2017-11-01 22:08:43 +08:00
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/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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2012-10-13 17:46:48 +08:00
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/*
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* This is <linux/capability.h>
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*
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* Andrew G. Morgan <morgan@kernel.org>
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* Alexander Kjeldaas <astor@guardian.no>
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* with help from Aleph1, Roland Buresund and Andrew Main.
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*
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* See here for the libcap library ("POSIX draft" compliance):
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*
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* ftp://www.kernel.org/pub/linux/libs/security/linux-privs/kernel-2.6/
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*/
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#ifndef _UAPI_LINUX_CAPABILITY_H
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#define _UAPI_LINUX_CAPABILITY_H
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#include <linux/types.h>
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/* User-level do most of the mapping between kernel and user
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capabilities based on the version tag given by the kernel. The
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kernel might be somewhat backwards compatible, but don't bet on
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it. */
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/* Note, cap_t, is defined by POSIX (draft) to be an "opaque" pointer to
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a set of three capability sets. The transposition of 3*the
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following structure to such a composite is better handled in a user
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library since the draft standard requires the use of malloc/free
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etc.. */
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#define _LINUX_CAPABILITY_VERSION_1 0x19980330
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#define _LINUX_CAPABILITY_U32S_1 1
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#define _LINUX_CAPABILITY_VERSION_2 0x20071026 /* deprecated - use v3 */
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#define _LINUX_CAPABILITY_U32S_2 2
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#define _LINUX_CAPABILITY_VERSION_3 0x20080522
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#define _LINUX_CAPABILITY_U32S_3 2
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typedef struct __user_cap_header_struct {
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__u32 version;
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int pid;
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} __user *cap_user_header_t;
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typedef struct __user_cap_data_struct {
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__u32 effective;
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__u32 permitted;
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__u32 inheritable;
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} __user *cap_user_data_t;
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#define VFS_CAP_REVISION_MASK 0xFF000000
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#define VFS_CAP_REVISION_SHIFT 24
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#define VFS_CAP_FLAGS_MASK ~VFS_CAP_REVISION_MASK
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#define VFS_CAP_FLAGS_EFFECTIVE 0x000001
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#define VFS_CAP_REVISION_1 0x01000000
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#define VFS_CAP_U32_1 1
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#define XATTR_CAPS_SZ_1 (sizeof(__le32)*(1 + 2*VFS_CAP_U32_1))
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#define VFS_CAP_REVISION_2 0x02000000
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#define VFS_CAP_U32_2 2
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#define XATTR_CAPS_SZ_2 (sizeof(__le32)*(1 + 2*VFS_CAP_U32_2))
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Introduce v3 namespaced file capabilities
Root in a non-initial user ns cannot be trusted to write a traditional
security.capability xattr. If it were allowed to do so, then any
unprivileged user on the host could map his own uid to root in a private
namespace, write the xattr, and execute the file with privilege on the
host.
However supporting file capabilities in a user namespace is very
desirable. Not doing so means that any programs designed to run with
limited privilege must continue to support other methods of gaining and
dropping privilege. For instance a program installer must detect
whether file capabilities can be assigned, and assign them if so but set
setuid-root otherwise. The program in turn must know how to drop
partial capabilities, and do so only if setuid-root.
This patch introduces v3 of the security.capability xattr. It builds a
vfs_ns_cap_data struct by appending a uid_t rootid to struct
vfs_cap_data. This is the absolute uid_t (that is, the uid_t in user
namespace which mounted the filesystem, usually init_user_ns) of the
root id in whose namespaces the file capabilities may take effect.
When a task asks to write a v2 security.capability xattr, if it is
privileged with respect to the userns which mounted the filesystem, then
nothing should change. Otherwise, the kernel will transparently rewrite
the xattr as a v3 with the appropriate rootid. This is done during the
execution of setxattr() to catch user-space-initiated capability writes.
Subsequently, any task executing the file which has the noted kuid as
its root uid, or which is in a descendent user_ns of such a user_ns,
will run the file with capabilities.
Similarly when asking to read file capabilities, a v3 capability will
be presented as v2 if it applies to the caller's namespace.
If a task writes a v3 security.capability, then it can provide a uid for
the xattr so long as the uid is valid in its own user namespace, and it
is privileged with CAP_SETFCAP over its namespace. The kernel will
translate that rootid to an absolute uid, and write that to disk. After
this, a task in the writer's namespace will not be able to use those
capabilities (unless rootid was 0), but a task in a namespace where the
given uid is root will.
Only a single security.capability xattr may exist at a time for a given
file. A task may overwrite an existing xattr so long as it is
privileged over the inode. Note this is a departure from previous
semantics, which required privilege to remove a security.capability
xattr. This check can be re-added if deemed useful.
This allows a simple setxattr to work, allows tar/untar to work, and
allows us to tar in one namespace and untar in another while preserving
the capability, without risking leaking privilege into a parent
namespace.
