[PATCH 5.18 0102/1095] ksmbd: fix heap-based overflow in set_ntacl_dacl()

Greg Kroah-Hartman
2022-08-15T20:27:08Z

From: Namjae Jeon <linkinjeon@kernel.org>

commit 8f0541186e9ad1b62accc9519cc2b7a7240272a7 upstream.

The testcase use SMB2_SET_INFO_HE command to set a malformed file attribute
under the label `security.NTACL`. SMB2_QUERY_INFO_HE command in testcase
trigger the following overflow.

[ 4712.003781] ==================================================================
[ 4712.003790] BUG: KASAN: slab-out-of-bounds in build_sec_desc+0x842/0x1dd0 [ksmbd]
[ 4712.003807] Write of size 1060 at addr ffff88801e34c068 by task kworker/0:0/4190

[ 4712.003813] CPU: 0 PID: 4190 Comm: kworker/0:0 Not tainted 5.19.0-rc5 #1
[ 4712.003850] Workqueue: ksmbd-io handle_ksmbd_work [ksmbd]
[ 4712.003867] Call Trace:
[ 4712.003870] <TASK>
[ 4712.003873] dump_stack_lvl+0x49/0x5f
[ 4712.003935] print_report.cold+0x5e/0x5cf
[ 4712.003972] ? ksmbd_vfs_get_sd_xattr+0x16d/0x500 [ksmbd]
[ 4712.003984] ? cmp_map_id+0x200/0x200
[ 4712.003988] ? build_sec_desc+0x842/0x1dd0 [ksmbd]
[ 4712.004000] kasan_report+0xaa/0x120
[ 4712.004045] ? build_sec_desc+0x842/0x1dd0 [ksmbd]
[ 4712.004056] kasan_check_range+0x100/0x1e0
[ 4712.004060] memcpy+0x3c/0x60
[ 4712.004064] build_sec_desc+0x842/0x1dd0 [ksmbd]
[ 4712.004076] ? parse_sec_desc+0x580/0x580 [ksmbd]
[ 4712.004088] ? ksmbd_acls_fattr+0x281/0x410 [ksmbd]
[ 4712.004099] smb2_query_info+0xa8f/0x6110 [ksmbd]
[ 4712.004111] ? psi_group_change+0x856/0xd70
[ 4712.004148] ? update_load_avg+0x1c3/0x1af0
[ 4712.004152] ? asym_cpu_capacity_scan+0x5d0/0x5d0
[ 4712.004157] ? xas_load+0x23/0x300
[ 4712.004162] ? smb2_query_dir+0x1530/0x1530 [ksmbd]
[ 4712.004173] ? _raw_spin_lock_bh+0xe0/0xe0
[ 4712.004179] handle_ksmbd_work+0x30e/0x1020 [ksmbd]
[ 4712.004192] process_one_work+0x778/0x11c0
[ 4712.004227] ? _raw_spin_lock_irq+0x8e/0xe0
[ 4712.004231] worker_thread+0x544/0x1180
[ 4712.004234] ? __cpuidle_text_end+0x4/0x4
[ 4712.004239] kthread+0x282/0x320
[ 4712.004243] ? process_one_work+0x11c0/0x11c0
[ 4712.004246] ? kthread_complete_and_exit+0x30/0x30
[ 4712.004282] ret_from_fork+0x1f/0x30

This patch add the buffer validation for security descriptor that is
stored by malformed SMB2_SET_INFO_HE command. and allocate large
response buffer about SMB2_O_INFO_SECURITY file info class.

Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Cc: stable@vger.kernel.org
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-17771
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ksmbd/smb2pdu.c | 39 ++++++++++-----
fs/ksmbd/smbacl.c | 130 +++++++++++++++++++++++++++++++++++------------------
fs/ksmbd/smbacl.h | 2
fs/ksmbd/vfs.c | 5 ++
4 files changed, 119 insertions(+), 57 deletions(-)

--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -535,9 +535,10 @@ int smb2_allocate_rsp_buf(struct ksmbd_w
struct smb2_query_info_req *req;

req = smb2_get_msg(work->request_buf);
- if (req->InfoType == SMB2_O_INFO_FILE &&
- (req->FileInfoClass == FILE_FULL_EA_INFORMATION ||
- req->FileInfoClass == FILE_ALL_INFORMATION))
+ if ((req->InfoType == SMB2_O_INFO_FILE &&
+ (req->FileInfoClass == FILE_FULL_EA_INFORMATION ||
+ req->FileInfoClass == FILE_ALL_INFORMATION)) ||
+ req->InfoType == SMB2_O_INFO_SECURITY)
sz = large_sz;
}

@@ -2974,7 +2975,7 @@ int smb2_open(struct ksmbd_work *work)
goto err_out;

rc = build_sec_desc(user_ns,
- pntsd, NULL,
+ pntsd, NULL, 0,
OWNER_SECINFO |
GROUP_SECINFO |
DACL_SECINFO,
@@ -3819,6 +3820,15 @@ static int verify_info_level(int info_le
return 0;
}

+static int smb2_resp_buf_len(struct ksmbd_work *work, unsigned short hdr2_len)
+{
+ int free_len;
+
+ free_len = (int)(work->response_sz -
+ (get_rfc1002_len(work->response_buf) + 4)) - hdr2_len;
+ return free_len;
+}
+
static int smb2_calc_max_out_buf_len(struct ksmbd_work *work,
unsigned short hdr2_len,
unsigned int out_buf_len)
@@ -3828,9 +3838,7 @@ static int smb2_calc_max_out_buf_len(str
if (out_buf_len > work->conn->vals->max_trans_size)
return -EINVAL;

- free_len = (int)(work->response_sz -
- (get_rfc1002_len(work->response_buf) + 4)) -
- hdr2_len;
+ free_len = smb2_resp_buf_len(work, hdr2_len);
if (free_len < 0)
return -EINVAL;

@@ -5085,10 +5093,10 @@ static int smb2_get_info_sec(struct ksmb
struct smb_ntsd *pntsd = (struct smb_ntsd *)rsp->Buffer, *ppntsd = NULL;
struct smb_fattr fattr = {{0}};
struct inode *inode;
- __u32 secdesclen;
+ __u32 secdesclen = 0;
unsigned int id = KSMBD_NO_FID, pid = KSMBD_NO_FID;
int addition_info = le32_to_cpu(req->AdditionalInformation);
- int rc;
+ int rc = 0, ppntsd_size = 0;

if (addition_info & ~(OWNER_SECINFO | GROUP_SECINFO | DACL_SECINFO |
PROTECTED_DACL_SECINFO |
@@ -5134,11 +5142,14 @@ static int smb2_get_info_sec(struct ksmb

