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-rw-r--r--include/linux/capability.h11
-rw-r--r--include/linux/init_task.h13
-rw-r--r--include/linux/prctl.h4
-rw-r--r--include/linux/sched.h2
-rw-r--r--include/linux/security.h5
-rw-r--r--include/linux/sysctl.h3
-rw-r--r--kernel/fork.c1
-rw-r--r--kernel/sys.c13
-rw-r--r--kernel/sysctl.c35
-rw-r--r--kernel/sysctl_check.c7
-rw-r--r--security/commoncap.c44
11 files changed, 67 insertions, 71 deletions
diff --git a/include/linux/capability.h b/include/linux/capability.h
index a1d93da..ffe7bab8 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -152,7 +152,9 @@ typedef struct kernel_cap_struct {
* Transfer any capability in your permitted set to any pid,
* remove any capability in your permitted set from any pid
* With VFS support for capabilities (neither of above, but)
- * Add any capability to the current process' inheritable set
+ * Add any capability from current's capability bounding set
+ * to the current process' inheritable set
+ * Allow taking bits out of capability bounding set
*/
#define CAP_SETPCAP 8
@@ -202,7 +204,6 @@ typedef struct kernel_cap_struct {
#define CAP_IPC_OWNER 15
/* Insert and remove kernel modules - modify kernel without limit */
-/* Modify cap_bset */
#define CAP_SYS_MODULE 16
/* Allow ioperm/iopl access */
@@ -314,6 +315,10 @@ typedef struct kernel_cap_struct {
#define CAP_SETFCAP 31
+#define CAP_LAST_CAP CAP_SETFCAP
+
+#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
+
/*
* Bit location of each capability (used by user-space library and kernel)
*/
@@ -465,6 +470,8 @@ extern const kernel_cap_t __cap_init_eff_set;
int capable(int cap);
int __capable(struct task_struct *t, int cap);
+extern long cap_prctl_drop(unsigned long cap);
+
#endif /* __KERNEL__ */
#endif /* !_LINUX_CAPABILITY_H */
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index f42663e..1f74e1d 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -121,6 +121,18 @@ extern struct group_info init_groups;
#else
#define INIT_IDS
#endif
+
+#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
+/*
+ * Because of the reduced scope of CAP_SETPCAP when filesystem
+ * capabilities are in effect, it is safe to allow CAP_SETPCAP to
+ * be available in the default configuration.
+ */
+# define CAP_INIT_BSET CAP_FULL_SET
+#else
+# define CAP_INIT_BSET CAP_INIT_EFF_SET
+#endif
+
/*
* INIT_TASK is used to set up the first task table, touch at
* your own risk!. Base=0, limit=0x1fffff (=2MB)
@@ -156,6 +168,7 @@ extern struct group_info init_groups;
.cap_effective = CAP_INIT_EFF_SET, \
.cap_inheritable = CAP_INIT_INH_SET, \
.cap_permitted = CAP_FULL_SET, \
+ .cap_bset = CAP_INIT_BSET, \
.keep_capabilities = 0, \
.user = INIT_USER, \
.comm = "swapper", \
diff --git a/include/linux/prctl.h b/include/linux/prctl.h
index e2eff90..3800639 100644
--- a/include/linux/prctl.h
+++ b/include/linux/prctl.h
@@ -63,4 +63,8 @@
#define PR_GET_SECCOMP 21
#define PR_SET_SECCOMP 22
+/* Get/set the capability bounding set */
+#define PR_CAPBSET_READ 23
+#define PR_CAPBSET_DROP 24
+
#endif /* _LINUX_PRCTL_H */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c30d174..9c13be3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1098,7 +1098,7 @@ struct task_struct {
