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authorSerge Hallyn <serge@hallyn.com>2008-02-29 15:14:57 +0000
committerChris Wright <chrisw@sous-sol.org>2008-04-18 18:53:30 -0700
commit44996dccd89ce86c7c38e37e0635d30c66279772 (patch)
tree6c07faa687a71f06d0e1454c305543f5c059bb58
parentd7d835ba45a0a2b30ed47887275e271e9ddddbdb (diff)
file capabilities: remove cap_task_kill()
upstream commit: aedb60a67c10a0861af179725d060765262ba0fb 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> [chrisw@sous-sol.org: backport to 2.6.24.4] Signed-off-by: Chris Wright <chrisw@sous-sol.org>
-rw-r--r--include/linux/security.h3
-rw-r--r--security/capability.c1
-rw-r--r--security/commoncap.c39
3 files changed, 1 insertions, 42 deletions
diff --git a/include/linux/security.h b/include/linux/security.h
index ac050830a873..d842ee36e54d 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -62,7 +62,6 @@ extern int cap_inode_need_killpriv(struct dentry *dentry);
extern int cap_inode_killpriv(struct dentry *dentry);
extern int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid, int flags);
extern void cap_task_reparent_to_init (struct task_struct *p);
-extern int cap_task_kill(struct task_struct *p, struct siginfo *info, int sig, u32 secid);
extern int cap_task_setscheduler (struct task_struct *p, int policy, struct sched_param *lp);
extern int cap_task_setioprio (struct task_struct *p, int ioprio);
extern int cap_task_setnice (struct task_struct *p, int nice);
@@ -2112,7 +2111,7 @@ static inline int security_task_kill (struct task_struct *p,
struct siginfo *info, int sig,
u32 secid)
{
- return cap_task_kill(p, info, sig, secid);
+ return 0;
}
static inline int security_task_wait (struct task_struct *p)
diff --git a/security/capability.c b/security/capability.c
index 9e99f36a8b5c..2c6e06d18fab 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 e87422e766dd..6e9065cbb7b2 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -527,40 +527,6 @@ 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;
-}
#else
int cap_task_setscheduler (struct task_struct *p, int policy,
struct sched_param *lp)
@@ -575,11 +541,6 @@ 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)