LSM: Better reporting of actual LSMs at boot

PATCH In review Kees Cook 5 participants 5 messages Nov 2, 2022 – Nov 16, 2022

Subsystems (2)

BPF Security (LSM)

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Kees Cook

author

2022-11-02 00:05 UTC #0 lore raw

PATCH v2 1/1 LSM: Better reporting of actual LSMs at boot

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 <[email protected]>

Cc James Morris <[email protected]>

Cc "Serge E. Hallyn" <[email protected]>

Cc [email protected]

Signed-off-by Kees Cook <[email protected]>

---
v2: en/dis-enabled expanded, example output in commit log, use pr_cont.
v1: https://lore.kernel.org/lkml/[email protected]/

---
 security/security.c | 45 ++++++++++++++++++++++++++++++++++++---------
 1 file changed, 36 insertions(+), 9 deletions(-)

security/security.c +36 -9

index 79d82cb6e469..abceabda103d 100644
@@ -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);
 	}

Signature · 1 line

2.34.1

Casey Schaufler

Acked-by on v2 1/1

2022-11-02 00:47 UTC #1 lore raw

Quoted 124 lines · Kees Cook

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

Quoted 5 lines

Cc Paul Moore <[email protected]>
Cc James Morris <[email protected]>
Cc "Serge E. Hallyn" <[email protected]>
Cc [email protected]
Signed-off-by Kees Cook <[email protected]>

Acked-by Casey Schaufler <[email protected]>

I'm curious about what is driving this change.

Quoted 132 lines

---
v2: en/dis-enabled expanded, example output in commit log, use pr_cont.
v1: https://lore.kernel.org/lkml/[email protected]/

---
 security/security.c | 45 ++++++++++++++++++++++++++++++++++++---------
 1 file changed, 36 insertions(+), 9 deletions(-)

security/security.c +36 -9

index 79d82cb6e469..abceabda103d 100644
@@ -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);
 	}

Kees Cook

2022-11-02 00:53 UTC #2 lore raw

Quoted 5 lines · Casey Schaufler

Quoted 1 line · Kees Cook
Enhance the details reported by "lsm.debug" in several ways:
[...]
Acked-by Casey Schaufler <[email protected]>

Thanks!

Quoted 1 line

I'm curious about what is driving this change.

I was working on the ima stacking PoC and found the lsm.debug output confusing to read, and I wrote it. :P So, I wanted to clarify things and make sure stuff like lockdown was visible. Additionally, if we're going to keep the "lsm=" param as-is, I wanted it's value visible at boot so people would know what to start from when making changes.

-Kees

Signature · 1 line

Kees Cook

Mickaël Salaün

Acked-by on v2 1/1

2022-11-03 16:10 UTC #3 lore raw

In reply to Kees Cook

Quoted 124 lines · Kees Cook

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

Quoted 5 lines

Cc Paul Moore <[email protected]>
Cc James Morris <[email protected]>
Cc "Serge E. Hallyn" <[email protected]>
Cc [email protected]
Signed-off-by Kees Cook <[email protected]>

I think this change would be useful to help users debug their LSM configuration. I'm not sure about the whitespace-aligned output though, I guess it could break some scripts, but it is not part of the ABI and only relevant for debug purpose.

Acked-by Mickaël Salaün <[email protected]>

Quoted 132 lines

---
v2: en/dis-enabled expanded, example output in commit log, use pr_cont.
v1: https://lore.kernel.org/lkml/[email protected]/

---
  security/security.c | 45 ++++++++++++++++++++++++++++++++++++---------
  1 file changed, 36 insertions(+), 9 deletions(-)

security/security.c +36 -9

index 79d82cb6e469..abceabda103d 100644
@@ -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);
  	}

Paul Moore

maintainer

2022-11-16 23:04 UTC #4 lore raw

In reply to Kees Cook

Quoted 130 lines · Kees Cook

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 <[email protected]>
Cc James Morris <[email protected]>
Cc "Serge E. Hallyn" <[email protected]>
Cc [email protected]
Signed-off-by Kees Cook <[email protected]>

Quoted 6 lines

---
v2: en/dis-enabled expanded, example output in commit log, use pr_cont.
v1: https://lore.kernel.org/lkml/[email protected]/
---
 security/security.c | 45 ++++++++++++++++++++++++++++++++++++---------
 1 file changed, 36 insertions(+), 9 deletions(-)

I tend to agree with Mickaël regarding the aligned output, but that's not worth worrying too much about for debug stuff. Merged into lsm/next, thanks Kees.

Signature · 1 line

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