diff options
| -rw-r--r-- | Documentation/filesystems/idmappings.rst | 5 | ||||
| -rw-r--r-- | fs/namespace.c | 5 |
2 files changed, 8 insertions, 2 deletions
diff --git a/Documentation/filesystems/idmappings.rst b/Documentation/filesystems/idmappings.rst index 7a879ec3b6bf..c1db8748389c 100644 --- a/Documentation/filesystems/idmappings.rst +++ b/Documentation/filesystems/idmappings.rst @@ -369,6 +369,11 @@ kernel maps the caller's userspace id down into a kernel id according to the caller's idmapping and then maps that kernel id up according to the filesystem's idmapping. +Let's see some examples with caller/filesystem idmapping but without mount +idmappings. This will exhibit some problems we can hit. After that we will +revisit/reconsider these examples, this time using mount idmappings, to see how +they can solve the problems we observed before. + Example 1 ~~~~~~~~~ diff --git a/fs/namespace.c b/fs/namespace.c index afe2b64b14f1..41461f55c039 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -4026,8 +4026,9 @@ static int can_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt) static inline bool mnt_allow_writers(const struct mount_kattr *kattr, const struct mount *mnt) { - return !(kattr->attr_set & MNT_READONLY) || - (mnt->mnt.mnt_flags & MNT_READONLY); + return (!(kattr->attr_set & MNT_READONLY) || + (mnt->mnt.mnt_flags & MNT_READONLY)) && + !kattr->mnt_userns; } static int mount_setattr_prepare(struct mount_kattr *kattr, struct mount *mnt) |