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2021-03-22Merge tag 'selinux-pr-20210322' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux Pull selinux fixes from Paul Moore: "Three SELinux patches: - Fix a problem where a local variable is used outside its associated function. Thankfully this can only be triggered by reloading the SELinux policy, which is a restricted operation for other obvious reasons. - Fix some incorrect, and inconsistent, audit and printk messages when loading the SELinux policy. All three patches are relatively minor and have been through our testing with no failures" * tag 'selinux-pr-20210322' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux: selinuxfs: unify policy load error reporting selinux: fix variable scope issue in live sidtab conversion selinux: don't log MAC_POLICY_LOAD record on failed policy load
2021-03-18selinuxfs: unify policy load error reportingOndrej Mosnacek
Let's drop the pr_err()s from sel_make_policy_nodes() and just add one pr_warn_ratelimited() call to the sel_make_policy_nodes() error path in sel_write_load(). Changing from error to warning makes sense, since after 02a52c5c8c3b ("selinux: move policy commit after updating selinuxfs"), this error path no longer leads to a broken selinuxfs tree (it's just kept in the original state and policy load is aborted). I also added _ratelimited to be consistent with the other prtin in the same function (it's probably not necessary, but can't really hurt... there are likely more important error messages to be printed when filesystem entry creation starts erroring out). Suggested-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-03-18selinux: fix variable scope issue in live sidtab conversionOndrej Mosnacek
Commit 02a52c5c8c3b ("selinux: move policy commit after updating selinuxfs") moved the selinux_policy_commit() call out of security_load_policy() into sel_write_load(), which caused a subtle yet rather serious bug. The problem is that security_load_policy() passes a reference to the convert_params local variable to sidtab_convert(), which stores it in the sidtab, where it may be accessed until the policy is swapped over and RCU synchronized. Before 02a52c5c8c3b, selinux_policy_commit() was called directly from security_load_policy(), so the convert_params pointer remained valid all the way until the old sidtab was destroyed, but now that's no longer the case and calls to sidtab_context_to_sid() on the old sidtab after security_load_policy() returns may cause invalid memory accesses. This can be easily triggered using the stress test from commit ee1a84fdfeed ("selinux: overhaul sidtab to fix bug and improve performance"): ``` function rand_cat() { echo $(( $RANDOM % 1024 )) } function do_work() { while true; do echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \ >/sys/fs/selinux/context 2>/dev/null || true done } do_work >/dev/null & do_work >/dev/null & do_work >/dev/null & while load_policy; do echo -n .; sleep 0.1; done kill %1 kill %2 kill %3 ``` Fix this by allocating the temporary sidtab convert structures dynamically and passing them among the selinux_policy_{load,cancel,commit} functions. Fixes: 02a52c5c8c3b ("selinux: move policy commit after updating selinuxfs") Cc: stable@vger.kernel.org Tested-by: Tyler Hicks <tyhicks@linux.microsoft.com> Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com> Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> [PM: merge fuzz in security.h and services.c] Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-03-18selinux: don't log MAC_POLICY_LOAD record on failed policy loadOndrej Mosnacek
If sel_make_policy_nodes() fails, we should jump to 'out', not 'out1', as the latter would incorrectly log an MAC_POLICY_LOAD audit record, even though the policy hasn't actually been reloaded. The 'out1' jump label now becomes unused and can be removed. Fixes: 02a52c5c8c3b ("selinux: move policy commit after updating selinuxfs") Cc: stable@vger.kernel.org Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-03-11nexthop: Add netlink defines and enumerators for resilient NH groupsIdo Schimmel
- RTM_NEWNEXTHOP et.al. that handle resilient groups will have a new nested attribute, NHA_RES_GROUP, whose elements are attributes NHA_RES_GROUP_*. - RTM_NEWNEXTHOPBUCKET et.al. is a suite of new messages that will currently serve only for dumping of individual buckets of resilient next hop groups. For nexthop group buckets, these messages will carry a nested attribute NHA_RES_BUCKET, whose elements are attributes NHA_RES_BUCKET_*. There are several reasons why a new suite of messages is created for nexthop buckets instead of overloading the information on the existing RTM_{NEW,DEL,GET}NEXTHOP messages. First, a nexthop group can contain a large number of nexthop buckets (4k is not unheard of). This imposes limits on the amount of information that can be encoded for each nexthop bucket given a netlink message is limited to 64k bytes. Second, while RTM_NEWNEXTHOPBUCKET is only used for notifications at this point, in the future it can be extended to provide user space with control over nexthop buckets configuration. - The new group type is NEXTHOP_GRP_TYPE_RES. Note that nexthop code is adjusted to bounce groups with that type for now. Signed-off-by: Ido Schimmel <idosch@nvidia.com> Reviewed-by: Petr Machata <petrm@nvidia.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: Petr Machata <petrm@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2021-03-08selinux: fix misspellings using codespell toolXiong Zhenwu
A typo is f out by codespell tool in 422th line of security.h: $ codespell ./security/selinux/include/ ./security.h:422: thie ==> the, this Fix a typo found by codespell. Signed-off-by: Xiong Zhenwu <xiong.zhenwu@zte.com.cn> [PM: subject line tweaks] Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-03-08selinux: fix misspellings using codespell toolXiong Zhenwu
A typo is found out by codespell tool in 16th line of hashtab.c $ codespell ./security/selinux/ss/ ./hashtab.c:16: rouding ==> rounding Fix a typo found by codespell. Signed-off-by: Xiong Zhenwu <xiong.zhenwu@zte.com.cn> [PM: subject line tweak] Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-03-08selinux: measure state and policy capabilitiesLakshmi Ramasubramanian
