[PATCH 1/4] smb: common: change the data type of num_aces to le16

[PATCH 1/4] smb: common: change the data type of num_aces to le16

[Namjae Jeon]

2.4.5 in [MS-DTYP].pdf describe the data type of num_aces as le16.

AceCount (2 bytes): An unsigned 16-bit integer that specifies the count
of the number of ACE records in the ACL.

Change it to le16 and add reserved field to smb_acl struct.

Reported-by: Igor Leite Ladessa <igor-ladessa@hotmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
 fs/smb/client/cifsacl.c | 26 +++++++++++++-------------
 fs/smb/common/smbacl.h  |  3 ++-
 fs/smb/server/smbacl.c  | 27 ++++++++++++++-------------
 fs/smb/server/smbacl.h  |  2 +-
 4 files changed, 30 insertions(+), 28 deletions(-)

diff --git a/fs/smb/client/cifsacl.c b/fs/smb/client/cifsacl.c
index 699a3f76d083..7d953208046a 100644
--- a/fs/smb/client/cifsacl.c
+++ b/fs/smb/client/cifsacl.c
@@ -763,7 +763,7 @@ static void parse_dacl(struct smb_acl *pdacl, char *end_of_acl,
 		       struct cifs_fattr *fattr, bool mode_from_special_sid)
 {
 	int i;
-	int num_aces = 0;
+	u16 num_aces = 0;
 	int acl_size;
 	char *acl_base;
 	struct smb_ace **ppace;
@@ -785,7 +785,7 @@ static void parse_dacl(struct smb_acl *pdacl, char *end_of_acl,
 
 	cifs_dbg(NOISY, "DACL revision %d size %d num aces %d\n",
 		 le16_to_cpu(pdacl->revision), le16_to_cpu(pdacl->size),
-		 le32_to_cpu(pdacl->num_aces));
+		 le16_to_cpu(pdacl->num_aces));
 
 	/* reset rwx permissions for user/group/other.
 	   Also, if num_aces is 0 i.e. DACL has no ACEs,
@@ -795,7 +795,7 @@ static void parse_dacl(struct smb_acl *pdacl, char *end_of_acl,
 	acl_base = (char *)pdacl;
 	acl_size = sizeof(struct smb_acl);
 
-	num_aces = le32_to_cpu(pdacl->num_aces);
+	num_aces = le16_to_cpu(pdacl->num_aces);
 	if (num_aces > 0) {
 		umode_t denied_mode = 0;
 
@@ -937,12 +937,12 @@ unsigned int setup_special_user_owner_ACE(struct smb_ace *pntace)
 static void populate_new_aces(char *nacl_base,
 		struct smb_sid *pownersid,
 		struct smb_sid *pgrpsid,
-		__u64 *pnmode, u32 *pnum_aces, u16 *pnsize,
+		__u64 *pnmode, u16 *pnum_aces, u16 *pnsize,
 		bool modefromsid,
 		bool posix)
 {
 	__u64 nmode;
-	u32 num_aces = 0;
+	u16 num_aces = 0;
 	u16 nsize = 0;
 	__u64 user_mode;
 	__u64 group_mode;
@@ -1050,7 +1050,7 @@ static __u16 replace_sids_and_copy_aces(struct smb_acl *pdacl, struct smb_acl *p
 	u16 size = 0;
 	struct smb_ace *pntace = NULL;
 	char *acl_base = NULL;
-	u32 src_num_aces = 0;
+	u16 src_num_aces = 0;
 	u16 nsize = 0;
 	struct smb_ace *pnntace = NULL;
 	char *nacl_base = NULL;
@@ -1058,7 +1058,7 @@ static __u16 replace_sids_and_copy_aces(struct smb_acl *pdacl, struct smb_acl *p
 
 	acl_base = (char *)pdacl;
 	size = sizeof(struct smb_acl);
-	src_num_aces = le32_to_cpu(pdacl->num_aces);
+	src_num_aces = le16_to_cpu(pdacl->num_aces);
 
