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2019-10-31efi/efi_test: Lock down /dev/efi_test and require CAP_SYS_ADMINJavier Martinez Canillas
The driver exposes EFI runtime services to user-space through an IOCTL interface, calling the EFI services function pointers directly without using the efivar API. Disallow access to the /dev/efi_test character device when the kernel is locked down to prevent arbitrary user-space to call EFI runtime services. Also require CAP_SYS_ADMIN to open the chardev to prevent unprivileged users to call the EFI runtime services, instead of just relying on the chardev file mode bits for this. The main user of this driver is the fwts [0] tool that already checks if the effective user ID is 0 and fails otherwise. So this change shouldn't cause any regression to this tool. [0]: https://wiki.ubuntu.com/FirmwareTestSuite/Reference/uefivarinfo Signed-off-by: Javier Martinez Canillas <javierm@redhat.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Laszlo Ersek <lersek@redhat.com> Acked-by: Matthew Garrett <mjg59@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Link: https://lkml.kernel.org/r/20191029173755.27149-7-ardb@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-08Merge tag 'selinux-pr-20191007' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux Pull selinuxfix from Paul Moore: "One patch to ensure we don't copy bad memory up into userspace" * tag 'selinux-pr-20191007' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux: selinux: fix context string corruption in convert_context()
2019-10-05integrity: remove pointless subdir-$(CONFIG_...)Masahiro Yamada
The ima/ and evm/ sub-directories contain built-in objects, so obj-$(CONFIG_...) is the correct way to descend into them. subdir-$(CONFIG_...) is redundant. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-10-05integrity: remove unneeded, broken attempt to add -fshort-wcharMasahiro Yamada
I guess commit 15ea0e1e3e18 ("efi: Import certificates from UEFI Secure Boot") attempted to add -fshort-wchar for building load_uefi.o, but it has never worked as intended. load_uefi.o is created in the platform_certs/ sub-directory. If you really want to add -fshort-wchar, the correct code is: $(obj)/platform_certs/load_uefi.o: KBUILD_CFLAGS += -fshort-wchar But, you do not need to fix it. Commit 8c97023cf051 ("Kbuild: use -fshort-wchar globally") had already added -fshort-wchar globally. This code was unneeded in the first place. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-10-03selinux: fix context string corruption in convert_context()Ondrej Mosnacek
string_to_context_struct() may garble the context string, so we need to copy back the contents again from the old context struct to avoid storing the corrupted context. Since string_to_context_struct() tokenizes (and therefore truncates) the context string and we are later potentially copying it with kstrdup(), this may eventually cause pieces of uninitialized kernel memory to be disclosed to userspace (when copying to userspace based on the stored length and not the null character). How to reproduce on Fedora and similar: # dnf install -y memcached # systemctl start memcached # semodule -d memcached # load_policy # load_policy # systemctl stop memcached # ausearch -m AVC type=AVC msg=audit(1570090572.648:313): avc: denied { signal } for pid=1 comm="systemd" scontext=system_u:system_r:init_t:s0 tcontext=system_u:object_r:unlabeled_t:s0 tclass=process permissive=0 trawcon=73797374656D5F75007400000000000070BE6E847296FFFF726F6D000096FFFF76 Cc: stable@vger.kernel.org Reported-by: Milos Malik <mmalik@redhat.com> Fixes: ee1a84fdfeed ("selinux: overhaul sidtab to fix bug and improve performance") Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Acked-by: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-09-28Merge branch 'next-lockdown' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security Pull kernel lockdown mode from James Morris: "This is the latest iteration of the kernel lockdown patchset, from Matthew Garrett, David Howells and others. From the original description: This patchset introduces an optional kernel lockdown feature, intended to strengthen the boundary between UID 0 and the kernel. When enabled, various pieces of kernel functionality are restricted. Applications that rely on low-level access to either hardware or the kernel may cease working as a result - therefore this should not be enabled without appropriate evaluation beforehand. The majority of mainstream distributions have been carrying variants of this patchset for many years now, so there's value in providing a doesn't meet every distribution requirement, but gets us much closer to not requiring external patches. There are two major changes since this was last proposed for mainline: - Separating lockdown from EFI secure boot. Background discussion is covered here: https://lwn.net/Articles/751061/ - Implementation as an LSM, with a default stackable lockdown LSM module. This allows the lockdown feature to be policy-driven, rather than encoding an implicit policy within the mechanism. The new locked_down LSM hook is provided to allow LSMs to make a policy decision around whether kernel functionality that would allow tampering with or examining the runtime state of the kernel should be permitted. The included lockdown LSM provides an implementation with a simple policy intended for general purpose use. This policy provides a coarse level of