user/sven/linux.git/security/security.c, branch v5.18.3

lockdown: also lock down previous kgdb use

2022-05-30T07:24:03Z

commit eadb2f47a3ced5c64b23b90fd2a3463f63726066 upstream. KGDB and KDB allow read and write access to kernel memory, and thus should be restricted during lockdown. An attacker with access to a serial port (for example, via a hypervisor console, which some cloud vendors provide over the network) could trigger the debugger so it is important that the debugger respect the lockdown mode when/if it is triggered. Fix this by integrating lockdown into kdb's existing permissions mechanism. Unfortunately kgdb does not have any permissions mechanism (although it certainly could be added later) so, for now, kgdb is simply and brutally disabled by immediately exiting the gdb stub without taking any action. For lockdowns established early in the boot (e.g. the normal case) then this should be fine but on systems where kgdb has set breakpoints before the lockdown is enacted than "bad things" will happen. CVE: CVE-2022-21499 Co-developed-by: Stephen Brennan Signed-off-by: Stephen Brennan Reviewed-by: Douglas Anderson Signed-off-by: Daniel Thompson Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

Merge tag 'selinux-pr-20220321' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

2022-03-22T03:47:54Z

Pull selinux updates from Paul Moore: "We've got a number of SELinux patches queued up, the highlights are: - Fixup the security_fs_context_parse_param() LSM hook so it executes all of the LSM hook implementations unless a serious error occurs. We also correct the SELinux hook implementation so that it returns zero on success. - In addition to a few SELinux mount option parsing fixes, we simplified the parsing by moving it earlier in the process. The logic was that it was unlikely an admin/user would use the new mount API and not have the policy loaded before passing the SELinux options. - Properly fixed the LSM/SELinux/SCTP hooks with the addition of the security_sctp_assoc_established() hook. This work was done in conjunction with the netdev folks and should complete the move of the SCTP labeling from the endpoints to the associations. - Fixed a variety of sparse warnings caused by changes in the "__rcu" markings of some core kernel structures. - Ensure we access the superblock's LSM security blob using the stacking-safe accessors. - Added the ability for the kernel to always allow FIOCLEX and FIONCLEX if the "ioctl_skip_cloexec" policy capability is specified. - Various constifications improvements, type casting improvements, additional return value checks, and dead code/parameter removal. - Documentation fixes" * tag 'selinux-pr-20220321' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux: (23 commits) selinux: shorten the policy capability enum names docs: fix 'make htmldocs' warning in SCTP.rst selinux: allow FIOCLEX and FIONCLEX with policy capability selinux: use correct type for context length selinux: drop return statement at end of void functions security: implement sctp_assoc_established hook in selinux security: add sctp_assoc_established hook selinux: parse contexts for mount options early selinux: various sparse fixes selinux: try to use preparsed sid before calling parse_sid() selinux: Fix selinux_sb_mnt_opts_compat() LSM: general protection fault in legacy_parse_param selinux: fix a type cast problem in cred_init_security() selinux: drop unused macro selinux: simplify cred_init_security selinux: do not discard const qualifier in cast selinux: drop unused parameter of avtab_insert_node selinux: drop cast to same type selinux: enclose macro arguments in parenthesis selinux: declare name parameter of hash_eval const ...

security: add sctp_assoc_established hook

2022-02-15T20:03:38Z

security_sctp_assoc_established() is added to replace security_inet_conn_established() called in sctp_sf_do_5_1E_ca(), so that asoc can be accessed in security subsystem and save the peer secid to asoc->peer_secid. Fixes: 72e89f50084c ("security: Add support for SCTP security hooks") Reported-by: Prashanth Prahlad Based-on-patch-by: Xin Long Reviewed-by: Xin Long Tested-by: Richard Haines Signed-off-by: Ondrej Mosnacek Signed-off-by: Paul Moore

Merge tag 'fixes-v5.17-lsm-ceph-null' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

