From: Shyam Prasad N <sprasad@microsoft.com>
Date: Thu, 18 Feb 2021 13:03:23 +0000
Subject: [PATCH] cifs: Change SIDs in ACEs while transferring file ownership.
Git-commit: bc3e9dd9d104ca1b75644eab87b38ce8a924aef4
References: bsc#1190317
Patch-mainline: v5.12-rc1
With cifsacl, when a file/dir ownership is transferred (chown/chgrp),
the ACEs in the DACL for that file will need to replace the old owner
SIDs with the new owner SID.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Enzo Matsumiya <ematsumiya@suse.de>
---
fs/cifs/cifsacl.c | 139 ++++++++++++++++++++++++++++++----------------
1 file changed, 92 insertions(+), 47 deletions(-)
diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index 5d71fe1088bc..d44bfa62c1cd 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -525,8 +525,11 @@ exit_cifs_idmap(void)
}
/* copy ntsd, owner sid, and group sid from a security descriptor to another */
-static void copy_sec_desc(const struct cifs_ntsd *pntsd,
- struct cifs_ntsd *pnntsd, __u32 sidsoffset)
+static __u32 copy_sec_desc(const struct cifs_ntsd *pntsd,
+ struct cifs_ntsd *pnntsd,
+ __u32 sidsoffset,
+ struct cifs_sid *pownersid,
+ struct cifs_sid *pgrpsid)
{
struct cifs_sid *owner_sid_ptr, *group_sid_ptr;
struct cifs_sid *nowner_sid_ptr, *ngroup_sid_ptr;
@@ -540,19 +543,25 @@ static void copy_sec_desc(const struct cifs_ntsd *pntsd,
pnntsd->gsidoffset = cpu_to_le32(sidsoffset + sizeof(struct cifs_sid));
/* copy owner sid */
- owner_sid_ptr = (struct cifs_sid *)((char *)pntsd +
+ if (pownersid)
+ owner_sid_ptr = pownersid;
+ else
+ owner_sid_ptr = (struct cifs_sid *)((char *)pntsd +
le32_to_cpu(pntsd->osidoffset));
nowner_sid_ptr = (struct cifs_sid *)((char *)pnntsd + sidsoffset);
cifs_copy_sid(nowner_sid_ptr, owner_sid_ptr);
/* copy group sid */
- group_sid_ptr = (struct cifs_sid *)((char *)pntsd +
+ if (pgrpsid)
+ group_sid_ptr = pgrpsid;
+ else
+ group_sid_ptr = (struct cifs_sid *)((char *)pntsd +
le32_to_cpu(pntsd->gsidoffset));
ngroup_sid_ptr = (struct cifs_sid *)((char *)pnntsd + sidsoffset +
sizeof(struct cifs_sid));
cifs_copy_sid(ngroup_sid_ptr, group_sid_ptr);
- return;
+ return sidsoffset + (2 * sizeof(struct cifs_sid));
}
@@ -667,15 +676,21 @@ static void mode_to_access_flags(umode_t mode, umode_t bits_to_use,
return;
}
-static __u16 cifs_copy_ace(struct cifs_ace *dst, struct cifs_ace *src)
+static __u16 cifs_copy_ace(struct cifs_ace *dst, struct cifs_ace *src, struct cifs_sid *psid)
{
__u16 size = 1 + 1 + 2 + 4;
dst->type = src->type;
dst->flags = src->flags;
- dst->size = src->size;
dst->access_req = src->access_req;
- size += cifs_copy_sid(&dst->sid, &src->sid);
+
+ /* Check if there's a replacement sid specified */
+ if (psid)
+ size += cifs_copy_sid(&dst->sid, psid);
+ else
+ size += cifs_copy_sid(&dst->sid, &src->sid);
+
+ dst->size = cpu_to_le16(size);
return size;
}
@@ -1053,11 +1068,11 @@ static __u16 replace_sids_and_copy_aces(struct cifs_acl *pdacl, struct cifs_acl
pnntace = (struct cifs_ace *) (nacl_base + nsize);
if (pnownersid && compare_sids(&pntace->sid, pownersid) == 0)
- ace_size = cifs_copy_ace(pnntace, pntace);
+ ace_size = cifs_copy_ace(pnntace, pntace, pnownersid);