granularity, controllable via the kernel command line: lockdown={integrity|confidentiality} Enable the kernel lockdown feature. If set to integrity, kernel features that allow userland to modify the running kernel are disabled. If set to confidentiality, kernel features that allow userland to extract confidential information from the kernel are also disabled. This may also be controlled via /sys/kernel/security/lockdown and overriden by kernel configuration. New or existing LSMs may implement finer-grained controls of the lockdown features. Refer to the lockdown_reason documentation in include/linux/security.h for details. The lockdown feature has had signficant design feedback and review across many subsystems. This code has been in linux-next for some weeks, with a few fixes applied along the way. Stephen Rothwell noted that commit 9d1f8be5cf42 ("bpf: Restrict bpf when kernel lockdown is in confidentiality mode") is missing a Signed-off-by from its author. Matthew responded that he is providing this under category (c) of the DCO" * 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (31 commits) kexec: Fix file verification on S390 security: constify some arrays in lockdown LSM lockdown: Print current->comm in restriction messages efi: Restrict efivar_ssdt_load when the kernel is locked down tracefs: Restrict tracefs when the kernel is locked down debugfs: Restrict debugfs when the kernel is locked down kexec: Allow kexec_file() with appropriate IMA policy when locked down lockdown: Lock down perf when in confidentiality mode bpf: Restrict bpf when kernel lockdown is in confidentiality mode lockdown: Lock down tracing and perf kprobes when in confidentiality mode lockdown: Lock down /proc/kcore x86/mmiotrace: Lock down the testmmiotrace module lockdown: Lock down module params that specify hardware parameters (eg. ioport) lockdown: Lock down TIOCSSERIAL lockdown: Prohibit PCMCIA CIS storage when the kernel is locked down acpi: Disable ACPI table override if the kernel is locked down acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down ACPI: Limit access to custom_method when the kernel is locked down x86/msr: Restrict MSR access when the kernel is locked down x86: Lock down IO port access when the kernel is locked down ...
2019-09-27Merge branch 'next-integrity' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity Pull integrity updates from Mimi Zohar: "The major feature in this time is IMA support for measuring and appraising appended file signatures. In addition are a couple of bug fixes and code cleanup to use struct_size(). In addition to the PE/COFF and IMA xattr signatures, the kexec kernel image may be signed with an appended signature, using the same scripts/sign-file tool that is used to sign kernel modules. Similarly, the initramfs may contain an appended signature. This contained a lot of refactoring of the existing appended signature verification code, so that IMA could retain the existing framework of calculating the file hash once, storing it in the IMA measurement list and extending the TPM, verifying the file's integrity based on a file hash or signature (eg. xattrs), and adding an audit record containing the file hash, all based on policy. (The IMA support for appended signatures patch set was posted and reviewed 11 times.) The support for appended signature paves the way for adding other signature verification methods, such as fs-verity, based on a single system-wide policy. The file hash used for verifying the signature and the signature, itself, can be included in the IMA measurement list" * 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity: ima: ima_api: Use struct_size() in kzalloc() ima: use struct_size() in kzalloc() sefltest/ima: support appended signatures (modsig) ima: Fix use after free in ima_read_modsig() MODSIGN: make new include file self contained ima: fix freeing ongoing ahash_request ima: always return negative code for error ima: Store the measurement again when appraising a modsig ima: Define ima-modsig template ima: Collect modsig ima: Implement support for module-style appended signatures ima: Factor xattr_verify() out of ima_appraise_measurement() ima: Add modsig appraise_type option for module-style appended signatures integrity: Select CONFIG_KEYS instead of depending on it PKCS#7: Introduce pkcs7_get_digest() PKCS#7: Refactor verify_pkcs7_signature() MODSIGN: Export module signature definitions ima: initialize the "template" field with the default template
2019-09-25KEYS: trusted: correctly initialize digests and fix locking issueRoberto Sassu
Commit 0b6cf6b97b7e ("tpm: pass an array of tpm_extend_digest structures to tpm_pcr_extend()") modifies tpm_pcr_extend() to accept a digest for each PCR bank. After modification, tpm_pcr_extend() expects that digests are passed in the same order as the algorithms set in chip->allocated_banks. This patch fixes two issues introduced in the last iterations of the patch set: missing initialization of the TPM algorithm ID in the tpm_digest structures passed to tpm_pcr_extend() by the trusted key module, and unreleased locks in the TPM driver due to returning from tpm_pcr_extend() without calling tpm_put_ops(). Cc: stable@vger.kernel.org Fixes: 0b6cf6b97b7e ("tpm: pass an array of tpm_extend_digest structures to tpm_pcr_extend()") Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> Suggested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
