diff options
Diffstat (limited to 'security/commoncap.c')
| -rw-r--r-- | security/commoncap.c | 232 |
1 files changed, 138 insertions, 94 deletions
diff --git a/security/commoncap.c b/security/commoncap.c index 04b80f9912b..b9d613e0ef1 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -27,7 +27,9 @@ #include <linux/sched.h> #include <linux/prctl.h> #include <linux/securebits.h> -#include <linux/syslog.h> +#include <linux/user_namespace.h> +#include <linux/binfmts.h> +#include <linux/personality.h> /* * If a non-root user executes a setuid-root binary in @@ -53,22 +55,13 @@ static void warn_setuid_and_fcaps_mixed(const char *fname) int cap_netlink_send(struct sock *sk, struct sk_buff *skb) { - NETLINK_CB(skb).eff_cap = current_cap(); 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); - /** * cap_capable - Determine whether a task has a particular effective capability - * @tsk: The task to query * @cred: The credentials to use + * @ns: The user namespace in which we need the capability * @cap: The capability to check for * @audit: Whether to write an audit message or not * @@ -80,10 +73,39 @@ EXPORT_SYMBOL(cap_netlink_recv); * cap_has_capability() returns 0 when a task has a capability, but the * kernel's capable() and has_capability() returns 1 for this case. */ -int cap_capable(struct task_struct *tsk, const struct cred *cred, int cap, - int audit) +int cap_capable(const struct cred *cred, struct user_namespace *targ_ns, + int cap, int audit) { - return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM; + struct user_namespace *ns = targ_ns; + + /* See if cred has the capability in the target user namespace + * by examining the target user namespace and all of the target + * user namespace's parents. + */ + for (;;) { + /* Do we have the necessary capabilities? */ + if (ns == cred->user_ns) + return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM; + + /* Have we tried all of the parent namespaces? */ + if (ns == &init_user_ns) + return -EPERM; + + /* + * The owner of the user namespace in the parent of the + * user namespace has all caps. + */ + if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid)) + return 0; + + /* + * If you have a capability in a parent user ns, then you have + * it over all children user namespaces as well. + */ + ns = ns->parent; + } + + /* We never get here */ } /** @@ -94,7 +116,7 @@ int cap_capable(struct task_struct *tsk, const struct cred *cred, int cap, * Determine whether the current process may set the system clock and timezone * information, returning 0 if permission granted, -ve if denied. */ -int cap_settime(struct timespec *ts, struct timezone *tz) +int cap_settime(const struct timespec *ts, const struct timezone *tz) { if (!capable(CAP_SYS_TIME)) return -EPERM; @@ -107,18 +129,30 @@ int cap_settime(struct timespec *ts, struct timezone *tz) * @child: The process to be accessed * @mode: The mode of attachment. * + * If we are in the same or an ancestor user_ns and have all the target + * task's capabilities, then ptrace access is allowed. + * If we have the ptrace capability to the target user_ns, then ptrace + * access is allowed. + * Else denied. + * * Determine whether a process may access another, returning 0 if permission * granted, -ve if denied. */ int cap_ptrace_access_check(struct task_struct *child, unsigned int mode) { int ret = 0; + const struct cred *cred, *child_cred; rcu_read_lock(); - if (!cap_issubset(__task_cred(child)->cap_permitted, - current_cred()->cap_permitted) && - !capable(CAP_SYS_PTRACE)) - ret = -EPERM; + cred = current_cred(); + child_cred = __task_cred(child); + if (cred->user_ns == child_cred->user_ns && + cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) + goto out; + if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE)) + goto out; + ret = -EPERM; +out: rcu_read_unlock(); return