Hi Hyunchul,
patch looks excellent, few more nitpicks below.
Am 22.09.21 um 03:26 schrieb Hyunchul Lee:
Add buffer validation for SMB2_CREATE_CONTEXT.
Cc: Ronnie Sahlberg <ronniesahlberg@xxxxxxxxx>
Cc: Ralph Boehme <slow@xxxxxxxxx>
Cc: Steve French <smfrench@xxxxxxxxx>
Signed-off-by: Hyunchul Lee <hyc.lee@xxxxxxxxx>
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
---
Changes from v2:
- check struct create_context's fields more in smb2_find_context_vals
(suggested by Ralph Boehme).
fs/ksmbd/oplock.c | 34 ++++++++++++++++++++++++----------
fs/ksmbd/smb2pdu.c | 25 ++++++++++++++++++++++++-
fs/ksmbd/smbacl.c | 9 ++++++++-
3 files changed, 56 insertions(+), 12 deletions(-)
diff --git a/fs/ksmbd/oplock.c b/fs/ksmbd/oplock.c
index 16b6236d1bd2..8f743913b1cf 100644
--- a/fs/ksmbd/oplock.c
+++ b/fs/ksmbd/oplock.c
@@ -1451,26 +1451,40 @@ struct lease_ctx_info *parse_lease_state(void
*open_req)
*/
struct create_context *smb2_find_context_vals(void *open_req, const
char *tag)
{
- char *data_offset;
+ struct smb2_create_req *req = (struct smb2_create_req *)open_req;
struct create_context *cc;
- unsigned int next = 0;
+ char *data_offset, *data_end;
char *name;
- struct smb2_create_req *req = (struct smb2_create_req *)open_req;
this line is only moved, not changed. Can we remove this change from the
diff?
+ unsigned int next = 0;
+ unsigned int name_off, name_len, value_off, value_len;
data_offset = (char *)req + 4 +
le32_to_cpu(req->CreateContextsOffset);
+ data_end = data_offset + le32_to_cpu(req->CreateContextsLength);
do we need overflow checks here? At least on 32-bit arch this could
easily overflow.
cc = (struct create_context *)data_offset;
do {
- int val;
-
cc = (struct create_context *)((char *)cc + next);
- name = le16_to_cpu(cc->NameOffset) + (char *)cc;
- val = le16_to_cpu(cc->NameLength);
- if (val < 4)
+ if ((char *)cc + offsetof(struct create_context, Buffer) >
+ data_end)
return ERR_PTR(-EINVAL);
- if (memcmp(name, tag, val) == 0)
- return cc;
next = le32_to_cpu(cc->Next);
+ name_off = le16_to_cpu(cc->NameOffset);
+ name_len = le16_to_cpu(cc->NameLength);
+ value_off = le16_to_cpu(cc->DataOffset);
+ value_len = le32_to_cpu(cc->DataLength);
same here: possible overflow checks needed?
+
+ if ((next & 0x7) != 0 ||
+ name_off != 16 ||
+ name_len < 4 ||
+ (char *)cc + name_off + name_len > data_end ||
+ (value_off & 0x7) != 0 ||
+ (value_off && value_off < name_off + name_len) ||
I guess this must be
(value_off && (value_off < name_off + name_len)) ||
+ (char *)cc + value_off + value_len > data_end)
+ return ERR_PTR(-EINVAL);
+
+ name = (char *)cc + name_off;
+ if (memcmp(name, tag, name_len) == 0)
+ return cc;
} while (next != 0);
return NULL;
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index c86164dc70bb..976490bfd93c 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -2377,6 +2377,10 @@ static int smb2_create_sd_buffer(struct
ksmbd_work *work,
ksmbd_debug(SMB,
"Set ACLs using SMB2_CREATE_SD_BUFFER context\n");
sd_buf = (struct create_sd_buf_req *)context;
+ if (le16_to_cpu(context->DataOffset) +
+ le32_to_cpu(context->DataLength) <
+ sizeof(struct create_sd_buf_req))
+ return -EINVAL;
return set_info_sec(work->conn, work->tcon, path, &sd_buf->ntsd,
le32_to_cpu(sd_buf->ccontext.DataLength), true);
}
@@ -2577,6 +2581,12 @@ int smb2_open(struct ksmbd_work *work)
goto err_out1;
} else if (context) {
ea_buf = (struct create_ea_buf_req *)context;
+ if (le16_to_cpu(context->DataOffset) +
+ le32_to_cpu(context->DataLength) <
+ sizeof(struct create_ea_buf_req)) {
+ rc = -EINVAL;
+ goto err_out1;
+ }
if (req->CreateOptions & FILE_NO_EA_KNOWLEDGE_LE) {
rsp->hdr.Status = STATUS_ACCESS_DENIED;
rc = -EACCES;
@@ -2615,6 +2625,12 @@ int smb2_open(struct ksmbd_work *work)
} else if (context) {
struct create_posix *posix =
(struct create_posix *)context;
+ if (le16_to_cpu(context->DataOffset) +
+ le32_to_cpu(context->DataLength) <
+ sizeof(struct create_posix)) {
+ rc = -EINVAL;
+ goto err_out1;
+ }
ksmbd_debug(SMB, "get posix context\n");
posix_mode = le32_to_cpu(posix->Mode);
@@ -3019,9 +3035,16 @@ int smb2_open(struct ksmbd_work *work)
rc = PTR_ERR(az_req);
goto err_out;
} else if (az_req) {
- loff_t alloc_size = le64_to_cpu(az_req->AllocationSize);
+ loff_t alloc_size;
int err;
+ if (le16_to_cpu(az_req->ccontext.DataOffset) +
+ le32_to_cpu(az_req->ccontext.DataLength) <
+ sizeof(struct create_alloc_size_req)) {
+ rc = -EINVAL;
+ goto err_out;
+ }
+ alloc_size = le64_to_cpu(az_req->AllocationSize);
ksmbd_debug(SMB,
"request smb2 create allocate size : %llu\n",
alloc_size);
diff --git a/fs/ksmbd/smbacl.c b/fs/ksmbd/smbacl.c
index 0a95cdec8c80..f67567e1e178 100644
--- a/fs/ksmbd/smbacl.c
+++ b/fs/ksmbd/smbacl.c
@@ -392,7 +392,7 @@ static void parse_dacl(struct user_namespace
*user_ns,
return;
/* validate that we do not go past end of acl */
- if (end_of_acl <= (char *)pdacl ||
+ if (end_of_acl < (char *)pdacl + sizeof(struct smb_acl) ||
end_of_acl < (char *)pdacl + le16_to_cpu(pdacl->size)) {
pr_err("ACL too small to parse DACL\n");
return;
@@ -434,6 +434,10 @@ static void parse_dacl(struct user_namespace
*user_ns,
ppace[i] = (struct smb_ace *)(acl_base + acl_size);
acl_base = (char *)ppace[i];
acl_size = le16_to_cpu(ppace[i]->size);
overflow check needed?
+
+ if (acl_base + acl_size > end_of_acl)
+ break;
+
ppace[i]->access_req =
smb_map_generic_desired_access(ppace[i]->access_req);
@@ -807,6 +811,9 @@ int parse_sec_desc(struct user_namespace *user_ns,
struct smb_ntsd *pntsd,
if (!pntsd)
return -EIO;
+ if (acl_len < sizeof(struct smb_ntsd))
+ return -EINVAL;
+
owner_sid_ptr = (struct smb_sid *)((char *)pntsd +
le32_to_cpu(pntsd->osidoffset));
group_sid_ptr = (struct smb_sid *)((char *)pntsd +
Thanks!
-slow