2019-09-23Merge tag 'smack-for-5.4-rc1' of git://github.com/cschaufler/smack-nextLinus Torvalds
Pull smack updates from Casey Schaufler: "Four patches for v5.4. Nothing is major. All but one are in response to mechanically detected potential issues. The remaining patch cleans up kernel-doc notations" * tag 'smack-for-5.4-rc1' of git://github.com/cschaufler/smack-next: smack: use GFP_NOFS while holding inode_smack::smk_lock security: smack: Fix possible null-pointer dereferences in smack_socket_sock_rcv_skb() smack: fix some kernel-doc notations Smack: Don't ignore other bprm->unsafe flags if LSM_UNSAFE_PTRACE is set
2019-09-23Merge tag 'safesetid-bugfix-5.4' of git://github.com/micah-morton/linuxLinus Torvalds
Pull SafeSetID fix from Micah Morton: "Jann Horn sent some patches to fix some bugs in SafeSetID for 5.3. After he had done his testing there were a couple small code tweaks that went in and caused this bug. From what I can see SafeSetID is broken in 5.3 and crashes the kernel every time during initialization if you try to use it. I came across this bug when backporting Jann's changes for 5.3 to older kernels (4.14 and 4.19). I've tested on a Chrome OS device with those kernels and verified that this change fixes things. It doesn't seem super useful to have this bake in linux-next, since it is completely broken in 5.3 and nobody noticed" * tag 'safesetid-bugfix-5.4' of git://github.com/micah-morton/linux: LSM: SafeSetID: Stop releasing uninitialized ruleset
2019-09-23Merge tag 'selinux-pr-20190917' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux Pull selinux updates from Paul Moore: - Add LSM hooks, and SELinux access control hooks, for dnotify, fanotify, and inotify watches. This has been discussed with both the LSM and fs/notify folks and everybody is good with these new hooks. - The LSM stacking changes missed a few calls to current_security() in the SELinux code; we fix those and remove current_security() for good. - Improve our network object labeling cache so that we always return the object's label, even when under memory pressure. Previously we would return an error if we couldn't allocate a new cache entry, now we always return the label even if we can't create a new cache entry for it. - Convert the sidtab atomic_t counter to a normal u32 with READ/WRITE_ONCE() and memory barrier protection. - A few patches to policydb.c to clean things up (remove forward declarations, long lines, bad variable names, etc) * tag 'selinux-pr-20190917' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux: lsm: remove current_security() selinux: fix residual uses of current_security() for the SELinux blob selinux: avoid atomic_t usage in sidtab fanotify, inotify, dnotify, security: add security hook for fs notifications selinux: always return a secid from the network caches if we find one selinux: policydb - rename type_val_to_struct_array selinux: policydb - fix some checkpatch.pl warnings selinux: shuffle around policydb.c to get rid of forward declarations
2019-09-17LSM: SafeSetID: Stop releasing uninitialized rulesetMicah Morton
The first time a rule set is configured for SafeSetID, we shouldn't be trying to release the previously configured ruleset, since there isn't one. Currently, the pointer that would point to a previously configured ruleset is uninitialized on first rule set configuration, leading to a crash when we try to call release_ruleset with that pointer. Acked-by: Jann Horn <jannh@google.com> Signed-off-by: Micah Morton <mortonm@chromium.org>
2019-09-10security: constify some arrays in lockdown LSMMatthew Garrett
No reason for these not to be const. Signed-off-by: Matthew Garrett <mjg59@google.com> Suggested-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
2019-09-05keys: Fix missing null pointer check in request_key_auth_describe()Hillf Danton
If a request_key authentication token key gets revoked, there's a window in which request_key_auth_describe() can see it with a NULL payload - but it makes no check for this and something like the following oops may occur: BUG: Kernel NULL pointer dereference at 0x00000038 Faulting instruction address: 0xc0000000004ddf30 Oops: Kernel access of bad area, sig: 11 [#1] ... NIP [...] request_key_auth_describe+0x90/0xd0 LR [...] request_key_auth_describe+0x54/0xd0 Call Trace: [...] request_key_auth_describe+0x54/0xd0 (unreliable) [...] proc_keys_show+0x308/0x4c0 [...] seq_read+0x3d0/0x540 [...] proc_reg_read+0x90/0x110 [...] __vfs_read+0x3c/0x70 [...] vfs_read+0xb4/0x1b0 [...] ksys_read+0x7c/0x130 [...] system_call+0x5c/0x70 Fix this by checking for a NULL pointer when describing such a key. Also make the read routine check for a NULL pointer to be on the safe side. [DH: Modified to not take already-held rcu lock and modified to also check in the read routine] Fixes: 04c567d9313e ("[PATCH] Keys: Fix race between two instantiators of a key") Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com> Signed-off-by: Hillf Danton <hdanton@sina.com> Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-09-04selinux: fix residual uses of current_security() for the SELinux blobStephen Smalley