SELinux stores the configuration state and the policy capabilities in kernel memory. Changes to this data at runtime would have an impact on the security guarantees provided by SELinux. Measuring this data through IMA subsystem provides a tamper-resistant way for an attestation service to remotely validate it at runtime. Measure the configuration state and policy capabilities by calling the IMA hook ima_measure_critical_data(). To enable SELinux data measurement, the following steps are required: 1, Add "ima_policy=critical_data" to the kernel command line arguments to enable measuring SELinux data at boot time. For example, BOOT_IMAGE=/boot/vmlinuz-5.11.0-rc3+ root=UUID=fd643309-a5d2-4ed3-b10d-3c579a5fab2f ro nomodeset security=selinux ima_policy=critical_data 2, Add the following rule to /etc/ima/ima-policy measure func=CRITICAL_DATA label=selinux Sample measurement of SELinux state and policy capabilities: 10 2122...65d8 ima-buf sha256:13c2...1292 selinux-state 696e...303b Execute the following command to extract the measured data from the IMA's runtime measurements list: grep "selinux-state" /sys/kernel/security/integrity/ima/ascii_runtime_measurements | tail -1 | cut -d' ' -f 6 | xxd -r -p The output should be a list of key-value pairs. For example, initialized=1;enforcing=0;checkreqprot=1;network_peer_controls=1;open_perms=1;extended_socket_class=1;always_check_network=0;cgroup_seclabel=1;nnp_nosuid_transition=1;genfs_seclabel_symlinks=0; To verify the measurement is consistent with the current SELinux state reported on the system, compare the integer values in the following files with those set in the IMA measurement (using the following commands): - cat /sys/fs/selinux/enforce - cat /sys/fs/selinux/checkreqprot - cat /sys/fs/selinux/policy_capabilities/[capability_file] Note that the actual verification would be against an expected state and done on a separate system (likely an attestation server) requiring "initialized=1;enforcing=1;checkreqprot=0;" for a secure state and then whatever policy capabilities are actually set in the expected policy (which can be extracted from the policy itself via seinfo, for example). Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com> Suggested-by: Stephen Smalley <stephen.smalley.work@gmail.com> Suggested-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-03-08selinux: Allow context mounts for unpriviliged overlayfsVivek Goyal
Now overlayfs allow unpriviliged mounts. That is root inside a non-init user namespace can mount overlayfs. This is being added in 5.11 kernel. Giuseppe tried to mount overlayfs with option "context" and it failed with error -EACCESS. $ su test $ unshare -rm $ mkdir -p lower upper work merged $ mount -t overlay -o lowerdir=lower,workdir=work,upperdir=upper,userxattr,context='system_u:object_r:container_file_t:s0' none merged This fails with -EACCESS. It works if option "-o context" is not specified. Little debugging showed that selinux_set_mnt_opts() returns -EACCESS. So this patch adds "overlay" to the list, where it is fine to specific context from non init_user_ns. Reported-by: Giuseppe Scrivano <gscrivan@redhat.com> Signed-off-by: Vivek Goyal <vgoyal@redhat.com> [PM: trimmed the changelog from the description] Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-02-23Merge tag 'idmapped-mounts-v5.12' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux Pull idmapped mounts from Christian Brauner: "This introduces idmapped mounts which has been in the making for some time. Simply put, different mounts can expose the same file or directory with different ownership. This initial implementation comes with ports for fat, ext4 and with Christoph's port for xfs with more filesystems being actively worked on by independent people and maintainers. Idmapping mounts handle a wide range of long standing use-cases. Here are just a few: - Idmapped mounts make it possible to easily share files between multiple users or multiple machines especially in complex scenarios. For example, idmapped mounts will be used in the implementation of portable home directories in systemd-homed.service(8) where they allow users to move their home directory to an external storage device and use it on multiple computers where they are assigned different uids and gids. This effectively makes it possible to assign random uids and gids at login time. - It is possible to share files from the host with unprivileged containers without having to change ownership permanently through chown(2). - It is possible to idmap a container's rootfs and without having to mangle every file. For example, Chromebooks use it to share the user's Download folder with their unprivileged containers in their Linux subsystem. - It is possible to share files between containers with non-overlapping idmappings. - Filesystem that lack a proper concept of ownership such as fat can use idmapped mounts to implement discretionary access (DAC) permission checking. - They allow users to efficiently changing ownership on a per-mount basis without having to (recursively) chown(2) all files. In contrast to chown (2) changing ownership of large sets of files is instantenous with idmapped mounts. This is especially useful when ownership of a whole root filesystem of a virtual machine or container is changed. With idmapped mounts a single syscall mount_setattr syscall will be sufficient to change the ownership of all files. - Idmapped mounts always take the current ownership into account as idmappings specify what a given uid or gid is supposed to be mapped to. This contrasts with the chown(2) syscall which cannot by itself take the current ownership of the files it changes into account. It simply changes the ownership to the specified uid and gid. This is especially problematic when recursively chown(2)ing a large set of files which is commong with the aforementioned portable home directory and container and vm scenario. - Idmapped mounts allow to change ownership locally, restricting it to specific mounts, and temporarily as the ownership changes only apply as long as the mount exists. Several userspace projects have either already put up patches and pull-requests for this feature or will do so should you decide to pull this: - systemd: In a wide variety of scenarios but especially right away in their implementation of portable home directories. https://systemd.io/HOME_DIRECTORY/ - container runtimes: containerd, runC, LXD:To share data between host and unprivileged containers, unprivileged and privileged containers, etc. The pull request for idmapped mounts support in containerd, the default Kubernetes runtime is already up for quite a while now: https://github.com/containerd/containerd/pull/4734 - The virtio-fs developers and several users have expressed interest in using this feature with virtual machines once virtio-fs is ported. - ChromeOS: Sharing host-directories with unprivileged containers. I've tightly synced with all those projects and all of those listed here have also expressed their need/desire for this feature on the mailing list. For more info on how people use this there's a bunch of talks about this too. Here's just two recent ones: https://www.cncf.io/wp-content/uploads/2020/12/Rootless-Containers-in-Gitpod.pdf https://fosdem.org/2021/schedule/event/containers_idmap/ This comes with an extensive xfstests suite covering both ext4 and xfs: https://git.kernel.org/brauner/xfstests-dev/h/idmapped_mounts It covers truncation, creation, opening, xattrs, vfscaps, setid execution, setgid inheritance and more both with idmapped and non-idmapped