X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=security%2Fcommoncap.c;h=ea61bc73f6d3c4d1ecfe9d81964342b8cd306d74;hb=240d3b54e3a8a8d469f0ff6deacf52f4b751f55a;hp=778cb0cfc5d892fa9ae3f001d35d2560779dd15c;hpb=fb9fc395174138983a49f2da982ed14caabbe741;p=linux-2.6 diff --git a/security/commoncap.c b/security/commoncap.c index 778cb0cfc5..ea61bc73f6 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -23,6 +23,26 @@ #include #include #include +#include + +#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) { @@ -39,6 +59,12 @@ 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. */ @@ -73,14 +99,45 @@ int cap_capget (struct task_struct *target, kernel_cap_t *effective, 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); +} + +#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) { - /* 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; } @@ -140,7 +197,8 @@ 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, +static inline int cap_from_disk(struct vfs_cap_data *caps, + struct linux_binprm *bprm, int size) { __u32 magic_etc; @@ -148,7 +206,7 @@ static inline int cap_from_disk(__le32 *caps, struct linux_binprm *bprm, if (size != XATTR_CAPS_SZ) 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: @@ -156,8 +214,8 @@ static inline int cap_from_disk(__le32 *caps, struct linux_binprm *bprm, 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]) ); + 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; @@ -169,7 +227,7 @@ static int get_file_caps(struct linux_binprm *bprm) { struct dentry *dentry; int rc = 0; - __le32 v1caps[XATTR_CAPS_SZ]; + struct vfs_cap_data incaps; struct inode *inode; if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID) { @@ -182,8 +240,14 @@ 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, 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; @@ -192,7 +256,7 @@ static int get_file_caps(struct linux_binprm *bprm) if (rc < 0) goto out; - rc = cap_from_disk(v1caps, bprm, rc); + 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); @@ -285,7 +349,7 @@ 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)) { + if (!is_global_init(current)) { current->cap_permitted = new_permitted; current->cap_effective = bprm->cap_effective ? new_permitted : 0; @@ -469,6 +533,19 @@ int cap_task_kill(struct task_struct *p, struct siginfo *info, if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info))) return 0; + /* + * Running a setuid root program raises your capabilities. + * Killing your own setuid root processes was previously + * allowed. + * We must preserve legacy signal behavior in this case. + */ + if (p->euid == 0 && p->uid == current->uid) + return 0; + + /* sigcont is permitted within same session */ + if (sig == SIGCONT && (task_session_nr(current) == task_session_nr(p))) + return 0; + if (secid) /* * Signal sent as a particular user.