From 3486740a4f32a6a466f5ac931654d154790ba648 Mon Sep 17 00:00:00 2001 From: "Serge E. Hallyn" Date: Wed, 23 Mar 2011 16:43:17 -0700 Subject: userns: security: make capabilities relative to the user namespace - 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 02/16/2011: [serge] fix a logic bug: the root user is always creator of init_user_ns, but should not always have capabilities to it! Fix the check in cap_capable(). 02/21/2011: Add the required user_ns parameter to security_capable, fixing a compile failure. 02/23/2011: Convert some macros to functions as per akpm comments. Some couldn't be converted because we can't easily forward-declare them (they are inline if !SECURITY, extern if SECURITY). Add a current_user_ns function so we can use it in capability.h without #including cred.h. Move all forward declarations together to the top of the #ifdef __KERNEL__ section, and use kernel-doc format. 02/23/2011: Per dhowells, clean up comment in cap_capable(). 02/23/2011: Per akpm, remove unreachable 'return -EPERM' in cap_capable. (Original written and signed off by Eric; latest, modified version acked by him) [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: export current_user_ns() for ecryptfs] [serge.hallyn@canonical.com: remove unneeded extra argument in selinux's task_has_capability] Signed-off-by: Eric W. Biederman Signed-off-by: Serge E. Hallyn Acked-by: "Eric W. Biederman" Acked-by: Daniel Lezcano Acked-by: David Howells Cc: James Morris Signed-off-by: Serge E. Hallyn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/security.h | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) (limited to 'include/linux/security.h') diff --git a/include/linux/security.h b/include/linux/security.h index 56cac520d01..ca02f171673 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -47,13 +47,14 @@ 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(const struct timespec *ts, const 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); @@ -1262,6 +1263,7 @@ 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 . * @audit: Whether to write an audit message or not * Return 0 if the capability is granted for @tsk. @@ -1384,7 +1386,7 @@ 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 (*quotactl) (int cmds, int type, int id, struct super_block *sb); int (*quota_on) (struct dentry *dentry); int (*syslog) (int type); @@ -1665,9 +1667,12 @@ 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(const struct cred *cred, 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, const struct cred *cred, + 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_quotactl(int cmds, int type, int id, struct super_block *sb); int security_quota_on(struct dentry *dentry); int security_syslog(int type); @@ -1860,28 +1865,29 @@ static inline int security_capset(struct cred *new, return cap_capset(new, old, effective, inheritable, permitted); } -static inline int security_capable(const struct cred *cred, int cap) +static inline int security_capable(struct user_namespace *ns, + const struct cred *cred, int cap) { - return cap_capable(current, cred, cap, SECURITY_CAP_AUDIT); + return cap_capable(current, cred, 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; -- cgit v1.2.3-70-g09d2