Back then, commit 96ae522795 ("bpf: Add bpf_probe_write_user BPF helper
to be called in tracers") added the bpf_probe_write_user() helper in order
to allow to override user space memory. Its original goal was to have a
facility to "debug, divert, and manipulate execution of semi-cooperative
processes" under CAP_SYS_ADMIN. Write to kernel was explicitly disallowed
since it would otherwise tamper with its integrity.
One use case was shown in cf9b1199de ("samples/bpf: Add test/example of
using bpf_probe_write_user bpf helper") where the program DNATs traffic
at the time of connect(2) syscall, meaning, it rewrites the arguments to
a syscall while they're still in userspace, and before the syscall has a
chance to copy the argument into kernel space. These days we have better
mechanisms in BPF for achieving the same (e.g. for load-balancers), but
without having to write to userspace memory.
Of course the bpf_probe_write_user() helper can also be used to abuse
many other things for both good or bad purpose. Outside of BPF, there is
a similar mechanism for ptrace(2) such as PTRACE_PEEK{TEXT,DATA} and
PTRACE_POKE{TEXT,DATA}, but would likely require some more effort.
Commit 96ae522795 explicitly dedicated the helper for experimentation
purpose only. Thus, move the helper's availability behind a newly added
LOCKDOWN_BPF_WRITE_USER lockdown knob so that the helper is disabled under
the "integrity" mode. More fine-grained control can be implemented also
from LSM side with this change.
Fixes: 96ae522795 ("bpf: Add bpf_probe_write_user BPF helper to be called in tracers")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Rename LOCKDOWN_BPF_READ into LOCKDOWN_BPF_READ_KERNEL so we have naming
more consistent with a LOCKDOWN_BPF_WRITE_USER option that we are adding.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Pull selinux fix from Paul Moore:
"One small SELinux fix for a problem where an error code was not being
propagated back up to userspace when a bogus SELinux policy is loaded
into the kernel"
* tag 'selinux-pr-20210805' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
selinux: correct the return value when loads initial sids
It should not return 0 when SID 0 is assigned to isids.
This patch fixes it.
Cc: stable@vger.kernel.org
Fixes: e3e0b582c3 ("selinux: remove unused initial SIDs and improve handling")
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
[PM: remove changelog from description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Pull asm/unaligned.h unification from Arnd Bergmann:
"Unify asm/unaligned.h around struct helper
The get_unaligned()/put_unaligned() helpers are traditionally
architecture specific, with the two main variants being the
"access-ok.h" version that assumes unaligned pointer accesses always
work on a particular architecture, and the "le-struct.h" version that
casts the data to a byte aligned type before dereferencing, for
architectures that cannot always do unaligned accesses in hardware.
Based on the discussion linked below, it appears that the access-ok
version is not realiable on any architecture, but the struct version
probably has no downsides. This series changes the code to use the
same implementation on all architectures, addressing the few
exceptions separately"
Link: https://lore.kernel.org/lkml/75d07691-1e4f-741f-9852-38c0b4f520bc@synopsys.com/
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100363
Link: https://lore.kernel.org/lkml/20210507220813.365382-14-arnd@kernel.org/
Link: git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic.git unaligned-rework-v2
Link: https://lore.kernel.org/lkml/CAHk-=whGObOKruA_bU3aPGZfoDqZM1_9wBkwREp0H0FgR-90uQ@mail.gmail.com/
* tag 'asm-generic-unaligned-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
asm-generic: simplify asm/unaligned.h
asm-generic: uaccess: 1-byte access is always aligned
netpoll: avoid put_unaligned() on single character
mwifiex: re-fix for unaligned accesses
apparmor: use get_unaligned() only for multi-byte words
partitions: msdos: fix one-byte get_unaligned()
asm-generic: unaligned always use struct helpers
asm-generic: unaligned: remove byteshift helpers
powerpc: use linux/unaligned/le_struct.h on LE power7
m68k: select CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
sh: remove unaligned access for sh4a
openrisc: always use unaligned-struct header
asm-generic: use asm-generic/unaligned.h for most architectures
Pull SafeSetID update from Micah Morton:
"One very minor code cleanup change that marks a variable as
__initdata"
* tag 'safesetid-5.14' of git://github.com/micah-morton/linux:
LSM: SafeSetID: Mark safesetid_initialized as __initdata
Pull smack updates from Casey Schaufler:
"There is nothing more significant than an improvement to a byte count
check in smackfs.
