Add file_ns_capable() helper function for open-time capability checking

Nothing is using it yet, but this will allow us to delay the open-time
checks to use time, without breaking the normal UNIX permission
semantics where permissions are determined by the opener (and the file
descriptor can then be passed to a different process, or the process can
drop capabilities).

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/capability.h b/include/linux/capability.h
index 98503b79236..d9a4f7f40f3 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -35,6 +35,7 @@ struct cpu_vfs_cap_data {
 #define _KERNEL_CAP_T_SIZE     (sizeof(kernel_cap_t))
 
 
+struct file;
 struct inode;
 struct dentry;
 struct user_namespace;
@@ -211,6 +212,7 @@ extern bool capable(int cap);
 extern bool ns_capable(struct user_namespace *ns, int cap);
 extern bool nsown_capable(int cap);
 extern bool inode_capable(const struct inode *inode, int cap);
+extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
 
 /* audit system wants to get cap info from files as well */
 extern int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps);