[PATCH 6.0 0007/1073] cifs: fix oops during encryption

Greg Kroah-Hartman
2022-12-28T14:56:51Z

From: Paulo Alcantara <pc@cjr.nz>

[ Upstream commit f7f291e14dde32a07b1f0aa06921d28f875a7b54 ]

When running xfstests against Azure the following oops occurred on an
arm64 system

Unable to handle kernel write to read-only memory at virtual address
ffff0001221cf000
Mem abort info:
ESR = 0x9600004f
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x0f: level 3 permission fault
Data abort info:
ISV = 0, ISS = 0x0000004f
CM = 0, WnR = 1
swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000000294f3000
[ffff0001221cf000] pgd=18000001ffff8003, p4d=18000001ffff8003,
pud=18000001ff82e003, pmd=18000001ff71d003, pte=00600001221cf787
Internal error: Oops: 9600004f [#1] PREEMPT SMP
...
pstate: 80000005 (Nzcv daif -PAN -UAO -TCO BTYPE=--)
pc : __memcpy+0x40/0x230
lr : scatterwalk_copychunks+0xe0/0x200
sp : ffff800014e92de0
x29: ffff800014e92de0 x28: ffff000114f9de80 x27: 0000000000000008
x26: 0000000000000008 x25: ffff800014e92e78 x24: 0000000000000008
x23: 0000000000000001 x22: 0000040000000000 x21: ffff000000000000
x20: 0000000000000001 x19: ffff0001037c4488 x18: 0000000000000014
x17: 235e1c0d6efa9661 x16: a435f9576b6edd6c x15: 0000000000000058
x14: 0000000000000001 x13: 0000000000000008 x12: ffff000114f2e590
x11: ffffffffffffffff x10: 0000040000000000 x9 : ffff8000105c3580
x8 : 2e9413b10000001a x7 : 534b4410fb86b005 x6 : 534b4410fb86b005
x5 : ffff0001221cf008 x4 : ffff0001037c4490 x3 : 0000000000000001
x2 : 0000000000000008 x1 : ffff0001037c4488 x0 : ffff0001221cf000
Call trace:
__memcpy+0x40/0x230
scatterwalk_map_and_copy+0x98/0x100
crypto_ccm_encrypt+0x150/0x180
crypto_aead_encrypt+0x2c/0x40
crypt_message+0x750/0x880
smb3_init_transform_rq+0x298/0x340
smb_send_rqst.part.11+0xd8/0x180
smb_send_rqst+0x3c/0x100
compound_send_recv+0x534/0xbc0
smb2_query_info_compound+0x32c/0x440
smb2_set_ea+0x438/0x4c0
cifs_xattr_set+0x5d4/0x7c0

This is because in scatterwalk_copychunks(), we attempted to write to
a buffer (@sign) that was allocated in the stack (vmalloc area) by
crypt_message() and thus accessing its remaining 8 (x2) bytes ended up
crossing a page boundary.

To simply fix it, we could just pass @sign kmalloc'd from
crypt_message() and then we're done. Luckily, we don't seem to pass
any other vmalloc'd buffers in smb_rqst::rq_iov...

Instead, let's map the correct pages and offsets from vmalloc buffers
as well in cifs_sg_set_buf() and then avoiding such oopses.

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/cifs/cifsglob.h | 68 +++++++++++++++++++++
fs/cifs/cifsproto.h | 4 +-
fs/cifs/misc.c | 4 +-
fs/cifs/smb2ops.c | 143 +++++++++++++++++++++-----------------------
4 files changed, 140 insertions(+), 79 deletions(-)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 333022028bb0..b52dca800eac 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -13,6 +13,8 @@
#include <linux/in6.h>
#include <linux/inet.h>
#include <linux/slab.h>
+#include <linux/scatterlist.h>
+#include <linux/mm.h>
#include <linux/mempool.h>
#include <linux/workqueue.h>
#include <linux/utsname.h>
@@ -2147,4 +2149,70 @@ static inline void move_cifs_info_to_smb2(struct smb2_file_all_info *dst, const
dst->FileNameLength = src->FileNameLength;
}