mounts. It already helped to discover an unrelated xfs setgid inheritance bug which has since been fixed in mainline. It will be sent for inclusion with the xfstests project should you decide to merge this. In order to support per-mount idmappings vfsmounts are marked with user namespaces. The idmapping of the user namespace will be used to map the ids of vfs objects when they are accessed through that mount. By default all vfsmounts are marked with the initial user namespace. The initial user namespace is used to indicate that a mount is not idmapped. All operations behave as before and this is verified in the testsuite. Based on prior discussions we want to attach the whole user namespace and not just a dedicated idmapping struct. This allows us to reuse all the helpers that already exist for dealing with idmappings instead of introducing a whole new range of helpers. In addition, if we decide in the future that we are confident enough to enable unprivileged users to setup idmapped mounts the permission checking can take into account whether the caller is privileged in the user namespace the mount is currently marked with. The user namespace the mount will be marked with can be specified by passing a file descriptor refering to the user namespace as an argument to the new mount_setattr() syscall together with the new MOUNT_ATTR_IDMAP flag. The system call follows the openat2() pattern of extensibility. The following conditions must be met in order to create an idmapped mount: - The caller must currently have the CAP_SYS_ADMIN capability in the user namespace the underlying filesystem has been mounted in. - The underlying filesystem must support idmapped mounts. - The mount must not already be idmapped. This also implies that the idmapping of a mount cannot be altered once it has been idmapped. - The mount must be a detached/anonymous mount, i.e. it must have been created by calling open_tree() with the OPEN_TREE_CLONE flag and it must not already have been visible in the filesystem. The last two points guarantee easier semantics for userspace and the kernel and make the implementation significantly simpler. By default vfsmounts are marked with the initial user namespace and no behavioral or performance changes are observed. The manpage with a detailed description can be found here: https://git.kernel.org/brauner/man-pages/c/1d7b902e2875a1ff342e036a9f866a995640aea8 In order to support idmapped mounts, filesystems need to be changed and mark themselves with the FS_ALLOW_IDMAP flag in fs_flags. The patches to convert individual filesystem are not very large or complicated overall as can be seen from the included fat, ext4, and xfs ports. Patches for other filesystems are actively worked on and will be sent out separately. The xfstestsuite can be used to verify that port has been done correctly. The mount_setattr() syscall is motivated independent of the idmapped mounts patches and it's been around since July 2019. One of the most valuable features of the new mount api is the ability to perform mounts based on file descriptors only. Together with the lookup restrictions available in the openat2() RESOLVE_* flag namespace which we added in v5.6 this is the first time we are close to hardened and race-free (e.g. symlinks) mounting and path resolution. While userspace has started porting to the new mount api to mount proper filesystems and create new bind-mounts it is currently not possible to change mount options of an already existing bind mount in the new mount api since the mount_setattr() syscall is missing. With the addition of the mount_setattr() syscall we remove this last restriction and userspace can now fully port to the new mount api, covering every use-case the old mount api could. We also add the crucial ability to recursively change mount options for a whole mount tree, both removing and adding mount options at the same time. This syscall has been requested multiple times by various people and projects. There is a simple tool available at https://github.com/brauner/mount-idmapped that allows to create idmapped mounts so people can play with this patch series. I'll add support for the regular mount binary should you decide to pull this in the following weeks: Here's an example to a simple idmapped mount of another user's home directory: u1001@f2-vm:/$ sudo ./mount --idmap both:1000:1001:1 /home/ubuntu/ /mnt u1001@f2-vm:/$ ls -al /home/ubuntu/ total 28 drwxr-xr-x 2 ubuntu ubuntu 4096 Oct 28 22:07 . drwxr-xr-x 4 root root 4096 Oct 28 04:00 .. -rw------- 1 ubuntu ubuntu 3154 Oct 28 22:12 .bash_history -rw-r--r-- 1 ubuntu ubuntu 220 Feb 25 2020 .bash_logout -rw-r--r-- 1 ubuntu ubuntu 3771 Feb 25 2020 .bashrc -rw-r--r-- 1 ubuntu ubuntu 807 Feb 25 2020 .profile -rw-r--r-- 1 ubuntu ubuntu 0 Oct 16 16:11 .sudo_as_admin_successful -rw------- 1 ubuntu ubuntu 1144 Oct 28 00:43 .viminfo u1001@f2-vm:/$ ls -al /mnt/ total 28 drwxr-xr-x 2 u1001 u1001 4096 Oct 28 22:07 . drwxr-xr-x 29 root root 4096 Oct 28 22:01 .. -rw------- 1 u1001 u1001 3154 Oct 28 22:12 .bash_history -rw-r--r-- 1 u1001 u1001 220 Feb 25 2020 .bash_logout -rw-r--r-- 1 u1001 u1001 3771 Feb 25 2020 .bashrc -rw-r--r-- 1 u1001 u1001 807 Feb 25 2020 .profile -rw-r--r-- 1 u1001 u1001 0 Oct 16 16:11 .sudo_as_admin_successful -rw------- 1 u1001 u1001 1144 Oct 28 00:43 .viminfo u1001@f2-vm:/$ touch /mnt/my-file u1001@f2-vm:/$ setfacl -m u:1001:rwx /mnt/my-file u1001@f2-vm:/$ sudo setcap -n 1001 cap_net_raw+ep /mnt/my-file u1001@f2-vm:/$ ls -al /mnt/my-file -rw-rwxr--+ 1 u1001 u1001 0 Oct 28 22:14 /mnt/my-file u1001@f2-vm:/$ ls -al /home/ubuntu/my-file -rw-rwxr--+ 1 ubuntu ubuntu 0 Oct 28 22:14 /home/ubuntu/my-file u1001@f2-vm:/$ getfacl /mnt/my-file getfacl: Removing leading '/' from absolute path names # file: mnt/my-file # owner: u1001 # group: u1001 user::rw- user:u1001:rwx group::rw- mask::rwx other::r-- u1001@f2-vm:/$ getfacl /home/ubuntu/my-file getfacl: Removing leading '/' from absolute path names # file: home/ubuntu/my-file # owner: ubuntu # group: ubuntu user::rw- user:ubuntu:rwx group::rw- mask::rwx other::r--" * tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: (41 commits) xfs: remove the possibly unused mp variable in xfs_file_compat_ioctl xfs: support idmapped mounts ext4: support idmapped mounts fat: handle idmapped mounts tests: add mount_setattr() selftests fs: introduce MOUNT_ATTR_IDMAP fs: add mount_setattr() fs: add attr_flags_to_mnt_flags helper fs: split out functions to hold writers namespace: only take read lock in do_reconfigure_mnt() mount: make {lock,unlock}_mount_hash() static namespace: take lock_mount_hash() directly when changing flags nfs: do not export idmapped mounts overlayfs: do not mount on top of idmapped mounts ecryptfs: do not mount on top of idmapped mounts ima: handle idmapped mounts apparmor: handle idmapped mounts fs: make helpers idmap mount aware exec: handle idmapped mounts would_dump: handle idmapped mounts ...
