| /* Common capabilities, needed by capability.o. |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| */ |
| |
| #include <linux/capability.h> |
| #include <linux/audit.h> |
| #include <linux/module.h> |
| #include <linux/init.h> |
| #include <linux/kernel.h> |
| #include <linux/lsm_hooks.h> |
| #include <linux/file.h> |
| #include <linux/mm.h> |
| #include <linux/mman.h> |
| #include <linux/pagemap.h> |
| #include <linux/swap.h> |
| #include <linux/skbuff.h> |
| #include <linux/netlink.h> |
| #include <linux/ptrace.h> |
| #include <linux/xattr.h> |
| #include <linux/hugetlb.h> |
| #include <linux/mount.h> |
| #include <linux/sched.h> |
| #include <linux/prctl.h> |
| #include <linux/securebits.h> |
| #include <linux/user_namespace.h> |
| #include <linux/binfmts.h> |
| #include <linux/personality.h> |
| |
| /* |
| * If a non-root user executes a setuid-root binary in |
| * !secure(SECURE_NOROOT) mode, then we raise capabilities. |
| * However if fE is also set, then the intent is for only |
| * the file capabilities to be applied, and the setuid-root |
| * bit is left on either to change the uid (plausible) or |
| * to get full privilege on a kernel without file capabilities |
| * support. So in that case we do not raise capabilities. |
| * |
| * Warn if that happens, once per boot. |
| */ |
| static void warn_setuid_and_fcaps_mixed(const char *fname) |
| { |
| static int warned; |
| if (!warned) { |
| printk(KERN_INFO "warning: `%s' has both setuid-root and" |
| " effective capabilities. Therefore not raising all" |
| " capabilities.\n", fname); |
| warned = 1; |
| } |
| } |
| |
| /** |
| * __cap_capable - Determine whether a task has a particular effective capability |
| * @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 |
| * |
| * Determine whether the nominated task has the specified capability amongst |
| * its effective set, returning 0 if it does, -ve if it does not. |
| * |
| * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable() |
| * and has_capability() functions. That is, it has the reverse semantics: |
| * 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(const struct cred *cred, struct user_namespace *targ_ns, |
| int cap, int audit) |
| { |
| struct user_namespace *ns = targ_ns; |
| |
| /* See if cred has the capability in the target user namespace |
| * by examining the target user namespace and all of the target |
| * user namespace's parents. |
| */ |
| for (;;) { |
| /* Do we have the necessary capabilities? */ |
| if (ns == cred->user_ns) |
| return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM; |
| |
| /* |
| * If we're already at a lower level than we're looking for, |
| * we're done searching. |
| */ |
| if (ns->level <= cred->user_ns->level) |
| return -EPERM; |
| |
| /* |
| * The owner of the user namespace in the parent of the |
| * user namespace has all caps. |
| */ |
| if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid)) |
| return 0; |
| |
| /* |
| * If you have a capability in a parent user ns, then you have |
| * it over all children user namespaces as well. |
| */ |
| ns = ns->parent; |
| } |
| |
| /* We never get here */ |
| } |
| |
| int cap_capable(const struct cred *cred, struct user_namespace *targ_ns, |
| int cap, int audit) |
| { |
| return __cap_capable(cred, targ_ns, cap, audit); |
| } |
| /** |
| * cap_settime - Determine whether the current process may set the system clock |
| * @ts: The time to set |
| * @tz: The timezone to set |
| * |
| * Determine whether the current process may set the system clock and timezone |
| * information, returning 0 if permission granted, -ve if denied. |
| */ |
| int cap_settime(const struct timespec64 *ts, const struct timezone *tz) |
| { |
| if (!capable(CAP_SYS_TIME)) |
| return -EPERM; |
| return 0; |
| } |
| |
| /** |
| * cap_ptrace_access_check - Determine whether the current process may access |
