This patch implements the new magic character '!'. By putting '!' in front
of a command, systemd executes it with full privileges ignoring paramters
such as User, Group, SupplementaryGroups, CapabilityBoundingSet,
AmbientCapabilities, SecureBits, SystemCallFilter, SELinuxContext,
AppArmorProfile, SmackProcessLabel, and RestrictAddressFamilies.
Fixes partially https://github.com/systemd/systemd/issues/3414
Related to https://github.com/coreos/rkt/issues/2482
Testing:
1. Create a user 'bob'
2. Create the unit file /etc/systemd/system/exec-perm.service
(You can use the example below)
3. sudo systemctl start ext-perm.service
4. Verify that the commands starting with '!' were not executed as bob,
4.1 Looking to the output of ls -l /tmp/exec-perm
4.2 Each file contains the result of the id command.
`````````````````````````````````````````````````````````````````
[Unit]
Description=ext-perm
[Service]
Type=oneshot
TimeoutStartSec=0
User=bob
ExecStartPre=!/usr/bin/sh -c "/usr/bin/rm /tmp/exec-perm*" ;
/usr/bin/sh -c "/usr/bin/id > /tmp/exec-perm-start-pre"
ExecStart=/usr/bin/sh -c "/usr/bin/id > /tmp/exec-perm-start" ;
!/usr/bin/sh -c "/usr/bin/id > /tmp/exec-perm-star-2"
ExecStartPost=/usr/bin/sh -c "/usr/bin/id > /tmp/exec-perm-start-post"
ExecReload=/usr/bin/sh -c "/usr/bin/id > /tmp/exec-perm-reload"
ExecStop=!/usr/bin/sh -c "/usr/bin/id > /tmp/exec-perm-stop"
ExecStopPost=/usr/bin/sh -c "/usr/bin/id > /tmp/exec-perm-stop-post"
[Install]
WantedBy=multi-user.target]
`````````````````````````````````````````````````````````````````
Let's add an extra safety check before we chmod/chown a TTY to the right user,
as we might end up having connected something to STDIN/STDOUT that is actually
not a TTY, even though this might have been requested, due to permissive
StandardInput= settings or transient service activation with fds passed in.
Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=85255
New exec boolean MemoryDenyWriteExecute, when set, installs
a seccomp filter to reject mmap(2) with PAGE_WRITE|PAGE_EXEC
and mprotect(2) with PAGE_EXEC.
The macro determines the right length of a AF_UNIX "struct sockaddr_un" to pass to
connect() or bind(). It automatically figures out if the socket refers to an
abstract namespace socket, or a socket in the file system, and properly handles
the full length of the path field.
This macro is not only safer, but also simpler to use, than the usual
offsetof() + strlen() logic.
The manpage of seccomp specify that using seccomp with
SECCOMP_SET_MODE_FILTER will return EACCES if the caller do not have
CAP_SYS_ADMIN set, or if the no_new_privileges bit is not set. Hence,
without NoNewPrivilege set, it is impossible to use a SystemCall*
directive with a User directive set in system mode.
Now, NoNewPrivileges is set if we are in user mode, or if we are in
system mode and we don't have CAP_SYS_ADMIN, and SystemCall*
directives are used.
Throughout the tree there's spurious use of spaces separating ++ and --
operators from their respective operands. Make ++ and -- operator
consistent with the majority of existing uses; discard the spaces.
The setting is hardly useful (since its effect is generally reduced to zero due
to file system caps), and with the advent of ambient caps an actually useful
replacement exists, hence let's get rid of this.
I am pretty sure this was unused and our man page already recommended against
its use, hence this should be a safe thing to remove.
Assign errno-style errors to a variable called "r" when they happen, the same way we do this in most other calls. It's
bad enough that the error handling part of the function deals with two different error variables (pam_code and r) now,
but before this fix it was even three!
gcc is confused by the common idiom of
return errno ? -errno : -ESOMETHING
and thinks a positive value may be returned. Replace this condition
with errno > 0 to help gcc and avoid many spurious warnings. I filed
a gcc rfe a long time ago, but it hard to say if it will ever be
implemented [1].
Both conventions were used in the codebase, this change makes things
more consistent. This is a follow up to bcb161b023.
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61846
This patch adds support for ambient capabilities in service files. The
idea with ambient capabilities is that the execed processes can run with
non-root user and get some inherited capabilities, without having any
need to add the capabilities to the executable file.
You need at least Linux 4.3 to use ambient capabilities. SecureBit
keep-caps is automatically added when you use ambient capabilities and
wish to change the user.
An example system service file might look like this:
[Unit]
Description=Service for testing caps
[Service]
ExecStart=/usr/bin/sleep 10000
User=nobody
AmbientCapabilities=CAP_NET_ADMIN CAP_NET_RAW
After starting the service it has these capabilities:
CapInh: 0000000000003000
CapPrm: 0000000000003000
CapEff: 0000000000003000
CapBnd: 0000003fffffffff
CapAmb: 0000000000003000
Change the capability bounding set parser and logic so that the bounding
set is kept as a positive set internally. This means that the set
reflects those capabilities that we want to keep instead of drop.