uid_t uid,euid,suid,fsuid;
gid_t gid,egid,sgid,fsgid;
struct group_info *group_info;
- kernel_cap_t cap_effective, cap_inheritable, cap_permitted;
+ kernel_cap_t cap_effective, cap_inheritable, cap_permitted, cap_bset;
unsigned keep_capabilities:1;
struct user_struct *user;
#ifdef CONFIG_KEYS
diff --git a/include/linux/security.h b/include/linux/security.h
index 9d289e7..fe52cde 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -40,11 +40,6 @@
#define ROOTCONTEXT_MNT 0x04
#define DEFCONTEXT_MNT 0x08
-/*
- * Bounding set
- */
-extern kernel_cap_t cap_bset;
-
extern unsigned securebits;
struct ctl_table;
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index bf4ae4e..571f01d 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -102,7 +102,6 @@ enum
KERN_NODENAME=7,
KERN_DOMAINNAME=8,
- KERN_CAP_BSET=14, /* int: capability bounding set */
KERN_PANIC=15, /* int: panic timeout */
KERN_REALROOTDEV=16, /* real root device to mount after initrd */
@@ -965,8 +964,6 @@ extern int proc_dostring(struct ctl_table *, int, struct file *,
void __user *, size_t *, loff_t *);
extern int proc_dointvec(struct ctl_table *, int, struct file *,
void __user *, size_t *, loff_t *);
-extern int proc_dointvec_bset(struct ctl_table *, int, struct file *,
- void __user *, size_t *, loff_t *);
extern int proc_dointvec_minmax(struct ctl_table *, int, struct file *,
void __user *, size_t *, loff_t *);
extern int proc_dointvec_jiffies(struct ctl_table *, int, struct file *,
diff --git a/kernel/fork.c b/kernel/fork.c
index 1160f87..2b55b74 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1118,6 +1118,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
#ifdef CONFIG_SECURITY
p->security = NULL;
#endif
+ p->cap_bset = current->cap_bset;
p->io_context = NULL;
p->audit_context = NULL;
cgroup_fork(p);
diff --git a/kernel/sys.c b/kernel/sys.c
index d1fe71e..4162d12 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1637,7 +1637,7 @@ asmlinkage long sys_umask(int mask)
mask = xchg(&current->fs->umask, mask & S_IRWXUGO);
return mask;
}
-
+
asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5)
{
@@ -1742,6 +1742,17 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
error = prctl_set_seccomp(arg2);
break;
+ case PR_CAPBSET_READ:
+ if (!cap_valid(arg2))
+ return -EINVAL;
+ return !!cap_raised(current->cap_bset, arg2);
+ case PR_CAPBSET_DROP:
+#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
+ return cap_prctl_drop(arg2);
+#else
+ return -EINVAL;
+#endif
+
default:
error = -EINVAL;
break;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index d0b47b8..5e2ad5b 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -419,15 +419,6 @@ static struct ctl_table kern_table[] = {
.proc_handler = &proc_dointvec,
},
#endif
-#ifdef CONFIG_SECURITY_CAPABILITIES
- {
- .procname = "cap-bound",
- .data = &cap_bset,
- .maxlen = sizeof(kernel_cap_t),
- .mode = 0600,
- .proc_handler = &proc_dointvec_bset,
- },
-#endif /* def CONFIG_SECURITY_CAPABILITIES */
#ifdef CONFIG_BLK_DEV_INITRD
{
.ctl_name = KERN_REALROOTDEV,
@@ -2096,26 +2087,6 @@ static int do_proc_dointvec_bset_conv(int *negp, unsigned long *lvalp,
return 0;
}
-#ifdef CONFIG_SECURITY_CAPABILITIES
-/*
- * init may raise the set.
