diff options
Diffstat (limited to 'net/sunrpc/auth_gss/gss_krb5_wrap.c')
| -rw-r--r-- | net/sunrpc/auth_gss/gss_krb5_wrap.c | 626 |
1 files changed, 626 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 000000000..ca7e92a32 --- /dev/null +++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c @@ -0,0 +1,626 @@ +/* + * 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 <linux/types.h> +#include <linux/jiffies.h> +#include <linux/sunrpc/gss_krb5.h> +#include <linux/random.h> +#include <linux/pagemap.h> +#include <linux/crypto.h> + +#if IS_ENABLED(CONFIG_SUNRPC_DEBUG) +# define RPCDBG_FACILITY RPCDBG_AUTH +#endif + +static inline int +gss_krb5_padding(int blocksize, int length) +{ + return blocksize - (length % blocksize); +} + +static inline void +gss_krb5_add_padding(struct xdr_buf *buf, int offset, int blocksize) +{ + int padding = gss_krb5_padding(blocksize, buf->len - offset); + char *p; + struct kvec *iov; + + if (buf->page_len || buf->tail[0].iov_len) + iov = &buf->tail[0]; + else + iov = &buf->head[0]; + p = iov->iov_base + iov->iov_len; + iov->iov_len += padding; + buf->len += padding; + memset(p, padding, padding); +} + +static inline int +gss_krb5_remove_padding(struct xdr_buf *buf, int blocksize) +{ + u8 *ptr; + u8 pad; + size_t len = buf->len; + + if (len <= buf->head[0].iov_len) { + pad = *(u8 *)(buf->head[0].iov_base + len - 1); + if (pad > buf->head[0].iov_len) + return -EINVAL; + buf->head[0].iov_len -= pad; + goto out; + } else + len -= buf->head[0].iov_len; + if (len <= buf->page_len) { + unsigned int last = (buf->page_base + len - 1) + >>PAGE_CACHE_SHIFT; + unsigned int offset = (buf->page_base + len - 1) + & (PAGE_CACHE_SIZE - 1); + ptr = kmap_atomic(buf->pages[last]); + pad = *(ptr + offset); + kunmap_atomic(ptr); + goto out; + } else + len -= buf->page_len; + BUG_ON(len > buf->tail[0].iov_len); + pad = *(u8 *)(buf->tail[0].iov_base + len - 1); +out: + /* XXX: NOTE: we do not adjust the page lengths--they represent + * a range of data in the real filesystem page cache, and we need + * to know that range so the xdr code can properly place read data. + * However adjusting the head length, as we do above, is harmless. + * In the case of a request that fits into a single page, the server + * also uses length and head length together to determine the original + * start of the request to copy the request for deferal; so it's + * easier on the server if we adjust head and tail length in tandem. + * It's not really a problem that we don't fool with the page and + * tail lengths, though--at worst badly formed xdr might lead the + * server to attempt to parse the padding. + * XXX: Document all these weird requirements for gss mechanism + * wrap/unwrap functions. */ + if (pad > blocksize) + return -EINVAL; + if (buf->len > pad) + buf->len -= pad; + else + return -EINVAL; + return 0; +} + +void +gss_krb5_make_confounder(char *p, u32 conflen) +{ + static u64 i = 0; + u64 *q = (u64 *)p; + + /* rfc1964 claims this should be "random". But all that's really + * necessary is that it be unique. And not even that is necessary in + * our case since our "gssapi" implementation exists only to support + * rpcsec_gss, so we know that the only buffers we will ever encrypt + * already begin with a unique sequence number. Just to hedge my bets + * I'll make a half-hearted attempt at something unique, but ensuring + * uniqueness would mean worrying about atomicity and rollover, and I + * don't care enough. */ + + /* initialize to random value */ + if (i == 0) { + i = prandom_u32(); + i = (i << 32) | prandom_u32(); + } + + switch (conflen) { + case 16: + *q++ = i++; + /* fall through */ + case 8: + *q++ = i++; + break; + default: + BUG(); + } +} + +/* Assumptions: the head and tail of inbuf are ours to play with. + * The pages, however, may be real pages in the page cache and we replace + * them with scratch pages from **pages before writing to them. */ +/* XXX: obviously the above should be documentation of wrap interface, + * and shouldn't be in this kerberos-specific file. */ + +/* XXX factor out common code with seal/unseal. */ + +static u32 +gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset, + struct xdr_buf *buf, struct page **pages) +{ + char cksumdata[GSS_KRB5_MAX_CKSUM_LEN]; + struct xdr_netobj md5cksum = {.len = sizeof(cksumdata), + .data = cksumdata}; + int