Add 64-bit capability support to the kernel

The patch supports legacy (32-bit) capability userspace, and where possible
translates 32-bit capabilities to/from userspace and the VFS to 64-bit
kernel space capabilities.  If a capability set cannot be compressed into
32-bits for consumption by user space, the system call fails, with -ERANGE.

FWIW libcap-2.00 supports this change (and earlier capability formats)

 http://www.kernel.org/pub/linux/libs/security/linux-privs/kernel-2.6/

[akpm@linux-foundation.org: coding-syle fixes]
[akpm@linux-foundation.org: use get_task_comm()]
[ezk@cs.sunysb.edu: build fix]
[akpm@linux-foundation.org: do not initialise statics to 0 or NULL]
[akpm@linux-foundation.org: unused var]
[serue@us.ibm.com: export __cap_ symbols]
Signed-off-by: Andrew G. Morgan <morgan@kernel.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: James Morris <jmorris@namei.org>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 6 deletions

diff --git a/security/dummy.c b/security/dummy.c
index c505122e22db..649326bf64ea 100644
--- a/security/dummy.c
+++ b/security/dummy.c
@@ -36,14 +36,19 @@ static int dummy_ptrace (struct task_struct *parent, struct task_struct *child)
 static int dummy_capget (struct task_struct *target, kernel_cap_t * effective,
                          kernel_cap_t * inheritable, kernel_cap_t * permitted)
 {
-        *effective = *inheritable = *permitted = 0;
         if (target->euid == 0) {
-                *permitted |= (~0 & ~CAP_FS_MASK);
-                *effective |= (~0 & ~CAP_TO_MASK(CAP_SETPCAP) & ~CAP_FS_MASK);
+                cap_set_full(*permitted);
+                cap_set_init_eff(*effective);
+        } else {
+                cap_clear(*permitted);
+                cap_clear(*effective);
         }
-        if (target->fsuid == 0) {
-                *permitted |= CAP_FS_MASK;
-                *effective |= CAP_FS_MASK;
+
+        cap_clear(*inheritable);
+
+        if (target->fsuid != 0) {
+                *permitted = cap_drop_fs_set(*permitted);
+                *effective = cap_drop_fs_set(*effective);
         }
         return 0;
 }