 	nacl_base = (char *)pndacl;
 	nsize = sizeof(struct smb_acl);
@@ -1090,11 +1090,11 @@ static int set_chmod_dacl(struct smb_acl *pdacl, struct smb_acl *pndacl,
 	u16 size = 0;
 	struct smb_ace *pntace = NULL;
 	char *acl_base = NULL;
-	u32 src_num_aces = 0;
+	u16 src_num_aces = 0;
 	u16 nsize = 0;
 	struct smb_ace *pnntace = NULL;
 	char *nacl_base = NULL;
-	u32 num_aces = 0;
+	u16 num_aces = 0;
 	bool new_aces_set = false;
 
 	/* Assuming that pndacl and pnmode are never NULL */
@@ -1112,7 +1112,7 @@ static int set_chmod_dacl(struct smb_acl *pdacl, struct smb_acl *pndacl,
 
 	acl_base = (char *)pdacl;
 	size = sizeof(struct smb_acl);
-	src_num_aces = le32_to_cpu(pdacl->num_aces);
+	src_num_aces = le16_to_cpu(pdacl->num_aces);
 
 	/* Retain old ACEs which we can retain */
 	for (i = 0; i < src_num_aces; ++i) {
@@ -1158,7 +1158,7 @@ static int set_chmod_dacl(struct smb_acl *pdacl, struct smb_acl *pndacl,
 	}
 
 finalize_dacl:
-	pndacl->num_aces = cpu_to_le32(num_aces);
+	pndacl->num_aces = cpu_to_le16(num_aces);
 	pndacl->size = cpu_to_le16(nsize);
 
 	return 0;
@@ -1293,7 +1293,7 @@ static int build_sec_desc(struct smb_ntsd *pntsd, struct smb_ntsd *pnntsd,
 			dacloffset ? dacl_ptr->revision : cpu_to_le16(ACL_REVISION);
 
 		ndacl_ptr->size = cpu_to_le16(0);
-		ndacl_ptr->num_aces = cpu_to_le32(0);
+		ndacl_ptr->num_aces = cpu_to_le16(0);
 
 		rc = set_chmod_dacl(dacl_ptr, ndacl_ptr, owner_sid_ptr, group_sid_ptr,
 				    pnmode, mode_from_sid, posix);
@@ -1653,7 +1653,7 @@ id_mode_to_cifs_acl(struct inode *inode, const char *path, __u64 *pnmode,
 			dacl_ptr = (struct smb_acl *)((char *)pntsd + dacloffset);
 			if (mode_from_sid)
 				nsecdesclen +=
-					le32_to_cpu(dacl_ptr->num_aces) * sizeof(struct smb_ace);
+					le16_to_cpu(dacl_ptr->num_aces) * sizeof(struct smb_ace);
 			else /* cifsacl */
 				nsecdesclen += le16_to_cpu(dacl_ptr->size);
 		}
diff --git a/fs/smb/common/smbacl.h b/fs/smb/common/smbacl.h
index 6a60698fc6f0..a624ec9e4a14 100644
--- a/fs/smb/common/smbacl.h
+++ b/fs/smb/common/smbacl.h
@@ -107,7 +107,8 @@ struct smb_sid {
 struct smb_acl {
 	__le16 revision; /* revision level */
 	__le16 size;
-	__le32 num_aces;
+	__le16 num_aces;
+	__le16 reserved;
 } __attribute__((packed));
 
 struct smb_ace {
diff --git a/fs/smb/server/smbacl.c b/fs/smb/server/smbacl.c
index d39d3e553366..f820d0759c3c 100644
--- a/fs/smb/server/smbacl.c
+++ b/fs/smb/server/smbacl.c
@@ -333,7 +333,7 @@ void posix_state_to_acl(struct posix_acl_state *state,
 	pace->e_perm = state->other.allow;
 }
 
