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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /security/commoncap.c
downloadlinux-linaro-stable-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'security/commoncap.c')
-rw-r--r--security/commoncap.c345
1 files changed, 345 insertions, 0 deletions
diff --git a/security/commoncap.c b/security/commoncap.c
new file mode 100644
index 000000000000..849b8c338ee8
--- /dev/null
+++ b/security/commoncap.c
@@ -0,0 +1,345 @@
+/* Common capabilities, needed by capability.o and root_plug.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/config.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/security.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <linux/smp_lock.h>
+#include <linux/skbuff.h>
+#include <linux/netlink.h>
+#include <linux/ptrace.h>
+#include <linux/xattr.h>
+#include <linux/hugetlb.h>
+
+int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
+{
+ NETLINK_CB(skb).eff_cap = current->cap_effective;
+ return 0;
+}
+
+EXPORT_SYMBOL(cap_netlink_send);
+
+int cap_netlink_recv(struct sk_buff *skb)
+{
+ if (!cap_raised(NETLINK_CB(skb).eff_cap, CAP_NET_ADMIN))
+ return -EPERM;
+ return 0;
+}
+
+EXPORT_SYMBOL(cap_netlink_recv);
+
+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;
+ return -EPERM;
+}
+
+int cap_settime(struct timespec *ts, struct timezone *tz)
+{
+ if (!capable(CAP_SYS_TIME))
+ return -EPERM;
+ return 0;
+}
+
+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;
+ 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;
+}
+
+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,
+ current->cap_inheritable);
+ 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)) {
+ current->mm->dumpable = 0;
+
+ if (unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
+ if (!capable(CAP_SETUID)) {
+ bprm->e_uid = current->uid;
+ bprm->e_gid = current->gid;
+ }
+ if (!capable (CAP_SETPCAP)) {
+ new_permitted = cap_intersect (new_permitted,
+ current->cap_permitted);
+ }
+ }
+ }
+
+ current->suid = current->euid = current->fsuid = bprm->e_uid;
+ current->sgid = current->egid = current->fsgid = bprm->e_gid;
+
+ /* 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 */
+
+ 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);
+}
+
+int cap_inode_setxattr(struct dentry *dentry, char *name, void *value,
+ size_t size, int flags)
+{
+ if (!strncmp(name, XATTR_SECURITY_PREFIX,
+ sizeof(XATTR_SECURITY_PREFIX) - 1) &&
+ !capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ return 0;
+}
+
+int cap_inode_removexattr(struct dentry *dentry, char *name)
+{
+ if (!strncmp(name, XATTR_SECURITY_PREFIX,
+ sizeof(XATTR_SECURITY_PREFIX) - 1) &&
+ !capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ return 0;
+}
+
+/* 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 && type != 10) && !capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ return 0;
+}
+
+int cap_vm_enough_memory(long pages)
+{
+ int cap_sys_admin = 0;
+
+ if (cap_capable(current, CAP_SYS_ADMIN) == 0)
+ cap_sys_admin = 1;
+ return __vm_enough_memory(pages, cap_sys_admin);
+}
+
+EXPORT_SYMBOL(cap_capable);
+EXPORT_SYMBOL(cap_settime);
+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_apply_creds);
+EXPORT_SYMBOL(cap_bprm_secureexec);
+EXPORT_SYMBOL(cap_inode_setxattr);
+EXPORT_SYMBOL(cap_inode_removexattr);
+EXPORT_SYMBOL(cap_task_post_setuid);
+EXPORT_SYMBOL(cap_task_reparent_to_init);
+EXPORT_SYMBOL(cap_syslog);
+EXPORT_SYMBOL(cap_vm_enough_memory);
+
+MODULE_DESCRIPTION("Standard Linux Common Capabilities Security Module");
+MODULE_LICENSE("GPL");