kernel_replicant_linux/security/selinux, branch replicant-11

FROMLIST: Add flags option to get xattr method paired to __vfs_getxattr

2021-11-25T10:04:46+00:00

Add a flag option to get xattr method that could have a bit flag of
XATTR_NOSECURITY passed to it.  XATTR_NOSECURITY is generally then
set in the __vfs_getxattr path when called by security
infrastructure.

This handles the case of a union filesystem driver that is being
requested by the security layer to report back the xattr data.

For the use case where access is to be blocked by the security layer.

The path then could be security(dentry) ->
__vfs_getxattr(dentry...XATTR_NOSECURITY) ->
handler->get(dentry...XATTR_NOSECURITY) ->
__vfs_getxattr(lower_dentry...XATTR_NOSECURITY) ->
lower_handler->get(lower_dentry...XATTR_NOSECURITY)
which would report back through the chain data and success as
expected, the logging security layer at the top would have the
data to determine the access permissions and report back the target
context that was blocked.

Without the get handler flag, the path on a union filesystem would be
the errant security(dentry) -> __vfs_getxattr(dentry) ->
handler->get(dentry) -> vfs_getxattr(lower_dentry) -> nested ->
security(lower_dentry, log off) -> lower_handler->get(lower_dentry)
which would report back through the chain no data, and -EACCES.

For selinux for both cases, this would translate to a correctly
determined blocked access. In the first case with this change a correct avc
log would be reported, in the second legacy case an incorrect avc log
would be reported against an uninitialized u:object_r:unlabeled:s0
context making the logs cosmetically useless for audit2allow.

This patch series is inert and is the wide-spread addition of the
flags option for xattr functions, and a replacement of __vfs_getxattr
with __vfs_getxattr(...XATTR_NOSECURITY).

Signed-off-by: Mark Salyzyn 
Reviewed-by: Jan Kara 
Acked-by: Jan Kara 
Acked-by: Jeff Layton 
Acked-by: David Sterba 
Acked-by: Darrick J. Wong 
Acked-by: Mike Marshall 
Cc: Stephen Smalley 
Cc: linux-kernel@vger.kernel.org
Cc: kernel-team@android.com
Cc: linux-security-module@vger.kernel.org

(cherry picked from (rejected from archive because of too many recipients))
Signed-off-by: Mark Salyzyn 
Bug: 133515582
Bug: 136124883
Bug: 129319403
Change-Id: Iabbb8771939d5f66667a26bb23ddf4c562c349a1

selinux: correct the return value when loads initial sids

2021-08-12T11:22:16+00:00

commit 4c156084daa8ee70978e4b150b5eb5fc7b1f15be upstream.

It should not return 0 when SID 0 is assigned to isids.
This patch fixes it.

Cc: stable@vger.kernel.org
Fixes: e3e0b582c321a ("selinux: remove unused initial SIDs and improve handling")
Signed-off-by: Xiu Jianfeng 
[PM: remove changelog from description]
Signed-off-by: Paul Moore 
Signed-off-by: Greg Kroah-Hartman

selinux: use __GFP_NOWARN with GFP_NOWAIT in the AVC

2021-07-19T07:44:49+00:00

[ Upstream commit 648f2c6100cfa18e7dfe43bc0b9c3b73560d623c ]

In the field, we have seen lots of allocation failure from the call
path below.