-int init_acl_state(struct posix_acl_state *state, int cnt)
+int init_acl_state(struct posix_acl_state *state, u16 cnt)
 {
 	int alloc;
 
@@ -368,7 +368,7 @@ static void parse_dacl(struct mnt_idmap *idmap,
 		       struct smb_fattr *fattr)
 {
 	int i, ret;
-	int num_aces = 0;
+	u16 num_aces = 0;
 	unsigned int acl_size;
 	char *acl_base;
 	struct smb_ace **ppace;
@@ -389,12 +389,12 @@ static void parse_dacl(struct mnt_idmap *idmap,
 
 	ksmbd_debug(SMB, "DACL revision %d size %d num aces %d\n",
 		    le16_to_cpu(pdacl->revision), le16_to_cpu(pdacl->size),
-		    le32_to_cpu(pdacl->num_aces));
+		    le16_to_cpu(pdacl->num_aces));
 
 	acl_base = (char *)pdacl;
 	acl_size = sizeof(struct smb_acl);
 
-	num_aces = le32_to_cpu(pdacl->num_aces);
+	num_aces = le16_to_cpu(pdacl->num_aces);
 	if (num_aces <= 0)
 		return;
 
@@ -580,7 +580,7 @@ static void parse_dacl(struct mnt_idmap *idmap,
 
 static void set_posix_acl_entries_dacl(struct mnt_idmap *idmap,
 				       struct smb_ace *pndace,
-				       struct smb_fattr *fattr, u32 *num_aces,
+				       struct smb_fattr *fattr, u16 *num_aces,
 				       u16 *size, u32 nt_aces_num)
 {
 	struct posix_acl_entry *pace;
@@ -701,7 +701,7 @@ static void set_ntacl_dacl(struct mnt_idmap *idmap,
 			   struct smb_fattr *fattr)
 {
 	struct smb_ace *ntace, *pndace;
-	int nt_num_aces = le32_to_cpu(nt_dacl->num_aces), num_aces = 0;
+	u16 nt_num_aces = le32_to_cpu(nt_dacl->num_aces), num_aces = 0;
 	unsigned short size = 0;
 	int i;
 
@@ -728,7 +728,7 @@ static void set_ntacl_dacl(struct mnt_idmap *idmap,
 
 	set_posix_acl_entries_dacl(idmap, pndace, fattr,
 				   &num_aces, &size, nt_num_aces);
-	pndacl->num_aces = cpu_to_le32(num_aces);
+	pndacl->num_aces = cpu_to_le16(num_aces);
 	pndacl->size = cpu_to_le16(le16_to_cpu(pndacl->size) + size);
 }
 
@@ -736,7 +736,7 @@ static void set_mode_dacl(struct mnt_idmap *idmap,
 			  struct smb_acl *pndacl, struct smb_fattr *fattr)
 {
 	struct smb_ace *pace, *pndace;
-	u32 num_aces = 0;
+	u16 num_aces = 0;
 	u16 size = 0, ace_size = 0;
 	uid_t uid;
 	const struct smb_sid *sid;
@@ -792,7 +792,7 @@ static void set_mode_dacl(struct mnt_idmap *idmap,
 				 fattr->cf_mode, 0007);
 
 out:
-	pndacl->num_aces = cpu_to_le32(num_aces);
+	pndacl->num_aces = cpu_to_le16(num_aces);
 	pndacl->size = cpu_to_le16(le16_to_cpu(pndacl->size) + size);
 }
 
@@ -1007,7 +1007,8 @@ int smb_inherit_dacl(struct ksmbd_conn *conn,
 	struct dentry *parent = path->dentry->d_parent;
 	struct mnt_idmap *idmap = mnt_idmap(path->mnt);
 	int inherited_flags = 0, flags = 0, i, ace_cnt = 0, nt_size = 0, pdacl_size;
-	int rc = 0, num_aces, dacloffset, pntsd_type, pntsd_size, acl_len, aces_size;
+	int rc = 0, dacloffset, pntsd_type, pntsd_size, acl_len, aces_size;
+	u16 num_aces;
 	char *aces_base;
 	bool is_dir = S_ISDIR(d_inode(path->dentry)->i_mode);
 