else if (pngrpsid && compare_sids(&pntace->sid, pgrpsid) == 0)
- ace_size = cifs_copy_ace(pnntace, pntace);
+ ace_size = cifs_copy_ace(pnntace, pntace, pngrpsid);
else
- ace_size = cifs_copy_ace(pnntace, pntace);
+ ace_size = cifs_copy_ace(pnntace, pntace, NULL);
size += le16_to_cpu(pntace->size);
nsize += ace_size;
@@ -1124,7 +1139,7 @@ static int set_chmod_dacl(struct cifs_acl *pdacl, struct cifs_acl *pndacl,
goto next_ace;
}
- nsize += cifs_copy_ace(pnntace, pntace);
+ nsize += cifs_copy_ace(pnntace, pntace, NULL);
num_aces++;
next_ace:
@@ -1250,25 +1265,27 @@ static int build_sec_desc(struct cifs_ntsd *pntsd, struct cifs_ntsd *pnntsd,
__u32 ndacloffset;
__u32 sidsoffset;
struct cifs_sid *owner_sid_ptr, *group_sid_ptr;
- struct cifs_sid *nowner_sid_ptr, *ngroup_sid_ptr;
+ struct cifs_sid *nowner_sid_ptr = NULL, *ngroup_sid_ptr = NULL;
struct cifs_acl *dacl_ptr = NULL; /* no need for SACL ptr */
struct cifs_acl *ndacl_ptr = NULL; /* no need for SACL ptr */
char *end_of_acl = ((char *)pntsd) + secdesclen;
+ u16 size = 0;
- if (pnmode && *pnmode != NO_CHANGE_64) { /* chmod */
- owner_sid_ptr = (struct cifs_sid *)((char *)pntsd +
- le32_to_cpu(pntsd->osidoffset));
- group_sid_ptr = (struct cifs_sid *)((char *)pntsd +
- le32_to_cpu(pntsd->gsidoffset));
- dacloffset = le32_to_cpu(pntsd->dacloffset);
- if (dacloffset) {
- dacl_ptr = (struct cifs_acl *)((char *)pntsd + dacloffset);
- if (end_of_acl < (char *)dacl_ptr + le16_to_cpu(dacl_ptr->size)) {
- cifs_dbg(VFS, "Existing ACL size is wrong. Discarding old ACL\n");
- dacl_ptr = NULL;
- }
+ dacloffset = le32_to_cpu(pntsd->dacloffset);
+ if (dacloffset) {
+ dacl_ptr = (struct cifs_acl *)((char *)pntsd + dacloffset);
+ if (end_of_acl < (char *)dacl_ptr + le16_to_cpu(dacl_ptr->size)) {
+ cifs_dbg(VFS, "Existing ACL size is wrong. Discarding old ACL\n");
+ dacl_ptr = NULL;
}
+ }
+
+ owner_sid_ptr = (struct cifs_sid *)((char *)pntsd +
+ le32_to_cpu(pntsd->osidoffset));
+ group_sid_ptr = (struct cifs_sid *)((char *)pntsd +
+ le32_to_cpu(pntsd->gsidoffset));
+ if (pnmode && *pnmode != NO_CHANGE_64) { /* chmod */
ndacloffset = sizeof(struct cifs_ntsd);
ndacl_ptr = (struct cifs_acl *)((char *)pnntsd + ndacloffset);
ndacl_ptr->revision =
@@ -1279,11 +1296,13 @@ static int build_sec_desc(struct cifs_ntsd *pntsd, struct cifs_ntsd *pnntsd,
rc = set_chmod_dacl(dacl_ptr, ndacl_ptr, owner_sid_ptr, group_sid_ptr,
pnmode, mode_from_sid);
+
sidsoffset = ndacloffset + le16_to_cpu(ndacl_ptr->size);
- /* copy sec desc control portion & owner and group sids */
- copy_sec_desc(pntsd, pnntsd, sidsoffset);
- *pnsecdesclen = sidsoffset + (2 * sizeof(struct cifs_sid));
- *aclflag = CIFS_ACL_DACL;
+ /* copy the non-dacl portion of secdesc */
+ *pnsecdesclen = copy_sec_desc(pntsd, pnntsd, sidsoffset,
+ NULL, NULL);
+
+ *aclflag |= CIFS_ACL_DACL;
} else {
ndacloffset = sizeof(struct cifs_ntsd);
ndacl_ptr = (struct cifs_acl *)((char *)pnntsd + ndacloffset);
@@ -1293,12 +1312,12 @@ static int build_sec_desc(struct cifs_ntsd *pntsd, struct cifs_ntsd *pnntsd,
if (uid_valid(uid)) { /* chown */
uid_t id;
- owner_sid_ptr = (struct cifs_sid *)((char *)pnntsd +
- le32_to_cpu(pnntsd->osidoffset));
nowner_sid_ptr = kmalloc(sizeof(struct cifs_sid),
