2021-09-22 11:31 GMT+09:00, Namjae Jeon <linkinjeon@xxxxxxxxxx>: > 2021-09-21 23:23 GMT+09:00, Tom Talpey <tom@xxxxxxxxxx>: >> On 9/18/2021 10:13 PM, Namjae Jeon wrote: >>> Add buffer validation in smb2_set_info. >>> >>> Cc: Ronnie Sahlberg <ronniesahlberg@xxxxxxxxx> >>> Cc: Ralph Böhme <slow@xxxxxxxxx> >>> Cc: Steve French <smfrench@xxxxxxxxx> >>> Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx> >>> --- >>> fs/ksmbd/smb2pdu.c | 113 +++++++++++++++++++++++++++++++++++---------- >>> fs/ksmbd/smb2pdu.h | 9 ++++ >>> 2 files changed, 97 insertions(+), 25 deletions(-) >>> >>> diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c >>> index 46e0275a77a8..7763f69e1ae8 100644 >>> --- a/fs/ksmbd/smb2pdu.c >>> +++ b/fs/ksmbd/smb2pdu.c >>> @@ -2107,17 +2107,23 @@ static noinline int create_smb2_pipe(struct >>> ksmbd_work *work) >>> * smb2_set_ea() - handler for setting extended attributes using set >>> * info command >>> * @eabuf: set info command buffer >>> + * @buf_len: set info command buffer length >>> * @path: dentry path for get ea >>> * >>> * Return: 0 on success, otherwise error >>> */ >>> -static int smb2_set_ea(struct smb2_ea_info *eabuf, struct path *path) >>> +static int smb2_set_ea(struct smb2_ea_info *eabuf, unsigned int >>> buf_len, >>> + struct path *path) >>> { >>> struct user_namespace *user_ns = mnt_user_ns(path->mnt); >>> char *attr_name = NULL, *value; >>> int rc = 0; >>> int next = 0; >>> >>> + if (buf_len < sizeof(struct smb2_ea_info) + eabuf->EaNameLength + >>> + le16_to_cpu(eabuf->EaValueLength)) >>> + return -EINVAL; >> >> How certain is it that EaNameLength and EaValueLength are sane? One >> might imagine a forged packet with various combinations of invalid >> values, which arithmetically satisfy the above check... > Sorry, I didn't fully understand what you pointed out. Could you > please elaborate more ? Maybe, You are saying we need the below check? @@ -2577,6 +2581,12 @@ 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; + } This check is in create context patch. (https://marc.info/?l=linux-cifs&m=163227401430586&w=2) > >> >>> + >>> attr_name = kmalloc(XATTR_NAME_MAX + 1, GFP_KERNEL); >>> if (!attr_name) >>> return -ENOMEM; >>> @@ -2181,7 +2187,13 @@ static int smb2_set_ea(struct smb2_ea_info >>> *eabuf, >>> struct path *path) >>> >>> next: >>> next = le32_to_cpu(eabuf->NextEntryOffset); >>> + if (next == 0 || buf_len < next) >>> + break; >>> + buf_len -= next; >> >> Because buf_len is unsigned int and next is signed int, these compares >> are risky. I think "next" should also be unsigned, but if not, testing >> it for negative values before these checks is important. >> >> In the many changes below, buf_len is passed in as signed. Those should >> be consistent with the same criteria. It pays to be paranoid everywhere! > Okay, I will update it on next version. >> >> Tom. >> >>> eabuf = (struct smb2_ea_info *)((char *)eabuf + next); >>> + if (next < eabuf->EaNameLength + le16_to_cpu(eabuf->EaValueLength)) >>> + break; >>> + >>> } while (next != 0); >>> >>> kfree(attr_name); >>> @@ -2790,7 +2802,9 @@ int smb2_open(struct ksmbd_work *work) >>> created = true; >>> user_ns = mnt_user_ns(path.mnt); >>> if (ea_buf) { >>> - rc = smb2_set_ea(&ea_buf->ea, &path); >>> + rc = smb2_set_ea(&ea_buf->ea, >>> + le32_to_cpu(ea_buf->ccontext.DataLength), >>> + &path); >> >> Again, is DataLength verified? > This field is checked by create context validation patch. > See: https://marc.info/?l=linux-cifs&m=163227401430586&w=2 >> >>> if (rc == -EOPNOTSUPP) >>> rc = 0; >>> else if (rc) >>> @@ -5375,7 +5389,7 @@ static int smb2_rename(struct ksmbd_work *work, >>> static