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authorNamjae Jeon <linkinjeon@kernel.org>2026-06-10 18:44:55 +0900
committerSteve French <stfrench@microsoft.com>2026-06-16 18:57:21 -0500
commit0121b154147f5affd1039ca4f8d9a0fc194142f6 (patch)
tree2db7c206cbc729183a4da93bb7a1ff536948c7c1 /fs
parent13f3942f2bf45856bb751faed2f0c4618f41ca20 (diff)
downloadath-0121b154147f5affd1039ca4f8d9a0fc194142f6.tar.gz
smb: move LZ77 compression into common code
Move the LZ77 codec in cifs.ko to smb/common/ so both the SMB client and ksmbd can use it. Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/smb/client/Makefile2
-rw-r--r--fs/smb/client/compress.c12
-rw-r--r--fs/smb/client/compress.h28
-rw-r--r--fs/smb/common/Makefile3
-rw-r--r--fs/smb/common/compress/compress.h22
-rw-r--r--fs/smb/common/compress/lz77.c (renamed from fs/smb/client/compress/lz77.c)136
-rw-r--r--fs/smb/common/compress/lz77.h (renamed from fs/smb/client/compress/lz77.h)17
7 files changed, 176 insertions, 44 deletions
diff --git a/fs/smb/client/Makefile b/fs/smb/client/Makefile
index 6e83b5204699c..fc6b9d35c9624 100644
--- a/fs/smb/client/Makefile
+++ b/fs/smb/client/Makefile
@@ -42,7 +42,7 @@ cifs-$(CONFIG_CIFS_ALLOW_INSECURE_LEGACY) += \
smb1session.o \
smb1transport.o
-cifs-$(CONFIG_CIFS_COMPRESSION) += compress.o compress/lz77.o
+cifs-$(CONFIG_CIFS_COMPRESSION) += compress.o
ifneq ($(CONFIG_CIFS_ALLOW_INSECURE_LEGACY),)
#
diff --git a/fs/smb/client/compress.c b/fs/smb/client/compress.c
index be9023f841e69..8f08609707414 100644
--- a/fs/smb/client/compress.c
+++ b/fs/smb/client/compress.c
@@ -22,7 +22,7 @@
#include "cifsproto.h"
#include "smb2proto.h"
-#include "compress/lz77.h"
+#include "../common/compress/lz77.h"
#include "compress.h"
/*
@@ -44,6 +44,11 @@ struct bucket {
unsigned int count;
};
+static inline size_t pow4(size_t n)
+{
+ return n * n * n * n;
+}
+
/*
* has_low_entropy() - Compute Shannon entropy of the sampled data.
* @bkt: Bytes counts of the sample.
@@ -65,7 +70,6 @@ static bool has_low_entropy(struct bucket *bkt, size_t slen)
const size_t threshold = 65, max_entropy = 8 * ilog2(16);
size_t i, p, p2, len, sum = 0;
-#define pow4(n) (n * n * n * n)
len = ilog2(pow4(slen));
for (i = 0; i < 256 && bkt[i].count > 0; i++) {
@@ -329,14 +333,14 @@ int smb_compress(struct TCP_Server_Info *server, struct smb_rqst *rq, compress_s
goto err_free;
}
- dlen = lz77_compressed_alloc_size(slen);
+ dlen = smb_lz77_compressed_alloc_size(slen);
dst = kvzalloc(dlen, GFP_KERNEL);
if (!dst) {
ret = -ENOMEM;
goto err_free;
}
- ret = lz77_compress(src, slen, dst, &dlen);
+ ret = smb_lz77_compress(src, slen, dst, &dlen);
if (!ret) {
struct smb2_compression_hdr hdr = { 0 };
struct smb_rqst comp_rq = { .rq_nvec = 3, };
diff --git a/fs/smb/client/compress.h b/fs/smb/client/compress.h
index 2679baca129b7..e08e6d339d21e 100644
--- a/fs/smb/client/compress.h
+++ b/fs/smb/client/compress.h
@@ -18,6 +18,7 @@
#include <linux/uio.h>
#include <linux/kernel.h>
#include "../common/smb2pdu.h"
+#include "../common/compress/compress.h"
#include "cifsglob.h"
/* sizeof(smb2_compression_hdr) - sizeof(OriginalPayloadSize) */
@@ -34,29 +35,6 @@ int smb_compress(struct TCP_Server_Info *server, struct smb_rqst *rq,
compress_send_fn send_fn);
bool should_compress(const struct cifs_tcon *tcon, const struct smb_rqst *rq);
-/*
- * smb_compress_alg_valid() - Validate a compression algorithm.
