1. 24 11月, 2020 1 次提交
  2. 26 10月, 2020 1 次提交
  3. 05 10月, 2020 2 次提交
    • K
      LSM: Add "contents" flag to kernel_read_file hook · 2039bda1
      Kees Cook 提交于
      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: NKees Cook <keescook@chromium.org>
      Reviewed-by: NMimi Zohar <zohar@linux.ibm.com>
      Link: https://lore.kernel.org/r/20201002173828.2099543-12-keescook@chromium.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      2039bda1
    • K
      LSM: Introduce kernel_post_load_data() hook · b64fcae7
      Kees Cook 提交于
      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: NKees Cook <keescook@chromium.org>
      Reviewed-by: NKP Singh <kpsingh@google.com>
      Link: https://lore.kernel.org/r/20201002173828.2099543-9-keescook@chromium.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b64fcae7
  4. 07 8月, 2020 1 次提交
  5. 15 6月, 2020 1 次提交
  6. 30 5月, 2020 2 次提交
    • E
      exec: Compute file based creds only once · 56305aa9
      Eric W. Biederman 提交于
      Move the computation of creds from prepare_binfmt into begin_new_exec
      so that the creds need only be computed once.  This is just code
      reorganization no semantic changes of any kind are made.
      
      Moving the computation is safe.  I have looked through the kernel and
      verified none of the binfmts look at bprm->cred directly, and that
      there are no helpers that look at bprm->cred indirectly.  Which means
      that it is not a problem to compute the bprm->cred later in the
      execution flow as it is not used until it becomes current->cred.
      
      A new function bprm_creds_from_file is added to contain the work that
      needs to be done.  bprm_creds_from_file first computes which file
      bprm->executable or most likely bprm->file that the bprm->creds
      will be computed from.
      
      The funciton bprm_fill_uid is updated to receive the file instead of
      accessing bprm->file.  The now unnecessary work needed to reset the
      bprm->cred->euid, and bprm->cred->egid is removed from brpm_fill_uid.
      A small comment to document that bprm_fill_uid now only deals with the
      work to handle suid and sgid files.  The default case is already
      heandled by prepare_exec_creds.
      
      The function security_bprm_repopulate_creds is renamed
      security_bprm_creds_from_file and now is explicitly passed the file
      from which to compute the creds.  The documentation of the
      bprm_creds_from_file security hook is updated to explain when the hook
      is called and what it needs to do.  The file is passed from
      cap_bprm_creds_from_file into get_file_caps so that the caps are
      computed for the appropriate file.  The now unnecessary work in
      cap_bprm_creds_from_file to reset the ambient capabilites has been
      removed.  A small comment to document that the work of
      cap_bprm_creds_from_file is to read capabilities from the files
      secureity attribute and derive capabilities from the fact the
      user had uid 0 has been added.
      Reviewed-by: NKees Cook <keescook@chromium.org>
      Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
      56305aa9
    • E
      exec: Add a per bprm->file version of per_clear · a7868323
      Eric W. Biederman 提交于
      There is a small bug in the code that recomputes parts of bprm->cred
      for every bprm->file.  The code never recomputes the part of
      clear_dangerous_personality_flags it is responsible for.
      
      Which means that in practice if someone creates a sgid script
      the interpreter will not be able to use any of:
      	READ_IMPLIES_EXEC
      	ADDR_NO_RANDOMIZE
      	ADDR_COMPAT_LAYOUT
      	MMAP_PAGE_ZERO.
      
      This accentially clearing of personality flags probably does
      not matter in practice because no one has complained
      but it does make the code more difficult to understand.
      
      Further remaining bug compatible prevents the recomputation from being
      removed and replaced by simply computing bprm->cred once from the
      final bprm->file.
      
      Making this change removes the last behavior difference between
      computing bprm->creds from the final file and recomputing
      bprm->cred several times.  Which allows this behavior change
      to be justified for it's own reasons, and for any but hunts
      looking into why the behavior changed to wind up here instead
      of in the code that will follow that computes bprm->cred
      from the final bprm->file.
      
      This small logic bug appears to have existed since the code
      started clearing dangerous personality bits.
      
