diff options
Diffstat (limited to 'security/commoncap.c')
| -rw-r--r-- | security/commoncap.c | 78 |
1 files changed, 63 insertions, 15 deletions
diff --git a/security/commoncap.c b/security/commoncap.c index 49c57fd60aea..f20e984ccfb4 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 @@ -67,6 +68,7 @@ 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 * @@ -78,10 +80,30 @@ 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 != &init_user_ns && 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 a capability in a parent user ns, then you have + * it over all children user namespaces as well. + */ + targ_ns = targ_ns->creator->user_ns; + } + + /* We never get here */ } /** @@ -105,18 +127,30 @@ int cap_settime(const struct timespec *ts, const 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, *child_cred; rcu_read_lock(); - if (!cap_issubset(__task_cred(child)->cap_permitted, - current_cred()->cap_permitted) && - !capable(CAP_SYS_PTRACE)) - ret = -EPERM; + cred = current_cred(); + child_cred = __task_cred(child); + if (cred->user->user_ns == child_cred->user->user_ns && + cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) + goto out; + if (ns_capable(child_cred->user->user_ns, CAP_SYS_PTRACE)) + goto out; + ret = -EPERM; +out: rcu_read_unlock(); return ret; } @@ -125,18 +159,30 @@ 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, *child_cred; 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); + child_cred = current_cred(); + if (cred->user->user_ns == child_cred->user->user_ns && + cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) + goto out; + if (has_ns_capability(parent, child_cred->user->user_ns, CAP_SYS_PTRACE)) + goto out; + ret = -EPERM; +out: rcu_read_unlock(); return ret; } @@ -176,7 +222,8 @@ 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; @@ -828,7 +875,8 @@ 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 @@ -893,7 +941,7 @@ 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); @@ -920,7 +968,7 @@ 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) |