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author | J. Bruce Fields <bfields@fieldses.org> | 2005-10-13 20:55:13 (GMT) |
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committer | Trond Myklebust <Trond.Myklebust@netapp.com> | 2005-10-19 06:19:46 (GMT) |
commit | 14ae162c24d985593d5b19437d7f3d8fd0062b59 (patch) | |
tree | 750fbc08e6a6e0cb00bfad7c871144a757ac43de /net/sunrpc/auth_gss/gss_krb5_wrap.c | |
parent | bfa91516b57483fc9c81d8d90325fd2c3c16ac48 (diff) | |
download | linux-fsl-qoriq-14ae162c24d985593d5b19437d7f3d8fd0062b59.tar.xz |
RPCSEC_GSS: Add support for privacy to krb5 rpcsec_gss mechanism.
Add support for privacy to the krb5 rpcsec_gss mechanism.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'net/sunrpc/auth_gss/gss_krb5_wrap.c')
-rw-r--r-- | net/sunrpc/auth_gss/gss_krb5_wrap.c | 370 |
1 files changed, 370 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 0000000..ddcde6e --- /dev/null +++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c @@ -0,0 +1,370 @@ +#include <linux/types.h> +#include <linux/slab.h> +#include <linux/jiffies.h> +#include <linux/sunrpc/gss_krb5.h> +#include <linux/random.h> +#include <linux/pagemap.h> +#include <asm/scatterlist.h> +#include <linux/crypto.h> + +#ifdef RPC_DEBUG +# define RPCDBG_FACILITY RPCDBG_AUTH +#endif + +static inline int +gss_krb5_padding(int blocksize, int length) +{ + /* Most of the code is block-size independent but currently we + * use only 8: */ + BUG_ON(blocksize != 8); + return 8 - (length & 7); +} + +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; + int 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) { + int last = (buf->page_base + len - 1) + >>PAGE_CACHE_SHIFT; + int offset = (buf->page_base + len - 1) + & (PAGE_CACHE_SIZE - 1); + ptr = kmap_atomic(buf->pages[last], KM_SKB_SUNRPC_DATA); + pad = *(ptr + offset); + kunmap_atomic(ptr, KM_SKB_SUNRPC_DATA); + 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; +} + +static inline void +make_confounder(char *p, int blocksize) +{ + 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. */ + + BUG_ON(blocksize != 8); + *q = i++; +} + +/* 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. */ + +u32 +gss_wrap_kerberos(struct gss_ctx *ctx, u32 qop, int offset, + struct xdr_buf *buf, struct page **pages) +{ + struct krb5_ctx *kctx = ctx->internal_ctx_id; + s32 checksum_type; + struct xdr_netobj md5cksum = {.len = 0, .data = NULL}; + int blocksize = 0, plainlen; + unsigned char *ptr, *krb5_hdr, *msg_start; + s32 now; + int headlen; + struct page **tmp_pages; + + dprintk("RPC: gss_wrap_kerberos\n"); + + now = get_seconds(); + + if (qop != 0) + goto out_err; + + switch (kctx->signalg) { + case SGN_ALG_DES_MAC_MD5: + checksum_type = CKSUMTYPE_RSA_MD5; + break; + default: + dprintk("RPC: gss_krb5_seal: kctx->signalg %d not" + " supported\n", kctx->signalg); + goto out_err; + } + if (kctx->sealalg != SEAL_ALG_NONE && kctx->sealalg != SEAL_ALG_DES) { + dprintk("RPC: gss_krb5_seal: kctx->sealalg %d not supported\n", + kctx->sealalg); + goto out_err; + } + + blocksize = crypto_tfm_alg_blocksize(kctx->enc); + gss_krb5_add_padding(buf, offset, blocksize); + BUG_ON((buf->len - offset) % blocksize); + plainlen = blocksize + buf->len - offset; + + headlen = g_token_size(&kctx->mech_used, 22 + plainlen) - + (buf->len - offset); + + ptr = buf->head[0].iov_base + offset; + /* shift data to make room for header. */ + /* 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, 22 + plainlen, &ptr); + + + *ptr++ = (unsigned char) ((KG_TOK_WRAP_MSG>>8)&0xff); + *ptr++ = (unsigned char) (KG_TOK_WRAP_MSG&0xff); + + /* ptr now at byte 2 of header described in rfc 1964, section 1.2.1: */ + krb5_hdr = ptr - 2; + msg_start = krb5_hdr + 24; + /* XXXJBF: */ BUG_ON(buf->head[0].iov_base + offset + headlen != msg_start + blocksize); + + *(u16 *)(krb5_hdr + 2) = htons(kctx->signalg); + memset(krb5_hdr + 4, 0xff, 4); + *(u16 *)(krb5_hdr + 4) = htons(kctx->sealalg); + + make_confounder(msg_start, blocksize); + + /* XXXJBF: UGH!: */ + tmp_pages = buf->pages; + buf->pages = pages; + if (make_checksum(checksum_type, krb5_hdr, 