| * another |
| * @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; |
| const kernel_cap_t *caller_caps; |
| |
| rcu_read_lock(); |
| cred = current_cred(); |
| child_cred = __task_cred(child); |
| if (mode & PTRACE_MODE_FSCREDS) |
| caller_caps = &cred->cap_effective; |
| else |
| caller_caps = &cred->cap_permitted; |
| if (cred->user_ns == child_cred->user_ns && |
| cap_issubset(child_cred->cap_permitted, *caller_caps)) |
| goto out; |
| if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE)) |
| goto out; |
| ret = -EPERM; |
| out: |
| rcu_read_unlock(); |
| return ret; |
| } |
| |
| /** |
| * 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(); |
| cred = __task_cred(parent); |
| child_cred = current_cred(); |
| if (cred->user_ns == child_cred->user_ns && |
| cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) |
| goto out; |
| if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE)) |
| goto out; |
| ret = -EPERM; |
| out: |
| rcu_read_unlock(); |
| return ret; |
| } |
| |
| /** |
| * cap_capget - Retrieve a task's capability sets |
| * @target: The task from which to retrieve the capability sets |
| * @effective: The place to record the effective set |
| * @inheritable: The place to record the inheritable set |
| * @permitted: The place to record the permitted set |
| * |
| * This function retrieves the capabilities of the nominated task and returns |
| * them to the caller. |
| */ |
| int cap_capget(struct task_struct *target, kernel_cap_t *effective, |
| kernel_cap_t *inheritable, kernel_cap_t *permitted) |
| { |
| const struct cred *cred; |
| |
| /* Derived from kernel/capability.c:sys_capget. */ |
| rcu_read_lock(); |
| cred = __task_cred(target); |
| *effective = cred->cap_effective; |
| *inheritable = cred->cap_inheritable; |
| *permitted = cred->cap_permitted; |
| rcu_read_unlock(); |
| return 0; |
| } |
| |
| /* |
| * Determine whether the inheritable capabilities are limited to the old |
| * permitted set. Returns 1 if they are limited, 0 if they are not. |
| */ |
| 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_cred(), current_cred()->user_ns, |
| CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0) |
| return 0; |
| return 1; |
| } |
| |
| /** |
| * cap_capset - Validate and apply proposed changes to current's capabilities |
| * @new: The proposed new credentials; alterations should be made here |
| * @old: The current task's current credentials |
| * @effective: A pointer to the proposed new effective capabilities set |
| * @inheritable: A pointer to the proposed new inheritable capabilities set |
| * @permitted: A pointer to the proposed new permitted capabilities set |
| * |
| * This function validates and applies a proposed mass change to the current |
| * process's capability sets. The changes are made to the proposed new |
| * credentials, and assuming no error, will be committed by the caller of LSM. |
| */ |
| int cap_capset(struct cred *new, |
| const struct cred *old, |
| const kernel_cap_t *effective, |
| const kernel_cap_t *inheritable, |
| const kernel_cap_t *permitted) |
| { |
| if (cap_inh_is_capped() && |
| !cap_issubset(*inheritable, |
| cap_combine(old->cap_inheritable, |
| old->cap_permitted))) |
| /* incapable of using this inheritable set */ |
| return -EPERM; |
| |
| if (!cap_issubset(*inheritable, |
| cap_combine(old->cap_inheritable, |
| old->cap_bset))) |
| /* no new pI capabilities outside bounding set */ |
| return -EPERM; |
| |
| /* verify restrictions on target's new Permitted set */ |
| if (!cap_issubset(*permitted, old->cap_permitted)) |
| return -EPERM; |
| |
| /* verify the _new_Effective_ is a subset of the _new_Permitted_ */ |
| if (!cap_issubset(*effective, *permitted)) |
| return -EPERM; |
| |
| new->cap_effective = *effective; |
| new->cap_inheritable = *inheritable; |