If pid < 0 after fork(), 0 is always returned because r =
exec_context_load_environment() has exited successfully.
This will make the caller of exec_spawn() not able to handle
the fork() error case and make systemd abort assert() possibly.
This directive allows passing environment variables from the system
manager to spawned services. Variables in the system manager can be set
inside a container by passing `--set-env=...` options to systemd-spawn.
Tested with an on-disk test.service unit. Tested using multiple variable
names on a single line, with an empty setting to clear the current list
of variables, with non-existing variables.
Tested using `systemd-run -p PassEnvironment=VARNAME` to confirm it
works with transient units.
Confirmed that `systemctl show` will display the PassEnvironment
settings.
Checked that man pages are generated correctly.
No regressions in `make check`.
The files are named too generically, so that they might conflict with
the upstream project headers. Hence, let's add a "-util" suffix, to
clarify that this are just our utility headers and not any official
upstream headers.
There are more than enough calls doing string manipulations to deserve
its own files, hence do something about it.
This patch also sorts the #include blocks of all files that needed to be
updated, according to the sorting suggestions from CODING_STYLE. Since
pretty much every file needs our string manipulation functions this
effectively means that most files have sorted #include blocks now.
Also touches a few unrelated include files.
Before, we'd always reset acquired terminals, which is not really
desired, as we expose a setting TTYReset= which is supposed to control
whether the TTY is reset or not. Previously that setting would only
enable a second resetting of the TTY, which is of course pointless...
Hence, move the implicit resetting out of acquire_terminal() and make
the callers do it if they need it.
When starting a transient service, allow setting stdin/stdout/stderr fds
for it, by passing them in via the bus.
This also simplifies some of the serialization code for units.
This adds support for caching harddisk passwords in the kernel keyring
if it is available, thus supporting caching without Plymouth being
around.
This is also useful for hooking up "gdm-auto-login" with the collected
boot-time harddisk password, in order to support gnome keyring
passphrase unlocking via the HDD password, if it is the same.
Any passwords added to the kernel keyring this way have a timeout of
2.5min at which time they are purged from the kernel.
This adds support for naming file descriptors passed using socket
activation. The names are passed in a new $LISTEN_FDNAMES= environment
variable, that matches the existign $LISTEN_FDS= one and contains a
colon-separated list of names.
This also adds support for naming fds submitted to the per-service fd
store using FDNAME= in the sd_notify() message.
This also adds a new FileDescriptorName= setting for socket unit files
to set the name for fds created by socket units.
This also adds a new call sd_listen_fds_with_names(), that is similar to
sd_listen_fds(), but also returns the names of the fds.
systemd-activate gained the new --fdname= switch to specify a name for
testing socket activation.
This is based on #1247 by Maciej Wereski.
Fixes#1247.
If set to ~ the working directory is set to the home directory of the
user configured in User=.
This change also exposes the existing switch for the working directory
that allowed making missing working directories non-fatal.
This also changes "machinectl shell" to make use of this to ensure that
the invoked shell is by default in the user's home directory.
Fixes#1268.
This cleans up exec_child() function by moving mac_smack_apply_pid()
and setup_pam() to the same condition block, since both of them have
the same condition (i.e params->apply_permissions). It improves
readability without changing its operation.
When 'SmackProcessLabel=' is used in user@.service file, all processes
launched in systemd user session should be labeled as the designated name
of 'SmackProcessLabel' directive. However, if systemd has its own smack
label using '--with-smack-run-label' configuration, '(sd-pam)' is
labeled as the specific name of '--with-smack-run-label'. If
'SmackProcessLabel=' is used in user@.service file without
'--with-smack-run-label' configuration, (sd-pam) is labeled as "_" since
systemd (i.e. pid=1) is labeled as "_".
This is mainly because setup_pam() function is called before applying
smack label to child process. This patch fixes it by calling setup_pam()
after setting the smack label.
If we spawn a unit with a non-empty 'PAMName=', we fork off a
child-process _inside_ the unit, known as '(sd-pam)', which watches the
session. It waits for the main-process to exit and then finishes it via
pam_close_session(3).
However, the '(sd-pam)' setup is highly asynchronous. There is no
guarantee that process gets spawned before we finish the unit setup.
Therefore, there might be a root-owned process inside of the cgroup of
the unit, thus causing cg_migrate() to error-out with EPERM.
This patch makes setup_pam() synchronous and waits for the '(sd-pam)'
setup to finish before continuing. This guarantees that setresuid(2) was
at least tried before we continue with the child setup of the real unit.
Note that if setresuid(2) fails, we already warn loudly about it. You
really must make sure that you own the passed user if using 'PAMName='.
It seems very plausible to rely on that assumption.
When Group is set in the unit, the runtime directories are owned by
this group and not the default group of the user (same for cgroup paths
and standard outputs)
Fix#1231