Example using tar:
$ cp /bin/sleep sleepx
$ mkdir b1 b2
$ lxc-usernsexec -m b:0:100000:1 -m b:1:$(id -u):1 -- chown 0:0 b1
$ lxc-usernsexec -m b:0:100001:1 -m b:1:$(id -u):1 -- chown 0:0 b2
$ lxc-usernsexec -m b:0:100000:1000 -- tar --xattrs-include=security.capability --xattrs -cf b1/sleepx.tar sleepx
$ lxc-usernsexec -m b:0:100001:1000 -- tar --xattrs-include=security.capability --xattrs -C b2 -xf b1/sleepx.tar
$ lxc-usernsexec -m b:0:100001:1000 -- getcap b2/sleepx
b2/sleepx = cap_sys_admin+ep
# /opt/ltp/testcases/bin/getv3xattr b2/sleepx
v3 xattr, rootid is 100001
A patch to linux-test-project adding a new set of tests for this
functionality is in the nsfscaps branch at github.com/hallyn/ltp
Changelog:
Nov 02 2016: fix invalid check at refuse_fcap_overwrite()
Nov 07 2016: convert rootid from and to fs user_ns
(From ebiederm: mar 28 2017)
commoncap.c: fix typos - s/v4/v3
get_vfs_caps_from_disk: clarify the fs_ns root access check
nsfscaps: change the code split for cap_inode_setxattr()
Apr 09 2017:
don't return v3 cap for caps owned by current root.
return a v2 cap for a true v2 cap in non-init ns
Apr 18 2017:
. Change the flow of fscap writing to support s_user_ns writing.
. Remove refuse_fcap_overwrite(). The value of the previous
xattr doesn't matter.
Apr 24 2017:
. incorporate Eric's incremental diff
. move cap_convert_nscap to setxattr and simplify its usage
May 8, 2017:
. fix leaking dentry refcount in cap_inode_getsecurity
Signed-off-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2017-05-09 02:11:56 +08:00
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#define VFS_CAP_REVISION_3 0x03000000
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#define VFS_CAP_U32_3 2
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#define XATTR_CAPS_SZ_3 (sizeof(__le32)*(2 + 2*VFS_CAP_U32_3))
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#define XATTR_CAPS_SZ XATTR_CAPS_SZ_3
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#define VFS_CAP_U32 VFS_CAP_U32_3
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#define VFS_CAP_REVISION VFS_CAP_REVISION_3
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2012-10-13 17:46:48 +08:00
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struct vfs_cap_data {
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__le32 magic_etc; /* Little endian */
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struct {
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__le32 permitted; /* Little endian */
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__le32 inheritable; /* Little endian */
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} data[VFS_CAP_U32];
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};
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Introduce v3 namespaced file capabilities
Root in a non-initial user ns cannot be trusted to write a traditional
security.capability xattr. If it were allowed to do so, then any
unprivileged user on the host could map his own uid to root in a private
namespace, write the xattr, and execute the file with privilege on the
host.
However supporting file capabilities in a user namespace is very
desirable. Not doing so means that any programs designed to run with
limited privilege must continue to support other methods of gaining and
dropping privilege. For instance a program installer must detect
whether file capabilities can be assigned, and assign them if so but set
setuid-root otherwise. The program in turn must know how to drop
partial capabilities, and do so only if setuid-root.
This patch introduces v3 of the security.capability xattr. It builds a
vfs_ns_cap_data struct by appending a uid_t rootid to struct
vfs_cap_data. This is the absolute uid_t (that is, the uid_t in user
namespace which mounted the filesystem, usually init_user_ns) of the
root id in whose namespaces the file capabilities may take effect.
When a task asks to write a v2 security.capability xattr, if it is
privileged with respect to the userns which mounted the filesystem, then
nothing should change. Otherwise, the kernel will transparently rewrite
the xattr as a v3 with the appropriate rootid. This is done during the
execution of setxattr() to catch user-space-initiated capability writes.
Subsequently, any task executing the file which has the noted kuid as
its root uid, or which is in a descendent user_ns of such a user_ns,
will run the file with capabilities.
Similarly when asking to read file capabilities, a v3 capability will
be presented as v2 if it applies to the caller's namespace.
If a task writes a v3 security.capability, then it can provide a uid for
the xattr so long as the uid is valid in its own user namespace, and it
is privileged with CAP_SETFCAP over its namespace. The kernel will
translate that rootid to an absolute uid, and write that to disk. After
this, a task in the writer's namespace will not be able to use those
capabilities (unless rootid was 0), but a task in a namespace where the
given uid is root will.
Only a single security.capability xattr may exist at a time for a given
file. A task may overwrite an existing xattr so long as it is
privileged over the inode. Note this is a departure from previous
semantics, which required privilege to remove a security.capability
xattr. This check can be re-added if deemed useful.
This allows a simple setxattr to work, allows tar/untar to work, and
allows us to tar in one namespace and untar in another while preserving
the capability, without risking leaking privilege into a parent
namespace.
Example using tar:
$ cp /bin/sleep sleepx
$ mkdir b1 b2
$ lxc-usernsexec -m b:0:100000:1 -m b:1:$(id -u):1 -- chown 0:0 b1
$ lxc-usernsexec -m b:0:100001:1 -m b:1:$(id -u):1 -- chown 0:0 b2
$ lxc-usernsexec -m b:0:100000:1000 -- tar --xattrs-include=security.capability --xattrs -cf b1/sleepx.tar sleepx
$ lxc-usernsexec -m b:0:100001:1000 -- tar --xattrs-include=security.capability --xattrs -C b2 -xf b1/sleepx.tar
$ lxc-usernsexec -m b:0:100001:1000 -- getcap b2/sleepx
b2/sleepx = cap_sys_admin+ep
# /opt/ltp/testcases/bin/getv3xattr b2/sleepx
v3 xattr, rootid is 100001
A patch to linux-test-project adding a new set of tests for this
functionality is in the nsfscaps branch at github.com/hallyn/ltp
Changelog:
Nov 02 2016: fix invalid check at refuse_fcap_overwrite()
Nov 07 2016: convert rootid from and to fs user_ns
(From ebiederm: mar 28 2017)
commoncap.c: fix typos - s/v4/v3
get_vfs_caps_from_disk: clarify the fs_ns root access check
nsfscaps: change the code split for cap_inode_setxattr()
Apr 09 2017:
don't return v3 cap for caps owned by current root.
return a v2 cap for a true v2 cap in non-init ns
Apr 18 2017:
. Change the flow of fscap writing to support s_user_ns writing.
