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authorSerge E. Hallyn <serue@us.ibm.com>2008-11-05 16:08:52 -0600
committerJames Morris <jmorris@namei.org>2008-11-06 07:14:51 +0800
commit1f29fae29709b4668979e244c09b2fa78ff1ad59 (patch)
treed50129066cd1f131551eb364d04542dfcf923050 /security/commoncap.c
parente21e696edb498c7f7eed42ba3096f6bbe13927b6 (diff)
downloadlinux-1f29fae29709b4668979e244c09b2fa78ff1ad59.tar.gz
file capabilities: add no_file_caps switch (v4)
Add a no_file_caps boot option when file capabilities are compiled into the kernel (CONFIG_SECURITY_FILE_CAPABILITIES=y). This allows distributions to ship a kernel with file capabilities compiled in, without forcing users to use (and understand and trust) them. When no_file_caps is specified at boot, then when a process executes a file, any file capabilities stored with that file will not be used in the calculation of the process' new capability sets. This means that booting with the no_file_caps boot option will not be the same as booting a kernel with file capabilities compiled out - in particular a task with CAP_SETPCAP will not have any chance of passing capabilities to another task (which isn't "really" possible anyway, and which may soon by killed altogether by David Howells in any case), and it will instead be able to put new capabilities in its pI. However since fI will always be empty and pI is masked with fI, it gains the task nothing. We also support the extra prctl options, setting securebits and dropping capabilities from the per-process bounding set. The other remaining difference is that killpriv, task_setscheduler, setioprio, and setnice will continue to be hooked. That will be noticable in the case where a root task changed its uid while keeping some caps, and another task owned by the new uid tries to change settings for the more privileged task. Changelog: Nov 05 2008: (v4) trivial port on top of always-start-\ with-clear-caps patch Sep 23 2008: nixed file_caps_enabled when file caps are not compiled in as it isn't used. Document no_file_caps in kernel-parameters.txt. Signed-off-by: Serge Hallyn <serue@us.ibm.com> Acked-by: Andrew G. Morgan <morgan@kernel.org> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'security/commoncap.c')
-rw-r--r--security/commoncap.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/security/commoncap.c b/security/commoncap.c
index 3976613db82..f88119cb2bc 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -281,6 +281,9 @@ static int get_file_caps(struct linux_binprm *bprm)
bprm_clear_caps(bprm);
+ if (!file_caps_enabled)
+ return 0;
+
if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)
return 0;