From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 114D44D4881 for ; Thu, 17 Sep 2026 18:39:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789670386; cv=none; b=iJUV228XIrtwg9S0XCoGLLkm9g5kfDVlaPQd43uV/Bgy5N/ix2L2KsVMcOVRXhB4U6FBkKp+kglwAXw+yTUN4ipfJi+ttMdh7ePlS3fZexLlZJfUW0o4MDjAWWj/3HML4vBLD2buvXK9s18UiMAFnI+pVcaSTlZ4vNeTgYbx0h8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789670386; c=relaxed/simple; bh=dL8H538mFx2CSdrFCk6twLHVyVI/MT57XPbWIeCgidg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aKYkgk6ap76OH8yWnWBzavmMZ6sF9cQKzNsw9YzmargGmzvUCupVF9VE9QKCAlODwom4lbjZi2ZKXLu/0rvTFp3FVRUQ82hyqHar0ogBlrit74bcLpU39ZMW7WDGEfurnXmtRf34kJtPuKXTxOmdGj/B7kxt9wN442fQ3nxMZG0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZvXZ/9Xl; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZvXZ/9Xl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8CAD1F00898; Thu, 17 Sep 2026 18:39:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789670384; bh=EtZD8MSc6FzCihdWTITPYmDr64WgeE3MEgP97paQznQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ZvXZ/9XlX9hSGEUajrSzXwYoy4BXUvqAY35It3RNt9ICvRTSGbLD6yBLt0REZcMnq UbtN0o3ow1oK1kSl2fK7Q6raFrHRJo1whZzY6U6Wn487IynieqkD7vloowlidWXcK9 ki4gdXzS38/qKkIyk6MO7cu4T8KwZSo9fJWhVRnseCvAcpjTQ2l2VoUAwbJa/+870R E60lyPHAk4VKMnhhn42n6xX1tPJ04FE7g0WpC0mHcpXd5gTF5qmGtYoURv7ti4lzM4 ZhUt6l7ZkHs63voFryW8oMPWsbdDkJTfpzgFntCyeyccm5IADD8UcWAqUVoJg5nCIQ wJaCgGTEwd/Qg== From: Sasha Levin To: stable@vger.kernel.org Cc: Paulo Alcantara , Namjae Jeon , Ronnie Sahlberg , Shyam Prasad N , Tom Talpey , Bharath SM , Sasha Levin Subject: [PATCH 5.10.y] smb: client: honor forceuid/forcegid when mapping SIDs to uid/gid Date: Thu, 17 Sep 2026 14:39:42 -0400 Message-ID: <20260917183942.1201249-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026091607-spool-dagger-d4a5@gregkh> References: <2026091607-spool-dagger-d4a5@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Paulo Alcantara [ Upstream commit 18a72975e9f35aadecc75b031f693f2d1f49308f ] When the administrator mounts with forceuid or forcegid (uid=/gid= mount options), they expect all files to appear owned by the specified user/group. However, several code paths unconditionally called sid_to_id() to overwrite cf_uid/cf_gid with server-provided values, ignoring the administrator's explicit override: - smb311_posix_info_to_fattr() (stat via POSIX extensions) - cifs_posix_to_fattr() (readdir via POSIX extensions) - parse_sec_desc() (CIFS ACL ownership mapping) This allowed an untrusted server to dictate local file ownership even when the mount was configured to force specific uid/gid values. Fix all three call sites to check CIFS_MOUNT_OVERR_UID and CIFS_MOUNT_OVERR_GID before calling sid_to_id(), following the same pattern already used by cifs_unix_basic_to_fattr() for unix extensions. Closes: https://sashiko.dev/#/patchset/20260906155816.603278-1-pc%40manguebit.org Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara Cc: Ronnie Sahlberg Cc: Shyam Prasad N Cc: Tom Talpey Cc: Bharath SM Cc: stable@vger.kernel.org [ adapted the patch to fs/cifs/ using