- * @alg: Compression algorithm to check.
- * @valid_none: Conditional check whether NONE algorithm should be
- * considered valid or not.
- *
- * If @alg is SMB3_COMPRESS_NONE, this function returns @valid_none.
- *
- * Note that 'NONE' (0) compressor type is considered invalid in protocol
- * negotiation, as it's never requested to/returned from the server.
- *
- * Return: true if @alg is valid/supported, false otherwise.
- */
-static __always_inline int smb_compress_alg_valid(__le16 alg, bool valid_none)
-{
- if (alg == SMB3_COMPRESS_NONE)
- return valid_none;
-
- if (alg == SMB3_COMPRESS_LZ77 || alg == SMB3_COMPRESS_PATTERN)
- return true;
-
- return false;
-}
#else /* !CONFIG_CIFS_COMPRESSION */
static inline int smb_compress(void *unused1, void *unused2, void *unused3)
{
@@ -68,9 +46,5 @@ static inline bool should_compress(void *unused1, void *unused2)
return false;
}
-static inline int smb_compress_alg_valid(__le16 unused1, bool unused2)
-{
- return -EOPNOTSUPP;
-}
#endif /* !CONFIG_CIFS_COMPRESSION */
#endif /* _SMB_COMPRESS_H */
diff --git a/fs/smb/common/Makefile b/fs/smb/common/Makefile
index 9e0730a385fb1..bd188d36fb6b5 100644
--- a/fs/smb/common/Makefile
+++ b/fs/smb/common/Makefile
@@ -4,3 +4,6 @@
#
obj-$(CONFIG_SMBFS) += cifs_md4.o
+obj-$(CONFIG_SMBFS) += smb_compress.o
+
+smb_compress-y := compress/lz77.o
diff --git a/fs/smb/common/compress/compress.h b/fs/smb/common/compress/compress.h
new file mode 100644
index 0000000000000..b504cd38b128b
--- /dev/null
+++ b/fs/smb/common/compress/compress.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2026 Namjae Jeon <linkinjeon@kernel.org>
+ */
+#ifndef _COMMON_SMB_COMPRESS_H
+#define _COMMON_SMB_COMPRESS_H
+
+#include "../smb2pdu.h"
+
+/*
+ * SMB3_COMPRESS_NONE is valid only in chained payload headers. It is never
+ * negotiated as a compression algorithm.
+ */
+static __always_inline bool smb_compress_alg_valid(__le16 alg, bool valid_none)
+{
+ if (alg == SMB3_COMPRESS_NONE)
+ return valid_none;
+
+ return alg == SMB3_COMPRESS_LZ77 || alg == SMB3_COMPRESS_PATTERN;
+}
+
+#endif /* _COMMON_SMB_COMPRESS_H */
diff --git a/fs/smb/client/compress/lz77.c b/fs/smb/common/compress/lz77.c
index 7365d0f97396c..9216d973d8769 100644
--- a/fs/smb/client/compress/lz77.c
+++ b/fs/smb/common/compress/lz77.c
@@ -1,8 +1,10 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2024-2026, SUSE LLC
+ * Copyright (C) 2026 Namjae Jeon <linkinjeon@kernel.org>
*
* Authors: Enzo Matsumiya <ematsumiya@suse.de>
+ * Namjae Jeon <linkinjeon@kernel.org>
*
* Implementation of the LZ77 "plain" compression algorithm, as per MS-XCA spec.
