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Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Add a new internal Kconfig option UIDGID_CONVERTED that is true when the selected
Kconfig options have been converted to be user namespace safe, and guard
USER_NS and guard the UIDGID_STRICT_TYPE_CHECK options with it.
This keeps innocent kernel users from having the choice to enable
the user namespace in the cases where it is known not to work.
Most of the rest of the conversions are simple and straight forward but
their sheer number means it is good not to count on having them all done
and reviwed before thinking of merging this code.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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map_cred_ns is a light wrapper around from_kuid with the order of the arguments
reversed. Replace map_cred_ns with from_kuid and remove map_cred_ns.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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- Store uids and gids with kuid_t and kgid_t in struct kstat
- Convert uid and gids to userspace usable values with
from_kuid and from_kgid
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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The conversion of all of the users is not done yet there are too many to change
in one go and leave the code reviewable. For now I change just the header and
a few trivial users and rely on CONFIG_UIDGID_STRICT_TYPE_CHECKS not being set
to ensure that the code will still compile during the transition.
Helper functions i_uid_read, i_uid_write, i_gid_read, i_gid_write are added
so that in most cases filesystems can avoid the complexities of multiple user
namespaces and can concentrate on moving their raw numeric values into and
out of the vfs data structures.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Update the permission checks to use the new uid_eq and gid_eq helpers
and remove the now unnecessary user_ns equality comparison.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Convert setregid, setgid, setreuid, setuid,
setresuid, getresuid, setresgid, getresgid, setfsuid, setfsgid,
getuid, geteuid, getgid, getegid,
waitpid, waitid, wait4.
Convert userspace uids and gids into kuids and kgids before
being placed on struct cred. Convert struct cred kuids and
kgids into userspace uids and gids when returning them.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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- Use uid_eq when comparing kuids
Use gid_eq when comparing kgids
- Use make_kuid(user_ns, 0) to talk about the user_namespace root uid
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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- Compare kuids with uid_eq
- kuid are uniuqe across all user namespaces so there is no longer the
need for a user_namespace comparison.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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These function are no longer needed replace them with their more useful equivalents.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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cred.h and a few trivial users of struct cred are changed. The rest of the users
of struct cred are left for other patches as there are too many changes to make
in one go and leave the change reviewable. If the user namespace is disabled and
CONFIG_UIDGID_STRICT_TYPE_CHECKS are disabled the code will contiue to compile
and behave correctly.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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As a first step to converting struct cred to be all kuid_t and kgid_t
values convert the group values stored in group_info to always be
kgid_t values. Unless user namespaces are used this change should
have no effect.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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- Convert the old uid mapping functions into compatibility wrappers
- Add a uid/gid mapping layer from user space uid and gids to kernel
internal uids and gids that is extent based for simplicty and speed.
* Working with number space after mapping uids/gids into their kernel
internal version adds only mapping complexity over what we have today,
leaving the kernel code easy to understand and test.
- Add proc files /proc/self/uid_map /proc/self/gid_map
These files display the mapping and allow a mapping to be added
if a mapping does not exist.
- Allow entering the user namespace without a uid or gid mapping.
Since we are starting with an existing user our uids and gids
still have global mappings so are still valid and useful they just don't
have local mappings. The requirement for things to work are global uid
and gid so it is odd but perfectly fine not to have a local uid
and gid mapping.
Not requiring global uid and gid mappings greatly simplifies
the logic of setting up the uid and gid mappings by allowing
the mappings to be set after the namespace is created which makes the
slight weirdness worth it.
- Make the mappings in the initial user namespace to the global
uid/gid space explicit. Today it is an identity mapping
but in the future we may want to twist this for debugging, similar
to what we do with jiffies.
- Document the memory ordering requirements of setting the uid and
gid mappings. We only allow the mappings to be set once
and there are no pointers involved so the requirments are
trivial but a little atypical.
Performance:
In this scheme for the permission checks the performance is expected to
stay the same as the actuall machine instructions should remain the same.
The worst case I could think of is ls -l on a large directory where
all of the stat results need to be translated with from kuids and
kgids to uids and gids. So I benchmarked that case on my laptop
with a dual core hyperthread Intel i5-2520M cpu with 3M of cpu cache.