+static inline unsigned int cifs_get_num_sgs(const struct smb_rqst *rqst,
+ int num_rqst,
+ const u8 *sig)
+{
+ unsigned int len, skip;
+ unsigned int nents = 0;
+ unsigned long addr;
+ int i, j;
+
+ /* Assumes the first rqst has a transform header as the first iov.
+ * I.e.
+ * rqst[0].rq_iov[0] is transform header
+ * rqst[0].rq_iov[1+] data to be encrypted/decrypted
+ * rqst[1+].rq_iov[0+] data to be encrypted/decrypted
+ */
+ for (i = 0; i < num_rqst; i++) {
+ /*
+ * The first rqst has a transform header where the
+ * first 20 bytes are not part of the encrypted blob.
+ */
+ for (j = 0; j < rqst[i].rq_nvec; j++) {
+ struct kvec *iov = &rqst[i].rq_iov[j];
+
+ skip = (i == 0) && (j == 0) ? 20 : 0;
+ addr = (unsigned long)iov->iov_base + skip;
+ if (unlikely(is_vmalloc_addr((void *)addr))) {
+ len = iov->iov_len - skip;
+ nents += DIV_ROUND_UP(offset_in_page(addr) + len,
+ PAGE_SIZE);
+ } else {
+ nents++;
+ }
+ }
+ nents += rqst[i].rq_npages;
+ }
+ nents += DIV_ROUND_UP(offset_in_page(sig) + SMB2_SIGNATURE_SIZE, PAGE_SIZE);
+ return nents;
+}
+
+/* We can not use the normal sg_set_buf() as we will sometimes pass a
+ * stack object as buf.
+ */
+static inline struct scatterlist *cifs_sg_set_buf(struct scatterlist *sg,
+ const void *buf,
+ unsigned int buflen)
+{
+ unsigned long addr = (unsigned long)buf;
+ unsigned int off = offset_in_page(addr);
+
+ addr &= PAGE_MASK;
+ if (unlikely(is_vmalloc_addr((void *)addr))) {
+ do {
+ unsigned int len = min_t(unsigned int, buflen, PAGE_SIZE - off);
+
+ sg_set_page(sg++, vmalloc_to_page((void *)addr), len, off);
+
+ off = 0;
+ addr += PAGE_SIZE;
+ buflen -= len;
+ } while (buflen);
+ } else {
+ sg_set_page(sg++, virt_to_page(addr), buflen, off);
+ }
+ return sg;
+}
+
#endif /* _CIFS_GLOB_H */
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 372ff64a285b..edf6f18ec8b7 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -601,8 +601,8 @@ int cifs_alloc_hash(const char *name, struct crypto_shash **shash,
struct sdesc **sdesc);
void cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc);

-extern void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
- unsigned int *len, unsigned int *offset);
+void rqst_page_get_length(const struct smb_rqst *rqst, unsigned int page,
+ unsigned int *len, unsigned int *offset);
struct cifs_chan *
cifs_ses_find_chan(struct cifs_ses *ses, struct TCP_Server_Info *server);
int cifs_try_adding_channels(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses);
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 3a117e2269a0..1efb5ca9fd80 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -1137,8 +1137,8 @@ cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc)
* @len: Where to store the length for this page:
* @offset: Where to store the offset for this page
*/
-void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
- unsigned int *len, unsigned int *offset)
+void rqst_page_get_length(const struct smb_rqst *rqst, unsigned int page,
+ unsigned int *len, unsigned int *offset)
{
*len = rqst->rq_pagesz;
*offset = (page == 0) ? rqst->rq_offset : 0;
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index d454164e7f48..74052b51655e 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -4182,69 +4182,82 @@ fill_transform_hdr(struct smb2_transform_hdr *tr_hdr, unsigned int orig_len,
memcpy(&tr_hdr->SessionId, &shdr->SessionId, 8);
}

