* [PATCH 01/08] Add a user_namespace as creator/owner of uts_namespace
2011-01-11 6:43 userns: targeted capabilities v4 Serge E. Hallyn
@ 2011-01-11 6:43 ` Serge E. Hallyn
2011-01-11 6:44 ` [PATCH 02/08] security: Make capabilities relative to the user namespace Serge E. Hallyn
` (6 subsequent siblings)
7 siblings, 0 replies; 14+ messages in thread
From: Serge E. Hallyn @ 2011-01-11 6:43 UTC (permalink / raw)
To: Serge E. Hallyn
Cc: LSM, James Morris, Kees Cook, containers, kernel list,
Eric W. Biederman, Alexey Dobriyan, Michael Kerrisk,
Bastian Blank
copy_process() handles CLONE_NEWUSER before the rest of the
namespaces. So in the case of clone(CLONE_NEWUSER|CLONE_NEWUTS)
the new uts namespace will have the new user namespace as its
owner. That is what we want, since we want root in that new
userns to be able to have privilege over it.
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
---
include/linux/utsname.h | 3 +++
init/version.c | 2 ++
kernel/nsproxy.c | 3 +++
kernel/user.c | 8 ++++++--
kernel/utsname.c | 4 ++++
5 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/include/linux/utsname.h b/include/linux/utsname.h
index 69f3997..85171be 100644
--- a/include/linux/utsname.h
+++ b/include/linux/utsname.h
@@ -37,9 +37,12 @@ struct new_utsname {
#include <linux/nsproxy.h>
#include <linux/err.h>
+struct user_namespace;
+
struct uts_namespace {
struct kref kref;
struct new_utsname name;
+ struct user_namespace *user_ns;
};
extern struct uts_namespace init_uts_ns;
diff --git a/init/version.c b/init/version.c
index 79fb8c2..9eb19fb 100644
--- a/init/version.c
+++ b/init/version.c
@@ -21,6 +21,7 @@ extern int version_string(LINUX_VERSION_CODE);
int version_string(LINUX_VERSION_CODE);
#endif
+extern struct user_namespace init_user_ns;
struct uts_namespace init_uts_ns = {
.kref = {
.refcount = ATOMIC_INIT(2),
@@ -33,6 +34,7 @@ struct uts_namespace init_uts_ns = {
.machine = UTS_MACHINE,
.domainname = UTS_DOMAINNAME,
},
+ .user_ns = &init_user_ns,
};
EXPORT_SYMBOL_GPL(init_uts_ns);
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index f74e6c0..5a22dcf 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -74,6 +74,9 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
err = PTR_ERR(new_nsp->uts_ns);
goto out_uts;
}
+ put_user_ns(new_nsp->uts_ns->user_ns);
+ new_nsp->uts_ns->user_ns = task_cred_xxx(tsk, user)->user_ns;
+ get_user_ns(new_nsp->uts_ns->user_ns);
new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
if (IS_ERR(new_nsp->ipc_ns)) {
diff --git a/kernel/user.c b/kernel/user.c
index 5c598ca..9e03e9c 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -17,9 +17,13 @@
#include <linux/module.h>
#include <linux/user_namespace.h>
+/*
+ * userns count is 1 for root user, 1 for init_uts_ns,
+ * and 1 for... ?
+ */
struct user_namespace init_user_ns = {
.kref = {
- .refcount = ATOMIC_INIT(2),
+ .refcount = ATOMIC_INIT(3),
},
.creator = &root_user,
};
@@ -47,7 +51,7 @@ static struct kmem_cache *uid_cachep;
*/
static DEFINE_SPINLOCK(uidhash_lock);
-/* root_user.__count is 2, 1 for init task cred, 1 for init_user_ns->creator */
+/* root_user.__count is 2, 1 for init task cred, 1 for init_user_ns->user_ns */
struct user_struct root_user = {
.__count = ATOMIC_INIT(2),
.processes = ATOMIC_INIT(1),
diff --git a/kernel/utsname.c b/kernel/utsname.c
index 8a82b4b..a7b3a8d 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -14,6 +14,7 @@
#include <linux/utsname.h>
#include <linux/err.h>
#include <linux/slab.h>
+#include <linux/user_namespace.h>
static struct uts_namespace *create_uts_ns(void)
{
@@ -40,6 +41,8 @@ static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
down_read(&uts_sem);
memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
+ ns->user_ns = old_ns->user_ns;
+ get_user_ns(ns->user_ns);
up_read(&uts_sem);
return ns;
}
@@ -71,5 +74,6 @@ void free_uts_ns(struct kref *kref)
struct uts_namespace *ns;
ns = container_of(kref, struct uts_namespace, kref);
+ put_user_ns(ns->user_ns);
kfree(ns);
}
--
1.7.0.4
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH 02/08] security: Make capabilities relative to the user namespace.
2011-01-11 6:43 userns: targeted capabilities v4 Serge E. Hallyn
2011-01-11 6:43 ` [PATCH 01/08] Add a user_namespace as creator/owner of uts_namespace Serge E. Hallyn
@ 2011-01-11 6:44 ` Serge E. Hallyn
2011-01-11 6:44 ` [PATCH 03/08] allow sethostname in a container Serge E. Hallyn
` (5 subsequent siblings)
7 siblings, 0 replies; 14+ messages in thread
From: Serge E. Hallyn @ 2011-01-11 6:44 UTC (permalink / raw)
To: Serge E. Hallyn
Cc: LSM, James Morris, Kees Cook, containers, kernel list,
Eric W. Biederman, Alexey Dobriyan, Michael Kerrisk,
Bastian Blank
- Introduce ns_capable to test for a capability in a non-default
user namespace.
- Teach cap_capable to handle capabilities in a non-default
user namespace.
The motivation is to get to the unprivileged creation of new
namespaces. It looks like this gets us 90% of the way there, with
only potential uid confusion issues left.
I still need to handle getting all caps after creation but otherwise I
think I have a good starter patch that achieves all of your goals.
Changelog:
11/05/2010: [serge] add apparmor
12/14/2010: [serge] fix capabilities to created user namespaces
Without this, if user serge creates a user_ns, he won't have
capabilities to the user_ns he created. THis is because we
were first checking whether his effective caps had the caps
he needed and returning -EPERM if not, and THEN checking whether
he was the creator. Reverse those checks.
12/16/2010: [serge] security_real_capable needs ns argument in !security case
01/11/2011: [serge] add task_ns_capable helper
01/11/2011: [serge] add nsown_capable() helper per Bastian Blank suggestion
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
fold into 2
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
---
include/linux/capability.h | 10 ++++++++--
include/linux/security.h | 22 ++++++++++++----------
kernel/capability.c | 32 ++++++++++++++++++++++++++++++--
security/apparmor/lsm.c | 5 +++--
security/commoncap.c | 40 +++++++++++++++++++++++++++++++++-------
security/security.c | 12 ++++++------
security/selinux/hooks.c | 14 +++++++++-----
7 files changed, 101 insertions(+), 34 deletions(-)
diff --git a/include/linux/capability.h b/include/linux/capability.h
index 90012b9..1711ff5 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -541,7 +541,7 @@ extern const kernel_cap_t __cap_init_eff_set;
*
* Note that this does not set PF_SUPERPRIV on the task.
*/
-#define has_capability(t, cap) (security_real_capable((t), (cap)) == 0)
+#define has_capability(t, cap) (security_real_capable((t), &init_user_ns, (cap)) == 0)
/**
* has_capability_noaudit - Determine if a task has a superior capability available (unaudited)
@@ -555,9 +555,15 @@ extern const kernel_cap_t __cap_init_eff_set;
* Note that this does not set PF_SUPERPRIV on the task.
