kernel/security/security.c, branch linux-5.10.y

ima: Avoid blocking in RCU read-side critical section

2024-07-18T11:05:44Z

commit 9a95c5bfbf02a0a7f5983280fe284a0ff0836c34 upstream. A panic happens in ima_match_policy: BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 PGD 42f873067 P4D 0 Oops: 0000 [#1] SMP NOPTI CPU: 5 PID: 1286325 Comm: kubeletmonit.sh Kdump: loaded Tainted: P Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015 RIP: 0010:ima_match_policy+0x84/0x450 Code: 49 89 fc 41 89 cf 31 ed 89 44 24 14 eb 1c 44 39 7b 18 74 26 41 83 ff 05 74 20 48 8b 1b 48 3b 1d f2 b9 f4 00 0f 84 9c 01 00 00 <44> 85 73 10 74 ea 44 8b 6b 14 41 f6 c5 01 75 d4 41 f6 c5 02 74 0f RSP: 0018:ff71570009e07a80 EFLAGS: 00010207 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000200 RDX: ffffffffad8dc7c0 RSI: 0000000024924925 RDI: ff3e27850dea2000 RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffffabfce739 R10: ff3e27810cc42400 R11: 0000000000000000 R12: ff3e2781825ef970 R13: 00000000ff3e2785 R14: 000000000000000c R15: 0000000000000001 FS: 00007f5195b51740(0000) GS:ff3e278b12d40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000010 CR3: 0000000626d24002 CR4: 0000000000361ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ima_get_action+0x22/0x30 process_measurement+0xb0/0x830 ? page_add_file_rmap+0x15/0x170 ? alloc_set_pte+0x269/0x4c0 ? prep_new_page+0x81/0x140 ? simple_xattr_get+0x75/0xa0 ? selinux_file_open+0x9d/0xf0 ima_file_check+0x64/0x90 path_openat+0x571/0x1720 do_filp_open+0x9b/0x110 ? page_counter_try_charge+0x57/0xc0 ? files_cgroup_alloc_fd+0x38/0x60 ? __alloc_fd+0xd4/0x250 ? do_sys_open+0x1bd/0x250 do_sys_open+0x1bd/0x250 do_syscall_64+0x5d/0x1d0 entry_SYSCALL_64_after_hwframe+0x65/0xca Commit c7423dbdbc9e ("ima: Handle -ESTALE returned by ima_filter_rule_match()") introduced call to ima_lsm_copy_rule within a RCU read-side critical section which contains kmalloc with GFP_KERNEL. This implies a possible sleep and violates limitations of RCU read-side critical sections on non-PREEMPT systems. Sleeping within RCU read-side critical section might cause synchronize_rcu() returning early and break RCU protection, allowing a UAF to happen. The root cause of this issue could be described as follows: | Thread A | Thread B | | |ima_match_policy | | | rcu_read_lock | |ima_lsm_update_rule | | | synchronize_rcu | | | | kmalloc(GFP_KERNEL)| | | sleep | ==> synchronize_rcu returns early | kfree(entry) | | | | entry = entry->next| ==> UAF happens and entry now becomes NULL (or could be anything). | | entry->action | ==> Accessing entry might cause panic. To fix this issue, we are converting all kmalloc that is called within RCU read-side critical section to use GFP_ATOMIC. Fixes: c7423dbdbc9e ("ima: Handle -ESTALE returned by ima_filter_rule_match()") Cc: stable@vger.kernel.org Signed-off-by: GUO Zihua Acked-by: John Johansen Reviewed-by: Mimi Zohar Reviewed-by: Casey Schaufler [PM: fixed missing comment, long lines, !CONFIG_IMA_LSM_RULES case] Signed-off-by: Paul Moore Signed-off-by: Roberto Sassu Signed-off-by: Greg Kroah-Hartman

