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shared/install: also check for self-aliases during installation and ignore them

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We had a check that was done in unit_file_resolve_symlink(). Let's move
the check to unit_validate_alias_symlink_or_warn(), which makes it available
to the code in install.c.

With this, unit_file_resolve_symlink() behaves almost the same. The warning
about "suspicious symlink" is done a bit later. I think this should be OK.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2022-03-10 20:26:59 +01:00
parent 99aad9a2b9
commit f663e6468f
3 changed files with 21 additions and 20 deletions
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26
src/basic/unit-file.c
View File

@ -82,7 +82,8 @@ int unit_validate_alias_symlink_or_warn(int log_level, const char *filename, con
*
* -EINVAL is returned if the something is wrong with the source filename or the source unit type is
* not allowed to symlink,
* -EXDEV if the target filename is not a valid unit name or doesn't match the source.
* -EXDEV if the target filename is not a valid unit name or doesn't match the source,
* -ELOOP for an alias to self.
*/
src = basename(filename);
@ -111,6 +112,11 @@ int unit_validate_alias_symlink_or_warn(int log_level, const char *filename, con
/* dst checks */
if (streq(src, dst))
return log_debug_errno(SYNTHETIC_ERRNO(ELOOP),
"%s: unit self-alias: %s → %s, ignoring.",
filename, src, dst);
dst_name_type = unit_name_to_instance(dst, &dst_instance);
if (dst_name_type < 0)
return log_full_errno(log_level, dst_name_type == -EINVAL ? SYNTHETIC_ERRNO(EXDEV) : dst_name_type,
@ -347,24 +353,12 @@ int unit_file_resolve_symlink(
if (r < 0)
return r;
bool self_alias = streq(target_name, filename);
if (is_path(tail))
log_full(self_alias ? LOG_DEBUG : LOG_WARNING,
"Suspicious symlink %s/%s→%s, treating as alias.",
dir, filename, simplified);
r = unit_validate_alias_symlink_or_warn(LOG_NOTICE, filename, simplified);
if (r < 0)
return r;
if (self_alias && !resolve_destination_target)
/* A self-alias that has no effect when loading, let's just ignore it. */
return log_debug_errno(SYNTHETIC_ERRNO(ELOOP),
"Unit file self-alias: %s/%s → %s, ignoring.",
dir, filename, target_name);
log_debug("Unit file alias: %s/%s → %s", dir, filename, target_name);
if (is_path(tail))
log_warning("Suspicious symlink %s/%s→%s, treating as alias.",
dir, filename, simplified);
dst = resolve_destination_target ? TAKE_PTR(simplified) : TAKE_PTR(target_name);
}

9
src/shared/install.c
View File

@ -1695,6 +1695,11 @@ int unit_file_verify_alias(
* ret_dst is set in cases where "instance propagation" happens, i.e. when the instance part is
* inserted into dst. It is not normally set, even on success, so that the caller can easily
* distinguish the case where instance propagation occurred.
*
* Returns:
* -EXDEV when the alias doesn't match the unit,
* -EUCLEAN when the name is invalid,
* -ELOOP when the alias it to the unit itself.
*/
const char *path_alias = strrchr(dst, '/');
@ -1760,6 +1765,8 @@ int unit_file_verify_alias(
}
r = unit_validate_alias_symlink_or_warn(LOG_DEBUG, dst_updated ?: dst, info->name);
if (r == -ELOOP) /* -ELOOP means self-alias, which we (quietly) ignore */
return r;
if (r < 0) {
unit_file_changes_add(changes, n_changes,
r == -EINVAL ? -EXDEV : r,
@ -1799,6 +1806,8 @@ static int install_info_symlink_alias(
}
q = unit_file_verify_alias(info, dst, &dst_updated, changes, n_changes);
if (q == -ELOOP)
continue;
if (q < 0) {
r = r < 0 ? r : q;
continue;

6
test/test-systemctl-enable.sh
View File

@ -328,8 +328,7 @@ test ! -h "$root/etc/systemd/system/services.target.wants/templ1@two.service"
test ! -e "$root/etc/systemd/system/link4.service"
cat >"$root/etc/systemd/system/link4.service" <<EOF
[Install]
# FIXME: self-alias should be ignored
# Alias=link4.service
Alias=link4.service
Alias=link4@.service
Alias=link4@inst.service
Alias=link4alias.service
@ -372,8 +371,7 @@ test ! -h "$root/etc/systemd/system/link4alias2.service"
test ! -e "$root/etc/systemd/system/link5.service"
cat >"$root/etc/systemd/system/link5.service" <<EOF
[Install]
# FIXME: self-alias should be ignored
# Alias=link5.service
Alias=link5.service
Alias=link5alias.service
Alias=link5alias2.service
EOF