*/
#define has_capability_noaudit(t, cap) \
- (security_real_capable_noaudit((t), (cap)) == 0)
+ (security_real_capable_noaudit((t), &init_user_ns, (cap)) == 0)
+struct user_namespace;
+extern struct user_namespace init_user_ns;
extern int capable(int cap);
+extern int ns_capable(struct user_namespace *ns, int cap);
+extern int task_ns_capable(struct task_struct *t, int cap);
+
+#define nsown_capable(cap) (ns_capable(current_user_ns(), (cap)))
/* audit system wants to get cap info from files as well */
struct dentry;
diff --git a/include/linux/security.h b/include/linux/security.h
index 39f5b7e..2141f5a 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -46,13 +46,14 @@
struct ctl_table;
struct audit_krule;
+struct user_namespace;
/*
* These functions are in security/capability.c and are used
* as the default capabilities functions
*/
extern int cap_capable(struct task_struct *tsk, const struct cred *cred,
- int cap, int audit);
+ struct user_namespace *ns, int cap, int audit);
extern int cap_settime(struct timespec *ts, struct timezone *tz);
extern int cap_ptrace_access_check(struct task_struct *child, unsigned int mode);
extern int cap_ptrace_traceme(struct task_struct *parent);
@@ -1258,6 +1259,7 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
* credentials.
* @tsk contains the task_struct for the process.
* @cred contains the credentials to use.
+ * @ns contains the user namespace we want the capability in
* @cap contains the capability <include/linux/capability.h>.
* @audit: Whether to write an audit message or not
* Return 0 if the capability is granted for @tsk.
@@ -1386,7 +1388,7 @@ struct security_operations {
const kernel_cap_t *inheritable,
const kernel_cap_t *permitted);
int (*capable) (struct task_struct *tsk, const struct cred *cred,
- int cap, int audit);
+ struct user_namespace *ns, int cap, int audit);
int (*sysctl) (struct ctl_table *table, int op);
int (*quotactl) (int cmds, int type, int id, struct super_block *sb);
int (*quota_on) (struct dentry *dentry);
@@ -1668,9 +1670,9 @@ int security_capset(struct cred *new, const struct cred *old,
const kernel_cap_t *effective,
const kernel_cap_t *inheritable,
const kernel_cap_t *permitted);
-int security_capable(int cap);
-int security_real_capable(struct task_struct *tsk, int cap);
-int security_real_capable_noaudit(struct task_struct *tsk, int cap);
+int security_capable(struct user_namespace *ns, int cap);
+int security_real_capable(struct task_struct *tsk, struct user_namespace *ns, int cap);
+int security_real_capable_noaudit(struct task_struct *tsk, struct user_namespace *ns, int cap);
int security_sysctl(struct ctl_table *table, int op);
int security_quotactl(int cmds, int type, int id, struct super_block *sb);
int security_quota_on(struct dentry *dentry);
@@ -1864,26 +1866,26 @@ static inline int security_capset(struct cred *new,
static inline int security_capable(int cap)
{
- return cap_capable(current, current_cred(), cap, SECURITY_CAP_AUDIT);
+ return cap_capable(current, current_cred(), &init_user_ns, cap, SECURITY_CAP_AUDIT);
}
-static inline int security_real_capable(struct task_struct *tsk, int cap)
+static inline int security_real_capable(struct task_struct *tsk, struct user_namespace *ns, int cap)
{
int ret;
rcu_read_lock();
- ret = cap_capable(tsk, __task_cred(tsk), cap, SECURITY_CAP_AUDIT);
+ ret = cap_capable(tsk, __task_cred(tsk), ns, cap, SECURITY_CAP_AUDIT);
rcu_read_unlock();
return ret;
}
static inline
-int security_real_capable_noaudit(struct task_struct *tsk, int cap)
+int security_real_capable_noaudit(struct task_struct *tsk, struct user_namespace *ns, int cap)
{
int ret;
rcu_read_lock();
- ret = cap_capable(tsk, __task_cred(tsk), cap,
+ ret = cap_capable(tsk, __task_cred(tsk), ns, cap,
SECURITY_CAP_NOAUDIT);
rcu_read_unlock();
return ret;
diff --git a/kernel/capability.c b/kernel/capability.c
index 2f05303..f7a8dd3 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -14,6 +14,7 @@
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/pid_namespace.h>
+#include <linux/user_namespace.h>
#include <asm/uaccess.h>
/*
@@ -301,15 +302,42 @@ error:
*/
int capable(int cap)
{
+ return ns_capable(&init_user_ns, cap);
+}
+EXPORT_SYMBOL(capable);
+
+/**
+ * ns_capable - Determine if the current task has a superior capability in effect
+ * @ns: The usernamespace we want the capability in
+ * @cap: The capability to be tested for
+ *
+ * Return true if the current task has the given superior capability currently
+ * available for use, false if not.
+ *
+ * This sets PF_SUPERPRIV on the task if the capability is available on the
+ * assumption that it's about to be used.
+ */
+int ns_capable(struct user_namespace *ns, int cap)
+{
if (unlikely(!cap_valid(cap))) {
printk(KERN_CRIT "capable() called with invalid cap=%u\n", cap);
BUG();
}
- if (security_capable(cap) == 0) {
+ if (security_capable(ns, cap) == 0) {
current->flags |= PF_SUPERPRIV;
return 1;
}
return 0;
}
-EXPORT_SYMBOL(capable);
+EXPORT_SYMBOL(ns_capable);
+
+/*
+ * does current have capability 'cap' to the user namespace of task
+ * 't'. Return true if it does, false otherwise.
+ */
+int task_ns_capable(struct task_struct *t, int cap)
+{
+ return ns_capable(task_cred_xxx(t, user)->user_ns, cap);
+}
+EXPORT_SYMBOL(task_ns_capable);
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index fa778a7..00d227f 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -22,6 +22,7 @@
#include <linux/ctype.h>
#include <linux/sysctl.h>
#include <linux/audit.h>
+#include <linux/user_namespace.h>
#include <net/sock.h>
#include "include/apparmor.h"
@@ -137,11 +138,11 @@ static int apparmor_capget(struct task_struct *target, kernel_cap_t *effective,
}
static int apparmor_capable(struct task_struct *task, const struct cred *cred,
- int cap, int audit)
+ struct user_namespace *ns, int cap, int audit)
{
struct aa_profile *profile;
/* cap_capable returns 0 on success, else -EPERM */
- int error = cap_capable(task, cred, cap, audit);
+ int error = cap_capable(task, cred, ns, cap, audit);
if (!error) {
profile = aa_cred_profile(cred);
if (!unconfined(profile))
diff --git a/security/commoncap.c b/security/commoncap.c
index e58b5d8..9d910e6 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -27,6 +27,7 @@
#include <linux/sched.h>
#include <linux/prctl.h>
#include <linux/securebits.h>
+#include <linux/user_namespace.h>
/*
* If a non-root user executes a setuid-root binary in
@@ -68,6 +69,7 @@ EXPORT_SYMBOL(cap_netlink_recv);
* cap_capable - Determine whether a task has a particular effective capability
* @tsk: The task to query
* @cred: The credentials to use
+ * @ns: The user namespace in which we need the capability
* @cap: The capability to check for
* @audit: Whether to write an audit message or not
*
@@ -79,10 +81,32 @@ EXPORT_SYMBOL(cap_netlink_recv);
* cap_has_capability() returns 0 when a task has a capability, but the
* kernel's capable() and has_capability() returns 1 for this case.
*/
-int cap_capable(struct task_struct *tsk, const struct cred *cred, int cap,
- int audit)
+int cap_capable(struct task_struct *tsk, const struct cred *cred,
+ struct user_namespace *targ_ns, int cap, int audit)
{
- return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
+ for (;;) {
+ /* The creator of the user namespace has all caps. */
+ if (targ_ns->creator == cred->user)
+ return 0;
+
+ /* Do we have the necessary capabilities? */
+ if (targ_ns == cred->user->user_ns)
+ return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
+
+ /* Have we tried all of the parent namespaces? */
+ if (targ_ns == &init_user_ns)
+ return -EPERM;
+
+ /* If you have the capability in a parent user ns you have it
+ * in the over all children user namespaces as well, so see
+ * if this process has the capability in the parent user
+ * namespace.
