diff options
author | David Howells <dhowells@redhat.com> | 2008-08-14 11:37:28 +0100 |
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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) | |
download | linux-5cd9c58fbe9ec92b45b27e131719af4f2bd9eb40.tar.gz |
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 8a5467ee6265..64e5b4bcd964 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; /* |