On Nov 29, 2023 "Seth Forshee (DigitalOcean)" <sforshee@xxxxxxxxxx> 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.
>
> Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@xxxxxxxxxx>
> ---
> include/linux/capability.h | 3 ++-
> kernel/auditsc.c | 5 +++--
> security/commoncap.c | 2 +-
> 3 files changed, 6 insertions(+), 4 deletions(-)
It might be nice if AS_KUIDT() and friends were named in such a way
as to indicate that they require a vfsuid_t parameter. At least the
call to __vfsuid_val() should flag a type mismatch if some other type
is used. Regardless, that is more of a general VFS issue and not a
problem specific to this patchset.
With the same understanding about the capabilities code and Serge ...
Acked-by: Paul Moore <paul@xxxxxxxxxxxxxx> (Audit,LSM)
> 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 cf130d81b8b4..3d045d377e5e 100644
> --- a/security/commoncap.c
> +++ b/security/commoncap.c
> @@ -710,7 +710,7 @@ 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;
> }
> --
> 2.43.0
--
paul-moore.com
