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Commit e984a6dc authored by Chris Wright's avatar Chris Wright Committed by Linus Torvalds
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[PATCH] root_plug fixup 

 From: bert hubert <ahu@ds9a.nl>

 LSM: To recap, this patch allows root_plug to work again. It needs functions
 that used to reside in capability.c but linking in capability.c, disabled
 root_plug from loading, as a security module is already present then. This
 patch splits out the functions root_plug needs from capability.c.
parent 9506f564
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Showing with 356 additions and 331 deletions
security/Makefile
View file @ e984a6dc
......@@ -6,7 +6,7 @@ subdir-$(CONFIG_SECURITY_SELINUX) += selinux
# if we don't select a security model, use the default capabilities
ifneq ($(CONFIG_SECURITY),y)
obj-y += capability.o
obj-y += commoncap.o capability.o
endif
# Object file lists
......@@ -15,5 +15,5 @@ obj-$(CONFIG_SECURITY) += security.o dummy.o
ifeq ($(CONFIG_SECURITY_SELINUX),y)
obj-$(CONFIG_SECURITY_SELINUX) += selinux/built-in.o
endif
obj-$(CONFIG_SECURITY_CAPABILITIES) += capability.o
obj-$(CONFIG_SECURITY_ROOTPLUG) += root_plug.o
obj-$(CONFIG_SECURITY_CAPABILITIES) += commoncap.o capability.o
obj-$(CONFIG_SECURITY_ROOTPLUG) += commoncap.o root_plug.o
security/capability.c
View file @ e984a6dc
......@@ -23,334 +23,6 @@
#include <linux/netlink.h>
#include <linux/ptrace.h>
int cap_capable (struct task_struct *tsk, int cap)
{
/* Derived from include/linux/sched.h:capable. */
if (cap_raised (tsk->cap_effective, cap))
return 0;
else
return -EPERM;
}
int cap_ptrace (struct task_struct *parent, struct task_struct *child)
{
/* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
if (!cap_issubset (child->cap_permitted, current->cap_permitted) &&
!capable (CAP_SYS_PTRACE))
return -EPERM;
else
return 0;
}
int cap_capget (struct task_struct *target, kernel_cap_t *effective,
kernel_cap_t *inheritable, kernel_cap_t *permitted)
{
/* Derived from kernel/capability.c:sys_capget. */
*effective = cap_t (target->cap_effective);
*inheritable = cap_t (target->cap_inheritable);
*permitted = cap_t (target->cap_permitted);
return 0;
}
int cap_capset_check (struct task_struct *target, kernel_cap_t *effective,
kernel_cap_t *inheritable, kernel_cap_t *permitted)
{
/* Derived from kernel/capability.c:sys_capset. */
/* verify restrictions on target's new Inheritable set */
if (!cap_issubset (*inheritable,
cap_combine (target->cap_inheritable,
current->cap_permitted))) {
return -EPERM;
}
/* verify restrictions on target's new Permitted set */
if (!cap_issubset (*permitted,
cap_combine (target->cap_permitted,
current->cap_permitted))) {
return -EPERM;
}
/* verify the _new_Effective_ is a subset of the _new_Permitted_ */
if (!cap_issubset (*effective, *permitted)) {
return -EPERM;
}
return 0;
}
void cap_capset_set (struct task_struct *target, kernel_cap_t *effective,
kernel_cap_t *inheritable, kernel_cap_t *permitted)
{
target->cap_effective = *effective;
target->cap_inheritable = *inheritable;
target->cap_permitted = *permitted;
}
int cap_bprm_set_security (struct linux_binprm *bprm)
{
/* Copied from fs/exec.c:prepare_binprm. */
/* We don't have VFS support for capabilities yet */
cap_clear (bprm->cap_inheritable);
cap_clear (bprm->cap_permitted);
cap_clear (bprm->cap_effective);
/* To support inheritance of root-permissions and suid-root
* executables under compatibility mode, we raise all three
* capability sets for the file.
*
* If only the real uid is 0, we only raise the inheritable
* and permitted sets of the executable file.
