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1480 lines
43 KiB
1480 lines
43 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* Common capabilities, needed by capability.o. |
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*/ |
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|
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#include <linux/capability.h> |
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#include <linux/audit.h> |
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#include <linux/init.h> |
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#include <linux/kernel.h> |
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#include <linux/lsm_hooks.h> |
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#include <linux/file.h> |
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#include <linux/mm.h> |
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#include <linux/mman.h> |
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#include <linux/pagemap.h> |
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#include <linux/swap.h> |
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#include <linux/skbuff.h> |
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#include <linux/netlink.h> |
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#include <linux/ptrace.h> |
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#include <linux/xattr.h> |
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#include <linux/hugetlb.h> |
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#include <linux/mount.h> |
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#include <linux/sched.h> |
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#include <linux/prctl.h> |
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#include <linux/securebits.h> |
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#include <linux/user_namespace.h> |
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#include <linux/binfmts.h> |
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#include <linux/personality.h> |
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|
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/* |
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* If a non-root user executes a setuid-root binary in |
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* !secure(SECURE_NOROOT) mode, then we raise capabilities. |
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* However if fE is also set, then the intent is for only |
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* the file capabilities to be applied, and the setuid-root |
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* bit is left on either to change the uid (plausible) or |
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* to get full privilege on a kernel without file capabilities |
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* support. So in that case we do not raise capabilities. |
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* |
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* Warn if that happens, once per boot. |
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*/ |
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static void warn_setuid_and_fcaps_mixed(const char *fname) |
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{ |
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static int warned; |
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if (!warned) { |
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printk(KERN_INFO "warning: `%s' has both setuid-root and" |
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" effective capabilities. Therefore not raising all" |
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" capabilities.\n", fname); |
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warned = 1; |
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} |
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} |
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|
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/** |
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* cap_capable - Determine whether a task has a particular effective capability |
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* @cred: The credentials to use |
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* @targ_ns: The user namespace in which we need the capability |
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* @cap: The capability to check for |
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* @opts: Bitmask of options defined in include/linux/security.h |
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* |
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* Determine whether the nominated task has the specified capability amongst |
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* its effective set, returning 0 if it does, -ve if it does not. |
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* |
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* NOTE WELL: cap_has_capability() cannot be used like the kernel's capable() |
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* and has_capability() functions. That is, it has the reverse semantics: |
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* cap_has_capability() returns 0 when a task has a capability, but the |
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* kernel's capable() and has_capability() returns 1 for this case. |
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*/ |
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int cap_capable(const struct cred *cred, struct user_namespace *targ_ns, |
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int cap, unsigned int opts) |
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{ |
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struct user_namespace *ns = targ_ns; |
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|
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/* See if cred has the capability in the target user namespace |
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* by examining the target user namespace and all of the target |
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* user namespace's parents. |
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*/ |
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for (;;) { |
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/* Do we have the necessary capabilities? */ |
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if (ns == cred->user_ns) |
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return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM; |
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|
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/* |
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* If we're already at a lower level than we're looking for, |
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* we're done searching. |
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*/ |
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if (ns->level <= cred->user_ns->level) |
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return -EPERM; |
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|
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/* |
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* The owner of the user namespace in the parent of the |
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* user namespace has all caps. |
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*/ |
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if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid)) |
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return 0; |
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|
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/* |
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* If you have a capability in a parent user ns, then you have |
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* it over all children user namespaces as well. |
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*/ |
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ns = ns->parent; |
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} |
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|
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/* We never get here */ |