+ */
+ targ_ns = targ_ns->creator->user_ns;
+ }
+
+ /* We never get here */
+ return -EPERM;
}
/**
@@ -177,7 +201,8 @@ static inline int cap_inh_is_capped(void)
/* they are so limited unless the current task has the CAP_SETPCAP
* capability
*/
- if (cap_capable(current, current_cred(), CAP_SETPCAP,
+ if (cap_capable(current, current_cred(),
+ current_cred()->user->user_ns, CAP_SETPCAP,
SECURITY_CAP_AUDIT) == 0)
return 0;
return 1;
@@ -829,7 +854,8 @@ int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
& (new->securebits ^ arg2)) /*[1]*/
|| ((new->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/
|| (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
- || (cap_capable(current, current_cred(), CAP_SETPCAP,
+ || (cap_capable(current, current_cred(),
+ current_cred()->user->user_ns, CAP_SETPCAP,
SECURITY_CAP_AUDIT) != 0) /*[4]*/
/*
* [1] no changing of bits that are locked
@@ -894,7 +920,7 @@ int cap_vm_enough_memory(struct mm_struct *mm, long pages)
{
int cap_sys_admin = 0;
- if (cap_capable(current, current_cred(), CAP_SYS_ADMIN,
+ if (cap_capable(current, current_cred(), &init_user_ns, CAP_SYS_ADMIN,
SECURITY_CAP_NOAUDIT) == 0)
cap_sys_admin = 1;
return __vm_enough_memory(mm, pages, cap_sys_admin);
@@ -921,7 +947,7 @@ int cap_file_mmap(struct file *file, unsigned long reqprot,
int ret = 0;
if (addr < dac_mmap_min_addr) {
- ret = cap_capable(current, current_cred(), CAP_SYS_RAWIO,
+ ret = cap_capable(current, current_cred(), &init_user_ns, CAP_SYS_RAWIO,
SECURITY_CAP_AUDIT);
/* set PF_SUPERPRIV if it turns out we allow the low mmap */
if (ret == 0)
diff --git a/security/security.c b/security/security.c
index a774256..a7c1a1f 100644
--- a/security/security.c
+++ b/security/security.c
@@ -172,30 +172,30 @@ int security_capset(struct cred *new, const struct cred *old,
effective, inheritable, permitted);
}
-int security_capable(int cap)
+int security_capable(struct user_namespace *ns, int cap)
{
- return security_ops->capable(current, current_cred(), cap,
+ return security_ops->capable(current, current_cred(), ns, cap,
SECURITY_CAP_AUDIT);
}
-int security_real_capable(struct task_struct *tsk, int cap)
+int security_real_capable(struct task_struct *tsk, struct user_namespace *ns, int cap)
{
const struct cred *cred;
int ret;
cred = get_task_cred(tsk);
- ret = security_ops->capable(tsk, cred, cap, SECURITY_CAP_AUDIT);
+ ret = security_ops->capable(tsk, cred, ns, cap, SECURITY_CAP_AUDIT);
put_cred(cred);
return ret;
}
-int security_real_capable_noaudit(struct task_struct *tsk, int cap)
+int security_real_capable_noaudit(struct task_struct *tsk, struct user_namespace *ns, int cap)
{
const struct cred *cred;
int ret;
cred = get_task_cred(tsk);
- ret = security_ops->capable(tsk, cred, cap, SECURITY_CAP_NOAUDIT);
+ ret = security_ops->capable(tsk, cred, ns, cap, SECURITY_CAP_NOAUDIT);
put_cred(cred);
return ret;
}
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 65fa8bf..b9a6a53 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -77,6 +77,7 @@
#include <linux/mutex.h>
#include <linux/posix-timers.h>
#include <linux/syslog.h>
+#include <linux/user_namespace.h>
#include "avc.h"
#include "objsec.h"
@@ -1423,6 +1424,7 @@ static int current_has_perm(const struct task_struct *tsk,
/* Check whether a task is allowed to use a capability. */
static int task_has_capability(struct task_struct *tsk,
const struct cred *cred,
+ struct user_namespace *ns,
int cap, int audit)
{
struct common_audit_data ad;
@@ -1851,15 +1853,15 @@ static int selinux_capset(struct cred *new, const struct cred *old,
*/
static int selinux_capable(struct task_struct *tsk, const struct cred *cred,
- int cap, int audit)
+ struct user_namespace *ns, int cap, int audit)
{
int rc;
- rc = cap_capable(tsk, cred, cap, audit);
+ rc = cap_capable(tsk, cred, ns, cap, audit);
if (rc)
return rc;
- return task_has_capability(tsk, cred, cap, audit);
+ return task_has_capability(tsk, cred, ns, cap, audit);
}
static int selinux_sysctl_get_sid(ctl_table *table, u16 tclass, u32 *sid)
@@ -2012,7 +2014,8 @@ static int selinux_vm_enough_memory(struct mm_struct *mm, long pages)
{
int rc, cap_sys_admin = 0;
- rc = selinux_capable(current, current_cred(), CAP_SYS_ADMIN,
+ rc = selinux_capable(current, current_cred(),
+ &init_user_ns, CAP_SYS_ADMIN,
SECURITY_CAP_NOAUDIT);
if (rc == 0)
cap_sys_admin = 1;
@@ -2826,7 +2829,8 @@ static int selinux_inode_getsecurity(const struct inode *inode, const char *name
* and lack of permission just means that we fall back to the
* in-core context value, not a denial.
*/
- error = selinux_capable(current, current_cred(), CAP_MAC_ADMIN,
+ error = selinux_capable(current, current_cred(),
+ &init_user_ns, CAP_MAC_ADMIN,
SECURITY_CAP_NOAUDIT);
if (!error)
error = security_sid_to_context_force(isec->sid, &context,
--
1.7.0.4
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH 03/08] allow sethostname in a container
2011-01-11 6:43 userns: targeted capabilities v4 Serge E. Hallyn
2011-01-11 6:43 ` [PATCH 01/08] Add a user_namespace as creator/owner of uts_namespace Serge E. Hallyn
2011-01-11 6:44 ` [PATCH 02/08] security: Make capabilities relative to the user namespace Serge E. Hallyn
@ 2011-01-11 6:44 ` Serge E. Hallyn
2011-01-11 16:14 ` Serge E. Hallyn
2011-01-11 6:44 ` [PATCH 04/08] allow killing tasks in your own or child userns Serge E. Hallyn
` (4 subsequent siblings)
7 siblings, 1 reply; 14+ messages in thread
From: Serge E. Hallyn @ 2011-01-11 6:44 UTC (permalink / raw)
To: Serge E. Hallyn
Cc: LSM, James Morris, Kees Cook, containers, kernel list,
Eric W. Biederman, Alexey Dobriyan, Michael Kerrisk,
Bastian Blank
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
---
kernel/sys.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/sys.c b/kernel/sys.c
index 2745dcd..9b9b03b 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1171,7 +1171,7 @@ SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
int errno;
char tmp[__NEW_UTS_LEN];
- if (!capable(CAP_SYS_ADMIN))
+ if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
return -EPERM;
if (len < 0 || len > __NEW_UTS_LEN)
return -EINVAL;
--
1.7.0.4
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [PATCH 03/08] allow sethostname in a container
2011-01-11 6:44 ` [PATCH 03/08] allow sethostname in a container Serge E. Hallyn
@ 2011-01-11 16:14 ` Serge E. Hallyn
2011-02-04 15:56 ` Serge E. Hallyn
0 siblings, 1 reply; 14+ messages in thread
From: Serge E. Hallyn @ 2011-01-11 16:14 UTC (permalink / raw)
To: Serge E. Hallyn
Cc: LSM, James Morris, Kees Cook, containers, kernel list,
Eric W. Biederman, Alexey Dobriyan, Michael Kerrisk,
Bastian Blank
Quoting Serge E. Hallyn (serge@hallyn.com):
> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
> ---
> kernel/sys.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/sys.c b/kernel/sys.c
> index 2745dcd..9b9b03b 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -1171,7 +1171,7 @@ SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
> int errno;
> char tmp[__NEW_UTS_LEN];
>
> - if (!capable(CAP_SYS_ADMIN))
> + if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
> return -EPERM;
> if (len < 0 || len > __NEW_UTS_LEN)
> return -EINVAL;
> --
> 1.7.0.4
An interesting note here is that since the task doing ns_exec (and
therefore in the init_user_ns) requires CAP_SYS_ADMIN to unshare,
this check will actually always be true if uts_ns was not unshared.
