X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=security%2Fcommoncap.c;h=e4c4b3fc0c04e49e553610a8bd4d433e55e9212a;hb=d8395c876bb8a560c8a032887e191b95499a25d6;hp=afca6dd4ae6900d2c05c230c8119f2558c739e93;hpb=b53767719b6cd8789392ea3e7e2eb7b8906898f0;p=safe%2Fjmp%2Flinux-2.6 diff --git a/security/commoncap.c b/security/commoncap.c index afca6dd..e4c4b3f 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -1,4 +1,4 @@ -/* Common capabilities, needed by capability.o and root_plug.o +/* 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 @@ -23,6 +23,9 @@ #include #include #include +#include +#include +#include int cap_netlink_send(struct sock *sk, struct sk_buff *skb) { @@ -30,8 +33,6 @@ int cap_netlink_send(struct sock *sk, struct sk_buff *skb) return 0; } -EXPORT_SYMBOL(cap_netlink_send); - int cap_netlink_recv(struct sk_buff *skb, int cap) { if (!cap_raised(NETLINK_CB(skb).eff_cap, cap)) @@ -41,6 +42,12 @@ int cap_netlink_recv(struct sk_buff *skb, int cap) EXPORT_SYMBOL(cap_netlink_recv); +/* + * NOTE WELL: cap_capable() cannot be used like the kernel's capable() + * function. That is, it has the reverse semantics: cap_capable() + * returns 0 when a task has a capability, but the kernel's capable() + * returns 1 for this case. + */ int cap_capable (struct task_struct *tsk, int cap) { /* Derived from include/linux/sched.h:capable. */ @@ -56,33 +63,87 @@ int cap_settime(struct timespec *ts, struct timezone *tz) return 0; } -int cap_ptrace (struct task_struct *parent, struct task_struct *child) +int cap_ptrace_may_access(struct task_struct *child, unsigned int mode) { /* 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; + if (cap_issubset(child->cap_permitted, current->cap_permitted)) + return 0; + if (capable(CAP_SYS_PTRACE)) + return 0; + return -EPERM; +} + +int cap_ptrace_traceme(struct task_struct *parent) +{ + /* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */ + if (cap_issubset(current->cap_permitted, parent->cap_permitted)) + return 0; + if (has_capability(parent, CAP_SYS_PTRACE)) + return 0; + return -EPERM; } 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); + *effective = target->cap_effective; + *inheritable = target->cap_inheritable; + *permitted = 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. That is, if the current task + * does *not* possess the CAP_SETPCAP capability. + */ + return (cap_capable(current, CAP_SETPCAP) != 0); +} + +static inline int cap_limit_ptraced_target(void) { return 1; } + +#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; } +static inline int cap_limit_ptraced_target(void) +{ + return !capable(CAP_SETPCAP); +} + +#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) { - /* 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))) { + 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; + } + if (!cap_issubset(*inheritable, + cap_combine(target->cap_inheritable, + current->cap_bset))) { + /* no new pI capabilities outside bounding set */ return -EPERM; } @@ -111,8 +172,7 @@ void cap_capset_set (struct task_struct *target, kernel_cap_t *effective, static inline void bprm_clear_caps(struct linux_binprm *bprm) { - cap_clear(bprm->cap_inheritable); - cap_clear(bprm->cap_permitted); + cap_clear(bprm->cap_post_exec_permitted); bprm->cap_effective = false; } @@ -142,28 +202,73 @@ int cap_inode_killpriv(struct dentry *dentry) return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS); } -static inline int cap_from_disk(__le32 *caps, struct linux_binprm *bprm, - int size) +static inline int cap_from_disk(struct vfs_cap_data *caps, + struct linux_binprm *bprm, unsigned size) { __u32 magic_etc; + unsigned tocopy, i; + int ret; - if (size != XATTR_CAPS_SZ) + if (size < sizeof(magic_etc)) return -EINVAL; - magic_etc = le32_to_cpu(caps[0]); + 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[1]) ); - bprm->cap_inheritable = to_cap_t( le32_to_cpu(caps[2]) ); - return 0; + case VFS_CAP_REVISION_1: + if (size != XATTR_CAPS_SZ_1) + return -EINVAL; + tocopy = VFS_CAP_U32_1; + break; + case VFS_CAP_REVISION_2: + if (size != XATTR_CAPS_SZ_2) + return -EINVAL; + tocopy = VFS_CAP_U32_2; + break; default: return -EINVAL; } + + if (magic_etc & VFS_CAP_FLAGS_EFFECTIVE) { + bprm->cap_effective = true; + } else { + bprm->cap_effective = false; + } + + ret = 0; + + CAP_FOR_EACH_U32(i) { + __u32 value_cpu; + + if (i >= tocopy) { + /* + * Legacy capability sets have no upper bits + */ + bprm->cap_post_exec_permitted.cap[i] = 0; + continue; + } + /* + * pP' = (X & fP) | (pI & fI) + */ + value_cpu = le32_to_cpu(caps->data[i].permitted); + bprm->cap_post_exec_permitted.cap[i] = + (current->cap_bset.cap[i] & value_cpu) | + (current->cap_inheritable.cap[i] & + le32_to_cpu(caps->data[i].inheritable)); + if (value_cpu & ~bprm->cap_post_exec_permitted.cap[i]) { + /* + * insufficient to execute correctly + */ + ret = -EPERM; + } + } + + /* + * For legacy apps, with no internal support for recognizing they + * do not have enough capabilities, we return an error if they are + * missing some "forced" (aka file-permitted) capabilities. + */ + return bprm->cap_effective ? ret : 0; } /* Locate any VFS capabilities: */ @@ -171,7 +276,7 @@ static int get_file_caps(struct linux_binprm *bprm) { struct dentry *dentry; int rc = 0; - __le32 v1caps[XATTR_CAPS_SZ]; + struct vfs_cap_data vcaps; struct inode *inode; if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID) { @@ -184,8 +289,8 @@ static int get_file_caps(struct linux_binprm *bprm) if (!inode->i_op || !inode->i_op->getxattr) goto out; - rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, &v1caps, - XATTR_CAPS_SZ); + rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, &vcaps, + XATTR_CAPS_SZ); if (rc == -ENODATA || rc == -EOPNOTSUPP) { /* no data, that's ok */ rc = 0; @@ -194,10 +299,10 @@ static int get_file_caps(struct linux_binprm *bprm) if (rc < 0) goto out; - rc = cap_from_disk(v1caps, bprm, rc); - if (rc) + rc = cap_from_disk(&vcaps, bprm, rc); + if (rc == -EINVAL) printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n", - __FUNCTION__, rc, bprm->filename); + __func__, rc, bprm->filename); out: dput(dentry); @@ -230,25 +335,24 @@ 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 (!issecure(SECURE_NOROOT)) { + /* + * To support inheritance of root-permissions and suid-root + * executables under compatibility mode, we override the + * capability sets for the file. + * + * If only the real uid is 0, we do not set the effective + * bit. + */ if (bprm->e_uid == 0 || current->uid == 0) { - cap_set_full (bprm->cap_inheritable); - cap_set_full (bprm->cap_permitted); + /* pP' = (cap_bset & ~0) | (pI & ~0) */ + bprm->cap_post_exec_permitted = cap_combine( + current->cap_bset, current->cap_inheritable + ); + bprm->cap_effective = (bprm->e_uid == 0); + ret = 0; } - if (bprm->e_uid == 0) - bprm->cap_effective = true; } return ret; @@ -256,16 +360,9 @@ int cap_bprm_set_security (struct linux_binprm *bprm) 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)) { + !cap_issubset(bprm->cap_post_exec_permitted, + current->cap_permitted)) { set_dumpable(current->mm, suid_dumpable); current->pdeath_signal = 0; @@ -274,9 +371,10 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe) bprm->e_uid = current->uid; bprm->e_gid = current->gid; } - if (!capable (CAP_SETPCAP)) { - new_permitted = cap_intersect (new_permitted, - current->cap_permitted); + if (cap_limit_ptraced_target()) { + bprm->cap_post_exec_permitted = cap_intersect( + bprm->cap_post_exec_permitted, + current->cap_permitted); } } } @@ -287,15 +385,17 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe) /* For init, we want to retain the capabilities set * in the init_task struct. Thus we skip the usual * capability rules */ - if (!is_init(current)) { - current->cap_permitted = new_permitted; - current->cap_effective = bprm->cap_effective ? - new_permitted : 0; + if (!is_global_init(current)) { + current->cap_permitted = bprm->cap_post_exec_permitted; + if (bprm->cap_effective) + current->cap_effective = bprm->cap_post_exec_permitted; + else + cap_clear(current->cap_effective); } /* 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) @@ -303,9 +403,7 @@ 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)) + if (!cap_isclear(bprm->cap_post_exec_permitted)) return 1; } @@ -313,8 +411,8 @@ int cap_bprm_secureexec (struct linux_binprm *bprm) current->egid != current->gid); } -int cap_inode_setxattr(struct dentry *dentry, char *name, void *value, - size_t size, int flags) +int cap_inode_setxattr(struct dentry *dentry, const char *name, + const void *value, size_t size, int flags) { if (!strcmp(name, XATTR_NAME_CAPS)) { if (!capable(CAP_SETFCAP)) @@ -327,7 +425,7 @@ int cap_inode_setxattr(struct dentry *dentry, char *name, void *value, return 0; } -int cap_inode_removexattr(struct dentry *dentry, char *name) +int cap_inode_removexattr(struct dentry *dentry, const char *name) { if (!strcmp(name, XATTR_NAME_CAPS)) { if (!capable(CAP_SETFCAP)) @@ -375,7 +473,7 @@ 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); } @@ -412,13 +510,15 @@ int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid, if (!issecure (SECURE_NO_SETUID_FIXUP)) { if (old_fsuid == 0 && current->fsuid != 0) { - cap_t (current->cap_effective) &= - ~CAP_FS_MASK; + current->cap_effective = + cap_drop_fs_set( + current->cap_effective); } if (old_fsuid != 0 && current->fsuid == 0) { - cap_t (current->cap_effective) |= - (cap_t (current->cap_permitted) & - CAP_FS_MASK); + current->cap_effective = + cap_raise_fs_set( + current->cap_effective, + current->cap_permitted); } } break; @@ -444,7 +544,7 @@ int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid, static inline int cap_safe_nice(struct task_struct *p) { if (!cap_issubset(p->cap_permitted, current->cap_permitted) && - !__capable(current, CAP_SYS_NICE)) + !capable(CAP_SYS_NICE)) return -EPERM; return 0; } @@ -465,27 +565,23 @@ 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) +/* + * 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. + */ +static long cap_prctl_drop(unsigned long cap) { - 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; + 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) @@ -500,19 +596,101 @@ 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) +#endif + +int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, + unsigned long arg4, unsigned long arg5, long *rc_p) { - return 0; + 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; } -#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; + cap_set_init_eff(p->cap_effective); + cap_clear(p->cap_inheritable); + cap_set_full(p->cap_permitted); + p->securebits = SECUREBITS_DEFAULT; return; } @@ -532,22 +710,3 @@ int cap_vm_enough_memory(struct mm_struct *mm, long pages) return __vm_enough_memory(mm, 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_kill); -EXPORT_SYMBOL(cap_task_setscheduler); -EXPORT_SYMBOL(cap_task_setioprio); -EXPORT_SYMBOL(cap_task_setnice); -EXPORT_SYMBOL(cap_task_reparent_to_init); -EXPORT_SYMBOL(cap_syslog); -EXPORT_SYMBOL(cap_vm_enough_memory);