*/
@@ -10,6 +12,8 @@
#include <linux/sizes.h>
#include <linux/count_zeros.h>
#include <linux/unaligned.h>
+#include <linux/module.h>
+#include <linux/overflow.h>
#include "lz77.h"
@@ -32,7 +36,7 @@
*/
#define LZ77_MATCH_MAX_DIST SZ_8K
#define LZ77_HASH_LOG 15
-#define LZ77_HASH_SIZE (1 << LZ77_HASH_LOG)
+#define LZ77_HASH_SIZE BIT(LZ77_HASH_LOG)
#define LZ77_RSTEP_SIZE sizeof(u32)
#define LZ77_MSTEP_SIZE sizeof(u64)
#define LZ77_SKIP_TRIGGER 4
@@ -215,7 +219,8 @@ static __always_inline u32 lz77_hash(const u32 v)
return ((v ^ 0x9E3779B9) * 0x85EBCA6B) >> (32 - LZ77_HASH_LOG);
}
-noinline int lz77_compress(const void *src, const u32 slen, void *dst, u32 *dlen)
+noinline int smb_lz77_compress(const void *src, const u32 slen,
+ void *dst, u32 *dlen)
{
const void *srcp, *rlim, *end, *anchor;
u32 *htable, hash, flag_count = 0;
@@ -223,10 +228,11 @@ noinline int lz77_compress(const void *src, const u32 slen, void *dst, u32 *dlen
long flag = 0;
/* This is probably a bug, so throw a warning. */
- if (WARN_ON_ONCE(*dlen < lz77_compressed_alloc_size(slen)))
+ if (WARN_ON_ONCE(*dlen < smb_lz77_compressed_alloc_size(slen)))
return -EINVAL;
- srcp = anchor = src;
+ srcp = src;
+ anchor = src;
end = srcp + slen; /* absolute end */
rlim = end - LZ77_MSTEP_SIZE; /* read limit (for lz77_match_len()) */
dstp = dst;
@@ -251,7 +257,8 @@ noinline int lz77_compress(const void *src, const u32 slen, void *dst, u32 *dlen
/*
* Main loop.
*
- * @dlen is >= lz77_compressed_alloc_size(), so run without bound-checking @dstp.
+ * @dlen is >= smb_lz77_compressed_alloc_size(), so run without
+ * bound-checking @dstp.
*
* This code was crafted in a way to best utilise fetch-decode-execute CPU flow.
* Any attempt to optimize it, or even organize it, can lead to huge performance loss.
@@ -333,3 +340,122 @@ out:
return -EMSGSIZE;
}
+EXPORT_SYMBOL_GPL(smb_lz77_compress);
+
+static int lz77_decode_match_len(const u8 **src, const u8 *end, u16 token,
+ u8 *nibble, bool *have_nibble, u32 *len)
+{
+ u8 extra;
+
+ *len = (token & 0x7) + 3;
+ if ((token & 0x7) != 0x7)
+ return 0;
+
+ if (!*have_nibble) {
+ if (*src >= end)
+ return -EINVAL;
+ *nibble = *(*src)++;
+ extra = *nibble & 0xf;
+ *have_nibble = true;
+ } else {
+ extra = *nibble >> 4;
+ *have_nibble = false;
+ }
+
+ *len += extra;
+ if (extra == 0xf) {
+ u8 b;
+
+ if (*src >= end)
+ return -EINVAL;
+ b = *(*src)++;
+ if (b != 0xff) {
+ *len += b;
+ } else {
+ u16 w;
+
+ if (end - *src < 2)
+ return -EINVAL;
+ w = get_unaligned_le16(*src);
+ *src += 2;
+ if (w) {
+ *len = w + 3;
+ } else {
+ u32 long_len;
+
+ if (end - *src < 4)
+ return -EINVAL;
+ long_len = get_unaligned_le32(*src);
+ *src += 4;
+ if (check_add_overflow(long_len, 3, len))
+ return -EINVAL;
+ }
+ }
+ }
+
+ return 0;
+}
+
+int smb_lz77_decompress(const void *src, const u32 slen, void *dst,
+ const u32 dlen)
+{
+ const u8 *sp = src, *send = sp + slen;
