From: Hyunchul Lee <hyc.lee@gmail.com>
To: linux-cifs@vger.kernel.org
Cc: Hyunchul Lee <hyc.lee@gmail.com>,
Ronnie Sahlberg <ronniesahlberg@gmail.com>,
Ralph Boehme <slow@samba.org>, Steve French <smfrench@gmail.com>,
Namjae Jeon <linkinjeon@kernel.org>
Subject: [PATCH v4] ksmbd: add buffer validation for SMB2_CREATE_CONTEXT
Date: Fri, 24 Sep 2021 22:22:22 +0900 [thread overview]
Message-ID: <20210924132222.914168-2-hyc.lee@gmail.com> (raw)
In-Reply-To: <20210924132222.914168-1-hyc.lee@gmail.com>
Add buffer validation for SMB2_CREATE_CONTEXT.
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Ralph Boehme <slow@samba.org>
Cc: Steve French <smfrench@gmail.com>
Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
Changes from v2:
- check struct create_context's fields more in smb2_find_context_vals()
Changes from v3:
- fix possible overflow when accessing create_context structure in
smb2_find_context_vals()
- fix possible overflow when accessing smb_ace structure in parse_dacl()
fs/ksmbd/oplock.c | 41 +++++++++++++++++++++++++++++++----------
fs/ksmbd/smb2pdu.c | 25 ++++++++++++++++++++++++-
fs/ksmbd/smbacl.c | 21 +++++++++++++++++++--
3 files changed, 74 insertions(+), 13 deletions(-)
diff --git a/fs/ksmbd/oplock.c b/fs/ksmbd/oplock.c
index 16b6236d1bd2..f9dae6ef2115 100644
--- a/fs/ksmbd/oplock.c
+++ b/fs/ksmbd/oplock.c
@@ -1451,26 +1451,47 @@ 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 create_context *cc;
unsigned int next = 0;
char *name;
struct smb2_create_req *req = (struct smb2_create_req *)open_req;
+ unsigned int remain_len, name_off, name_len, value_off, value_len,
+ cc_len;
- data_offset = (char *)req + 4 + le32_to_cpu(req->CreateContextsOffset);
- cc = (struct create_context *)data_offset;
+ /*
+ * CreateContextsOffset and CreateContextsLength are guaranteed to
+ * be valid because of ksmbd_smb2_check_message().
+ */
+ cc = (struct create_context *)((char *)req + 4 +
+ le32_to_cpu(req->CreateContextsOffset));
+ remain_len = le32_to_cpu(req->CreateContextsLength);
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 (remain_len < offsetof(struct create_context, Buffer))
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);
+ cc_len = next ? next : remain_len;
+
+ if ((next & 0x7) != 0 ||
+ next > remain_len ||
+ name_off != offsetof(struct create_context, Buffer) ||
+ name_len < 4 ||
+ name_off + name_len > cc_len ||
+ (value_off & 0x7) != 0 ||
+ (value_off && (value_off < name_off + name_len)) ||
+ ((u64)value_off + value_len > cc_len))
+ return ERR_PTR(-EINVAL);
+
+ name = (char *)cc + name_off;
+ if (memcmp(name, tag, name_len) == 0)
+ return cc;
+
+ remain_len -= next;
} while (next != 0);
return NULL;
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index bb39b18a6673..6220f1f7322e 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -2427,6 +2427,10 @@ 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);
}
@@ -2621,6 +2625,12 @@ 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;
@@ -2659,6 +2669,12 @@ 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);
@@ -3049,9 +3065,16 @@ 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..bd792db32623 100644
--- a/fs/ksmbd/smbacl.c
+++ b/fs/ksmbd/smbacl.c
@@ -380,7 +380,7 @@ static void parse_dacl(struct user_namespace *user_ns,
{
int i, ret;
int num_aces = 0;
- int acl_size;
+ unsigned int acl_size;
char *acl_base;
struct smb_ace **ppace;
struct posix_acl_entry *cf_pace, *cf_pdace;
@@ -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;
@@ -431,8 +431,22 @@ static void parse_dacl(struct user_namespace *user_ns,
* user/group/other have no permissions
*/
for (i = 0; i < num_aces; ++i) {
+ if (end_of_acl - acl_base < acl_size)
+ break;
+
ppace[i] = (struct smb_ace *)(acl_base + acl_size);
acl_base = (char *)ppace[i];
+ acl_size = offsetof(struct smb_ace, sid) +
+ offsetof(struct smb_sid, sub_auth);
+
+ if (end_of_acl - acl_base < acl_size ||
+ ppace[i]->sid.num_subauth > SID_MAX_SUB_AUTHORITIES ||
+ (end_of_acl - acl_base <
+ acl_size + sizeof(__le32) * ppace[i]->sid.num_subauth) ||
+ (le16_to_cpu(ppace[i]->size) <
+ acl_size + sizeof(__le32) * ppace[i]->sid.num_subauth))
+ break;
+
acl_size = le16_to_cpu(ppace[i]->size);
ppace[i]->access_req =
smb_map_generic_desired_access(ppace[i]->access_req);
@@ -807,6 +821,9 @@ 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 +
--
2.25.1
prev parent reply other threads:[~2021-09-24 13:31 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-24 13:22 [PATCH v3] ksmbd: use LOOKUP_BENEATH to prevent the out of share access Hyunchul Lee
2021-09-24 13:22 ` Hyunchul Lee [this message]
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