ret; } @@ -127,18 +161,30 @@ int cap_ptrace_access_check(struct task_struct *child, unsigned int mode) * cap_ptrace_traceme - Determine whether another process may trace the current * @parent: The task proposed to be the tracer * + * If parent is in the same or an ancestor user_ns and has all current's + * capabilities, then ptrace access is allowed. + * If parent has the ptrace capability to current's user_ns, then ptrace + * access is allowed. + * Else denied. + * * Determine whether the nominated task is permitted to trace the current * process, returning 0 if permission is granted, -ve if denied. */ int cap_ptrace_traceme(struct task_struct *parent) { int ret = 0; + const struct cred *cred, *child_cred; rcu_read_lock(); - if (!cap_issubset(current_cred()->cap_permitted, - __task_cred(parent)->cap_permitted) && - !has_capability(parent, CAP_SYS_PTRACE)) - ret = -EPERM; + cred = __task_cred(parent); + child_cred = current_cred(); + if (cred->user_ns == child_cred->user_ns && + cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) + goto out; + if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE)) + goto out; + ret = -EPERM; +out: rcu_read_unlock(); return ret; } @@ -178,8 +224,8 @@ static inline int cap_inh_is_capped(void) /* they are so limited unless the current task has the CAP_SETPCAP * capability */ - if (cap_capable(current, current_cred(), CAP_SETPCAP, - SECURITY_CAP_AUDIT) == 0) + if (cap_capable(current_cred(), current_cred()->user_ns, + CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0) return 0; return 1; } @@ -287,7 +333,8 @@ int cap_inode_killpriv(struct dentry *dentry) */ static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps, struct linux_binprm *bprm, - bool *effective) + bool *effective, + bool *has_cap) { struct cred *new = bprm->cred; unsigned i; @@ -296,6 +343,9 @@ static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps, if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE) *effective = true; + if (caps->magic_etc & VFS_CAP_REVISION_MASK) + *has_cap = true; + CAP_FOR_EACH_U32(i) { __u32 permitted = caps->permitted.cap[i]; __u32 inheritable = caps->inheritable.cap[i]; @@ -379,7 +429,7 @@ int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data * its xattrs and, if present, apply them to the proposed credentials being * constructed by execve(). */ -static int get_file_caps(struct linux_binprm *bprm, bool *effective) +static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_cap) { struct dentry *dentry; int rc = 0; @@ -390,7 +440,7 @@ static int get_file_caps(struct linux_binprm *bprm, bool *effective) if (!file_caps_enabled) return 0; - if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID) + if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) return 0; dentry = dget(bprm->file->f_dentry); @@ -405,7 +455,7 @@ static int get_file_caps(struct linux_binprm *bprm, bool *effective) goto out; } - rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective); + rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_cap); if (rc == -EINVAL) printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n", __func__, rc, bprm->filename); @@ -430,21 +480,24 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) { const struct cred *old = current_cred(); struct cred *new = bprm->cred; - bool effective; + bool effective, has_cap = false; int ret; + kuid_t root_uid; effective = false; - ret = get_file_caps(bprm, &effective); + ret = get_file_caps(bprm, &effective, &has_cap); if (ret < 0) return ret; + root_uid = make_kuid(new->user_ns, 0); + if (!issecure(SECURE_NOROOT)) { /* * If the legacy file capability is set, then don't set privs * for a setuid root binary run by a non-root user. Do set it * for a root user just to cause least surprise to an admin. */ - if (effective && new->uid != 0 && new->euid == 0) { + if (has_cap && !uid_eq(new->uid, root_uid) && uid_eq(new->euid, root_uid)) { warn_setuid_and_fcaps_mixed(bprm->filename); goto skip; } @@ -455,25 +508,33 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) * * If only the real uid is 0, we do not set the effective bit. */ - if (new->euid == 0 || new->uid == 0) { + if (uid_eq(new->euid, root_uid) || uid_eq(new->uid, root_uid)) { /* pP' = (cap_bset & ~0) | (pI & ~0) */ new->cap_permitted = cap_combine(old->cap_bset, old->cap_inheritable); } - if (new->euid == 0) + if (uid_eq(new->euid, root_uid)) effective = true; } skip: + /* if we have fs caps, clear dangerous personality flags */ + if (!cap_issubset(new->cap_permitted, old->cap_permitted)) + bprm->per_clear |= PER_CLEAR_ON_SETID; + + /* Don't let someone trace a set[ug]id/setpcap binary with the revised - * credentials unless they have the appropriate permit + * credentials unless they have the appropriate permit. + * + * In addition, if NO_NEW_PRIVS, then ensure we get no new privs. */ - if ((new->euid != old->uid || - new->egid != old->gid || + if ((!uid_eq(new->euid, old->uid) || + !gid_eq(new->egid, old->gid) || !cap_issubset(new->cap_permitted, old->cap_permitted)) && bprm->unsafe & ~LSM_UNSAFE_PTRACE_CAP) { /* downgrade; they get no more than they had, and maybe less */ - if (!capable(CAP_SETUID)) { + if (!capable(CAP_SETUID) || + (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) { new->euid = new->uid; new->egid = new->gid; } @@ -484,15 +545,10 @@ skip: new->suid = new->fsuid = new->euid; new->sgid = new->fsgid = new->egid; - /* For init, we want to retain the capabilities set in the initial - * task. Thus we skip the usual capability rules - */ - if (!is_global_init(current)) { - if (effective) - new->cap_effective = new->cap_permitted; - else - cap_clear(new->cap_effective); - } + if (effective) + new->cap_effective = new->cap_permitted; + else + cap_clear(new->cap_effective); bprm->cap_effective = effective; /* @@ -509,7 +565,7 @@ skip: */ if (!cap_isclear(new->cap_effective)) { if (!cap_issubset(CAP_FULL_SET, new->cap_effective) || - new->euid != 0 || new->uid != 0 || + !uid_eq(new->euid, root_uid) || !uid_eq(new->uid, root_uid) || issecure(SECURE_NOROOT)) { ret = audit_log_bprm_fcaps(bprm, new, old); if (ret < 0) @@ -534,16 +590,17 @@ skip: int cap_bprm_secureexec(struct linux_binprm *bprm) { const struct cred *cred = current_cred(); + kuid_t root_uid = make_kuid(cred->user_ns, 0); - if (cred->uid != 0) { + if (!uid_eq(cred->uid, root_uid)) { if (bprm->cap_effective) return 1; if (!cap_isclear(cred->cap_permitted)) return 1; } - return (cred->euid != cred->uid || - cred->egid != cred->gid); + return (!uid_eq(cred->euid, cred->uid) || + !gid_eq(cred->egid, cred->gid)); } /** @@ -633,15 +690,21 @@ int cap_inode_removexattr(struct dentry *dentry, const char *name) */ static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old) { - if ((old->uid == 0 || old->euid == 0 || old->suid == 0) && - (new->uid != 0 && new->euid != 0 && new->suid != 0) && + kuid_t root_uid = make_kuid(old->user_ns, 0); + + if ((uid_eq(old->uid, root_uid) || + uid_eq(old->euid, root_uid) || + uid_eq(old->suid, root_uid)) && + (!uid_eq(new->uid, root_uid) && + !uid_eq(new->euid, root_uid) && + !uid_eq(new->suid, root_uid)) && !issecure(SECURE_KEEP_CAPS)) { cap_clear(new->cap_permitted); cap_clear(new->cap_effective); } - if (old->euid == 0 && new->euid != 0) + if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid)) cap_clear(new->cap_effective); - if (old->euid != 0 && new->euid == 0) + if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid)) new->cap_effective = new->cap_permitted; } @@ -674,11 +737,12 @@ int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags) * if not, we might be a bit too harsh here. */ if (!issecure(SECURE_NO_SETUID_FIXUP)) { - if (old->fsuid == 0 && new->fsuid != 0) + kuid_t