legacy mount fields and parse_sid(). ] Signed-off-by: Sasha Levin --- fs/cifs/cifsacl.c | 29 ++++++++++++++++++----------- fs/cifs/readdir.c | 9 +++++++-- 2 files changed, 25 insertions(+), 13 deletions(-) diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c index c8a0a2edc6500..486bccf548c35 100644 --- a/fs/cifs/cifsacl.c +++ b/fs/cifs/cifsacl.c @@ -947,6 +947,7 @@ static int parse_sec_desc(struct cifs_sb_info *cifs_sb, { int rc = 0; struct cifs_sid *owner_sid_ptr, *group_sid_ptr; + unsigned int sbflags = cifs_sb->mnt_cifs_flags; struct cifs_acl *dacl_ptr; /* no need for SACL ptr */ char *end_of_acl = ((char *)pntsd) + acl_len; __u32 dacloffset; @@ -964,17 +965,21 @@ static int parse_sec_desc(struct cifs_sb_info *cifs_sb, pntsd->revision, pntsd->type, le32_to_cpu(pntsd->osidoffset), le32_to_cpu(pntsd->gsidoffset), le32_to_cpu(pntsd->sacloffset), dacloffset); -/* cifs_dump_mem("owner_sid: ", owner_sid_ptr, 64); */ + fattr->cf_uid = cifs_sb->mnt_uid; + fattr->cf_gid = cifs_sb->mnt_gid; + rc = parse_sid(owner_sid_ptr, end_of_acl); if (rc) { cifs_dbg(FYI, "%s: Error %d parsing Owner SID\n", __func__, rc); return rc; } - rc = sid_to_id(cifs_sb, owner_sid_ptr, fattr, SIDOWNER); - if (rc) { - cifs_dbg(FYI, "%s: Error %d mapping Owner SID to uid\n", - __func__, rc); - return rc; + if (!(sbflags & CIFS_MOUNT_OVERR_UID)) { + rc = sid_to_id(cifs_sb, owner_sid_ptr, fattr, SIDOWNER); + if (rc) { + cifs_dbg(FYI, "%s: Error %d mapping Owner SID to uid\n", + __func__, rc); + return rc; + } } rc = parse_sid(group_sid_ptr, end_of_acl); @@ -983,11 +988,13 @@ static int parse_sec_desc(struct cifs_sb_info *cifs_sb, __func__, rc); return rc; } - rc = sid_to_id(cifs_sb, group_sid_ptr, fattr, SIDGROUP); - if (rc) { - cifs_dbg(FYI, "%s: Error %d mapping Group SID to gid\n", - __func__, rc); - return rc; + if (!(sbflags & CIFS_MOUNT_OVERR_GID)) { + rc = sid_to_id(cifs_sb, group_sid_ptr, fattr, SIDGROUP); + if (rc) { + cifs_dbg(FYI, "%s: Error %d mapping Group SID to gid\n", + __func__, rc); + return rc; + } } if (dacloffset) diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c index 9a7315aa24e0d..2e130228f2183 100644 --- a/fs/cifs/readdir.c +++ b/fs/cifs/readdir.c @@ -246,6 +246,7 @@ static void cifs_posix_to_fattr(struct cifs_fattr *fattr, struct smb2_posix_info *info, struct cifs_sb_info *cifs_sb) { + unsigned int sbflags = cifs_sb->mnt_cifs_flags; struct smb2_posix_info_parsed parsed; posix_info_parse(info, NULL, &parsed); @@ -290,8 +291,12 @@ cifs_posix_to_fattr(struct cifs_fattr *fattr, struct smb2_posix_info *info, if (reparse_file_needs_reval(fattr)) fattr->cf_flags |= CIFS_FATTR_NEED_REVAL; - sid_to_id(cifs_sb, &parsed.owner, fattr, SIDOWNER); - sid_to_id(cifs_sb, &parsed.group, fattr, SIDGROUP); + fattr->cf_uid = cifs_sb->mnt_uid; + fattr->cf_gid = cifs_sb->mnt_gid; + if (!(sbflags & CIFS_MOUNT_OVERR_UID)) + sid_to_id(cifs_sb, &parsed.owner, fattr, SIDOWNER); + if (!(sbflags & CIFS_MOUNT_OVERR_GID)) + sid_to_id(cifs_sb, &parsed.group, fattr, SIDGROUP); } static void __dir_info_to_fattr(struct cifs_fattr *fattr, const void *info) -- 2.53.0