From af320a739029f6f8c5c05e769fadaf88e9b7d34f Mon Sep 17 00:00:00 2001 From: Namjae Jeon Date: Wed, 21 Jul 2021 10:03:19 +0900 Subject: ksmbd: add negotiate context verification This patch add negotiate context verification code to check bounds. Signed-off-by: Namjae Jeon Signed-off-by: Steve French --- fs/ksmbd/smb2pdu.c | 118 ++++++++++++++++++++++++++++------------------------- fs/ksmbd/smb2pdu.h | 6 +-- 2 files changed, 65 insertions(+), 59 deletions(-) (limited to 'fs') diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c index 77e42a572825..64a4d66997a3 100644 --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -835,10 +835,10 @@ static void assemble_neg_contexts(struct ksmbd_conn *conn, build_encrypt_ctxt((struct smb2_encryption_neg_context *)pneg_ctxt, conn->cipher_type); rsp->NegotiateContextCount = cpu_to_le16(++neg_ctxt_cnt); - ctxt_size += sizeof(struct smb2_encryption_neg_context); + ctxt_size += sizeof(struct smb2_encryption_neg_context) + 2; /* Round to 8 byte boundary */ pneg_ctxt += - round_up(sizeof(struct smb2_encryption_neg_context), + round_up(sizeof(struct smb2_encryption_neg_context) + 2, 8); } @@ -850,9 +850,10 @@ static void assemble_neg_contexts(struct ksmbd_conn *conn, build_compression_ctxt((struct smb2_compression_ctx *)pneg_ctxt, conn->compress_algorithm); rsp->NegotiateContextCount = cpu_to_le16(++neg_ctxt_cnt); - ctxt_size += sizeof(struct smb2_compression_ctx); + ctxt_size += sizeof(struct smb2_compression_ctx) + 2; /* Round to 8 byte boundary */ - pneg_ctxt += round_up(sizeof(struct smb2_compression_ctx), 8); + pneg_ctxt += round_up(sizeof(struct smb2_compression_ctx) + 2, + 8); } if (conn->posix_ext_supported) { @@ -881,16 +882,23 @@ static __le32 decode_preauth_ctxt(struct ksmbd_conn *conn, return err; } -static int decode_encrypt_ctxt(struct ksmbd_conn *conn, - struct smb2_encryption_neg_context *pneg_ctxt) +static void decode_encrypt_ctxt(struct ksmbd_conn *conn, + struct smb2_encryption_neg_context *pneg_ctxt, + int len_of_ctxts) { - int i; int cph_cnt = le16_to_cpu(pneg_ctxt->CipherCount); + int i, cphs_size = cph_cnt * sizeof(__le16); conn->cipher_type = 0; + if (sizeof(struct smb2_encryption_neg_context) + cphs_size > + len_of_ctxts) { + pr_err("Invalid cipher count(%d)\n", cph_cnt); + return; + } + if (!(server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION)) - goto out; + return; for (i = 0; i < cph_cnt; i++) { if (pneg_ctxt->Ciphers[i] == SMB2_ENCRYPTION_AES128_GCM || @@ -903,90 +911,88 @@ static int decode_encrypt_ctxt(struct ksmbd_conn *conn, break; } } - -out: - /* - * Return encrypt context size in request. - * So need to plus extra number of ciphers size. - */ - return sizeof(struct smb2_encryption_neg_context) + - ((cph_cnt - 1) * 2); } -static int decode_compress_ctxt(struct ksmbd_conn *conn, - struct smb2_compression_ctx *pneg_ctxt) +static void decode_compress_ctxt(struct ksmbd_conn *conn, + struct smb2_compression_ctx *pneg_ctxt) { - int algo_cnt = le16_to_cpu(pneg_ctxt->CompressionAlgorithmCount); - conn->compress_algorithm = SMB3_COMPRESS_NONE; - - /* - * Return compression context size in request. - * So need to plus extra number of CompressionAlgorithms size. - */ - return sizeof(struct smb2_compression_ctx) + - ((algo_cnt - 1) * 2); } static __le32 deassemble_neg_contexts(struct ksmbd_conn *conn, struct smb2_negotiate_req *req) { - int i = 0; - __le32 status = 0; /* +4 is to account for the RFC1001 len field */ - char *pneg_ctxt = (char *)req + - le32_to_cpu(req->NegotiateContextOffset) + 4; - __le16 *ContextType = (__le16 *)pneg_ctxt; + struct smb2_neg_context *pctx = (struct smb2_neg_context *)((char *)req + 4); + int i = 0, len_of_ctxts; + int offset = le32_to_cpu(req->NegotiateContextOffset); int neg_ctxt_cnt = le16_to_cpu(req->NegotiateContextCount); - int ctxt_size; + int len_of_smb = be32_to_cpu(req->hdr.smb2_buf_length); + __le32 status = STATUS_INVALID_PARAMETER; + + ksmbd_debug(SMB, "decoding %d negotiate contexts\n", neg_ctxt_cnt); + if (len_of_smb <= offset) { + ksmbd_debug(SMB, "Invalid response: negotiate context offset\n"); + return status; + } + + len_of_ctxts = len_of_smb - offset; - ksmbd_debug(SMB, "negotiate context count = %d\n", neg_ctxt_cnt); - status = STATUS_INVALID_PARAMETER; while (i++ < neg_ctxt_cnt) { - if (*ContextType == SMB2_PREAUTH_INTEGRITY_CAPABILITIES) { + int clen; + + /* check that offset is not beyond end of SMB */ + if (len_of_ctxts == 0) + break; + + if (len_of_ctxts < sizeof(struct smb2_neg_context)) + break; + + pctx = (struct smb2_neg_context *)((char *)pctx + offset); + clen = le16_to_cpu(pctx->DataLength); + if (clen + sizeof(struct smb2_neg_context) > len_of_ctxts) + break; + + if (pctx->ContextType == SMB2_PREAUTH_INTEGRITY_CAPABILITIES) { ksmbd_debug(SMB, "deassemble SMB2_PREAUTH_INTEGRITY_CAPABILITIES context\n"); if (conn->preauth_info->Preauth_HashId) break; status = decode_preauth_ctxt(conn, - (struct smb2_preauth_neg_context *)pneg_ctxt); - pneg_ctxt += DIV_ROUND_UP(sizeof(struct smb2_preauth_neg_context), 8) * 8; - } else if (*ContextType == SMB2_ENCRYPTION_CAPABILITIES) { + (struct smb2_preauth_neg_context *)pctx); + if (status != STATUS_SUCCESS) + break; + } else if (pctx->ContextType == SMB2_ENCRYPTION_CAPABILITIES) { ksmbd_debug(SMB, "deassemble SMB2_ENCRYPTION_CAPABILITIES context\n"); if (conn->cipher_type) break; - ctxt_size = decode_encrypt_ctxt(conn, - (struct smb2_encryption_neg_context *)pneg_ctxt); - pneg_ctxt += DIV_ROUND_UP(ctxt_size, 8) * 8; - } else if (*ContextType == SMB2_COMPRESSION_CAPABILITIES) { + decode_encrypt_ctxt(conn, + (struct smb2_encryption_neg_context *)pctx, + len_of_ctxts); + } else if (pctx->ContextType == SMB2_COMPRESSION_CAPABILITIES) { ksmbd_debug(SMB, "deassemble SMB2_COMPRESSION_CAPABILITIES context\n"); if (conn->compress_algorithm) break; - ctxt_size = decode_compress_ctxt(conn, - (struct smb2_compression_ctx *)pneg_ctxt); - pneg_ctxt += DIV_ROUND_UP(ctxt_size, 8) * 8; - } else if (*ContextType == SMB2_NETNAME_NEGOTIATE_CONTEXT_ID) { + decode_compress_ctxt(conn, + (struct smb2_compression_ctx *)pctx); + } else if (pctx->ContextType == SMB2_NETNAME_NEGOTIATE_CONTEXT_ID) { ksmbd_debug(SMB, "deassemble SMB2_NETNAME_NEGOTIATE_CONTEXT_ID context\n"); - ctxt_size = sizeof(struct smb2_netname_neg_context); - ctxt_size += DIV_ROUND_UP(le16_to_cpu(((struct smb2_netname_neg_context *) - pneg_ctxt)->DataLength), 8) * 8; - pneg_ctxt += ctxt_size; - } else if (*ContextType == SMB2_POSIX_EXTENSIONS_AVAILABLE) { + } else if (pctx->ContextType == SMB2_POSIX_EXTENSIONS_AVAILABLE) { ksmbd_debug(SMB, "deassemble SMB2_POSIX_EXTENSIONS_AVAILABLE context\n"); conn->posix_ext_supported = true; - pneg_ctxt += DIV_ROUND_UP(sizeof(struct smb2_posix_neg_context), 8) * 8; } - ContextType = (__le16 *)pneg_ctxt; - if (status != STATUS_SUCCESS) - break; + /* offsets must be 8 byte aligned */ + clen = (clen + 7) & ~0x7; + offset = clen + sizeof(struct smb2_neg_context); + len_of_ctxts -= clen + sizeof(struct smb2_neg_context); } return status; } diff --git a/fs/ksmbd/smb2pdu.h b/fs/ksmbd/smb2pdu.h index 0eac40e1ba65..21cb93e771f7 100644 --- a/fs/ksmbd/smb2pdu.h +++ b/fs/ksmbd/smb2pdu.h @@ -299,7 +299,7 @@ struct smb2_encryption_neg_context { __le32 Reserved; /* CipherCount usally 2, but can be 3 when AES256-GCM enabled */ __le16 CipherCount; /* AES-128-GCM and AES-128-CCM by default */ - __le16 Ciphers[1]; + __le16 Ciphers[]; } __packed; #define SMB3_COMPRESS_NONE cpu_to_le16(0x0000) @@ -314,7 +314,7 @@ struct smb2_compression_ctx { __le16 CompressionAlgorithmCount; __u16 Padding; __le32 Reserved1; - __le16 CompressionAlgorithms[1]; + __le16 CompressionAlgorithms[]; } __packed; #define POSIX_CTXT_DATA_LEN 16 @@ -329,7 +329,7 @@ struct smb2_netname_neg_context { __le16 ContextType; /* 0x100 */ __le16 DataLength; __le32 Reserved; - __le16 NetName[0]; /* hostname of target converted to UCS-2 */ + __le16 NetName[]; /* hostname of target converted to UCS-2 */ } __packed; struct smb2_negotiate_rsp { -- cgit v1.2.3-58-ga151