2021-02-21Merge tag 'integrity-v5.12' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity Pull IMA updates from Mimi Zohar: "New is IMA support for measuring kernel critical data, as per usual based on policy. The first example measures the in memory SELinux policy. The second example measures the kernel version. In addition are four bug fixes to address memory leaks and a missing 'static' function declaration" * tag 'integrity-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity: integrity: Make function integrity_add_key() static ima: Free IMA measurement buffer after kexec syscall ima: Free IMA measurement buffer on error IMA: Measure kernel version in early boot selinux: include a consumer of the new IMA critical data hook IMA: define a builtin critical data measurement policy IMA: extend critical data hook to limit the measurement based on a label IMA: limit critical data measurement based on a label IMA: add policy rule to measure critical data IMA: define a hook to measure kernel integrity critical data IMA: add support to measure buffer data hash IMA: generalize keyring specific measurement constructs evm: Fix memleak in init_desc
2021-01-24commoncap: handle idmapped mountsChristian Brauner
When interacting with user namespace and non-user namespace aware filesystem capabilities the vfs will perform various security checks to determine whether or not the filesystem capabilities can be used by the caller, whether they need to be removed and so on. The main infrastructure for this resides in the capability codepaths but they are called through the LSM security infrastructure even though they are not technically an LSM or optional. This extends the existing security hooks security_inode_removexattr(), security_inode_killpriv(), security_inode_getsecurity() to pass down the mount's user namespace and makes them aware of idmapped mounts. In order to actually get filesystem capabilities from disk the capability infrastructure exposes the get_vfs_caps_from_disk() helper. For user namespace aware filesystem capabilities a root uid is stored alongside the capabilities. In order to determine whether the caller can make use of the filesystem capability or whether it needs to be ignored it is translated according to the superblock's user namespace. If it can be translated to uid 0 according to that id mapping the caller can use the filesystem capabilities stored on disk. If we are accessing the inode that holds the filesystem capabilities through an idmapped mount we map the root uid according to the mount's user namespace. Afterwards the checks are identical to non-idmapped mounts: reading filesystem caps from disk enforces that the root uid associated with the filesystem capability must have a mapping in the superblock's user namespace and that the caller is either in the same user namespace or is a descendant of the superblock's user namespace. For filesystems that are mountable inside user namespace the caller can just mount the filesystem and won't usually need to idmap it. If they do want to idmap it they can create an idmapped mount and mark it with a user namespace they created and which is thus a descendant of s_user_ns. For filesystems that are not mountable inside user namespaces the descendant rule is trivially true because the s_user_ns will be the initial user namespace. If the initial user namespace is passed nothing changes so non-idmapped mounts will see identical behavior as before. Link: https://lore.kernel.org/r/20210121131959.646623-11-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-24xattr: handle idmapped mountsTycho Andersen
When interacting with extended attributes the vfs verifies that the caller is privileged over the inode with which the extended attribute is associated. For posix access and posix default extended attributes a uid or gid can be stored on-disk. Let the functions handle posix extended attributes on idmapped mounts. If the inode is accessed through an idmapped mount we need to map it according to the mount's user namespace. Afterwards the checks are identical to non-idmapped mounts. This has no effect for e.g. security xattrs since they don't store uids or gids and don't perform permission checks on them like posix acls do. Link: https://lore.kernel.org/r/20210121131959.646623-10-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Tycho Andersen <tycho@tycho.pizza> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-24inode: make init and permission helpers idmapped mount awareChristian Brauner
The inode_owner_or_capable() helper determines whether the caller is the owner of the inode or is capable with respect to that inode. Allow it to handle idmapped mounts. If the inode is accessed through an idmapped mount it according to the mount's user namespace. Afterwards the checks are identical to non-idmapped mounts. If the initial user namespace is passed nothing changes so non-idmapped mounts will see identical behavior as before. Similarly, allow the inode_init_owner() helper to handle idmapped mounts. It initializes a new inode on idmapped mounts by mapping the fsuid and fsgid of the caller from the mount's user namespace. If the initial user namespace is passed nothing changes so non-idmapped mounts will see identical behavior as before. Link: https://lore.kernel.org/r/20210121131959.646623-7-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-14selinux: include a consumer of the new IMA critical data hookLakshmi Ramasubramanian
SELinux stores the active policy in memory, so the changes to this data at runtime would have an impact on the security guarantees provided by SELinux. Measuring in-memory SELinux policy through IMA subsystem provides a secure way for the attestation service to remotely validate the policy contents at runtime. Measure the hash of the loaded policy by calling the IMA hook ima_measure_critical_data(). Since the size of the loaded policy can be large (several MB), measure the hash of the policy instead of the entire policy to avoid bloating the IMA log entry. To enable SELinux data measurement, the following steps are required: 1, Add "ima_policy=critical_data" to the kernel command line arguments to enable measuring SELinux data at boot time. For example, BOOT_IMAGE=/boot/vmlinuz-5.10.0-rc1+ root=UUID=fd643309-a5d2-4ed3-b10d-3c579a5fab2f ro nomodeset security=selinux ima_policy=critical_data 2, Add the following rule to /etc/ima/ima-policy measure func=CRITICAL_DATA label=selinux Sample measurement of the hash of SELinux policy: To verify the measured data with the current SELinux policy run the following commands and verify the output hash values match. sha256sum /sys/fs/selinux/policy | cut -d' ' -f 1 grep "selinux-policy-hash" /sys/kernel/security/integrity/ima/ascii_runtime_measurements | tail -1 | cut -d' ' -f 6 Note that the actual verification of SELinux policy would require loading the expected policy into an identical kernel on a pristine/known-safe system and run the sha256sum /sys/kernel/selinux/policy there to get the expected hash. Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com> Suggested-by: Stephen Smalley <stephen.smalley.work@gmail.com> Acked-by: Paul Moore <paul@paul-moore.com> Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2021-01-14selinux: teach SELinux about anonymous inodesDaniel Colascione
