kernel/linux.git/security/smack/smack_access.c, branch linux-4.4.y

Smack: Fix wrong semantics in smk_access_entry()

2021-09-22T09:41:24+00:00

[ Upstream commit 6d14f5c7028eea70760df284057fe198ce7778dd ] In the smk_access_entry() function, if no matching rule is found in the rust_list, a negative error code will be used to perform bit operations with the MAY_ enumeration value. This is semantically wrong. This patch fixes this issue. Signed-off-by: Tianjia Zhang Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin

smack: use GFP_NOFS while holding inode_smack::smk_lock

2019-10-07T19:01:07+00:00

commit e5bfad3d7acc5702f32aafeb388362994f4d7bd0 upstream. inode_smack::smk_lock is taken during smack_d_instantiate(), which is called during a filesystem transaction when creating a file on ext4. Therefore to avoid a deadlock, all code that takes this lock must use GFP_NOFS, to prevent memory reclaim from waiting for the filesystem transaction to complete. Reported-by: syzbot+0eefc1e06a77d327a056@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers Signed-off-by: Casey Schaufler Signed-off-by: Greg Kroah-Hartman

Smack: limited capability for changing process label

2015-10-19T19:06:47+00:00

This feature introduces new kernel interface: - /relabel-self - for setting transition labels list This list is used to control smack label transition mechanism. List is set by, and per process. Process can transit to new label only if label is on the list. Only process with CAP_MAC_ADMIN capability can add labels to this list. With this list, process can change it's label without CAP_MAC_ADMIN but only once. After label changing, list is unset. Changes in v2: * use list_for_each_entry instead of _rcu during label write * added missing description in security/Smack.txt Changes in v3: * squashed into one commit Changes in v4: * switch from global list to per-task list * since the per-task list is accessed only by the task itself there is no need to use synchronization mechanisms on it Changes in v5: * change smackfs interface of relabel-self to the one used for onlycap multiple labels are accepted, separated by space, which replace the previous list upon write Signed-off-by: Zbigniew Jasinski Signed-off-by: Rafal Krypa Acked-by: Casey Schaufler

Kernel threads excluded from smack checks

2015-08-10T22:15:50+00:00

Adds an ignore case for kernel tasks, so that they can access all resources. Since kernel worker threads are spawned with floor label, they are severely restricted by Smack policy. It is not an issue without onlycap, as these processes also run with root, so CAP_MAC_OVERRIDE kicks in. But with onlycap turned on, there is no way to change the label for these processes. Signed-off-by: Roman Kubiak Acked-by: Casey Schaufler

Smack: allow multiple labels in onlycap

2015-06-02T18:53:42+00:00

Smack onlycap allows limiting of CAP_MAC_ADMIN and CAP_MAC_OVERRIDE to processes running with the configured label. But having single privileged label is not enough in some real use cases. On a complex system like Tizen, there maybe few programs that need to configure Smack policy in run-time and running them all with a single label is not always practical. This patch extends onlycap feature for multiple labels. They are configured in the same smackfs "onlycap" interface, separated by spaces. Signed-off-by: Rafal Krypa

smack: pass error code through pointers

2015-05-15T15:36:03+00:00

This patch makes the following functions to use ERR_PTR() and related macros to pass the appropriate error code through returned pointers: smk_parse_smack() smk_import_entry() smk_fetch() It also makes all the other functions that use them to handle the error cases properly. This ways correct error codes from places where they happened can be propagated to the user space if necessary. Doing this it fixes a bug in onlycap and unconfined files handling. Previously their content was cleared on any error from smk_import_entry/smk_parse_smack, be it EINVAL (as originally intended) or ENOMEM. Right now it only reacts on EINVAL passing other codes properly to userspace. Comments have been updated accordingly. Signed-off-by: Lukasz Pawelczyk

Smack: Allow an unconfined label in bringup mode

2015-03-23T20:21:34+00:00

I have vehemently opposed adding a "permissive" mode to Smack for the simple reasons that it would be subject to massive abuse and that developers refuse to turn it off come product release. I still believe that this is true, and still refuse to add a general "permissive mode". So don't ask again. Bumjin Im suggested an approach that addresses most of the concerns, and I have implemented it here. I still believe that we'd be better off without this sort of thing, but it looks like this minimizes the abuse potential. Firstly, you have to configure Smack Bringup Mode. That allows for "release" software to be ammune from abuse. Second, only one label gets to be "permissive" at a time. You can use it for debugging, but that's about it. A label written to smackfs/unconfined is treated specially. If either the subject or object label of an access check matches the "unconfined" label, and the access would not have been allowed otherwise an audit record and a console message are generated. The audit record "request" string is marked with either "(US)" or "(UO)", to indicate that the request was granted because of an unconfined label. The fact that an inode was accessed by an unconfined label is remembered, and subsequent accesses to that "impure" object are noted in the log. The impurity is not stored in the filesystem, so a file mislabled as a side effect of using an unconfined label may still cause concern after a reboot. So, it's there, it's dangerous, but so many application developers seem incapable of living without it I have given in. I've tried to make it as safe as I can, but in the end it's still a chain saw. Signed-off-by: Casey Schaufler

security: smack: fix out-of-bounds access in smk_parse_smack()

