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.
However, 2.2 does not have CAP_MKNOD, instead using CAP_SYS_ADMIN to authorize sys_mknod. We don't want to put CAP_SYS_ADMIN in CAP_FS_MASK because it carries too many non-fs implications. This patch introduces CAP_LINUX_IMMUTABLE into the fsmask. See the thread starting at http://lkml.org/lkml/2009/3/11/157 for reference. Reported-by: Igor Zhbanov <[email protected]> Signed-off-by: Serge E. Hallyn <[email protected]> Cc: [email protected] --- include/linux/capability.h | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff -Nrup linux-2.2.26/include/linux/capability.h linux-2.2.26.new/include/linux/capability.h --- linux-2.2.26/include/linux/capability.h 2004-02-23 07:44:47.000000000 -0600 +++ linux-2.2.26.new/include/linux/capability.h 2009-03-25 11:12:08.000000000 -0500 @@ -98,10 +98,6 @@ 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. */ @@ -288,6 +284,15 @@ 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)) + #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)) -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