2022-01-29T06:52:27Z

Pull security sybsystem fix from James Morris: "Fix NULL pointer crash in LSM via Ceph, from Vivek Goyal" * tag 'fixes-v5.17-lsm-ceph-null' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: security, lsm: dentry_init_security() Handle multi LSM registration

security, lsm: dentry_init_security() Handle multi LSM registration

2022-01-28T18:53:26Z

A ceph user has reported that ceph is crashing with kernel NULL pointer dereference. Following is the backtrace. /proc/version: Linux version 5.16.2-arch1-1 (linux@archlinux) (gcc (GCC) 11.1.0, GNU ld (GNU Binutils) 2.36.1) #1 SMP PREEMPT Thu, 20 Jan 2022 16:18:29 +0000 distro / arch: Arch Linux / x86_64 SELinux is not enabled ceph cluster version: 16.2.7 (dd0603118f56ab514f133c8d2e3adfc983942503) relevant dmesg output: [ 30.947129] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 30.947206] #PF: supervisor read access in kernel mode [ 30.947258] #PF: error_code(0x0000) - not-present page [ 30.947310] PGD 0 P4D 0 [ 30.947342] Oops: 0000 [#1] PREEMPT SMP PTI [ 30.947388] CPU: 5 PID: 778 Comm: touch Not tainted 5.16.2-arch1-1 #1 86fbf2c313cc37a553d65deb81d98e9dcc2a3659 [ 30.947486] Hardware name: Gigabyte Technology Co., Ltd. B365M DS3H/B365M DS3H, BIOS F5 08/13/2019 [ 30.947569] RIP: 0010:strlen+0x0/0x20 [ 30.947616] Code: b6 07 38 d0 74 16 48 83 c7 01 84 c0 74 05 48 39 f7 75 ec 31 c0 31 d2 89 d6 89 d7 c3 48 89 f8 31 d2 89 d6 89 d7 c3 0 f 1f 40 00 <80> 3f 00 74 12 48 89 f8 48 83 c0 01 80 38 00 75 f7 48 29 f8 31 ff [ 30.947782] RSP: 0018:ffffa4ed80ffbbb8 EFLAGS: 00010246 [ 30.947836] RAX: 0000000000000000 RBX: ffffa4ed80ffbc60 RCX: 0000000000000000 [ 30.947904] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 30.947971] RBP: ffff94b0d15c0ae0 R08: 0000000000000000 R09: 0000000000000000 [ 30.948040] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 30.948106] R13: 0000000000000001 R14: ffffa4ed80ffbc60 R15: 0000000000000000 [ 30.948174] FS: 00007fc7520f0740(0000) GS:ffff94b7ced40000(0000) knlGS:0000000000000000 [ 30.948252] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 30.948308] CR2: 0000000000000000 CR3: 0000000104a40001 CR4: 00000000003706e0 [ 30.948376] Call Trace: [ 30.948404] [ 30.948431] ceph_security_init_secctx+0x7b/0x240 [ceph 49f9c4b9bf5be8760f19f1747e26da33920bce4b] [ 30.948582] ceph_atomic_open+0x51e/0x8a0 [ceph 49f9c4b9bf5be8760f19f1747e26da33920bce4b] [ 30.948708] ? get_cached_acl+0x4d/0xa0 [ 30.948759] path_openat+0x60d/0x1030 [ 30.948809] do_filp_open+0xa5/0x150 [ 30.948859] do_sys_openat2+0xc4/0x190 [ 30.948904] __x64_sys_openat+0x53/0xa0 [ 30.948948] do_syscall_64+0x5c/0x90 [ 30.948989] ? exc_page_fault+0x72/0x180 [ 30.949034] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 30.949091] RIP: 0033:0x7fc7521e25bb [ 30.950849] Code: 25 00 00 41 00 3d 00 00 41 00 74 4b 64 8b 04 25 18 00 00 00 85 c0 75 67 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 0 0 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 91 00 00 00 48 8b 54 24 28 64 48 2b 14 25 Core of the problem is that ceph checks for return code from security_dentry_init_security() and if return code is 0, it assumes everything is fine and continues to call strlen(name), which crashes. Typically SELinux LSM returns 0 and sets name to "security.selinux" and it is not a problem. Or if selinux is not compiled in or disabled, it returns -EOPNOTSUP and ceph deals with it. But somehow in this configuration, 0 is being returned and "name" is not being initialized and that's creating the problem. Our suspicion is that BPF LSM is registering a hook for dentry_init_security() and returns hook default of 0. LSM_HOOK(int, 0, dentry_init_security, struct dentry *dentry,...) I have not been able to reproduce it just by doing CONFIG_BPF_LSM=y. Stephen has tested the patch though and confirms it solves the problem for him. dentry_init_security() is written in such a way that it expects only one LSM to register the hook. Atleast that's the expectation with current code. If another LSM returns a hook and returns default, it will simply return 0 as of now and that will break ceph. Hence, suggestion is that change semantics of this hook a bit. If there are no LSMs or no LSM is taking ownership and initializing security context, then return -EOPNOTSUP. Also allow at max one LSM to initialize security context. This hook can't deal with multiple LSMs trying to init security context. This patch implements this new behavior. Reported-by: Stephen Muth Tested-by: Stephen Muth Suggested-by: Casey Schaufler Acked-by: Casey Schaufler Reviewed-by: Serge Hallyn Cc: Jeff Layton Cc: Christian Brauner Cc: Paul Moore Cc: # 5.16.0 Signed-off-by: Vivek Goyal Reviewed-by: Jeff Layton Acked-by: Paul Moore Acked-by: Christian Brauner Signed-off-by: James Morris

