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[v2,05/25] capability: use vfsuid_t for vfs_caps rootids

Message ID 20240221-idmap-fscap-refactor-v2-5-3039364623bd@kernel.org (mailing list archive)
State New
Headers show
Series fs: use type-safe uid representation for filesystem capabilities | expand

Commit Message

Seth Forshee Feb. 21, 2024, 9:24 p.m. UTC 
The rootid is a kuid_t, but it contains an id which maped into a mount
idmapping, so it is really a vfsuid. This is confusing and creates
potential for misuse of the value, so change it to vfsuid_t.

Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
---
 include/linux/capability.h | 3 ++-
 kernel/auditsc.c           | 5 +++--
 security/commoncap.c       | 2 +-
 3 files changed, 6 insertions(+), 4 deletions(-)

Comments

Christian Brauner Feb. 22, 2024, 2:25 p.m. UTC | #1 
On Wed, Feb 21, 2024 at 03:24:36PM -0600, Seth Forshee (DigitalOcean) wrote:
> The rootid is a kuid_t, but it contains an id which maped into a mount
> idmapping, so it is really a vfsuid. This is confusing and creates
> potential for misuse of the value, so change it to vfsuid_t.
> 
> Acked-by: Paul Moore <paul@paul-moore.com>
> Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
> ---

Looks good,
Reviewed-by: Christian Brauner <brauner@kernel.org>
diff mbox series

Patch

diff --git a/include/linux/capability.h b/include/linux/capability.h
index c24477e660fc..eb46d346bbbc 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -16,6 +16,7 @@ 
 #include <uapi/linux/capability.h>
 #include <linux/uidgid.h>
 #include <linux/bits.h>
+#include <linux/vfsid.h>
 
 #define _KERNEL_CAPABILITY_VERSION _LINUX_CAPABILITY_VERSION_3
 
@@ -26,7 +27,7 @@  typedef struct { u64 val; } kernel_cap_t;
 /* same as vfs_ns_cap_data but in cpu endian and always filled completely */
 struct vfs_caps {
 	__u32 magic_etc;
-	kuid_t rootid;
+	vfsuid_t rootid;
 	kernel_cap_t permitted;
 	kernel_cap_t inheritable;
 };
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 783d0bf69ca5..65691450b080 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -65,6 +65,7 @@ 
 #include <uapi/linux/netfilter/nf_tables.h>
 #include <uapi/linux/openat2.h> // struct open_how
 #include <uapi/linux/fanotify.h>
+#include <linux/mnt_idmapping.h>
 
 #include "audit.h"
 
@@ -2260,7 +2261,7 @@  static inline int audit_copy_fcaps(struct audit_names *name,
 	name->fcap.permitted = caps.permitted;
 	name->fcap.inheritable = caps.inheritable;
 	name->fcap.fE = !!(caps.magic_etc & VFS_CAP_FLAGS_EFFECTIVE);
-	name->fcap.rootid = caps.rootid;
+	name->fcap.rootid = AS_KUIDT(caps.rootid);
 	name->fcap_ver = (caps.magic_etc & VFS_CAP_REVISION_MASK) >>
 				VFS_CAP_REVISION_SHIFT;
 
@@ -2816,7 +2817,7 @@  int __audit_log_bprm_fcaps(struct linux_binprm *bprm,
 	ax->fcap.permitted = vcaps.permitted;
 	ax->fcap.inheritable = vcaps.inheritable;
 	ax->fcap.fE = !!(vcaps.magic_etc & VFS_CAP_FLAGS_EFFECTIVE);
-	ax->fcap.rootid = vcaps.rootid;
+	ax->fcap.rootid = AS_KUIDT(vcaps.rootid);
 	ax->fcap_ver = (vcaps.magic_etc & VFS_CAP_REVISION_MASK) >> VFS_CAP_REVISION_SHIFT;
 
 	ax->old_pcap.permitted   = old->cap_permitted;
diff --git a/security/commoncap.c b/security/commoncap.c
index 7cda247dc7e9..a0b5c9740759 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -711,7 +711,7 @@  int get_vfs_caps_from_disk(struct mnt_idmap *idmap,
 	cpu_caps->permitted.val &= CAP_VALID_MASK;
 	cpu_caps->inheritable.val &= CAP_VALID_MASK;
 
-	cpu_caps->rootid = vfsuid_into_kuid(rootvfsuid);
+	cpu_caps->rootid = rootvfsuid;
 
 	return 0;
 }