inode: make init and permission helpers idmapped mount aware

The inode_owner_or_capable() helper determines whether the caller is the
owner of the inode or is capable with respect to that inode. Allow it to
handle idmapped mounts. If the inode is accessed through an idmapped
mount it according to the mount's user namespace. Afterwards the checks
are identical to non-idmapped mounts. If the initial user namespace is
passed nothing changes so non-idmapped mounts will see identical
behavior as before.

Similarly, allow the inode_init_owner() helper to handle idmapped
mounts. It initializes a new inode on idmapped mounts by mapping the
fsuid and fsgid of the caller from the mount's user namespace. If the
initial user namespace is passed nothing changes so non-idmapped mounts
will see identical behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-7-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
This commit is contained in:
Christian Brauner
2021-01-21 14:19:25 +01:00
parent 47291baa8d
commit 21cb47be6f
54 changed files with 112 additions and 91 deletions

View File

@@ -213,7 +213,7 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
const char *comp = NULL;
u32 binode_flags;
if (!inode_owner_or_capable(inode))
if (!inode_owner_or_capable(&init_user_ns, inode))
return -EPERM;
if (btrfs_root_readonly(root))
@@ -429,7 +429,7 @@ static int btrfs_ioctl_fssetxattr(struct file *file, void __user *arg)
unsigned old_i_flags;
int ret = 0;
if (!inode_owner_or_capable(inode))
if (!inode_owner_or_capable(&init_user_ns, inode))
return -EPERM;
if (btrfs_root_readonly(root))
@@ -1862,7 +1862,7 @@ static noinline int __btrfs_ioctl_snap_create(struct file *file,
btrfs_info(BTRFS_I(file_inode(file))->root->fs_info,
"Snapshot src from another FS");
ret = -EXDEV;
} else if (!inode_owner_or_capable(src_inode)) {
} else if (!inode_owner_or_capable(&init_user_ns, src_inode)) {
/*
* Subvolume creation is not restricted, but snapshots
* are limited to own subvolumes only
@@ -1982,7 +1982,7 @@ static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
u64 flags;
int ret = 0;
if (!inode_owner_or_capable(inode))
if (!inode_owner_or_capable(&init_user_ns, inode))
return -EPERM;
ret = mnt_want_write_file(file);
@@ -4453,7 +4453,7 @@ static long _btrfs_ioctl_set_received_subvol(struct file *file,
int ret = 0;
int received_uuid_changed;
if (!inode_owner_or_capable(inode))
if (!inode_owner_or_capable(&init_user_ns, inode))
return -EPERM;
ret = mnt_want_write_file(file);