lsm: fix default return value of the socket_getpeersec_*() hooks

2024-03-15T14:48:20Z

[ Upstream commit 5a287d3d2b9de2b3e747132c615599907ba5c3c1 ] For these hooks the true "neutral" value is -EOPNOTSUPP, which is currently what is returned when no LSM provides this hook and what LSMs return when there is no security context set on the socket. Correct the value in and adjust the dispatch functions in security/security.c to avoid issues when the BPF LSM is enabled. Cc: stable@vger.kernel.org Fixes: 98e828a0650f ("security: Refactor declaration of LSM hooks") Signed-off-by: Ondrej Mosnacek [PM: subject line tweak] Signed-off-by: Paul Moore Signed-off-by: Sasha Levin

lsm: make security_socket_getpeersec_stream() sockptr_t safe

2024-03-15T14:48:20Z

[ Upstream commit b10b9c342f7571f287fd422be5d5c0beb26ba974 ] Commit 4ff09db1b79b ("bpf: net: Change sk_getsockopt() to take the sockptr_t argument") made it possible to call sk_getsockopt() with both user and kernel address space buffers through the use of the sockptr_t type. Unfortunately at the time of conversion the security_socket_getpeersec_stream() LSM hook was written to only accept userspace buffers, and in a desire to avoid having to change the LSM hook the commit author simply passed the sockptr_t's userspace buffer pointer. Since the only sk_getsockopt() callers at the time of conversion which used kernel sockptr_t buffers did not allow SO_PEERSEC, and hence the security_socket_getpeersec_stream() hook, this was acceptable but also very fragile as future changes presented the possibility of silently passing kernel space pointers to the LSM hook. There are several ways to protect against this, including careful code review of future commits, but since relying on code review to catch bugs is a recipe for disaster and the upstream eBPF maintainer is "strongly against defensive programming", this patch updates the LSM hook, and all of the implementations to support sockptr_t and safely handle both user and kernel space buffers. Acked-by: Casey Schaufler Acked-by: John Johansen Signed-off-by: Paul Moore Stable-dep-of: 5a287d3d2b9d ("lsm: fix default return value of the socket_getpeersec_*() hooks") Signed-off-by: Sasha Levin

lsm: fix the logic in security_inode_getsecctx()

2024-02-23T07:42:26Z

commit 99b817c173cd213671daecd25ca27f56b0c7c4ec upstream. The inode_getsecctx LSM hook has previously been corrected to have -EOPNOTSUPP instead of 0 as the default return value to fix BPF LSM behavior. However, the call_int_hook()-generated loop in security_inode_getsecctx() was left treating 0 as the neutral value, so after an LSM returns 0, the loop continues to try other LSMs, and if one of them returns a non-zero value, the function immediately returns with said value. So in a situation where SELinux and the BPF LSMs registered this hook, -EOPNOTSUPP would be incorrectly returned whenever SELinux returned 0. Fix this by open-coding the call_int_hook() loop and making it use the correct LSM_RET_DEFAULT() value as the neutral one, similar to what other hooks do. Cc: stable@vger.kernel.org Reported-by: Stephen Smalley Link: https://lore.kernel.org/selinux/CAEjxPJ4ev-pasUwGx48fDhnmjBnq_Wh90jYPwRQRAqXxmOKD4Q@mail.gmail.com/ Link: https://bugzilla.redhat.com/show_bug.cgi?id=2257983 Fixes: b36995b8609a ("lsm: fix default return value for inode_getsecctx") Signed-off-by: Ondrej Mosnacek Reviewed-by: Casey Schaufler [PM: subject line tweak] Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman