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} |
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|
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/** |
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* cap_settime - Determine whether the current process may set the system clock |
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* @ts: The time to set |
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* @tz: The timezone to set |
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* |
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* Determine whether the current process may set the system clock and timezone |
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* information, returning 0 if permission granted, -ve if denied. |
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*/ |
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int cap_settime(const struct timespec64 *ts, const struct timezone *tz) |
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{ |
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if (!capable(CAP_SYS_TIME)) |
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return -EPERM; |
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return 0; |
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} |
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|
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/** |
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* cap_ptrace_access_check - Determine whether the current process may access |
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* another |
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* @child: The process to be accessed |
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* @mode: The mode of attachment. |
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* |
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* If we are in the same or an ancestor user_ns and have all the target |
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* task's capabilities, then ptrace access is allowed. |
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* If we have the ptrace capability to the target user_ns, then ptrace |
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* access is allowed. |
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* Else denied. |
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* |
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* Determine whether a process may access another, returning 0 if permission |
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* granted, -ve if denied. |
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*/ |
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int cap_ptrace_access_check(struct task_struct *child, unsigned int mode) |
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{ |
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int ret = 0; |
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const struct cred *cred, *child_cred; |
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const kernel_cap_t *caller_caps; |
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|
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rcu_read_lock(); |
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cred = current_cred(); |
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child_cred = __task_cred(child); |
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if (mode & PTRACE_MODE_FSCREDS) |
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caller_caps = &cred->cap_effective; |
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else |
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caller_caps = &cred->cap_permitted; |
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if (cred->user_ns == child_cred->user_ns && |
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cap_issubset(child_cred->cap_permitted, *caller_caps)) |
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goto out; |
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if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE)) |
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goto out; |
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ret = -EPERM; |
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out: |
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rcu_read_unlock(); |
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return ret; |
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} |
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|
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/** |
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* cap_ptrace_traceme - Determine whether another process may trace the current |
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* @parent: The task proposed to be the tracer |
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* |
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* If parent is in the same or an ancestor user_ns and has all current's |
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* capabilities, then ptrace access is allowed. |
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* If parent has the ptrace capability to current's user_ns, then ptrace |
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* access is allowed. |
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* Else denied. |
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* |
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* Determine whether the nominated task is permitted to trace the current |
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* process, returning 0 if permission is granted, -ve if denied. |
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*/ |
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int cap_ptrace_traceme(struct task_struct *parent) |
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{ |
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int ret = 0; |
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const struct cred *cred, *child_cred; |
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|
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rcu_read_lock(); |
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cred = __task_cred(parent); |
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child_cred = current_cred(); |
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if (cred->user_ns == child_cred->user_ns && |
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cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) |
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goto out; |
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if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE)) |
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goto out; |
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ret = -EPERM; |
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out: |
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rcu_read_unlock(); |
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return ret; |
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} |
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|
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/** |
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* cap_capget - Retrieve a task's capability sets |
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* @target: The task from which to retrieve the capability sets |
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* @effective: The place to record the effective set |
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* @inheritable: The place to record the inheritable set |
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* @permitted: The place to record the permitted set |
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* |
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* This function retrieves the capabilities of the nominated task and returns |
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* them to the caller. |
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*/ |
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int cap_capget(struct task_struct *target, kernel_cap_t *effective, |
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kernel_cap_t *inheritable, kernel_cap_t *permitted) |
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{ |
