[PATCH v2] LSM: Better reporting of actual LSMs at boot
Kees Cook
keescook at chromium.org
Wed Nov 2 00:05:29 UTC 2022
Enhance the details reported by "lsm.debug" in several ways:
- report contents of "security="
- report contents of "CONFIG_LSM"
- report contents of "lsm="
- report any early LSM details
- whitespace-align the output of similar phases for easier visual parsing
- change "disabled" to more accurate "skipped"
- explain what "skipped" and "ignored" mean in a parenthetical
Upgrade the "security= is ignored" warning from pr_info to pr_warn,
and include full arguments list to make the cause even more clear.
Replace static "Security Framework initializing" pr_info with specific
list of the resulting order of enabled LSMs.
For example, if the kernel is built with:
CONFIG_SECURITY_SELINUX=y
CONFIG_SECURITY_APPARMOR=y
CONFIG_SECURITY_LOADPIN=y
CONFIG_SECURITY_YAMA=y
CONFIG_SECURITY_SAFESETID=y
CONFIG_SECURITY_LOCKDOWN_LSM=y
CONFIG_SECURITY_LANDLOCK=y
CONFIG_INTEGRITY=y
CONFIG_BPF_LSM=y
CONFIG_DEFAULT_SECURITY_APPARMOR=y
CONFIG_LSM="landlock,lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor,bpf"
Booting without options will show:
LSM: initializing lsm=lockdown,capability,landlock,yama,loadpin,safesetid,integrity,selinux,bpf
landlock: Up and running.
Yama: becoming mindful.
LoadPin: ready to pin (currently not enforcing)
SELinux: Initializing.
LSM support for eBPF active
Boot with "lsm.debug" will show:
LSM: legacy security= *unspecified*
LSM: CONFIG_LSM=landlock,lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor,bpf
LSM: boot arg lsm= *unspecified*
LSM: early started: lockdown (enabled)
LSM: first ordered: capability (enabled)
LSM: builtin ordered: landlock (enabled)
LSM: builtin ignored: lockdown (not built into kernel)
LSM: builtin ordered: yama (enabled)
LSM: builtin ordered: loadpin (enabled)
LSM: builtin ordered: safesetid (enabled)
LSM: builtin ordered: integrity (enabled)
LSM: builtin ordered: selinux (enabled)
LSM: builtin ignored: smack (not built into kernel)
LSM: builtin ignored: tomoyo (not built into kernel)
LSM: builtin ordered: apparmor (enabled)
LSM: builtin ordered: bpf (enabled)
LSM: exclusive chosen: selinux
LSM: exclusive disabled: apparmor
LSM: initializing lsm=lockdown,capability,landlock,yama,loadpin,safesetid,integrity,selinux,bpf
LSM: cred blob size = 32
LSM: file blob size = 16
LSM: inode blob size = 72
LSM: ipc blob size = 8
LSM: msg_msg blob size = 4
LSM: superblock blob size = 80
LSM: task blob size = 8
LSM: initializing capability
LSM: initializing landlock
landlock: Up and running.
LSM: initializing yama
Yama: becoming mindful.
LSM: initializing loadpin
LoadPin: ready to pin (currently not enforcing)
LSM: initializing safesetid
LSM: initializing integrity
LSM: initializing selinux
SELinux: Initializing.
LSM: initializing bpf
LSM support for eBPF active
And some examples of how the lsm.debug ordering report changes...
With "lsm.debug security=selinux":
LSM: legacy security=selinux
LSM: CONFIG_LSM=landlock,lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor,bpf
LSM: boot arg lsm= *unspecified*
LSM: early started: lockdown (enabled)
LSM: first ordered: capability (enabled)
LSM: security=selinux disabled: apparmor (only one legacy major LSM)
LSM: builtin ordered: landlock (enabled)
LSM: builtin ignored: lockdown (not built into kernel)
LSM: builtin ordered: yama (enabled)
LSM: builtin ordered: loadpin (enabled)
LSM: builtin ordered: safesetid (enabled)
LSM: builtin ordered: integrity (enabled)
LSM: builtin ordered: selinux (enabled)
LSM: builtin ignored: smack (not built into kernel)
LSM: builtin ignored: tomoyo (not built into kernel)
LSM: builtin ordered: apparmor (disabled)
LSM: builtin ordered: bpf (enabled)
LSM: exclusive chosen: selinux
LSM: initializing lsm=lockdown,capability,landlock,yama,loadpin,safesetid,integrity,selinux,bpf
With "lsm.debug lsm=integrity,selinux,loadpin,crabability,bpf,loadpin,loadpin":
LSM: legacy security= *unspecified*
LSM: CONFIG_LSM=landlock,lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor,bpf
LSM: boot arg lsm=integrity,selinux,loadpin,capability,bpf,loadpin,loadpin
LSM: early started: lockdown (enabled)
LSM: first ordered: capability (enabled)
LSM: cmdline ordered: integrity (enabled)
LSM: cmdline ordered: selinux (enabled)
LSM: cmdline ordered: loadpin (enabled)
LSM: cmdline ignored: crabability (not built into kernel)
LSM: cmdline ordered: bpf (enabled)
LSM: cmdline skipped: apparmor (not in requested order)
LSM: cmdline skipped: yama (not in requested order)
LSM: cmdline skipped: safesetid (not in requested order)
LSM: cmdline skipped: landlock (not in requested order)
LSM: exclusive chosen: selinux
LSM: initializing lsm=lockdown,capability,integrity,selinux,loadpin,bpf
Cc: Paul Moore <paul at paul-moore.com>
Cc: James Morris <jmorris at namei.org>
Cc: "Serge E. Hallyn" <serge at hallyn.com>
Cc: linux-security-module at vger.kernel.org
Signed-off-by: Kees Cook <keescook at chromium.org>
---
v2: en/dis-enabled expanded, example output in commit log, use pr_cont.
