diff options
Diffstat (limited to 'net/sunrpc/auth_gss/gss_krb5_wrap.c')
-rw-r--r-- | net/sunrpc/auth_gss/gss_krb5_wrap.c | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c new file mode 100644 index 0000000000..b3e1738ff6 --- /dev/null +++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c @@ -0,0 +1,237 @@ +/* + * COPYRIGHT (c) 2008 + * The Regents of the University of Michigan + * ALL RIGHTS RESERVED + * + * Permission is granted to use, copy, create derivative works + * and redistribute this software and such derivative works + * for any purpose, so long as the name of The University of + * Michigan is not used in any advertising or publicity + * pertaining to the use of distribution of this software + * without specific, written prior authorization. If the + * above copyright notice or any other identification of the + * University of Michigan is included in any copy of any + * portion of this software, then the disclaimer below must + * also be included. + * + * THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION + * FROM THE UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY + * PURPOSE, AND WITHOUT WARRANTY BY THE UNIVERSITY OF + * MICHIGAN OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING + * WITHOUT LIMITATION THE IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE + * REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE LIABLE + * FOR ANY DAMAGES, INCLUDING SPECIAL, INDIRECT, INCIDENTAL, OR + * CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM ARISING + * OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN + * IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGES. + */ + +#include <crypto/skcipher.h> +#include <linux/types.h> +#include <linux/jiffies.h> +#include <linux/sunrpc/gss_krb5.h> +#include <linux/pagemap.h> + +#include "gss_krb5_internal.h" + +#if IS_ENABLED(CONFIG_SUNRPC_DEBUG) +# define RPCDBG_FACILITY RPCDBG_AUTH +#endif + +/* + * We can shift data by up to LOCAL_BUF_LEN bytes in a pass. If we need + * to do more than that, we shift repeatedly. Kevin Coffman reports + * seeing 28 bytes as the value used by Microsoft clients and servers + * with AES, so this constant is chosen to allow handling 28 in one pass + * without using too much stack space. + * + * If that proves to a problem perhaps we could use a more clever + * algorithm. + */ +#define LOCAL_BUF_LEN 32u + +static void rotate_buf_a_little(struct xdr_buf *buf, unsigned int shift) +{ + char head[LOCAL_BUF_LEN]; + char tmp[LOCAL_BUF_LEN]; + unsigned int this_len, i; + + BUG_ON(shift > LOCAL_BUF_LEN); + + read_bytes_from_xdr_buf(buf, 0, head, shift); + for (i = 0; i + shift < buf->len; i += LOCAL_BUF_LEN) { + this_len = min(LOCAL_BUF_LEN, buf->len - (i + shift)); + read_bytes_from_xdr_buf(buf, i+shift, tmp, this_len); + write_bytes_to_xdr_buf(buf, i, tmp, this_len); + } + write_bytes_to_xdr_buf(buf, buf->len - shift, head, shift); +} + +static void _rotate_left(struct xdr_buf *buf, unsigned int shift) +{ + int shifted = 0; + int this_shift; + + shift %= buf->len; + while (shifted < shift) { + this_shift = min(shift - shifted, LOCAL_BUF_LEN); + rotate_buf_a_little(buf, this_shift); + shifted += this_shift; + } +} + +static void rotate_left(u32 base, struct xdr_buf *buf, unsigned int shift) +{ + struct xdr_buf subbuf; + + xdr_buf_subsegment(buf, &subbuf, base, buf->len - base); + _rotate_left(&subbuf, shift); +} + +u32 +gss_krb5_wrap_v2(struct krb5_ctx *kctx, int offset, + struct xdr_buf *buf, struct page **pages) +{ + u8 *ptr; + time64_t now; + u8 flags = 0x00; + __be16 *be16ptr; + __be64 *be64ptr; + u32 err; + + dprintk("RPC: %s\n", __func__); + + /* make room for gss token header */ + if (xdr_extend_head(buf, offset, GSS_KRB5_TOK_HDR_LEN)) + return GSS_S_FAILURE; + + /* construct gss token header */ + ptr = buf->head[0].iov_base + offset; + *ptr++ = (unsigned char) ((KG2_TOK_WRAP>>8) & 0xff); + *ptr++ = (unsigned char) (KG2_TOK_WRAP & 0xff); + + if ((kctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0) + flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR; + if ((kctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY) != 0) + flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY; + /* We always do confidentiality in wrap tokens */ + flags |= KG2_TOKEN_FLAG_SEALED; + + *ptr++ = flags; + *ptr++ = 0xff; + be16ptr = (__be16 *)ptr; + + *be16ptr++ = 0; + /* "inner" token header always uses 0 for RRC */ + *be16ptr++ = 0; + + be64ptr = (__be64 *)be16ptr; + *be64ptr = cpu_to_be64(atomic64_fetch_inc(&kctx->seq_send64)); + + err = (*kctx->gk5e->encrypt)(kctx, offset, buf, pages); + if (err) + return err; + + now = ktime_get_real_seconds(); + return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; +} + +u32 +gss_krb5_unwrap_v2(struct krb5_ctx *kctx, int offset, int len, + struct xdr_buf *buf, unsigned int *slack, + unsigned int *align) +{ + time64_t now; + u8 *ptr; + u8 flags = 0x00; + u16 ec, rrc; + int err; + u32 headskip, tailskip; + u8 decrypted_hdr[GSS_KRB5_TOK_HDR_LEN]; + unsigned int movelen; + + + dprintk("RPC: %s\n", __func__); + + ptr = buf->head[0].iov_base + offset; + + if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_WRAP) + return GSS_S_DEFECTIVE_TOKEN; + + flags = ptr[2]; + if ((!kctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) || + (kctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR))) + return GSS_S_BAD_SIG; + + if ((flags & KG2_TOKEN_FLAG_SEALED) == 0) { + dprintk("%s: token missing expected sealed flag\n", __func__); + return GSS_S_DEFECTIVE_TOKEN; + } + + if (ptr[3] != 0xff) + return GSS_S_DEFECTIVE_TOKEN; + + ec = be16_to_cpup((__be16 *)(ptr + 4)); + rrc = be16_to_cpup((__be16 *)(ptr + 6)); + + /* + * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss + * doesn't want it checked; see page 6 of rfc 2203. + */ + + if (rrc != 0) + rotate_left(offset + 16, buf, rrc); + + err = (*kctx->gk5e->decrypt)(kctx, offset, len, buf, + &headskip, &tailskip); + if (err) + return GSS_S_FAILURE; + + /* + * Retrieve the decrypted gss token header and verify + * it against the original + */ + err = read_bytes_from_xdr_buf(buf, + len - GSS_KRB5_TOK_HDR_LEN - tailskip, + decrypted_hdr, GSS_KRB5_TOK_HDR_LEN); + if (err) { + dprintk("%s: error %u getting decrypted_hdr\n", __func__, err); + return GSS_S_FAILURE; + } + if (memcmp(ptr, decrypted_hdr, 6) + || memcmp(ptr + 8, decrypted_hdr + 8, 8)) { + dprintk("%s: token hdr, plaintext hdr mismatch!\n", __func__); + return GSS_S_FAILURE; + } + + /* do sequencing checks */ + + /* it got through unscathed. Make sure the context is unexpired */ + now = ktime_get_real_seconds(); + if (now > kctx->endtime) + return GSS_S_CONTEXT_EXPIRED; + + /* + * Move the head data back to the right position in xdr_buf. + * We ignore any "ec" data since it might be in the head or + * the tail, and we really don't need to deal with it. + * Note that buf->head[0].iov_len may indicate the available + * head buffer space rather than that actually occupied. + */ + movelen = min_t(unsigned int, buf->head[0].iov_len, len); + movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip; + BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen > + buf->head[0].iov_len); + memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen); + buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip; + buf->len = len - (GSS_KRB5_TOK_HDR_LEN + headskip); + + /* Trim off the trailing "extra count" and checksum blob */ + xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip); + + *align = XDR_QUADLEN(GSS_KRB5_TOK_HDR_LEN + headskip); + *slack = *align + XDR_QUADLEN(ec + GSS_KRB5_TOK_HDR_LEN + tailskip); + return GSS_S_COMPLETE; +} |