root_uid = make_kuid(old->user_ns, 0); + if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid)) new->cap_effective = cap_drop_fs_set(new->cap_effective); - if (old->fsuid != 0 && new->fsuid == 0) + if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid)) new->cap_effective = cap_raise_fs_set(new->cap_effective, new->cap_permitted); @@ -704,16 +768,16 @@ int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags) */ static int cap_safe_nice(struct task_struct *p) { - int is_subset; + int is_subset, ret = 0; rcu_read_lock(); is_subset = cap_issubset(__task_cred(p)->cap_permitted, current_cred()->cap_permitted); + if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) + ret = -EPERM; rcu_read_unlock(); - if (!is_subset && !capable(CAP_SYS_NICE)) - return -EPERM; - return 0; + return ret; } /** @@ -760,7 +824,7 @@ int cap_task_setnice(struct task_struct *p, int nice) */ static long cap_prctl_drop(struct cred *new, unsigned long cap) { - if (!capable(CAP_SETPCAP)) + if (!ns_capable(current_user_ns(), CAP_SETPCAP)) return -EPERM; if (!cap_valid(cap)) return -EINVAL; @@ -830,7 +894,8 @@ int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, & (new->securebits ^ arg2)) /*[1]*/ || ((new->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/ || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/ - || (cap_capable(current, current_cred(), CAP_SETPCAP, + || (cap_capable(current_cred(), + current_cred()->user_ns, CAP_SETPCAP, SECURITY_CAP_AUDIT) != 0) /*[4]*/ /* * [1] no changing of bits that are locked @@ -884,26 +949,6 @@ error: } /** - * cap_syslog - Determine whether syslog function is permitted - * @type: Function requested - * @from_file: Whether this request came from an open file (i.e. /proc) - * - * Determine whether the current process is permitted to use a particular - * syslog function, returning 0 if permission is granted, -ve if not. - */ -int cap_syslog(int type, bool from_file) -{ - if (type != SYSLOG_ACTION_OPEN && from_file) - return 0; - if (dmesg_restrict && !capable(CAP_SYS_ADMIN)) - return -EPERM; - if ((type != SYSLOG_ACTION_READ_ALL && - type != SYSLOG_ACTION_SIZE_BUFFER) && !capable(CAP_SYS_ADMIN)) - return -EPERM; - return 0; -} - -/** * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted * @mm: The VM space in which the new mapping is to be made * @pages: The size of the mapping @@ -915,34 +960,27 @@ int cap_vm_enough_memory(struct mm_struct *mm, long pages) { int cap_sys_admin = 0; - if (cap_capable(current, current_cred(), CAP_SYS_ADMIN, + if (cap_capable(current_cred(), &init_user_ns, CAP_SYS_ADMIN, SECURITY_CAP_NOAUDIT) == 0) cap_sys_admin = 1; return __vm_enough_memory(mm, pages, cap_sys_admin); } /* - * cap_file_mmap - check if able to map given addr - * @file: unused - * @reqprot: unused - * @prot: unused - * @flags: unused + * cap_mmap_addr - check if able to map given addr * @addr: address attempting to be mapped - * @addr_only: unused * * If the process is attempting to map memory below dac_mmap_min_addr they need * CAP_SYS_RAWIO. The other parameters to this function are unused by the * capability security module. Returns 0 if this mapping should be allowed * -EPERM if not. */ -int cap_file_mmap(struct file *file, unsigned long reqprot, - unsigned long prot, unsigned long flags, - unsigned long addr, unsigned long addr_only) +int cap_mmap_addr(unsigned long addr) { int ret = 0; if (addr < dac_mmap_min_addr) { - ret = cap_capable(current, current_cred(), CAP_SYS_RAWIO, + ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO, SECURITY_CAP_AUDIT); /* set PF_SUPERPRIV if it turns out we allow the low mmap */ if (ret == 0) @@ -950,3 +988,9 @@ int cap_file_mmap(struct file *file, unsigned long reqprot, } return ret; } + +int cap_mmap_file(struct file *file, unsigned long reqprot, + unsigned long prot, unsigned long flags) +{ + return 0; +} |