| new->cap_permitted = *permitted; |
| |
| /* |
| * Mask off ambient bits that are no longer both permitted and |
| * inheritable. |
| */ |
| new->cap_ambient = cap_intersect(new->cap_ambient, |
| cap_intersect(*permitted, |
| *inheritable)); |
| if (WARN_ON(!cap_ambient_invariant_ok(new))) |
| return -EINVAL; |
| return 0; |
| } |
| |
| /** |
| * cap_inode_need_killpriv - Determine if inode change affects privileges |
| * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV |
| * |
| * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV |
| * affects the security markings on that inode, and if it is, should |
| * inode_killpriv() be invoked or the change rejected. |
| * |
| * Returns 1 if security.capability has a value, meaning inode_killpriv() |
| * is required, 0 otherwise, meaning inode_killpriv() is not required. |
| */ |
| int cap_inode_need_killpriv(struct dentry *dentry) |
| { |
| struct inode *inode = d_backing_inode(dentry); |
| int error; |
| |
| error = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0); |
| return error > 0; |
| } |
| |
| /** |
| * cap_inode_killpriv - Erase the security markings on an inode |
| * @dentry: The inode/dentry to alter |
| * |
| * Erase the privilege-enhancing security markings on an inode. |
| * |
| * Returns 0 if successful, -ve on error. |
| */ |
| int cap_inode_killpriv(struct dentry *dentry) |
| { |
| int error; |
| |
| error = __vfs_removexattr(dentry, XATTR_NAME_CAPS); |
| if (error == -EOPNOTSUPP) |
| error = 0; |
| return error; |
| } |
| |
| static bool rootid_owns_currentns(kuid_t kroot) |
| { |
| struct user_namespace *ns; |
| |
| if (!uid_valid(kroot)) |
| return false; |
| |
| for (ns = current_user_ns(); ; ns = ns->parent) { |
| if (from_kuid(ns, kroot) == 0) |
| return true; |
| if (ns == &init_user_ns) |
| break; |
| } |
| |
| return false; |
| } |
| |
| static __u32 sansflags(__u32 m) |
| { |
| return m & ~VFS_CAP_FLAGS_EFFECTIVE; |
| } |
| |
| static bool is_v2header(size_t size, const struct vfs_cap_data *cap) |
| { |
| if (size != XATTR_CAPS_SZ_2) |
| return false; |
| return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_2; |
| } |
| |
| static bool is_v3header(size_t size, const struct vfs_cap_data *cap) |
| { |
| if (size != XATTR_CAPS_SZ_3) |
| return false; |
| return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_3; |
| } |
| |
| /* |
| * getsecurity: We are called for security.* before any attempt to read the |
| * xattr from the inode itself. |
| * |
| * This gives us a chance to read the on-disk value and convert it. If we |
| * return -EOPNOTSUPP, then vfs_getxattr() will call the i_op handler. |
| * |
| * Note we are not called by vfs_getxattr_alloc(), but that is only called |
| * by the integrity subsystem, which really wants the unconverted values - |
| * so that's good. |
| */ |
| int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer, |
| bool alloc) |
| { |
| int size, ret; |
| kuid_t kroot; |
| uid_t root, mappedroot; |
| char *tmpbuf = NULL; |
| struct vfs_cap_data *cap; |
| struct vfs_ns_cap_data *nscap; |
| struct dentry *dentry; |
| struct user_namespace *fs_ns; |
| |
| if (strcmp(name, "capability") != 0) |
| return -EOPNOTSUPP; |
| |
| dentry = d_find_any_alias(inode); |
| if (!dentry) |
| return -EINVAL; |
| |
| size = sizeof(struct vfs_ns_cap_data); |
| ret = (int) vfs_getxattr_alloc(dentry, XATTR_NAME_CAPS, |
| &tmpbuf, size, GFP_NOFS); |
| dput(dentry); |
| |
| if (ret < 0) |
| return ret; |
| |
| fs_ns = inode->i_sb->s_user_ns; |
| cap = (struct vfs_cap_data *) tmpbuf; |
| if (is_v2header((size_t) ret, cap)) { |
| /* If this is sizeof(vfs_cap_data) then we're ok with the |
| * on-disk value, so return that. */ |
| if (alloc) |
| *buffer = tmpbuf; |
| else |
| kfree(tmpbuf); |
| return ret; |
| } else if (!is_v3header((size_t) ret, cap)) { |
