lib/mpi: Add mpi sgl helpers (2d4d1eea) · Commits · EulixOS / Software / Kernel

include/linux/mpi.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -31,6 +31,7 @@
		#define G10_MPI_H

		#include <linux/types.h>
		#include <linux/scatterlist.h>

		/* DSI defines */

		@@ -78,6 +79,7 @@ void mpi_swap(MPI a, MPI b);
		MPI do_encode_md(const void *sha_buffer, unsigned nbits);
		MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes);
		MPI mpi_read_from_buffer(const void buffer, unsigned ret_nread);
		MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int len);
		int mpi_fromstr(MPI val, const char *str);
		u32 mpi_get_keyid(MPI a, u32 *keyid);
		void mpi_get_buffer(MPI a, unsigned nbytes, int *sign);
		@@ -85,6 +87,8 @@ int mpi_read_buffer(MPI a, uint8_t buf, unsigned buf_len, unsigned nbytes,
		int *sign);
		void mpi_get_secure_buffer(MPI a, unsigned nbytes, int *sign);
		int mpi_set_buffer(MPI a, const void *buffer, unsigned nbytes, int sign);
		int mpi_write_to_sgl(MPI a, struct scatterlist sg, unsigned nbytes,
		int *sign);

		#define log_mpidump g10_log_mpidump

lib/mpi/mpicoder.c

+196 −0

Original line number	Diff line number	Diff line
		@@ -319,3 +319,199 @@ int mpi_set_buffer(MPI a, const void *xbuffer, unsigned nbytes, int sign)
		return 0;
		}
		EXPORT_SYMBOL_GPL(mpi_set_buffer);

		/**
		* mpi_write_to_sgl() - Funnction exports MPI to an sgl (msb first)
		*
		* This function works in the same way as the mpi_read_buffer, but it
		* takes an sgl instead of u8 * buf.
		*
		* @a: a multi precision integer
		* @sgl: scatterlist to write to. Needs to be at least
		* mpi_get_size(a) long.
		* @nbytes: in/out param - it has the be set to the maximum number of
		* bytes that can be written to sgl. This has to be at least
		* the size of the integer a. On return it receives the actual
		* length of the data written.
		* @sign: if not NULL, it will be set to the sign of a.
		*
		* Return: 0 on success or error code in case of error
		*/
		int mpi_write_to_sgl(MPI a, struct scatterlist sgl, unsigned nbytes,
		int *sign)
		{
		u8 p, p2;
		mpi_limb_t alimb, alimb2;
		unsigned int n = mpi_get_size(a);
		int i, x, y = 0, lzeros = 0, buf_len;

		if (!nbytes \|\| *nbytes < n)
		return -EINVAL;

		if (sign)
		*sign = a->sign;

		p = (void *)&a->d[a->nlimbs] - 1;

		for (i = a->nlimbs * sizeof(alimb) - 1; i >= 0; i--, p--) {
		if (!*p)
		lzeros++;
		else
		break;
		}

		*nbytes = n - lzeros;
		buf_len = sgl->length;
		p2 = sg_virt(sgl);

		for (i = a->nlimbs - 1; i >= 0; i--) {
		alimb = a->d[i];
		p = (u8 *)&alimb2;
		#if BYTES_PER_MPI_LIMB == 4
		*p++ = alimb >> 24;
		*p++ = alimb >> 16;
		*p++ = alimb >> 8;
		*p++ = alimb;
		#elif BYTES_PER_MPI_LIMB == 8
		*p++ = alimb >> 56;
		*p++ = alimb >> 48;
		*p++ = alimb >> 40;
		*p++ = alimb >> 32;
		*p++ = alimb >> 24;
		*p++ = alimb >> 16;
		*p++ = alimb >> 8;
		*p++ = alimb;
		#else
		#error please implement for this limb size.
		#endif
		if (lzeros > 0) {
		if (lzeros >= sizeof(alimb)) {
		p -= sizeof(alimb);
		continue;
		} else {
		mpi_limb_t limb1 = (void )p - sizeof(alimb);
		mpi_limb_t limb2 = (void )p - sizeof(alimb)
		+ lzeros;
		limb1 = limb2;
		p -= lzeros;
		y = lzeros;
		}
		lzeros -= sizeof(alimb);
		}

		p = p - (sizeof(alimb) - y);

		for (x = 0; x < sizeof(alimb) - y; x++) {
		if (!buf_len) {
		sgl = sg_next(sgl);
		if (!sgl)
		return -EINVAL;
		buf_len = sgl->length;
		p2 = sg_virt(sgl);
		}
		p2++ = p++;
		buf_len--;
		}
		y = 0;
		}
		return 0;
		}
		EXPORT_SYMBOL_GPL(mpi_write_to_sgl);

		/*
		* mpi_read_raw_from_sgl() - Function allocates an MPI and populates it with
		* data from the sgl
		*
		* This function works in the same way as the mpi_read_raw_data, but it
		* takes an sgl instead of void * buffer. i.e. it allocates
		* a new MPI and reads the content of the sgl to the MPI.
		*
		* @sgl: scatterlist to read from
		* @len: number of bytes to read
		*
		* Return: Pointer to a new MPI or NULL on error
		*/
		MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int len)
		{
		struct scatterlist *sg;
		int x, i, j, z, lzeros, ents;
		unsigned int nbits, nlimbs, nbytes;
		mpi_limb_t a;
		MPI val = NULL;

		lzeros = 0;
		ents = sg_nents(sgl);

		for_each_sg(sgl, sg, ents, i) {
		const u8 *buff = sg_virt(sg);
		int len = sg->length;

		while (len-- && !*buff++)
		lzeros++;

		if (len && *buff)
		break;

		ents--;
		lzeros = 0;
		}

		sgl = sg;

		if (!ents)
		nbytes = 0;
		else
		nbytes = len - lzeros;

		nbits = nbytes * 8;
		if (nbits > MAX_EXTERN_MPI_BITS) {
		pr_info("MPI: mpi too large (%u bits)\n", nbits);
		return NULL;
		}

		if (nbytes > 0)
		nbits -= count_leading_zeros((u8 )(sg_virt(sgl) + lzeros));
		else
		nbits = 0;

		nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
		val = mpi_alloc(nlimbs);
		if (!val)
		return NULL;

		val->nbits = nbits;
		val->sign = 0;
		val->nlimbs = nlimbs;

		if (nbytes == 0)
		return val;

		j = nlimbs - 1;
		a = 0;
		z = 0;
		x = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
		x %= BYTES_PER_MPI_LIMB;

		for_each_sg(sgl, sg, ents, i) {
		const u8 *buffer = sg_virt(sg) + lzeros;
		int len = sg->length - lzeros;
		int buf_shift = x;

		if (sg_is_last(sg) && (len % BYTES_PER_MPI_LIMB))
		len += BYTES_PER_MPI_LIMB - (len % BYTES_PER_MPI_LIMB);

		for (; x < len + buf_shift; x++) {
		a <<= 8;
		a \|= *buffer++;
		if (((z + x + 1) % BYTES_PER_MPI_LIMB) == 0) {
		val->d[j--] = a;
		a = 0;
		}
		}
		z += x;
		x = 0;
		lzeros = 0;
		}
		return val;
		}
		EXPORT_SYMBOL_GPL(mpi_read_raw_from_sgl);