All changes have been in next for weeks"
* tag 'Smack-for-5.14' of git://github.com/cschaufler/smack-next:
Smack: fix doc warning
Revert "Smack: Handle io_uring kernel thread privileges"
smackfs: restrict bytes count in smk_set_cipso()
security/smack/: fix misspellings using codespell tool
Pull audit updates from Paul Moore:
"Another merge window, another small audit pull request.
Four patches in total: one is cosmetic, one removes an unnecessary
initialization, one renames some enum values to prevent name
collisions, and one converts list_del()/list_add() to list_move().
None of these are earth shattering and all pass the audit-testsuite
tests while merging cleanly on top of your tree from earlier today"
* tag 'audit-pr-20210629' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit:
audit: remove unnecessary 'ret' initialization
audit: remove trailing spaces and tabs
audit: Use list_move instead of list_del/list_add
audit: Rename enum audit_state constants to avoid AUDIT_DISABLED redefinition
audit: add blank line after variable declarations
Pull SELinux updates from Paul Moore:
- The slow_avc_audit() function is now non-blocking so we can remove
the AVC_NONBLOCKING tricks; this also includes the 'flags' variant of
avc_has_perm().
- Use kmemdup() instead of kcalloc()+copy when copying parts of the
SELinux policydb.
- The InfiniBand device name is now passed by reference when possible
in the SELinux code, removing a strncpy().
- Minor cleanups including: constification of avtab function args,
removal of useless LSM/XFRM function args, SELinux kdoc fixes, and
removal of redundant assignments.
* tag 'selinux-pr-20210629' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
selinux: kill 'flags' argument in avc_has_perm_flags() and avc_audit()
selinux: slow_avc_audit has become non-blocking
selinux: Fix kernel-doc
selinux: use __GFP_NOWARN with GFP_NOWAIT in the AVC
lsm_audit,selinux: pass IB device name by reference
selinux: Remove redundant assignment to rc
selinux: Corrected comment to match kernel-doc comment
selinux: delete selinux_xfrm_policy_lookup() useless argument
selinux: constify some avtab function arguments
selinux: simplify duplicate_policydb_cond_list() by using kmemdup()
Pull integrity subsystem updates from Mimi Zohar:
"The large majority of the changes are EVM portable & immutable
signature related: removing a dependency on loading an HMAC key,
safely allowing file metadata included in the EVM portable & immutable
signatures to be modified, allowing EVM signatures to fulfill IMA file
signature policy requirements, including the EVM file metadata
signature in lieu of an IMA file data signature in the measurement
list, and adding dynamic debugging of EVM file metadata.
In addition, in order to detect critical data or file change
reversions, duplicate measurement records are permitted in the IMA
measurement list.
The remaining patches address compiler, sparse, and doc warnings"
* tag 'integrity-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity: (31 commits)
evm: Check xattr size discrepancy between kernel and user
evm: output EVM digest calculation info
IMA: support for duplicate measurement records
ima: Fix warning: no previous prototype for function 'ima_add_kexec_buffer'
ima: differentiate between EVM failures in the audit log
ima: Fix fall-through warning for Clang
ima: Pass NULL instead of 0 to ima_get_action() in ima_file_mprotect()
ima: Include header defining ima_post_key_create_or_update()
ima/evm: Fix type mismatch
ima: Set correct casting types
doc: Fix warning in Documentation/security/IMA-templates.rst
evm: Don't return an error in evm_write_xattrs() if audit is not enabled
ima: Define new template evm-sig
ima: Define new template fields xattrnames, xattrlengths and xattrvalues
evm: Verify portable signatures against all protected xattrs
ima: Define new template field imode
ima: Define new template fields iuid and igid
ima: Add ima_show_template_uint() template library function
ima: Don't remove security.ima if file must not be appraised
ima: Introduce template field evmsig and write to field sig as fallback
...
The kernel and the user obtain an xattr value in two different ways:
kernel (EVM): uses vfs_getxattr_alloc() which obtains the xattr value from
the filesystem handler (raw value);
user (ima-evm-utils): uses vfs_getxattr() which obtains the xattr value
from the LSMs (normalized value).
Normally, this does not have an impact unless security.selinux is set with
setfattr, with a value not terminated by '\0' (this is not the recommended
way, security.selinux should be set with the appropriate tools such as
chcon and restorecon).