      History Tree: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
      Fixes: 1bb0fa189c6a ("[PATCH] NX: clean up legacy binary support")
      Reviewed-by: NKees Cook <keescook@chromium.org>
      Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
      a7868323
  7. 21 5月, 2020 2 次提交
  8. 19 5月, 2020 2 次提交
  9. 05 5月, 2020 1 次提交
  10. 30 3月, 2020 1 次提交
  11. 20 2月, 2020 1 次提交
    • R
      security: <linux/lsm_hooks.h>: fix all kernel-doc warnings · bd1a5a53
      Randy Dunlap 提交于
      Fix all kernel-doc warnings in <linux/lsm_hooks.h>.
      Fixes the following warnings:
      
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'quotactl' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'quota_on' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'sb_free_mnt_opts' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'sb_eat_lsm_opts' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'sb_kern_mount' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'sb_show_options' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'sb_add_mnt_opt' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'd_instantiate' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'getprocattr' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'setprocattr' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'locked_down' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'perf_event_open' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'perf_event_alloc' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'perf_event_free' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'perf_event_read' not described in 'security_list_options'
      ../include/linux/lsm_hooks.h:1830: warning: Function parameter or member 'perf_event_write' not described in 'security_list_options'
      Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
      Cc: John Johansen <john.johansen@canonical.com>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Micah Morton <mortonm@chromium.org>
      Cc: James Morris <jmorris@namei.org>
      Cc: "Serge E. Hallyn" <serge@hallyn.com>
      Cc: linux-security-module@vger.kernel.org
      Cc: Paul Moore <paul@paul-moore.com>
      Cc: Stephen Smalley <sds@tycho.nsa.gov>
      Cc: Eric Paris <eparis@parisplace.org>
      Cc: Casey Schaufler <casey@schaufler-ca.com>
      Cc: Kentaro Takeda <takedakn@nttdata.co.jp>
      Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
      Acked-by: NCasey Schaufler <casey@schaufler-ca.com>
      Acked-by: NKees Cook <keescook@chromium.org>
      Signed-off-by: NJames Morris <jmorris@namei.org>
      bd1a5a53
  12. 18 10月, 2019 1 次提交
    • J
      perf_event: Add support for LSM and SELinux checks · da97e184
      Joel Fernandes (Google) 提交于
      In current mainline, the degree of access to perf_event_open(2) system
      call depends on the perf_event_paranoid sysctl.  This has a number of
      limitations:
      
      1. The sysctl is only a single value. Many types of accesses are controlled
         based on the single value thus making the control very limited and
         coarse grained.
      2. The sysctl is global, so if the sysctl is changed, then that means
         all processes get access to perf_event_open(2) opening the door to
         security issues.
      
      This patch adds LSM and SELinux access checking which will be used in
      Android to access perf_event_open(2) for the purposes of attaching BPF
      programs to tracepoints, perf profiling and other operations from
      userspace. These operations are intended for production systems.
      
      5 new LSM hooks are added:
      1. perf_event_open: This controls access during the perf_event_open(2)
         syscall itself. The hook is called from all the places that the
         perf_event_paranoid sysctl is checked to keep it consistent with the
         systctl. The hook gets passed a 'type' argument which controls CPU,
         kernel and tracepoint accesses (in this context, CPU, kernel and
         tracepoint have the same semantics as the perf_event_paranoid sysctl).
         Additionally, I added an 'open' type which is similar to
         perf_event_paranoid sysctl == 3 patch carried in Android and several other
         distros but was rejected in mainline [1] in 2016.
      
      2. perf_event_alloc: This allocates a new security object for the event
         which stores the current SID within the event. It will be useful when
         the perf event's FD is passed through IPC to another process which may
         try to read the FD. Appropriate security checks will limit access.
      
      3. perf_event_free: Called when the event is closed.
      
      4. perf_event_read: Called from the read(2) and mmap(2) syscalls for the event.
      
      5. perf_event_write: Called from the ioctl(2) syscalls for the event.
      
      [1] https://lwn.net/Articles/696240/
      
      Since Peter had suggest LSM hooks in 2016 [1], I am adding his
      Suggested-by tag below.
      