. Remove refuse_fcap_overwrite(). The value of the previous
xattr doesn't matter.
Apr 24 2017:
. incorporate Eric's incremental diff
. move cap_convert_nscap to setxattr and simplify its usage
May 8, 2017:
. fix leaking dentry refcount in cap_inode_getsecurity
Signed-off-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2017-05-09 02:11:56 +08:00
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/*
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* same as vfs_cap_data but with a rootid at the end
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*/
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struct vfs_ns_cap_data {
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__le32 magic_etc;
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struct {
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__le32 permitted; /* Little endian */
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__le32 inheritable; /* Little endian */
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} data[VFS_CAP_U32];
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__le32 rootid;
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};
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2012-10-13 17:46:48 +08:00
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#ifndef __KERNEL__
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/*
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* Backwardly compatible definition for source code - trapped in a
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* 32-bit world. If you find you need this, please consider using
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* libcap to untrap yourself...
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*/
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#define _LINUX_CAPABILITY_VERSION _LINUX_CAPABILITY_VERSION_1
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#define _LINUX_CAPABILITY_U32S _LINUX_CAPABILITY_U32S_1
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#endif
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/**
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** POSIX-draft defined capabilities.
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**/
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/* In a system with the [_POSIX_CHOWN_RESTRICTED] option defined, this
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overrides the restriction of changing file ownership and group
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ownership. */
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#define CAP_CHOWN 0
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/* Override all DAC access, including ACL execute access if
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[_POSIX_ACL] is defined. Excluding DAC access covered by
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CAP_LINUX_IMMUTABLE. */
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#define CAP_DAC_OVERRIDE 1
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/* Overrides all DAC restrictions regarding read and search on files
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and directories, including ACL restrictions if [_POSIX_ACL] is
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defined. Excluding DAC access covered by CAP_LINUX_IMMUTABLE. */
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#define CAP_DAC_READ_SEARCH 2
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/* Overrides all restrictions about allowed operations on files, where
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file owner ID must be equal to the user ID, except where CAP_FSETID
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is applicable. It doesn't override MAC and DAC restrictions. */
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#define CAP_FOWNER 3
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/* Overrides the following restrictions that the effective user ID
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shall match the file owner ID when setting the S_ISUID and S_ISGID
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bits on that file; that the effective group ID (or one of the
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supplementary group IDs) shall match the file owner ID when setting
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the S_ISGID bit on that file; that the S_ISUID and S_ISGID bits are
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cleared on successful return from chown(2) (not implemented). */
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#define CAP_FSETID 4
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/* Overrides the restriction that the real or effective user ID of a
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process sending a signal must match the real or effective user ID
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of the process receiving the signal. */
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#define CAP_KILL 5
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/* Allows setgid(2) manipulation */
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/* Allows setgroups(2) */
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/* Allows forged gids on socket credentials passing. */
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#define CAP_SETGID 6
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/* Allows set*uid(2) manipulation (including fsuid). */
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/* Allows forged pids on socket credentials passing. */
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#define CAP_SETUID 7
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/**
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** Linux-specific capabilities
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**/
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/* Without VFS support for capabilities:
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* Transfer any capability in your permitted set to any pid,
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* remove any capability in your permitted set from any pid
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* With VFS support for capabilities (neither of above, but)
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* Add any capability from current's capability bounding set
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* to the current process' inheritable set
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* Allow taking bits out of capability bounding set
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* Allow modification of the securebits for a process
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*/
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#define CAP_SETPCAP 8
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/* Allow modification of S_IMMUTABLE and S_APPEND file attributes */
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#define CAP_LINUX_IMMUTABLE 9
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/* Allows binding to TCP/UDP sockets below 1024 */
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/* Allows binding to ATM VCIs below 32 */
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#define CAP_NET_BIND_SERVICE 10
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/* Allow broadcasting, listen to multicast */
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#define CAP_NET_BROADCAST 11
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/* Allow interface configuration */
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/* Allow administration of IP firewall, masquerading and accounting */
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/* Allow setting debug option on sockets */
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/* Allow modification of routing tables */
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/* Allow setting arbitrary process / process group ownership on
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sockets */