GFP_KERNEL);
- if (!nowner_sid_ptr)
- return -ENOMEM;
+ if (!nowner_sid_ptr) {
+ rc = -ENOMEM;
+ goto chown_chgrp_exit;
+ }
id = from_kuid(&init_user_ns, uid);
if (id_from_sid) {
struct owner_sid *osid = (struct owner_sid *)nowner_sid_ptr;
@@ -1309,27 +1328,25 @@ static int build_sec_desc(struct cifs_ntsd *pntsd, struct cifs_ntsd *pnntsd,
osid->SubAuthorities[0] = cpu_to_le32(88);
osid->SubAuthorities[1] = cpu_to_le32(1);
osid->SubAuthorities[2] = cpu_to_le32(id);
+
} else { /* lookup sid with upcall */
rc = id_to_sid(id, SIDOWNER, nowner_sid_ptr);
if (rc) {
cifs_dbg(FYI, "%s: Mapping error %d for owner id %d\n",
__func__, rc, id);
- kfree(nowner_sid_ptr);
- return rc;
+ goto chown_chgrp_exit;
}
}
- cifs_copy_sid(owner_sid_ptr, nowner_sid_ptr);
- kfree(nowner_sid_ptr);
- *aclflag = CIFS_ACL_OWNER;
+ *aclflag |= CIFS_ACL_OWNER;
}
if (gid_valid(gid)) { /* chgrp */
gid_t id;
- group_sid_ptr = (struct cifs_sid *)((char *)pnntsd +
- le32_to_cpu(pnntsd->gsidoffset));
ngroup_sid_ptr = kmalloc(sizeof(struct cifs_sid),
GFP_KERNEL);
- if (!ngroup_sid_ptr)
- return -ENOMEM;
+ if (!ngroup_sid_ptr) {
+ rc = -ENOMEM;
+ goto chown_chgrp_exit;
+ }
id = from_kgid(&init_user_ns, gid);
if (id_from_sid) {
struct owner_sid *gsid = (struct owner_sid *)ngroup_sid_ptr;
@@ -1340,19 +1357,35 @@ static int build_sec_desc(struct cifs_ntsd *pntsd, struct cifs_ntsd *pnntsd,
gsid->SubAuthorities[0] = cpu_to_le32(88);
gsid->SubAuthorities[1] = cpu_to_le32(2);
gsid->SubAuthorities[2] = cpu_to_le32(id);
+
} else { /* lookup sid with upcall */
rc = id_to_sid(id, SIDGROUP, ngroup_sid_ptr);
if (rc) {
cifs_dbg(FYI, "%s: Mapping error %d for group id %d\n",
__func__, rc, id);
- kfree(ngroup_sid_ptr);
- return rc;
+ goto chown_chgrp_exit;
}
}
- cifs_copy_sid(group_sid_ptr, ngroup_sid_ptr);
- kfree(ngroup_sid_ptr);
- *aclflag = CIFS_ACL_GROUP;
+ *aclflag |= CIFS_ACL_GROUP;
}
+
+ if (dacloffset) {
+ /* Replace ACEs for old owner with new one */
+ size = replace_sids_and_copy_aces(dacl_ptr, ndacl_ptr,
+ owner_sid_ptr, group_sid_ptr,
+ nowner_sid_ptr, ngroup_sid_ptr);
+ ndacl_ptr->size = cpu_to_le16(size);
+ }
+
+ sidsoffset = ndacloffset + le16_to_cpu(ndacl_ptr->size);
+ /* copy the non-dacl portion of secdesc */
+ *pnsecdesclen = copy_sec_desc(pntsd, pnntsd, sidsoffset,
+ nowner_sid_ptr, ngroup_sid_ptr);
+
+chown_chgrp_exit:
+ /* errors could jump here. So make sure we return soon after this */
+ kfree(nowner_sid_ptr);
+ kfree(ngroup_sid_ptr);
}
return rc;
@@ -1598,6 +1631,18 @@ id_mode_to_cifs_acl(struct inode *inode, const char *path, __u64 *pnmode,
nsecdesclen += sizeof(struct cifs_ace);
else /* cifsacl */
nsecdesclen += 5 * sizeof(struct cifs_ace);
+ } else { /* chown */
+ /* When ownership changes, changes new owner sid length could be different */
+ nsecdesclen = sizeof(struct cifs_ntsd) + (sizeof(struct cifs_sid) * 2);
+ dacloffset = le32_to_cpu(pntsd->dacloffset);
+ if (dacloffset) {
+ dacl_ptr = (struct cifs_acl *)((char *)pntsd + dacloffset);
+ if (mode_from_sid)
+ nsecdesclen +=
+ le16_to_cpu(dacl_ptr->num_aces) * sizeof(struct cifs_ace);
+ else /* cifsacl */
+ nsecdesclen += le16_to_cpu(dacl_ptr->size);
+ }
}
/*
--
2.33.0