int smb2_create_link(struct ksmbd_work *work, >>> struct ksmbd_share_config *share, >>> struct smb2_file_link_info *file_info, >>> - struct file *filp, >>> + int buf_len, struct file *filp, >>> struct nls_table *local_nls) >>> { >>> char *link_name = NULL, *target_name = NULL, *pathname = NULL; >>> @@ -5383,6 +5397,10 @@ static int smb2_create_link(struct ksmbd_work >>> *work, >>> bool file_present = true; >>> int rc; >>> >>> + if (buf_len < sizeof(struct smb2_file_link_info) + >>> + le32_to_cpu(file_info->FileNameLength)) >>> + return -EINVAL; >>> + >>> ksmbd_debug(SMB, "setting FILE_LINK_INFORMATION\n"); >>> pathname = kmalloc(PATH_MAX, GFP_KERNEL); >>> if (!pathname) >>> @@ -5442,7 +5460,7 @@ static int smb2_create_link(struct ksmbd_work >>> *work, >>> static int set_file_basic_info(struct ksmbd_file *fp, char *buf, >>> struct ksmbd_share_config *share) >>> { >>> - struct smb2_file_all_info *file_info; >>> + struct smb2_file_basic_info *file_info; >>> struct iattr attrs; >>> struct timespec64 ctime; >>> struct file *filp; >>> @@ -5453,7 +5471,7 @@ static int set_file_basic_info(struct ksmbd_file >>> *fp, char *buf, >>> if (!(fp->daccess & FILE_WRITE_ATTRIBUTES_LE)) >>> return -EACCES; >>> >>> - file_info = (struct smb2_file_all_info *)buf; >>> + file_info = (struct smb2_file_basic_info *)buf; >>> attrs.ia_valid = 0; >>> filp = fp->filp; >>> inode = file_inode(filp); >>> @@ -5619,7 +5637,8 @@ static int set_end_of_file_info(struct ksmbd_work >>> *work, struct ksmbd_file *fp, >>> } >>> >>> static int set_rename_info(struct ksmbd_work *work, struct ksmbd_file >>> *fp, >>> - char *buf) >>> + struct smb2_file_rename_info *rename_info, >>> + int buf_len) >>> { >>> struct user_namespace *user_ns; >>> struct ksmbd_file *parent_fp; >>> @@ -5632,6 +5651,10 @@ static int set_rename_info(struct ksmbd_work >>> *work, >>> struct ksmbd_file *fp, >>> return -EACCES; >>> } >>> >>> + if (buf_len < sizeof(struct smb2_file_rename_info) + >>> + le32_to_cpu(rename_info->FileNameLength)) >>> + return -EINVAL; >>> + >>> user_ns = file_mnt_user_ns(fp->filp); >>> if (ksmbd_stream_fd(fp)) >>> goto next; >>> @@ -5654,8 +5677,7 @@ static int set_rename_info(struct ksmbd_work >>> *work, >>> struct ksmbd_file *fp, >>> } >>> } >>> next: >>> - return smb2_rename(work, fp, user_ns, >>> - (struct smb2_file_rename_info *)buf, >>> + return smb2_rename(work, fp, user_ns, rename_info, >>> work->sess->conn->local_nls); >>> } >>> >>> @@ -5741,40 +5763,71 @@ static int set_file_mode_info(struct ksmbd_file >>> *fp, char *buf) >>> * TODO: need to implement an error handling for >>> STATUS_INFO_LENGTH_MISMATCH >>> */ >>> static int smb2_set_info_file(struct ksmbd_work *work, struct >>> ksmbd_file >>> *fp, >>> - int info_class, char *buf, >>> + struct smb2_set_info_req *req, >>> struct ksmbd_share_config *share) >>> { >>> - switch (info_class) { >>> + int buf_len = le32_to_cpu(req->BufferLength); >>> + >>> + switch (req->FileInfoClass) { >>> case FILE_BASIC_INFORMATION: >>> - return set_file_basic_info(fp, buf, share); >>> + { >>> + if (buf_len < sizeof(struct smb2_file_basic_info)) >>> + return -EINVAL; >>> >>> + return set_file_basic_info(fp, req->Buffer, share); >>> + } >>> case FILE_ALLOCATION_INFORMATION: >>> - return set_file_allocation_info(work, fp, buf); >>> + { >>> + if (buf_len < sizeof(struct smb2_file_alloc_info)) >>> + return -EINVAL; >>> >>> + return set_file_allocation_info(work, fp, req->Buffer); >>> + } >>> case FILE_END_OF_FILE_INFORMATION: >>> - return set_end_of_file_info(work, fp, buf); >>> + { >>> + if (buf_len < sizeof(struct smb2_file_eof_info)) >>> + return -EINVAL; >>> >>> + return