06-03 13:29:12.999 1010315 31557 31557 W Binder  : 31542_2: page allocation failure: order:0, mode:0x800(GFP_NOWAIT), nodemask=(null),cpuset=background,mems_allowed=0
...
...
06-03 13:29:12.999 1010315 31557 31557 W Call trace:
06-03 13:29:12.999 1010315 31557 31557 W         : dump_backtrace.cfi_jt+0x0/0x8
06-03 13:29:12.999 1010315 31557 31557 W         : dump_stack+0xc8/0x14c
06-03 13:29:12.999 1010315 31557 31557 W         : warn_alloc+0x158/0x1c8
06-03 13:29:12.999 1010315 31557 31557 W         : __alloc_pages_slowpath+0x9d8/0xb80
06-03 13:29:12.999 1010315 31557 31557 W         : __alloc_pages_nodemask+0x1c4/0x430
06-03 13:29:12.999 1010315 31557 31557 W         : allocate_slab+0xb4/0x390
06-03 13:29:12.999 1010315 31557 31557 W         : ___slab_alloc+0x12c/0x3a4
06-03 13:29:12.999 1010315 31557 31557 W         : kmem_cache_alloc+0x358/0x5e4
06-03 13:29:12.999 1010315 31557 31557 W         : avc_alloc_node+0x30/0x184
06-03 13:29:12.999 1010315 31557 31557 W         : avc_update_node+0x54/0x4f0
06-03 13:29:12.999 1010315 31557 31557 W         : avc_has_extended_perms+0x1a4/0x460
06-03 13:29:12.999 1010315 31557 31557 W         : selinux_file_ioctl+0x320/0x3d0
06-03 13:29:12.999 1010315 31557 31557 W         : __arm64_sys_ioctl+0xec/0x1fc
06-03 13:29:12.999 1010315 31557 31557 W         : el0_svc_common+0xc0/0x24c
06-03 13:29:12.999 1010315 31557 31557 W         : el0_svc+0x28/0x88
06-03 13:29:12.999 1010315 31557 31557 W         : el0_sync_handler+0x8c/0xf0
06-03 13:29:12.999 1010315 31557 31557 W         : el0_sync+0x1a4/0x1c0
..
..
06-03 13:29:12.999 1010315 31557 31557 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:12.999 1010315 31557 31557 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:12.999 1010315 31557 31557 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:12.999 1010161 10686 10686 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:12.999 1010161 10686 10686 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:12.999 1010161 10686 10686 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:12.999 1010161 10686 10686 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:12.999 1010161 10686 10686 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:12.999 1010161 10686 10686 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:12.999 1010161 10686 10686 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:12.999 1010161 10686 10686 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:12.999 1010161 10686 10686 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:13.000 1010161 10686 10686 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:13.000 1010161 10686 10686 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:13.000 1010161 10686 10686 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:13.000 1010161 10686 10686 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:13.000 1010161 10686 10686 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:13.000 1010161 10686 10686 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:13.000 1010161 10686 10686 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:13.000 1010161 10686 10686 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:13.000 1010161 10686 10686 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:13.000 10230 30892 30892 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:13.000 10230 30892 30892 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:13.000 10230 30892 30892 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:13.000 10230 30892 30892 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:13.000 10230 30892 30892 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0

Based on [1], selinux is tolerate for failure of memory allocation.
Then, use __GFP_NOWARN together.

[1] 476accbe2f6e ("selinux: use GFP_NOWAIT in the AVC kmem_caches")

Signed-off-by: Minchan Kim 
[PM: subj fix, line wraps, normalized commit refs]
Signed-off-by: Paul Moore 
Signed-off-by: Sasha Levin

selinux: add proper NULL termination to the secclass_map permissions

2021-05-14T07:49:59+00:00

commit e4c82eafb609c2badc56f4e11bc50fcf44b8e9eb upstream.

This patch adds the missing NULL termination to the "bpf" and
"perf_event" object class permission lists.

This missing NULL termination should really only affect the tools
under scripts/selinux, with the most important being genheaders.c,
although in practice this has not been an issue on any of my dev/test
systems.  If the problem were to manifest itself it would likely
result in bogus permissions added to the end of the object class;
thankfully with no access control checks using these bogus
permissions and no policies defining these permissions the impact
would likely be limited to some noise about undefined permissions
during policy load.

Cc: stable@vger.kernel.org
Fixes: ec27c3568a34 ("selinux: bpf: Add selinux check for eBPF syscall operations")
Fixes: da97e18458fb ("perf_event: Add support for LSM and SELinux checks")
Signed-off-by: Paul Moore 
Signed-off-by: Greg Kroah-Hartman

selinux: fix race between old and new sidtab

2021-04-14T06:41:57+00:00

commit 9ad6e9cb39c66366bf7b9aece114aca277981a1f upstream.

