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-rw-r--r--include/linux/capability.h3
-rw-r--r--include/linux/init_task.h3
-rw-r--r--include/linux/prctl.h9
-rw-r--r--include/linux/sched.h3
-rw-r--r--include/linux/securebits.h25
-rw-r--r--include/linux/security.h16
-rw-r--r--kernel/sys.c27
-rw-r--r--security/capability.c1
-rw-r--r--security/commoncap.c103
-rw-r--r--security/dummy.c2
-rw-r--r--security/security.c4
-rw-r--r--security/selinux/hooks.c5
12 files changed, 141 insertions, 60 deletions
diff --git a/include/linux/capability.h b/include/linux/capability.h
index 7d50ff6d269..eaab759b146 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -155,6 +155,7 @@ typedef struct kernel_cap_struct {
* Add any capability from current's capability bounding set
* to the current process' inheritable set
* Allow taking bits out of capability bounding set
+ * Allow modification of the securebits for a process
*/
#define CAP_SETPCAP 8
@@ -490,8 +491,6 @@ 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 37a6f5bc4a9..bf6b8a61f8d 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -9,6 +9,7 @@
#include <linux/ipc.h>
#include <linux/pid_namespace.h>
#include <linux/user_namespace.h>
+#include <linux/securebits.h>
#include <net/net_namespace.h>
#define INIT_FDTABLE \
@@ -172,7 +173,7 @@ extern struct group_info init_groups;
.cap_inheritable = CAP_INIT_INH_SET, \
.cap_permitted = CAP_FULL_SET, \
.cap_bset = CAP_INIT_BSET, \
- .keep_capabilities = 0, \
+ .securebits = SECUREBITS_DEFAULT, \
.user = INIT_USER, \
.comm = "swapper", \
.thread = INIT_THREAD, \
diff --git a/include/linux/prctl.h b/include/linux/prctl.h
index 5c80b193963..5ad79198d6f 100644
--- a/include/linux/prctl.h
+++ b/include/linux/prctl.h
@@ -16,7 +16,8 @@
# define PR_UNALIGN_NOPRINT 1 /* silently fix up unaligned user accesses */
# define PR_UNALIGN_SIGBUS 2 /* generate SIGBUS on unaligned user access */
-/* Get/set whether or not to drop capabilities on setuid() away from uid 0 */
+/* Get/set whether or not to drop capabilities on setuid() away from
+ * uid 0 (as per security/commoncap.c) */
#define PR_GET_KEEPCAPS 7
#define PR_SET_KEEPCAPS 8
@@ -63,7 +64,7 @@
#define PR_GET_SECCOMP 21
#define PR_SET_SECCOMP 22
-/* Get/set the capability bounding set */
+/* Get/set the capability bounding set (as per security/commoncap.c) */
#define PR_CAPBSET_READ 23
#define PR_CAPBSET_DROP 24
@@ -73,4 +74,8 @@
# define PR_TSC_ENABLE 1 /* allow the use of the timestamp counter */
# define PR_TSC_SIGSEGV 2 /* throw a SIGSEGV instead of reading the TSC */
+/* Get/set securebits (as per security/commoncap.c) */
+#define PR_GET_SECUREBITS 27
+#define PR_SET_SECUREBITS 28
+
#endif /* _LINUX_PRCTL_H */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 9a4f3e63e3b..024d72b47a0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -68,7 +68,6 @@ struct sched_param {
#include <linux/smp.h>
#include <linux/sem.h>
#include <linux/signal.h>
-#include <linux/securebits.h>
#include <linux/fs_struct.h>
#include <linux/compiler.h>
#include <linux/completion.h>
@@ -1133,7 +1132,7 @@ struct task_struct {
gid_t gid,egid,sgid,fsgid;
struct group_info *group_info;
kernel_cap_t cap_effective, cap_inheritable, cap_permitted, cap_bset;
- unsigned keep_capabilities:1;
+ unsigned securebits;
struct user_struct *user;
#ifdef CONFIG_KEYS
struct key *request_key_auth; /* assumed request_key authority */
diff --git a/include/linux/securebits.h b/include/linux/securebits.h
index 5b0617840fa..c1f19dbceb0 100644