blocksize = 0, plainlen; + unsigned char *ptr, *msg_start; + s32 now; + int headlen; + struct page **tmp_pages; + u32 seq_send; + u8 *cksumkey; + u32 conflen = kctx->gk5e->conflen; + + dprintk("RPC: %s\n", __func__); + + now = get_seconds(); + + blocksize = crypto_blkcipher_blocksize(kctx->enc); + gss_krb5_add_padding(buf, offset, blocksize); + BUG_ON((buf->len - offset) % blocksize); + plainlen = conflen + buf->len - offset; + + headlen = g_token_size(&kctx->mech_used, + GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength + plainlen) - + (buf->len - 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. */ + BUG_ON((buf->len - offset - headlen) % blocksize); + + g_make_token_header(&kctx->mech_used, + GSS_KRB5_TOK_HDR_LEN + + kctx->gk5e->cksumlength + plainlen, &ptr); + + + /* ptr now at header described in rfc 1964, section 1.2.1: */ + ptr[0] = (unsigned char) ((KG_TOK_WRAP_MSG >> 8) & 0xff); + ptr[1] = (unsigned char) (KG_TOK_WRAP_MSG & 0xff); + + msg_start = ptr + GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength; + + /* + * signalg and sealalg are stored as if they were converted from LE + * to host endian, even though they're opaque pairs of bytes according + * to the RFC. + */ + *(__le16 *)(ptr + 2) = cpu_to_le16(kctx->gk5e->signalg); + *(__le16 *)(ptr + 4) = cpu_to_le16(kctx->gk5e->sealalg); + ptr[6] = 0xff; + ptr[7] = 0xff; + + gss_krb5_make_confounder(msg_start, conflen); + + if (kctx->gk5e->keyed_cksum) + cksumkey = kctx->cksum; + else + cksumkey = NULL; + + /* XXXJBF: UGH!: */ + tmp_pages = buf->pages; + buf->pages = pages; + if (make_checksum(kctx, ptr, 8, buf, offset + headlen - conflen, + cksumkey, KG_USAGE_SEAL, &md5cksum)) + return GSS_S_FAILURE; + buf->pages = tmp_pages; + + memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len); + + spin_lock(&krb5_seq_lock); + seq_send = kctx->seq_send++; + spin_unlock(&krb5_seq_lock); + + /* XXX would probably be more efficient to compute checksum + * and encrypt at the same time: */ + if ((krb5_make_seq_num(kctx, kctx->seq, kctx->initiate ? 0 : 0xff, + seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8))) + return GSS_S_FAILURE; + + if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) { + struct crypto_blkcipher *cipher; + int err; + cipher = crypto_alloc_blkcipher(kctx->gk5e->encrypt_name, 0, + CRYPTO_ALG_ASYNC); + if (IS_ERR(cipher)) + return GSS_S_FAILURE; + + krb5_rc4_setup_enc_key(kctx, cipher, seq_send); + + err = gss_encrypt_xdr_buf(cipher, buf, + offset + headlen - conflen, pages); + crypto_free_blkcipher(cipher); + if (err) + return GSS_S_FAILURE; + } else { + if (gss_encrypt_xdr_buf(kctx->enc, buf, + offset + headlen - conflen, pages)) + return GSS_S_FAILURE; + } + + return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; +} + +static u32 +gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf) +{ + int signalg; + int sealalg; + char cksumdata[GSS_KRB5_MAX_CKSUM_LEN]; + struct xdr_netobj md5cksum = {.len = sizeof(cksumdata), + .data = cksumdata}; + s32 now; + int direction; + s32 seqnum; + unsigned char *ptr; + int bodysize; + void *data_start, *orig_start; + int data_len; + int blocksize; + u32 conflen = kctx->gk5e->conflen; + int crypt_offset; + u8 *cksumkey; + + dprintk("RPC: gss_unwrap_kerberos\n"); + + ptr = (u8 *)buf->head[0].iov_base + offset; + if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr, + buf->len - offset)) + return GSS_S_DEFECTIVE_TOKEN; + + if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) || + (ptr[1] != (KG_TOK_WRAP_MSG & 0xff))) + return GSS_S_DEFECTIVE_TOKEN; + + /* XXX sanity-check bodysize?? */ + + /* get the sign and seal algorithms */ + + signalg = ptr[2] + (ptr[3] << 8); + if (signalg != kctx->gk5e->signalg) + return GSS_S_DEFECTIVE_TOKEN; + + sealalg = ptr[4] + (ptr[5] << 8); + if (sealalg != kctx->gk5e->sealalg) + return GSS_S_DEFECTIVE_TOKEN; + + if ((ptr[6] != 0xff) || (ptr[7] != 0xff)) + return GSS_S_DEFECTIVE_TOKEN; + + /* + * Data starts after token header and checksum. ptr points + * to the beginning of the token header + */ + crypt_offset = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) - + (unsigned char *)buf->head[0].iov_base; + + /* + * Need plaintext seqnum to derive encryption key for arcfour-hmac + */ + if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN, + ptr + 8, &direction, &seqnum)) + return