| kfree(tmpbuf); |
| return -EINVAL; |
| } |
| |
| nscap = (struct vfs_ns_cap_data *) tmpbuf; |
| root = le32_to_cpu(nscap->rootid); |
| kroot = make_kuid(fs_ns, root); |
| |
| /* 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) { |
| if (alloc) { |
| *buffer = tmpbuf; |
| nscap->rootid = cpu_to_le32(mappedroot); |
| } else |
| kfree(tmpbuf); |
| return size; |
| } |
| |
| if (!rootid_owns_currentns(kroot)) { |
| kfree(tmpbuf); |
| return -EOPNOTSUPP; |
| } |
| |
| /* This comes from a parent namespace. Return as a v2 capability */ |
| size = sizeof(struct vfs_cap_data); |
| if (alloc) { |
| *buffer = kmalloc(size, GFP_ATOMIC); |
| if (*buffer) { |
| struct vfs_cap_data *cap = *buffer; |
| __le32 nsmagic, magic; |
| 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 { |
| size = -ENOMEM; |
| } |
| } |
| kfree(tmpbuf); |
| return size; |
| } |
| |
| static kuid_t rootid_from_xattr(const void *value, size_t size, |
| struct user_namespace *task_ns) |
| { |
| const struct vfs_ns_cap_data *nscap = value; |
| uid_t rootid = 0; |
| |
| if (size == XATTR_CAPS_SZ_3) |
| rootid = le32_to_cpu(nscap->rootid); |
| |
| return make_kuid(task_ns, rootid); |
| } |
| |
| static bool validheader(size_t size, const struct vfs_cap_data *cap) |
| { |
| return is_v2header(size, cap) || is_v3header(size, cap); |
| } |
| |
| /* |
| * 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 all is ok, we return the new size, on error return < 0. |
| */ |
| int cap_convert_nscap(struct dentry *dentry, 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(inode, CAP_SETFCAP)) |
| return -EPERM; |
| if (size == XATTR_CAPS_SZ_2) |
| 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); |
| 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); |
| |
| kvfree(*ivalue); |
| *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_cap) |
| { |
| 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_cap = 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; |
| } |
| |
| /* |
| * Extract the on-exec-apply capability sets for an executable file. |
| */ |
| int get_vfs_caps_from_disk(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. |
| */ |
| 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; |
| |
| 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, bool *effective, bool *has_cap) |
| { |
| 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(bprm->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(bprm->file->f_path.mnt->mnt_sb->s_user_ns)) |
| return 0; |
| |
| rc = get_vfs_caps_from_disk(bprm->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_cap); |
| if (rc == -EINVAL) |
| printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n", |
| __func__, rc, bprm->filename); |
| |
| out: |
| if (rc) |
| cap_clear(bprm->cred->cap_permitted); |
| |
| return rc; |
| } |
| |
| /** |
| * cap_bprm_set_creds - Set up the proposed credentials for execve(). |
| * @bprm: The execution parameters, including the proposed creds |
| * |
| * 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. Returns 0 if successful, -ve on error. |
| */ |
| int cap_bprm_set_creds(struct linux_binprm *bprm) |
| { |
| const struct cred *old = current_cred(); |
| struct cred *new = bprm->cred; |
| bool effective, has_cap = false, is_setid; |
| int ret; |
| kuid_t root_uid; |
| |
| if (WARN_ON(!cap_ambient_invariant_ok(old))) |
| return -EPERM; |
| |
| effective = false; |
| ret = get_file_caps(bprm, &effective, &has_cap); |
| if (ret < 0) |
| return ret; |
| |
| root_uid = make_kuid(new->user_ns, 0); |
| |
| if (!issecure(SECURE_NOROOT)) { |
| /* |
| * 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_cap && !uid_eq(new->uid, root_uid) && uid_eq(new->euid, root_uid)) { |
| warn_setuid_and_fcaps_mixed(bprm->filename); |
| goto skip; |
| } |
| /* |
| * To support inheritance of root-permissions and suid-root |