This change uses the anon_inodes and LSM infrastructure introduced in the previous patches to give SELinux the ability to control anonymous-inode files that are created using the new anon_inode_getfd_secure() function. A SELinux policy author detects and controls these anonymous inodes by adding a name-based type_transition rule that assigns a new security type to anonymous-inode files created in some domain. The name used for the name-based transition is the name associated with the anonymous inode for file listings --- e.g., "[userfaultfd]" or "[perf_event]". Example: type uffd_t; type_transition sysadm_t sysadm_t : anon_inode uffd_t "[userfaultfd]"; allow sysadm_t uffd_t:anon_inode { create }; (The next patch in this series is necessary for making userfaultfd support this new interface. The example above is just for exposition.) Signed-off-by: Daniel Colascione <dancol@google.com> Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-01-13selinux: fall back to SECURITY_FS_USE_GENFS if no xattr supportOndrej Mosnacek
When a superblock is assigned the SECURITY_FS_USE_XATTR behavior by the policy yet it lacks xattr support, try to fall back to genfs rather than rejecting the mount. If a genfscon rule is found for the filesystem, then change the behavior to SECURITY_FS_USE_GENFS, otherwise reject the mount as before. A similar fallback is already done in security_fs_use() if no behavior specification is found for the given filesystem. This is needed e.g. for virtiofs, which may or may not support xattrs depending on the backing host filesystem. Example: # seinfo --genfs | grep ' ramfs' genfscon ramfs / system_u:object_r:ramfs_t:s0 # echo '(fsuse xattr ramfs (system_u object_r fs_t ((s0) (s0))))' >ramfs_xattr.cil # semodule -i ramfs_xattr.cil # mount -t ramfs none /mnt Before: mount: /mnt: mount(2) system call failed: Operation not supported. After: (mount succeeds) # ls -Zd /mnt system_u:object_r:ramfs_t:s0 /mnt See also: https://lore.kernel.org/selinux/20210105142148.GA3200@redhat.com/T/ https://github.com/fedora-selinux/selinux-policy/pull/478 Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-01-12selinux: mark selinux_xfrm_refcount as __read_mostlyOndrej Mosnacek
This is motivated by a perfomance regression of selinux_xfrm_enabled() that happened on a RHEL kernel due to false sharing between selinux_xfrm_refcount and (the late) selinux_ss.policy_rwlock (i.e. the .bss section memory layout changed such that they happened to share the same cacheline). Since the policy rwlock's memory region was modified upon each read-side critical section, the readers of selinux_xfrm_refcount had frequent cache misses, eventually leading to a significant performance degradation under a TCP SYN flood on a system with many cores (32 in this case, but it's detectable on less cores as well). While upstream has since switched to RCU locking, so the same can no longer happen here, selinux_xfrm_refcount could still share a cacheline with another frequently written region, thus marking it __read_mostly still makes sense. __read_mostly helps, because it will put the symbol in a separate section along with other read-mostly variables, so there should never be a clash with frequently written data. Since selinux_xfrm_refcount is modified only in case of an explicit action, it should be safe to do this (i.e. it shouldn't disrupt other read-mostly variables too much). Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-01-12selinux: mark some global variables __ro_after_initOndrej Mosnacek
All of these are never modified outside initcalls, so they can be __ro_after_init. Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-01-12selinux: make selinuxfs_mount staticOndrej Mosnacek
It is not referenced outside selinuxfs.c, so remove its extern header declaration and make it static. Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-01-12selinux: drop the unnecessary aurule_callback variableOndrej Mosnacek
Its value is actually not changed anywhere, so it can be substituted for a direct call to audit_update_lsm_rules(). Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-01-12selinux: remove unused global variablesOndrej Mosnacek
All of sel_ib_pkey_list, sel_netif_list, sel_netnode_list, and sel_netport_list are declared but never used. Remove them. Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-01-04selinux: fix inconsistency between inode_getxattr and inode_listsecurityAmir Goldstein
When inode has no listxattr op of its own (e.g. squashfs) vfs_listxattr calls the LSM inode_listsecurity hooks to list the xattrs that LSMs will intercept in inode_getxattr hooks. When selinux LSM is installed but not initialized, it will list the security.selinux xattr in inode_listsecurity, but will not intercept it in inode_getxattr. This results in -ENODATA for a getxattr call for an xattr returned by listxattr. This situation was manifested as overlayfs failure to copy up lower files from squashfs when selinux is built-in but not initialized, because ovl_copy_xattr() iterates the lower inode xattrs by vfs_listxattr() and vfs_getxattr(). Match the logic of inode_listsecurity to that of inode_getxattr and do not list the security.selinux xattr if selinux is not initialized. Reported-by: Michael Labriola <michael.d.labriola@gmail.com> Tested-by: Michael Labriola <michael.d.labriola@gmail.com> Link: https://lore.kernel.org/linux-unionfs/2nv9d47zt7.fsf@aldarion.sourceruckus.org/ Fixes: c8e222616c7e ("selinux: allow reading labels before policy is loaded") Cc: stable@vger.kernel.org#v5.9+ Signed-off-by: Amir Goldstein <amir73il@gmail.com> Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-01-04selinux: handle MPTCP consistently with TCPPaolo Abeni
The MPTCP protocol uses a specific protocol value, even if it's an extension to TCP. Additionally, MPTCP sockets could 'fall-back' to TCP at run-time, depending on peer MPTCP support and available resources. As a consequence of the specific protocol number, selinux applies the raw_socket class to MPTCP sockets. Existing TCP application converted to MPTCP - or forced to use MPTCP socket with user-space hacks - will need an updated policy to run successfully. This change lets selinux attach the TCP socket class to MPTCP sockets, too, so that no policy changes are needed in the above scenario. Note that the MPTCP is setting, propagating and updating the security context on all the subflows and related request socket. Link: https://lore.kernel.org/linux-security-module/CAHC9VhTaK3xx0hEGByD2zxfF7fadyPP1kb-WeWH_YCyq9X-sRg@mail.gmail.com/T/#t Signed-off-by: Paolo Abeni <pabeni@redhat.com> [PM: tweaked subject's prefix] Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-12-16Merge tag 'selinux-pr-20201214' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux Pull selinux updates from Paul Moore: "While we have a small number of SELinux patches for v5.11, there are a few changes worth highlighting: - Change the LSM network hooks to pass flowi_common structs instead of the parent