GSS_S_BAD_SIG; + + if ((kctx->initiate && direction != 0xff) || + (!kctx->initiate && direction != 0)) + return GSS_S_BAD_SIG; + + if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) { + struct crypto_blkcipher *cipher; + int err; + + cipher = crypto_alloc_blkcipher(kctx->gk5e->encrypt_name, 0, + CRYPTO_ALG_ASYNC); + if (IS_ERR(cipher)) + return GSS_S_FAILURE; + + krb5_rc4_setup_enc_key(kctx, cipher, seqnum); + + err = gss_decrypt_xdr_buf(cipher, buf, crypt_offset); + crypto_free_blkcipher(cipher); + if (err) + return GSS_S_DEFECTIVE_TOKEN; + } else { + if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset)) + return GSS_S_DEFECTIVE_TOKEN; + } + + if (kctx->gk5e->keyed_cksum) + cksumkey = kctx->cksum; + else + cksumkey = NULL; + + if (make_checksum(kctx, ptr, 8, buf, crypt_offset, + cksumkey, KG_USAGE_SEAL, &md5cksum)) + return GSS_S_FAILURE; + + if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN, + kctx->gk5e->cksumlength)) + return GSS_S_BAD_SIG; + + /* it got through unscathed. Make sure the context is unexpired */ + + now = get_seconds(); + + if (now > kctx->endtime) + return GSS_S_CONTEXT_EXPIRED; + + /* do sequencing checks */ + + /* Copy the data back to the right position. XXX: Would probably be + * better to copy and encrypt at the same time. */ + + blocksize = crypto_blkcipher_blocksize(kctx->enc); + data_start = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) + + conflen; + orig_start = buf->head[0].iov_base + offset; + data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start; + memmove(orig_start, data_start, data_len); + buf->head[0].iov_len -= (data_start - orig_start); + buf->len -= (data_start - orig_start); + + if (gss_krb5_remove_padding(buf, blocksize)) + return GSS_S_DEFECTIVE_TOKEN; + + return GSS_S_COMPLETE; +} + +/* + * 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); +} + +static u32 +gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset, + struct xdr_buf *buf, struct page **pages) +{ + int blocksize; + u8 *ptr, *plainhdr; + s32 now; + u8 flags = 0x00; + __be16 *be16ptr; + __be64 *be64ptr; + u32 err; + + dprintk("RPC: %s\n", __func__); + + if (kctx->gk5e->encrypt_v2 == NULL) + return GSS_S_FAILURE; + + /* 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 = plainhdr = 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; + + blocksize = crypto_blkcipher_blocksize(kctx->acceptor_enc); + *be16ptr++ = 0; + /* "inner" token header always uses 0 for RRC */ + *be16ptr++ = 0; + + be64ptr = (__be64 *)be16ptr; + spin_lock(&krb5_seq_lock); + *be64ptr = cpu_to_be64(kctx->seq_send64++); + spin_unlock(&krb5_seq_lock); + + err = (*kctx->gk5e->encrypt_v2)(kctx, offset, buf, pages); + if (err) + return err; + + now = get_seconds(); + return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; +} + +static u32 +gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf) +{ + s32 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__); + + if (kctx->gk5e->decrypt_v2 == NULL) + return GSS_S_FAILURE; + + 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_v2)(kctx, offset, 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, + 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 = get_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, buf->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 -= 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); + return GSS_S_COMPLETE; +} + +u32 +gss_wrap_kerberos(struct gss_ctx *gctx, int offset, + struct xdr_buf *buf, struct page **pages) +{ + struct krb5_ctx *kctx = gctx->internal_ctx_id; + + switch (kctx->enctype) { + default: + BUG(); + case ENCTYPE_DES_CBC_RAW: + case ENCTYPE_DES3_CBC_RAW: + case ENCTYPE_ARCFOUR_HMAC: + return gss_wrap_kerberos_v1(kctx, offset, buf, pages); + case ENCTYPE_AES128_CTS_HMAC_SHA1_96: + case ENCTYPE_AES256_CTS_HMAC_SHA1_96: + return gss_wrap_kerberos_v2(kctx, offset, buf, pages); + } +} + +u32 +gss_unwrap_kerberos(struct gss_ctx *gctx, int offset, struct xdr_buf *buf) +{ + struct krb5_ctx *kctx = gctx->internal_ctx_id; + + switch (kctx->enctype) { + default: + BUG(); + case ENCTYPE_DES_CBC_RAW: + case ENCTYPE_DES3_CBC_RAW: + case ENCTYPE_ARCFOUR_HMAC: + return gss_unwrap_kerberos_v1(kctx, offset, buf); + case ENCTYPE_AES128_CTS_HMAC_SHA1_96: + case ENCTYPE_AES256_CTS_HMAC_SHA1_96: + return gss_unwrap_kerberos_v2(kctx, offset, buf); + } +} + |