linux/security
Roberto Sassu 1886ab01a3 evm: Allow setxattr() and setattr() for unmodified metadata
With the patch to allow xattr/attr operations if a portable signature
verification fails, cp and tar can copy all xattrs/attrs so that at the
end of the process verification succeeds.

However, it might happen that the xattrs/attrs are already set to the
correct value (taken at signing time) and signature verification succeeds
before the copy has completed. For example, an archive might contains files
owned by root and the archive is extracted by root.

Then, since portable signatures are immutable, all subsequent operations
fail (e.g. fchown()), even if the operation is legitimate (does not alter
the current value).

This patch avoids this problem by reporting successful operation to user
space when that operation does not alter the current value of xattrs/attrs.

With this patch, the one that introduces evm_hmac_disabled() and the one
that allows a metadata operation on the INTEGRITY_FAIL_IMMUTABLE error, EVM
portable signatures can be used without disabling metadata verification
(by setting EVM_ALLOW_METADATA_WRITES). Due to keeping metadata
verification enabled, altering immutable metadata protected with a portable
signature that was successfully verified will be denied (existing
behavior).

Reported-by: kernel test robot <lkp@intel.com> [implicit declaration of function]
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2021-06-01 12:28:34 -04:00
..
apparmor Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-05-02 09:14:01 -07:00
bpf bpf: Implement task local storage 2020-11-06 08:08:37 -08:00
integrity evm: Allow setxattr() and setattr() for unmodified metadata 2021-06-01 12:28:34 -04:00
keys trusted-keys: match tpm_get_ops on all return paths 2021-05-12 22:36:37 +03:00
landlock landlock: Enable user space to infer supported features 2021-04-22 12:22:11 -07:00
loadpin LSM: Add "contents" flag to kernel_read_file hook 2020-10-05 13:37:03 +02:00
lockdown Merge branch 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2020-06-02 17:36:24 -07:00
safesetid LSM: SafeSetID: Fix code specification by scripts/checkpatch.pl 2021-04-26 16:36:50 -07:00
selinux Add Landlock, a new LSM from Mickaël Salaün <mic@linux.microsoft.com> 2021-05-01 18:50:44 -07:00
smack Add Landlock, a new LSM from Mickaël Salaün <mic@linux.microsoft.com> 2021-05-01 18:50:44 -07:00
tomoyo tomoyo: don't special case PF_IO_WORKER for PF_KTHREAD 2021-03-28 13:11:29 +09:00
yama task_work: cleanup notification modes 2020-10-17 15:05:30 -06:00
commoncap.c Miscellaneous minor fixes for v5.13. 2021-04-27 19:32:55 -07:00
device_cgroup.c device_cgroup: Fix RCU list debugging warning 2020-08-20 11:25:03 -07:00
inode.c Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
Kconfig landlock: Set up the security framework and manage credentials 2021-04-22 12:22:10 -07:00
Kconfig.hardening kasan: remove redundant config option 2021-04-16 16:10:36 -07:00
lsm_audit.c make dump_common_audit_data() safe to be called from RCU pathwalk 2021-01-16 15:12:08 -05:00
Makefile landlock: Add object management 2021-04-22 12:22:10 -07:00
min_addr.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
security.c evm: Pass user namespace to set/remove xattr hooks 2021-05-21 12:57:52 -04:00