Since commit 1b8b31a2e612 ("selinux: convert policy read-write lock to
RCU"), there is a small window during policy load where the new policy
pointer has already been installed, but some threads may still be
holding the old policy pointer in their read-side RCU critical sections.
This means that there may be conflicting attempts to add a new SID entry
to both tables via sidtab_context_to_sid().

See also (and the rest of the thread):
https://lore.kernel.org/selinux/CAFqZXNvfux46_f8gnvVvRYMKoes24nwm2n3sPbMjrB8vKTW00g@mail.gmail.com/

Fix this by installing the new policy pointer under the old sidtab's
spinlock along with marking the old sidtab as "frozen". Then, if an
attempt to add new entry to a "frozen" sidtab is detected, make
sidtab_context_to_sid() return -ESTALE to indicate that a new policy
has been installed and that the caller will have to abort the policy
transaction and try again after re-taking the policy pointer (which is
guaranteed to be a newer policy). This requires adding a retry-on-ESTALE
logic to all callers of sidtab_context_to_sid(), but fortunately these
are easy to determine and aren't that many.

This seems to be the simplest solution for this problem, even if it
looks somewhat ugly. Note that other places in the kernel (e.g.
do_mknodat() in fs/namei.c) use similar stale-retry patterns, so I think
it's reasonable.

Cc: stable@vger.kernel.org
Fixes: 1b8b31a2e612 ("selinux: convert policy read-write lock to RCU")
Signed-off-by: Ondrej Mosnacek 
Signed-off-by: Paul Moore 
Signed-off-by: Greg Kroah-Hartman

selinux: fix cond_list corruption when changing booleans

2021-04-14T06:41:57+00:00

commit d8f5f0ea5b86300390b026b6c6e7836b7150814a upstream.

Currently, duplicate_policydb_cond_list() first copies the whole
conditional avtab and then tries to link to the correct entries in
cond_dup_av_list() using avtab_search(). However, since the conditional
avtab may contain multiple entries with the same key, this approach
often fails to find the right entry, potentially leading to wrong rules
being activated/deactivated when booleans are changed.

To fix this, instead start with an empty conditional avtab and add the
individual entries one-by-one while building the new av_lists. This
approach leads to the correct result, since each entry is present in the
av_lists exactly once.

The issue can be reproduced with Fedora policy as follows:

    # sesearch -s ftpd_t -t public_content_rw_t -c dir -p create -A
    allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True
    allow ftpd_t public_content_rw_t:dir { add_name create link remove_name rename reparent rmdir setattr unlink watch watch_reads write }; [ ftpd_anon_write ]:True
    # setsebool ftpd_anon_write=off ftpd_connect_all_unreserved=off ftpd_connect_db=off ftpd_full_access=off

On fixed kernels, the sesearch output is the same after the setsebool
command:

    # sesearch -s ftpd_t -t public_content_rw_t -c dir -p create -A
    allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True
    allow ftpd_t public_content_rw_t:dir { add_name create link remove_name rename reparent rmdir setattr unlink watch watch_reads write }; [ ftpd_anon_write ]:True

While on the broken kernels, it will be different:

    # sesearch -s ftpd_t -t public_content_rw_t -c dir -p create -A
    allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True
    allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True
    allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True

While there, also simplify the computation of nslots. This changes the
nslots values for nrules 2 or 3 to just two slots instead of 4, which
makes the sequence more consistent.

Cc: stable@vger.kernel.org
Fixes: c7c556f1e81b ("selinux: refactor changing booleans")
Signed-off-by: Ondrej Mosnacek 
Signed-off-by: Paul Moore 
Signed-off-by: Greg Kroah-Hartman

selinux: make nslot handling in avtab more robust

2021-04-14T06:41:57+00:00

commit 442dc00f82a9727dc0c48c44f792c168f593c6df upstream.

1. Make sure all fileds are initialized in avtab_init().
2. Slightly refactor avtab_alloc() to use the above fact.
3. Use h->nslot == 0 as a sentinel in the access functions to prevent
   dereferencing h->htable when it's not allocated.

Cc: stable@vger.kernel.org
Signed-off-by: Ondrej Mosnacek 
Signed-off-by: Paul Moore 
Signed-off-by: Greg Kroah-Hartman

selinux: fix variable scope issue in live sidtab conversion

2021-03-30T12:31:53+00:00

commit 6406887a12ee5dcdaffff1a8508d91113d545559 upstream.

