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fs: use low-level mapping helpers

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In a few places the vfs needs to interact with bare k{g,u}ids directly
instead of struct inode. These are just a few. In previous patches we
introduced low-level mapping helpers that are able to support
filesystems mounted an idmapping. This patch simply converts the places
to use these new helpers.

Link: https://lore.kernel.org/r/20211123114227.3124056-7-brauner@kernel.org (v1)
Link: https://lore.kernel.org/r/20211130121032.3753852-7-brauner@kernel.org (v2)
Link: https://lore.kernel.org/r/20211203111707.3901969-7-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
This commit is contained in:
Christian Brauner
2021-12-03 12:17:03 +01:00
parent 8cc5c54de4
commit 4472071331
5 changed files with 24 additions and 31 deletions
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13
security/commoncap.c
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@@ -419,7 +419,7 @@ int cap_inode_getsecurity(struct user_namespace *mnt_userns,
kroot = make_kuid(fs_ns, root);
/* If this is an idmapped mount shift the kuid. */
kroot = kuid_into_mnt(mnt_userns, kroot);
kroot = mapped_kuid_fs(mnt_userns, &init_user_ns, kroot);
/* If the root kuid maps to a valid uid in current ns, then return
* this as a nscap. */
@@ -489,6 +489,7 @@ out_free:
* @size: size of @ivalue
* @task_ns: user namespace of the caller
* @mnt_userns: user namespace of the mount the inode was found from
* @fs_userns: user namespace of the filesystem
*
* If the inode has been found through an idmapped mount the user namespace of
* the vfsmount must be passed through @mnt_userns. This function will then
@@ -498,7 +499,8 @@ out_free:
*/
static kuid_t rootid_from_xattr(const void *value, size_t size,
struct user_namespace *task_ns,
struct user_namespace *mnt_userns)
struct user_namespace *mnt_userns,
struct user_namespace *fs_userns)
{
const struct vfs_ns_cap_data *nscap = value;
kuid_t rootkid;
@@ -508,7 +510,7 @@ static kuid_t rootid_from_xattr(const void *value, size_t size,
rootid = le32_to_cpu(nscap->rootid);
rootkid = make_kuid(task_ns, rootid);
return kuid_from_mnt(mnt_userns, rootkid);
return mapped_kuid_user(mnt_userns, fs_userns, rootkid);
}
static bool validheader(size_t size, const struct vfs_cap_data *cap)
@@ -559,7 +561,8 @@ int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry,
/* user is privileged, just write the v2 */
return size;
rootid = rootid_from_xattr(*ivalue, size, task_ns, mnt_userns);
rootid = rootid_from_xattr(*ivalue, size, task_ns, mnt_userns,
&init_user_ns);
if (!uid_valid(rootid))
return -EINVAL;
@@ -700,7 +703,7 @@ int get_vfs_caps_from_disk(struct user_namespace *mnt_userns,
/* Limit the caps to the mounter of the filesystem
* or the more limited uid specified in the xattr.
*/
rootkuid = kuid_into_mnt(mnt_userns, rootkuid);
rootkuid = mapped_kuid_fs(mnt_userns, &init_user_ns, rootkuid);
if (!rootid_owns_currentns(rootkuid))
return -ENODATA;