We need to use selinux_cred() to fetch the SELinux cred blob instead of directly using current->security or current_security(). There were a couple of lingering uses of current_security() in the SELinux code that were apparently missed during the earlier conversions. IIUC, this would only manifest as a bug if multiple security modules including SELinux are enabled and SELinux is not first in the lsm order. After this change, there appear to be no other users of current_security() in-tree; perhaps we should remove it altogether. Fixes: bbd3662a8348 ("Infrastructure management of the cred security blob") Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Reviewed-by: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-09-04smack: use GFP_NOFS while holding inode_smack::smk_lockEric Biggers
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 <ebiggers@google.com> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2019-09-04security: smack: Fix possible null-pointer dereferences in ↵Jia-Ju Bai
smack_socket_sock_rcv_skb() In smack_socket_sock_rcv_skb(), there is an if statement on line 3920 to check whether skb is NULL: if (skb && skb->secmark != 0) This check indicates skb can be NULL in some cases. But on lines 3931 and 3932, skb is used: ad.a.u.net->netif = skb->skb_iif; ipv6_skb_to_auditdata(skb, &ad.a, NULL); Thus, possible null-pointer dereferences may occur when skb is NULL. To fix these possible bugs, an if statement is added to check skb. These bugs are found by a static analysis tool STCheck written by us. Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2019-09-04smack: fix some kernel-doc notationsluanshi
Fix/add kernel-doc notation and fix typos in security/smack/. Signed-off-by: Liguang Zhang <zhangliguang@linux.alibaba.com> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2019-09-04Smack: Don't ignore other bprm->unsafe flags if LSM_UNSAFE_PTRACE is setJann Horn
There is a logic bug in the current smack_bprm_set_creds(): If LSM_UNSAFE_PTRACE is set, but the ptrace state is deemed to be acceptable (e.g. because the ptracer detached in the meantime), the other ->unsafe flags aren't checked. As far as I can tell, this means that something like the following could work (but I haven't tested it): - task A: create task B with fork() - task B: set NO_NEW_PRIVS - task B: install a seccomp filter that makes open() return 0 under some conditions - task B: replace fd 0 with a malicious library - task A: attach to task B with PTRACE_ATTACH - task B: execve() a file with an SMACK64EXEC extended attribute - task A: while task B is still in the middle of execve(), exit (which destroys the ptrace relationship) Make sure that if any flags other than LSM_UNSAFE_PTRACE are set in bprm->unsafe, we reject the execve(). Cc: stable@vger.kernel.org Fixes: 5663884caab1 ("Smack: unify all ptrace accesses in the smack") Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2019-08-30keys: ensure that ->match_free() is called in request_key_and_link()Eric Biggers
If check_cached_key() returns a non-NULL value, we still need to call key_type::match_free() to undo key_type::match_preparse(). Fixes: 7743c48e54ee ("keys: Cache result of request_key*() temporarily in task_struct") Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-29ima: ima_api: Use struct_size() in kzalloc()Gustavo A. R. Silva
One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory for some number of elements for that array. For example: struct ima_template_entry { ... struct ima_field_data template_data[0]; /* template related data */ }; instance = kzalloc(sizeof(struct ima_template_entry) + count * sizeof(struct ima_field_data), GFP_NOFS); Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper: instance = kzalloc(struct_size(instance, entry, count), GFP_NOFS); This code was detected with the help of Coccinelle. Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2019-08-29ima: use struct_size() in kzalloc()Gustavo A. R. Silva
One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory for some number of elements for that array. For example: struct foo { int stuff; struct boo entry[]; }; instance = kzalloc(sizeof(struct foo) + count * sizeof(struct boo), GFP_KERNEL); Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper: instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL); This code was detected with the help of Coccinelle. Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2019-08-28ima: Fix use after free in ima_read_modsig()Thiago Jung Bauermann
If we can't parse the PKCS7 in the appended modsig, we will free the modsig structure and then access one of its members to determine the error value. Fixes: 39b07096364a ("ima: Implement support for module-style appended signatures") Reported-by: kbuild test robot <lkp@intel.com> Reported-by: Julia Lawall <julia.lawall@lip6.fr> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com> Reviewed-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2019-08-27selinux: avoid atomic_t usage in sidtabOndrej Mosnacek
As noted in Documentation/atomic_t.txt, if we don't need the RMW atomic operations, we should only use READ_ONCE()/WRITE_ONCE() + smp_rmb()/smp_wmb() where necessary (or the combined variants smp_load_acquire()/smp_store_release()). This patch converts the sidtab code to use regular u32 for the counter and reverse lookup cache and use the appropriate operations instead of atomic_get()/atomic_set(). Note that when reading/updating the reverse lookup cache we don't need memory barriers as it doesn't need to be consistent or accurate. We can now also replace some atomic ops with regular loads (when under spinlock) and stores (for conversion target fields that are always accessed under the master table's spinlock). We can now also bump SIDTAB_MAX to U32_MAX as we can use the full u32 range again. Suggested-by: Jann Horn <jannh@google.com> Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Reviewed-by: Jann Horn <jannh@google.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-08-19lockdown: Print current->comm in restriction messagesMatthew Garrett