-/* We can not use the normal sg_set_buf() as we will sometimes pass a
- * stack object as buf.
- */
-static inline void smb2_sg_set_buf(struct scatterlist *sg, const void *buf,
- unsigned int buflen)
+static void *smb2_aead_req_alloc(struct crypto_aead *tfm, const struct smb_rqst *rqst,
+ int num_rqst, const u8 *sig, u8 **iv,
+ struct aead_request **req, struct scatterlist **sgl,
+ unsigned int *num_sgs)
{
- void *addr;
- /*
- * VMAP_STACK (at least) puts stack into the vmalloc address space
- */
- if (is_vmalloc_addr(buf))
- addr = vmalloc_to_page(buf);
- else
- addr = virt_to_page(buf);
- sg_set_page(sg, addr, buflen, offset_in_page(buf));
+ unsigned int req_size = sizeof(**req) + crypto_aead_reqsize(tfm);
+ unsigned int iv_size = crypto_aead_ivsize(tfm);
+ unsigned int len;
+ u8 *p;
+
+ *num_sgs = cifs_get_num_sgs(rqst, num_rqst, sig);
+
+ len = iv_size;
+ len += crypto_aead_alignmask(tfm) & ~(crypto_tfm_ctx_alignment() - 1);
+ len = ALIGN(len, crypto_tfm_ctx_alignment());
+ len += req_size;
+ len = ALIGN(len, __alignof__(struct scatterlist));
+ len += *num_sgs * sizeof(**sgl);
+
+ p = kmalloc(len, GFP_ATOMIC);
+ if (!p)
+ return NULL;
+
+ *iv = (u8 *)PTR_ALIGN(p, crypto_aead_alignmask(tfm) + 1);
+ *req = (struct aead_request *)PTR_ALIGN(*iv + iv_size,
+ crypto_tfm_ctx_alignment());
+ *sgl = (struct scatterlist *)PTR_ALIGN((u8 *)*req + req_size,
+ __alignof__(struct scatterlist));
+ return p;
}

-/* Assumes the first rqst has a transform header as the first iov.
- * I.e.
- * rqst[0].rq_iov[0] is transform header
- * rqst[0].rq_iov[1+] data to be encrypted/decrypted
- * rqst[1+].rq_iov[0+] data to be encrypted/decrypted
- */
-static struct scatterlist *
-init_sg(int num_rqst, struct smb_rqst *rqst, u8 *sign)
+static void *smb2_get_aead_req(struct crypto_aead *tfm, const struct smb_rqst *rqst,
+ int num_rqst, const u8 *sig, u8 **iv,
+ struct aead_request **req, struct scatterlist **sgl)
{
- unsigned int sg_len;
+ unsigned int off, len, skip;
struct scatterlist *sg;
- unsigned int i;
- unsigned int j;
- unsigned int idx = 0;
- int skip;
-
- sg_len = 1;
- for (i = 0; i < num_rqst; i++)
- sg_len += rqst[i].rq_nvec + rqst[i].rq_npages;
+ unsigned int num_sgs;
+ unsigned long addr;
+ int i, j;
+ void *p;

- sg = kmalloc_array(sg_len, sizeof(struct scatterlist), GFP_KERNEL);
- if (!sg)
+ p = smb2_aead_req_alloc(tfm, rqst, num_rqst, sig, iv, req, sgl, &num_sgs);
+ if (!p)
return NULL;

- sg_init_table(sg, sg_len);
+ sg_init_table(*sgl, num_sgs);
+ sg = *sgl;
+
+ /* Assumes the first rqst has a transform header as the first iov.
+ * I.e.
+ * rqst[0].rq_iov[0] is transform header
+ * rqst[0].rq_iov[1+] data to be encrypted/decrypted
+ * rqst[1+].rq_iov[0+] data to be encrypted/decrypted
+ */
for (i = 0; i < num_rqst; i++) {
+ /*
+ * The first rqst has a transform header where the
+ * first 20 bytes are not part of the encrypted blob.
+ */
for (j = 0; j < rqst[i].rq_nvec; j++) {
- /*
- * The first rqst has a transform header where the
- * first 20 bytes are not part of the encrypted blob
- */
- skip = (i == 0) && (j == 0) ? 20 : 0;
- smb2_sg_set_buf(&sg[idx++],
- rqst[i].rq_iov[j].iov_base + skip,
- rqst[i].rq_iov[j].iov_len - skip);
- }
+ struct kvec *iov = &rqst[i].rq_iov[j];

