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authorSerge Hallyn <serge@hallyn.com>2008-02-29 15:14:57 +0000
committerLinus Torvalds <torvalds@linux-foundation.org>2008-03-20 09:46:36 -0700
commitaedb60a67c10a0861af179725d060765262ba0fb (patch)
tree4a4a316f9f7d1ab0bf4da2cdd5c802bfb05c947f /security
parent457fb605834504af294916411be128a9b21fc3f6 (diff)
downloadlinux-aedb60a67c10a0861af179725d060765262ba0fb.tar.gz
linux-aedb60a67c10a0861af179725d060765262ba0fb.tar.xz
file capabilities: remove cap_task_kill()
The original justification for cap_task_kill() was as follows: check_kill_permission() does appropriate uid equivalence checks. However with file capabilities it becomes possible for an unprivileged user to execute a file with file capabilities resulting in a more privileged task with the same uid. However now that cap_task_kill() always returns 0 (permission granted) when p->uid==current->uid, the whole hook is worthless, and only likely to create more subtle problems in the corner cases where it might still be called but return -EPERM. Those cases are basically when uids are different but euid/suid is equivalent as per the check in check_kill_permission(). One example of a still-broken application is 'at' for non-root users. This patch removes cap_task_kill(). Signed-off-by: Serge Hallyn <serge@hallyn.com> Acked-by: Andrew G. Morgan <morgan@kernel.org> Earlier-version-tested-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security')
-rw-r--r--security/capability.c1
-rw-r--r--security/commoncap.c40
-rw-r--r--security/smack/smack_lsm.c5
3 files changed, 0 insertions, 46 deletions
diff --git a/security/capability.c b/security/capability.c
index 9e99f36a..2c6e06d 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -40,7 +40,6 @@ static struct security_operations capability_ops = {
.inode_need_killpriv = cap_inode_need_killpriv,
.inode_killpriv = cap_inode_killpriv,
- .task_kill = cap_task_kill,
.task_setscheduler = cap_task_setscheduler,
.task_setioprio = cap_task_setioprio,
.task_setnice = cap_task_setnice,
diff --git a/security/commoncap.c b/security/commoncap.c
index bb0c095..06d5c94 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -540,41 +540,6 @@ int cap_task_setnice (struct task_struct *p, int nice)
return cap_safe_nice(p);
}
-int cap_task_kill(struct task_struct *p, struct siginfo *info,
- int sig, u32 secid)
-{
- if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
- return 0;
-
- /*
- * Running a setuid root program raises your capabilities.
- * Killing your own setuid root processes was previously
- * allowed.
- * We must preserve legacy signal behavior in this case.
- */
- if (p->uid == current->uid)
- return 0;
-
- /* sigcont is permitted within same session */
- if (sig == SIGCONT && (task_session_nr(current) == task_session_nr(p)))
- return 0;
-
- if (secid)
- /*
- * Signal sent as a particular user.
- * Capabilities are ignored. May be wrong, but it's the
- * only thing we can do at the moment.
- * Used only by usb drivers?
- */
- return 0;
- if (cap_issubset(p->cap_permitted, current->cap_permitted))
- return 0;
- if (capable(CAP_KILL))
- return 0;
-
- return -EPERM;
-}
-
/*
* called from kernel/sys.c for prctl(PR_CABSET_DROP)
* done without task_capability_lock() because it introduces
@@ -605,11 +570,6 @@ int cap_task_setnice (struct task_struct *p, int nice)
{
return 0;
}
-int cap_task_kill(struct task_struct *p, struct siginfo *info,
- int sig, u32 secid)
-{
- return 0;
-}
#endif
void cap_task_reparent_to_init (struct task_struct *p)
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 38d7075..732ba27 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -1117,11 +1117,6 @@ static int smack_task_movememory(struct task_struct *p)
static int smack_task_kill(struct task_struct *p, struct siginfo *info,
int sig, u32 secid)
{
- int rc;
-
- rc = cap_task_kill(p, info, sig, secid);
- if (rc != 0)
- return rc;
/*
* Special cases where signals really ought to go through
* in spite of policy. Stephen Smalley suggests it may