diff options
| -rw-r--r-- | include/linux/sunrpc/gss_krb5.h | 25 | ||||
| -rw-r--r-- | net/sunrpc/auth_gss/auth_gss.c | 2 | ||||
| -rw-r--r-- | net/sunrpc/auth_gss/gss_krb5_crypto.c | 38 | ||||
| -rw-r--r-- | net/sunrpc/auth_gss/gss_krb5_wrap.c | 6 |
4 files changed, 66 insertions, 5 deletions
diff --git a/include/linux/sunrpc/gss_krb5.h b/include/linux/sunrpc/gss_krb5.h index e7bbdba474d5..31bb8a538bf1 100644 --- a/include/linux/sunrpc/gss_krb5.h +++ b/include/linux/sunrpc/gss_krb5.h @@ -40,6 +40,12 @@ #include <linux/sunrpc/gss_err.h> #include <linux/sunrpc/gss_asn1.h> +/* Maximum checksum function output for the supported crypto algorithms */ +#define GSS_KRB5_MAX_CKSUM_LEN (20) + +/* Maximum blocksize for the supported crypto algorithms */ +#define GSS_KRB5_MAX_BLOCKSIZE (16) + struct krb5_ctx { int initiate; /* 1 = initiating, 0 = accepting */ struct crypto_blkcipher *enc; @@ -113,6 +119,22 @@ enum seal_alg { #define ENCTYPE_DES3_CBC_SHA1 0x0010 #define ENCTYPE_UNKNOWN 0x01ff +/* + * This compile-time check verifies that we will not exceed the + * slack space allotted by the client and server auth_gss code + * before they call gss_wrap(). + */ +#define GSS_KRB5_MAX_SLACK_NEEDED \ + (GSS_KRB5_TOK_HDR_LEN /* gss token header */ \ + + GSS_KRB5_MAX_CKSUM_LEN /* gss token checksum */ \ + + GSS_KRB5_MAX_BLOCKSIZE /* confounder */ \ + + GSS_KRB5_MAX_BLOCKSIZE /* possible padding */ \ + + GSS_KRB5_TOK_HDR_LEN /* encrypted hdr in v2 token */\ + + GSS_KRB5_MAX_CKSUM_LEN /* encryption hmac */ \ + + 4 + 4 /* RPC verifier */ \ + + GSS_KRB5_TOK_HDR_LEN \ + + GSS_KRB5_MAX_CKSUM_LEN) + s32 make_checksum(char *, char *header, int hdrlen, struct xdr_buf *body, int body_offset, struct xdr_netobj *cksum); @@ -157,3 +179,6 @@ s32 krb5_get_seq_num(struct crypto_blkcipher *key, unsigned char *cksum, unsigned char *buf, int *direction, u32 *seqnum); + +int +xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen); diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c index c389ccf6437d..75602ece58eb 100644 --- a/net/sunrpc/auth_gss/auth_gss.c +++ b/net/sunrpc/auth_gss/auth_gss.c @@ -61,7 +61,7 @@ static const struct rpc_credops gss_nullops; # define RPCDBG_FACILITY RPCDBG_AUTH #endif -#define GSS_CRED_SLACK 1024 +#define GSS_CRED_SLACK (RPC_MAX_AUTH_SIZE * 2) /* length of a krb5 verifier (48), plus data added before arguments when * using integrity (two 4-byte integers): */ #define GSS_VERF_SLACK 100 diff --git a/net/sunrpc/auth_gss/gss_krb5_crypto.c b/net/sunrpc/auth_gss/gss_krb5_crypto.c index e9b636176687..746b3e139aed 100644 --- a/net/sunrpc/auth_gss/gss_krb5_crypto.c +++ b/net/sunrpc/auth_gss/gss_krb5_crypto.c @@ -325,3 +325,41 @@ gss_decrypt_xdr_buf(struct crypto_blkcipher *tfm, struct xdr_buf *buf, return xdr_process_buf(buf, offset, buf->len - offset, decryptor, &desc); } + +/* + * This function makes the assumption that it was ultimately called + * from gss_wrap(). + * + * The client auth_gss code moves any existing tail data into a + * separate page before calling gss_wrap. + * The server svcauth_gss code ensures that both the head and the + * tail have slack space of RPC_MAX_AUTH_SIZE before calling gss_wrap. + * + * Even with that guarantee, this function may be called more than + * once in the processing of gss_wrap(). The best we can do is + * verify at compile-time (see GSS_KRB5_SLACK_CHECK) that the + * largest expected shift will fit within RPC_MAX_AUTH_SIZE. + * At run-time we can verify that a single invocation of this + * function doesn't attempt to use more the RPC_MAX_AUTH_SIZE. + */ + +int +xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen) +{ + u8 *p; + + if (shiftlen == 0) + return 0; + + BUILD_BUG_ON(GSS_KRB5_MAX_SLACK_NEEDED > RPC_MAX_AUTH_SIZE); + BUG_ON(shiftlen > RPC_MAX_AUTH_SIZE); + + p = buf->head[0].iov_base + base; + + memmove(p + shiftlen, p, buf->head[0].iov_len - base); + + buf->head[0].iov_len += shiftlen; + buf->len += shiftlen; + + return 0; +} diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c index a6e905637e03..496281fabb91 100644 --- a/net/sunrpc/auth_gss/gss_krb5_wrap.c +++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c @@ -155,11 +155,9 @@ gss_wrap_kerberos(struct gss_ctx *ctx, int offset, ptr = buf->head[0].iov_base + offset; /* shift data to make room for header. */ + xdr_extend_head(buf, offset, headlen); + /* XXX Would be cleverer to encrypt while copying. */ - /* XXX bounds checking, slack, etc. */ - memmove(ptr + headlen, ptr, buf->head[0].iov_len - offset); - buf->head[0].iov_len += headlen; - buf->len += headlen; BUG_ON((buf->len - offset - headlen) % blocksize); g_make_token_header(&kctx->mech_used, |