Print the content of current->comm in messages generated by lockdown to indicate a restriction that was hit. This makes it a bit easier to find out what caused the message. The message now patterned something like: Lockdown: <comm>: <what> is restricted; see man kernel_lockdown.7 Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19tracefs: Restrict tracefs when the kernel is locked downMatthew Garrett
Tracefs may release more information about the kernel than desirable, so restrict it when the kernel is locked down in confidentiality mode by preventing open(). (Fixed by Ben Hutchings to avoid a null dereference in default_file_open()) Signed-off-by: Matthew Garrett <mjg59@google.com> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19debugfs: Restrict debugfs when the kernel is locked downDavid Howells
Disallow opening of debugfs files that might be used to muck around when the kernel is locked down as various drivers give raw access to hardware through debugfs. Given the effort of auditing all 2000 or so files and manually fixing each one as necessary, I've chosen to apply a heuristic instead. The following changes are made: (1) chmod and chown are disallowed on debugfs objects (though the root dir can be modified by mount and remount, but I'm not worried about that). (2) When the kernel is locked down, only files with the following criteria are permitted to be opened: - The file must have mode 00444 - The file must not have ioctl methods - The file must not have mmap (3) When the kernel is locked down, files may only be opened for reading. Normal device interaction should be done through configfs, sysfs or a miscdev, not debugfs. Note that this makes it unnecessary to specifically lock down show_dsts(), show_devs() and show_call() in the asus-wmi driver. I would actually prefer to lock down all files by default and have the the files unlocked by the creator. This is tricky to manage correctly, though, as there are 19 creation functions and ~1600 call sites (some of them in loops scanning tables). Signed-off-by: David Howells <dhowells@redhat.com> cc: Andy Shevchenko <andy.shevchenko@gmail.com> cc: acpi4asus-user@lists.sourceforge.net cc: platform-driver-x86@vger.kernel.org cc: Matthew Garrett <mjg59@srcf.ucam.org> cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg KH <greg@kroah.com> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Matthew Garrett <matthewgarrett@google.com> Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19kexec: Allow kexec_file() with appropriate IMA policy when locked downMatthew Garrett
Systems in lockdown mode should block the kexec of untrusted kernels. For x86 and ARM we can ensure that a kernel is trustworthy by validating a PE signature, but this isn't possible on other architectures. On those platforms we can use IMA digital signatures instead. Add a function to determine whether IMA has or will verify signatures for a given event type, and if so permit kexec_file() even if the kernel is otherwise locked down. This is restricted to cases where CONFIG_INTEGRITY_TRUSTED_KEYRING is set in order to prevent an attacker from loading additional keys at runtime. Signed-off-by: Matthew Garrett <mjg59@google.com> Acked-by: Mimi Zohar <zohar@linux.ibm.com> Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com> Cc: linux-integrity@vger.kernel.org Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19lockdown: Lock down perf when in confidentiality modeDavid Howells
Disallow the use of certain perf facilities that might allow userspace to access kernel data. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19bpf: Restrict bpf when kernel lockdown is in confidentiality modeDavid Howells
bpf_read() and bpf_read_str() could potentially be abused to (eg) allow private keys in kernel memory to be leaked. Disable them if the kernel has been locked down in confidentiality mode. Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> cc: netdev@vger.kernel.org cc: Chun-Yi Lee <jlee@suse.com> cc: Alexei Starovoitov <alexei.starovoitov@gmail.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19lockdown: Lock down tracing and perf kprobes when in confidentiality modeDavid Howells
Disallow the creation of perf and ftrace kprobes when the kernel is locked down in confidentiality mode by preventing their registration. This prevents kprobes from being used to access kernel memory to steal crypto data, but continues to allow the use of kprobes from signed modules. Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: davem@davemloft.net Cc: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19lockdown: Lock down /proc/kcoreDavid Howells
Disallow access to /proc/kcore when the kernel is locked down to prevent access to cryptographic data. This is limited to lockdown confidentiality mode and is still permitted in integrity mode. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19x86/mmiotrace: Lock down the testmmiotrace moduleDavid Howells