if (test_share_config_flag(work->tcon->share_conf,
KSMBD_SHARE_FLAG_ACL_XATTR))
- ksmbd_vfs_get_sd_xattr(work->conn, user_ns,
- fp->filp->f_path.dentry, &ppntsd);
-
- rc = build_sec_desc(user_ns, pntsd, ppntsd, addition_info,
- &secdesclen, &fattr);
+ ppntsd_size = ksmbd_vfs_get_sd_xattr(work->conn, user_ns,
+ fp->filp->f_path.dentry,
+ &ppntsd);
+
+ /* Check if sd buffer size exceeds response buffer size */
+ if (smb2_resp_buf_len(work, 8) > ppntsd_size)
+ rc = build_sec_desc(user_ns, pntsd, ppntsd, ppntsd_size,
+ addition_info, &secdesclen, &fattr);
posix_acl_release(fattr.cf_acls);
posix_acl_release(fattr.cf_dacls);
kfree(ppntsd);
--- a/fs/ksmbd/smbacl.c
+++ b/fs/ksmbd/smbacl.c
@@ -690,6 +690,7 @@ posix_default_acl:
static void set_ntacl_dacl(struct user_namespace *user_ns,
struct smb_acl *pndacl,
struct smb_acl *nt_dacl,
+ unsigned int aces_size,
const struct smb_sid *pownersid,
const struct smb_sid *pgrpsid,
struct smb_fattr *fattr)
@@ -703,9 +704,19 @@ static void set_ntacl_dacl(struct user_n
if (nt_num_aces) {
ntace = (struct smb_ace *)((char *)nt_dacl + sizeof(struct smb_acl));
for (i = 0; i < nt_num_aces; i++) {
- memcpy((char *)pndace + size, ntace, le16_to_cpu(ntace->size));
- size += le16_to_cpu(ntace->size);
- ntace = (struct smb_ace *)((char *)ntace + le16_to_cpu(ntace->size));
+ unsigned short nt_ace_size;
+
+ if (offsetof(struct smb_ace, access_req) > aces_size)
+ break;
+
+ nt_ace_size = le16_to_cpu(ntace->size);
+ if (nt_ace_size > aces_size)
+ break;
+
+ memcpy((char *)pndace + size, ntace, nt_ace_size);
+ size += nt_ace_size;
+ aces_size -= nt_ace_size;
+ ntace = (struct smb_ace *)((char *)ntace + nt_ace_size);
num_aces++;
}
}
@@ -878,7 +889,7 @@ int parse_sec_desc(struct user_namespace
/* Convert permission bits from mode to equivalent CIFS ACL */
int build_sec_desc(struct user_namespace *user_ns,
struct smb_ntsd *pntsd, struct smb_ntsd *ppntsd,
- int addition_info, __u32 *secdesclen,
+ int ppntsd_size, int addition_info, __u32 *secdesclen,
struct smb_fattr *fattr)
{
int rc = 0;
@@ -938,15 +949,25 @@ int build_sec_desc(struct user_namespace

if (!ppntsd) {
set_mode_dacl(user_ns, dacl_ptr, fattr);
- } else if (!ppntsd->dacloffset) {
- goto out;
} else {
struct smb_acl *ppdacl_ptr;
+ unsigned int dacl_offset = le32_to_cpu(ppntsd->dacloffset);
+ int ppdacl_size, ntacl_size = ppntsd_size - dacl_offset;
+
+ if (!dacl_offset ||
+ (dacl_offset + sizeof(struct smb_acl) > ppntsd_size))
+ goto out;
+
+ ppdacl_ptr = (struct smb_acl *)((char *)ppntsd + dacl_offset);
+ ppdacl_size = le16_to_cpu(ppdacl_ptr->size);
+ if (ppdacl_size > ntacl_size ||
+ ppdacl_size < sizeof(struct smb_acl))
+ goto out;

- ppdacl_ptr = (struct smb_acl *)((char *)ppntsd +
- le32_to_cpu(ppntsd->dacloffset));
set_ntacl_dacl(user_ns, dacl_ptr, ppdacl_ptr,
- nowner_sid_ptr, ngroup_sid_ptr, fattr);
+ ntacl_size - sizeof(struct smb_acl),
+ nowner_sid_ptr, ngroup_sid_ptr,
+ fattr);
}
pntsd->dacloffset = cpu_to_le32(offset);
offset += le16_to_cpu(dacl_ptr->size);
@@ -980,24 +1001,31 @@ int smb_inherit_dacl(struct ksmbd_conn *
struct smb_sid owner_sid, group_sid;
struct dentry *parent = path->dentry->d_parent;
struct user_namespace *user_ns = mnt_user_ns(path->mnt);
- int inherited_flags = 0, flags = 0, i, ace_cnt = 0, nt_size = 0;
- int rc = 0, num_aces, dacloffset, pntsd_type, acl_len;
+ 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;
char *aces_base;
bool is_dir = S_ISDIR(d_inode(path->dentry)->i_mode);