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/* Allow binding to any address for transparent proxying (also via NET_RAW) */
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/* Allow setting TOS (type of service) */
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/* Allow setting promiscuous mode */
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/* Allow clearing driver statistics */
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/* Allow multicasting */
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/* Allow read/write of device-specific registers */
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/* Allow activation of ATM control sockets */
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#define CAP_NET_ADMIN 12
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/* Allow use of RAW sockets */
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/* Allow use of PACKET sockets */
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/* Allow binding to any address for transparent proxying (also via NET_ADMIN) */
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#define CAP_NET_RAW 13
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/* Allow locking of shared memory segments */
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/* Allow mlock and mlockall (which doesn't really have anything to do
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with IPC) */
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#define CAP_IPC_LOCK 14
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/* Override IPC ownership checks */
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#define CAP_IPC_OWNER 15
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/* Insert and remove kernel modules - modify kernel without limit */
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#define CAP_SYS_MODULE 16
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/* Allow ioperm/iopl access */
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2017-04-17 08:51:07 +08:00
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/* Allow sending USB messages to any device via /dev/bus/usb */
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2012-10-13 17:46:48 +08:00
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#define CAP_SYS_RAWIO 17
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/* Allow use of chroot() */
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#define CAP_SYS_CHROOT 18
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/* Allow ptrace() of any process */
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#define CAP_SYS_PTRACE 19
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/* Allow configuration of process accounting */
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#define CAP_SYS_PACCT 20
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/* Allow configuration of the secure attention key */
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/* Allow administration of the random device */
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/* Allow examination and configuration of disk quotas */
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/* Allow setting the domainname */
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/* Allow setting the hostname */
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/* Allow calling bdflush() */
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/* Allow mount() and umount(), setting up new smb connection */
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/* Allow some autofs root ioctls */
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/* Allow nfsservctl */
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/* Allow VM86_REQUEST_IRQ */
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/* Allow to read/write pci config on alpha */
|
|
|
|
/* Allow irix_prctl on mips (setstacksize) */
|
|
|
|
/* Allow flushing all cache on m68k (sys_cacheflush) */
|
|
|
|
/* Allow removing semaphores */
|
|
|
|
/* Used instead of CAP_CHOWN to "chown" IPC message queues, semaphores
|
|
|
|
and shared memory */
|
|
|
|
/* Allow locking/unlocking of shared memory segment */
|
|
|
|
/* Allow turning swap on/off */
|
|
|
|
/* Allow forged pids on socket credentials passing */
|
|
|
|
/* Allow setting readahead and flushing buffers on block devices */
|
|
|
|
/* Allow setting geometry in floppy driver */
|
|
|
|
/* Allow turning DMA on/off in xd driver */
|
|
|
|
/* Allow administration of md devices (mostly the above, but some
|
|
|
|
extra ioctls) */
|
|
|
|
/* Allow tuning the ide driver */
|
|
|
|
/* Allow access to the nvram device */
|
|
|
|
/* Allow administration of apm_bios, serial and bttv (TV) device */
|
|
|
|
/* Allow manufacturer commands in isdn CAPI support driver */
|
|
|
|
/* Allow reading non-standardized portions of pci configuration space */
|
|
|
|
/* Allow DDI debug ioctl on sbpcd driver */
|
|
|
|
/* Allow setting up serial ports */
|
|
|
|
/* Allow sending raw qic-117 commands */
|
|
|
|
/* Allow enabling/disabling tagged queuing on SCSI controllers and sending
|
|
|
|
arbitrary SCSI commands */
|
|
|
|
/* Allow setting encryption key on loopback filesystem */
|
|
|
|
/* Allow setting zone reclaim policy */
|
bpf, capability: Introduce CAP_BPF
Split BPF operations that are allowed under CAP_SYS_ADMIN into
combination of CAP_BPF, CAP_PERFMON, CAP_NET_ADMIN.
For backward compatibility include them in CAP_SYS_ADMIN as well.
The end result provides simple safety model for applications that use BPF:
- to load tracing program types
BPF_PROG_TYPE_{KPROBE, TRACEPOINT, PERF_EVENT, RAW_TRACEPOINT, etc}
use CAP_BPF and CAP_PERFMON
- to load networking program types
BPF_PROG_TYPE_{SCHED_CLS, XDP, SK_SKB, etc}
use CAP_BPF and CAP_NET_ADMIN
There are few exceptions from this rule:
- bpf_trace_printk() is allowed in networking programs, but it's using
tracing mechanism, hence this helper needs additional CAP_PERFMON
if networking program is using this helper.
- BPF_F_ZERO_SEED flag for hash/lru map is allowed under CAP_SYS_ADMIN only
to discourage production use.
- BPF HW offload is allowed under CAP_SYS_ADMIN.
- bpf_probe_write_user() is allowed under CAP_SYS_ADMIN only.
CAPs are not checked at attach/detach time with two exceptions:
- loading BPF_PROG_TYPE_CGROUP_SKB is allowed for unprivileged users,
hence CAP_NET_ADMIN is required at attach time.
- flow_dissector detach doesn't check prog FD at detach,
hence CAP_NET_ADMIN is required at detach time.
CAP_SYS_ADMIN is required to iterate BPF objects (progs, maps, links) via get_next_id
command and convert them to file descriptor via GET_FD_BY_ID command.
This restriction guarantees that mutliple tasks with CAP_BPF are not able to
affect each other. That leads to clean isolation of tasks. For example:
task A with CAP_BPF and CAP_NET_ADMIN loads and attaches a firewall via bpf_link.
task B with the same capabilities cannot detach that firewall unless
task A explicitly passed link FD to task B via scm_rights or bpffs.
CAP_SYS_ADMIN can still detach/unload everything.
Two networking user apps with CAP_SYS_ADMIN and CAP_NET_ADMIN can
accidentely mess with each other programs and maps.
Two networking user apps with CAP_NET_ADMIN and CAP_BPF cannot affect each other.
CAP_NET_ADMIN + CAP_BPF allows networking programs access only packet data.
Such networking progs cannot access arbitrary kernel memory or leak pointers.
bpftool, bpftrace, bcc tools binaries should NOT be installed with
CAP_BPF and CAP_PERFMON, since unpriv users will be able to read kernel secrets.
But users with these two permissions will be able to use these tracing tools.
CAP_PERFMON is least secure, since it allows kprobes and kernel memory access.
CAP_NET_ADMIN can stop network traffic via iproute2.
CAP_BPF is the safest from security point of view and harmless on its own.
Having CAP_BPF and/or CAP_NET_ADMIN is not enough to write into arbitrary map
and if that map is used by firewall-like bpf prog.
CAP_BPF allows many bpf prog_load commands in parallel. The verifier
may consume large amount of memory and significantly slow down the system.