LSM: general protection fault in legacy_parse_param

2022-01-28T01:43:02Z

The usual LSM hook "bail on fail" scheme doesn't work for cases where a security module may return an error code indicating that it does not recognize an input. In this particular case Smack sees a mount option that it recognizes, and returns 0. A call to a BPF hook follows, which returns -ENOPARAM, which confuses the caller because Smack has processed its data. The SELinux hook incorrectly returns 1 on success. There was a time when this was correct, however the current expectation is that it return 0 on success. This is repaired. Reported-by: syzbot+d1e3b1d92d25abf97943@syzkaller.appspotmail.com Signed-off-by: Casey Schaufler Acked-by: James Morris Signed-off-by: Paul Moore

security,selinux: remove security_add_mnt_opt()

2021-12-06T18:46:24Z

Its last user has been removed in commit f2aedb713c28 ("NFS: Add fs_context support."). Signed-off-by: Ondrej Mosnacek Reviewed-by: Casey Schaufler Signed-off-by: Paul Moore

lsm: security_task_getsecid_subj() -> security_current_getsecid_subj()

2021-11-22T22:52:47Z

The security_task_getsecid_subj() LSM hook invites misuse by allowing callers to specify a task even though the hook is only safe when the current task is referenced. Fix this by removing the task_struct argument to the hook, requiring LSM implementations to use the current task. While we are changing the hook declaration we also rename the function to security_current_getsecid_subj() in an effort to reinforce that the hook captures the subjective credentials of the current task and not an arbitrary task on the system. Reviewed-by: Serge Hallyn Reviewed-by: Casey Schaufler Signed-off-by: Paul Moore

net,lsm,selinux: revert the security_sctp_assoc_established() hook

2021-11-12T17:07:02Z

This patch reverts two prior patches, e7310c94024c ("security: implement sctp_assoc_established hook in selinux") and 7c2ef0240e6a ("security: add sctp_assoc_established hook"), which create the security_sctp_assoc_established() LSM hook and provide a SELinux implementation. Unfortunately these two patches were merged without proper review (the Reviewed-by and Tested-by tags from Richard Haines were for previous revisions of these patches that were significantly different) and there are outstanding objections from the SELinux maintainers regarding these patches. Work is currently ongoing to correct the problems identified in the reverted patches, as well as others that have come up during review, but it is unclear at this point in time when that work will be ready for inclusion in the mainline kernel. In the interest of not keeping objectionable code in the kernel for multiple weeks, and potentially a kernel release, we are reverting the two problematic patches. Signed-off-by: Paul Moore

security: add sctp_assoc_established hook

2021-11-03T11:09:20Z

security_sctp_assoc_established() is added to replace security_inet_conn_established() called in sctp_sf_do_5_1E_ca(), so that asoc can be accessed in security subsystem and save the peer secid to asoc->peer_secid. v1->v2: - fix the return value of security_sctp_assoc_established() in security.h, found by kernel test robot and Ondrej. Fixes: 72e89f50084c ("security: Add support for SCTP security hooks") Reported-by: Prashanth Prahlad Reviewed-by: Richard Haines Tested-by: Richard Haines Signed-off-by: Xin Long Signed-off-by: David S. Miller