- acl_len = ksmbd_vfs_get_sd_xattr(conn, user_ns,
- parent, &parent_pntsd);
- if (acl_len <= 0)
+ pntsd_size = ksmbd_vfs_get_sd_xattr(conn, user_ns,
+ parent, &parent_pntsd);
+ if (pntsd_size <= 0)
return -ENOENT;
dacloffset = le32_to_cpu(parent_pntsd->dacloffset);
- if (!dacloffset) {
+ if (!dacloffset || (dacloffset + sizeof(struct smb_acl) > pntsd_size)) {
rc = -EINVAL;
goto free_parent_pntsd;
}

parent_pdacl = (struct smb_acl *)((char *)parent_pntsd + dacloffset);
+ acl_len = pntsd_size - dacloffset;
num_aces = le32_to_cpu(parent_pdacl->num_aces);
pntsd_type = le16_to_cpu(parent_pntsd->type);
+ pdacl_size = le16_to_cpu(parent_pdacl->size);
+
+ if (pdacl_size > acl_len || pdacl_size < sizeof(struct smb_acl)) {
+ rc = -EINVAL;
+ goto free_parent_pntsd;
+ }

aces_base = kmalloc(sizeof(struct smb_ace) * num_aces * 2, GFP_KERNEL);
if (!aces_base) {
@@ -1008,11 +1036,23 @@ int smb_inherit_dacl(struct ksmbd_conn *
aces = (struct smb_ace *)aces_base;
parent_aces = (struct smb_ace *)((char *)parent_pdacl +
sizeof(struct smb_acl));
+ aces_size = acl_len - sizeof(struct smb_acl);

if (pntsd_type & DACL_AUTO_INHERITED)
inherited_flags = INHERITED_ACE;

for (i = 0; i < num_aces; i++) {
+ int pace_size;
+
+ if (offsetof(struct smb_ace, access_req) > aces_size)
+ break;
+
+ pace_size = le16_to_cpu(parent_aces->size);
+ if (pace_size > aces_size)
+ break;
+
+ aces_size -= pace_size;
+
flags = parent_aces->flags;
if (!smb_inherit_flags(flags, is_dir))
goto pass;
@@ -1057,8 +1097,7 @@ int smb_inherit_dacl(struct ksmbd_conn *
aces = (struct smb_ace *)((char *)aces + le16_to_cpu(aces->size));
ace_cnt++;
pass:
- parent_aces =
- (struct smb_ace *)((char *)parent_aces + le16_to_cpu(parent_aces->size));
+ parent_aces = (struct smb_ace *)((char *)parent_aces + pace_size);
}

if (nt_size > 0) {
@@ -1153,7 +1192,7 @@ int smb_check_perm_dacl(struct ksmbd_con
struct smb_ntsd *pntsd = NULL;
struct smb_acl *pdacl;
struct posix_acl *posix_acls;
- int rc = 0, acl_size;
+ int rc = 0, pntsd_size, acl_size, aces_size, pdacl_size, dacl_offset;
struct smb_sid sid;
int granted = le32_to_cpu(*pdaccess & ~FILE_MAXIMAL_ACCESS_LE);
struct smb_ace *ace;
@@ -1162,37 +1201,33 @@ int smb_check_perm_dacl(struct ksmbd_con
struct smb_ace *others_ace = NULL;
struct posix_acl_entry *pa_entry;
unsigned int sid_type = SIDOWNER;
- char *end_of_acl;
+ unsigned short ace_size;

ksmbd_debug(SMB, "check permission using windows acl\n");
- acl_size = ksmbd_vfs_get_sd_xattr(conn, user_ns,
- path->dentry, &pntsd);
- if (acl_size <= 0 || !pntsd || !pntsd->dacloffset) {
- kfree(pntsd);
- return 0;
- }
+ pntsd_size = ksmbd_vfs_get_sd_xattr(conn, user_ns,
+ path->dentry, &pntsd);
+ if (pntsd_size <= 0 || !pntsd)
+ goto err_out;
+
+ dacl_offset = le32_to_cpu(pntsd->dacloffset);
+ if (!dacl_offset ||
+ (dacl_offset + sizeof(struct smb_acl) > pntsd_size))
+ goto err_out;

pdacl = (struct smb_acl *)((char *)pntsd + le32_to_cpu(pntsd->dacloffset));
- end_of_acl = ((char *)pntsd) + acl_size;
- if (end_of_acl <= (char *)pdacl) {
- kfree(pntsd);
- return 0;
- }
+ acl_size = pntsd_size - dacl_offset;
+ pdacl_size = le16_to_cpu(pdacl->size);