My benchmark consisted of going to single user mode where nothing else
was running. On an ext4 filesystem opening 1,000,000 files and looping
through all of the files 1000 times and calling fstat on the
individuals files. This was to ensure I was benchmarking stat times
where the inodes were in the kernels cache, but the inode values were
not in the processors cache. My results:
v3.4-rc1: ~= 156ns (unmodified v3.4-rc1 with user namespace support disabled)
v3.4-rc1-userns-: ~= 155ns (v3.4-rc1 with my user namespace patches and user namespace support disabled)
v3.4-rc1-userns+: ~= 164ns (v3.4-rc1 with my user namespace patches and user namespace support enabled)
All of the configurations ran in roughly 120ns when I performed tests
that ran in the cpu cache.
So in summary the performance impact is:
1ns improvement in the worst case with user namespace support compiled out.
8ns aka 5% slowdown in the worst case with user namespace support compiled in.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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- Transform userns->creator from a user_struct reference to a simple
kuid_t, kgid_t pair.
In cap_capable this allows the check to see if we are the creator of
a namespace to become the classic suser style euid permission check.
This allows us to remove the need for a struct cred in the mapping
functions and still be able to dispaly the user namespace creators
uid and gid as 0.
- Remove the now unnecessary delayed_work in free_user_ns.
All that is left for free_user_ns to do is to call kmem_cache_free
and put_user_ns. Those functions can be called in any context
so call them directly from free_user_ns removing the need for delayed work.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Modify alloc_uid to take a kuid and make the user hash table global.
Stop holding a reference to the user namespace in struct user_struct.
This simplifies the code and makes the per user accounting not
care about which user namespace a uid happens to appear in.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Make it possible to easily switch between strong mandatory
type checks and relaxed type checks so that the code can
easily be tested with the type checks and then built
with the strong type checks disabled so the resulting
code can be used.
Require strong mandatory type checks when enabling the user namespace.
It is very simple to make a typo and use the wrong type allowing
conversions to/from userspace values to be bypassed by accident,
the strong type checks prevent this.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Start distinguishing between internal kernel uids and gids and
values that userspace can use. This is done by introducing two
new types: kuid_t and kgid_t. These types and their associated
functions are infrastructure are declared in the new header
uidgid.h.
Ultimately there will be a different implementation of the mapping
functions for use with user namespaces. But to keep it simple
we introduce the mapping functions first to separate the meat
from the mechanical code conversions.
Export overflowuid and overflowgid so we can use from_kuid_munged
and from_kgid_munged in modular code.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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This represents a change in strategy of how to handle user namespaces.
Instead of tagging everything explicitly with a user namespace and bulking
up all of the comparisons of uids and gids in the kernel, all uids and gids
in use will have a mapping to a flat kuid and kgid spaces respectively. This
allows much more of the existing logic to be preserved and in general
allows for faster code.
In this new and improved world we allow someone to utiliize capabilities
over an inode if the inodes owner mapps into the capabilities holders user
namespace and the user has capabilities in their user namespace. Which
is simple and efficient.
Moving the fs uid comparisons to be comparisons in a flat kuid space
follows in later patches, something that is only significant if you
are using user namespaces.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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With a user_ns reference in struct cred the only user of the user namespace
reference in struct user_struct is to keep the uid hash table alive.
The user_namespace reference in struct user_struct will be going away soon, and
I have removed all of the references. Rename the field from user_ns to _user_ns
so that the compiler can verify nothing follows the user struct to the user
namespace anymore.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Stop relying on user->user_ns which is going away and instead capture
the user_namespace of the process we are supposed to notify.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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I am about to remove the struct user_namespace reference from struct user_struct.
So keep an explicit track of the parent user namespace.
Take advantage of this new reference and replace instances of user_ns->creator->user_ns
with user_ns->parent.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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struct user_struct will shortly loose it's user_ns reference
so make the cred user_ns reference a proper reference complete
with reference counting.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Optimize performance and prepare for the removal of the user_ns reference
from user_struct. Remove the slow long walk through cred->user->user_ns and
instead go straight to cred->user_ns.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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In struct cred the user member is and has always been declared struct user_struct *user.