--- a/include/linux/securebits.h
+++ b/include/linux/securebits.h
@@ -3,28 +3,39 @@
#define SECUREBITS_DEFAULT 0x00000000
-extern unsigned securebits;
-
/* When set UID 0 has no special privileges. When unset, we support
inheritance of root-permissions and suid-root executable under
compatibility mode. We raise the effective and inheritable bitmasks
*of the executable file* if the effective uid of the new process is
0. If the real uid is 0, we raise the inheritable bitmask of the
executable file. */
-#define SECURE_NOROOT 0
+#define SECURE_NOROOT 0
+#define SECURE_NOROOT_LOCKED 1 /* make bit-0 immutable */
/* When set, setuid to/from uid 0 does not trigger capability-"fixes"
to be compatible with old programs relying on set*uid to loose
privileges. When unset, setuid doesn't change privileges. */
-#define SECURE_NO_SETUID_FIXUP 2
+#define SECURE_NO_SETUID_FIXUP 2
+#define SECURE_NO_SETUID_FIXUP_LOCKED 3 /* make bit-2 immutable */
+
+/* When set, a process can retain its capabilities even after
+ transitioning to a non-root user (the set-uid fixup suppressed by
+ bit 2). Bit-4 is cleared when a process calls exec(); setting both
+ bit 4 and 5 will create a barrier through exec that no exec()'d
+ child can use this feature again. */
+#define SECURE_KEEP_CAPS 4
+#define SECURE_KEEP_CAPS_LOCKED 5 /* make bit-4 immutable */
/* Each securesetting is implemented using two bits. One bit specify
whether the setting is on or off. The other bit specify whether the
setting is fixed or not. A setting which is fixed cannot be changed
from user-level. */
+#define issecure_mask(X) (1 << (X))
+#define issecure(X) (issecure_mask(X) & current->securebits)
-#define issecure(X) ( (1 << (X+1)) & SECUREBITS_DEFAULT ? \
- (1 << (X)) & SECUREBITS_DEFAULT : \
- (1 << (X)) & securebits )
+#define SECURE_ALL_BITS (issecure_mask(SECURE_NOROOT) | \
+ issecure_mask(SECURE_NO_SETUID_FIXUP) | \
+ issecure_mask(SECURE_KEEP_CAPS))
+#define SECURE_ALL_LOCKS (SECURE_ALL_BITS << 1)
#endif /* !_LINUX_SECUREBITS_H */
diff --git a/include/linux/security.h b/include/linux/security.h
index 53a34539382..e6299e50e21 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -34,8 +34,6 @@
#include <linux/xfrm.h>
#include <net/flow.h>
-extern unsigned securebits;
-
/* Maximum number of letters for an LSM name string */
#define SECURITY_NAME_MAX 10
@@ -61,6 +59,8 @@ extern int cap_inode_need_killpriv(struct dentry *dentry);
extern int cap_inode_killpriv(struct dentry *dentry);
extern int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid, int flags);
extern void cap_task_reparent_to_init (struct task_struct *p);
+extern int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5, long *rc_p);
extern int cap_task_setscheduler (struct task_struct *p, int policy, struct sched_param *lp);
extern int cap_task_setioprio (struct task_struct *p, int ioprio);
extern int cap_task_setnice (struct task_struct *p, int nice);
@@ -720,7 +720,9 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
* @arg3 contains a argument.
* @arg4 contains a argument.
* @arg5 contains a argument.
- * Return 0 if permission is granted.
+ * @rc_p contains a pointer to communicate back the forced return code
+ * Return 0 if permission is granted, and non-zero if the security module
+ * has taken responsibility (setting *rc_p) for the prctl call.
* @task_reparent_to_init:
* Set the security attributes in @p->security for a kernel thread that
* is being reparented to the init task.
@@ -1420,7 +1422,7 @@ struct security_operations {
int (*task_wait) (struct task_struct * p);
int (*task_prctl) (int option, unsigned long arg2,
unsigned long arg3, unsigned long arg4,
- unsigned long arg5);
+ unsigned long arg5, long *rc_p);
void (*task_reparent_to_init) (struct task_struct * p);
void (*task_to_inode)(struct task_struct *p, struct inode *inode);
@@ -1684,7 +1686,7 @@ int security_task_kill(struct task_struct *p, struct siginfo *info,
int sig, u32 secid);
int security_task_wait(struct task_struct *p);
int security_task_prctl(int option, unsigned long arg2, unsigned long arg3,
- unsigned long arg4, unsigned long arg5);
+ unsigned long arg4, unsigned long arg5, long *rc_p);
void security_task_reparent_to_init(struct task_struct *p);
void security_task_to_inode(struct task_struct *p, struct inode *inode);
int security_ipc_permission(struct kern_ipc_perm *ipcp, short flag);
@@ -2271,9 +2273,9 @@ static inline int security_task_wait (struct task_struct *p)
static inline int security_task_prctl (int option, unsigned long arg2,
unsigned long arg3,
unsigned long arg4,
- unsigned long arg5)
+ unsigned long arg5, long *rc_p)
{
- return 0;
+ return cap_task_prctl(option, arg2, arg3, arg3, arg5, rc_p);
}
static inline void security_task_reparent_to_init (struct task_struct *p)
diff --git a/kernel/sys.c b/kernel/sys.c
index 6a0cc71ee88..f2a45136695 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1632,10 +1632,9 @@ asmlinkage long sys_umask(int mask)
asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5)
{
- long error;
+ long uninitialized_var(error);
- error = security_task_prctl(option, arg2, arg3, arg4, arg5);
- if (error)
+ if (security_task_prctl(option, arg2, arg3, arg4, arg5, &error))
return error;
switch (option) {
@@ -1688,17 +1687,6 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
error = -EINVAL;
break;
- case PR_GET_KEEPCAPS:
- if (current->keep_capabilities)
- error = 1;
- break;
- case PR_SET_KEEPCAPS:
- if (arg2 != 0 && arg2 != 1) {
- error = -EINVAL;
- break;
- }
- current->keep_capabilities = arg2;
- break;
case PR_SET_NAME: {
struct task_struct *me = current;
unsigned char ncomm[sizeof(me->comm)];
@@ -1732,17 +1720,6 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
case PR_SET_SECCOMP:
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
case PR_GET_TSC:
error = GET_TSC_CTL(arg2);
break;
diff --git a/security/capability.c b/security/capability.c
index 2c6e06d18fa..38ac54e3aed 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -44,6 +44,7 @@ static struct security_operations capability_ops = {
.task_setioprio = cap_task_setioprio,
.task_setnice = cap_task_setnice,
.task_post_setuid = cap_task_post_setuid,
+ .task_prctl = cap_task_prctl,
.task_reparent_to_init = cap_task_reparent_to_init,
.syslog = cap_syslog,
diff --git a/security/commoncap.c b/security/commoncap.c
index 852905789ca..e8c3f5e4670 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -24,11 +24,8 @@
#include <linux/hugetlb.h>
#include <linux/mount.h>
#include <linux/sched.h>
-
-/* Global security state */
-
-unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
-EXPORT_SYMBOL(securebits);
+#include <linux/prctl.h>
+#include <linux/securebits.h>
int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
{
@@ -368,7 +365,7 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
/* AUD: Audit candidate if current->cap_effective is set */
- current->keep_capabilities = 0;
+ current->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
}
int cap_bprm_secureexec (struct linux_binprm *bprm)
@@ -448,7 +445,7 @@ static inline void cap_emulate_setxuid (int old_ruid, int old_euid,
{
if ((old_ruid == 0 || old_euid == 0 || old_suid == 0) &&
(current->uid != 0 && current->euid != 0 && current->suid != 0) &&
- !current->keep_capabilities) {
+ !issecure(SECURE_KEEP_CAPS)) {
cap_clear (current->cap_permitted);
cap_clear (current->cap_effective);
}