The testmmiotrace module shouldn't be permitted when the kernel is locked down as it can be used to arbitrarily read and write MMIO space. This is a runtime check rather than buildtime in order to allow configurations where the same kernel may be run in both locked down or permissive modes depending on local policy. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: David Howells <dhowells@redhat.com Signed-off-by: Matthew Garrett <mjg59@google.com> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reviewed-by: Kees Cook <keescook@chromium.org> cc: Thomas Gleixner <tglx@linutronix.de> cc: Steven Rostedt <rostedt@goodmis.org> cc: Ingo Molnar <mingo@kernel.org> cc: "H. Peter Anvin" <hpa@zytor.com> cc: x86@kernel.org Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19lockdown: Lock down module params that specify hardware parameters (eg. ioport)David Howells
Provided an annotation for module parameters that specify hardware parameters (such as io ports, iomem addresses, irqs, dma channels, fixed dma buffers and other types). Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Jessica Yu <jeyu@kernel.org> Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19lockdown: Lock down TIOCSSERIALDavid Howells
Lock down TIOCSSERIAL as that can be used to change the ioport and irq settings on a serial port. This only appears to be an issue for the serial drivers that use the core serial code. All other drivers seem to either ignore attempts to change port/irq or give an error. Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> cc: Jiri Slaby <jslaby@suse.com> Cc: linux-serial@vger.kernel.org Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19lockdown: Prohibit PCMCIA CIS storage when the kernel is locked downDavid Howells
Prohibit replacement of the PCMCIA Card Information Structure when the kernel is locked down. Suggested-by: Dominik Brodowski <linux@dominikbrodowski.net> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19ACPI: Limit access to custom_method when the kernel is locked downMatthew Garrett
custom_method effectively allows arbitrary access to system memory, making it possible for an attacker to circumvent restrictions on module loading. Disable it if the kernel is locked down. Signed-off-by: Matthew Garrett <mjg59@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org> cc: linux-acpi@vger.kernel.org Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19x86/msr: Restrict MSR access when the kernel is locked downMatthew Garrett
Writing to MSRs should not be allowed if the kernel is locked down, since it could lead to execution of arbitrary code in kernel mode. Based on a patch by Kees Cook. Signed-off-by: Matthew Garrett <mjg59@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Kees Cook <keescook@chromium.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> cc: x86@kernel.org Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19x86: Lock down IO port access when the kernel is locked downMatthew Garrett
IO port access would permit users to gain access to PCI configuration registers, which in turn (on a lot of hardware) give access to MMIO register space. This would potentially permit root to trigger arbitrary DMA, so lock it down by default. This also implicitly locks down the KDADDIO, KDDELIO, KDENABIO and KDDISABIO console ioctls. Signed-off-by: Matthew Garrett <mjg59@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org> cc: x86@kernel.org Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19PCI: Lock down BAR access when the kernel is locked downMatthew Garrett
Any hardware that can potentially generate DMA has to be locked down in order to avoid it being possible for an attacker to modify kernel code, allowing them to circumvent disabled module loading or module signing. Default to paranoid - in future we can potentially relax this for sufficiently IOMMU-isolated devices. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> cc: linux-pci@vger.kernel.org Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19hibernate: Disable when the kernel is locked downJosh Boyer
There is currently no way to verify the resume image when returning from hibernate. This might compromise the signed modules trust model, so until we can work with signed hibernate images we disable it when the kernel is locked down. Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: rjw@rjwysocki.net Cc: pavel@ucw.cz cc: linux-pm@vger.kernel.org Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCEJiri Bohac
This is a preparatory patch for kexec_file_load() lockdown. A locked down kernel needs to prevent unsigned kernel images from being loaded with kexec_file_load(). Currently, the only way to force the signature verification is compiling with KEXEC_VERIFY_SIG. This prevents loading usigned images even when the kernel is not locked down at runtime. This patch splits KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE. Analogous to the MODULE_SIG and MODULE_SIG_FORCE for modules, KEXEC_SIG turns on the signature verification but allows unsigned images to be loaded. KEXEC_SIG_FORCE disallows images without a valid signature. Signed-off-by: Jiri Bohac <jbohac@suse.cz> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <mjg59@google.com> cc: kexec@lists.infradead.org Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19kexec_load: Disable at runtime if the kernel is locked downMatthew Garrett
The kexec_load() syscall permits the loading and execution of arbitrary code in ring 0, which is something that lock-down is meant to prevent. It makes sense to disable kexec_load() in this situation. This does not affect kexec_file_load() syscall which can check for a signature on the image to be booted. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Acked-by: Dave Young <dyoung@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org> cc: kexec@lists.infradead.org Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19lockdown: Restrict /dev/{mem,kmem,port} when the kernel is locked downMatthew Garrett