2014-11-21T21:14:22+00:00

Setting smack label on file (e.g. 'attr -S -s SMACK64 -V "test" test') triggered following spew on the kernel with KASan applied: ================================================================== BUG: AddressSanitizer: out of bounds access in strncpy+0x28/0x60 at addr ffff8800059ad064 ============================================================================= BUG kmalloc-8 (Not tainted): kasan error ----------------------------------------------------------------------------- Disabling lock debugging due to kernel taint INFO: Slab 0xffffea0000166b40 objects=128 used=7 fp=0xffff8800059ad080 flags=0x4000000000000080 INFO: Object 0xffff8800059ad060 @offset=96 fp=0xffff8800059ad080 Bytes b4 ffff8800059ad050: a0 df 9a 05 00 88 ff ff 5a 5a 5a 5a 5a 5a 5a 5a ........ZZZZZZZZ Object ffff8800059ad060: 74 65 73 74 6b 6b 6b a5 testkkk. Redzone ffff8800059ad068: cc cc cc cc cc cc cc cc ........ Padding ffff8800059ad078: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ CPU: 0 PID: 528 Comm: attr Tainted: G B 3.18.0-rc1-mm1+ #5 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 0000000000000000 ffff8800059ad064 ffffffff81534cf2 ffff880005a5bc40 ffffffff8112fe1a 0000000100800006 0000000f059ad060 ffff880006000f90 0000000000000296 ffffea0000166b40 ffffffff8107ca97 ffff880005891060 Call Trace: ? dump_stack (lib/dump_stack.c:52) ? kasan_report_error (mm/kasan/report.c:102 mm/kasan/report.c:178) ? preempt_count_sub (kernel/sched/core.c:2651) ? __asan_load1 (mm/kasan/kasan.h:50 mm/kasan/kasan.c:248 mm/kasan/kasan.c:358) ? strncpy (lib/string.c:121) ? strncpy (lib/string.c:121) ? smk_parse_smack (security/smack/smack_access.c:457) ? setxattr (fs/xattr.c:343) ? smk_import_entry (security/smack/smack_access.c:514) ? smack_inode_setxattr (security/smack/smack_lsm.c:1093 (discriminator 1)) ? security_inode_setxattr (security/security.c:602) ? vfs_setxattr (fs/xattr.c:134) ? setxattr (fs/xattr.c:343) ? setxattr (fs/xattr.c:360) ? get_parent_ip (kernel/sched/core.c:2606) ? preempt_count_sub (kernel/sched/core.c:2651) ? __percpu_counter_add (arch/x86/include/asm/preempt.h:98 lib/percpu_counter.c:90) ? get_parent_ip (kernel/sched/core.c:2606) ? preempt_count_sub (kernel/sched/core.c:2651) ? __mnt_want_write (arch/x86/include/asm/preempt.h:98 fs/namespace.c:359) ? path_setxattr (fs/xattr.c:380) ? SyS_lsetxattr (fs/xattr.c:397) ? system_call_fastpath (arch/x86/kernel/entry_64.S:423) Read of size 1 by task attr: Memory state around the buggy address: ffff8800059ace80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8800059acf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8800059acf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff8800059ad000: 00 fc fc fc 00 fc fc fc 05 fc fc fc 04 fc fc fc ^ ffff8800059ad080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8800059ad100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8800059ad180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== strncpy() copies one byte more than the source string has. Fix this by passing the correct length to strncpy(). Now we can remove initialization of the last byte in 'smack' string because kzalloc() already did this for us. Signed-off-by: Andrey Ryabinin

Smack: Lock mode for the floor and hat labels

2014-10-28T15:22:40+00:00

The lock access mode allows setting a read lock on a file for with the process has only read access. The floor label is defined to make it easy to have the basic system installed such that everyone can read it. Once there's a desire to read lock (rationally or otherwise) a floor file a rule needs to get set. This happens all the time, so make the floor label a little bit more special and allow everyone lock access, too. By implication, give processes with the hat label (hat can read everything) lock access as well. This reduces clutter in the Smack rule set. Signed-off-by: Casey Schaufler

Make Smack operate on smack_known struct where it still used char*

2014-08-29T17:10:55+00:00

Smack used to use a mix of smack_known struct and char* throughout its APIs and implementation. This patch unifies the behaviour and makes it store and operate exclusively on smack_known struct pointers when managing labels. Signed-off-by: Lukasz Pawelczyk Conflicts: security/smack/smack_access.c security/smack/smack_lsm.c