@@ -547,7 +544,7 @@ int cap_task_setnice (struct task_struct *p, int nice)
* 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)
+static long cap_prctl_drop(unsigned long cap)
{
if (!capable(CAP_SETPCAP))
return -EPERM;
@@ -556,6 +553,7 @@ long cap_prctl_drop(unsigned long cap)
cap_lower(current->cap_bset, cap);
return 0;
}
+
#else
int cap_task_setscheduler (struct task_struct *p, int policy,
struct sched_param *lp)
@@ -572,12 +570,99 @@ int cap_task_setnice (struct task_struct *p, int nice)
}
#endif
+int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5, long *rc_p)
+{
+ long error = 0;
+
+ switch (option) {
+ case PR_CAPBSET_READ:
+ if (!cap_valid(arg2))
+ error = -EINVAL;
+ else
+ error = !!cap_raised(current->cap_bset, arg2);
+ break;
+#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
+ case PR_CAPBSET_DROP:
+ error = cap_prctl_drop(arg2);
+ break;
+
+ /*
+ * 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 ((((current->securebits & SECURE_ALL_LOCKS) >> 1)
+ & (current->securebits ^ arg2)) /*[1]*/
+ || ((current->securebits & SECURE_ALL_LOCKS
+ & ~arg2)) /*[2]*/
+ || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
+ || (cap_capable(current, CAP_SETPCAP) != 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")
+ */
+ error = -EPERM; /* cannot change a locked bit */
+ } else {
+ current->securebits = arg2;
+ }
+ break;
+ case PR_GET_SECUREBITS:
+ error = current->securebits;
+ break;
+
+#endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
+
+ case PR_GET_KEEPCAPS:
+ if (issecure(SECURE_KEEP_CAPS))
+ error = 1;
+ break;
+ case PR_SET_KEEPCAPS:
+ if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
+ error = -EINVAL;
+ else if (issecure(SECURE_KEEP_CAPS_LOCKED))
+ error = -EPERM;
+ else if (arg2)
+ current->securebits |= issecure_mask(SECURE_KEEP_CAPS);
+ else
+ current->securebits &=
+ ~issecure_mask(SECURE_KEEP_CAPS);
+ break;
+
+ default:
+ /* No functionality available - continue with default */
+ return 0;
+ }
+
+ /* Functionality provided */
+ *rc_p = error;
+ return 1;
+}
+
void cap_task_reparent_to_init (struct task_struct *p)
{
cap_set_init_eff(p->cap_effective);
cap_clear(p->cap_inheritable);
cap_set_full(p->cap_permitted);
- p->keep_capabilities = 0;
+ p->securebits = SECUREBITS_DEFAULT;
return;
}
diff --git a/security/dummy.c b/security/dummy.c
index b0232bbf427..58d4dd1af5c 100644
--- a/security/dummy.c
+++ b/security/dummy.c
@@ -604,7 +604,7 @@ static int dummy_task_kill (struct task_struct *p, struct siginfo *info,
}
static int dummy_task_prctl (int option, unsigned long arg2, unsigned long arg3,
- unsigned long arg4, unsigned long arg5)
+ unsigned long arg4, unsigned long arg5, long *rc_p)
{
return 0;
}
diff --git a/security/security.c b/security/security.c
index 8a285c7b996..d5cb5898d96 100644
--- a/security/security.c
+++ b/security/security.c
@@ -733,9 +733,9 @@ int security_task_wait(struct task_struct *p)
}
int security_task_prctl(int option, unsigned long arg2, unsigned long arg3,
- unsigned long arg4, unsigned long arg5)
+ unsigned long arg4, unsigned long arg5, long *rc_p)
{
- return security_ops->task_prctl(option, arg2, arg3, arg4, arg5);
+ return security_ops->task_prctl(option, arg2, arg3, arg4, arg5, rc_p);
}
void security_task_reparent_to_init(struct task_struct *p)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 308e2cf17d7..04acb5af831 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3303,12 +3303,13 @@ static int selinux_task_prctl(int option,
unsigned long arg2,
unsigned long arg3,
unsigned long arg4,
- unsigned long arg5)
+ unsigned long arg5,
+ long *rc_p)
{
/* The current prctl operations do not appear to require
any SELinux controls since they merely observe or modify
the state of the current process. */
- return 0;
+ return secondary_ops->task_prctl(option, arg2, arg3, arg4, arg5, rc_p);
}
static int selinux_task_wait(struct task_struct *p)
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-02 19:27:42 +0000