- if (end_of_acl < (char *)pdacl + le16_to_cpu(pdacl->size) ||
- le16_to_cpu(pdacl->size) < sizeof(struct smb_acl)) {
- kfree(pntsd);
- return 0;
- }
+ if (pdacl_size > acl_size || pdacl_size < sizeof(struct smb_acl))
+ goto err_out;

if (!pdacl->num_aces) {
- if (!(le16_to_cpu(pdacl->size) - sizeof(struct smb_acl)) &&
+ if (!(pdacl_size - sizeof(struct smb_acl)) &&
*pdaccess & ~(FILE_READ_CONTROL_LE | FILE_WRITE_DAC_LE)) {
rc = -EACCES;
goto err_out;
}
- kfree(pntsd);
- return 0;
+ goto err_out;
}

if (*pdaccess & FILE_MAXIMAL_ACCESS_LE) {
@@ -1200,11 +1235,16 @@ int smb_check_perm_dacl(struct ksmbd_con
DELETE;

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++) {
+ if (offsetof(struct smb_ace, access_req) > aces_size)
+ break;
+ ace_size = le16_to_cpu(ace->size);
+ if (ace_size > aces_size)
+ break;
+ aces_size -= ace_size;
granted |= le32_to_cpu(ace->access_req);
ace = (struct smb_ace *)((char *)ace + le16_to_cpu(ace->size));
- if (end_of_acl < (char *)ace)
- goto err_out;
}

if (!pdacl->num_aces)
@@ -1216,7 +1256,15 @@ int smb_check_perm_dacl(struct ksmbd_con
id_to_sid(uid, sid_type, &sid);

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++) {
+ if (offsetof(struct smb_ace, access_req) > aces_size)
+ break;
+ ace_size = le16_to_cpu(ace->size);
+ if (ace_size > aces_size)
+ break;
+ aces_size -= ace_size;
+
if (!compare_sids(&sid, &ace->sid) ||
!compare_sids(&sid_unix_NFS_mode, &ace->sid)) {
found = 1;
@@ -1226,8 +1274,6 @@ int smb_check_perm_dacl(struct ksmbd_con
others_ace = ace;

ace = (struct smb_ace *)((char *)ace + le16_to_cpu(ace->size));
- if (end_of_acl < (char *)ace)
- goto err_out;
}

if (*pdaccess & FILE_MAXIMAL_ACCESS_LE && found) {
--- a/fs/ksmbd/smbacl.h
+++ b/fs/ksmbd/smbacl.h
@@ -193,7 +193,7 @@ struct posix_acl_state {
int parse_sec_desc(struct user_namespace *user_ns, struct smb_ntsd *pntsd,
int acl_len, struct smb_fattr *fattr);
int build_sec_desc(struct user_namespace *user_ns, struct smb_ntsd *pntsd,
- struct smb_ntsd *ppntsd, int addition_info,
+ 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);
void free_acl_state(struct posix_acl_state *state);
--- a/fs/ksmbd/vfs.c
+++ b/fs/ksmbd/vfs.c
@@ -1540,6 +1540,11 @@ int ksmbd_vfs_get_sd_xattr(struct ksmbd_
}

*pntsd = acl.sd_buf;
+ if (acl.sd_size < sizeof(struct smb_ntsd)) {
+ pr_err("sd size is invalid\n");
+ goto out_free;
+ }
+
(*pntsd)->osidoffset = cpu_to_le32(le32_to_cpu((*pntsd)->osidoffset) -
NDR_NTSD_OFFSETOF);
(*pntsd)->gsidoffset = cpu_to_le32(le32_to_cpu((*pntsd)->gsidoffset) -