flowi struct as the LSMs do not currently need the full flowi struct and they do not have enough information to use it safely (missing information on the address family). This patch was discussed both with Herbert Xu (representing team netdev) and James Morris (representing team LSMs-other-than-SELinux). - Fix how we handle errors in inode_doinit_with_dentry() so that we attempt to properly label the inode on following lookups instead of continuing to treat it as unlabeled. - Tweak the kernel logic around allowx, auditallowx, and dontauditx SELinux policy statements such that the auditx/dontauditx are effective even without the allowx statement. Everything passes our test suite" * tag 'selinux-pr-20201214' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux: lsm,selinux: pass flowi_common instead of flowi to the LSM hooks selinux: Fix fall-through warnings for Clang selinux: drop super_block backpointer from superblock_security_struct selinux: fix inode_doinit_with_dentry() LABEL_INVALID error handling selinux: allow dontauditx and auditallowx rules to take effect without allowx selinux: fix error initialization in inode_doinit_with_dentry()
2020-12-03security: add const qualifier to struct sock in various placesFlorian Westphal
A followup change to tcp_request_sock_op would have to drop the 'const' qualifier from the 'route_req' function as the 'security_inet_conn_request' call is moved there - and that function expects a 'struct sock *'. However, it turns out its also possible to add a const qualifier to security_inet_conn_request instead. Signed-off-by: Florian Westphal <fw@strlen.de> Acked-by: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2020-11-23lsm,selinux: pass flowi_common instead of flowi to the LSM hooksPaul Moore
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 <herbert@gondor.apana.org.au> Acked-by: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-11-23selinux: Fix fall-through warnings for ClangGustavo A. R. Silva
In preparation to enable -Wimplicit-fallthrough for Clang, fix a warning by explicitly adding a break statement instead of letting the code fall through to the next case. Link: https://github.com/KSPP/linux/issues/115 Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-11-14Merge tag 'selinux-pr-20201113' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux Pull selinux fix from Paul Moore: "One small SELinux patch to make sure we return an error code when an allocation fails. It passes all of our tests, but given the nature of the patch that isn't surprising" * tag 'selinux-pr-20201113' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux: selinux: Fix error return code in sel_ib_pkey_sid_slow()
2020-11-12selinux: Fix error return code in sel_ib_pkey_sid_slow()Chen Zhou
Fix to return a negative error code from the error handling case instead of 0 in function sel_ib_pkey_sid_slow(), as done elsewhere in this function. Cc: stable@vger.kernel.org Fixes: 409dcf31538a ("selinux: Add a cache for quicker retreival of PKey SIDs") Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Chen Zhou <chenzhou10@huawei.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-11-12selinux: drop super_block backpointer from superblock_security_structOndrej Mosnacek
It appears to have been needed for selinux_complete_init() in the past, but today it's useless. Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-11-05selinux: fix inode_doinit_with_dentry() LABEL_INVALID error handlingPaul Moore
A previous fix, commit 83370b31a915 ("selinux: fix error initialization in inode_doinit_with_dentry()"), changed how failures were handled before a SELinux policy was loaded. Unfortunately that patch was potentially problematic for two reasons: it set the isec->initialized state without holding a lock, and it didn't set the inode's SELinux label to the "default" for the particular filesystem. The later can be a problem if/when a later attempt to revalidate the inode fails and SELinux reverts to the existing inode label. This patch should restore the default inode labeling that existed before the original fix, without affecting the LABEL_INVALID marking such that revalidation will still be attempted in the future. Fixes: 83370b31a915 ("selinux: fix error initialization in inode_doinit_with_dentry()") Reported-by: Sven Schnelle <svens@linux.ibm.com> Tested-by: Sven Schnelle <svens@linux.ibm.com> Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-10-27selinux: allow dontauditx and auditallowx rules to take effect without allowxbauen1
This allows for dontauditing very specific ioctls e.g. TCGETS without dontauditing every ioctl or granting additional permissions. Now either an allowx, dontauditx or auditallowx rules enables checking for extended permissions. Signed-off-by: Jonathan Hettwer <j2468h@gmail.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-10-27selinux: fix error initialization in inode_doinit_with_dentry()Tianyue Ren
Mark the inode security label as invalid if we cannot find a dentry so that we will retry later rather than marking it initialized with the unlabeled SID. Fixes: 9287aed2ad1f ("selinux: Convert isec->lock into a spinlock") Signed-off-by: Tianyue Ren <rentianyue@kylinos.cn> [PM: minor comment tweaks] Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-10-15Merge tag 'char-misc-5.10-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc Pull char/misc driver updates from Greg KH: "Here is the big set of char, misc, and other assorted driver subsystem patches for 5.10-rc1. There's a lot of different things in here, all over the drivers/ directory. Some summaries: - soundwire driver updates - habanalabs driver updates - extcon driver updates - nitro_enclaves new driver - fsl-mc driver and core updates - mhi core and bus updates - nvmem driver updates - eeprom driver updates - binder driver updates and fixes - vbox minor bugfixes - fsi driver updates - w1 driver updates - coresight driver updates - interconnect driver updates - misc driver updates - other minor driver updates All of these have been in linux-next for a while with no reported issues" * tag 'char-misc-5.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (396 commits) binder: fix UAF when releasing todo list docs: w1: w1_therm: Fix broken xref, mistakes, clarify text misc: Kconfig: fix a HISI_HIKEY_USB dependency LSM: Fix type of id parameter in kernel_post_load_data prototype misc: Kconfig: add a new dependency for HISI_HIKEY_USB firmware_loader: fix a kernel-doc markup w1: w1_therm: make w1_poll_completion static binder: simplify the return expression of binder_mmap test_firmware: Test partial read support firmware: Add request_partial_firmware_into_buf() firmware: Store opt_flags in fw_priv fs/kernel_file_read: Add "offset" arg for partial reads IMA: Add support for file reads without contents LSM: Add "contents" flag to kernel_read_file hook module: Call security_kernel_post_load_data() firmware_loader: Use security_post_load_data() LSM: Introduce kernel_post_load_data() hook fs/kernel_read_file: Add file_size output argument fs/kernel_read_file: Switch buffer size arg to size_t fs/kernel_read_file: Remove redundant size argument ...