8, buf, + offset + headlen - blocksize, &md5cksum)) + goto out_err; + buf->pages = tmp_pages; + + switch (kctx->signalg) { + case SGN_ALG_DES_MAC_MD5: + if (krb5_encrypt(kctx->seq, NULL, md5cksum.data, + md5cksum.data, md5cksum.len)) + goto out_err; + memcpy(krb5_hdr + 16, + md5cksum.data + md5cksum.len - KRB5_CKSUM_LENGTH, + KRB5_CKSUM_LENGTH); + + dprintk("RPC: make_seal_token: cksum data: \n"); + print_hexl((u32 *) (krb5_hdr + 16), KRB5_CKSUM_LENGTH, 0); + break; + default: + BUG(); + } + + kfree(md5cksum.data); + + /* XXX would probably be more efficient to compute checksum + * and encrypt at the same time: */ + if ((krb5_make_seq_num(kctx->seq, kctx->initiate ? 0 : 0xff, + kctx->seq_send, krb5_hdr + 16, krb5_hdr + 8))) + goto out_err; + + if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize, + pages)) + goto out_err; + + kctx->seq_send++; + + return ((kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE); +out_err: + if (md5cksum.data) kfree(md5cksum.data); + return GSS_S_FAILURE; +} + +u32 +gss_unwrap_kerberos(struct gss_ctx *ctx, u32 *qop, int offset, + struct xdr_buf *buf) +{ + struct krb5_ctx *kctx = ctx->internal_ctx_id; + int signalg; + int sealalg; + s32 checksum_type; + struct xdr_netobj md5cksum = {.len = 0, .data = NULL}; + s32 now; + int direction; + s32 seqnum; + unsigned char *ptr; + int bodysize; + u32 ret = GSS_S_DEFECTIVE_TOKEN; + void *data_start, *orig_start; + int data_len; + int blocksize; + + 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)) + goto out; + + if ((*ptr++ != ((KG_TOK_WRAP_MSG>>8)&0xff)) || + (*ptr++ != (KG_TOK_WRAP_MSG &0xff)) ) + goto out; + + /* XXX sanity-check bodysize?? */ + + /* get the sign and seal algorithms */ + + signalg = ptr[0] + (ptr[1] << 8); + sealalg = ptr[2] + (ptr[3] << 8); + + /* Sanity checks */ + + if ((ptr[4] != 0xff) || (ptr[5] != 0xff)) + goto out; + + if (sealalg == 0xffff) + goto out; + + /* in the current spec, there is only one valid seal algorithm per + key type, so a simple comparison is ok */ + + if (sealalg != kctx->sealalg) + goto out; + + /* there are several mappings of seal algorithms to sign algorithms, + but few enough that we can try them all. */ + + if ((kctx->sealalg == SEAL_ALG_NONE && signalg > 1) || + (kctx->sealalg == SEAL_ALG_1 && signalg != SGN_ALG_3) || + (kctx->sealalg == SEAL_ALG_DES3KD && + signalg != SGN_ALG_HMAC_SHA1_DES3_KD)) + goto out; + + if (gss_decrypt_xdr_buf(kctx->enc, buf, + ptr + 22 - (unsigned char *)buf->head[0].iov_base)) + goto out; + + /* compute the checksum of the message */ + + /* initialize the the cksum */ + switch (signalg) { + case SGN_ALG_DES_MAC_MD5: + checksum_type = CKSUMTYPE_RSA_MD5; + break; + default: + ret = GSS_S_DEFECTIVE_TOKEN; + goto out; + } + + switch (signalg) { + case SGN_ALG_DES_MAC_MD5: + ret = make_checksum(checksum_type, ptr - 2, 8, buf, + ptr + 22 - (unsigned char *)buf->head[0].iov_base, &md5cksum); + if (ret) + goto out; + + ret = krb5_encrypt(kctx->seq, NULL, md5cksum.data, + md5cksum.data, md5cksum.len); + if (ret) + goto out; + + if (memcmp(md5cksum.data + 8, ptr + 14, 8)) { + ret = GSS_S_BAD_SIG; + goto out; + } + break; + default: + ret = GSS_S_DEFECTIVE_TOKEN; + goto out; + } + + /* it got through unscathed. Make sure the context is unexpired */ + + if (qop) + *qop = GSS_C_QOP_DEFAULT; + + now = get_seconds(); + + ret = GSS_S_CONTEXT_EXPIRED; + if (now > kctx->endtime) + goto out; + + /* do sequencing checks */ + + ret = GSS_S_BAD_SIG; + if ((ret = krb5_get_seq_num(kctx->seq, ptr + 14, ptr + 6, &direction, + &seqnum))) + goto out; + + if ((kctx->initiate && direction != 0xff) || + (!kctx->initiate && direction != 0)) + goto out; + + /* Copy the data back to the right position. XXX: Would probably be + * better to copy and encrypt at the same time. */ + + blocksize = crypto_tfm_alg_blocksize(kctx->enc); + data_start = ptr + 22 + blocksize; + 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); + + ret = GSS_S_DEFECTIVE_TOKEN; + if (gss_krb5_remove_padding(buf, blocksize)) + goto out; + + ret = GSS_S_COMPLETE; +out: + if (md5cksum.data) kfree(md5cksum.data); + return ret; +} |