Allowing users to read and write to core kernel memory makes it possible for the kernel to be subverted, avoiding module loading restrictions, and also to steal cryptographic information. Disallow /dev/mem and /dev/kmem from being opened this when the kernel has been locked down to prevent this. Also disallow /dev/port from being opened to prevent raw ioport access and thus DMA from being used to accomplish the same thing. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: x86@kernel.org Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19lockdown: Enforce module signatures if the kernel is locked downDavid Howells
If the kernel is locked down, require that all modules have valid signatures that we can verify. I have adjusted the errors generated: (1) If there's no signature (ENODATA) or we can't check it (ENOPKG, ENOKEY), then: (a) If signatures are enforced then EKEYREJECTED is returned. (b) If there's no signature or we can't check it, but the kernel is locked down then EPERM is returned (this is then consistent with other lockdown cases). (2) If the signature is unparseable (EBADMSG, EINVAL), the signature fails the check (EKEYREJECTED) or a system error occurs (eg. ENOMEM), we return the error we got. Note that the X.509 code doesn't check for key expiry as the RTC might not be valid or might not have been transferred to the kernel's clock yet. [Modified by Matthew Garrett to remove the IMA integration. This will be replaced with integration with the IMA architecture policy patchset.] Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <matthewgarrett@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Jessica Yu <jeyu@kernel.org> Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19security: Add a static lockdown policy LSMMatthew Garrett
While existing LSMs can be extended to handle lockdown policy, distributions generally want to be able to apply a straightforward static policy. This patch adds a simple LSM that can be configured to reject either integrity or all lockdown queries, and can be configured at runtime (through securityfs), boot time (via a kernel parameter) or build time (via a kconfig option). Based on initial code by David Howells. Signed-off-by: Matthew Garrett <mjg59@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19security: Add a "locked down" LSM hookMatthew Garrett
Add a mechanism to allow LSMs to make a policy decision around whether kernel functionality that would allow tampering with or examining the runtime state of the kernel should be permitted. Signed-off-by: Matthew Garrett <mjg59@google.com> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19security: Support early LSMsMatthew Garrett
The lockdown module is intended to allow for kernels to be locked down early in boot - sufficiently early that we don't have the ability to kmalloc() yet. Add support for early initialisation of some LSMs, and then add them to the list of names when we do full initialisation later. Early LSMs are initialised in link order and cannot be overridden via boot parameters, and cannot make use of kmalloc() (since the allocator isn't initialised yet). (Fixed by Stephen Rothwell to include a stub to fix builds when !CONFIG_SECURITY) Signed-off-by: Matthew Garrett <mjg59@google.com> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: James Morris <jmorris@namei.org>
2019-08-13KEYS: trusted: allow module init if TPM is inactive or deactivatedRoberto Sassu
Commit c78719203fc6 ("KEYS: trusted: allow trusted.ko to initialize w/o a TPM") allows the trusted module to be loaded even if a TPM is not found, to avoid module dependency problems. However, trusted module initialization can still fail if the TPM is inactive or deactivated. tpm_get_random() returns an error. This patch removes the call to tpm_get_random() and instead extends the PCR specified by the user with zeros. The security of this alternative is equivalent to the previous one, as either option prevents with a PCR update unsealing and misuse of sealed data by a user space process. Even if a PCR is extended with zeros, instead of random data, it is still computationally infeasible to find a value as input for a new PCR extend operation, to obtain again the PCR value that would allow unsealing. Cc: stable@vger.kernel.org Fixes: 240730437deb ("KEYS: trusted: explicitly use tpm_chip structure...") Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> Reviewed-by: Tyler Hicks <tyhicks@canonical.com> Suggested-by: Mimi Zohar <zohar@linux.ibm.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
2019-08-12fanotify, inotify, dnotify, security: add security hook for fs notificationsAaron Goidel