2020-10-13Merge tag 'selinux-pr-20201012' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux Pull selinux updates from Paul Moore: "A decent number of SELinux patches for v5.10, twenty two in total. The highlights are listed below, but all of the patches pass our test suite and merge cleanly. - A number of changes to how the SELinux policy is loaded and managed inside the kernel with the goal of improving the atomicity of a SELinux policy load operation. These changes account for the bulk of the diffstat as well as the patch count. A special thanks to everyone who contributed patches and fixes for this work. - Convert the SELinux policy read-write lock to RCU. - A tracepoint was added for audited SELinux access control events; this should help provide a more unified backtrace across kernel and userspace. - Allow the removal of security.selinux xattrs when a SELinux policy is not loaded. - Enable policy capabilities in SELinux policies created with the scripts/selinux/mdp tool. - Provide some "no sooner than" dates for the SELinux checkreqprot sysfs deprecation" * tag 'selinux-pr-20201012' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux: (22 commits) selinux: provide a "no sooner than" date for the checkreqprot removal selinux: Add helper functions to get and set checkreqprot selinux: access policycaps with READ_ONCE/WRITE_ONCE selinux: simplify away security_policydb_len() selinux: move policy mutex to selinux_state, use in lockdep checks selinux: fix error handling bugs in security_load_policy() selinux: convert policy read-write lock to RCU selinux: delete repeated words in comments selinux: add basic filtering for audit trace events selinux: add tracepoint on audited events selinux: Create new booleans and class dirs out of tree selinux: Standardize string literal usage for selinuxfs directory names selinux: Refactor selinuxfs directory populating functions selinux: Create function for selinuxfs directory cleanup selinux: permit removing security.selinux xattr before policy load selinux: fix memdup.cocci warnings selinux: avoid dereferencing the policy prior to initialization selinux: fix allocation failure check on newpolicy->sidtab selinux: refactor changing booleans selinux: move policy commit after updating selinuxfs ...
2020-10-05LSM: Add "contents" flag to kernel_read_file hookKees Cook
As with the kernel_load_data LSM hook, add a "contents" flag to the kernel_read_file LSM hook that indicates whether the LSM can expect a matching call to the kernel_post_read_file LSM hook with the full contents of the file. With the coming addition of partial file read support for kernel_read_file*() API, the LSM will no longer be able to always see the entire contents of a file during the read calls. For cases where the LSM must read examine the complete file contents, it will need to do so on its own every time the kernel_read_file hook is called with contents=false (or reject such cases). Adjust all existing LSMs to retain existing behavior. Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> Link: https://lore.kernel.org/r/20201002173828.2099543-12-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-05LSM: Introduce kernel_post_load_data() hookKees Cook
There are a few places in the kernel where LSMs would like to have visibility into the contents of a kernel buffer that has been loaded or read. While security_kernel_post_read_file() (which includes the buffer) exists as a pairing for security_kernel_read_file(), no such hook exists to pair with security_kernel_load_data(). Earlier proposals for just using security_kernel_post_read_file() with a NULL file argument were rejected (i.e. "file" should always be valid for the security_..._file hooks, but it appears at least one case was left in the kernel during earlier refactoring. (This will be fixed in a subsequent patch.) Since not all cases of security_kernel_load_data() can have a single contiguous buffer made available to the LSM hook (e.g. kexec image segments are separately loaded), there needs to be a way for the LSM to reason about its expectations of the hook coverage. In order to handle this, add a "contents" argument to the "kernel_load_data" hook that indicates if the newly added "kernel_post_load_data" hook will be called with the full contents once loaded. That way, LSMs requiring full contents can choose to unilaterally reject "kernel_load_data" with contents=false (which is effectively the existing hook coverage), but when contents=true they can allow it and later evaluate the "kernel_post_load_data" hook once the buffer is loaded. With this change, LSMs can gain coverage over non-file-backed data loads (e.g. init_module(2) and firmware userspace helper), which will happen in subsequent patches. Additionally prepare IMA to start processing these cases. Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: KP Singh <kpsingh@google.com> Link: https://lore.kernel.org/r/20201002173828.2099543-9-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-05fs/kernel_read_file: Split into separate include fileScott Branden
Move kernel_read_file* out of linux/fs.h to its own linux/kernel_read_file.h include file. That header gets pulled in just about everywhere and doesn't really need functions not related to the general fs interface. Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Scott Branden <scott.branden@broadcom.com> Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: James Morris <jamorris@linux.microsoft.com> Link: https://lore.kernel.org/r/20200706232309.12010-2-scott.branden@broadcom.com Link: https://lore.kernel.org/r/20201002173828.2099543-4-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-09-15selinux: Add helper functions to get and set checkreqprotLakshmi Ramasubramanian
checkreqprot data member in selinux_state struct is accessed directly by SELinux functions to get and set. This could cause unexpected read or write access to this data member due to compiler optimizations and/or compiler's reordering of access to this field. Add helper functions to get and set checkreqprot data member in selinux_state struct. These helper functions use READ_ONCE and WRITE_ONCE macros to ensure atomic read or write of memory for this data member. Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com> Suggested-by: Stephen Smalley <stephen.smalley.work@gmail.com> Suggested-by: Paul Moore <paul@paul-moore.com> Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-09-11selinux: access policycaps with READ_ONCE/WRITE_ONCEStephen Smalley
Use READ_ONCE/WRITE_ONCE for all accesses to the selinux_state.policycaps booleans to prevent compiler mischief. Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-31selinux: simplify away security_policydb_len()Ondrej Mosnacek
Remove the security_policydb_len() calls from sel_open_policy() and instead update the inode size from the size returned from security_read_policy(). Since after this change security_policydb_len() is only called from security_load_policy(), remove it entirely and just open-code it there. Also, since security_load_policy() is always called with policy_mutex held, make it dereference the policy pointer directly and drop the unnecessary RCU locking. Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-27selinux: move policy mutex to selinux_state, use in lockdep checksStephen Smalley
Move the mutex used to synchronize policy changes (reloads and setting of booleans) from selinux_fs_info to selinux_state and use it in lockdep checks for rcu_dereference_protected() calls in the security server functions. This makes the dependency on the mutex explicit in the code rather than relying on comments. Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com> Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-26selinux: fix error handling bugs in security_load_policy()Dan Carpenter