*/
if (!issecure (SECURE_NOROOT)) {
if (bprm->e_uid == 0 || current->uid == 0) {
cap_set_full (bprm->cap_inheritable);
cap_set_full (bprm->cap_permitted);
}
if (bprm->e_uid == 0)
cap_set_full (bprm->cap_effective);
}
return 0;
}
/* Copied from fs/exec.c */
static inline int must_not_trace_exec (struct task_struct *p)
{
return (p->ptrace & PT_PTRACED) && !(p->ptrace & PT_PTRACE_CAP);
}
void cap_bprm_compute_creds (struct linux_binprm *bprm)
{
/* Derived from fs/exec.c:compute_creds. */
kernel_cap_t new_permitted, working;
new_permitted = cap_intersect (bprm->cap_permitted, cap_bset);
working = cap_intersect (bprm->cap_inheritable,
current->cap_inheritable);
new_permitted = cap_combine (new_permitted, working);
task_lock(current);
if (!cap_issubset (new_permitted, current->cap_permitted)) {
current->mm->dumpable = 0;
if (must_not_trace_exec (current)
|| atomic_read (&current->fs->count) > 1
|| atomic_read (&current->files->count) > 1
|| atomic_read (&current->sighand->count) > 1) {
if (!capable (CAP_SETPCAP)) {
new_permitted = cap_intersect (new_permitted,
current->
cap_permitted);
}
}
}
/* For init, we want to retain the capabilities set
* in the init_task struct. Thus we skip the usual
* capability rules */
if (current->pid != 1) {
current->cap_permitted = new_permitted;
current->cap_effective =
cap_intersect (new_permitted, bprm->cap_effective);
}
/* AUD: Audit candidate if current->cap_effective is set */
task_unlock(current);
current->keep_capabilities = 0;
}
int cap_bprm_secureexec (struct linux_binprm *bprm)
{
/* If/when this module is enhanced to incorporate capability
bits on files, the test below should be extended to also perform a
test between the old and new capability sets. For now,
it simply preserves the legacy decision algorithm used by
the old userland. */
return (current->euid != current->uid ||
current->egid != current->gid);
}
/* moved from kernel/sys.c. */
/*
* 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 (int old_ruid, int old_euid,
int old_suid)
{
if ((old_ruid == 0 || old_euid == 0 || old_suid == 0) &&
(current->uid != 0 && current->euid != 0 && current->suid != 0) &&
!current->keep_capabilities) {
cap_clear (current->cap_permitted);
cap_clear (current->cap_effective);
}
if (old_euid == 0 && current->euid != 0) {
cap_clear (current->cap_effective);
}
if (old_euid != 0 && current->euid == 0) {
current->cap_effective = current->cap_permitted;
}
}
int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid,
int flags)
{
switch (flags) {
case LSM_SETID_RE:
case LSM_SETID_ID:
case LSM_SETID_RES:
/* Copied from kernel/sys.c:setreuid/setuid/setresuid. */
if (!issecure (SECURE_NO_SETUID_FIXUP)) {
cap_emulate_setxuid (old_ruid, old_euid, old_suid);
}
break;
case LSM_SETID_FS:
{
uid_t old_fsuid = old_ruid;
/* Copied from kernel/sys.c:setfsuid. */
/*
* 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)) {
if (old_fsuid == 0 && current->fsuid != 0) {
cap_t (current->cap_effective) &=
~CAP_FS_MASK;
}
if (old_fsuid != 0 && current->fsuid == 0) {
cap_t (current->cap_effective) |=
(cap_t (current->cap_permitted) &
CAP_FS_MASK);
}
}
break;
}
default:
return -EINVAL;
}
return 0;
}
void cap_task_reparent_to_init (struct task_struct *p)
{
p->cap_effective = CAP_INIT_EFF_SET;
p->cap_inheritable = CAP_INIT_INH_SET;
p->cap_permitted = CAP_FULL_SET;
p->keep_capabilities = 0;
return;
}
int cap_syslog (int type)
{
if ((type != 3) && !capable(CAP_SYS_ADMIN))
return -EPERM;
return 0;
}
/*
* Check that a process has enough memory to allocate a new virtual
* mapping. 0 means there is enough memory for the allocation to
* succeed and -ENOMEM implies there is not.
*
* We currently support three overcommit policies, which are set via the
* vm.overcommit_memory sysctl. See Documentation/vm/overcommit-acounting
*
* Strict overcommit modes added 2002 Feb 26 by Alan Cox.
* Additional code 2002 Jul 20 by Robert Love.
*/
int cap_vm_enough_memory(long pages)
{
unsigned long free, allowed;
vm_acct_memory(pages);
/* We estimate memory ourselves (common case) */
if (sysctl_overcommit_memory == 0) {
free = get_page_cache_size();
free += nr_free_pages();
free += nr_swap_pages;
/*
* Any slabs which are created with the
* SLAB_RECLAIM_ACCOUNT flag claim to have contents
* which are reclaimable, under pressure. The dentry
* cache and most inode caches should fall into this
*/
free += atomic_read(&slab_reclaim_pages);
/*
* Leave the last 3% for root
*/
if (!capable(CAP_SYS_ADMIN))
free -= free / 32;
if (free > pages)
return 0;
vm_unacct_memory(pages);
return -ENOMEM;
}
/* Kernel assumes allocation */
if (sysctl_overcommit_memory == 1)
return 0;
/* sysctl_overcommit_memory must be 2 which means strict_overcommit*/
allowed = totalram_pages * sysctl_overcommit_ratio / 100;
allowed += total_swap_pages;
if (atomic_read(&vm_committed_space) < allowed)
return 0;
vm_unacct_memory(pages);
return -ENOMEM;
}
EXPORT_SYMBOL(cap_capable);
EXPORT_SYMBOL(cap_ptrace);
EXPORT_SYMBOL(cap_capget);
EXPORT_SYMBOL(cap_capset_check);
EXPORT_SYMBOL(cap_capset_set);
EXPORT_SYMBOL(cap_bprm_set_security);
EXPORT_SYMBOL(cap_bprm_compute_creds);
EXPORT_SYMBOL(cap_bprm_secureexec);
EXPORT_SYMBOL(cap_task_post_setuid);
EXPORT_SYMBOL(cap_task_reparent_to_init);
EXPORT_SYMBOL(cap_syslog);
EXPORT_SYMBOL(cap_vm_enough_memory);
#ifdef CONFIG_SECURITY
......
security/commoncap.c 0 → 100644
View file @ e984a6dc
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