+ skip = (i == 0) && (j == 0) ? 20 : 0;
+ addr = (unsigned long)iov->iov_base + skip;
+ len = iov->iov_len - skip;
+ sg = cifs_sg_set_buf(sg, (void *)addr, len);
+ }
for (j = 0; j < rqst[i].rq_npages; j++) {
- unsigned int len, offset;
-
- rqst_page_get_length(&rqst[i], j, &len, &offset);
- sg_set_page(&sg[idx++], rqst[i].rq_pages[j], len, offset);
+ rqst_page_get_length(&rqst[i], j, &len, &off);
+ sg_set_page(sg++, rqst[i].rq_pages[j], len, off);
}
}
- smb2_sg_set_buf(&sg[idx], sign, SMB2_SIGNATURE_SIZE);
- return sg;
+ cifs_sg_set_buf(sg, sig, SMB2_SIGNATURE_SIZE);
+
+ return p;
}

static int
@@ -4290,11 +4303,11 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst,
u8 sign[SMB2_SIGNATURE_SIZE] = {};
u8 key[SMB3_ENC_DEC_KEY_SIZE];
struct aead_request *req;
- char *iv;
- unsigned int iv_len;
+ u8 *iv;
DECLARE_CRYPTO_WAIT(wait);
struct crypto_aead *tfm;
unsigned int crypt_len = le32_to_cpu(tr_hdr->OriginalMessageSize);
+ void *creq;

rc = smb2_get_enc_key(server, le64_to_cpu(tr_hdr->SessionId), enc, key);
if (rc) {
@@ -4329,32 +4342,15 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst,
return rc;
}

- req = aead_request_alloc(tfm, GFP_KERNEL);
- if (!req) {
- cifs_server_dbg(VFS, "%s: Failed to alloc aead request\n", __func__);
+ creq = smb2_get_aead_req(tfm, rqst, num_rqst, sign, &iv, &req, &sg);
+ if (unlikely(!creq))
return -ENOMEM;
- }

if (!enc) {
memcpy(sign, &tr_hdr->Signature, SMB2_SIGNATURE_SIZE);
crypt_len += SMB2_SIGNATURE_SIZE;
}

- sg = init_sg(num_rqst, rqst, sign);
- if (!sg) {
- cifs_server_dbg(VFS, "%s: Failed to init sg\n", __func__);
- rc = -ENOMEM;
- goto free_req;
- }
-
- iv_len = crypto_aead_ivsize(tfm);
- iv = kzalloc(iv_len, GFP_KERNEL);
- if (!iv) {
- cifs_server_dbg(VFS, "%s: Failed to alloc iv\n", __func__);
- rc = -ENOMEM;
- goto free_sg;
- }
-
if ((server->cipher_type == SMB2_ENCRYPTION_AES128_GCM) ||
(server->cipher_type == SMB2_ENCRYPTION_AES256_GCM))
memcpy(iv, (char *)tr_hdr->Nonce, SMB3_AES_GCM_NONCE);
@@ -4363,6 +4359,7 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst,
memcpy(iv + 1, (char *)tr_hdr->Nonce, SMB3_AES_CCM_NONCE);
}

+ aead_request_set_tfm(req, tfm);
aead_request_set_crypt(req, sg, sg, crypt_len, iv);
aead_request_set_ad(req, assoc_data_len);

@@ -4375,11 +4372,7 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst,
if (!rc && enc)
memcpy(&tr_hdr->Signature, sign, SMB2_SIGNATURE_SIZE);

- kfree_sensitive(iv);
-free_sg:
- kfree_sensitive(sg);
-free_req:
- kfree_sensitive(req);
+ kfree_sensitive(creq);
return rc;
}

--
2.35.1