diff options
| author | David Howells <dhowells@redhat.com> | 2008-08-14 11:37:28 +0100 |
|---|---|---|
| committer | James Morris <jmorris@namei.org> | 2008-08-14 22:59:43 +1000 |
| commit | 5cd9c58fbe9ec92b45b27e131719af4f2bd9eb40 (patch) | |
| tree | 8573db001b4dc3c2ad97102dda42b841c40b5f6c /mm/oom_kill.c | |
| parent | 8d0968abd03ec6b407df117adc773562386702fa (diff) | |
security: Fix setting of PF_SUPERPRIV by __capable()
Fix the setting of PF_SUPERPRIV by __capable() as it could corrupt the flags
the target process if that is not the current process and it is trying to
change its own flags in a different way at the same time.
__capable() is using neither atomic ops nor locking to protect t->flags. This
patch removes __capable() and introduces has_capability() that doesn't set
PF_SUPERPRIV on the process being queried.
This patch further splits security_ptrace() in two:
(1) security_ptrace_may_access(). This passes judgement on whether one
process may access another only (PTRACE_MODE_ATTACH for ptrace() and
PTRACE_MODE_READ for /proc), and takes a pointer to the child process.
current is the parent.
(2) security_ptrace_traceme(). This passes judgement on PTRACE_TRACEME only,
and takes only a pointer to the parent process. current is the child.
In Smack and commoncap, this uses has_capability() to determine whether
the parent will be permitted to use PTRACE_ATTACH if normal checks fail.
This does not set PF_SUPERPRIV.
Two of the instances of __capable() actually only act on current, and so have
been changed to calls to capable().
Of the places that were using __capable():
(1) The OOM killer calls __capable() thrice when weighing the killability of a
process. All of these now use has_capability().
(2) cap_ptrace() and smack_ptrace() were using __capable() to check to see
whether the parent was allowed to trace any process. As mentioned above,
these have been split. For PTRACE_ATTACH and /proc, capable() is now
used, and for PTRACE_TRACEME, has_capability() is used.
(3) cap_safe_nice() only ever saw current, so now uses capable().
(4) smack_setprocattr() rejected accesses to tasks other than current just
after calling __capable(), so the order of these two tests have been
switched and capable() is used instead.
(5) In smack_file_send_sigiotask(), we need to allow privileged processes to
receive SIGIO on files they're manipulating.
(6) In smack_task_wait(), we let a process wait for a privileged process,
whether or not the process doing the waiting is privileged.
I've tested this with the LTP SELinux and syscalls testscripts.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Andrew G. Morgan <morgan@kernel.org>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'mm/oom_kill.c')
| -rw-r--r-- | mm/oom_kill.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 8a5467ee626..64e5b4bcd96 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -26,6 +26,7 @@ #include <linux/module.h> #include <linux/notifier.h> #include <linux/memcontrol.h> +#include <linux/security.h> int sysctl_panic_on_oom; int sysctl_oom_kill_allocating_task; @@ -128,7 +129,8 @@ unsigned long badness(struct task_struct *p, unsigned long uptime) * Superuser processes are usually more important, so we make it * less likely that we kill those. */ - if (__capable(p, CAP_SYS_ADMIN) || __capable(p, CAP_SYS_RESOURCE)) + if (has_capability(p, CAP_SYS_ADMIN) || + has_capability(p, CAP_SYS_RESOURCE)) points /= 4; /* @@ -137,7 +139,7 @@ unsigned long badness(struct task_struct *p, unsigned long uptime) * tend to only have this flag set on applications they think * of as important. */ - if (__capable(p, CAP_SYS_RAWIO)) + if (has_capability(p, CAP_SYS_RAWIO)) points /= 4; /* |