| * executables under compatibility mode, we override the |
| * capability sets for the file. |
| * |
| * If only the real uid is 0, we do not set the effective bit. |
| */ |
| if (uid_eq(new->euid, root_uid) || uid_eq(new->uid, root_uid)) { |
| /* pP' = (cap_bset & ~0) | (pI & ~0) */ |
| new->cap_permitted = cap_combine(old->cap_bset, |
| old->cap_inheritable); |
| } |
| if (uid_eq(new->euid, root_uid)) |
| effective = true; |
| } |
| skip: |
| |
| /* if we have fs caps, clear dangerous personality flags */ |
| if (!cap_issubset(new->cap_permitted, old->cap_permitted)) |
| 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 = !uid_eq(new->euid, old->uid) || !gid_eq(new->egid, old->gid); |
| |
| if ((is_setid || |
| !cap_issubset(new->cap_permitted, old->cap_permitted)) && |
| ((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_cap || 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; |
| |
| /* |
| * 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 are 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. |
| */ |
| if (!cap_issubset(new->cap_effective, new->cap_ambient)) { |
| if (!cap_issubset(CAP_FULL_SET, new->cap_effective) || |
| !uid_eq(new->euid, root_uid) || !uid_eq(new->uid, root_uid) || |
| issecure(SECURE_NOROOT)) { |
| 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. */ |
| bprm->cap_elevated = 0; |
| if (is_setid) { |
| bprm->cap_elevated = 1; |
| } else if (!uid_eq(new->uid, root_uid)) { |
| if (effective || |
| !cap_issubset(new->cap_permitted, new->cap_ambient)) |
| bprm->cap_elevated = 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) |
| { |
| /* Ignore non-security xattrs */ |
| if (strncmp(name, XATTR_SECURITY_PREFIX, |
| sizeof(XATTR_SECURITY_PREFIX) - 1) != 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 (!capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| return 0; |
| } |
| |
| /** |
| * cap_inode_removexattr - Determine whether an xattr may be removed |
| * @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. |
| * |
| * 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 dentry *dentry, const char *name) |
| { |
| /* Ignore non-security xattrs */ |
| if (strncmp(name, XATTR_SECURITY_PREFIX, |
| sizeof(XATTR_SECURITY_PREFIX) - 1) != 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(inode, CAP_SETFCAP)) |
| return -EPERM; |
| return 0; |
| } |
| |
| if (!capable(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, returning 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, returning 0 if permission is granted, -ve if denied. |
| */ |
| int cap_task_setscheduler(struct task_struct *p) |
| { |
| return cap_safe_nice(p); |
| } |
| |
| /** |
| * cap_task_ioprio - 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, returning 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_ioprio - 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, returning 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, @arg3, @arg4, @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. |
| * |
| * Returns 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, |
| SECURITY_CAP_AUDIT) != 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, returning 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, |
| SECURITY_CAP_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. Returns 0 if this mapping should be allowed |
| * -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, |
| SECURITY_CAP_AUDIT); |
| /* 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 |
| |
| 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_set_creds, cap_bprm_set_creds), |
| 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), |
| }; |
| |
| void __init capability_add_hooks(void) |
| { |
| security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks), |
| "capability"); |
| } |
| |
| #endif /* CONFIG_SECURITY */ |