Existing unprivileged BPF operations are not affected.
In particular unprivileged users are allowed to load socket_filter and cg_skb
program types and to create array, hash, prog_array, map-in-map map types.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200513230355.7858-2-alexei.starovoitov@gmail.com
2020-05-14 07:03:53 +08:00
|
|
|
/* Allow everything under CAP_BPF and CAP_PERFMON for backward compatibility */
|
2012-10-13 17:46:48 +08:00
|
|
|
|
|
|
|
#define CAP_SYS_ADMIN 21
|
|
|
|
|
|
|
|
/* Allow use of reboot() */
|
|
|
|
|
|
|
|
#define CAP_SYS_BOOT 22
|
|
|
|
|
|
|
|
/* Allow raising priority and setting priority on other (different
|
|
|
|
UID) processes */
|
|
|
|
/* Allow use of FIFO and round-robin (realtime) scheduling on own
|
|
|
|
processes and setting the scheduling algorithm used by another
|
|
|
|
process. */
|
|
|
|
/* Allow setting cpu affinity on other processes */
|
2020-08-25 06:10:34 +08:00
|
|
|
/* Allow setting realtime ioprio class */
|
|
|
|
/* Allow setting ioprio class on other processes */
|
2012-10-13 17:46:48 +08:00
|
|
|
|
|
|
|
#define CAP_SYS_NICE 23
|
|
|
|
|
|
|
|
/* Override resource limits. Set resource limits. */
|
|
|
|
/* Override quota limits. */
|
|
|
|
/* Override reserved space on ext2 filesystem */
|
|
|
|
/* Modify data journaling mode on ext3 filesystem (uses journaling
|
|
|
|
resources) */
|
|
|
|
/* NOTE: ext2 honors fsuid when checking for resource overrides, so
|
|
|
|
you can override using fsuid too */
|
|
|
|
/* Override size restrictions on IPC message queues */
|
|
|
|
/* Allow more than 64hz interrupts from the real-time clock */
|
|
|
|
/* Override max number of consoles on console allocation */
|
|
|
|
/* Override max number of keymaps */
|
prctl: PR_{G,S}ET_IO_FLUSHER to support controlling memory reclaim
There are several storage drivers like dm-multipath, iscsi, tcmu-runner,
amd nbd that have userspace components that can run in the IO path. For
example, iscsi and nbd's userspace deamons may need to recreate a socket
and/or send IO on it, and dm-multipath's daemon multipathd may need to
send SG IO or read/write IO to figure out the state of paths and re-set
them up.
In the kernel these drivers have access to GFP_NOIO/GFP_NOFS and the
memalloc_*_save/restore functions to control the allocation behavior,
but for userspace we would end up hitting an allocation that ended up
writing data back to the same device we are trying to allocate for.
The device is then in a state of deadlock, because to execute IO the
device needs to allocate memory, but to allocate memory the memory
layers want execute IO to the device.
Here is an example with nbd using a local userspace daemon that performs
network IO to a remote server. We are using XFS on top of the nbd device,
but it can happen with any FS or other modules layered on top of the nbd
device that can write out data to free memory. Here a nbd daemon helper
thread, msgr-worker-1, is performing a write/sendmsg on a socket to execute
a request. This kicks off a reclaim operation which results in a WRITE to
the nbd device and the nbd thread calling back into the mm layer.
[ 1626.609191] msgr-worker-1 D 0 1026 1 0x00004000
[ 1626.609193] Call Trace:
[ 1626.609195] ? __schedule+0x29b/0x630
[ 1626.609197] ? wait_for_completion+0xe0/0x170
[ 1626.609198] schedule+0x30/0xb0
[ 1626.609200] schedule_timeout+0x1f6/0x2f0
[ 1626.609202] ? blk_finish_plug+0x21/0x2e
[ 1626.609204] ? _xfs_buf_ioapply+0x2e6/0x410
[ 1626.609206] ? wait_for_completion+0xe0/0x170
[ 1626.609208] wait_for_completion+0x108/0x170
[ 1626.609210] ? wake_up_q+0x70/0x70
[ 1626.609212] ? __xfs_buf_submit+0x12e/0x250
[ 1626.609214] ? xfs_bwrite+0x25/0x60
[ 1626.609215] xfs_buf_iowait+0x22/0xf0
[ 1626.609218] __xfs_buf_submit+0x12e/0x250
[ 1626.609220] xfs_bwrite+0x25/0x60
[ 1626.609222] xfs_reclaim_inode+0x2e8/0x310
[ 1626.609224] xfs_reclaim_inodes_ag+0x1b6/0x300
[ 1626.609227] xfs_reclaim_inodes_nr+0x31/0x40
[ 1626.609228] super_cache_scan+0x152/0x1a0
[ 1626.609231] do_shrink_slab+0x12c/0x2d0
[ 1626.609233] shrink_slab+0x9c/0x2a0
[ 1626.609235] shrink_node+0xd7/0x470
[ 1626.609237] do_try_to_free_pages+0xbf/0x380
[ 1626.609240] try_to_free_pages+0xd9/0x1f0
[ 1626.609245] __alloc_pages_slowpath+0x3a4/0xd30
[ 1626.609251] ? ___slab_alloc+0x238/0x560
[ 1626.609254] __alloc_pages_nodemask+0x30c/0x350
[ 1626.609259] skb_page_frag_refill+0x97/0xd0