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const struct cred *cred; |
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|
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/* Derived from kernel/capability.c:sys_capget. */ |
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rcu_read_lock(); |
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cred = __task_cred(target); |
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*effective = cred->cap_effective; |
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*inheritable = cred->cap_inheritable; |
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*permitted = cred->cap_permitted; |
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rcu_read_unlock(); |
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return 0; |
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} |
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|
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/* |
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* Determine whether the inheritable capabilities are limited to the old |
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* permitted set. Returns 1 if they are limited, 0 if they are not. |
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*/ |
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static inline int cap_inh_is_capped(void) |
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{ |
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/* they are so limited unless the current task has the CAP_SETPCAP |
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* capability |
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*/ |
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if (cap_capable(current_cred(), current_cred()->user_ns, |
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CAP_SETPCAP, CAP_OPT_NONE) == 0) |
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return 0; |
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return 1; |
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} |
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|
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/** |
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* cap_capset - Validate and apply proposed changes to current's capabilities |
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* @new: The proposed new credentials; alterations should be made here |
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* @old: The current task's current credentials |
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* @effective: A pointer to the proposed new effective capabilities set |
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* @inheritable: A pointer to the proposed new inheritable capabilities set |
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* @permitted: A pointer to the proposed new permitted capabilities set |
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* |
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* This function validates and applies a proposed mass change to the current |
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* process's capability sets. The changes are made to the proposed new |
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* credentials, and assuming no error, will be committed by the caller of LSM. |
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*/ |
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int cap_capset(struct cred *new, |
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const struct cred *old, |
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const kernel_cap_t *effective, |
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const kernel_cap_t *inheritable, |
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const kernel_cap_t *permitted) |
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{ |
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if (cap_inh_is_capped() && |
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!cap_issubset(*inheritable, |
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cap_combine(old->cap_inheritable, |
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old->cap_permitted))) |
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/* incapable of using this inheritable set */ |
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return -EPERM; |
|
|
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if (!cap_issubset(*inheritable, |
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cap_combine(old->cap_inheritable, |
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old->cap_bset))) |
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/* no new pI capabilities outside bounding set */ |
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return -EPERM; |
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|
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/* verify restrictions on target's new Permitted set */ |
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if (!cap_issubset(*permitted, old->cap_permitted)) |
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return -EPERM; |
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|
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/* verify the _new_Effective_ is a subset of the _new_Permitted_ */ |
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if (!cap_issubset(*effective, *permitted)) |
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return -EPERM; |
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|
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new->cap_effective = *effective; |
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new->cap_inheritable = *inheritable; |
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new->cap_permitted = *permitted; |
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|
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/* |
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* Mask off ambient bits that are no longer both permitted and |
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* inheritable. |
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*/ |
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new->cap_ambient = cap_intersect(new->cap_ambient, |
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cap_intersect(*permitted, |
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*inheritable)); |
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if (WARN_ON(!cap_ambient_invariant_ok(new))) |
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return -EINVAL; |
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return 0; |
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} |
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|
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/** |
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* cap_inode_need_killpriv - Determine if inode change affects privileges |
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* @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV |
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* |
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* Determine if an inode having a change applied that's marked ATTR_KILL_PRIV |
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* affects the security markings on that inode, and if it is, should |
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* inode_killpriv() be invoked or the change rejected. |
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* |
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* Return: 1 if security.capability has a value, meaning inode_killpriv() |
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* is required, 0 otherwise, meaning inode_killpriv() is not required. |
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*/ |
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int cap_inode_need_killpriv(struct dentry *dentry) |
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{ |
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struct inode *inode = d_backing_inode(dentry); |
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int error; |
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|
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error = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0); |
