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Message-Id: <20221018064825.never.323-kees@kernel.org>
Date: Mon, 17 Oct 2022 23:48:41 -0700
From: Kees Cook <keescook@...omium.org>
To: Paul Moore <paul@...l-moore.com>
Cc: Kees Cook <keescook@...omium.org>,
James Morris <jmorris@...ei.org>,
"Serge E. Hallyn" <serge@...lyn.com>,
linux-security-module@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: [PATCH] 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.
Cc: Paul Moore <paul@...l-moore.com>
Cc: James Morris <jmorris@...ei.org>
Cc: "Serge E. Hallyn" <serge@...lyn.com>
Cc: linux-security-module@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
security/security.c | 61 +++++++++++++++++++++++++++++++++++++++------
1 file changed, 54 insertions(+), 7 deletions(-)
diff --git a/security/security.c b/security/security.c
index 9696dd64095e..6f6079dec270 100644
--- a/security/security.c
+++ b/security/security.c
@@ -159,7 +159,7 @@ 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,
+ init_debug("%s ordered: %s (%sabled)\n", from, lsm->name,
is_enabled(lsm) ? "en" : "dis");
}
@@ -222,7 +222,7 @@ 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);
@@ -250,7 +250,7 @@ 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. */
@@ -289,7 +289,8 @@ 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. */
@@ -307,7 +308,8 @@ 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);
@@ -318,6 +320,44 @@ 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;
+ size_t size = 0;
+ char *effective, *step, *end;
+
+ /* Count the length of each enabled LSM name. */
+ for (early = __start_early_lsm_info; early < __end_early_lsm_info; early++)
+ if (is_enabled(early))
+ size += strlen(early->name) + 1;
+ for (lsm = ordered_lsms; *lsm; lsm++)
+ if (is_enabled(*lsm))
+ size += strlen((*lsm)->name) + 1;
+
+ /* Allocate space with trailing %NUL or give up. */
+ size += 1;
+ effective = kzalloc(size, GFP_KERNEL);
+ if (!effective)
+ return;
+ end = effective + size;
+ step = effective;
+
+ /* Append each enabled LSM name. */
+ for (early = __start_early_lsm_info; early < __end_early_lsm_info; early++)
+ if (is_enabled(early))
+ step += scnprintf(step, end - step, "%s%s",
+ step == effective ? "" : ",",
+ early->name);
+ for (lsm = ordered_lsms; *lsm; lsm++)
+ if (is_enabled(*lsm))
+ step += scnprintf(step, end - step, "%s%s",
+ step == effective ? "" : ",",
+ (*lsm)->name);
+
+ pr_info("initializing lsm=%s\n", effective);
+ kfree(effective);
+}
+
static void __init ordered_lsm_init(void)
{
struct lsm_info **lsm;
@@ -327,7 +367,8 @@ 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");
@@ -337,6 +378,8 @@ 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);
@@ -393,13 +436,17 @@ 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 (%sabled)\n", lsm->name,
+ is_enabled(lsm) ? "en" : "dis");
if (lsm->enabled)
lsm_append(lsm->name, &lsm_names);
}
--
2.34.1
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