/* 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/capability.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/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> #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 */ EXPORT_SYMBOL(securebits); int cap_netlink_send(struct sock *sk, struct sk_buff *skb) { NETLINK_CB(skb).eff_cap = current->cap_effective; return 0; } int cap_netlink_recv(struct sk_buff *skb, int cap) { if (!cap_raised(NETLINK_CB(skb).eff_cap, cap)) 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, parent->cap_permitted) && !__capable(parent, 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; } #ifdef CONFIG_SECURITY_FILE_CAPABILITIES static inline int cap_block_setpcap(struct task_struct *target) { /* * No support for remote process capability manipulation with * filesystem capability support. */ return (target != current); } static inline int cap_inh_is_capped(void) { /* * return 1 if changes to the inheritable set are limited * to the old permitted set. */ return !cap_capable(current, CAP_SETPCAP); } #else /* ie., ndef CONFIG_SECURITY_FILE_CAPABILITIES */ static inline int cap_block_setpcap(struct task_struct *t) { return 0; } static inline int cap_inh_is_capped(void) { return 1; } #endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */ int cap_capset_check (struct task_struct *target, kernel_cap_t *effective, kernel_cap_t *inheritable, kernel_cap_t *permitted) { if (cap_block_setpcap(target)) { return -EPERM; } if (cap_inh_is_capped() && !cap_issubset(*inheritable, cap_combine(target->cap_inheritable, current->cap_permitted))) { /* incapable of using this inheritable set */ 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; } static inline void bprm_clear_caps(struct linux_binprm *bprm) { cap_clear(bprm->cap_inheritable); cap_clear(bprm->cap_permitted); bprm->cap_effective = false; } #ifdef CONFIG_SECURITY_FILE_CAPABILITIES int cap_inode_need_killpriv(struct dentry *dentry) { struct inode *inode = dentry->d_inode; int error; if (!inode->i_op || !inode->i_op->getxattr) return 0; error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0); if (error <= 0) return 0; return 1; } int cap_inode_killpriv(struct dentry *dentry) { struct inode *inode = dentry->d_inode; if (!inode->i_op || !inode->i_op->removexattr) return 0; return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS); } static inline int cap_from_disk(struct vfs_cap_data *caps, struct linux_binprm *bprm, int size) { __u32 magic_etc; if (size != XATTR_CAPS_SZ) return -EINVAL; magic_etc = le32_to_cpu(caps->magic_etc); switch ((magic_etc & VFS_CAP_REVISION_MASK)) { case VFS_CAP_REVISION: if (magic_etc & VFS_CAP_FLAGS_EFFECTIVE) bprm->cap_effective = true; else bprm->cap_effective = false; bprm->cap_permitted = to_cap_t(le32_to_cpu(caps->permitted)); bprm->cap_inheritable = to_cap_t(le32_to_cpu(caps->inheritable)); return 0; default: return -EINVAL; } } /* Locate any VFS capabilities: */ static int get_file_caps(struct linux_binprm *bprm) { struct dentry *dentry; int rc = 0; struct vfs_cap_data incaps; struct inode *inode; if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID) { bprm_clear_caps(bprm); return 0; } dentry = dget(bprm->file->f_dentry); inode = dentry->d_inode; if (!inode->i_op || !inode->i_op->getxattr) goto out; rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0); if (rc > 0) { if (rc == XATTR_CAPS_SZ) rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, &incaps, XATTR_CAPS_SZ); else rc = -EINVAL; } if (rc == -ENODATA || rc == -EOPNOTSUPP) { /* no data, that's ok */ rc = 0; goto out; } if (rc < 0) goto out; rc = cap_from_disk(&incaps, bprm, rc); if (rc) printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n", __FUNCTION__, rc, bprm->filename); out: dput(dentry); if (rc) bprm_clear_caps(bprm); return rc; } #else int cap_inode_need_killpriv(struct dentry *dentry) { return 0; } int cap_inode_killpriv(struct dentry *dentry) { return 0; } static inline int get_file_caps(struct linux_binprm *bprm) { bprm_clear_caps(bprm); return 0; } #endif int cap_bprm_set_security (struct linux_binprm *bprm) { int ret; ret = get_file_caps(bprm); if (ret) printk(KERN_NOTICE "%s: get_file_caps returned %d for %s\n", __FUNCTION__, ret, bprm->filename); /* 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) bprm->cap_effective = true; } return ret; } 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)) { set_dumpable(current->mm, suid_dumpable); current->pdeath_signal = 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 (!is_global_init(current)) { current->cap_permitted = new_permitted; current->cap_effective = bprm->cap_effective ? new_permitted : 0; } /* AUD: Audit candidate if current->cap_effective is set */ current->keep_capabilities = 0; } int cap_bprm_secureexec (struct linux_binprm *bprm) { if (current->uid != 0) { if (bprm->cap_effective) return 1; if (!cap_isclear(bprm->cap_permitted)) return 1; if (!cap_isclear(bprm->cap_inheritable)) return 1; } 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 (!strcmp(name, XATTR_NAME_CAPS)) { if (!capable(CAP_SETFCAP)) return -EPERM; return 0; } else 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 (!strcmp(name, XATTR_NAME_CAPS)) { if (!capable(CAP_SETFCAP)) return -EPERM; return 0; } else 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; } #ifdef CONFIG_SECURITY_FILE_CAPABILITIES /* * 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 inline int cap_safe_nice(struct task_struct *p) { if (!cap_issubset(p->cap_permitted, current->cap_permitted) && !__capable(current, CAP_SYS_NICE)) return -EPERM; return 0; } int cap_task_setscheduler (struct task_struct *p, int policy, struct sched_param *lp) { return cap_safe_nice(p); } int cap_task_setioprio (struct task_struct *p, int ioprio) { return cap_safe_nice(p); } int cap_task_setnice (struct task_struct *p, int nice) { return cap_safe_nice(p); } int cap_task_kill(struct task_struct *p, struct siginfo *info, int sig, u32 secid) { if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info))) return 0; if (secid) /* * Signal sent as a particular user. * Capabilities are ignored. May be wrong, but it's the * only thing we can do at the moment. * Used only by usb drivers? */ return 0; if (cap_issubset(p->cap_permitted, current->cap_permitted)) return 0; if (capable(CAP_KILL)) return 0; return -EPERM; } #else int cap_task_setscheduler (struct task_struct *p, int policy, struct sched_param *lp) { return 0; } int cap_task_setioprio (struct task_struct *p, int ioprio) { return 0; } int cap_task_setnice (struct task_struct *p, int nice) { return 0; } int cap_task_kill(struct task_struct *p, struct siginfo *info, int sig, u32 secid) { return 0; } #endif 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(struct mm_struct *mm, long pages) { int cap_sys_admin = 0; if (cap_capable(current, CAP_SYS_ADMIN) == 0) cap_sys_admin = 1; return __vm_enough_memory(mm, pages, cap_sys_admin); }