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return error > 0; |
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} |
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|
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/** |
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* cap_inode_killpriv - Erase the security markings on an inode |
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* |
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* @mnt_userns: user namespace of the mount the inode was found from |
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* @dentry: The inode/dentry to alter |
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* |
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* Erase the privilege-enhancing security markings on an inode. |
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* |
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* If the inode has been found through an idmapped mount the user namespace of |
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* the vfsmount must be passed through @mnt_userns. This function will then |
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* take care to map the inode according to @mnt_userns before checking |
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* permissions. On non-idmapped mounts or if permission checking is to be |
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* performed on the raw inode simply passs init_user_ns. |
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* |
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* Return: 0 if successful, -ve on error. |
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*/ |
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int cap_inode_killpriv(struct user_namespace *mnt_userns, struct dentry *dentry) |
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{ |
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int error; |
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|
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error = __vfs_removexattr(mnt_userns, dentry, XATTR_NAME_CAPS); |
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if (error == -EOPNOTSUPP) |
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error = 0; |
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return error; |
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} |
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|
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static bool rootid_owns_currentns(kuid_t kroot) |
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{ |
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struct user_namespace *ns; |
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|
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if (!uid_valid(kroot)) |
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return false; |
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|
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for (ns = current_user_ns(); ; ns = ns->parent) { |
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if (from_kuid(ns, kroot) == 0) |
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return true; |
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if (ns == &init_user_ns) |
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break; |
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} |
|
|
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return false; |
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} |
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|
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static __u32 sansflags(__u32 m) |
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{ |
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return m & ~VFS_CAP_FLAGS_EFFECTIVE; |
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} |
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|
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static bool is_v2header(size_t size, const struct vfs_cap_data *cap) |
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{ |
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if (size != XATTR_CAPS_SZ_2) |
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return false; |
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return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_2; |
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} |
|
|
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static bool is_v3header(size_t size, const struct vfs_cap_data *cap) |
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{ |
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if (size != XATTR_CAPS_SZ_3) |
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return false; |
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return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_3; |
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} |
|
|
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/* |
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* getsecurity: We are called for security.* before any attempt to read the |
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* xattr from the inode itself. |
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* |
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* This gives us a chance to read the on-disk value and convert it. If we |
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* return -EOPNOTSUPP, then vfs_getxattr() will call the i_op handler. |
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* |
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* Note we are not called by vfs_getxattr_alloc(), but that is only called |
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* by the integrity subsystem, which really wants the unconverted values - |
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* so that's good. |
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*/ |
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int cap_inode_getsecurity(struct user_namespace *mnt_userns, |
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struct inode *inode, const char *name, void **buffer, |
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bool alloc) |
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{ |
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int size, ret; |
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kuid_t kroot; |
|
u32 nsmagic, magic; |
|
uid_t root, mappedroot; |
|
char *tmpbuf = NULL; |
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struct vfs_cap_data *cap; |
|
struct vfs_ns_cap_data *nscap = NULL; |
|
struct dentry *dentry; |
|
struct user_namespace *fs_ns; |
|
|
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if (strcmp(name, "capability") != 0) |
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return -EOPNOTSUPP; |
|
|
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dentry = d_find_any_alias(inode); |
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if (!dentry) |
|
return -EINVAL; |
|
|
|
size = sizeof(struct vfs_ns_cap_data); |
|
ret = (int)vfs_getxattr_alloc(mnt_userns, dentry, XATTR_NAME_CAPS, |
|
&tmpbuf, size, GFP_NOFS); |
|
dput(dentry); |
|
|
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if (ret < 0 || !tmpbuf) |
|
return ret; |
|
|
|
fs_ns = inode->i_sb->s_user_ns; |
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cap = (struct vfs_cap_data *) tmpbuf; |
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if (is_v2header((size_t) ret, cap)) { |
|
root = 0; |
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} else if (is_v3header((size_t) ret, cap)) { |
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nscap = (struct vfs_ns_cap_data *) tmpbuf; |
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root = le32_to_cpu(nscap->rootid); |
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} else { |
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size = -EINVAL; |
|
goto out_free; |
|
} |
|
|
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kroot = make_kuid(fs_ns, root); |
|
|
|
/* If this is an idmapped mount shift the kuid. */ |
|
kroot = kuid_into_mnt(mnt_userns, kroot); |
|
|
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/* If the root kuid maps to a valid uid in current ns, then return |
|
* this as a nscap. */ |
|
mappedroot = from_kuid(current_user_ns(), kroot); |
|
