[PATCH v5 02/25] powerpc/pseries: Fix alignment of PLPKS structures and buffers
From: Andrew Donnellan <hidden>
Date: 2023-01-31 06:40:42
Also in:
linux-integrity, lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
A number of structures and buffers passed to PKS hcalls have alignment
requirements, which could on occasion cause problems:
- Authorisation structures must be 16-byte aligned and must not cross a
page boundary
- Label structures must not cross page boundaries
- Password output buffers must not cross page boundaries
To ensure correct alignment, we adjust the allocation size of each of
these structures/buffers to be the closest power of 2 that is at least the
size of the structure/buffer (since kmalloc() guarantees that an
allocation of a power of 2 size will be aligned to at least that size).
Reported-by: Benjamin Gray <redacted>
Fixes: 2454a7af0f2a ("powerpc/pseries: define driver for Platform KeyStore")
Signed-off-by: Andrew Donnellan <redacted>
Reviewed-by: Russell Currey <redacted>
Signed-off-by: Russell Currey <redacted>
---
v3: Merge plpks fixes and signed update series with secvar series
v4: Fix typo in commit message
Move up in series (npiggin)
v5: Reword commit message to better explain alignment guarantee (mpe)
---
arch/powerpc/platforms/pseries/plpks.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/plpks.c b/arch/powerpc/platforms/pseries/plpks.c
index 9e85b6d85b0b..a01cf2ff140a 100644
--- a/arch/powerpc/platforms/pseries/plpks.c
+++ b/arch/powerpc/platforms/pseries/plpks.c@@ -126,7 +126,8 @@ static int plpks_gen_password(void) u8 *password, consumer = PKS_OS_OWNER; int rc; - password = kzalloc(maxpwsize, GFP_KERNEL); + // The password must not cross a page boundary, so we align to the next power of 2 + password = kzalloc(roundup_pow_of_two(maxpwsize), GFP_KERNEL); if (!password) return -ENOMEM;
@@ -162,7 +163,9 @@ static struct plpks_auth *construct_auth(u8 consumer) if (consumer > PKS_OS_OWNER) return ERR_PTR(-EINVAL); - auth = kzalloc(struct_size(auth, password, maxpwsize), GFP_KERNEL); + // The auth structure must not cross a page boundary and must be + // 16 byte aligned. We align to the next largest power of 2 + auth = kzalloc(roundup_pow_of_two(struct_size(auth, password, maxpwsize)), GFP_KERNEL); if (!auth) return ERR_PTR(-ENOMEM);
@@ -196,7 +199,8 @@ static struct label *construct_label(char *component, u8 varos, u8 *name, if (component && slen > sizeof(label->attr.prefix)) return ERR_PTR(-EINVAL); - label = kzalloc(sizeof(*label), GFP_KERNEL); + // The label structure must not cross a page boundary, so we align to the next power of 2 + label = kzalloc(roundup_pow_of_two(sizeof(*label)), GFP_KERNEL); if (!label) return ERR_PTR(-ENOMEM);
--
2.39.1