      To use this patch, we set the perf_event_paranoid sysctl to -1 and then
      apply selinux checking as appropriate (default deny everything, and then
      add policy rules to give access to domains that need it). In the future
      we can remove the perf_event_paranoid sysctl altogether.
      Suggested-by: NPeter Zijlstra <peterz@infradead.org>
      Co-developed-by: NPeter Zijlstra <peterz@infradead.org>
      Signed-off-by: NJoel Fernandes (Google) <joel@joelfernandes.org>
      Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
      Acked-by: NJames Morris <jmorris@namei.org>
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      Cc: rostedt@goodmis.org
      Cc: Yonghong Song <yhs@fb.com>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Alexei Starovoitov <ast@kernel.org>
      Cc: jeffv@google.com
      Cc: Jiri Olsa <jolsa@redhat.com>
      Cc: Daniel Borkmann <daniel@iogearbox.net>
      Cc: primiano@google.com
      Cc: Song Liu <songliubraving@fb.com>
      Cc: rsavitski@google.com
      Cc: Namhyung Kim <namhyung@kernel.org>
      Cc: Matthew Garrett <matthewgarrett@google.com>
      Link: https://lkml.kernel.org/r/20191014170308.70668-1-joel@joelfernandes.org
      da97e184
  13. 20 8月, 2019 2 次提交
  14. 13 8月, 2019 1 次提交
    • A
      fanotify, inotify, dnotify, security: add security hook for fs notifications · ac5656d8
      Aaron Goidel 提交于
      As of now, setting watches on filesystem objects has, at most, applied a
      check for read access to the inode, and in the case of fanotify, requires
      CAP_SYS_ADMIN. No specific security hook or permission check has been
      provided to control the setting of watches. Using any of inotify, dnotify,
      or fanotify, it is possible to observe, not only write-like operations, but
      even read access to a file. Modeling the watch as being merely a read from
      the file is insufficient for the needs of SELinux. This is due to the fact
      that read access should not necessarily imply access to information about
      when another process reads from a file. Furthermore, fanotify watches grant
      more power to an application in the form of permission events. While
      notification events are solely, unidirectional (i.e. they only pass
      information to the receiving application), permission events are blocking.
      Permission events make a request to the receiving application which will
      then reply with a decision as to whether or not that action may be
      completed. This causes the issue of the watching application having the
      ability to exercise control over the triggering process. Without drawing a
      distinction within the permission check, the ability to read would imply
      the greater ability to control an application. Additionally, mount and
      superblock watches apply to all files within the same mount or superblock.
      Read access to one file should not necessarily imply the ability to watch
      all files accessed within a given mount or superblock.
      
      In order to solve these issues, a new LSM hook is implemented and has been
      placed within the system calls for marking filesystem objects with inotify,
      fanotify, and dnotify watches. These calls to the hook are placed at the
      point at which the target path has been resolved and are provided with the
      path struct, the mask of requested notification events, and the type of
      object on which the mark is being set (inode, superblock, or mount). The
      mask and obj_type have already been translated into common FS_* values
      shared by the entirety of the fs notification infrastructure. The path
      struct is passed rather than just the inode so that the mount is available,
      particularly for mount watches. This also allows for use of the hook by
      pathname-based security modules. However, since the hook is intended for
      use even by inode based security modules, it is not placed under the
      CONFIG_SECURITY_PATH conditional. Otherwise, the inode-based security
      modules would need to enable all of the path hooks, even though they do not
      use any of them.
      
      This only provides a hook at the point of setting a watch, and presumes
      that permission to set a particular watch implies the ability to receive
      all notification about that object which match the mask. This is all that
      is required for SELinux. If other security modules require additional hooks
      or infrastructure to control delivery of notification, these can be added
      by them. It does not make sense for us to propose hooks for which we have
      no implementation. The understanding that all notifications received by the
      requesting application are all strictly of a type for which the application
      has been granted permission shows that this implementation is sufficient in
      its coverage.
      
      Security modules wishing to provide complete control over fanotify must
      also implement a security_file_open hook that validates that the access
      requested by the watching application is authorized. Fanotify has the issue
      that it returns a file descriptor with the file mode specified during
      fanotify_init() to the watching process on event. This is already covered
      by the LSM security_file_open hook if the security module implements
      checking of the requested file mode there. Otherwise, a watching process
      can obtain escalated access to a file for which it has not been authorized.
      
      The selinux_path_notify hook implementation works by adding five new file
      permissions: watch, watch_mount, watch_sb, watch_reads, and watch_with_perm
      (descriptions about which will follow), and one new filesystem permission:
      watch (which is applied to superblock checks). The hook then decides which
      subset of these permissions must be held by the requesting application
      based on the contents of the provided mask and the obj_type. The
      selinux_file_open hook already checks the requested file mode and therefore
      ensures that a watching process cannot escalate its access through
      fanotify.
      
      The watch, watch_mount, and watch_sb permissions are the baseline
      permissions for setting a watch on an object and each are a requirement for
      any watch to be set on a file, mount, or superblock respectively. It should
      be noted that having either of the other two permissions (watch_reads and
      watch_with_perm) does not imply the watch, watch_mount, or watch_sb
      permission. Superblock watches further require the filesystem watch
      permission to the superblock. As there is no labeled object in view for
      mounts, there is no specific check for mount watches beyond watch_mount to
      the inode. Such a check could be added in the future, if a suitable labeled
      object existed representing the mount.
      
      The watch_reads permission is required to receive notifications from
      read-exclusive events on filesystem objects. These events include accessing
      a file for the purpose of reading and closing a file which has been opened
      read-only. This distinction has been drawn in order to provide a direct
      indication in the policy for this otherwise not obvious capability. Read
      access to a file should not necessarily imply the ability to observe read
      events on a file.
      
      Finally, watch_with_perm only applies to fanotify masks since it is the
      only way to set a mask which allows for the blocking, permission event.
      This permission is needed for any watch which is of this type. Though
      fanotify requires CAP_SYS_ADMIN, this is insufficient as it gives implicit
      trust to root, which we do not do, and does not support least privilege.
      Signed-off-by: NAaron Goidel <acgoide@tycho.nsa.gov>
      Acked-by: NCasey Schaufler <casey@schaufler-ca.com>
      Acked-by: NJan Kara <jack@suse.cz>
      Signed-off-by: NPaul Moore <paul@paul-moore.com>
      ac5656d8
  15. 09 6月, 2019 1 次提交
  16. 27 3月, 2019 11 次提交
  17. 25 3月, 2019 1 次提交
  18. 21 3月, 2019 2 次提交
    • O
      LSM: add new hook for kernfs node initialization · b230d5ab
      Ondrej Mosnacek 提交于
      This patch introduces a new security hook that is intended for
      initializing the security data for newly created kernfs nodes, which
      provide a way of storing a non-default security context, but need to
      operate independently from mounts (and therefore may not have an
      associated inode at the moment of creation).
      
      The main motivation is to allow kernfs nodes to inherit the context of
      the parent under SELinux, similar to the behavior of
      security_inode_init_security(). Other LSMs may implement their own logic
      for handling the creation of new nodes.
      
      This patch also adds helper functions to <linux/kernfs.h> for
      getting/setting security xattrs of a kernfs node so that LSMs hooks are
      able to do their job. Other important attributes should be accessible
      direcly in the kernfs_node fields (in case there is need for more, then
      new helpers should be added to kernfs.h along with the patch that needs
      them).
      Signed-off-by: NOndrej Mosnacek <omosnace@redhat.com>
      Acked-by: NCasey Schaufler <casey@schaufler-ca.com>
      [PM: more manual merge fixes]
      Signed-off-by: NPaul Moore <paul@paul-moore.com>
      b230d5ab
    • D
      vfs: syscall: Add move_mount(2) to move mounts around · 2db154b3
      David Howells 提交于
      Add a move_mount() system call that will move a mount from one place to
      another and, in the next commit, allow to attach an unattached mount tree.
      
      The new system call looks like the following:
      
      	int move_mount(int from_dfd, const char *from_path,
      		       int to_dfd, const char *to_path,
      		       unsigned int flags);
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      cc: linux-api@vger.kernel.org
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      2db154b3
  19. 28 2月, 2019 2 次提交
    • A
      introduce cloning of fs_context · 0b52075e
      Al Viro 提交于
      new primitive: vfs_dup_fs_context().  Comes with fs_context
      method (->dup()) for copying the filesystem-specific parts
      of fs_context, along with LSM one (->fs_context_dup()) for
      doing the same to LSM parts.
      
      [needs better commit message, and change of Author:, anyway]
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      0b52075e
    • D
      vfs: Add LSM hooks for the new mount API · da2441fd
      David Howells 提交于
      Add LSM hooks for use by the new mount API and filesystem context code.
      This includes:
      
       (1) Hooks to handle allocation, duplication and freeing of the security
           record attached to a filesystem context.
      
       (2) A hook to snoop source specifications.  There may be multiple of these
           if the filesystem supports it.  They will to be local files/devices if
           fs_context::source_is_dev is true and will be something else, possibly
           remote server specifications, if false.
      
       (3) A hook to snoop superblock configuration options in key[=val] form.
           If the LSM decides it wants to handle it, it can suppress the option
           being passed to the filesystem.  Note that 'val' may include commas
           and binary data with the fsopen patch.
      
       (4) A hook to perform validation and allocation after the configuration
           has been done but before the superblock is allocated and set up.
      
       (5) A hook to transfer the security from the context to a newly created
           superblock.
      
       (6) A hook to rule on whether a path point can be used as a mountpoint.
      
      These are intended to replace:
      
      	security_sb_copy_data
      	security_sb_kern_mount
      	security_sb_mount
      	security_sb_set_mnt_opts
      	security_sb_clone_mnt_opts
      	security_sb_parse_opts_str
      
      [AV -- some of the methods being replaced are already gone, some of the
      methods are not added for the lack of need]
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      cc: linux-security-module@vger.kernel.org
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      da2441fd
  20. 01 2月, 2019 1 次提交
  21. 19 1月, 2019 1 次提交
  22. 11 1月, 2019 1 次提交
  23. 09 1月, 2019 1 次提交