As of now, setting watches on filesystem objects has, at most, applied a check for read access to the inode, and in the case of fanotify, requires CAP_SYS_ADMIN. No specific security hook or permission check has been provided to control the setting of watches. Using any of inotify, dnotify, or fanotify, it is possible to observe, not only write-like operations, but even read access to a file. Modeling the watch as being merely a read from the file is insufficient for the needs of SELinux. This is due to the fact that read access should not necessarily imply access to information about when another process reads from a file. Furthermore, fanotify watches grant more power to an application in the form of permission events. While notification events are solely, unidirectional (i.e. they only pass information to the receiving application), permission events are blocking. Permission events make a request to the receiving application which will then reply with a decision as to whether or not that action may be completed. This causes the issue of the watching application having the ability to exercise control over the triggering process. Without drawing a distinction within the permission check, the ability to read would imply the greater ability to control an application. Additionally, mount and superblock watches apply to all files within the same mount or superblock. Read access to one file should not necessarily imply the ability to watch all files accessed within a given mount or superblock. In order to solve these issues, a new LSM hook is implemented and has been placed within the system calls for marking filesystem objects with inotify, fanotify, and dnotify watches. These calls to the hook are placed at the point at which the target path has been resolved and are provided with the path struct, the mask of requested notification events, and the type of object on which the mark is being set (inode, superblock, or mount). The mask and obj_type have already been translated into common FS_* values shared by the entirety of the fs notification infrastructure. The path struct is passed rather than just the inode so that the mount is available, particularly for mount watches. This also allows for use of the hook by pathname-based security modules. However, since the hook is intended for use even by inode based security modules, it is not placed under the CONFIG_SECURITY_PATH conditional. Otherwise, the inode-based security modules would need to enable all of the path hooks, even though they do not use any of them. This only provides a hook at the point of setting a watch, and presumes that permission to set a particular watch implies the ability to receive all notification about that object which match the mask. This is all that is required for SELinux. If other security modules require additional hooks or infrastructure to control delivery of notification, these can be added by them. It does not make sense for us to propose hooks for which we have no implementation. The understanding that all notifications received by the requesting application are all strictly of a type for which the application has been granted permission shows that this implementation is sufficient in its coverage. Security modules wishing to provide complete control over fanotify must also implement a security_file_open hook that validates that the access requested by the watching application is authorized. Fanotify has the issue that it returns a file descriptor with the file mode specified during fanotify_init() to the watching process on event. This is already covered by the LSM security_file_open hook if the security module implements checking of the requested file mode there. Otherwise, a watching process can obtain escalated access to a file for which it has not been authorized. The selinux_path_notify hook implementation works by adding five new file permissions: watch, watch_mount, watch_sb, watch_reads, and watch_with_perm (descriptions about which will follow), and one new filesystem permission: watch (which is applied to superblock checks). The hook then decides which subset of these permissions must be held by the requesting application based on the contents of the provided mask and the obj_type. The selinux_file_open hook already checks the requested file mode and therefore ensures that a watching process cannot escalate its access through fanotify. The watch, watch_mount, and watch_sb permissions are the baseline permissions for setting a watch on an object and each are a requirement for any watch to be set on a file, mount, or superblock respectively. It should be noted that having either of the other two permissions (watch_reads and watch_with_perm) does not imply the watch, watch_mount, or watch_sb permission. Superblock watches further require the filesystem watch permission to the superblock. As there is no labeled object in view for mounts, there is no specific check for mount watches beyond watch_mount to the inode. Such a check could be added in the future, if a suitable labeled object existed representing the mount. The watch_reads permission is required to receive notifications from read-exclusive events on filesystem objects. These events include accessing a file for the purpose of reading and closing a file which has been opened read-only. This distinction has been drawn in order to provide a direct indication in the policy for this otherwise not obvious capability. Read access to a file should not necessarily imply the ability to observe read events on a file. Finally, watch_with_perm only applies to fanotify masks since it is the only way to set a mask which allows for the blocking, permission event. This permission is needed for any watch which is of this type. Though fanotify requires CAP_SYS_ADMIN, this is insufficient as it gives implicit trust to root, which we do not do, and does not support least privilege. Signed-off-by: Aaron Goidel <acgoide@tycho.nsa.gov> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Paul Moore <paul@paul-moore.com>