[ 1626.609274] sk_page_frag_refill+0x1d/0x80
[ 1626.609279] tcp_sendmsg_locked+0x2bb/0xdd0
[ 1626.609304] tcp_sendmsg+0x27/0x40
[ 1626.609307] sock_sendmsg+0x54/0x60
[ 1626.609308] ___sys_sendmsg+0x29f/0x320
[ 1626.609313] ? sock_poll+0x66/0xb0
[ 1626.609318] ? ep_item_poll.isra.15+0x40/0xc0
[ 1626.609320] ? ep_send_events_proc+0xe6/0x230
[ 1626.609322] ? hrtimer_try_to_cancel+0x54/0xf0
[ 1626.609324] ? ep_read_events_proc+0xc0/0xc0
[ 1626.609326] ? _raw_write_unlock_irq+0xa/0x20
[ 1626.609327] ? ep_scan_ready_list.constprop.19+0x218/0x230
[ 1626.609329] ? __hrtimer_init+0xb0/0xb0
[ 1626.609331] ? _raw_spin_unlock_irq+0xa/0x20
[ 1626.609334] ? ep_poll+0x26c/0x4a0
[ 1626.609337] ? tcp_tsq_write.part.54+0xa0/0xa0
[ 1626.609339] ? release_sock+0x43/0x90
[ 1626.609341] ? _raw_spin_unlock_bh+0xa/0x20
[ 1626.609342] __sys_sendmsg+0x47/0x80
[ 1626.609347] do_syscall_64+0x5f/0x1c0
[ 1626.609349] ? prepare_exit_to_usermode+0x75/0xa0
[ 1626.609351] entry_SYSCALL_64_after_hwframe+0x44/0xa9
This patch adds a new prctl command that daemons can use after they have
done their initial setup, and before they start to do allocations that
are in the IO path. It sets the PF_MEMALLOC_NOIO and PF_LESS_THROTTLE
flags so both userspace block and FS threads can use it to avoid the
allocation recursion and try to prevent from being throttled while
writing out data to free up memory.
Signed-off-by: Mike Christie <mchristi@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Tested-by: Masato Suzuki <masato.suzuki@wdc.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Link: https://lore.kernel.org/r/20191112001900.9206-1-mchristi@redhat.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2019-11-12 08:19:00 +08:00
|
|
|
/* Control memory reclaim behavior */
|
2012-10-13 17:46:48 +08:00
|
|
|
|
|
|
|
#define CAP_SYS_RESOURCE 24
|
|
|
|
|
|
|
|
/* Allow manipulation of system clock */
|
|
|
|
/* Allow irix_stime on mips */
|
|
|
|
/* Allow setting the real-time clock */
|
|
|
|
|
|
|
|
#define CAP_SYS_TIME 25
|
|
|
|
|
|
|
|
/* Allow configuration of tty devices */
|
|
|
|
/* Allow vhangup() of tty */
|
|
|
|
|
|
|
|
#define CAP_SYS_TTY_CONFIG 26
|
|
|
|
|
|
|
|
/* Allow the privileged aspects of mknod() */
|
|
|
|
|
|
|
|
#define CAP_MKNOD 27
|
|
|
|
|
|
|
|
/* Allow taking of leases on files */
|
|
|
|
|
|
|
|
#define CAP_LEASE 28
|
|
|
|
|
2014-01-28 07:16:55 +08:00
|
|
|
/* Allow writing the audit log via unicast netlink socket */
|
|
|
|
|
2012-10-13 17:46:48 +08:00
|
|
|
#define CAP_AUDIT_WRITE 29
|
|
|
|
|
2014-01-28 07:16:55 +08:00
|
|
|
/* Allow configuration of audit via unicast netlink socket */
|
|
|
|
|
2012-10-13 17:46:48 +08:00
|
|
|
#define CAP_AUDIT_CONTROL 30
|
|
|
|
|
2020-06-02 17:17:28 +08:00
|
|
|
/* Set or remove capabilities on files */
|
|
|
|
|
2012-10-13 17:46:48 +08:00
|
|
|
#define CAP_SETFCAP 31
|
|
|
|
|
|
|
|
/* Override MAC access.
|
|
|
|
The base kernel enforces no MAC policy.
|
|
|
|
An LSM may enforce a MAC policy, and if it does and it chooses
|
|
|
|
to implement capability based overrides of that policy, this is
|
|
|
|
the capability it should use to do so. */
|
|
|
|
|
|
|
|
#define CAP_MAC_OVERRIDE 32
|
|
|
|
|
|
|
|
/* Allow MAC configuration or state changes.
|
|
|
|
The base kernel requires no MAC configuration.
|
|
|
|
An LSM may enforce a MAC policy, and if it does and it chooses
|
|
|
|
to implement capability based checks on modifications to that
|
|
|
|
policy or the data required to maintain it, this is the
|
|
|
|
capability it should use to do so. */
|
|
|
|
|
|
|
|
#define CAP_MAC_ADMIN 33
|
|
|
|
|
|
|
|
/* Allow configuring the kernel's syslog (printk behaviour) */
|
|
|
|
|
|
|
|
#define CAP_SYSLOG 34
|
|
|
|
|
|
|
|
/* Allow triggering something that will wake the system */
|
|
|
|
|
|
|
|
#define CAP_WAKE_ALARM 35
|
|
|
|
|
|
|
|
/* Allow preventing system suspends */
|
|
|
|
|
|
|
|
#define CAP_BLOCK_SUSPEND 36
|
|
|
|
|
2014-04-23 09:31:56 +08:00
|
|
|
/* Allow reading the audit log via multicast netlink socket */
|
|
|
|
|
|
|
|
#define CAP_AUDIT_READ 37
|
|
|
|
|
capabilities: Introduce CAP_PERFMON to kernel and user space
Introduce the CAP_PERFMON capability designed to secure system
performance monitoring and observability operations so that CAP_PERFMON
can assist CAP_SYS_ADMIN capability in its governing role for
performance monitoring and observability subsystems.