If uts is unshared, then regular capabilities semantics in the
child user_ns apply (that is, root can do sethostname, unpriv user
cannot) The intent is that user namespaces will eventually allow
unprivileged users to unshare, after which this will make much more
sense.
-serge
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH 03/08] allow sethostname in a container
2011-01-11 16:14 ` Serge E. Hallyn
@ 2011-02-04 15:56 ` Serge E. Hallyn
0 siblings, 0 replies; 14+ messages in thread
From: Serge E. Hallyn @ 2011-02-04 15:56 UTC (permalink / raw)
To: Serge E. Hallyn
Cc: LSM, James Morris, Kees Cook, containers, kernel list,
Eric W. Biederman, Alexey Dobriyan, Michael Kerrisk,
Bastian Blank
Quoting Serge E. Hallyn (serge@hallyn.com):
> Quoting Serge E. Hallyn (serge@hallyn.com):
> > Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
> > ---
> > kernel/sys.c | 2 +-
> > 1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/kernel/sys.c b/kernel/sys.c
> > index 2745dcd..9b9b03b 100644
> > --- a/kernel/sys.c
> > +++ b/kernel/sys.c
> > @@ -1171,7 +1171,7 @@ SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
> > int errno;
> > char tmp[__NEW_UTS_LEN];
> >
> > - if (!capable(CAP_SYS_ADMIN))
> > + if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
> > return -EPERM;
> > if (len < 0 || len > __NEW_UTS_LEN)
> > return -EINVAL;
> > --
> > 1.7.0.4
>
> An interesting note here is that since the task doing ns_exec (and
> therefore in the init_user_ns) requires CAP_SYS_ADMIN to unshare,
> this check will actually always be true if uts_ns was not unshared.
Noone ever called me on this, so for the sake of posterity reading the
m-l archives: what I said above is not true. If uts_ns was not
unshared, then current->nsproxy->uts_ns->user_ns != current_user_ns(),
so current should not have ns_capable(current->nsproxy->uts_ns->user_ns,
CAP_SYS_ADMIN). So the check will always return false.
> If uts is unshared, then regular capabilities semantics in the
> child user_ns apply (that is, root can do sethostname, unpriv user
> cannot) The intent is that user namespaces will eventually allow
> unprivileged users to unshare, after which this will make much more
> sense.
>
> -serge
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH 04/08] allow killing tasks in your own or child userns
2011-01-11 6:43 userns: targeted capabilities v4 Serge E. Hallyn
` (2 preceding siblings ...)
2011-01-11 6:44 ` [PATCH 03/08] allow sethostname in a container Serge E. Hallyn
@ 2011-01-11 6:44 ` Serge E. Hallyn
2011-01-11 6:44 ` [PATCH 05/08] Allow ptrace from non-init user namespaces Serge E. Hallyn
` (3 subsequent siblings)
7 siblings, 0 replies; 14+ messages in thread
From: Serge E. Hallyn @ 2011-01-11 6:44 UTC (permalink / raw)
To: Serge E. Hallyn
Cc: LSM, James Morris, Kees Cook, containers, kernel list,
Eric W. Biederman, Alexey Dobriyan, Michael Kerrisk,
Bastian Blank
Changelog:
Dec 8: Fixed bug in my check_kill_permission pointed out by
Eric Biederman.
Dec 13: Apply Eric's suggestion to pass target task into kill_ok_by_cred()
for clarity
Dec 31: address comment by Eric Biederman:
don't need cred/tcred in check_kill_permission.
Jan 1: use const cred struct.
Jan 11: Per Bastian Blank's advice, clean up kill_ok_by_cred().
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
kernel/signal.c | 30 ++++++++++++++++++++++--------
1 files changed, 22 insertions(+), 8 deletions(-)
diff --git a/kernel/signal.c b/kernel/signal.c
index 4e3cff1..b64d06e 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -636,13 +636,33 @@ static inline bool si_fromuser(const struct siginfo *info)
}
/*
+ * called with RCU read lock from check_kill_permission()
+ */
+static inline 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)
+ return 1;
+
+ if (ns_capable(tcred->user->user_ns, CAP_KILL))
+ return 1;
+
+ return 0;
+}
+
+/*
* Bad permissions for sending the signal
* - the caller must hold the RCU read lock
*/
static int check_kill_permission(int sig, struct siginfo *info,
struct task_struct *t)
{
- const struct cred *cred, *tcred;
struct pid *sid;
int error;
@@ -656,14 +676,8 @@ static int check_kill_permission(int sig, struct siginfo *info,
if (error)
return error;
- cred = current_cred();
- tcred = __task_cred(t);
if (!same_thread_group(current, t) &&
- (cred->euid ^ tcred->suid) &&
- (cred->euid ^ tcred->uid) &&
- (cred->uid ^ tcred->suid) &&
- (cred->uid ^ tcred->uid) &&
- !capable(CAP_KILL)) {
+ !kill_ok_by_cred(t)) {
switch (sig) {
case SIGCONT:
sid = task_session(t);
--
1.7.0.4
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH 05/08] Allow ptrace from non-init user namespaces
2011-01-11 6:43 userns: targeted capabilities v4 Serge E. Hallyn
` (3 preceding siblings ...)
2011-01-11 6:44 ` [PATCH 04/08] allow killing tasks in your own or child userns Serge E. Hallyn
@ 2011-01-11 6:44 ` Serge E. Hallyn
2011-01-14 14:46 ` Bastian Blank
2011-01-11 6:44 ` [PATCH 06/08] user namespaces: convert all capable checks in kernel/sys.c Serge E. Hallyn
` (2 subsequent siblings)
7 siblings, 1 reply; 14+ messages in thread
From: Serge E. Hallyn @ 2011-01-11 6:44 UTC (permalink / raw)
To: Serge E. Hallyn
Cc: LSM, James Morris, Kees Cook, containers, kernel list,
Eric W. Biederman, Alexey Dobriyan, Michael Kerrisk,
Bastian Blank
ptrace is allowed to tasks in the same user namespace according to
the usual rules (i.e. the same rules as for two tasks in the init
user namespace). ptrace is also allowed to a user namespace to
which the current task the has CAP_SYS_PTRACE capability.
Changelog:
Dec 31: Address feedback by Eric:
. Correct ptrace uid check
. Rename may_ptrace_ns to ptrace_capable
. Also fix the cap_ptrace checks.
Jan 1: Use const cred struct
Jan 11: use task_ns_capable() in place of ptrace_capable().
