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 --- v2: - add missing fixes and stable tags. v3: - change goto statement with break for smb_ace buffer validation check.

fs/ksmbd/smb2pdu.c | 37 ++++++++----- fs/ksmbd/smbacl.c | 130 ++++++++++++++++++++++++++++++--------------- fs/ksmbd/smbacl.h | 2 +- fs/ksmbd/vfs.c | 5 ++ 4 files changed, 118 insertions(+), 56 deletions(-)

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c index ea47aa0262ee..c2c25e50cec6 100644 --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -535,9 +535,10 @@ int smb2_allocate_rsp_buf(struct ksmbd_work *work) 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; }

@@ -2988,7 +2989,7 @@ 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, @@ -3833,6 +3834,15 @@ static int verify_info_level(int info_level) 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) @@ -3842,9 +3852,7 @@ static int smb2_calc_max_out_buf_len(struct ksmbd_work *work, 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;

@@ -5110,7 +5118,7 @@ static int smb2_get_info_sec(struct ksmbd_work *work, __u32 secdesclen; 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 | @@ -5156,11 +5164,14 @@ static int smb2_get_info_sec(struct ksmbd_work *work,

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); diff --git a/fs/ksmbd/smbacl.c b/fs/ksmbd/smbacl.c index 38f23bf981ac..e9cd96f0bc44 100644 --- a/fs/ksmbd/smbacl.c +++ b/fs/ksmbd/smbacl.c @@ -690,6 +690,7 @@ static void set_posix_acl_entries_dacl(struct user_namespace *user_ns, 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_namespace *user_ns, 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 *user_ns, struct smb_ntsd *pntsd, /* 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 *user_ns,

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 *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 *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 *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_conn *conn, struct path *path, 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_conn *conn, struct path *path, 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) + goto err_out; + + dacl_offset = le32_to_cpu(pntsd->dacloffset); + if (!pntsd || !pntsd->dacloffset || + (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_conn *conn, struct path *path, 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_conn *conn, struct path *path, 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_conn *conn, struct path *path, 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) { diff --git a/fs/ksmbd/smbacl.h b/fs/ksmbd/smbacl.h index 811af3309429..fcb2c83f2992 100644 --- 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); diff --git a/fs/ksmbd/vfs.c b/fs/ksmbd/vfs.c index 4f75b1436eab..7af7e0853f06 100644 --- a/fs/ksmbd/vfs.c +++ b/fs/ksmbd/vfs.c @@ -1539,6 +1539,11 @@ int ksmbd_vfs_get_sd_xattr(struct ksmbd_conn *conn, }

*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) -