[PATCH v3 09/24] powerpc/secvar: Warn when PAGE_SIZE is smaller than max object size
From: Andrew Donnellan <hidden>
Date: 2023-01-18 06:32:00
Also in:
linux-integrity, lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
Due to sysfs constraints, when writing to a variable, we can only handle writes of up to PAGE_SIZE. It's possible that the maximum object size is larger than PAGE_SIZE, in which case, print a warning on boot so that the user is aware. Signed-off-by: Andrew Donnellan <redacted> Signed-off-by: Russell Currey <redacted> --- v3: New patch (ajd) --- arch/powerpc/kernel/secvar-sysfs.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/arch/powerpc/kernel/secvar-sysfs.c b/arch/powerpc/kernel/secvar-sysfs.c
index d9352d4be87b..68fb0b857442 100644
--- a/arch/powerpc/kernel/secvar-sysfs.c
+++ b/arch/powerpc/kernel/secvar-sysfs.c@@ -217,6 +217,7 @@ static int secvar_sysfs_load_static(void) static int secvar_sysfs_init(void) { + u64 max_size; int rc; if (!secvar_ops) {
@@ -266,6 +267,14 @@ static int secvar_sysfs_init(void) goto err; } + // Due to sysfs limitations, we will only ever get a write buffer of + // up to 1 page in size. Print a warning if this is potentially going + // to cause problems, so that the user is aware. + secvar_ops->max_size(&max_size); + if (max_size > PAGE_SIZE) + pr_warn_ratelimited("PAGE_SIZE (%lu) is smaller than maximum object size (%llu), writes are limited to PAGE_SIZE\n", + PAGE_SIZE, max_size); + return 0; err: kobject_put(secvar_kobj);
--
2.39.0