From 0558c1bf5a0811bf5e3753eed911a15b9bd08271 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Thu, 21 Jan 2021 14:19:23 +0100 Subject: capability: handle idmapped mounts In order to determine whether a caller holds privilege over a given inode the capability framework exposes the two helpers privileged_wrt_inode_uidgid() and capable_wrt_inode_uidgid(). The former verifies that the inode has a mapping in the caller's user namespace and the latter additionally verifies that the caller has the requested capability in their current user namespace. If the inode is accessed through an idmapped mount map it into the mount's user namespace. Afterwards the checks are identical to non-idmapped inodes. If the initial user namespace is passed all operations are a nop so non-idmapped mounts will not see a change in behavior. Link: https://lore.kernel.org/r/20210121131959.646623-5-christian.brauner@ubuntu.com Cc: Christoph Hellwig Cc: David Howells Cc: Al Viro Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig Reviewed-by: James Morris Acked-by: Serge Hallyn Signed-off-by: Christian Brauner --- include/linux/capability.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/capability.h b/include/linux/capability.h index b2f698915c0f..62bfa3ed84d7 100644 --- a/include/linux/capability.h +++ b/include/linux/capability.h @@ -247,8 +247,11 @@ static inline bool ns_capable_setid(struct user_namespace *ns, int cap) return true; } #endif /* CONFIG_MULTIUSER */ -extern bool privileged_wrt_inode_uidgid(struct user_namespace *ns, const struct inode *inode); -extern bool capable_wrt_inode_uidgid(const struct inode *inode, int cap); +bool privileged_wrt_inode_uidgid(struct user_namespace *ns, + struct user_namespace *mnt_userns, + const struct inode *inode); +bool capable_wrt_inode_uidgid(struct user_namespace *mnt_userns, + const struct inode *inode, int cap); extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap); extern bool ptracer_capable(struct task_struct *tsk, struct user_namespace *ns); static inline bool perfmon_capable(void) -- cgit