[PATCH 2.4] CAP_FS_MASK: add CAP_LINUX_IMMUTABLE and CAP_MKNOD

Serge E. Hallyn
2009-03-25T17:40:26Z

When POSIX capabilities were introduced during the 2.1 Linux
cycle, the fs mask, which represents the capabilities which having
fsuid==0 is supposed to grant, did not include CAP_MKNOD and
CAP_LINUX_IMMUTABLE. However, before capabilities the privilege
to call these did in fact depend upon fsuid==0.

This patch introduces those capabilities into the fsmask,
restoring the old behavior.

See the thread starting at http://lkml.org/lkml/2009/3/11/157 for
reference.

Reported-by: Igor Zhbanov <izh1979@gmail.com>
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Cc: stable@kernel.org
---
include/linux/capability.h | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

diff -Nrup linux-2.4.37/include/linux/capability.h linux-2.4.37.new/include/linux/capability.h
--- linux-2.4.37/include/linux/capability.h 2008-12-02 02:01:34.000000000 -0600
+++ linux-2.4.37.new/include/linux/capability.h 2009-03-25 11:09:47.000000000 -0500
@@ -99,10 +99,6 @@ typedef __u32 kernel_cap_t;

#define CAP_FSETID 4

-/* Used to decide between falling back on the old suser() or fsuser(). */
-
-#define CAP_FS_MASK 0x1f
-
/* Overrides the restriction that the real or effective user ID of a
process sending a signal must match the real or effective user ID
of the process receiving the signal. */
@@ -301,6 +297,16 @@ extern kernel_cap_t cap_bset;

#endif

+/* Used to decide between falling back on the old suser() or fsuser(). */
+
+#define CAP_FS_MASK (CAP_TO_MASK(CAP_CHOWN) \
+ | CAP_TO_MASK(CAP_DAC_OVERRIDE) \
+ | CAP_TO_MASK(CAP_DAC_READ_SEARCH) \
+ | CAP_TO_MASK(CAP_FOWNER) \
+ | CAP_TO_MASK(CAP_FSETID) \
+ | CAP_TO_MASK(CAP_LINUX_IMMUTABLE) \
+ | CAP_TO_MASK(CAP_MKNOD))
+
#define CAP_EMPTY_SET to_cap_t(0)
#define CAP_FULL_SET to_cap_t(~0)
#define CAP_INIT_EFF_SET to_cap_t(~0 & ~CAP_TO_MASK(CAP_SETPCAP))