From: Sargun Dhillon
mainline inclusion
from mainline-5.11-rc1
commit d18a9d3fa0f27a47706fb67f1ee0f4d971587c4e
category: bugfix
issue: #I3ZXZF
CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
---------------------------
There was refactoring done to use the fs_context for mounting done in:
62a55d088cd87: NFS: Additional refactoring for fs_context conversion
This made it so that the net_ns is fetched from the fs_context (the netns
that fsopen is called in). This change also makes it so that the credential
fetched during fsopen is used as well as the net_ns.
NFS has already had a number of changes to prepare it for user namespaces:
1a58e8a0e5c1: NFS: Store the credential of the mount process in the nfs_server
264d948ce7d0: NFS: Convert NFSv3 to use the container user namespace
c207db2f5da5: NFS: Convert NFSv2 to use the container user namespace
Previously, different credentials could be used for creation of the
fs_context versus creation of the nfs_server, as FSCONFIG_CMD_CREATE did
the actual credential check, and that's where current_creds() were fetched.
This meant that the user namespace which fsopen was called in could be a
non-init user namespace. This still requires that the user that calls
FSCONFIG_CMD_CREATE has CAP_SYS_ADMIN in the init user ns.
This roughly allows a privileged user to mount on behalf of an unprivileged
usernamespace, by forking off and calling fsopen in the unprivileged user
namespace. It can then pass back that fsfd to the privileged process which
can configure the NFS mount, and then it can call FSCONFIG_CMD_CREATE
before switching back into the mount namespace of the container, and finish
up the mounting process and call fsmount and move_mount.
Signed-off-by: Sargun Dhillon
Tested-by: Alban Crequy
Fixes: 62a55d088cd8 ("NFS: Additional refactoring for fs_context conversion")
Signed-off-by: Trond Myklebust
Signed-off-by: Zhang Yi
Reviewed-by: Zhang Xiaoxu
Signed-off-by: Chen Jun
Signed-off-by: Yu Changchun
---
fs/nfs/client.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 723d425796cc..e365ef543f4e 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -571,7 +571,7 @@ static int nfs_start_lockd(struct nfs_server *server)
1 : 0,
.net = clp->cl_net,
.nlmclnt_ops = clp->cl_nfs_mod->rpc_ops->nlmclnt_ops,
- .cred = current_cred(),
+ .cred = server->cred,
};
if (nlm_init.nfs_version > 3)
@@ -985,7 +985,7 @@ struct nfs_server *nfs_create_server(struct fs_context *fc)
if (!server)
return ERR_PTR(-ENOMEM);
- server->cred = get_cred(current_cred());
+ server->cred = get_cred(fc->cred);
error = -ENOMEM;
fattr = nfs_alloc_fattr();
--
2.22.0