There are a few bugs in the error handling for security_load_policy(). 1) If the newpolicy->sidtab allocation fails then it leads to a NULL dereference. Also the error code was not set to -ENOMEM on that path. 2) If policydb_read() failed then we call policydb_destroy() twice which meands we call kvfree(p->sym_val_to_name[i]) twice. 3) If policydb_load_isids() failed then we call sidtab_destroy() twice and that results in a double free in the sidtab_destroy_tree() function because entry.ptr_inner and entry.ptr_leaf are not set to NULL. One thing that makes this code nice to deal with is that none of the functions return partially allocated data. In other words, the policydb_read() either allocates everything successfully or it frees all the data it allocates. It never returns a mix of allocated and not allocated data. I re-wrote this to only free the successfully allocated data which avoids the double frees. I also re-ordered selinux_policy_free() so it's in the reverse order of the allocation function. Fixes: c7c556f1e81b ("selinux: refactor changing booleans") Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> [PM: partially merged by hand due to merge fuzz] Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-25selinux: convert policy read-write lock to RCUStephen Smalley
Convert the policy read-write lock to RCU. This is significantly simplified by the earlier work to encapsulate the policy data structures and refactor the policy load and boolean setting logic. Move the latest_granting sequence number into the selinux_policy structure so that it can be updated atomically with the policy. Since removing the policy rwlock and moving latest_granting reduces the selinux_ss structure to nothing more than a wrapper around the selinux_policy pointer, get rid of the extra layer of indirection. At present this change merely passes a hardcoded 1 to rcu_dereference_check() in the cases where we know we do not need to take rcu_read_lock(), with the preceding comment explaining why. Alternatively we could pass fsi->mutex down from selinuxfs and apply a lockdep check on it instead. Based in part on earlier attempts to convert the policy rwlock to RCU by Kaigai Kohei [1] and by Peter Enderborg [2]. [1] https://lore.kernel.org/selinux/6e2f9128-e191-ebb3-0e87-74bfccb0767f@tycho.nsa.gov/ [2] https://lore.kernel.org/selinux/20180530141104.28569-1-peter.enderborg@sony.com/ Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com> Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-24selinux: delete repeated words in commentsRandy Dunlap
Drop a repeated word in comments. {open, is, then} Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Paul Moore <paul@paul-moore.com> Cc: Stephen Smalley <stephen.smalley.work@gmail.com> Cc: Eric Paris <eparis@parisplace.org> Cc: selinux@vger.kernel.org Cc: James Morris <jmorris@namei.org> Cc: "Serge E. Hallyn" <serge@hallyn.com> Cc: linux-security-module@vger.kernel.org [PM: fix subject line] Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-23treewide: Use fallthrough pseudo-keywordGustavo A. R. Silva
Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-08-21selinux: add basic filtering for audit trace eventsPeter Enderborg
This patch adds further attributes to the event. These attributes are helpful to understand the context of the message and can be used to filter the events. There are three common items. Source context, target context and tclass. There are also items from the outcome of operation performed. An event is similar to: <...>-1309 [002] .... 6346.691689: selinux_audited: requested=0x4000000 denied=0x4000000 audited=0x4000000 result=-13 scontext=system_u:system_r:cupsd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:bin_t:s0 tclass=file With systems where many denials are occurring, it is useful to apply a filter. The filtering is a set of logic that is inserted with the filter file. Example: echo "tclass==\"file\" " > events/avc/selinux_audited/filter This adds that we only get tclass=file. The trace can also have extra properties. Adding the user stack can be done with echo 1 > options/userstacktrace Now the output will be runcon-1365 [003] .... 6960.955530: selinux_audited: requested=0x4000000 denied=0x4000000 audited=0x4000000 result=-13 scontext=system_u:system_r:cupsd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:bin_t:s0 tclass=file runcon-1365 [003] .... 6960.955560: <user stack trace> => <00007f325b4ce45b> => <00005607093efa57> Signed-off-by: Peter Enderborg <peter.enderborg@sony.com> Reviewed-by: Thiébaud Weksteen <tweek@google.com> Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-21selinux: add tracepoint on audited eventsThiébaud Weksteen
The audit data currently captures which process and which target is responsible for a denial. There is no data on where exactly in the process that call occurred. Debugging can be made easier by being able to reconstruct the unified kernel and userland stack traces [1]. Add a tracepoint on the SELinux denials which can then be used by userland (i.e. perf). Although this patch could manually be added by each OS developer to trouble shoot a denial, adding it to the kernel streamlines the developers workflow. It is possible to use perf for monitoring the event: # perf record -e avc:selinux_audited -g -a ^C # perf report -g [...] 6.40% 6.40% audited=800000 tclass=4 | __libc_start_main | |--4.60%--__GI___ioctl | entry_SYSCALL_64 | do_syscall_64 | __x64_sys_ioctl | ksys_ioctl | binder_ioctl | binder_set_nice | can_nice | capable | security_capable | cred_has_capability.isra.0 | slow_avc_audit | common_lsm_audit | avc_audit_post_callback | avc_audit_post_callback | It is also possible to use the ftrace interface: # echo 1 > /sys/kernel/debug/tracing/events/avc/selinux_audited/enable # cat /sys/kernel/debug/tracing/trace tracer: nop entries-in-buffer/entries-written: 1/1 #P:8 [...] dmesg-3624 [001] 13072.325358: selinux_denied: audited=800000 tclass=4 The tclass value can be mapped to a class by searching security/selinux/flask.h. The audited value is a bit field of the permissions described in security/selinux/av_permissions.h for the corresponding class. [1] https://source.android.com/devices/tech/debug/native_stack_dump Signed-off-by: Thiébaud Weksteen <tweek@google.com> Suggested-by: Joel Fernandes <joelaf@google.com> Reviewed-by: Peter Enderborg <peter.enderborg@sony.com> Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-21selinux: Create new booleans and class dirs out of treeDaniel Burgener
In order to avoid concurrency issues around selinuxfs resource availability during policy load, we first create new directories out of tree for reloaded resources, then swap them in, and finally delete the old versions. This fix focuses on concurrency in each of the two subtrees swapped, and not concurrency between the trees. This means that it is still possible that subsequent reads to eg the booleans directory and the class directory during a policy load could see the old state for one and the new for the other. The problem of ensuring that policy loads are fully atomic from the perspective of userspace is larger than what is dealt with here. This commit focuses on ensuring that the directories contents always match either the new or the old policy state from the perspective of userspace. In the previous implementation, on policy load /sys/fs/selinux is updated by deleting the previous contents of /sys/fs/selinux/{class,booleans} and then recreating them. This means that there is a period of time when the contents of these directories do not exist which can cause race conditions as userspace relies on them for information about the policy. In addition, it means that error recovery in the event of failure is challenging. In order to demonstrate the race condition that this series fixes, you can use the following commands: while true; do cat /sys/fs/selinux/class/service/perms/status >/dev/null; done & while true; do load_policy; done; In the existing code, this will display errors fairly often as the class lookup fails. (In normal operation from systemd, this would result in a permission check which would be allowed or denied based on policy settings around unknown object classes.) After applying this patch series you should expect to no longer see such error messages. Signed-off-by: Daniel Burgener <dburgener@linux.microsoft.com> Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com> Signed-off-by: Paul Moore <paul@paul-moore.com>