@@ -1023,7 +1024,7 @@ int smb_inherit_dacl(struct ksmbd_conn *conn,
 
 	parent_pdacl = (struct smb_acl *)((char *)parent_pntsd + dacloffset);
 	acl_len = pntsd_size - dacloffset;
-	num_aces = le32_to_cpu(parent_pdacl->num_aces);
+	num_aces = le16_to_cpu(parent_pdacl->num_aces);
 	pntsd_type = le16_to_cpu(parent_pntsd->type);
 	pdacl_size = le16_to_cpu(parent_pdacl->size);
 
@@ -1264,7 +1265,7 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
 
 		ace = (struct smb_ace *)((char *)pdacl + sizeof(struct smb_acl));
 		aces_size = acl_size - sizeof(struct smb_acl);
-		for (i = 0; i < le32_to_cpu(pdacl->num_aces); i++) {
+		for (i = 0; i < le16_to_cpu(pdacl->num_aces); i++) {
 			if (offsetof(struct smb_ace, access_req) > aces_size)
 				break;
 			ace_size = le16_to_cpu(ace->size);
@@ -1285,7 +1286,7 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
 
 	ace = (struct smb_ace *)((char *)pdacl + sizeof(struct smb_acl));
 	aces_size = acl_size - sizeof(struct smb_acl);
-	for (i = 0; i < le32_to_cpu(pdacl->num_aces); i++) {
+	for (i = 0; i < le16_to_cpu(pdacl->num_aces); i++) {
 		if (offsetof(struct smb_ace, access_req) > aces_size)
 			break;
 		ace_size = le16_to_cpu(ace->size);
diff --git a/fs/smb/server/smbacl.h b/fs/smb/server/smbacl.h
index 24ce576fc292..355adaee39b8 100644
--- a/fs/smb/server/smbacl.h
+++ b/fs/smb/server/smbacl.h
@@ -86,7 +86,7 @@ int parse_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
 int build_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
 		   struct smb_ntsd *ppntsd, int ppntsd_size, int addition_info,
 		   __u32 *secdesclen, struct smb_fattr *fattr);
-int init_acl_state(struct posix_acl_state *state, int cnt);
+int init_acl_state(struct posix_acl_state *state, u16 cnt);
 void free_acl_state(struct posix_acl_state *state);
 void posix_state_to_acl(struct posix_acl_state *state,
 			struct posix_acl_entry *pace);
-- 
2.25.1

[PATCH 2/4] ksmbd: fix incorrect validation for num_aces field of smb_acl

[Namjae Jeon]

parse_dcal() validate num_aces to allocate posix_ace_state_array.

if (num_aces > ULONG_MAX / sizeof(struct smb_ace *))

It is an incorrect validation that we can create an array of size ULONG_MAX.
smb_acl has ->size field to calculate actual number of aces in request buffer
size. Use this to check invalid num_aces.

Reported-by: Igor Leite Ladessa <igor-ladessa@hotmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
 fs/smb/server/smbacl.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/smb/server/smbacl.c b/fs/smb/server/smbacl.c
index f820d0759c3c..410a4b10c91d 100644
--- a/fs/smb/server/smbacl.c
+++ b/fs/smb/server/smbacl.c
@@ -398,7 +398,9 @@ static void parse_dacl(struct mnt_idmap *idmap,
 	if (num_aces <= 0)
 		return;
 
