lib/mpi: Add mpi sgl helpers
Add mpi_read_raw_from_sgl and mpi_write_to_sgl helpers. Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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@ -31,6 +31,7 @@
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#define G10_MPI_H
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#include <linux/types.h>
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#include <linux/scatterlist.h>
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/* DSI defines */
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@ -78,6 +79,7 @@ void mpi_swap(MPI a, MPI b);
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MPI do_encode_md(const void *sha_buffer, unsigned nbits);
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MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes);
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MPI mpi_read_from_buffer(const void *buffer, unsigned *ret_nread);
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MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int len);
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int mpi_fromstr(MPI val, const char *str);
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u32 mpi_get_keyid(MPI a, u32 *keyid);
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void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign);
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@ -85,6 +87,8 @@ int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
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int *sign);
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void *mpi_get_secure_buffer(MPI a, unsigned *nbytes, int *sign);
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int mpi_set_buffer(MPI a, const void *buffer, unsigned nbytes, int sign);
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int mpi_write_to_sgl(MPI a, struct scatterlist *sg, unsigned *nbytes,
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int *sign);
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#define log_mpidump g10_log_mpidump
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@ -319,3 +319,199 @@ int mpi_set_buffer(MPI a, const void *xbuffer, unsigned nbytes, int sign)
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return 0;
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}
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EXPORT_SYMBOL_GPL(mpi_set_buffer);
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/**
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* mpi_write_to_sgl() - Funnction exports MPI to an sgl (msb first)
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*
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* This function works in the same way as the mpi_read_buffer, but it
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* takes an sgl instead of u8 * buf.
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*
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* @a: a multi precision integer
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* @sgl: scatterlist to write to. Needs to be at least
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* mpi_get_size(a) long.
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* @nbytes: in/out param - it has the be set to the maximum number of
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* bytes that can be written to sgl. This has to be at least
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* the size of the integer a. On return it receives the actual
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* length of the data written.
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* @sign: if not NULL, it will be set to the sign of a.
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*
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* Return: 0 on success or error code in case of error
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*/
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int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes,
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int *sign)
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{
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u8 *p, *p2;
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mpi_limb_t alimb, alimb2;
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unsigned int n = mpi_get_size(a);
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int i, x, y = 0, lzeros = 0, buf_len;
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if (!nbytes || *nbytes < n)
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return -EINVAL;
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if (sign)
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*sign = a->sign;
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p = (void *)&a->d[a->nlimbs] - 1;
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for (i = a->nlimbs * sizeof(alimb) - 1; i >= 0; i--, p--) {
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if (!*p)
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lzeros++;
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else
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break;
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}
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*nbytes = n - lzeros;
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buf_len = sgl->length;
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p2 = sg_virt(sgl);
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for (i = a->nlimbs - 1; i >= 0; i--) {
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alimb = a->d[i];
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p = (u8 *)&alimb2;
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#if BYTES_PER_MPI_LIMB == 4
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*p++ = alimb >> 24;
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*p++ = alimb >> 16;
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*p++ = alimb >> 8;
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*p++ = alimb;
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#elif BYTES_PER_MPI_LIMB == 8
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*p++ = alimb >> 56;
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*p++ = alimb >> 48;
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*p++ = alimb >> 40;
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*p++ = alimb >> 32;
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*p++ = alimb >> 24;
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*p++ = alimb >> 16;
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*p++ = alimb >> 8;
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*p++ = alimb;
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#else
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#error please implement for this limb size.
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#endif
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if (lzeros > 0) {
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if (lzeros >= sizeof(alimb)) {
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p -= sizeof(alimb);
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continue;
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} else {
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mpi_limb_t *limb1 = (void *)p - sizeof(alimb);
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mpi_limb_t *limb2 = (void *)p - sizeof(alimb)
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+ lzeros;
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*limb1 = *limb2;
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p -= lzeros;
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y = lzeros;
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}
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lzeros -= sizeof(alimb);
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}
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p = p - (sizeof(alimb) - y);
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for (x = 0; x < sizeof(alimb) - y; x++) {
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if (!buf_len) {
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sgl = sg_next(sgl);
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if (!sgl)
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return -EINVAL;
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buf_len = sgl->length;
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p2 = sg_virt(sgl);
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}
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*p2++ = *p++;
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buf_len--;
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}
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y = 0;
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(mpi_write_to_sgl);
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/*
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* mpi_read_raw_from_sgl() - Function allocates an MPI and populates it with
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* data from the sgl
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*
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* This function works in the same way as the mpi_read_raw_data, but it
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* takes an sgl instead of void * buffer. i.e. it allocates
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* a new MPI and reads the content of the sgl to the MPI.
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*
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* @sgl: scatterlist to read from
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* @len: number of bytes to read
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*
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* Return: Pointer to a new MPI or NULL on error
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*/
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MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int len)
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{
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struct scatterlist *sg;
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int x, i, j, z, lzeros, ents;
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unsigned int nbits, nlimbs, nbytes;
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mpi_limb_t a;
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MPI val = NULL;
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lzeros = 0;
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ents = sg_nents(sgl);
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for_each_sg(sgl, sg, ents, i) {
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const u8 *buff = sg_virt(sg);
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int len = sg->length;
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while (len-- && !*buff++)
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lzeros++;
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if (len && *buff)
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break;
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ents--;
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lzeros = 0;
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}
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sgl = sg;
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if (!ents)
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nbytes = 0;
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else
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nbytes = len - lzeros;
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nbits = nbytes * 8;
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if (nbits > MAX_EXTERN_MPI_BITS) {
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pr_info("MPI: mpi too large (%u bits)\n", nbits);
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return NULL;
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}
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if (nbytes > 0)
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nbits -= count_leading_zeros(*(u8 *)(sg_virt(sgl) + lzeros));
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else
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nbits = 0;
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nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
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val = mpi_alloc(nlimbs);
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if (!val)
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return NULL;
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val->nbits = nbits;
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val->sign = 0;
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val->nlimbs = nlimbs;
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if (nbytes == 0)
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return val;
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j = nlimbs - 1;
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a = 0;
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z = 0;
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x = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
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x %= BYTES_PER_MPI_LIMB;
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for_each_sg(sgl, sg, ents, i) {
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const u8 *buffer = sg_virt(sg) + lzeros;
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int len = sg->length - lzeros;
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int buf_shift = x;
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if (sg_is_last(sg) && (len % BYTES_PER_MPI_LIMB))
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len += BYTES_PER_MPI_LIMB - (len % BYTES_PER_MPI_LIMB);
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for (; x < len + buf_shift; x++) {
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a <<= 8;
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a |= *buffer++;
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if (((z + x + 1) % BYTES_PER_MPI_LIMB) == 0) {
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val->d[j--] = a;
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a = 0;
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}
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}
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z += x;
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x = 0;
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lzeros = 0;
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}
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return val;
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}
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EXPORT_SYMBOL_GPL(mpi_read_raw_from_sgl);
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