v1: https://lore.kernel.org/lkml/20221018064825.never.323-kees@kernel.org/
---
security/security.c | 45 ++++++++++++++++++++++++++++++++++++---------
1 file changed, 36 insertions(+), 9 deletions(-)
diff --git a/security/security.c b/security/security.c
index 79d82cb6e469..abceabda103d 100644
--- a/security/security.c
+++ b/security/security.c
@@ -161,8 +161,8 @@ static void __init append_ordered_lsm(struct lsm_info *lsm, const char *from)
lsm->enabled = &lsm_enabled_true;
ordered_lsms[last_lsm++] = lsm;
- init_debug("%s ordering: %s (%sabled)\n", from, lsm->name,
- is_enabled(lsm) ? "en" : "dis");
+ init_debug("%s ordered: %s (%s)\n", from, lsm->name,
+ is_enabled(lsm) ? "enabled" : "disabled");
}
/* Is an LSM allowed to be initialized? */
@@ -224,7 +224,7 @@ static void __init prepare_lsm(struct lsm_info *lsm)
if (enabled) {
if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && !exclusive) {
exclusive = lsm;
- init_debug("exclusive chosen: %s\n", lsm->name);
+ init_debug("exclusive chosen: %s\n", lsm->name);
}
lsm_set_blob_sizes(lsm->blobs);
@@ -252,7 +252,7 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
/* LSM_ORDER_FIRST is always first. */
for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
if (lsm->order == LSM_ORDER_FIRST)
- append_ordered_lsm(lsm, "first");
+ append_ordered_lsm(lsm, " first");
}
/* Process "security=", if given. */
@@ -270,7 +270,7 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
if ((major->flags & LSM_FLAG_LEGACY_MAJOR) &&
strcmp(major->name, chosen_major_lsm) != 0) {
set_enabled(major, false);
- init_debug("security=%s disabled: %s\n",
+ init_debug("security=%s disabled: %s (only one legacy major LSM)\n",
chosen_major_lsm, major->name);
}
}
@@ -291,7 +291,8 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
}
if (!found)
- init_debug("%s ignored: %s\n", origin, name);
+ init_debug("%s ignored: %s (not built into kernel)\n",
+ origin, name);
}
/* Process "security=", if given. */
@@ -309,7 +310,8 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
if (exists_ordered_lsm(lsm))
continue;
set_enabled(lsm, false);
- init_debug("%s disabled: %s\n", origin, lsm->name);
+ init_debug("%s skipped: %s (not in requested order)\n",
+ origin, lsm->name);
}
kfree(sep);
@@ -320,6 +322,24 @@ static void __init lsm_early_task(struct task_struct *task);
static int lsm_append(const char *new, char **result);
+static void __init report_lsm_order(void)
+{
+ struct lsm_info **lsm, *early;
+ int first = 0;
+
+ pr_info("initializing lsm=");
+
+ /* Report each enabled LSM name, comma separated. */
+ for (early = __start_early_lsm_info; early < __end_early_lsm_info; early++)
+ if (is_enabled(early))
+ pr_cont("%s%s", first++ == 0 ? "" : ",", early->name);
+ for (lsm = ordered_lsms; *lsm; lsm++)
+ if (is_enabled(*lsm))
+ pr_cont("%s%s", first++ == 0 ? "" : ",", (*lsm)->name);
+
+ pr_cont("\n");
+}
+
static void __init ordered_lsm_init(void)
{
struct lsm_info **lsm;
@@ -329,7 +349,8 @@ static void __init ordered_lsm_init(void)
if (chosen_lsm_order) {
if (chosen_major_lsm) {
- pr_info("security= is ignored because it is superseded by lsm=\n");
+ pr_warn("security=%s is ignored because it is superseded by lsm=%s\n",
+ chosen_major_lsm, chosen_lsm_order);
chosen_major_lsm = NULL;
}
ordered_lsm_parse(chosen_lsm_order, "cmdline");
@@ -339,6 +360,8 @@ static void __init ordered_lsm_init(void)
for (lsm = ordered_lsms; *lsm; lsm++)
prepare_lsm(*lsm);
+ report_lsm_order();
+
init_debug("cred blob size = %d\n", blob_sizes.lbs_cred);
init_debug("file blob size = %d\n", blob_sizes.lbs_file);
init_debug("inode blob size = %d\n", blob_sizes.lbs_inode);
@@ -395,13 +418,17 @@ int __init security_init(void)
{
struct lsm_info *lsm;
- pr_info("Security Framework initializing\n");
+ init_debug("legacy security=%s\n", chosen_major_lsm ?: " *unspecified*");
+ init_debug(" CONFIG_LSM=%s\n", builtin_lsm_order);
+ init_debug("boot arg lsm=%s\n", chosen_lsm_order ?: " *unspecified*");
/*
* Append the names of the early LSM modules now that kmalloc() is
* available
*/
for (lsm = __start_early_lsm_info; lsm < __end_early_lsm_info; lsm++) {
+ init_debug(" early started: %s (%s)\n", lsm->name,
+ is_enabled(lsm) ? "enabled" : "disabled");
if (lsm->enabled)
lsm_append(lsm->name, &lsm_names);
}
--
2.34.1
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