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    SubjectRe: [PATCH 1/1] security: introduce fs caps
    On Wed, Nov 15, 2006 at 09:08:55PM +0900, KaiGai Kohei wrote:
    | Serge E. Hallyn wrote:
    | >Quoting Bill O'Donnell (billodo@sgi.com):
    | >>8102 execve("/sbin/setfcaps", ["setfcaps", "cap_net_raw=ep",
    | >>"/bin/ping"], [/* 67 vars */]) = 0
    | - snip -
    | >>8102 capget(0x19980330, 0, {0, 0, 0}) = -1 EINVAL (Invalid argument)
    | >
    | >I don't see why this capget is returning -EINVAL. In fact I don't see
    | >why it happens at all - cap_inode_setxattr would check
    | >capable(CAP_SYS_ADMIN), but setxattr hasn't been called yet. Looking at
    | >both libcap and setfcaps.c, I don't see where the capget comes from.
    | >
    | >As for the -EINVAL, kernel/capability.c:sys_capget() returns -EINVAL if
    | >the _LINUX_CAPABILITY_VERSION is wrong - you have 0x19980330 which is
    | >correct - if pid < 0 - but you send in 0 - or if security_capget
    | >returns -EINVAL, which cap_capget (and dummy_capget) don't do.
    | >
    | >Kaigai, do you have any ideas?
    |
    | Bill said that he uses SLES10/ia64, so the version of libcap is different
    | from Fedora Core's one. 'libcap-1.92-499.4.src.rpm' is bandled.
    |
    | Then, I found a strange code in libcap-1.92-499.4.src.rpm.
    |
    | The setfcaps calls cap_from_text() which is defined in libcap to parse
    | the command line argument. It has the following function call chains:
    |
    | cap_from_text()
    | -> cap_init()
    | -> _libcap_establish_api()

    - snip -

    | capget() is called from _libcap_establish_api() with full-zeroed
    | __user_cap_header_struct object at first time.
    | The result of this, sys_capget() in kernel will return -EINVAL.
    | (Why did strace say the first argument is 0x19980330?)
    |
    | Probably, Bill didn't update libcap.so.
    No, I didn't...
    certify:~/libcap-1.10/progs # ls -altr /lib/libcap*
    -rwxr-xr-x 1 root root 22672 2006-06-16 09:56 /lib/libcap.so.1.92
    -rw-r--r-- 1 root root 53363 2006-11-13 16:04 /lib/libcap.so.1.10
    lrwxrwxrwx 1 root root 14 2006-11-13 16:04 /lib/libcap.so.1 ->libcap.so.1.92
    lrwxrwxrwx 1 root root 11 2006-11-13 16:04 /lib/libcap.so -> libcap.so.1

    |
    | But I can't recommend Bill to update libcap immediately.
    | As Hawk Xu said, it may cause a serious problem on the distro
    | except Fedora Core 6. :(

    What version of libcap is on FC6?

    |
    | I have to recommend to use 'fscaps-1.0-kg.i386.rpm' now.
    | It includes the implementation of interaction between application and xattr.
    | (Of couse, it's one of the features which should be provided by libcap.)

    But that won't work on ia64 will it?

    Thanks,
    Bill


    --
    Bill O'Donnell
    SGI
    651.683.3079
    billodo@sgi.com
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