- */
-
-int proc_dointvec_bset(struct ctl_table *table, int write, struct file *filp,
- void __user *buffer, size_t *lenp, loff_t *ppos)
-{
- int op;
-
- if (write && !capable(CAP_SYS_MODULE)) {
- return -EPERM;
- }
-
- op = is_global_init(current) ? OP_SET : OP_AND;
- return do_proc_dointvec(table,write,filp,buffer,lenp,ppos,
- do_proc_dointvec_bset_conv,&op);
-}
-#endif /* def CONFIG_SECURITY_CAPABILITIES */
-
/*
* Taint values can only be increased
*/
@@ -2529,12 +2500,6 @@ int proc_dointvec(struct ctl_table *table, int write, struct file *filp,
return -ENOSYS;
}
-int proc_dointvec_bset(struct ctl_table *table, int write, struct file *filp,
- void __user *buffer, size_t *lenp, loff_t *ppos)
-{
- return -ENOSYS;
-}
-
int proc_dointvec_minmax(struct ctl_table *table, int write, struct file *filp,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
diff --git a/kernel/sysctl_check.c b/kernel/sysctl_check.c
index c3206fa..006365b 100644
--- a/kernel/sysctl_check.c
+++ b/kernel/sysctl_check.c
@@ -37,10 +37,6 @@ static struct trans_ctl_table trans_kern_table[] = {
{ KERN_NODENAME, "hostname" },
{ KERN_DOMAINNAME, "domainname" },
-#ifdef CONFIG_SECURITY_CAPABILITIES
- { KERN_CAP_BSET, "cap-bound" },
-#endif /* def CONFIG_SECURITY_CAPABILITIES */
-
{ KERN_PANIC, "panic" },
{ KERN_REALROOTDEV, "real-root-dev" },
@@ -1498,9 +1494,6 @@ int sysctl_check_table(struct nsproxy *namespaces, struct ctl_table *table)
(table->strategy == sysctl_ms_jiffies) ||
(table->proc_handler == proc_dostring) ||
(table->proc_handler == proc_dointvec) ||
-#ifdef CONFIG_SECURITY_CAPABILITIES
- (table->proc_handler == proc_dointvec_bset) ||
-#endif /* def CONFIG_SECURITY_CAPABILITIES */
(table->proc_handler == proc_dointvec_minmax) ||
(table->proc_handler == proc_dointvec_jiffies) ||
(table->proc_handler == proc_dointvec_userhz_jiffies) ||
diff --git a/security/commoncap.c b/security/commoncap.c
index 01ab478..5aba826 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -25,20 +25,6 @@
#include <linux/mount.h>
#include <linux/sched.h>
-#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
-/*
- * Because of the reduced scope of CAP_SETPCAP when filesystem
- * capabilities are in effect, it is safe to allow this capability to
- * be available in the default configuration.
- */
-# define CAP_INIT_BSET CAP_FULL_SET
-#else /* ie. ndef CONFIG_SECURITY_FILE_CAPABILITIES */
-# define CAP_INIT_BSET CAP_INIT_EFF_SET
-#endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
-
-kernel_cap_t cap_bset = CAP_INIT_BSET; /* systemwide capability bound */
-EXPORT_SYMBOL(cap_bset);
-
/* Global security state */
unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
@@ -140,6 +126,12 @@ int cap_capset_check (struct task_struct *target, kernel_cap_t *effective,
/* incapable of using this inheritable set */
return -EPERM;
}
+ if (!cap_issubset(*inheritable,
+ cap_combine(target->cap_inheritable,
+ current->cap_bset))) {
+ /* no new pI capabilities outside bounding set */
+ return -EPERM;
+ }
/* verify restrictions on target's new Permitted set */
if (!cap_issubset (*permitted,
@@ -337,10 +329,11 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
/* 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,
+ new_permitted = cap_intersect(bprm->cap_permitted,
+ current->cap_bset);
+ working = cap_intersect(bprm->cap_inheritable,
current->cap_inheritable);
- new_permitted = cap_combine (new_permitted, working);
+ new_permitted = cap_combine(new_permitted, working);
if (bprm->e_uid != current->uid || bprm->e_gid != current->gid ||
!cap_issubset (new_permitted, current->cap_permitted)) {
@@ -581,6 +574,23 @@ int cap_task_kill(struct task_struct *p, struct siginfo *info,
return -EPERM;
}
+
+/*
+ * called from kernel/sys.c for prctl(PR_CABSET_DROP)
+ * done without task_capability_lock() because it introduces
+ * no new races - i.e. only another task doing capget() on
+ * this task could get inconsistent info. There can be no
+ * racing writer bc a task can only change its own caps.
+ */
+long cap_prctl_drop(unsigned long cap)
+{
+ if (!capable(CAP_SETPCAP))
+ return -EPERM;
+ if (!cap_valid(cap))
+ return -EINVAL;
+ cap_lower(current->cap_bset, cap);
+ return 0;
+}
#else
int cap_task_setscheduler (struct task_struct *p, int policy,
struct sched_param *lp)
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