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authorLinus Torvalds <torvalds@linux-foundation.org>2012-05-23 17:42:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-23 17:42:39 -0700
commit644473e9c60c1ff4f6351fed637a6e5551e3dce7 (patch)
tree10316518bedc735a2c6552886658d69dfd9f1eb0 /kernel/signal.c
parentfb827ec68446c83e9e8754fa9b55aed27ecc4661 (diff)
parent4b06a81f1daee668fbd6de85557bfb36dd36078f (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull user namespace enhancements from Eric Biederman: "This is a course correction for the user namespace, so that we can reach an inexpensive, maintainable, and reasonably complete implementation. Highlights: - Config guards make it impossible to enable the user namespace and code that has not been converted to be user namespace safe. - Use of the new kuid_t type ensures the if you somehow get past the config guards the kernel will encounter type errors if you enable user namespaces and attempt to compile in code whose permission checks have not been updated to be user namespace safe. - All uids from child user namespaces are mapped into the initial user namespace before they are processed. Removing the need to add an additional check to see if the user namespace of the compared uids remains the same. - With the user namespaces compiled out the performance is as good or better than it is today. - For most operations absolutely nothing changes performance or operationally with the user namespace enabled. - The worst case performance I could come up with was timing 1 billion cache cold stat operations with the user namespace code enabled. This went from 156s to 164s on my laptop (or 156ns to 164ns per stat operation). - (uid_t)-1 and (gid_t)-1 are reserved as an internal error value. Most uid/gid setting system calls treat these value specially anyway so attempting to use -1 as a uid would likely cause entertaining failures in userspace. - If setuid is called with a uid that can not be mapped setuid fails. I have looked at sendmail, login, ssh and every other program I could think of that would call setuid and they all check for and handle the case where setuid fails. - If stat or a similar system call is called from a context in which we can not map a uid we lie and return overflowuid. The LFS experience suggests not lying and returning an error code might be better, but the historical precedent with uids is different and I can not think of anything that would break by lying about a uid we can't map. - Capabilities are localized to the current user namespace making it safe to give the initial user in a user namespace all capabilities. My git tree covers all of the modifications needed to convert the core kernel and enough changes to make a system bootable to runlevel 1." Fix up trivial conflicts due to nearby independent changes in fs/stat.c * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (46 commits) userns: Silence silly gcc warning. cred: use correct cred accessor with regards to rcu read lock userns: Convert the move_pages, and migrate_pages permission checks to use uid_eq userns: Convert cgroup permission checks to use uid_eq userns: Convert tmpfs to use kuid and kgid where appropriate userns: Convert sysfs to use kgid/kuid where appropriate userns: Convert sysctl permission checks to use kuid and kgids. userns: Convert proc to use kuid/kgid where appropriate userns: Convert ext4 to user kuid/kgid where appropriate userns: Convert ext3 to use kuid/kgid where appropriate userns: Convert ext2 to use kuid/kgid where appropriate. userns: Convert devpts to use kuid/kgid where appropriate userns: Convert binary formats to use kuid/kgid where appropriate userns: Add negative depends on entries to avoid building code that is userns unsafe userns: signal remove unnecessary map_cred_ns userns: Teach inode_capable to understand inodes whose uids map to other namespaces. userns: Fail exec for suid and sgid binaries with ids outside our user namespace. userns: Convert stat to return values mapped from kuids and kgids userns: Convert user specfied uids and gids in chown into kuids and kgid userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs ...