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
---
include/linux/capability.h | 2 +
include/linux/user_namespace.h | 9 +++++++
kernel/ptrace.c | 27 ++++++++++++----------
kernel/user_namespace.c | 16 +++++++++++++
security/commoncap.c | 48 +++++++++++++++++++++++++++++++++------
5 files changed, 82 insertions(+), 20 deletions(-)
diff --git a/include/linux/capability.h b/include/linux/capability.h
index 1711ff5..9095fdc 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -543,6 +543,8 @@ extern const kernel_cap_t __cap_init_eff_set;
*/
#define has_capability(t, cap) (security_real_capable((t), &init_user_ns, (cap)) == 0)
+#define has_ns_capability(t, ns, cap) (security_real_capable((t), (ns), (cap)) == 0)
+
/**
* has_capability_noaudit - Determine if a task has a superior capability available (unaudited)
* @t: The task in question
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 8178156..91c4f10 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -39,6 +39,9 @@ static inline void put_user_ns(struct user_namespace *ns)
uid_t user_ns_map_uid(struct user_namespace *to, const struct cred *cred, uid_t uid);
gid_t user_ns_map_gid(struct user_namespace *to, const struct cred *cred, gid_t gid);
+int same_or_ancestor_user_ns(struct task_struct *task,
+ struct task_struct *victim);
+
#else
static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
@@ -66,6 +69,12 @@ static inline gid_t user_ns_map_gid(struct user_namespace *to,
return gid;
}
+static inline int same_or_ancestor_user_ns(struct task_struct *task,
+ struct task_struct *victim)
+{
+ return 1;
+}
+
#endif
#endif /* _LINUX_USER_H */
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 99bbaa3..ec7605d 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -134,21 +134,24 @@ int __ptrace_may_access(struct task_struct *task, unsigned int mode)
return 0;
rcu_read_lock();
tcred = __task_cred(task);
- if ((cred->uid != tcred->euid ||
- cred->uid != tcred->suid ||
- cred->uid != tcred->uid ||
- cred->gid != tcred->egid ||
- cred->gid != tcred->sgid ||
- cred->gid != tcred->gid) &&
- !capable(CAP_SYS_PTRACE)) {
- rcu_read_unlock();
- return -EPERM;
- }
+ if (cred->user->user_ns == tcred->user->user_ns &&
+ (cred->uid == tcred->euid &&
+ cred->uid == tcred->suid &&
+ cred->uid == tcred->uid &&
+ cred->gid == tcred->egid &&
+ cred->gid == tcred->sgid &&
+ cred->gid == tcred->gid))
+ goto ok;
+ if (ns_capable(tcred->user->user_ns, CAP_SYS_PTRACE))
+ goto ok;
+ rcu_read_unlock();
+ return -EPERM;
+ok:
rcu_read_unlock();
smp_rmb();
if (task->mm)
dumpable = get_dumpable(task->mm);
- if (!dumpable && !capable(CAP_SYS_PTRACE))
+ if (!dumpable && !task_ns_capable(task, CAP_SYS_PTRACE))
return -EPERM;
return security_ptrace_access_check(task, mode);
@@ -198,7 +201,7 @@ int ptrace_attach(struct task_struct *task)
goto unlock_tasklist;
task->ptrace = PT_PTRACED;
- if (capable(CAP_SYS_PTRACE))
+ if (task_ns_capable(task, CAP_SYS_PTRACE))
task->ptrace |= PT_PTRACE_CAP;
__ptrace_link(task, current);
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 2591583..4b70999 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -126,3 +126,19 @@ gid_t user_ns_map_gid(struct user_namespace *to, const struct cred *cred, gid_t
/* No useful relationship so no mapping */
return overflowgid;
}
+
+int same_or_ancestor_user_ns(struct task_struct *task,
+ struct task_struct *victim)
+{
+ struct user_namespace *u1 = task_cred_xxx(task, user)->user_ns;
+ struct user_namespace *u2 = task_cred_xxx(victim, user)->user_ns;
+ for (;;) {
+ if (u1 == u2)
+ return 1;
+ if (u1 == &init_user_ns)
+ return 0;
+ u1 = u1->creator->user_ns;
+ }
+ /* We never get here */
+ return 0;
+}
diff --git a/security/commoncap.c b/security/commoncap.c
index 9d910e6..0223096 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -130,18 +130,34 @@ int cap_settime(struct timespec *ts, struct timezone *tz)
* @child: The process to be accessed
* @mode: The mode of attachment.
*
+ * If we are in the same or an ancestor user_ns and have all the target
+ * task's capabilities, then ptrace access is allowed.
+ * If we have the ptrace capability to the target user_ns, then ptrace
+ * access is allowed.
+ * Else denied.
+ *
* Determine whether a process may access another, returning 0 if permission
* granted, -ve if denied.
*/
int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
{
int ret = 0;
+ const struct cred *cred, *tcred;
rcu_read_lock();
- if (!cap_issubset(__task_cred(child)->cap_permitted,
- current_cred()->cap_permitted) &&
- !capable(CAP_SYS_PTRACE))
- ret = -EPERM;
+ cred = current_cred();
+ tcred = __task_cred(child);
+ /*
+ * The ancestor user_ns check may be gratuitous, as I think
+ * we've already guaranteed that in kernel/ptrace.c.
+ */
+ if (same_or_ancestor_user_ns(current, child) &&
+ cap_issubset(tcred->cap_permitted, cred->cap_permitted))
+ goto out;
+ if (ns_capable(tcred->user->user_ns, CAP_SYS_PTRACE))
+ goto out;
+ ret = -EPERM;
+out:
rcu_read_unlock();
return ret;
}
@@ -150,18 +166,34 @@ int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
* cap_ptrace_traceme - Determine whether another process may trace the current
* @parent: The task proposed to be the tracer
*
+ * If parent is in the same or an ancestor user_ns and has all current's
+ * capabilities, then ptrace access is allowed.
+ * If parent has the ptrace capability to current's user_ns, then ptrace
+ * access is allowed.
+ * Else denied.
+ *
* Determine whether the nominated task is permitted to trace the current
* process, returning 0 if permission is granted, -ve if denied.
*/
int cap_ptrace_traceme(struct task_struct *parent)
{
int ret = 0;
+ const struct cred *cred, *tcred;
rcu_read_lock();
- if (!cap_issubset(current_cred()->cap_permitted,
- __task_cred(parent)->cap_permitted) &&
- !has_capability(parent, CAP_SYS_PTRACE))
- ret = -EPERM;
+ cred = __task_cred(parent);
+ tcred = current_cred();
+ /*
+ * The ancestor user_ns check may be gratuitous, as I think
+ * we've already guaranteed that in kernel/ptrace.c.
+ */
+ if (same_or_ancestor_user_ns(parent, current) &&
+ cap_issubset(tcred->cap_permitted, cred->cap_permitted))
+ goto out;
+ if (has_ns_capability(parent, tcred->user->user_ns, CAP_SYS_PTRACE))
+ goto out;
+ ret = -EPERM;
+out:
rcu_read_unlock();
return ret;
}
--
1.7.0.4
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [PATCH 05/08] Allow ptrace from non-init user namespaces
2011-01-11 6:44 ` [PATCH 05/08] Allow ptrace from non-init user namespaces Serge E. Hallyn
@ 2011-01-14 14:46 ` Bastian Blank
2011-01-14 15:00 ` Bastian Blank
2011-01-15 0:35 ` Serge E. Hallyn
0 siblings, 2 replies; 14+ messages in thread
From: Bastian Blank @ 2011-01-14 14:46 UTC (permalink / raw)
To: Serge E. Hallyn
Cc: containers, kernel list, LSM, Eric W. Biederman, Kees Cook,
Alexey Dobriyan, Michael Kerrisk
This mail did not show up in my inbox, even if I'm listed as receipient.
I only got a copy via the mailinglist.
On Tue, Jan 11, 2011 at 06:44:39AM +0000, Serge E. Hallyn wrote:
> diff --git a/kernel/ptrace.c b/kernel/ptrace.c
> index 99bbaa3..ec7605d 100644
> --- a/kernel/ptrace.c
> +++ b/kernel/ptrace.c
> @@ -134,21 +134,24 @@ int __ptrace_may_access(struct task_struct *task, unsigned int mode)
> return 0;
> rcu_read_lock();
> tcred = __task_cred(task);
> - if ((cred->uid != tcred->euid ||
> - cred->uid != tcred->suid ||
> - cred->uid != tcred->uid ||
> - cred->gid != tcred->egid ||
> - cred->gid != tcred->sgid ||
> - cred->gid != tcred->gid) &&
> - !capable(CAP_SYS_PTRACE)) {
> - rcu_read_unlock();
> - return -EPERM;
> - }
> + if (cred->user->user_ns == tcred->user->user_ns &&
> + (cred->uid == tcred->euid &&
> + cred->uid == tcred->suid &&
> + cred->uid == tcred->uid &&
> + cred->gid == tcred->egid &&
> + cred->gid == tcred->sgid &&
> + cred->gid == tcred->gid))
> + goto ok;
> + if (ns_capable(tcred->user->user_ns, CAP_SYS_PTRACE))
> + goto ok;
> + rcu_read_unlock();
> + return -EPERM;
> +ok:
This is wrong. Please move that out into functions if you are unable to
get the conditions right.