if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) { |
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size = sizeof(struct vfs_ns_cap_data); |
|
if (alloc) { |
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if (!nscap) { |
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/* v2 -> v3 conversion */ |
|
nscap = kzalloc(size, GFP_ATOMIC); |
|
if (!nscap) { |
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size = -ENOMEM; |
|
goto out_free; |
|
} |
|
nsmagic = VFS_CAP_REVISION_3; |
|
magic = le32_to_cpu(cap->magic_etc); |
|
if (magic & VFS_CAP_FLAGS_EFFECTIVE) |
|
nsmagic |= VFS_CAP_FLAGS_EFFECTIVE; |
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memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); |
|
nscap->magic_etc = cpu_to_le32(nsmagic); |
|
} else { |
|
/* use allocated v3 buffer */ |
|
tmpbuf = NULL; |
|
} |
|
nscap->rootid = cpu_to_le32(mappedroot); |
|
*buffer = nscap; |
|
} |
|
goto out_free; |
|
} |
|
|
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if (!rootid_owns_currentns(kroot)) { |
|
size = -EOVERFLOW; |
|
goto out_free; |
|
} |
|
|
|
/* This comes from a parent namespace. Return as a v2 capability */ |
|
size = sizeof(struct vfs_cap_data); |
|
if (alloc) { |
|
if (nscap) { |
|
/* v3 -> v2 conversion */ |
|
cap = kzalloc(size, GFP_ATOMIC); |
|
if (!cap) { |
|
size = -ENOMEM; |
|
goto out_free; |
|
} |
|
magic = VFS_CAP_REVISION_2; |
|
nsmagic = le32_to_cpu(nscap->magic_etc); |
|
if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE) |
|
magic |= VFS_CAP_FLAGS_EFFECTIVE; |
|
memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32); |
|
cap->magic_etc = cpu_to_le32(magic); |
|
} else { |
|
/* use unconverted v2 */ |
|
tmpbuf = NULL; |
|
} |
|
*buffer = cap; |
|
} |
|
out_free: |
|
kfree(tmpbuf); |
|
return size; |
|
} |
|
|
|
/** |
|
* rootid_from_xattr - translate root uid of vfs caps |
|
* |
|
* @value: vfs caps value which may be modified by this function |
|
* @size: size of @ivalue |
|
* @task_ns: user namespace of the caller |
|
* @mnt_userns: user namespace of the mount the inode was found from |
|
* |
|
* If the inode has been found through an idmapped mount the user namespace of |
|
* the vfsmount must be passed through @mnt_userns. This function will then |
|
* take care to map the inode according to @mnt_userns before checking |
|
* permissions. On non-idmapped mounts or if permission checking is to be |
|
* performed on the raw inode simply passs init_user_ns. |
|
*/ |
|
static kuid_t rootid_from_xattr(const void *value, size_t size, |
|
struct user_namespace *task_ns, |
|
struct user_namespace *mnt_userns) |
|
{ |
|
const struct vfs_ns_cap_data *nscap = value; |
|
kuid_t rootkid; |
|
uid_t rootid = 0; |
|
|
|
if (size == XATTR_CAPS_SZ_3) |
|
rootid = le32_to_cpu(nscap->rootid); |
|
|
|
rootkid = make_kuid(task_ns, rootid); |
|
return kuid_from_mnt(mnt_userns, rootkid); |
|
} |
|
|
|
static bool validheader(size_t size, const struct vfs_cap_data *cap) |
|
{ |
|
return is_v2header(size, cap) || is_v3header(size, cap); |
|
} |
|
|
|
/** |
|
* cap_convert_nscap - check vfs caps |
|
* |
|
* @mnt_userns: user namespace of the mount the inode was found from |
|
* @dentry: used to retrieve inode to check permissions on |
|
* @ivalue: vfs caps value which may be modified by this function |
|
* @size: size of @ivalue |
|
* |
|
* User requested a write of security.capability. If needed, update the |
|
* xattr to change from v2 to v3, or to fixup the v3 rootid. |
|
* |
|
* If the inode has been found through an idmapped mount the user namespace of |
|
* the vfsmount must be passed through @mnt_userns. This function will then |
|
* take care to map the inode according to @mnt_userns before checking |
|
* permissions. On non-idmapped mounts or if permission checking is to be |
|
* performed on the raw inode simply passs init_user_ns. |
|
* |
|
* Return: On success, return the new size; on error, return < 0. |
|
*/ |
|
int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry, |
|
const void **ivalue, size_t size) |
|
{ |
|
struct vfs_ns_cap_data *nscap; |
|
uid_t nsrootid; |
|
const struct vfs_cap_data *cap = *ivalue; |
|
__u32 magic, nsmagic; |
|
struct inode *inode = d_backing_inode(dentry); |
|
struct user_namespace *task_ns = current_user_ns(), |
|
*fs_ns = inode->i_sb->s_user_ns; |
|
kuid_t rootid; |
|
size_t newsize; |
|
|
|
if (!*ivalue) |
|
return -EINVAL; |
|
if (!validheader(size, cap)) |
|
return -EINVAL; |
|
if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP)) |
|
return -EPERM; |
|
if (size == XATTR_CAPS_SZ_2 && (mnt_userns == &init_user_ns)) |
|
if (ns_capable(inode->i_sb->s_user_ns, CAP_SETFCAP)) |
|
/* user is privileged, just write the v2 */ |
|
return size; |
|
|
|
rootid = rootid_from_xattr(*ivalue, size, task_ns, mnt_userns); |
|
if (!uid_valid(rootid)) |
|
return -EINVAL; |
|
|
|
nsrootid = from_kuid(fs_ns, rootid); |
|
if (nsrootid == -1) |
|
return -EINVAL; |
|
|
|
newsize = sizeof(struct vfs_ns_cap_data); |
|
nscap = kmalloc(newsize, GFP_ATOMIC); |
|
if (!nscap) |
|
return -ENOMEM; |
|
nscap->rootid = cpu_to_le32(nsrootid); |
|
nsmagic = VFS_CAP_REVISION_3; |
|
magic = le32_to_cpu(cap->magic_etc); |
|
if (magic & VFS_CAP_FLAGS_EFFECTIVE) |
|
nsmagic |= VFS_CAP_FLAGS_EFFECTIVE; |
|
nscap->magic_etc = cpu_to_le32(nsmagic); |
|
memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); |
|
|
|
*ivalue = nscap; |
|
return newsize; |
|
} |
|
|
|
/* |
|
* Calculate the new process capability sets from the capability sets attached |
|
* to a file. |
|
*/ |
|
static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps, |
|
struct linux_binprm *bprm, |
|
bool *effective, |
|
bool *has_fcap) |
|
{ |
|
struct cred *new = bprm->cred; |
|
unsigned i; |
|
int ret = 0; |
|
|
|
if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE) |
|
*effective = true; |
|
|
|
if (caps->magic_etc & VFS_CAP_REVISION_MASK) |
|
*has_fcap = true; |
|
|
|
CAP_FOR_EACH_U32(i) { |
|
__u32 permitted = caps->permitted.cap[i]; |
|
__u32 inheritable = caps->inheritable.cap[i]; |
|
|
|
/* |
|
* pP' = (X & fP) | (pI & fI) |
|
* The addition of pA' is handled later. |
|
*/ |
|
new->cap_permitted.cap[i] = |
|
(new->cap_bset.cap[i] & permitted) | |
|
(new->cap_inheritable.cap[i] & inheritable); |
|
|
|
if (permitted & ~new->cap_permitted.cap[i]) |
|
/* insufficient to execute correctly */ |
|
ret = -EPERM; |
|
} |
|
|
|
/* |
|
* For legacy apps, with no internal support for recognizing they |
|
* do not have enough capabilities, we return an error if they are |
|
* missing some "forced" (aka file-permitted) capabilities. |
|
*/ |
|
return *effective ? ret : 0; |
|
} |
|
|
|
/** |
|
* get_vfs_caps_from_disk - retrieve vfs caps from disk |
|
* |
|
* @mnt_userns: user namespace of the mount the inode was found from |
|
* @dentry: dentry from which @inode is retrieved |
|
* @cpu_caps: vfs capabilities |
|
* |
|
* Extract the on-exec-apply capability sets for an executable file. |
|
* |
|
* If the inode has been found through an idmapped mount the user namespace of |
|
* the vfsmount must be passed through @mnt_userns. This function will then |
|
* take care to map the inode according to @mnt_userns before checking |
|
* permissions. On non-idmapped mounts or if permission checking is to be |
|
* performed on the raw inode simply passs init_user_ns. |
|
*/ |
|
int get_vfs_caps_from_disk(struct user_namespace *mnt_userns, |
|
const struct dentry *dentry, |
|
struct cpu_vfs_cap_data *cpu_caps) |
|
{ |
|
struct inode *inode = d_backing_inode(dentry); |
|
__u32 magic_etc; |
|
unsigned tocopy, i; |
|
int size; |
|
struct vfs_ns_cap_data data, *nscaps = &data; |
|
struct vfs_cap_data *caps = (struct vfs_cap_data *) &data; |
|
kuid_t rootkuid; |
|
struct user_namespace *fs_ns; |
|
|
|
memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data)); |
|
|
|
if (!inode) |
|
return -ENODATA; |
|
|
|
fs_ns = inode->i_sb->s_user_ns; |
|
size = __vfs_getxattr((struct dentry *)dentry, inode, |
|
XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ); |
|
if (size == -ENODATA || size == -EOPNOTSUPP) |
|
/* no data, that's ok */ |
|
return -ENODATA; |
|
|
|
if (size < 0) |
|
return size; |
|
|
|
if (size < sizeof(magic_etc)) |
|
return -EINVAL; |
|
|
|
cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps->magic_etc); |
|
|
|
rootkuid = make_kuid(fs_ns, 0); |
|
switch (magic_etc & VFS_CAP_REVISION_MASK) { |
|
case VFS_CAP_REVISION_1: |
|
if (size != XATTR_CAPS_SZ_1) |
|