Diffstat (limited to 'kernel/signal.c')
-rw-r--r--kernel/signal.c51
1 files changed, 20 insertions, 31 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 1a006b5d9d9..21ebe75ff85 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -767,14 +767,13 @@ static int kill_ok_by_cred(struct task_struct *t)
const struct cred *cred = current_cred();
const struct cred *tcred = __task_cred(t);
- if (cred->user->user_ns == tcred->user->user_ns &&
- (cred->euid == tcred->suid ||
- cred->euid == tcred->uid ||
- cred->uid == tcred->suid ||
- cred->uid == tcred->uid))
+ if (uid_eq(cred->euid, tcred->suid) ||
+ uid_eq(cred->euid, tcred->uid) ||
+ uid_eq(cred->uid, tcred->suid) ||
+ uid_eq(cred->uid, tcred->uid))
return 1;
- if (ns_capable(tcred->user->user_ns, CAP_KILL))
+ if (ns_capable(tcred->user_ns, CAP_KILL))
return 1;
return 0;
@@ -1020,15 +1019,6 @@ static inline int legacy_queue(struct sigpending *signals, int sig)
return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
}
-/*
- * map the uid in struct cred into user namespace *ns
- */
-static inline uid_t map_cred_ns(const struct cred *cred,
- struct user_namespace *ns)
-{
- return user_ns_map_uid(ns, cred, cred->uid);
-}
-
#ifdef CONFIG_USER_NS
static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
{
@@ -1038,8 +1028,10 @@ static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_str
if (SI_FROMKERNEL(info))
return;
- info->si_uid = user_ns_map_uid(task_cred_xxx(t, user_ns),
- current_cred(), info->si_uid);
+ rcu_read_lock();
+ info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
+ make_kuid(current_user_ns(), info->si_uid));
+ rcu_read_unlock();
}
#else
static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
@@ -1106,7 +1098,7 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
q->info.si_code = SI_USER;
q->info.si_pid = task_tgid_nr_ns(current,
task_active_pid_ns(t));
- q->info.si_uid = current_uid();
+ q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
break;
case (unsigned long) SEND_SIG_PRIV:
q->info.si_signo = sig;
@@ -1387,10 +1379,8 @@ static int kill_as_cred_perm(const struct cred *cred,
struct task_struct *target)
{
const struct cred *pcred = __task_cred(target);
- if (cred->user_ns != pcred->user_ns)
- return 0;
- if (cred->euid != pcred->suid && cred->euid != pcred->uid &&
- cred->uid != pcred->suid && cred->uid != pcred->uid)
+ if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
+ !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
return 0;
return 1;
}
@@ -1678,8 +1668,8 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
*/
rcu_read_lock();
info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
- info.si_uid = map_cred_ns(__task_cred(tsk),
- task_cred_xxx(tsk->parent, user_ns));
+ info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
+ task_uid(tsk));
rcu_read_unlock();
info.si_utime = cputime_to_clock_t(tsk->utime + tsk->signal->utime);
@@ -1762,8 +1752,7 @@ static void do_notify_parent_cldstop(struct task_struct *tsk,
*/
rcu_read_lock();
info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
- info.si_uid = map_cred_ns(__task_cred(tsk),
- task_cred_xxx(parent, user_ns));
+ info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
rcu_read_unlock();
info.si_utime = cputime_to_clock_t(tsk->utime);
@@ -1973,7 +1962,7 @@ static void ptrace_do_notify(int signr, int exit_code, int why)
info.si_signo = signr;
info.si_code = exit_code;
info.si_pid = task_pid_vnr(current);
- info.si_uid = current_uid();
+ info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
/* Let the debugger run. */
ptrace_stop(exit_code, why, 1, &info);
@@ -2181,8 +2170,8 @@ static int ptrace_signal(int signr, siginfo_t *info,
info->si_code = SI_USER;
rcu_read_lock();
info->si_pid = task_pid_vnr(current->parent);
- info->si_uid = map_cred_ns(__task_cred(current->parent),
- current_user_ns());
+ info->si_uid = from_kuid_munged(current_user_ns(),
+ task_uid(current->parent));
rcu_read_unlock();
}
@@ -2835,7 +2824,7 @@ SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
info.si_errno = 0;
info.si_code = SI_USER;
info.si_pid = task_tgid_vnr(current);
- info.si_uid = current_uid();
+ info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
return kill_something_info(sig, &info, pid);
}
@@ -2878,7 +2867,7 @@ static int do_tkill(pid_t tgid, pid_t pid, int sig)
info.si_errno = 0;
info.si_code = SI_TKILL;
info.si_pid = task_tgid_vnr(current);
- info.si_uid = current_uid();
+ info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
return do_send_specific(tgid, pid, sig, &info);
}