set_end_of_file_info(work, fp, req->Buffer); >>> + } >>> case FILE_RENAME_INFORMATION: >>> + { >>> if (!test_tree_conn_flag(work->tcon, KSMBD_TREE_CONN_FLAG_WRITABLE)) >>> { >>> ksmbd_debug(SMB, >>> "User does not have write permission\n"); >>> return -EACCES; >>> } >>> - return set_rename_info(work, fp, buf); >>> >>> + if (buf_len < sizeof(struct smb2_file_rename_info)) >>> + return -EINVAL; >>> + >>> + return set_rename_info(work, fp, >>> + (struct smb2_file_rename_info *)req->Buffer, >>> + buf_len); >>> + } >>> case FILE_LINK_INFORMATION: >>> + { >>> + if (buf_len < sizeof(struct smb2_file_link_info)) >>> + return -EINVAL; >>> + >>> return smb2_create_link(work, work->tcon->share_conf, >>> - (struct smb2_file_link_info *)buf, fp->filp, >>> + (struct smb2_file_link_info *)req->Buffer, >>> + buf_len, fp->filp, >>> work->sess->conn->local_nls); >>> - >>> + } >>> case FILE_DISPOSITION_INFORMATION: >>> + { >>> if (!test_tree_conn_flag(work->tcon, KSMBD_TREE_CONN_FLAG_WRITABLE)) >>> { >>> ksmbd_debug(SMB, >>> "User does not have write permission\n"); >>> return -EACCES; >>> } >>> - return set_file_disposition_info(fp, buf); >>> >>> + if (buf_len < sizeof(struct smb2_file_disposition_info)) >>> + return -EINVAL; >>> + >>> + return set_file_disposition_info(fp, req->Buffer); >>> + } >>> case FILE_FULL_EA_INFORMATION: >>> { >>> if (!(fp->daccess & FILE_WRITE_EA_LE)) { >>> @@ -5783,18 +5836,29 @@ static int smb2_set_info_file(struct ksmbd_work >>> *work, struct ksmbd_file *fp, >>> return -EACCES; >>> } >>> >>> - return smb2_set_ea((struct smb2_ea_info *)buf, >>> - &fp->filp->f_path); >>> - } >>> + if (buf_len < sizeof(struct smb2_ea_info)) >>> + return -EINVAL; >>> >>> + return smb2_set_ea((struct smb2_ea_info *)req->Buffer, >>> + buf_len, &fp->filp->f_path); >>> + } >>> case FILE_POSITION_INFORMATION: >>> - return set_file_position_info(fp, buf); >>> + { >>> + if (buf_len < sizeof(struct smb2_file_pos_info)) >>> + return -EINVAL; >>> >>> + return set_file_position_info(fp, req->Buffer); >>> + } >>> case FILE_MODE_INFORMATION: >>> - return set_file_mode_info(fp, buf); >>> + { >>> + if (buf_len < sizeof(struct smb2_file_mode_info)) >>> + return -EINVAL; >>> + >>> + return set_file_mode_info(fp, req->Buffer); >>> + } >>> } >>> >>> - pr_err("Unimplemented Fileinfoclass :%d\n", info_class); >>> + pr_err("Unimplemented Fileinfoclass :%d\n", req->FileInfoClass); >>> return -EOPNOTSUPP; >>> } >>> >>> @@ -5855,8 +5919,7 @@ int smb2_set_info(struct ksmbd_work *work) >>> switch (req->InfoType) { >>> case SMB2_O_INFO_FILE: >>> ksmbd_debug(SMB, "GOT SMB2_O_INFO_FILE\n"); >>> - rc = smb2_set_info_file(work, fp, req->FileInfoClass, >>> - req->Buffer, work->tcon->share_conf); >>> + rc = smb2_set_info_file(work, fp, req, work->tcon->share_conf); >>> break; >>> case SMB2_O_INFO_SECURITY: >>> ksmbd_debug(SMB, "GOT SMB2_O_INFO_SECURITY\n"); >>> diff --git a/fs/ksmbd/smb2pdu.h b/fs/ksmbd/smb2pdu.h >>> index bcec845b03f3..261825d06391 100644 >>> --- a/fs/ksmbd/smb2pdu.h >>> +++ b/fs/ksmbd/smb2pdu.h >>> @@ -1464,6 +1464,15 @@ struct smb2_file_all_info { /* data block >>> encoding >>> of response to level 18 */ >>> char FileName[1]; >>> } __packed; /* level 18 Query */ >>> >>> +struct smb2_file_basic_info { /* data block encoding of response to >>> level >>> 18 */ >>> + __le64 CreationTime; /* Beginning of FILE_BASIC_INFO equivalent */ >>> + __le64 LastAccessTime; >>> + __le64 LastWriteTime; >>> + __le64 ChangeTime; >>> + __le32 Attributes; >>> + __u32 Pad1; /* End of FILE_BASIC_INFO_INFO equivalent */ >>> +} __packed; >>> + >>> struct smb2_file_alt_name_info { >>> __le32 FileNameLength; >>> char FileName[0]; >>> >> >