return -EINVAL; |
|
tocopy = VFS_CAP_U32_1; |
|
break; |
|
case VFS_CAP_REVISION_2: |
|
if (size != XATTR_CAPS_SZ_2) |
|
return -EINVAL; |
|
tocopy = VFS_CAP_U32_2; |
|
break; |
|
case VFS_CAP_REVISION_3: |
|
if (size != XATTR_CAPS_SZ_3) |
|
return -EINVAL; |
|
tocopy = VFS_CAP_U32_3; |
|
rootkuid = make_kuid(fs_ns, le32_to_cpu(nscaps->rootid)); |
|
break; |
|
|
|
default: |
|
return -EINVAL; |
|
} |
|
/* Limit the caps to the mounter of the filesystem |
|
* or the more limited uid specified in the xattr. |
|
*/ |
|
rootkuid = kuid_into_mnt(mnt_userns, rootkuid); |
|
if (!rootid_owns_currentns(rootkuid)) |
|
return -ENODATA; |
|
|
|
CAP_FOR_EACH_U32(i) { |
|
if (i >= tocopy) |
|
break; |
|
cpu_caps->permitted.cap[i] = le32_to_cpu(caps->data[i].permitted); |
|
cpu_caps->inheritable.cap[i] = le32_to_cpu(caps->data[i].inheritable); |
|
} |
|
|
|
cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; |
|
cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; |
|
|
|
cpu_caps->rootid = rootkuid; |
|
|
|
return 0; |
|
} |
|
|
|
/* |
|
* Attempt to get the on-exec apply capability sets for an executable file from |
|
* its xattrs and, if present, apply them to the proposed credentials being |
|
* constructed by execve(). |
|
*/ |
|
static int get_file_caps(struct linux_binprm *bprm, struct file *file, |
|
bool *effective, bool *has_fcap) |
|
{ |
|
int rc = 0; |
|
struct cpu_vfs_cap_data vcaps; |
|
|
|
cap_clear(bprm->cred->cap_permitted); |
|
|
|
if (!file_caps_enabled) |
|
return 0; |
|
|
|
if (!mnt_may_suid(file->f_path.mnt)) |
|
return 0; |
|
|
|
/* |
|
* This check is redundant with mnt_may_suid() but is kept to make |
|
* explicit that capability bits are limited to s_user_ns and its |
|
* descendants. |
|
*/ |
|
if (!current_in_userns(file->f_path.mnt->mnt_sb->s_user_ns)) |
|
return 0; |
|
|
|
rc = get_vfs_caps_from_disk(file_mnt_user_ns(file), |
|
file->f_path.dentry, &vcaps); |
|
if (rc < 0) { |
|
if (rc == -EINVAL) |
|
printk(KERN_NOTICE "Invalid argument reading file caps for %s\n", |
|
bprm->filename); |
|
else if (rc == -ENODATA) |
|
rc = 0; |
|
goto out; |
|
} |
|
|
|
rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_fcap); |
|
|
|
out: |
|
if (rc) |
|
cap_clear(bprm->cred->cap_permitted); |
|
|
|
return rc; |
|
} |
|
|
|
static inline bool root_privileged(void) { return !issecure(SECURE_NOROOT); } |
|
|
|
static inline bool __is_real(kuid_t uid, struct cred *cred) |
|
{ return uid_eq(cred->uid, uid); } |
|
|
|
static inline bool __is_eff(kuid_t uid, struct cred *cred) |
|
{ return uid_eq(cred->euid, uid); } |
|
|
|
static inline bool __is_suid(kuid_t uid, struct cred *cred) |
|
{ return !__is_real(uid, cred) && __is_eff(uid, cred); } |
|
|
|
/* |
|
* handle_privileged_root - Handle case of privileged root |
|
* @bprm: The execution parameters, including the proposed creds |
|
* @has_fcap: Are any file capabilities set? |
|
* @effective: Do we have effective root privilege? |
|
* @root_uid: This namespace' root UID WRT initial USER namespace |
|
* |
|
* Handle the case where root is privileged and hasn't been neutered by |
|
* SECURE_NOROOT. If file capabilities are set, they won't be combined with |
|
* set UID root and nothing is changed. If we are root, cap_permitted is |
|
* updated. If we have become set UID root, the effective bit is set. |
|
*/ |
|
static void handle_privileged_root(struct linux_binprm *bprm, bool has_fcap, |
|
bool *effective, kuid_t root_uid) |
|
{ |
|
const struct cred *old = current_cred(); |
|
struct cred *new = bprm->cred; |
|
|
|
if (!root_privileged()) |
|
return; |
|
/* |
|
* If the legacy file capability is set, then don't set privs |
|
* for a setuid root binary run by a non-root user. Do set it |
|
* for a root user just to cause least surprise to an admin. |
|
*/ |
|
if (has_fcap && __is_suid(root_uid, new)) { |
|
warn_setuid_and_fcaps_mixed(bprm->filename); |
|
return; |
|
} |
|
/* |
|
* To support inheritance of root-permissions and suid-root |
|
* executables under compatibility mode, we override the |
|
* capability sets for the file. |
|
*/ |
|
if (__is_eff(root_uid, new) || __is_real(root_uid, new)) { |
|
/* pP' = (cap_bset & ~0) | (pI & ~0) */ |
|
new->cap_permitted = cap_combine(old->cap_bset, |
|
old->cap_inheritable); |
|
} |
|
/* |
|
* If only the real uid is 0, we do not set the effective bit. |
|
*/ |
|
if (__is_eff(root_uid, new)) |
|
*effective = true; |
|
} |
|
|
|
#define __cap_gained(field, target, source) \ |
|
!cap_issubset(target->cap_##field, source->cap_##field) |
|
#define __cap_grew(target, source, cred) \ |
|
!cap_issubset(cred->cap_##target, cred->cap_##source) |
|
#define __cap_full(field, cred) \ |
|
cap_issubset(CAP_FULL_SET, cred->cap_##field) |
|
|
|
static inline bool __is_setuid(struct cred *new, const struct cred *old) |
|
{ return !uid_eq(new->euid, old->uid); } |
|
|
|
static inline bool __is_setgid(struct cred *new, const struct cred *old) |
|
{ return !gid_eq(new->egid, old->gid); } |
|
|
|
/* |
|
* 1) Audit candidate if current->cap_effective is set |
|
* |
|
* We do not bother to audit if 3 things are true: |
|
* 1) cap_effective has all caps |
|
* 2) we became root *OR* are were already root |
|
* 3) root is supposed to have all caps (SECURE_NOROOT) |
|
* Since this is just a normal root execing a process. |
|
* |
|
* Number 1 above might fail if you don't have a full bset, but I think |
|
* that is interesting information to audit. |
|
* |
|
* A number of other conditions require logging: |
|
* 2) something prevented setuid root getting all caps |
|
* 3) non-setuid root gets fcaps |
|
* 4) non-setuid root gets ambient |
|
*/ |
|
static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old, |
|
kuid_t root, bool has_fcap) |
|
{ |
|
bool ret = false; |
|
|
|
if ((__cap_grew(effective, ambient, new) && |
|
!(__cap_full(effective, new) && |
|
(__is_eff(root, new) || __is_real(root, new)) && |
|
root_privileged())) || |
|
(root_privileged() && |
|
__is_suid(root, new) && |
|
!__cap_full(effective, new)) || |
|
(!__is_setuid(new, old) && |
|
((has_fcap && |
|
__cap_gained(permitted, new, old)) || |
|
__cap_gained(ambient, new, old)))) |
|
|
|
ret = true; |
|
|
|
return ret; |
|
} |
|
|
|
/** |
|
* cap_bprm_creds_from_file - Set up the proposed credentials for execve(). |
|
* @bprm: The execution parameters, including the proposed creds |
|
* @file: The file to pull the credentials from |
|
* |
|
* Set up the proposed credentials for a new execution context being |
|
* constructed by execve(). The proposed creds in @bprm->cred is altered, |
|
* which won't take effect immediately. |
|
* |
|
* Return: 0 if successful, -ve on error. |
|
*/ |
|
int cap_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file) |
|
{ |
|
/* Process setpcap binaries and capabilities for uid 0 */ |
|
const struct cred *old = current_cred(); |
|
struct cred *new = bprm->cred; |
|
bool effective = false, has_fcap = false, is_setid; |
|
int ret; |
|
kuid_t root_uid; |
|
|
|
if (WARN_ON(!cap_ambient_invariant_ok(old))) |
|
return -EPERM; |
|
|
|
ret = get_file_caps(bprm, file, &effective, &has_fcap); |
|
if (ret < 0) |
|
return ret; |
|
|
|
root_uid = make_kuid(new->user_ns, 0); |
|
|
|
handle_privileged_root(bprm, has_fcap, &effective, root_uid); |
|
|
|
/* if we have fs caps, clear dangerous personality flags */ |
|
if (__cap_gained(permitted, new, old)) |
|
bprm->per_clear |= PER_CLEAR_ON_SETID; |
|
|
|
/* Don't let someone trace a set[ug]id/setpcap binary with the revised |
|
* credentials unless they have the appropriate permit. |
|
* |
|
* In addition, if NO_NEW_PRIVS, then ensure we get no new privs. |
|
*/ |
|
is_setid = __is_setuid(new, old) || __is_setgid(new, old); |
|
|
|
if ((is_setid || __cap_gained(permitted, new, old)) && |
|
((bprm->unsafe & ~LSM_UNSAFE_PTRACE) || |
|
!ptracer_capable(current, new->user_ns))) { |
|
/* downgrade; they get no more than they had, and maybe less */ |
|
if (!ns_capable(new->user_ns, CAP_SETUID) || |
|
(bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) { |
|
new->euid = new->uid; |
|
new->egid = new->gid; |
|
} |
|
new->cap_permitted = cap_intersect(new->cap_permitted, |
|
old->cap_permitted); |
|
} |
|
|
|
new->suid = new->fsuid = new->euid; |
|
new->sgid = new->fsgid = new->egid; |
|
|
|
/* File caps or setid cancels ambient. */ |
|
if (has_fcap || is_setid) |
|
cap_clear(new->cap_ambient); |
|
|
|
/* |
|
* Now that we've computed pA', update pP' to give: |
|
* pP' = (X & fP) | (pI & fI) | pA' |