In this case, the kernel and the user see two different xattr values: the
former sees the xattr value without '\0' (raw value), the latter sees the
value with '\0' (value normalized by SELinux).
This could result in two different verification outcomes from EVM and
ima-evm-utils, if a signature was calculated with a security.selinux value
terminated by '\0' and the value set in the filesystem is not terminated by
'\0'. The former would report verification failure due to the missing '\0',
while the latter would report verification success (because it gets the
normalized value with '\0').
This patch mitigates this issue by comparing in evm_calc_hmac_or_hash() the
size of the xattr returned by the two xattr functions and by warning the
user if there is a discrepancy.
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Output the data used in calculating the EVM digest and the resulting
digest as ascii hexadecimal strings.
Suggested-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com> (CONFIG_DYNAMIC_DEBUG)
Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Reported-by: kernel test robot <lkp@intel.com> (Use %zu for size_t)
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Fix gcc W=1 warnings:
security/tomoyo/audit.c:331: warning: Function parameter or member 'matched_acl' not described in 'tomoyo_get_audit'
security/tomoyo/securityfs_if.c:146: warning: Function parameter or member 'inode' not described in 'tomoyo_release'
security/tomoyo/tomoyo.c:122: warning: Function parameter or member 'path' not described in 'tomoyo_inode_getattr'
security/tomoyo/tomoyo.c:497: warning: Function parameter or member 'clone_flags' not described in 'tomoyo_task_alloc'
security/tomoyo/util.c:92: warning: Function parameter or member 'time64' not described in 'tomoyo_convert_time'
Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>
[ penguin-kernel: Also adjust spaces and similar warnings ]
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
The variable 'ret' is set to 0 when declared.
The 'ret' is unused until it is set to 0 again.
So it had better remove unnecessary initialization.
Signed-off-by: Austin Kim <austin.kim@lge.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
... along with avc_has_perm_flags() itself, since now it's identical
to avc_has_perm() (as pointed out by Paul Moore)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[PM: add "selinux:" prefix to subj and tweak for length]
Signed-off-by: Paul Moore <paul@paul-moore.com>
dump_common_audit_data() is safe to use under rcu_read_lock() now;
no need for AVC_NONBLOCKING and games around it
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Fix function name and add comment for parameter state in ss/services.c
kernel-doc to remove some warnings found by running make W=1 LLVM=1.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
IMA measures contents of a given file/buffer/critical-data record,
and properly re-measures it on change. However, IMA does not measure
the duplicate value for a given record, since TPM extend is a very
expensive operation. For example, if the record changes from value
'v#1' to 'v#2', and then back to 'v#1', IMA will not measure and log
the last change to 'v#1', since the hash of 'v#1' for that record is
already present in the IMA htable. This limits the ability of an
external attestation service to accurately determine the current state
of the system. The service would incorrectly conclude that the latest
value of the given record on the system is 'v#2', and act accordingly.
Define and use a new Kconfig option IMA_DISABLE_HTABLE to permit
duplicate records in the IMA measurement list.
In addition to the duplicate measurement records described above,
other duplicate file measurement records may be included in the log,
when CONFIG_IMA_DISABLE_HTABLE is enabled. For example,
- i_version is not enabled,
- i_generation changed,
- same file present on different filesystems,
- an inode is evicted from dcache
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
[zohar@linux.ibm.com: updated list of duplicate measurement records]
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
The function prototype for ima_add_kexec_buffer() is present
in 'linux/ima.h'. But this header file is not included in
ima_kexec.c where the function is implemented. This results
in the following compiler warning when "-Wmissing-prototypes" flag
is turned on:
security/integrity/ima/ima_kexec.c:81:6: warning: no previous prototype
for function 'ima_add_kexec_buffer' [-Wmissing-prototypes]
Include the header file 'linux/ima.h' in ima_kexec.c to fix
the compiler warning.
Fixes: dce92f6b11 (arm64: Enable passing IMA log to next kernel on kexec)
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Mark safesetid_initialized as __initdata since it is only used
in initialization routine.
Signed-off-by: Austin Kim <austindh.kim@gmail.com>
Signed-off-by: Micah Morton <mortonm@chromium.org>
This patch fixes the sparse warning for ima_post_key_create_or_update() by
adding the header file that defines the prototype (linux/ima.h).
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
