FAILED: patch "[PATCH] smb: client: honor forceuid/forcegid when mapping SIDs to" failed to apply to 5.10-stable tree

PATCH New [email protected] 2 participants 2 messages Sep 16 – Sep 17

Subsystems (2)

Stable branch SMB client (CIFS)

lore

Share & tools

lore

[email protected]

author maintainer

2026-09-16 16:47 UTC #0 lore raw

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 18a72975e9f35aadecc75b031f693f2d1f49308f
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026091607-spool-dagger-d4a5@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 18a72975e9f35aadecc75b031f693f2d1f49308f Mon Sep 17 00:00:00 2001
From: Paulo Alcantara <[email protected]>
Date: Sun, 6 Sep 2026 14:40:04 -0300
Subject: [PATCH] smb: client: honor forceuid/forcegid when mapping SIDs to
uid/gid

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 <[email protected]>

Signed-off-by Paulo Alcantara <[email protected]>

Cc Ronnie Sahlberg <[email protected]>

Cc Shyam Prasad N <[email protected]>

Cc Tom Talpey <[email protected]>

Cc Bharath SM <[email protected]>

Cc [email protected]

fs/smb/client/cifsacl.c +18 ~~-11~~

index 213a421bf8e9..def8908dd7e9 100644
@@ -1346,6 +1346,7 @@ static int parse_sec_desc(struct cifs_sb_info *cifs_sb,
 {
 	int rc = 0;
 	struct smb_sid *owner_sid_ptr, *group_sid_ptr;
+	unsigned int sbflags = cifs_sb_flags(cifs_sb);
 	struct smb_acl *dacl_ptr; /* no need for SACL ptr */
 	char *end_of_acl;
 	__u32 dacloffset, osidoffset, gsidoffset;

@@ -1364,17 +1365,21 @@ static int parse_sec_desc(struct cifs_sb_info *cifs_sb,
 	cifs_dbg(NOISY, "revision %d type 0x%x ooffset 0x%x goffset 0x%x sacloffset 0x%x dacloffset 0x%x\n",
 		 pntsd->revision, pntsd->type, osidoffset, gsidoffset,
 		 le32_to_cpu(pntsd->sacloffset), dacloffset);
-/*	cifs_dump_mem("owner_sid: ", owner_sid_ptr, 64); */
+	fattr->cf_uid = cifs_sb->ctx->linux_uid;
+	fattr->cf_gid = cifs_sb->ctx->linux_gid;
+
 	rc = sid_from_sd(pntsd, acl_len, osidoffset, &owner_sid_ptr);
 	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 = sid_from_sd(pntsd, acl_len, gsidoffset, &group_sid_ptr);

@@ -1383,11 +1388,13 @@ 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) {

fs/smb/client/inode.c +7 -2

index 49f9993ad567..1fe0ef0a95db 100644
@@ -851,6 +851,7 @@ static void smb311_posix_info_to_fattr(struct cifs_fattr *fattr,
 	struct smb311_posix_qinfo *info = &data->posix_fi;
 	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
 	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
+	unsigned int sbflags = cifs_sb_flags(cifs_sb);
 
 	memset(fattr, 0, sizeof(*fattr));

@@ -895,8 +896,12 @@ static void smb311_posix_info_to_fattr(struct cifs_fattr *fattr,
 		fattr->cf_symlink_target = data->symlink_target;
 		data->symlink_target = NULL;
 	}
-	sid_to_id(cifs_sb, &data->posix_owner, fattr, SIDOWNER);
-	sid_to_id(cifs_sb, &data->posix_group, fattr, SIDGROUP);
+	fattr->cf_uid = cifs_sb->ctx->linux_uid;
+	fattr->cf_gid = cifs_sb->ctx->linux_gid;
+	if (!(sbflags & CIFS_MOUNT_OVERR_UID))
+		sid_to_id(cifs_sb, &data->posix_owner, fattr, SIDOWNER);
+	if (!(sbflags & CIFS_MOUNT_OVERR_GID))
+		sid_to_id(cifs_sb, &data->posix_group, fattr, SIDGROUP);
 
 	cifs_dbg(FYI, "POSIX query info: mode 0x%x uniqueid 0x%llx nlink %d\n",
 		fattr->cf_mode, fattr->cf_uniqueid, fattr->cf_nlink);

fs/smb/client/readdir.c +7 -2

index 32a75afca8f5..1ea84f4ada39 100644
@@ -242,6 +242,7 @@ 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_flags(cifs_sb);
 	struct smb2_posix_info_parsed parsed;
 
 	posix_info_parse(info, NULL, &parsed);

@@ -281,8 +282,12 @@ cifs_posix_to_fattr(struct cifs_fattr *fattr, struct smb2_posix_info *info,
 		 le32_to_cpu(info->ReparseTag),
 		 le32_to_cpu(info->Mode));
 
-	sid_to_id(cifs_sb, &parsed.owner, fattr, SIDOWNER);
-	sid_to_id(cifs_sb, &parsed.group, fattr, SIDGROUP);
+	fattr->cf_uid = cifs_sb->ctx->linux_uid;
+	fattr->cf_gid = cifs_sb->ctx->linux_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)

Sasha Levin

maintainer

2026-09-17 18:39 UTC #1 lore raw

PATCH 1/1 smb: client: honor forceuid/forcegid when mapping SIDs to uid/gid

From: Paulo Alcantara <[email protected]>

[ Upstream commit 18a72975e9f35aadecc75b031f693f2d1f49308f ]

- 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.

Closes https://sashiko.dev/#/patchset/20260906155816.603278-1-pc%40manguebit.org

Reviewed-by Namjae Jeon <[email protected]>

Signed-off-by Paulo Alcantara <[email protected]>

Cc Ronnie Sahlberg <[email protected]>

Cc Shyam Prasad N <[email protected]>

Cc Tom Talpey <[email protected]>

Cc Bharath SM <[email protected]>

Cc [email protected]

[ adapted the patch to fs/cifs/ using legacy mount fields and parse_sid(). ]

Signed-off-by Sasha Levin <[email protected]>

---
 fs/cifs/cifsacl.c | 29 ++++++++++++++++++-----------
 fs/cifs/readdir.c |  9 +++++++--
 2 files changed, 25 insertions(+), 13 deletions(-)

fs/cifs/cifsacl.c +18 ~~-11~~

index c8a0a2edc6500..486bccf548c35 100644
@@ -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)

fs/cifs/readdir.c +7 -2

index 9a7315aa24e0d..2e130228f2183 100644
@@ -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)

Signature · 1 line

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