Commit 02a52c5c8c3b ("selinux: move policy commit after updating
selinuxfs") moved the selinux_policy_commit() call out of
security_load_policy() into sel_write_load(), which caused a subtle yet
rather serious bug.

The problem is that security_load_policy() passes a reference to the
convert_params local variable to sidtab_convert(), which stores it in
the sidtab, where it may be accessed until the policy is swapped over
and RCU synchronized. Before 02a52c5c8c3b, selinux_policy_commit() was
called directly from security_load_policy(), so the convert_params
pointer remained valid all the way until the old sidtab was destroyed,
but now that's no longer the case and calls to sidtab_context_to_sid()
on the old sidtab after security_load_policy() returns may cause invalid
memory accesses.

This can be easily triggered using the stress test from commit
ee1a84fdfeed ("selinux: overhaul sidtab to fix bug and improve
performance"):
```
function rand_cat() {
	echo $(( $RANDOM % 1024 ))
}

function do_work() {
	while true; do
		echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
			>/sys/fs/selinux/context 2>/dev/null || true
	done
}

do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &

while load_policy; do echo -n .; sleep 0.1; done

kill %1
kill %2
kill %3
```

Fix this by allocating the temporary sidtab convert structures
dynamically and passing them among the
selinux_policy_{load,cancel,commit} functions.

Fixes: 02a52c5c8c3b ("selinux: move policy commit after updating selinuxfs")
Cc: stable@vger.kernel.org
Tested-by: Tyler Hicks 
Reviewed-by: Tyler Hicks 
Signed-off-by: Ondrej Mosnacek 
[PM: merge fuzz in security.h and services.c]
Signed-off-by: Paul Moore 
Signed-off-by: Greg Kroah-Hartman

selinux: don't log MAC_POLICY_LOAD record on failed policy load

2021-03-30T12:31:53+00:00

commit 519dad3bcd809dc1523bf80ab0310ddb3bf00ade upstream.

If sel_make_policy_nodes() fails, we should jump to 'out', not 'out1',
as the latter would incorrectly log an MAC_POLICY_LOAD audit record,
even though the policy hasn't actually been reloaded. The 'out1' jump
label now becomes unused and can be removed.

Fixes: 02a52c5c8c3b ("selinux: move policy commit after updating selinuxfs")
Cc: stable@vger.kernel.org
Signed-off-by: Ondrej Mosnacek 
Signed-off-by: Paul Moore 
Signed-off-by: Greg Kroah-Hartman

selinux: fix inconsistency between inode_getxattr and inode_listsecurity

2021-03-04T10:38:28+00:00

commit a9ffe682c58aaff643764547f5420e978b6e0830 upstream.

When inode has no listxattr op of its own (e.g. squashfs) vfs_listxattr
calls the LSM inode_listsecurity hooks to list the xattrs that LSMs will
intercept in inode_getxattr hooks.

When selinux LSM is installed but not initialized, it will list the
security.selinux xattr in inode_listsecurity, but will not intercept it
in inode_getxattr.  This results in -ENODATA for a getxattr call for an
xattr returned by listxattr.

This situation was manifested as overlayfs failure to copy up lower
files from squashfs when selinux is built-in but not initialized,
because ovl_copy_xattr() iterates the lower inode xattrs by
vfs_listxattr() and vfs_getxattr().

Match the logic of inode_listsecurity to that of inode_getxattr and
do not list the security.selinux xattr if selinux is not initialized.

Reported-by: Michael Labriola 
Tested-by: Michael Labriola 
Link: https://lore.kernel.org/linux-unionfs/2nv9d47zt7.fsf@aldarion.sourceruckus.org/
Fixes: c8e222616c7e ("selinux: allow reading labels before policy is loaded")
Cc: stable@vger.kernel.org#v5.9+
Signed-off-by: Amir Goldstein 
Reviewed-by: Ondrej Mosnacek 
Signed-off-by: Paul Moore 
Signed-off-by: Greg Kroah-Hartman