CAP_PERFMON hardens system security and integrity during performance
monitoring and observability operations by decreasing attack surface that
is available to a CAP_SYS_ADMIN privileged process [2]. Providing the access
to system performance monitoring and observability operations under CAP_PERFMON
capability singly, without the rest of CAP_SYS_ADMIN credentials, excludes
chances to misuse the credentials and makes the operation more secure.
Thus, CAP_PERFMON implements the principle of least privilege for
performance monitoring and observability operations (POSIX IEEE 1003.1e:
2.2.2.39 principle of least privilege: A security design principle that
states that a process or program be granted only those privileges
(e.g., capabilities) necessary to accomplish its legitimate function,
and only for the time that such privileges are actually required)
CAP_PERFMON meets the demand to secure system performance monitoring and
observability operations for adoption in security sensitive, restricted,
multiuser production environments (e.g. HPC clusters, cloud and virtual compute
environments), where root or CAP_SYS_ADMIN credentials are not available to
mass users of a system, and securely unblocks applicability and scalability
of system performance monitoring and observability operations beyond root
and CAP_SYS_ADMIN use cases.
CAP_PERFMON takes over CAP_SYS_ADMIN credentials related to system performance
monitoring and observability operations and balances amount of CAP_SYS_ADMIN
credentials following the recommendations in the capabilities man page [1]
for CAP_SYS_ADMIN: "Note: this capability is overloaded; see Notes to kernel
developers, below." For backward compatibility reasons access to system
performance monitoring and observability subsystems of the kernel remains
open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN capability
usage for secure system performance monitoring and observability operations
is discouraged with respect to the designed CAP_PERFMON capability.
Although the software running under CAP_PERFMON can not ensure avoidance
of related hardware issues, the software can still mitigate these issues
following the official hardware issues mitigation procedure [2]. The bugs
in the software itself can be fixed following the standard kernel development
process [3] to maintain and harden security of system performance monitoring
and observability operations.
[1] http://man7.org/linux/man-pages/man7/capabilities.7.html
[2] https://www.kernel.org/doc/html/latest/process/embargoed-hardware-issues.html
[3] https://www.kernel.org/doc/html/latest/admin-guide/security-bugs.html
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Serge E. Hallyn <serge@hallyn.com>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/5590d543-82c6-490a-6544-08e6a5517db0@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2020-04-02 16:45:31 +08:00
|
|
|
/*
|
|
|
|
* Allow system performance and observability privileged operations
|
|
|
|
* using perf_events, i915_perf and other kernel subsystems
|
|
|
|
*/
|
|
|
|
|
|
|
|
#define CAP_PERFMON 38
|
2014-04-23 09:31:56 +08:00
|
|
|
|
bpf, capability: Introduce CAP_BPF
Split BPF operations that are allowed under CAP_SYS_ADMIN into
combination of CAP_BPF, CAP_PERFMON, CAP_NET_ADMIN.
For backward compatibility include them in CAP_SYS_ADMIN as well.
The end result provides simple safety model for applications that use BPF:
- to load tracing program types
BPF_PROG_TYPE_{KPROBE, TRACEPOINT, PERF_EVENT, RAW_TRACEPOINT, etc}
use CAP_BPF and CAP_PERFMON
- to load networking program types
BPF_PROG_TYPE_{SCHED_CLS, XDP, SK_SKB, etc}
use CAP_BPF and CAP_NET_ADMIN
There are few exceptions from this rule:
- bpf_trace_printk() is allowed in networking programs, but it's using
tracing mechanism, hence this helper needs additional CAP_PERFMON
if networking program is using this helper.
- BPF_F_ZERO_SEED flag for hash/lru map is allowed under CAP_SYS_ADMIN only
to discourage production use.
- BPF HW offload is allowed under CAP_SYS_ADMIN.
- bpf_probe_write_user() is allowed under CAP_SYS_ADMIN only.
CAPs are not checked at attach/detach time with two exceptions:
- loading BPF_PROG_TYPE_CGROUP_SKB is allowed for unprivileged users,
hence CAP_NET_ADMIN is required at attach time.
- flow_dissector detach doesn't check prog FD at detach,
hence CAP_NET_ADMIN is required at detach time.
CAP_SYS_ADMIN is required to iterate BPF objects (progs, maps, links) via get_next_id
command and convert them to file descriptor via GET_FD_BY_ID command.
This restriction guarantees that mutliple tasks with CAP_BPF are not able to
affect each other. That leads to clean isolation of tasks. For example:
task A with CAP_BPF and CAP_NET_ADMIN loads and attaches a firewall via bpf_link.
task B with the same capabilities cannot detach that firewall unless
task A explicitly passed link FD to task B via scm_rights or bpffs.
CAP_SYS_ADMIN can still detach/unload everything.
Two networking user apps with CAP_SYS_ADMIN and CAP_NET_ADMIN can
accidentely mess with each other programs and maps.
Two networking user apps with CAP_NET_ADMIN and CAP_BPF cannot affect each other.
CAP_NET_ADMIN + CAP_BPF allows networking programs access only packet data.
Such networking progs cannot access arbitrary kernel memory or leak pointers.
bpftool, bpftrace, bcc tools binaries should NOT be installed with
CAP_BPF and CAP_PERFMON, since unpriv users will be able to read kernel secrets.
But users with these two permissions will be able to use these tracing tools.
CAP_PERFMON is least secure, since it allows kprobes and kernel memory access.