At most a constant struct cred will have a constant pointer to non-constant user_struct
so remove this unnecessary cast.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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In 2009 Philip Reiser notied that a few users of netlink connector
interface needed a capability check and added the idiom
cap_raised(nsp->eff_cap, CAP_SYS_ADMIN) to a few of them, on the premise
that netlink was asynchronous.
In 2011 Patrick McHardy noticed we were being silly because netlink is
synchronous and removed eff_cap from the netlink_skb_params and changed
the idiom to cap_raised(current_cap(), CAP_SYS_ADMIN).
Looking at those spots with a fresh eye we should be calling
capable(CAP_SYS_ADMIN). The only reason I can see for not calling
capable is that it once appeared we were not in the same task as the
caller which would have made calling capable() impossible.
In the initial user_namespace the only difference between between
cap_raised(current_cap(), CAP_SYS_ADMIN) and capable(CAP_SYS_ADMIN)
are a few sanity checks and the fact that capable(CAP_SYS_ADMIN)
sets PF_SUPERPRIV if we use the capability.
Since we are going to be using root privilege setting PF_SUPERPRIV
seems the right thing to do.
The motivation for this that patch is that in a child user namespace
cap_raised(current_cap(),...) tests your capabilities with respect to
that child user namespace not capabilities in the initial user namespace
and thus will allow processes that should be unprivielged to use the
kernel services that are only protected with
cap_raised(current_cap(),..).
To fix possible user_namespace issues and to just clean up the code
replace cap_raised(current_cap(), CAP_SYS_ADMIN) with
capable(CAP_SYS_ADMIN).
Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Acked-by: Andrew G. Morgan <morgan@kernel.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Serge E. Hallyn <serge.hallyn@canonical.com>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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There is no release_uids function remove the declaration from sched.h
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Safely making device nodes in a container is solvable but simply
having the capability in a user namespace is not sufficient to make
this work.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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64252c75a2196a0cf1e0d3777143ecfe0e3ae650 "vfs: remove dget() from
dentry_unhash()" changed the implementation but not the comment.
Cc: Sage Weil <sage@newdream.net>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Split __lookup_hash into two component functions:
lookup_dcache - tries cached lookup, returns whether real lookup is needed
lookup_real - calls i_op->lookup
This eliminates code duplication between d_alloc_and_lookup() and
d_inode_lookup().
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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now we have __lookup_hash() open-coded if !dentry case;
just call the damn thing instead...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Reorder if-else cases for starters...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Everything arriving into if (!dentry) will have need_reval = 1.
Indeed, the only way to get there with need_reval reset to 0 would
be via
if (unlikely(d_need_lookup(dentry)))
goto unlazy;
if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
status = d_revalidate(dentry, nd);
if (unlikely(status <= 0)) {
if (status != -ECHILD)
need_reval = 0;
goto unlazy;
...
unlazy:
/* no assignments to dentry */
if (dentry && unlikely(d_need_lookup(dentry))) {
dput(dentry);
dentry = NULL;
}
and if d_need_lookup() had already been false the first time around, it
will remain false on the second call as well.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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d_lookup() *will* fail after successful d_invalidate(), if we are
holding i_mutex all along. IOW, we don't need to jump back to
l: - we know what path will be taken there and can do that (i.e.
d_alloc_and_lookup()) directly.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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keep holding ->i_mutex over revalidation parts
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Duplicate the revalidation-related parts into if (!dentry) branch.
Next step will be to pull them under i_mutex.
This and the next 8 commits are more or less a splitup of patch
by Miklos; folks, when you are working with something that convoluted,
carve your patches up into easily reviewed steps, especially when
a lot of codepaths involved are rarely hit...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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The only caller of __lookup_hash() that needs the exec permission check on
parent is lookup_one_len().
All lookup_hash() callers already checked permission in LOOKUP_PARENT walk.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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__lookup_hash() calls ->lookup() if the dentry needs lookup and on success
revalidates the dentry (all under dir->i_mutex).
While this is harmless it doesn't make a lot of sense.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Eric W. Biederman
Linus Torvalds
J. Bruce Fields
Miklos Szeredi
Al Viro