|
*/ |
|
new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient); |
|
|
|
/* |
|
* Set pE' = (fE ? pP' : pA'). Because pA' is zero if fE is set, |
|
* this is the same as pE' = (fE ? pP' : 0) | pA'. |
|
*/ |
|
if (effective) |
|
new->cap_effective = new->cap_permitted; |
|
else |
|
new->cap_effective = new->cap_ambient; |
|
|
|
if (WARN_ON(!cap_ambient_invariant_ok(new))) |
|
return -EPERM; |
|
|
|
if (nonroot_raised_pE(new, old, root_uid, has_fcap)) { |
|
ret = audit_log_bprm_fcaps(bprm, new, old); |
|
if (ret < 0) |
|
return ret; |
|
} |
|
|
|
new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); |
|
|
|
if (WARN_ON(!cap_ambient_invariant_ok(new))) |
|
return -EPERM; |
|
|
|
/* Check for privilege-elevated exec. */ |
|
if (is_setid || |
|
(!__is_real(root_uid, new) && |
|
(effective || |
|
__cap_grew(permitted, ambient, new)))) |
|
bprm->secureexec = 1; |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* cap_inode_setxattr - Determine whether an xattr may be altered |
|
* @dentry: The inode/dentry being altered |
|
* @name: The name of the xattr to be changed |
|
* @value: The value that the xattr will be changed to |
|
* @size: The size of value |
|
* @flags: The replacement flag |
|
* |
|
* Determine whether an xattr may be altered or set on an inode, returning 0 if |
|
* permission is granted, -ve if denied. |
|
* |
|
* This is used to make sure security xattrs don't get updated or set by those |
|
* who aren't privileged to do so. |
|
*/ |
|
int cap_inode_setxattr(struct dentry *dentry, const char *name, |
|
const void *value, size_t size, int flags) |
|
{ |
|
struct user_namespace *user_ns = dentry->d_sb->s_user_ns; |
|
|
|
/* Ignore non-security xattrs */ |
|
if (strncmp(name, XATTR_SECURITY_PREFIX, |
|
XATTR_SECURITY_PREFIX_LEN) != 0) |
|
return 0; |
|
|
|
/* |
|
* For XATTR_NAME_CAPS the check will be done in |
|
* cap_convert_nscap(), called by setxattr() |
|
*/ |
|
if (strcmp(name, XATTR_NAME_CAPS) == 0) |
|
return 0; |
|
|
|
if (!ns_capable(user_ns, CAP_SYS_ADMIN)) |
|
return -EPERM; |
|
return 0; |
|
} |
|
|
|
/** |
|
* cap_inode_removexattr - Determine whether an xattr may be removed |
|
* |
|
* @mnt_userns: User namespace of the mount the inode was found from |
|
* @dentry: The inode/dentry being altered |
|
* @name: The name of the xattr to be changed |
|
* |
|
* Determine whether an xattr may be removed from an inode, returning 0 if |
|
* permission is granted, -ve if denied. |
|
* |
|
* If the inode has been found through an idmapped mount the user namespace of |
|
* the vfsmount must be passed through @mnt_userns. This function will then |
|
* take care to map the inode according to @mnt_userns before checking |
|
* permissions. On non-idmapped mounts or if permission checking is to be |
|
* performed on the raw inode simply passs init_user_ns. |
|
* |
|
* This is used to make sure security xattrs don't get removed by those who |
|
* aren't privileged to remove them. |
|
*/ |
|
int cap_inode_removexattr(struct user_namespace *mnt_userns, |
|
struct dentry *dentry, const char *name) |
|
{ |
|
struct user_namespace *user_ns = dentry->d_sb->s_user_ns; |
|
|
|
/* Ignore non-security xattrs */ |
|
if (strncmp(name, XATTR_SECURITY_PREFIX, |
|
XATTR_SECURITY_PREFIX_LEN) != 0) |
|
return 0; |
|
|
|
if (strcmp(name, XATTR_NAME_CAPS) == 0) { |
|
/* security.capability gets namespaced */ |
|
struct inode *inode = d_backing_inode(dentry); |
|
if (!inode) |
|
return -EINVAL; |
|
if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP)) |
|
return -EPERM; |
|
return 0; |
|
} |
|
|
|
if (!ns_capable(user_ns, CAP_SYS_ADMIN)) |
|
return -EPERM; |
|
return 0; |
|
} |
|
|
|
/* |
|
* cap_emulate_setxuid() fixes the effective / permitted capabilities of |
|
* a process after a call to setuid, setreuid, or setresuid. |
|
* |
|
* 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of |
|
* {r,e,s}uid != 0, the permitted and effective capabilities are |
|
* cleared. |
|
* |
|
* 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective |
|
* capabilities of the process are cleared. |
|
* |
|
* 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective |
|
* capabilities are set to the permitted capabilities. |
|
* |
|
* fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should |
|
* never happen. |
|
* |
|
* -astor |
|
* |
|
* cevans - New behaviour, Oct '99 |
|
* A process may, via prctl(), elect to keep its capabilities when it |
|
* calls setuid() and switches away from uid==0. Both permitted and |
|
* effective sets will be retained. |
|
* Without this change, it was impossible for a daemon to drop only some |
|
* of its privilege. The call to setuid(!=0) would drop all privileges! |
|
* Keeping uid 0 is not an option because uid 0 owns too many vital |
|
* files.. |
|
* Thanks to Olaf Kirch and Peter Benie for spotting this. |
|
*/ |
|
static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old) |
|
{ |
|
kuid_t root_uid = make_kuid(old->user_ns, 0); |
|
|
|
if ((uid_eq(old->uid, root_uid) || |
|
uid_eq(old->euid, root_uid) || |
|
uid_eq(old->suid, root_uid)) && |
|
(!uid_eq(new->uid, root_uid) && |
|
!uid_eq(new->euid, root_uid) && |
|
!uid_eq(new->suid, root_uid))) { |
|
if (!issecure(SECURE_KEEP_CAPS)) { |
|
cap_clear(new->cap_permitted); |
|
cap_clear(new->cap_effective); |
|
} |
|
|
|
/* |
|
* Pre-ambient programs expect setresuid to nonroot followed |
|
* by exec to drop capabilities. We should make sure that |
|
* this remains the case. |
|
*/ |
|
cap_clear(new->cap_ambient); |
|
} |
|
if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid)) |
|
cap_clear(new->cap_effective); |
|
if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid)) |
|
new->cap_effective = new->cap_permitted; |
|
} |
|
|
|
/** |
|
* cap_task_fix_setuid - Fix up the results of setuid() call |
|
* @new: The proposed credentials |
|
* @old: The current task's current credentials |
|
* @flags: Indications of what has changed |
|
* |
|
* Fix up the results of setuid() call before the credential changes are |
|
* actually applied. |
|
* |
|
* Return: 0 to grant the changes, -ve to deny them. |
|
*/ |
|
int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags) |
|
{ |
|
switch (flags) { |
|
case LSM_SETID_RE: |
|
case LSM_SETID_ID: |
|
case LSM_SETID_RES: |
|
/* juggle the capabilities to follow [RES]UID changes unless |
|
* otherwise suppressed */ |
|
if (!issecure(SECURE_NO_SETUID_FIXUP)) |
|
cap_emulate_setxuid(new, old); |
|
break; |
|
|
|
case LSM_SETID_FS: |
|
/* juggle the capabilties to follow FSUID changes, unless |
|
* otherwise suppressed |
|
* |
|
* FIXME - is fsuser used for all CAP_FS_MASK capabilities? |
|
* if not, we might be a bit too harsh here. |
|
*/ |
|
if (!issecure(SECURE_NO_SETUID_FIXUP)) { |
|
kuid_t root_uid = make_kuid(old->user_ns, 0); |
|
if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid)) |
|
new->cap_effective = |
|
cap_drop_fs_set(new->cap_effective); |
|
|
|
if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid)) |
|
new->cap_effective = |
|
cap_raise_fs_set(new->cap_effective, |
|
new->cap_permitted); |
|
} |
|
break; |
|
|
|
default: |
|
return -EINVAL; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
/* |
|
* Rationale: code calling task_setscheduler, task_setioprio, and |
|
* task_setnice, assumes that |
|
* . if capable(cap_sys_nice), then those actions should be allowed |
|
* . if not capable(cap_sys_nice), but acting on your own processes, |
|
* then those actions should be allowed |
|
* This is insufficient now since you can call code without suid, but |
|
* yet with increased caps. |
|
* So we check for increased caps on the target process. |
|
*/ |
|
static int cap_safe_nice(struct task_struct *p) |
|
{ |
|
int is_subset, ret = 0; |
|
|
|
rcu_read_lock(); |
|
is_subset = cap_issubset(__task_cred(p)->cap_permitted, |
|
current_cred()->cap_permitted); |
|
if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) |
|
ret = -EPERM; |
|
rcu_read_unlock(); |
|
|
|
return ret; |
|
} |
|
|
|
/** |
|
* cap_task_setscheduler - Detemine if scheduler policy change is permitted |
|
* @p: The task to affect |
|
* |
|
* Detemine if the requested scheduler policy change is permitted for the |
|
* specified task. |
|
* |
|
* Return: 0 if permission is granted, -ve if denied. |
|
*/ |
|
int cap_task_setscheduler(struct task_struct *p) |
|
{ |
|
return cap_safe_nice(p); |
|
} |
|
|
|
/** |
|
* cap_task_setioprio - Detemine if I/O priority change is permitted |