Bastian
--
If a man had a child who'd gone anti-social, killed perhaps, he'd still
tend to protect that child.
-- McCoy, "The Ultimate Computer", stardate 4731.3
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: [PATCH 05/08] Allow ptrace from non-init user namespaces
2011-01-14 14:46 ` Bastian Blank
@ 2011-01-14 15:00 ` Bastian Blank
2011-01-15 0:35 ` Serge E. Hallyn
1 sibling, 0 replies; 14+ messages in thread
From: Bastian Blank @ 2011-01-14 15:00 UTC (permalink / raw)
To: Serge E. Hallyn, containers, kernel list, LSM, Eric W. Biederman,
Kees Cook, Alexey Dobriyan, Michael Kerrisk
On Fri, Jan 14, 2011 at 03:46:09PM +0100, Bastian Blank wrote:
> On Tue, Jan 11, 2011 at 06:44:39AM +0000, Serge E. Hallyn wrote:
> > diff --git a/kernel/ptrace.c b/kernel/ptrace.c
> > index 99bbaa3..ec7605d 100644
> > --- a/kernel/ptrace.c
> > +++ b/kernel/ptrace.c
> > @@ -134,21 +134,24 @@ int __ptrace_may_access(struct task_struct *task, unsigned int mode)
> > return 0;
> > rcu_read_lock();
> > tcred = __task_cred(task);
> > - if ((cred->uid != tcred->euid ||
> > - cred->uid != tcred->suid ||
> > - cred->uid != tcred->uid ||
> > - cred->gid != tcred->egid ||
> > - cred->gid != tcred->sgid ||
> > - cred->gid != tcred->gid) &&
> > - !capable(CAP_SYS_PTRACE)) {
> > - rcu_read_unlock();
> > - return -EPERM;
> > - }
> > + if (cred->user->user_ns == tcred->user->user_ns &&
> > + (cred->uid == tcred->euid &&
> > + cred->uid == tcred->suid &&
> > + cred->uid == tcred->uid &&
> > + cred->gid == tcred->egid &&
> > + cred->gid == tcred->sgid &&
> > + cred->gid == tcred->gid))
> > + goto ok;
> > + if (ns_capable(tcred->user->user_ns, CAP_SYS_PTRACE))
> > + goto ok;
> > + rcu_read_unlock();
> > + return -EPERM;
> > +ok:
>
> This is wrong.
Whoops, it _is_ right. However the nested parenthes is unnecessary and
can lead to other conclusions.
Bastian
--
Lots of people drink from the wrong bottle sometimes.
-- Edith Keeler, "The City on the Edge of Forever",
stardate unknown
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: [PATCH 05/08] Allow ptrace from non-init user namespaces
2011-01-14 14:46 ` Bastian Blank
2011-01-14 15:00 ` Bastian Blank
@ 2011-01-15 0:35 ` Serge E. Hallyn
1 sibling, 0 replies; 14+ messages in thread
From: Serge E. Hallyn @ 2011-01-15 0:35 UTC (permalink / raw)
To: kernel list
Quoting Bastian Blank (bastian@waldi.eu.org):
> This mail did not show up in my inbox, even if I'm listed as receipient.
> I only got a copy via the mailinglist.
Yes, I always get errors sending to you:
<bastian@waldi.eu.org>: host mail.thinkmo.de[83.137.100.41] said: 504 5.5.2
<mail>: Helo command rejected: need fully-qualified hostname (in reply to
RCPT TO command)
(cc: list trimmed, hopefully this is the m-l you actually read :)
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH 06/08] user namespaces: convert all capable checks in kernel/sys.c
2011-01-11 6:43 userns: targeted capabilities v4 Serge E. Hallyn
` (4 preceding siblings ...)
2011-01-11 6:44 ` [PATCH 05/08] Allow ptrace from non-init user namespaces Serge E. Hallyn
@ 2011-01-11 6:44 ` Serge E. Hallyn
2011-01-11 6:45 ` [PATCH 07/08] user namespaces: convert several capable() calls Serge E. Hallyn
2011-01-11 6:45 ` [PATCH 08/08] userns: check user namespace for task->file uid equivalence checks Serge E. Hallyn
7 siblings, 0 replies; 14+ messages in thread
From: Serge E. Hallyn @ 2011-01-11 6:44 UTC (permalink / raw)
To: Serge E. Hallyn
Cc: LSM, James Morris, Kees Cook, containers, kernel list,
Eric W. Biederman, Alexey Dobriyan, Michael Kerrisk,
Bastian Blank
This allows setuid/setgid in containers. It also fixes some
corner cases where kernel logic foregoes capability checks when
uids are equivalent. The latter will need to be done throughout
the whole kernel.
Changelog:
Jan 11: Use nsown_capable() as suggested by Bastian Blank.
Jan 11: Fix logic errors in uid checks pointed out by Bastian.
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
---
kernel/sys.c | 67 +++++++++++++++++++++++++++++++++++----------------------
1 files changed, 41 insertions(+), 26 deletions(-)
diff --git a/kernel/sys.c b/kernel/sys.c
index 9b9b03b..b68cd67 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -116,17 +116,29 @@ EXPORT_SYMBOL(cad_pid);
void (*pm_power_off_prepare)(void);
+/* called with rcu_read_lock, creds are safe */
+static inline int set_one_prio_perm(struct task_struct *p)
+{
+ const struct cred *cred = current_cred(), *pcred = __task_cred(p);
+
+ if (pcred->user->user_ns == cred->user->user_ns &&
+ (pcred->uid == cred->euid ||
+ pcred->euid == cred->euid))
+ return 1;
+ if (ns_capable(pcred->user->user_ns, CAP_SYS_NICE))
+ return 1;
+ return 0;
+}
+
/*
* set the priority of a task
* - the caller must hold the RCU read lock
*/
static int set_one_prio(struct task_struct *p, int niceval, int error)
{
- const struct cred *cred = current_cred(), *pcred = __task_cred(p);
- int no_nice;
+ int ret, no_nice;
- if (pcred->uid != cred->euid &&
- pcred->euid != cred->euid && !capable(CAP_SYS_NICE)) {
+ if (!set_one_prio_perm(p)) {
error = -EPERM;
goto out;
}
@@ -496,7 +508,7 @@ SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
if (rgid != (gid_t) -1) {
if (old->gid == rgid ||
old->egid == rgid ||
- capable(CAP_SETGID))
+ nsown_capable(CAP_SETGID))
new->gid = rgid;
else
goto error;
@@ -505,7 +517,7 @@ SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
if (old->gid == egid ||
old->egid == egid ||
old->sgid == egid ||
- capable(CAP_SETGID))
+ nsown_capable(CAP_SETGID))
new->egid = egid;
else
goto error;
@@ -540,7 +552,7 @@ SYSCALL_DEFINE1(setgid, gid_t, gid)
old = current_cred();
retval = -EPERM;
- if (capable(CAP_SETGID))
+ if (nsown_capable(CAP_SETGID))
new->gid = new->egid = new->sgid = new->fsgid = gid;
else if (gid == old->gid || gid == old->sgid)
new->egid = new->fsgid = gid;
@@ -607,7 +619,7 @@ SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
new->uid = ruid;
if (old->uid != ruid &&
old->euid != ruid &&
- !capable(CAP_SETUID))
+ !nsown_capable(CAP_SETUID))
goto error;
}
@@ -616,7 +628,7 @@ SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
if (old->uid != euid &&
old->euid != euid &&
old->suid != euid &&
- !capable(CAP_SETUID))
+ !nsown_capable(CAP_SETUID))
goto error;
}
@@ -664,7 +676,7 @@ SYSCALL_DEFINE1(setuid, uid_t, uid)
old = current_cred();
retval = -EPERM;
- if (capable(CAP_SETUID)) {
+ if (nsown_capable(CAP_SETUID)) {
new->suid = new->uid = uid;
if (uid != old->uid) {
retval = set_user(new);
@@ -706,7 +718,7 @@ SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
