[GIT PULL] user namespace enhancements for Linux 3.5-rc1

Eric W. Biederman
2012-05-22T18:49:03Z

Linus,

please pull user namespace enhancements for v3.5-rc1 from:

git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git for-linus

The tree is against v3.4-rc1 aka dd775ae2549217d3ae09363e3edb305d0fa19928
The topmost commit is 4b06a81f1daee668fbd6de85557bfb36dd36078f

This is a course correction for the user namespace, so that we can reach
an inexpensive, maintainable, and reasonably complete implementation.

Highlights.
- Config guards make it impossible to enable the user namespace and
code that has not been converted to be user namespace safe.

- Use of the new kuid_t type ensures the if you somehow get past the
config guards the kernel will encounter type errors if you enable user
namespaces and attempt to compile in code whose permission checks have
not been updated to be user namespace safe.

- All uids from child user namespaces are mapped into the initial user
namespace before they are processed. Removing the need to add an
additional check to see if the user namespace of the compared uids
remains the same.

- With the user namespaces compiled out the performance is as good or
better than it is today.

- For most operations absolutely nothing changes performance or
operationally with the user namespace enabled.

- The worse case performance I could come up with was timing 1 billion
cache cold stat operations with the user namespace code enabled. This
went from 156s to 164s on my laptop (or 156ns to 164ns per stat
operation).

- (uid_t)-1 and (gid_t)-1 are reserved as an internal error value. Most
uid/gid setting system calls treat these value specially anyway so
attempting to use -1 as a uid would likely cause entertaining failures
in userspace.

- If setuid is called with a uid that can not be mapped setuid fails. I
have looked at sendmail, login, ssh and every other program I could
think of that would call setuid and they all check for and handle the
case where setuid fails.

- If stat or a similar system call is called from a context in which we
can not map a uid we lie and return overflowuid. The LFS experience
suggests not lying and returning an error code might be better, but
the historical precedent with uids is different and I can not think
of anything that would break by lying about a uid we can't map.

- Capabilities are localized to the current user namespace making it
safe to give the initial user in a user namespace all capabilities.

My git tree covers all of the modifications needed to convert the core
kernel and enough changes to make a system bootable to runlevel 1.

Eric W. Biederman (45):
vfs: Don't allow a user namespace root to make device nodes
userns: Kill bogus declaration of function release_uids
userns: Replace netlink uses of cap_raised with capable.
userns: Remove unnecessary cast to struct user_struct when copying cred->user.
cred: Add forward declaration of init_user_ns in all cases.
userns: Use cred->user_ns instead of cred->user->user_ns
cred: Refcount the user_ns pointed to by the cred.
userns: Add an explicit reference to the parent user namespace
mqueue: Explicitly capture the user namespace to send the notification to.
userns: Deprecate and rename the user_namespace reference in the user_struct
userns: Start out with a full set of capabilities.
userns: Replace the hard to write inode_userns with inode_capable.
userns: Add kuid_t and kgid_t and associated infrastructure in uidgid.h
userns: Add a Kconfig option to enforce strict kuid and kgid type checks
userns: Disassociate user_struct from the user_namespace.
userns: Simplify the user_namespace by making userns->creator a kuid.
userns: Rework the user_namespace adding uid/gid mapping support
userns: Convert group_info values from gid_t to kgid_t.
userns: Store uid and gid values in struct cred with kuid_t and kgid_t types
userns: Replace user_ns_map_uid and user_ns_map_gid with from_kuid and from_kgid
userns: Convert sched_set_affinity and sched_set_scheduler's permission checks
userns: Convert capabilities related permsion checks
userns: Convert setting and getting uid and gid system calls to use kuid and kgid
userns: Convert ptrace, kill, set_priority permission checks to work with kuids and kgids
userns: Store uid and gid types in vfs structures with kuid_t and kgid_t types
userns: Convert in_group_p and in_egroup_p to use kgid_t
userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs
userns: Convert user specfied uids and gids in chown into kuids and kgid
userns: Convert stat to return values mapped from kuids and kgids
userns: Fail exec for suid and sgid binaries with ids outside our user namespace.
userns: Teach inode_capable to understand inodes whose uids map to other namespaces.
userns: signal remove unnecessary map_cred_ns
userns: Add negative depends on entries to avoid building code that is userns unsafe
userns: Convert binary formats to use kuid/kgid where appropriate
userns: Convert devpts to use kuid/kgid where appropriate
userns: Convert ext2 to use kuid/kgid where appropriate.
userns: Convert ext3 to use kuid/kgid where appropriate
userns: Convert ext4 to user kuid/kgid where appropriate
userns: Convert proc to use kuid/kgid where appropriate
userns: Convert sysctl permission checks to use kuid and kgids.
userns: Convert sysfs to use kgid/kuid where appropriate
userns: Convert tmpfs to use kuid and kgid where appropriate
userns: Convert cgroup permission checks to use uid_eq
userns: Convert the move_pages, and migrate_pages permission checks to use uid_eq
userns: Silence silly gcc warning.