|
* @p: The task to affect |
|
* @ioprio: The I/O priority to set |
|
* |
|
* Detemine if the requested I/O priority change is permitted for the specified |
|
* task. |
|
* |
|
* Return: 0 if permission is granted, -ve if denied. |
|
*/ |
|
int cap_task_setioprio(struct task_struct *p, int ioprio) |
|
{ |
|
return cap_safe_nice(p); |
|
} |
|
|
|
/** |
|
* cap_task_setnice - Detemine if task priority change is permitted |
|
* @p: The task to affect |
|
* @nice: The nice value to set |
|
* |
|
* Detemine if the requested task priority change is permitted for the |
|
* specified task. |
|
* |
|
* Return: 0 if permission is granted, -ve if denied. |
|
*/ |
|
int cap_task_setnice(struct task_struct *p, int nice) |
|
{ |
|
return cap_safe_nice(p); |
|
} |
|
|
|
/* |
|
* Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from |
|
* the current task's bounding set. Returns 0 on success, -ve on error. |
|
*/ |
|
static int cap_prctl_drop(unsigned long cap) |
|
{ |
|
struct cred *new; |
|
|
|
if (!ns_capable(current_user_ns(), CAP_SETPCAP)) |
|
return -EPERM; |
|
if (!cap_valid(cap)) |
|
return -EINVAL; |
|
|
|
new = prepare_creds(); |
|
if (!new) |
|
return -ENOMEM; |
|
cap_lower(new->cap_bset, cap); |
|
return commit_creds(new); |
|
} |
|
|
|
/** |
|
* cap_task_prctl - Implement process control functions for this security module |
|
* @option: The process control function requested |
|
* @arg2: The argument data for this function |
|
* @arg3: The argument data for this function |
|
* @arg4: The argument data for this function |
|
* @arg5: The argument data for this function |
|
* |
|
* Allow process control functions (sys_prctl()) to alter capabilities; may |
|
* also deny access to other functions not otherwise implemented here. |
|
* |
|
* Return: 0 or +ve on success, -ENOSYS if this function is not implemented |
|
* here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM |
|
* modules will consider performing the function. |
|
*/ |
|
int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, |
|
unsigned long arg4, unsigned long arg5) |
|
{ |
|
const struct cred *old = current_cred(); |
|
struct cred *new; |
|
|
|
switch (option) { |
|
case PR_CAPBSET_READ: |
|
if (!cap_valid(arg2)) |
|
return -EINVAL; |
|
return !!cap_raised(old->cap_bset, arg2); |
|
|
|
case PR_CAPBSET_DROP: |
|
return cap_prctl_drop(arg2); |
|
|
|
/* |
|
* The next four prctl's remain to assist with transitioning a |
|
* system from legacy UID=0 based privilege (when filesystem |
|
* capabilities are not in use) to a system using filesystem |
|
* capabilities only - as the POSIX.1e draft intended. |
|
* |
|
* Note: |
|
* |
|
* PR_SET_SECUREBITS = |
|
* issecure_mask(SECURE_KEEP_CAPS_LOCKED) |
|
* | issecure_mask(SECURE_NOROOT) |
|
* | issecure_mask(SECURE_NOROOT_LOCKED) |
|
* | issecure_mask(SECURE_NO_SETUID_FIXUP) |
|
* | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED) |
|
* |
|
* will ensure that the current process and all of its |
|
* children will be locked into a pure |
|
* capability-based-privilege environment. |
|
*/ |
|
case PR_SET_SECUREBITS: |
|
if ((((old->securebits & SECURE_ALL_LOCKS) >> 1) |
|
& (old->securebits ^ arg2)) /*[1]*/ |
|
|| ((old->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/ |
|
|| (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/ |
|
|| (cap_capable(current_cred(), |
|
current_cred()->user_ns, |
|
CAP_SETPCAP, |
|
CAP_OPT_NONE) != 0) /*[4]*/ |
|
/* |
|
* [1] no changing of bits that are locked |
|
* [2] no unlocking of locks |
|
* [3] no setting of unsupported bits |
|
* [4] doing anything requires privilege (go read about |
|
* the "sendmail capabilities bug") |
|
*/ |
|
) |
|
/* cannot change a locked bit */ |
|
return -EPERM; |
|
|
|
new = prepare_creds(); |
|
if (!new) |
|
return -ENOMEM; |
|
new->securebits = arg2; |
|
return commit_creds(new); |
|
|
|
case PR_GET_SECUREBITS: |
|
return old->securebits; |
|
|
|
case PR_GET_KEEPCAPS: |
|
return !!issecure(SECURE_KEEP_CAPS); |
|
|
|
case PR_SET_KEEPCAPS: |
|
if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */ |
|
return -EINVAL; |
|
if (issecure(SECURE_KEEP_CAPS_LOCKED)) |
|
return -EPERM; |
|
|
|
new = prepare_creds(); |
|
if (!new) |
|
return -ENOMEM; |
|
if (arg2) |
|
new->securebits |= issecure_mask(SECURE_KEEP_CAPS); |
|
else |
|
new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); |
|
return commit_creds(new); |
|
|
|
case PR_CAP_AMBIENT: |
|
if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) { |
|
if (arg3 | arg4 | arg5) |
|
return -EINVAL; |
|
|
|
new = prepare_creds(); |
|
if (!new) |
|
return -ENOMEM; |
|
cap_clear(new->cap_ambient); |
|
return commit_creds(new); |
|
} |
|
|
|
if (((!cap_valid(arg3)) | arg4 | arg5)) |
|
return -EINVAL; |
|
|
|
if (arg2 == PR_CAP_AMBIENT_IS_SET) { |
|
return !!cap_raised(current_cred()->cap_ambient, arg3); |
|
} else if (arg2 != PR_CAP_AMBIENT_RAISE && |
|
arg2 != PR_CAP_AMBIENT_LOWER) { |
|
return -EINVAL; |
|
} else { |
|
if (arg2 == PR_CAP_AMBIENT_RAISE && |
|
(!cap_raised(current_cred()->cap_permitted, arg3) || |
|
!cap_raised(current_cred()->cap_inheritable, |
|
arg3) || |
|
issecure(SECURE_NO_CAP_AMBIENT_RAISE))) |
|
return -EPERM; |
|
|
|
new = prepare_creds(); |
|
if (!new) |
|
return -ENOMEM; |
|
if (arg2 == PR_CAP_AMBIENT_RAISE) |
|
cap_raise(new->cap_ambient, arg3); |
|
else |
|
cap_lower(new->cap_ambient, arg3); |
|
return commit_creds(new); |
|
} |
|
|
|
default: |
|
/* No functionality available - continue with default */ |
|
return -ENOSYS; |
|
} |
|
} |
|
|
|
/** |
|
* cap_vm_enough_memory - Determine whether a new virtual mapping is permitted |
|
* @mm: The VM space in which the new mapping is to be made |
|
* @pages: The size of the mapping |
|
* |
|
* Determine whether the allocation of a new virtual mapping by the current |
|
* task is permitted. |
|
* |
|
* Return: 1 if permission is granted, 0 if not. |
|
*/ |
|
int cap_vm_enough_memory(struct mm_struct *mm, long pages) |
|
{ |
|
int cap_sys_admin = 0; |
|
|
|
if (cap_capable(current_cred(), &init_user_ns, |
|
CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) == 0) |
|
cap_sys_admin = 1; |
|
|
|
return cap_sys_admin; |
|
} |
|
|
|
/** |
|
* cap_mmap_addr - check if able to map given addr |
|
* @addr: address attempting to be mapped |
|
* |
|
* If the process is attempting to map memory below dac_mmap_min_addr they need |
|
* CAP_SYS_RAWIO. The other parameters to this function are unused by the |
|
* capability security module. |
|
* |
|
* Return: 0 if this mapping should be allowed or -EPERM if not. |
|
*/ |
|
int cap_mmap_addr(unsigned long addr) |
|
{ |
|
int ret = 0; |
|
|
|
if (addr < dac_mmap_min_addr) { |
|
ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO, |
|
CAP_OPT_NONE); |
|
/* set PF_SUPERPRIV if it turns out we allow the low mmap */ |
|
if (ret == 0) |
|
current->flags |= PF_SUPERPRIV; |
|
} |
|
return ret; |
|
} |
|
|
|
int cap_mmap_file(struct file *file, unsigned long reqprot, |
|
unsigned long prot, unsigned long flags) |
|
{ |
|
return 0; |
|
} |
|
|
|
#ifdef CONFIG_SECURITY |
|
|
|
static struct security_hook_list capability_hooks[] __lsm_ro_after_init = { |
|
LSM_HOOK_INIT(capable, cap_capable), |
|
LSM_HOOK_INIT(settime, cap_settime), |
|
LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check), |
|
LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme), |
|
LSM_HOOK_INIT(capget, cap_capget), |
|
LSM_HOOK_INIT(capset, cap_capset), |
|
LSM_HOOK_INIT(bprm_creds_from_file, cap_bprm_creds_from_file), |
|
LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv), |
|
LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv), |
|
LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity), |
|
LSM_HOOK_INIT(mmap_addr, cap_mmap_addr), |
|
LSM_HOOK_INIT(mmap_file, cap_mmap_file), |
|
LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid), |
|
LSM_HOOK_INIT(task_prctl, cap_task_prctl), |
|
LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler), |
|
LSM_HOOK_INIT(task_setioprio, cap_task_setioprio), |
|
LSM_HOOK_INIT(task_setnice, cap_task_setnice), |
|
LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory), |
|
}; |
|
|
|
static int __init capability_init(void) |
|
{ |
|
security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks), |
|
"capability"); |
|
return 0; |
|
} |
|
|
|
DEFINE_LSM(capability) = { |
|
.name = "capability", |
|
.order = LSM_ORDER_FIRST, |
|
.init = capability_init, |
|
}; |
|
|
|
#endif /* CONFIG_SECURITY */
|
|
|