I can't think of any real vulnerability about this, but it still feels
better to check a variable with "secure" in its name with
secure_getenv() rather than plain getenv().
Paranoia FTW!
The variable is renamed to SYSTEMD_PAGERSECURE (because it's not just about
less now), and we automatically enable secure mode in certain cases, but not
otherwise.
This approach is more nuanced, but should provide a better experience for
users:
- Previusly we would set LESSSECURE=1 and trust the pager to make use of
it. But this has an effect only on less. We need to not start pagers which
are insecure when in secure mode. In particular more is like that and is a
very popular pager.
- We don't enable secure mode always, which means that those other pagers can
reasonably used.
- We do the right thing by default, but the user has ultimate control by
setting SYSTEMD_PAGERSECURE.
Fixes#5666.
v2:
- also check $PKEXEC_UID
v3:
- use 'sd_pid_get_owner_uid() != geteuid()' as the condition
Some extra safety when invoked via "sudo". With this we address a
genuine design flaw of sudo, and we shouldn't need to deal with this.
But it's still a good idea to disable this surface given how exotic it
is.
Prompted by #5666
"less" doesn't properly reset its terminal on SIGTERM, it does so only
on SIGINT. Let's thus configure SIGINT instead of SIGTERM.
I think this is something less should fix too, and clean up things
correctly on SIGTERM, too. However, given that we explicitly enable
SIGINT behaviour by passing "K" to $LESS I figure it makes sense if we
also send SIGINT instead of SIGTERM to match it.
Fixes: #16084
The parent is waiting for an EOF on the pipe transmitting the pager name
before starting to send data. With external pagers this happens due to
execlp() CLOEXEC'ing the pipe, so the internal pager needs to close it
manually.
The code so far logged about some errors but was silent on others. Let's
stream-line that and make the function fully self-logging on all error
conditions.
Similar to the previous commit: in many cases no further fd processing
needs to be done in forked of children before execve() or any of its
flavours are called. In those case we can use FORK_RLIMIT_NOFILE_SAFE
instead.
Whenever we invoke external, foreign code from code that has
RLIMIT_NOFILE's soft limit bumped to high values, revert it to 1024
first. This is a safety precaution for compatibility with programs using
select() which cannot operate with fds > 1024.
This commit adds the call to rlimit_nofile_safe() to all invocations of
exec{v,ve,l}() and friends that either are in code that we know runs
with RLIMIT_NOFILE bumped up (which is PID 1 and all journal code for
starters) or that is part of shared code that might end up there.
The calls are placed as early as we can in processes invoking a flavour
of execve(), but after the last time we do fd manipulations, so that we
can still take benefit of the high fd limits for that.
pager.[ch] doesn't use any APIs from src/libsystemd/ or src/shared/
hence there's no reason for it to be in src/shared/, let's move it to
src/basic/ instead.
This enables us to use pager.[ch] APIs from other code in src/basic/,
for example pager_have() and suchlike.
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.
I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
"noreturn" is reserved and can be used in other header files we include:
[ 16s] In file included from /usr/include/gcrypt.h:30:0,
[ 16s] from ../src/journal/journal-file.h:26,
[ 16s] from ../src/journal/journal-vacuum.c:31:
[ 16s] /usr/include/gpg-error.h:1544:46: error: expected ‘,’ or ‘;’ before ‘)’ token
[ 16s] void gpgrt_log_bug (const char *fmt, ...) GPGRT_ATTR_NR_PRINTF(1,2);
Here we include grcrypt.h (which in turns include gpg-error.h) *after* we
"noreturn" was defined in macro.h.
We maintain static process-wide variables in these subsystems without
locking, hence let's refuse operation unless we are called from the main
thread (which we do anyway) just as a safety precaution.
Using wait_for_terminate_and_check() instead of wait_for_terminate()
let's us simplify, shorten and unify the return value checking and
logging of waitid(). Hence, let's use it all over the place.
This adds a new safe_fork() wrapper around fork() and makes use of it
everywhere. The new wrapper does a couple of things we previously did
manually and separately in a safer, more correct and automatic way:
1. Optionally resets signal handlers/mask in the child
2. Sets a name on all processes we fork off right after forking off (and
the patch assigns useful names for all processes we fork off now,
following a systematic naming scheme: always enclosed in () – in order
to indicate that these are not proper, exec()ed processes, but only
forked off children, and if the process is long-running with only our
own code, without execve()'ing something else, it gets am "sd-" prefix.)
3. Optionally closes all file descriptors in the child
4. Optionally sets a PR_SET_DEATHSIG to SIGTERM in the child, in a safe
way so that the parent dying before this happens being handled
safely.
5. Optionally reopens the logs
6. Optionally connects stdin/stdout/stderr to /dev/null
7. Debug logs about the forked off processes.
We make copies (without O_CLOEXEC) of the fds anyway before using them,
hence let's be safe and create them with O_CLOEXEC first, so that we
don't run into issues should pager_open() be called in a threaded
environment where another thread fork()s at the wrong time and ends up
with fds not marked O_CLOEXEC.
This moves pretty much all uses of getpid() over to getpid_raw(). I
didn't specifically check whether the optimization is worth it for each
replacement, but in order to keep things simple and systematic I
switched over everything at once.
This adds a unified "copy_flags" parameter to all copy_xyz() function
calls, replacing the various boolean flags so far used. This should make
many invocations more readable as it is clear what behaviour is
precisely requested. This also prepares ground for adding support for
more modes later on.
Many subsystems define own pager_open_if_enabled() function which
checks '--no-pager' command line argument and open pager depends
on its value. All implementations of pager_open_if_enabled() are
the same. Let's merger this function with pager_open() from the
shared/pager.c and remove pager_open_if_enabled() from all subsytems
to prevent code duplication.
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.
off_t is a really weird type as it is usually 64bit these days (at least
in sane programs), but could theoretically be 32bit. We don't support
off_t as 32bit builds though, but still constantly deal with safely
converting from off_t to other types and back for no point.
Hence, never use the type anymore. Always use uint64_t instead. This has
various benefits, including that we can expose these values directly as
D-Bus properties, and also that the values parse the same in all cases.
Turns this:
r = -errno;
log_error_errno(errno, "foo");
into this:
r = log_error_errno(errno, "foo");
and this:
r = log_error_errno(errno, "foo");
return r;
into this:
return log_error_errno(errno, "foo");
This way we can be sure that less has the same idea of the terminal as
we do.
This solves issues in systems that have locale uninitalized, where
systemd would output UTF-8 but less wouldn't allow it and show them as
control characters.
It's really confusing if stdout goes to the pager, but stderr is written
directly to the screen. Hence, make sure both stdout and stderr are
passed to the pager when doing autopaging.
Zbigniew Jędrzejewski-Szmek