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ksmbd: validate SID in parent security descriptor during ACL inheritance

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Introduce smb_validate_ntsd_sid() helper to safely validate Owner SID
and Group SID inside the NT Security Descriptor (smb_ntsd) retrieved
from the parent directory.

Cc: stable@vger.kernel.org
Signed-off-by: Junyi Liu <moss80199@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Junyi Liu 2026-05-19 16:12:04 +09:00 committed by Steve French
parent 3515503322
commit 69f030cf95
1 changed files with 50 additions and 16 deletions
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66
fs/smb/server/smbacl.c
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@ -1096,6 +1096,40 @@ static int smb_append_inherited_ace(struct smb_ace **ace, int *nt_size,
return 0;
}
static int smb_validate_ntsd_sid(struct smb_ntsd *pntsd, size_t pntsd_size,
unsigned int sid_offset, struct smb_sid **sid,
size_t *sid_size)
{
size_t sid_end;
*sid = NULL;
*sid_size = 0;
if (!sid_offset)
return 0;
if (sid_offset < sizeof(struct smb_ntsd) ||
check_add_overflow(sid_offset, (size_t)CIFS_SID_BASE_SIZE,
&sid_end) ||
sid_end > pntsd_size)
return -EINVAL;
*sid = (struct smb_sid *)((char *)pntsd + sid_offset);
if ((*sid)->num_subauth > SID_MAX_SUB_AUTHORITIES)
return -EINVAL;
if (check_add_overflow((size_t)CIFS_SID_BASE_SIZE,
sizeof(__le32) * (size_t)(*sid)->num_subauth,
&sid_end))
return -EINVAL;
if (sid_offset > pntsd_size || sid_end > pntsd_size - sid_offset)
return -EINVAL;
*sid_size = sid_end;
return 0;
}
int smb_inherit_dacl(struct ksmbd_conn *conn,
const struct path *path,
unsigned int uid, unsigned int gid)
@ -1108,28 +1142,28 @@ 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, nt_size = 0, pdacl_size;
int rc = 0, pntsd_type, pntsd_size, acl_len, aces_size;
int rc = 0, pntsd_type, ppntsd_size, acl_len, aces_size;
unsigned int dacloffset;
size_t dacl_struct_end;
u16 num_aces, ace_cnt = 0;
char *aces_base;
bool is_dir = S_ISDIR(d_inode(path->dentry)->i_mode);
pntsd_size = ksmbd_vfs_get_sd_xattr(conn, idmap,
ppntsd_size = ksmbd_vfs_get_sd_xattr(conn, idmap,
parent, &parent_pntsd);
if (pntsd_size <= 0)
if (ppntsd_size <= 0)
return -ENOENT;
dacloffset = le32_to_cpu(parent_pntsd->dacloffset);
if (!dacloffset ||
check_add_overflow(dacloffset, sizeof(struct smb_acl), &dacl_struct_end) ||
dacl_struct_end > (size_t)pntsd_size) {
dacl_struct_end > (size_t)ppntsd_size) {
rc = -EINVAL;
goto free_parent_pntsd;
}
parent_pdacl = (struct smb_acl *)((char *)parent_pntsd + dacloffset);
acl_len = pntsd_size - dacloffset;
acl_len = ppntsd_size - dacloffset;
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);
@ -1243,19 +1277,19 @@ int smb_inherit_dacl(struct ksmbd_conn *conn,
struct smb_ntsd *pntsd;
struct smb_acl *pdacl;
struct smb_sid *powner_sid = NULL, *pgroup_sid = NULL;
int powner_sid_size = 0, pgroup_sid_size = 0, pntsd_size;
size_t powner_sid_size = 0, pgroup_sid_size = 0, pntsd_size;
size_t pntsd_alloc_size;
if (parent_pntsd->osidoffset) {
powner_sid = (struct smb_sid *)((char *)parent_pntsd +
le32_to_cpu(parent_pntsd->osidoffset));
powner_sid_size = 1 + 1 + 6 + (powner_sid->num_subauth * 4);
}
if (parent_pntsd->gsidoffset) {
pgroup_sid = (struct smb_sid *)((char *)parent_pntsd +
le32_to_cpu(parent_pntsd->gsidoffset));
pgroup_sid_size = 1 + 1 + 6 + (pgroup_sid->num_subauth * 4);
}
rc = smb_validate_ntsd_sid(parent_pntsd, ppntsd_size,
le32_to_cpu(parent_pntsd->osidoffset),
&powner_sid, &powner_sid_size);
if (rc)
goto free_aces_base;
rc = smb_validate_ntsd_sid(parent_pntsd, ppntsd_size,
le32_to_cpu(parent_pntsd->gsidoffset),
&pgroup_sid, &pgroup_sid_size);
if (rc)
goto free_aces_base;
if (check_add_overflow(sizeof(struct smb_ntsd),
(size_t)powner_sid_size,