+ u8 *dp = dst, *dend = dp + dlen;
+ u32 flags = 0;
+ int flag_count = 0;
+ u8 nibble = 0;
+ bool have_nibble = false;
+
+ while (dp < dend) {
+ u32 len, dist;
+ u16 token;
+
+ if (!flag_count) {
+ if (send - sp < 4)
+ return -EINVAL;
+ flags = get_unaligned_le32(sp);
+ sp += 4;
+ flag_count = 32;
+ }
+
+ if (!(flags & 0x80000000)) {
+ if (sp >= send)
+ return -EINVAL;
+ *dp++ = *sp++;
+ flags <<= 1;
+ flag_count--;
+ continue;
+ }
+
+ flags <<= 1;
+ flag_count--;
+
+ if (send - sp < 2)
+ return -EINVAL;
+
+ token = get_unaligned_le16(sp);
+ sp += 2;
+
+ dist = (token >> 3) + 1;
+ if (dist > dp - (u8 *)dst)
+ return -EINVAL;
+
+ if (lz77_decode_match_len(&sp, send, token, &nibble,
+ &have_nibble, &len))
+ return -EINVAL;
+
+ if (len > dend - dp)
+ return -EINVAL;
+
+ while (len--) {
+ *dp = *(dp - dist);
+ dp++;
+ }
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(smb_lz77_decompress);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("SMB plain LZ77 compression");
diff --git a/fs/smb/client/compress/lz77.h b/fs/smb/common/compress/lz77.h
index 4e570846aefa2..e032c0f1b48dd 100644
--- a/fs/smb/client/compress/lz77.h
+++ b/fs/smb/common/compress/lz77.h
@@ -12,7 +12,7 @@
#include <linux/kernel.h>
/**
- * lz77_compressed_alloc_size() - Compute compressed buffer size.
+ * smb_lz77_compressed_alloc_size() - Compute compressed buffer size.
* @size: uncompressed (src) size
*
* Compute allocation size for the compressed buffer based on uncompressed size.
@@ -26,18 +26,21 @@
* Worst case scenario is an all-literal compression, which means:
* metadata bytes = 4 + ((@size / 32) * 4) + 4, or, simplified, (@size >> 3) + 8
*
- * The worst case scenario rarely happens, but such overprovisioning also allows lz77_compress()
- * main loop to run without ever bound checking dst, which is a huge perf improvement, while also
- * being safe when compression goes bad.
+ * The worst case scenario rarely happens, but such overprovisioning also
+ * allows smb_lz77_compress() main loop to run without ever bound checking dst,
+ * which is a huge perf improvement, while also being safe when compression goes
+ * bad.
*
* Return: required (*) allocation size for compressed buffer.
*
- * (*) checked once in the beginning of lz77_compress()
+ * (*) checked once in the beginning of smb_lz77_compress()
*/
-static __always_inline u32 lz77_compressed_alloc_size(const u32 size)
+static __always_inline u32 smb_lz77_compressed_alloc_size(const u32 size)
{
return size + (size >> 3) + 8;
}
-int lz77_compress(const void *src, const u32 slen, void *dst, u32 *dlen);
+int smb_lz77_compress(const void *src, const u32 slen, void *dst, u32 *dlen);
+int smb_lz77_decompress(const void *src, const u32 slen, void *dst,
+ const u32 dlen);
#endif /* _SMB_COMPRESS_LZ77_H */
generated by cgit 1.3-korg (git 2.53.0) at 2026-07-01 13:46:00 +0000