kernel.git/security/integrity/evm/evm_crypto.c, branch linux-6.2.y

lsm,fs: fix vfs_getxattr_alloc() return type and caller error paths

2022-11-18T22:07:03Z

The vfs_getxattr_alloc() function currently returns a ssize_t value despite the fact that it only uses int values internally for return values. Fix this by converting vfs_getxattr_alloc() to return an int type and adjust the callers as necessary. As part of these caller modifications, some of the callers are fixed to properly free the xattr value buffer on both success and failure to ensure that memory is not leaked in the failure case. Reviewed-by: Serge Hallyn Reviewed-by: Mimi Zohar Signed-off-by: Paul Moore

Revert "evm: Fix memleak in init_desc"

2022-06-15T18:03:47Z

This reverts commit ccf11dbaa07b328fa469415c362d33459c140a37. Commit ccf11dbaa07b ("evm: Fix memleak in init_desc") said there is memleak in init_desc. That may be incorrect, as we can see, tmp_tfm is saved in one of the two global variables hmac_tfm or evm_tfm[hash_algo], then if init_desc is called next time, there is no need to alloc tfm again, so in the error path of kmalloc desc or crypto_shash_init(desc), It is not a problem without freeing tmp_tfm. And also that commit did not reset the global variable to NULL after freeing tmp_tfm and this makes *tfm a dangling pointer which may cause a UAF issue. Reported-by: Guozihua (Scott) Signed-off-by: Xiu Jianfeng Signed-off-by: Mimi Zohar

evm: Clean up some variables

2022-05-16T12:14:38Z

Make hmac_tfm static since it's not used anywhere else besides the file it is in. Remove declaration of hash_tfm since it doesn't exist. Signed-off-by: Stefan Berger Signed-off-by: Mimi Zohar

evm: Check xattr size discrepancy between kernel and user

2021-06-21T12:34:21Z

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 Suggested-by: Mimi Zohar Signed-off-by: Mimi Zohar

evm: output EVM digest calculation info

2021-06-20T15:10:25Z

Output the data used in calculating the EVM digest and the resulting digest as ascii hexadecimal strings. Suggested-by: Lakshmi Ramasubramanian (CONFIG_DYNAMIC_DEBUG) Reviewed-by: Lakshmi Ramasubramanian Reported-by: kernel test robot (Use %zu for size_t) Signed-off-by: Mimi Zohar

evm: Verify portable signatures against all protected xattrs

2021-06-01T19:17:31Z

Currently, the evm_config_default_xattrnames array contains xattr names only related to LSMs which are enabled in the kernel configuration. However, EVM portable signatures do not depend on local information and a vendor might include in the signature calculation xattrs that are not enabled in the target platform. Just including all xattrs names in evm_config_default_xattrnames is not a safe approach, because a target system might have already calculated signatures or HMACs based only on the enabled xattrs. After applying this patch, EVM would verify those signatures and HMACs with all xattrs instead. The non-enabled ones, which could possibly exist, would cause a verification error. Thus, this patch adds a new field named enabled to the xattr_list structure, which is set to true if the LSM associated to a given xattr name is enabled in the kernel configuration. The non-enabled xattrs are taken into account only in evm_calc_hmac_or_hash(), if the passed security.evm type is EVM_XATTR_PORTABLE_DIGSIG. The new function evm_protected_xattr_if_enabled() has been defined so that IMA can include all protected xattrs and not only the enabled ones in the measurement list, if the new template fields xattrnames, xattrlengths or xattrvalues have been included in the template format. Signed-off-by: Roberto Sassu Signed-off-by: Mimi Zohar

Merge tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

2021-02-23T21:39:45Z

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 ...

xattr: handle idmapped mounts

2021-01-24T13:27:17Z

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 Cc: David Howells Cc: Al Viro Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig Reviewed-by: James Morris Signed-off-by: Tycho Andersen Signed-off-by: Christian Brauner

evm: Fix memleak in init_desc

2021-01-13T12:22:12Z

tmp_tfm is allocated, but not freed on subsequent kmalloc failure, which leads to a memory leak. Free tmp_tfm. Fixes: d46eb3699502b ("evm: crypto hash replaced by shash") Signed-off-by: Dinghao Liu [zohar@linux.ibm.com: formatted/reworded patch description] Signed-off-by: Mimi Zohar

Merge tag 'integrity-v5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

2020-06-06T16:39:05Z

Pull integrity updates from Mimi Zohar: "The main changes are extending the TPM 2.0 PCR banks with bank specific file hashes, calculating the "boot_aggregate" based on other TPM PCR banks, using the default IMA hash algorithm, instead of SHA1, as the basis for the cache hash table key, and preventing the mprotect syscall to circumvent an IMA mmap appraise policy rule. - In preparation for extending TPM 2.0 PCR banks with bank specific digests, commit 0b6cf6b97b7e ("tpm: pass an array of tpm_extend_digest structures to tpm_pcr_extend()") modified tpm_pcr_extend(). The original SHA1 file digests were padded/truncated, before being extended into the other TPM PCR banks. This pull request calculates and extends the TPM PCR banks with bank specific file hashes completing the above change. - The "boot_aggregate", the first IMA measurement list record, is the "trusted boot" link between the pre-boot environment and the running OS. With TPM 2.0, the "boot_aggregate" record is not limited to being based on the SHA1 TPM PCR bank, but can be calculated based on any enabled bank, assuming the hash algorithm is also enabled in the kernel. Other changes include the following and five other bug fixes/code clean up: - supporting both a SHA1 and a larger "boot_aggregate" digest in a custom template format containing both the the SHA1 ('d') and larger digests ('d-ng') fields. - Initial hash table key fix, but additional changes would be good" * tag 'integrity-v5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity: ima: Directly free *entry in ima_alloc_init_template() if digests is NULL ima: Call ima_calc_boot_aggregate() in ima_eventdigest_init() ima: Directly assign the ima_default_policy pointer to ima_rules ima: verify mprotect change is consistent with mmap policy evm: Fix possible memory leak in evm_calc_hmac_or_hash() ima: Set again build_ima_appraise variable ima: Remove redundant policy rule set in add_rules() ima: Fix ima digest hash table key calculation ima: Use ima_hash_algo for collision detection in the measurement list ima: Calculate and extend PCR with digests in ima_template_entry ima: Allocate and initialize tfm for each PCR bank ima: Switch to dynamically allocated buffer for template digests ima: Store template digest directly in ima_template_entry ima: Evaluate error in init_ima() ima: Switch to ima_hash_algo for boot aggregate