Sasha Levin (1):
cred: use correct cred accessor with regards to rcu read lock

arch/arm/kernel/sys_oabi-compat.c | 4 +-
arch/parisc/hpux/fs.c | 4 +-
arch/s390/kernel/compat_linux.c | 18 +-
arch/sparc/kernel/sys_sparc32.c | 4 +-
arch/x86/ia32/sys_ia32.c | 4 +-
arch/x86/mm/fault.c | 2 +-
drivers/block/drbd/drbd_nl.c | 2 +-
drivers/md/dm-log-userspace-transfer.c | 2 +-
drivers/video/uvesafb.c | 2 +-
fs/attr.c | 8 +-
fs/binfmt_elf.c | 12 +-
fs/binfmt_elf_fdpic.c | 12 +-
fs/compat.c | 4 +-
fs/devpts/inode.c | 24 +-
fs/ecryptfs/messaging.c | 2 +-
fs/exec.c | 15 +-
fs/ext2/balloc.c | 5 +-
fs/ext2/ext2.h | 8 +-
fs/ext2/inode.c | 20 +-
fs/ext2/super.c | 31 ++-
fs/ext3/balloc.c | 5 +-
fs/ext3/ext3.h | 8 +-
fs/ext3/inode.c | 32 +-
fs/ext3/super.c | 35 ++-
fs/ext4/balloc.c | 4 +-
fs/ext4/ext4.h | 4 +-
fs/ext4/ialloc.c | 4 +-
fs/ext4/inode.c | 34 +-
fs/ext4/migrate.c | 4 +-
fs/ext4/super.c | 38 ++-
fs/fcntl.c | 6 +-
fs/inode.c | 10 +-
fs/ioprio.c | 18 +-
fs/locks.c | 2 +-
fs/namei.c | 29 +-
fs/nfsd/auth.c | 5 +-
fs/open.c | 16 +-
fs/proc/array.c | 15 +-
fs/proc/base.c | 93 +++++-
fs/proc/inode.c | 4 +-
fs/proc/proc_sysctl.c | 4 +-
fs/proc/root.c | 2 +-
fs/stat.c | 12 +-
fs/sysfs/inode.c | 4 +-
include/linux/capability.h | 2 +
include/linux/cred.h | 33 +-
include/linux/fs.h | 42 ++-
include/linux/pid_namespace.h | 2 +-
include/linux/proc_fs.h | 4 +-
include/linux/quotaops.h | 4 +-
include/linux/sched.h | 9 +-
include/linux/shmem_fs.h | 4 +-
include/linux/stat.h | 5 +-
include/linux/uidgid.h | 200 +++++++++++
include/linux/user_namespace.h | 39 +-
include/trace/events/ext3.h | 4 +-
include/trace/events/ext4.h | 4 +-
init/Kconfig | 130 +++++++-
ipc/mqueue.c | 10 +-
ipc/namespace.c | 2 +-
kernel/capability.c | 21 ++
kernel/cgroup.c | 6 +-
kernel/cred.c | 44 ++-
kernel/exit.c | 6 +-
kernel/groups.c | 50 ++--
kernel/ptrace.c | 15 +-
kernel/sched/core.c | 7 +-
kernel/signal.c | 51 +--
kernel/sys.c | 266 ++++++++++-----
kernel/timer.c | 8 +-
kernel/uid16.c | 48 ++-
kernel/user.c | 51 ++-
kernel/user_namespace.c | 595 ++++++++++++++++++++++++++++----
kernel/utsname.c | 2 +-
mm/mempolicy.c | 4 +-
mm/migrate.c | 4 +-
mm/oom_kill.c | 4 +-
mm/shmem.c | 22 +-
net/core/sock.c | 4 +-
net/ipv4/ping.c | 11 +-
net/sunrpc/auth_generic.c | 4 +-
net/sunrpc/auth_gss/svcauth_gss.c | 7 +-
net/sunrpc/auth_unix.c | 15 +-
net/sunrpc/svcauth_unix.c | 18 +-
security/commoncap.c | 61 ++--
security/keys/key.c | 2 +-
security/keys/permission.c | 5 +-
security/keys/process_keys.c | 2 +-
88 files changed, 1790 insertions(+), 608 deletions(-)