old = current_cred();
retval = -EPERM;
- if (!capable(CAP_SETUID)) {
+ if (!nsown_capable(CAP_SETUID)) {
if (ruid != (uid_t) -1 && ruid != old->uid &&
ruid != old->euid && ruid != old->suid)
goto error;
@@ -770,7 +782,7 @@ SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid)
old = current_cred();
retval = -EPERM;
- if (!capable(CAP_SETGID)) {
+ if (!nsown_capable(CAP_SETGID)) {
if (rgid != (gid_t) -1 && rgid != old->gid &&
rgid != old->egid && rgid != old->sgid)
goto error;
@@ -830,7 +842,7 @@ SYSCALL_DEFINE1(setfsuid, uid_t, uid)
if (uid == old->uid || uid == old->euid ||
uid == old->suid || uid == old->fsuid ||
- capable(CAP_SETUID)) {
+ nsown_capable(CAP_SETUID)) {
if (uid != old_fsuid) {
new->fsuid = uid;
if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0)
@@ -863,7 +875,7 @@ SYSCALL_DEFINE1(setfsgid, gid_t, gid)
if (gid == old->gid || gid == old->egid ||
gid == old->sgid || gid == old->fsgid ||
- capable(CAP_SETGID)) {
+ nsown_capable(CAP_SETGID)) {
if (gid != old_fsgid) {
new->fsgid = gid;
goto change_okay;
@@ -1220,7 +1232,7 @@ SYSCALL_DEFINE2(setdomainname, char __user *, name, int, len)
int errno;
char tmp[__NEW_UTS_LEN];
- if (!capable(CAP_SYS_ADMIN))
+ if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
return -EPERM;
if (len < 0 || len > __NEW_UTS_LEN)
return -EINVAL;
@@ -1335,6 +1347,8 @@ int do_prlimit(struct task_struct *tsk, unsigned int resource,
rlim = tsk->signal->rlim + resource;
task_lock(tsk->group_leader);
if (new_rlim) {
+ /* Keep the capable check against init_user_ns until
+ cgroups can contain all limits */
if (new_rlim->rlim_max > rlim->rlim_max &&
!capable(CAP_SYS_RESOURCE))
retval = -EPERM;
@@ -1379,17 +1393,18 @@ static int check_prlimit_permission(struct task_struct *task)
const struct cred *cred = current_cred(), *tcred;
tcred = __task_cred(task);
- if ((cred->uid != tcred->euid ||
- cred->uid != tcred->suid ||
- cred->uid != tcred->uid ||
- cred->gid != tcred->egid ||
- cred->gid != tcred->sgid ||
- cred->gid != tcred->gid) &&
- !capable(CAP_SYS_RESOURCE)) {
- return -EPERM;
- }
-
- return 0;
+ if (cred->user->user_ns == tcred->user->user_ns &&
+ (cred->uid == tcred->euid &&
+ cred->uid == tcred->suid &&
+ cred->uid == tcred->uid &&
+ cred->gid == tcred->egid &&
+ cred->gid == tcred->sgid &&
+ cred->gid == tcred->gid))
+ return 0;
+ if (ns_capable(tcred->user->user_ns, CAP_SYS_RESOURCE))
+ return 0;
+
+ return -EPERM;
}
SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
--
1.7.0.4
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH 07/08] user namespaces: convert several capable() calls
2011-01-11 6:43 userns: targeted capabilities v4 Serge E. Hallyn
` (5 preceding siblings ...)
2011-01-11 6:44 ` [PATCH 06/08] user namespaces: convert all capable checks in kernel/sys.c Serge E. Hallyn
@ 2011-01-11 6:45 ` Serge E. Hallyn
2011-01-11 6:45 ` [PATCH 08/08] userns: check user namespace for task->file uid equivalence checks Serge E. Hallyn
7 siblings, 0 replies; 14+ messages in thread
From: Serge E. Hallyn @ 2011-01-11 6:45 UTC (permalink / raw)
To: Serge E. Hallyn
Cc: LSM, James Morris, Kees Cook, containers, kernel list,
Eric W. Biederman, Alexey Dobriyan, Michael Kerrisk,
Bastian Blank
CAP_IPC_OWNER and CAP_IPC_LOCK can be checked against current_user_ns(),
because the resource comes from current's own ipc namespace.
setuid/setgid are to uids in own namespace, so again checks can be
against current_user_ns().
Changelog:
Jan 11: Use task_ns_capable() in place of sched_capable().
Jan 11: Use nsown_capable() as suggested by Bastian Blank.
Jan 11: Clarify (hopefully) some logic in futex and sched.c
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
---
ipc/shm.c | 2 +-
ipc/util.c | 5 +++--
kernel/futex.c | 11 ++++++++++-
kernel/futex_compat.c | 11 ++++++++++-
kernel/groups.c | 2 +-
kernel/sched.c | 9 ++++++---
kernel/uid16.c | 2 +-
7 files changed, 32 insertions(+), 10 deletions(-)
diff --git a/ipc/shm.c b/ipc/shm.c
index 7d3bb22..b5a0c2b 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -773,7 +773,7 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
audit_ipc_obj(&(shp->shm_perm));
- if (!capable(CAP_IPC_LOCK)) {
+ if (!nsown_capable(CAP_IPC_LOCK)) {
uid_t euid = current_euid();
err = -EPERM;
if (euid != shp->shm_perm.uid &&
diff --git a/ipc/util.c b/ipc/util.c
index 69a0cc1..0bb65a6 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -627,7 +627,7 @@ int ipcperms (struct kern_ipc_perm *ipcp, short flag)
granted_mode >>= 3;
/* is there some bit set in requested_mode but not in granted_mode? */
if ((requested_mode & ~granted_mode & 0007) &&
- !capable(CAP_IPC_OWNER))
+ !nsown_capable(CAP_IPC_OWNER))
return -1;
return security_ipc_permission(ipcp, flag);
@@ -800,7 +800,8 @@ struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
euid = current_euid();
if (euid == ipcp->cuid ||
- euid == ipcp->uid || capable(CAP_SYS_ADMIN))
+ euid == ipcp->uid ||
+ nsown_capable(CAP_SYS_ADMIN))
return ipcp;
err = -EPERM;
diff --git a/kernel/futex.c b/kernel/futex.c
index 40a8777..f02cb1c 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2401,10 +2401,19 @@ SYSCALL_DEFINE3(get_robust_list, int, pid,
goto err_unlock;
ret = -EPERM;
pcred = __task_cred(p);
+ /* If victim is in different user_ns, then uids are not
+ comparable, so we must have CAP_SYS_PTRACE */
+ if (cred->user->user_ns != pcred->user->user_ns) {
+ if (!ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE))
+ goto err_unlock;
+ goto ok;
+ }
+ /* If victim is in same user_ns, then uids are comparable */
if (cred->euid != pcred->euid &&
cred->euid != pcred->uid &&
- !capable(CAP_SYS_PTRACE))
+ !ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE))
goto err_unlock;
+ok:
head = p->robust_list;
rcu_read_unlock();
}
diff --git a/kernel/futex_compat.c b/kernel/futex_compat.c
index a7934ac..5f9e689 100644
--- a/kernel/futex_compat.c
+++ b/kernel/futex_compat.c
@@ -153,10 +153,19 @@ compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr,
goto err_unlock;
ret = -EPERM;
pcred = __task_cred(p);
+ /* If victim is in different user_ns, then uids are not
+ comparable, so we must have CAP_SYS_PTRACE */
+ if (cred->user->user_ns != pcred->user->user_ns) {
+ if (!ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE))
+ goto err_unlock;
+ goto ok;
+ }
+ /* If victim is in same user_ns, then uids are comparable */
if (cred->euid != pcred->euid &&
cred->euid != pcred->uid &&
- !capable(CAP_SYS_PTRACE))
+ !ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE))
goto err_unlock;