CAP_NET_ADMIN can stop network traffic via iproute2.
CAP_BPF is the safest from security point of view and harmless on its own.
Having CAP_BPF and/or CAP_NET_ADMIN is not enough to write into arbitrary map
and if that map is used by firewall-like bpf prog.
CAP_BPF allows many bpf prog_load commands in parallel. The verifier
may consume large amount of memory and significantly slow down the system.
Existing unprivileged BPF operations are not affected.
In particular unprivileged users are allowed to load socket_filter and cg_skb
program types and to create array, hash, prog_array, map-in-map map types.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200513230355.7858-2-alexei.starovoitov@gmail.com
2020-05-14 07:03:53 +08:00
|
|
|
/*
|
|
|
|
* CAP_BPF allows the following BPF operations:
|
|
|
|
* - Creating all types of BPF maps
|
|
|
|
* - Advanced verifier features
|
|
|
|
* - Indirect variable access
|
|
|
|
* - Bounded loops
|
|
|
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* - BPF to BPF function calls
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* - Scalar precision tracking
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* - Larger complexity limits
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* - Dead code elimination
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* - And potentially other features
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* - Loading BPF Type Format (BTF) data
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* - Retrieve xlated and JITed code of BPF programs
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* - Use bpf_spin_lock() helper
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*
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* CAP_PERFMON relaxes the verifier checks further:
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* - BPF progs can use of pointer-to-integer conversions
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* - speculation attack hardening measures are bypassed
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* - bpf_probe_read to read arbitrary kernel memory is allowed
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* - bpf_trace_printk to print kernel memory is allowed
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*
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* CAP_SYS_ADMIN is required to use bpf_probe_write_user.
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*
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* CAP_SYS_ADMIN is required to iterate system wide loaded
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* programs, maps, links, BTFs and convert their IDs to file descriptors.
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*
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* CAP_PERFMON and CAP_BPF are required to load tracing programs.
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* CAP_NET_ADMIN and CAP_BPF are required to load networking programs.
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*/
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#define CAP_BPF 39
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capabilities: Introduce CAP_CHECKPOINT_RESTORE
This patch introduces CAP_CHECKPOINT_RESTORE, a new capability facilitating
checkpoint/restore for non-root users.
Over the last years, The CRIU (Checkpoint/Restore In Userspace) team has
been asked numerous times if it is possible to checkpoint/restore a
process as non-root. The answer usually was: 'almost'.
The main blocker to restore a process as non-root was to control the PID
of the restored process. This feature available via the clone3 system
call, or via /proc/sys/kernel/ns_last_pid is unfortunately guarded by
CAP_SYS_ADMIN.
In the past two years, requests for non-root checkpoint/restore have
increased due to the following use cases:
* Checkpoint/Restore in an HPC environment in combination with a
resource manager distributing jobs where users are always running as
non-root. There is a desire to provide a way to checkpoint and
restore long running jobs.
* Container migration as non-root
* We have been in contact with JVM developers who are integrating
CRIU into a Java VM to decrease the startup time. These
checkpoint/restore applications are not meant to be running with
CAP_SYS_ADMIN.
We have seen the following workarounds:
* Use a setuid wrapper around CRIU:
See https://github.com/FredHutch/slurm-examples/blob/master/checkpointer/lib/checkpointer/checkpointer-suid.c
* Use a setuid helper that writes to ns_last_pid.
Unfortunately, this helper delegation technique is impossible to use
with clone3, and is thus prone to races.
See https://github.com/twosigma/set_ns_last_pid
* Cycle through PIDs with fork() until the desired PID is reached:
This has been demonstrated to work with cycling rates of 100,000 PIDs/s
See https://github.com/twosigma/set_ns_last_pid
* Patch out the CAP_SYS_ADMIN check from the kernel
* Run the desired application in a new user and PID namespace to provide
a local CAP_SYS_ADMIN for controlling PIDs. This technique has limited
use in typical container environments (e.g., Kubernetes) as /proc is
typically protected with read-only layers (e.g., /proc/sys) for
hardening purposes. Read-only layers prevent additional /proc mounts
(due to proc's SB_I_USERNS_VISIBLE property), making the use of new
PID namespaces limited as certain applications need access to /proc
matching their PID namespace.
The introduced capability allows to:
* Control PIDs when the current user is CAP_CHECKPOINT_RESTORE capable
for the corresponding PID namespace via ns_last_pid/clone3.
* Open files in /proc/pid/map_files when the current user is
CAP_CHECKPOINT_RESTORE capable in the root namespace, useful for
recovering files that are unreachable via the file system such as
deleted files, or memfd files.
See corresponding selftest for an example with clone3().
Signed-off-by: Adrian Reber <areber@redhat.com>
Signed-off-by: Nicolas Viennot <Nicolas.Viennot@twosigma.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20200719100418.2112740-2-areber@redhat.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2020-07-19 18:04:11 +08:00
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/* Allow checkpoint/restore related operations */
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/* Allow PID selection during clone3() */
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/* Allow writing to ns_last_pid */
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#define CAP_CHECKPOINT_RESTORE 40
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#define CAP_LAST_CAP CAP_CHECKPOINT_RESTORE
|
2012-10-13 17:46:48 +08:00
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#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
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/*
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* Bit location of each capability (used by user-space library and kernel)
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*/
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#define CAP_TO_INDEX(x) ((x) >> 5) /* 1 << 5 == bits in __u32 */
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#define CAP_TO_MASK(x) (1 << ((x) & 31)) /* mask for indexed __u32 */
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#endif /* _UAPI_LINUX_CAPABILITY_H */
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