-	if (num_aces > ULONG_MAX / sizeof(struct smb_ace *))
+	if (num_aces > (pdacl->size - sizeof(struct smb_acl)) /
+			(offsetof(struct smb_ace, sid) +
+			 offsetof(struct smb_sid, sub_auth) + sizeof(__le16)))
 		return;
 
 	ret = init_acl_state(&acl_state, num_aces);
@@ -432,6 +434,7 @@ static void parse_dacl(struct mnt_idmap *idmap,
 			offsetof(struct smb_sid, sub_auth);
 
 		if (end_of_acl - acl_base < acl_size ||
+		    ppace[i]->sid.num_subauth == 0 ||
 		    ppace[i]->sid.num_subauth > SID_MAX_SUB_AUTHORITIES ||
 		    (end_of_acl - acl_base <
 		     acl_size + sizeof(__le32) * ppace[i]->sid.num_subauth) ||
-- 
2.25.1

[PATCH 3/4] cifs: fix incorrect validation for num_aces field of smb_acl

[Namjae Jeon]

parse_dcal() validate num_aces to allocate ace array.

f (num_aces > ULONG_MAX / sizeof(struct smb_ace *))

It is an incorrect validation that we can create an array of size ULONG_MAX.
smb_acl has ->size field to calculate actual number of aces in response buffer
size. Use this to check invalid num_aces.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
 fs/smb/client/cifsacl.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/smb/client/cifsacl.c b/fs/smb/client/cifsacl.c
index 7d953208046a..6b29a01a6e56 100644
--- a/fs/smb/client/cifsacl.c
+++ b/fs/smb/client/cifsacl.c
@@ -778,7 +778,8 @@ static void parse_dacl(struct smb_acl *pdacl, char *end_of_acl,
 	}
 
 	/* validate that we do not go past end of acl */
-	if (end_of_acl < (char *)pdacl + le16_to_cpu(pdacl->size)) {
+	if (end_of_acl < (char *)pdacl + sizeof(struct smb_acl) ||
+	    end_of_acl < (char *)pdacl + le16_to_cpu(pdacl->size)) {
 		cifs_dbg(VFS, "ACL too small to parse DACL\n");
 		return;
 	}
@@ -799,8 +800,11 @@ static void parse_dacl(struct smb_acl *pdacl, char *end_of_acl,
 	if (num_aces > 0) {
 		umode_t denied_mode = 0;
 
-		if (num_aces > ULONG_MAX / sizeof(struct smb_ace *))
+		if (num_aces > (pdacl->size - sizeof(struct smb_acl)) /
+				(offsetof(struct smb_ace, sid) +
+				 offsetof(struct smb_sid, sub_auth) + sizeof(__le16)))
 			return;
+
 		ppace = kmalloc_array(num_aces, sizeof(struct smb_ace *),
 				      GFP_KERNEL);
 		if (!ppace)
-- 
2.25.1

[PATCH 4/4] cifs: add validation check for the fields in smb_aces

[Namjae Jeon]

cifs.ko is missing validation check when accessing smb_aces.
This patch add validation check for the fields in smb_aces.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
 fs/smb/client/cifsacl.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/fs/smb/client/cifsacl.c b/fs/smb/client/cifsacl.c
index 6b29a01a6e56..5c511b28dd77 100644
--- a/fs/smb/client/cifsacl.c
+++ b/fs/smb/client/cifsacl.c
@@ -811,7 +811,23 @@ static void parse_dacl(struct smb_acl *pdacl, char *end_of_acl,
 			return;
 
 		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 == 0 ||
+			    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;
+
 #ifdef CONFIG_CIFS_DEBUG2
 			dump_ace(ppace[i], end_of_acl);
 #endif
@@ -855,7 +871,6 @@ static void parse_dacl(struct smb_acl *pdacl, char *end_of_acl,
 				(void *)ppace[i],
 				sizeof(struct smb_ace)); */
 
-			acl_base = (char *)ppace[i];
 			acl_size = le16_to_cpu(ppace[i]->size);
 		}
 
-- 
2.25.1