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Subject[PATCH review 18/85] coda: Restrict coda messages to the initial user namespace
From: "Eric W. Biederman" <ebiederm@xmission.com>

Remove the slight chance that uids and gids in coda messages will be
interpreted in the wrong user namespace.

- Only allow processes in the initial user namespace to open the coda
character device to communicate with coda filesystems.
- Explicitly convert the uids in the coda header into the initial user
namespace.
- In coda_vattr_to_attr make kuids and kgids from the initial user
namespace uids and gids in struct coda_vattr that just came from
userspace.
- In coda_iattr_to_vattr convert kuids and kgids into uids and gids
in the intial user namespace and store them in struct coda_vattr for
sending to coda userspace programs.

Nothing needs to be changed with mounts as coda does not support
being mounted in anything other than the initial user namespace.

Cc: Jan Harkes <jaharkes@cs.cmu.edu>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/coda/coda_linux.c | 8 ++++----
fs/coda/psdev.c | 3 +++
fs/coda/upcall.c | 6 +++---
include/linux/coda_psdev.h | 2 +-
4 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/fs/coda/coda_linux.c b/fs/coda/coda_linux.c
index 854ace7..2849f41 100644
--- a/fs/coda/coda_linux.c
+++ b/fs/coda/coda_linux.c
@@ -100,9 +100,9 @@ void coda_vattr_to_iattr(struct inode *inode, struct coda_vattr *attr)
if (attr->va_mode != (u_short) -1)
inode->i_mode = attr->va_mode | inode_type;
if (attr->va_uid != -1)
- inode->i_uid = (uid_t) attr->va_uid;
+ inode->i_uid = make_kuid(&init_user_ns, (uid_t) attr->va_uid);
if (attr->va_gid != -1)
- inode->i_gid = (gid_t) attr->va_gid;
+ inode->i_gid = make_kgid(&init_user_ns, (gid_t) attr->va_gid);
if (attr->va_nlink != -1)
set_nlink(inode, attr->va_nlink);
if (attr->va_size != -1)
@@ -171,10 +171,10 @@ void coda_iattr_to_vattr(struct iattr *iattr, struct coda_vattr *vattr)
vattr->va_mode = iattr->ia_mode;
}
if ( valid & ATTR_UID ) {
- vattr->va_uid = (vuid_t) iattr->ia_uid;
+ vattr->va_uid = (vuid_t) from_kuid(&init_user_ns, iattr->ia_uid);
}
if ( valid & ATTR_GID ) {
- vattr->va_gid = (vgid_t) iattr->ia_gid;
+ vattr->va_gid = (vgid_t) from_kgid(&init_user_ns, iattr->ia_gid);
}
if ( valid & ATTR_SIZE ) {
vattr->va_size = iattr->ia_size;
diff --git a/fs/coda/psdev.c b/fs/coda/psdev.c
index dd60f90..ebc2bae 100644
--- a/fs/coda/psdev.c
+++ b/fs/coda/psdev.c
@@ -270,6 +270,9 @@ static int coda_psdev_open(struct inode * inode, struct file * file)
if (task_active_pid_ns(current) != &init_pid_ns)
return -EINVAL;

+ if (current_user_ns() != &init_user_ns)
+ return -EINVAL;
+
idx = iminor(inode);
if (idx < 0 || idx >= MAX_CODADEVS)
return -ENODEV;
diff --git a/fs/coda/upcall.c b/fs/coda/upcall.c
index 5c6d2cd..3a73197 100644
--- a/fs/coda/upcall.c
+++ b/fs/coda/upcall.c
@@ -52,7 +52,7 @@ static void *alloc_upcall(int opcode, int size)
inp->ih.opcode = opcode;
inp->ih.pid = task_pid_nr_ns(current, &init_pid_ns);
inp->ih.pgid = task_pgrp_nr_ns(current, &init_pid_ns);
- inp->ih.uid = current_fsuid();
+ inp->ih.uid = from_kuid(&init_user_ns, current_fsuid());

return (void*)inp;
}
@@ -157,7 +157,7 @@ int venus_lookup(struct super_block *sb, struct CodaFid *fid,
}

int venus_close(struct super_block *sb, struct CodaFid *fid, int flags,
- vuid_t uid)
+ kuid_t uid)
{
union inputArgs *inp;
union outputArgs *outp;
@@ -166,7 +166,7 @@ int venus_close(struct super_block *sb, struct CodaFid *fid, int flags,
insize = SIZE(release);
UPARG(CODA_CLOSE);

- inp->ih.uid = uid;
+ inp->ih.uid = from_kuid(&init_user_ns, uid);
inp->coda_close.VFid = *fid;
inp->coda_close.flags = flags;

diff --git a/include/linux/coda_psdev.h b/include/linux/coda_psdev.h
index 8031d6e..5b8721e 100644
--- a/include/linux/coda_psdev.h
+++ b/include/linux/coda_psdev.h
@@ -34,7 +34,7 @@ int venus_lookup(struct super_block *sb, struct CodaFid *fid,
const char *name, int length, int *type,
struct CodaFid *resfid);
int venus_close(struct super_block *sb, struct CodaFid *fid, int flags,
- vuid_t uid);
+ kuid_t uid);
int venus_open(struct super_block *sb, struct CodaFid *fid, int flags,
struct file **f);
int venus_mkdir(struct super_block *sb, struct CodaFid *dirfid,
--
1.7.5.4


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