEM;

/*
* For encryption, we want to read from the cleartext
Expand Down Expand Up @@ -708,6 +721,7 @@ gss_krb5_cts_crypt(struct crypto_skcipher *cipher, struct xdr_buf *buf,
ret = write_bytes_to_xdr_buf(buf, offset, data, len);

out:
kfree(data);
return ret;
}

Expand Down
21 changes: 14 additions & 7 deletions net/sunrpc/auth_gss/svcauth_gss.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -718,30 +718,37 @@ gss_write_null_verf(struct svc_rqst *rqstp)
static int
gss_write_verf(struct svc_rqst *rqstp, struct gss_ctx *ctx_id, u32 seq)
{
__be32 xdr_seq;
__be32 *xdr_seq;
u32 maj_stat;
struct xdr_buf verf_data;
struct xdr_netobj mic;
__be32 *p;
struct kvec iov;
int err = -1;

svc_putnl(rqstp->rq_res.head, RPC_AUTH_GSS);
xdr_seq = htonl(seq);
xdr_seq = kmalloc(4, GFP_KERNEL);
if (!xdr_seq)
return -1;
*xdr_seq = htonl(seq);

iov.iov_base = &xdr_seq;
iov.iov_len = sizeof(xdr_seq);
iov.iov_base = xdr_seq;
iov.iov_len = 4;
xdr_buf_from_iov(&iov, &verf_data);
p = rqstp->rq_res.head->iov_base + rqstp->rq_res.head->iov_len;
mic.data = (u8 *)(p + 1);
maj_stat = gss_get_mic(ctx_id, &verf_data, &mic);
if (maj_stat != GSS_S_COMPLETE)
return -1;
goto out;
*p++ = htonl(mic.len);
memset((u8 *)p + mic.len, 0, round_up_to_quad(mic.len) - mic.len);
p += XDR_QUADLEN(mic.len);
if (!xdr_ressize_check(rqstp, p))
return -1;
return 0;
goto out;
err = 0;
out:
kfree(xdr_seq);
return err;
}

struct gss_domain {
Expand Down

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