+ok:
head = p->compat_robust_list;
rcu_read_unlock();
}
diff --git a/kernel/groups.c b/kernel/groups.c
index 253dc0f..1cc476d 100644
--- a/kernel/groups.c
+++ b/kernel/groups.c
@@ -233,7 +233,7 @@ SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
struct group_info *group_info;
int retval;
- if (!capable(CAP_SETGID))
+ if (!nsown_capable(CAP_SETGID))
return -EPERM;
if ((unsigned)gidsetsize > NGROUPS_MAX)
return -EINVAL;
diff --git a/kernel/sched.c b/kernel/sched.c
index 82c057c..cfd78e4 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4903,8 +4903,11 @@ static bool check_same_owner(struct task_struct *p)
rcu_read_lock();
pcred = __task_cred(p);
- match = (cred->euid == pcred->euid ||
- cred->euid == pcred->uid);
+ if (cred->user->user_ns == pcred->user->user_ns)
+ match = (cred->euid == pcred->euid ||
+ cred->euid == pcred->uid);
+ else
+ match = false;
rcu_read_unlock();
return match;
}
@@ -5229,7 +5232,7 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
goto out_free_cpus_allowed;
}
retval = -EPERM;
- if (!check_same_owner(p) && !capable(CAP_SYS_NICE))
+ if (!check_same_owner(p) && !task_ns_capable(p, CAP_SYS_NICE))
goto out_unlock;
retval = security_task_setscheduler(p);
diff --git a/kernel/uid16.c b/kernel/uid16.c
index 4192098..51c6e89 100644
--- a/kernel/uid16.c
+++ b/kernel/uid16.c
@@ -189,7 +189,7 @@ SYSCALL_DEFINE2(setgroups16, int, gidsetsize, old_gid_t __user *, grouplist)
struct group_info *group_info;
int retval;
- if (!capable(CAP_SETGID))
+ if (!nsown_capable(CAP_SETGID))
return -EPERM;
if ((unsigned)gidsetsize > NGROUPS_MAX)
return -EINVAL;
--
1.7.0.4
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH 08/08] userns: check user namespace for task->file uid equivalence checks
2011-01-11 6:43 userns: targeted capabilities v4 Serge E. Hallyn
` (6 preceding siblings ...)
2011-01-11 6:45 ` [PATCH 07/08] user namespaces: convert several capable() calls Serge E. Hallyn
@ 2011-01-11 6:45 ` Serge E. Hallyn
7 siblings, 0 replies; 14+ messages in thread
From: Serge E. Hallyn @ 2011-01-11 6:45 UTC (permalink / raw)
To: Serge E. Hallyn
Cc: LSM, James Morris, Kees Cook, containers, kernel list,
Eric W. Biederman, Alexey Dobriyan, Michael Kerrisk,
Bastian Blank
Cheat for now and say all files belong to init_user_ns. Next
step will be to let superblocks belong to a user_ns, and derive
inode_userns(inode) from inode->i_sb->s_user_ns. Finally we'll
introduce more flexible arrangements.
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
---
fs/inode.c | 17 +++++++++++++++++
fs/namei.c | 20 +++++++++++++++-----
include/linux/fs.h | 9 +++++++--
3 files changed, 39 insertions(+), 7 deletions(-)
diff --git a/fs/inode.c b/fs/inode.c
index 4a924c7..ebb2b85 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -25,6 +25,7 @@
#include <linux/async.h>
#include <linux/posix_acl.h>
#include <linux/ima.h>
+#include <linux/cred.h>
/*
* This is needed for the following functions:
@@ -1710,6 +1711,22 @@ void inode_init_owner(struct inode *inode, const struct inode *dir,
}
EXPORT_SYMBOL(inode_init_owner);
+/*
+ * return 1 if current either has CAP_FOWNER to the
+ * file, or owns the file.
+ */
+int is_owner_or_cap(struct inode *inode)
+{
+ struct user_namespace *ns = inode_userns(inode);
+
+ if (current_user_ns() == ns && current_fsuid() == inode->i_uid)
+ return 1;
+ if (ns_capable(ns, CAP_FOWNER))
+ return 1;
+ return 0;
+}
+EXPORT_SYMBOL(is_owner_or_cap);
+
#define CREATE_TRACE_POINTS
#include <trace/events/vfs.h>
diff --git a/fs/namei.c b/fs/namei.c
index b020c45..d956ce3 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -176,6 +176,9 @@ static int acl_permission_check(struct inode *inode, int mask,
mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
+ if (current_user_ns() != inode_userns(inode))
+ goto other_perms;
+
if (current_fsuid() == inode->i_uid)
mode >>= 6;
else {
@@ -189,6 +192,7 @@ static int acl_permission_check(struct inode *inode, int mask,
mode >>= 3;
}
+other_perms:
/*
* If the DACs are ok we don't need any capability check.
*/
@@ -225,7 +229,7 @@ int generic_permission(struct inode *inode, int mask,
* Executable DACs are overridable if at least one exec bit is set.
*/
if (!(mask & MAY_EXEC) || execute_ok(inode))
- if (capable(CAP_DAC_OVERRIDE))
+ if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
return 0;
/*
@@ -233,7 +237,7 @@ int generic_permission(struct inode *inode, int mask,
*/
mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
- if (capable(CAP_DAC_READ_SEARCH))
+ if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
return 0;
return -EACCES;
@@ -463,6 +467,7 @@ force_reval_path(struct path *path, struct nameidata *nd)
static int exec_permission(struct inode *inode)
{
int ret;
+ struct user_namespace *ns = inode_userns(inode);
if (inode->i_op->permission) {
ret = inode->i_op->permission(inode, MAY_EXEC);
@@ -474,7 +479,7 @@ static int exec_permission(struct inode *inode)
if (!ret)
goto ok;
- if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH))
+ if (ns_capable(ns, CAP_DAC_OVERRIDE) || ns_capable(ns, CAP_DAC_READ_SEARCH))
goto ok;
return ret;
@@ -1262,11 +1267,15 @@ static inline int check_sticky(struct inode *dir, struct inode *inode)
if (!(dir->i_mode & S_ISVTX))
return 0;
+ if (current_user_ns() != inode_userns(inode))
+ goto other_userns;
if (inode->i_uid == fsuid)
return 0;
if (dir->i_uid == fsuid)
return 0;
- return !capable(CAP_FOWNER);
+
+other_userns:
+ return !ns_capable(inode_userns(inode), CAP_FOWNER);
}
/*
@@ -1954,7 +1963,8 @@ int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
if (error)
return error;
- if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
+ if ((S_ISCHR(mode) || S_ISBLK(mode)) &&
+ !ns_capable(inode_userns(dir), CAP_MKNOD))
return -EPERM;
if (!dir->i_op->mknod)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 090f0ea..674c06a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1437,8 +1437,13 @@ enum {
#define put_fs_excl() atomic_dec(¤t->fs_excl)
#define has_fs_excl() atomic_read(¤t->fs_excl)
-#define is_owner_or_cap(inode) \
- ((current_fsuid() == (inode)->i_uid) || capable(CAP_FOWNER))
+/*
+ * until VFS tracks user namespaces for inodes, just make all files
+ * belong to init_user_ns
+ */
+extern struct user_namespace init_user_ns;
+#define inode_userns(inode) (&init_user_ns)
+extern int is_owner_or_cap(struct inode *inode);
/* not quite ready to be deprecated, but... */
extern void lock_super(struct super_block *);
--
1.7.0.4
^ permalink raw reply related [flat|nested] 14+ messages in thread