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Subject[PATCH 2/2] fix in-place de/encryption bug with highmem
This patch fixes the bug where in-place encryption was not detected
when the same highmem pages is mapped twice to different virtual
addresses.

This adds a parameter to xxx_process to indicate whether this is an
in-place encryption and moves the responsability to the caller using
a helper function scatterwalk.h.

diff -Nur linux.orig/crypto/cipher.c linux/crypto/cipher.c
--- linux.orig/crypto/cipher.c 2004-02-25 23:43:39.125619688 +0100
+++ linux/crypto/cipher.c 2004-02-25 23:44:51.335642096 +0100
@@ -22,7 +22,7 @@

typedef void (cryptfn_t)(void *, u8 *, const u8 *);
typedef void (procfn_t)(struct crypto_tfm *, u8 *,
- u8*, cryptfn_t, int enc, void *);
+ u8*, cryptfn_t, int enc, void *, int);

static inline void xor_64(u8 *a, const u8 *b)
{
@@ -78,7 +78,9 @@

scatterwalk_copychunks(src_p, &walk_in, bsize, 0);

- prfn(tfm, dst_p, src_p, crfn, enc, info);
+ prfn(tfm, dst_p, src_p, crfn, enc, info,
+ scatterwalk_samebuf(&walk_in, &walk_out,
+ src_p, dst_p));

scatterwalk_done(&walk_in, 0, nbytes);

@@ -92,8 +94,8 @@
}
}

-static void cbc_process(struct crypto_tfm *tfm,
- u8 *dst, u8 *src, cryptfn_t fn, int enc, void *info)
+static void cbc_process(struct crypto_tfm *tfm, u8 *dst, u8 *src,
+ cryptfn_t fn, int enc, void *info, int in_place)
{
u8 *iv = info;

@@ -106,9 +108,8 @@
fn(crypto_tfm_ctx(tfm), dst, iv);
memcpy(iv, dst, crypto_tfm_alg_blocksize(tfm));
} else {
- const int need_stack = (src == dst);
- u8 stack[need_stack ? crypto_tfm_alg_blocksize(tfm) : 0];
- u8 *buf = need_stack ? stack : dst;
+ u8 stack[in_place ? crypto_tfm_alg_blocksize(tfm) : 0];
+ u8 *buf = in_place ? stack : dst;

fn(crypto_tfm_ctx(tfm), buf, src);
tfm->crt_u.cipher.cit_xor_block(buf, iv);
@@ -119,7 +120,7 @@
}

static void ecb_process(struct crypto_tfm *tfm, u8 *dst, u8 *src,
- cryptfn_t fn, int enc, void *info)
+ cryptfn_t fn, int enc, void *info, int in_place)
{
fn(crypto_tfm_ctx(tfm), dst, src);
}
diff -Nur linux.orig/crypto/scatterwalk.h linux/crypto/scatterwalk.h
--- linux.orig/crypto/scatterwalk.h 2004-02-25 23:43:39.133618472 +0100
+++ linux/crypto/scatterwalk.h 2004-02-25 23:44:51.342641032 +0100
@@ -33,6 +33,14 @@
return sg + 1;
}

+static inline int scatterwalk_samebuf(struct scatter_walk *walk_in,
+ struct scatter_walk *walk_out,
+ void *src_p, void *dst_p)
+{
+ return walk_in->page == walk_out->page &&
+ walk_in->data == src_p && walk_out->data == dst_p;
+}
+
void *scatterwalk_whichbuf(struct scatter_walk *walk, unsigned int nbytes, void *scratch);
void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
int scatterwalk_copychunks(void *buf, struct scatter_walk *walk, size_t nbytes, int out);
-
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