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tmpfiles: introduce an explicit line flag $ for enabling purge logic for a line

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Let's make the risk of accidental misuse, and mark lines that shall be
covered by --purge with an explicit new flag "$".

See: #33349
This commit is contained in:
Lennart Poettering 2024-09-12 18:23:06 +02:00
parent 3a41a21666
commit db15657dfb
5 changed files with 48 additions and 7 deletions
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9
NEWS
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@ -2,6 +2,15 @@ systemd System and Service Manager
CHANGES WITH 257 in spe:
Incompatible changes:
* The --purge switch of systemd-tmpfiles (which was added in v256) has
been reworked: it will now only apply to tmpfiles.d/ lines marked
with the new "$" flag. This is an incompatible change, and means any
tmpfiles.d/ files which shall be used together with --purge need to
be updated accordingly. This change has been made to make it harder
to accidentally delete too many files when using --purge incorrectly.
Announcements of Future Feature Removals and Incompatible Changes:
* Support for automatic flushing of the nscd user/group database caches

9
man/systemd-tmpfiles.xml
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@ -152,10 +152,11 @@
<varlistentry>
<term><option>--purge</option></term>
<listitem><para>If this option is passed, all files and directories marked for
<emphasis>creation</emphasis> by the <filename>tmpfiles.d/</filename> files specified on the command
line will be <emphasis>deleted</emphasis>. Specifically, this acts on all files and directories
marked with <varname>f</varname>, <varname>F</varname>, <varname>d</varname>, <varname>D</varname>,
<listitem><para>If this option is passed, all files and directories declared for
<emphasis>creation</emphasis> and marked with the <literal>$</literal> character by the
<filename>tmpfiles.d/</filename> files specified on the command line will be
<emphasis>deleted</emphasis>. Specifically, this acts on all files and directories marked with
<varname>f</varname>, <varname>F</varname>, <varname>d</varname>, <varname>D</varname>,
<varname>v</varname>, <varname>q</varname>, <varname>Q</varname>, <varname>p</varname>,
<varname>L</varname>, <varname>c</varname>, <varname>b</varname>, <varname>C</varname>,
<varname>w</varname>, <varname>e</varname>. If this switch is used at least one

4
man/tmpfiles.d.xml
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@ -539,6 +539,10 @@ w- /proc/sys/vm/swappiness - - - - 10</programlisting></para>
service, the line is silently skipped. If <literal>^</literal> and <literal>~</literal> are combined
Base64 decoding is applied to the credential contents.</para>
<para>If the dollar sign (<literal>$</literal>) is used, the file becomes subject to removal when
<command>systemd-tmpfiles</command> is invoked with the <option>--purge</option> switch. Lines without
this character are unaffected by that switch.</para>
<para>Note that for all line types that result in creation of any kind of file node
(i.e. <varname>f</varname>,
<varname>d</varname>/<varname>D</varname>/<varname>v</varname>/<varname>q</varname>/<varname>Q</varname>,

16
src/tmpfiles/tmpfiles.c
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@ -170,6 +170,8 @@ typedef struct Item {
bool try_replace:1;
bool purge:1;
OperationMask done;
} Item;
@ -3046,6 +3048,9 @@ static int purge_item(Context *c, Item *i) {
if (!needs_purge(i->type))
return 0;
if (!i->purge)
return 0;
log_debug("Running purge action for entry %c %s", (char) i->type, i->path);
if (needs_glob(i->type))
@ -3602,7 +3607,7 @@ static int parse_line(
ItemArray *existing;
OrderedHashmap *h;
bool append_or_force = false, boot = false, allow_failure = false, try_replace = false,
unbase64 = false, from_cred = false, missing_user_or_group = false;
unbase64 = false, from_cred = false, missing_user_or_group = false, purge = false;
int r;
assert(fname);
@ -3668,6 +3673,8 @@ static int parse_line(
unbase64 = true;
else if (action[pos] == '^' && !from_cred)
from_cred = true;
else if (action[pos] == '$' && !purge)
purge = true;
else {
*invalid_config = true;
return log_syntax(NULL, LOG_ERR, fname, line, SYNTHETIC_ERRNO(EBADMSG),
@ -3684,6 +3691,7 @@ static int parse_line(
i.append_or_force = append_or_force;
i.allow_failure = allow_failure;
i.try_replace = try_replace;
i.purge = purge;
r = specifier_printf(path, PATH_MAX-1, specifier_table, arg_root, NULL, &i.path);
if (ERRNO_IS_NOINFO(r))
@ -3838,6 +3846,12 @@ static int parse_line(
"Unknown command type '%c'.", (char) i.type);
}
if (i.purge && !needs_purge(i.type)) {
*invalid_config = true;
return log_syntax(NULL, LOG_ERR, fname, line, SYNTHETIC_ERRNO(EBADMSG),
"Purge flag '$' combined with line type '%c' which does not support purging.", (char) i.type);
}
if (!should_include_path(i.path))
return 0;

17
test/units/TEST-22-TMPFILES.18.sh
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@ -9,26 +9,39 @@ set -o pipefail
export SYSTEMD_LOG_LEVEL=debug
c='
d /tmp/somedir
f /tmp/somedir/somefile - - - - baz
d$ /tmp/somedir
f$ /tmp/somedir/somefile - - - - baz
f /tmp/someotherfile - - - - qux
'
systemd-tmpfiles --create - <<<"$c"
test -f /tmp/somedir/somefile
grep -q baz /tmp/somedir/somefile
grep -q qux /tmp/someotherfile
systemd-tmpfiles --purge --dry-run - <<<"$c"
test -f /tmp/somedir/somefile
grep -q baz /tmp/somedir/somefile
grep -q qux /tmp/someotherfile
systemd-tmpfiles --purge - <<<"$c"
test ! -f /tmp/somedir/somefile
test ! -d /tmp/somedir/
grep -q qux /tmp/someotherfile
systemd-tmpfiles --create --purge --dry-run - <<<"$c"
test ! -f /tmp/somedir/somefile
test ! -d /tmp/somedir/
grep -q qux /tmp/someotherfile
systemd-tmpfiles --create --purge - <<<"$c"
test -f /tmp/somedir/somefile
grep -q baz /tmp/somedir/somefile
grep -q qux /tmp/someotherfile
systemd-tmpfiles --purge - <<<"$c"
test ! -f /tmp/somedir/somefile
test ! -d /tmp/somedir/
grep -q qux /tmp/someotherfile
rm /tmp/someotherfile