lsm: new security_file_ioctl_compat() hook

2024-02-23T07:41:53Z

commit f1bb47a31dff6d4b34fb14e99850860ee74bb003 upstream. Some ioctl commands do not require ioctl permission, but are routed to other permissions such as FILE_GETATTR or FILE_SETATTR. This routing is done by comparing the ioctl cmd to a set of 64-bit flags (FS_IOC_*). However, if a 32-bit process is running on a 64-bit kernel, it emits 32-bit flags (FS_IOC32_*) for certain ioctl operations. These flags are being checked erroneously, which leads to these ioctl operations being routed to the ioctl permission, rather than the correct file permissions. This was also noted in a RED-PEN finding from a while back - "/* RED-PEN how should LSM module know it's handling 32bit? */". This patch introduces a new hook, security_file_ioctl_compat(), that is called from the compat ioctl syscall. All current LSMs have been changed to support this hook. Reviewing the three places where we are currently using security_file_ioctl(), it appears that only SELinux needs a dedicated compat change; TOMOYO and SMACK appear to be functional without any change. Cc: stable@vger.kernel.org Fixes: 0b24dcb7f2f7 ("Revert "selinux: simplify ioctl checking"") Signed-off-by: Alfred Piccioni Reviewed-by: Stephen Smalley [PM: subject tweak, line length fixes, and alignment corrections] Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman

ima: Align ima_file_mmap() parameters with mmap_file LSM hook

2023-03-11T15:40:00Z

commit 4971c268b85e1c7a734a61622fc0813c86e2362e upstream. Commit 98de59bfe4b2f ("take calculation of final prot in security_mmap_file() into a helper") moved the code to update prot, to be the actual protections applied to the kernel, to a new helper called mmap_prot(). However, while without the helper ima_file_mmap() was getting the updated prot, with the helper ima_file_mmap() gets the original prot, which contains the protections requested by the application. A possible consequence of this change is that, if an application calls mmap() with only PROT_READ, and the kernel applies PROT_EXEC in addition, that application would have access to executable memory without having this event recorded in the IMA measurement list. This situation would occur for example if the application, before mmap(), calls the personality() system call with READ_IMPLIES_EXEC as the first argument. Align ima_file_mmap() parameters with those of the mmap_file LSM hook, so that IMA can receive both the requested prot and the final prot. Since the requested protections are stored in a new variable, and the final protections are stored in the existing variable, this effectively restores the original behavior of the MMAP_CHECK hook. Cc: stable@vger.kernel.org Fixes: 98de59bfe4b2 ("take calculation of final prot in security_mmap_file() into a helper") Signed-off-by: Roberto Sassu Reviewed-by: Stefan Berger Signed-off-by: Mimi Zohar Signed-off-by: Greg Kroah-Hartman

lsm,selinux: pass flowi_common instead of flowi to the LSM hooks

2022-06-09T08:21:09Z

[ Upstream commit 3df98d79215ace13d1e91ddfc5a67a0f5acbd83f ] As pointed out by Herbert in a recent related patch, the LSM hooks do not have the necessary address family information to use the flowi struct safely. As none of the LSMs currently use any of the protocol specific flowi information, replace the flowi pointers with pointers to the address family independent flowi_common struct. Reported-by: Herbert Xu Acked-by: James Morris Signed-off-by: Paul Moore Signed-off-by: Sasha Levin

lockdown: also lock down previous kgdb use

2022-05-30T07:33:22Z

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

LSM: general protection fault in legacy_parse_param

2022-04-08T12:40:30Z

[ Upstream commit ecff30575b5ad0eda149aadad247b7f75411fd47 ] 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 Signed-off-by: Sasha Levin

binder: use cred instead of task for selinux checks

2021-11-18T13:03:36Z

commit 52f88693378a58094c538662ba652aff0253c4fe upstream. Since binder was integrated with selinux, it has passed 'struct task_struct' associated with the binder_proc to represent the source and target of transactions. The conversion of task to SID was then done in the hook implementations. It turns out that there are race conditions which can result in an incorrect security context being used. Fix by using the 'struct cred' saved during binder_open and pass it to the selinux subsystem. Cc: stable@vger.kernel.org # 5.14 (need backport for earlier stables) Fixes: 79af73079d75 ("Add security hooks to binder and implement the hooks for SELinux.") Suggested-by: Jann Horn Signed-off-by: Todd Kjos Acked-by: Casey Schaufler Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman