diff options
Diffstat (limited to 'security/commoncap.c')
| -rw-r--r-- | security/commoncap.c | 244 |
1 files changed, 228 insertions, 16 deletions
diff --git a/security/commoncap.c b/security/commoncap.c index 0f8a2ce3f3a6..afca6dd4ae69 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -22,6 +22,7 @@ #include <linux/ptrace.h> #include <linux/xattr.h> #include <linux/hugetlb.h> +#include <linux/mount.h> int cap_netlink_send(struct sock *sk, struct sk_buff *skb) { @@ -108,14 +109,130 @@ void cap_capset_set (struct task_struct *target, kernel_cap_t *effective, 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(__le32 *caps, struct linux_binprm *bprm, + int size) +{ + __u32 magic_etc; + + if (size != XATTR_CAPS_SZ) + return -EINVAL; + + magic_etc = le32_to_cpu(caps[0]); + + 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; + default: + return -EINVAL; + } +} + +/* Locate any VFS capabilities: */ +static int get_file_caps(struct linux_binprm *bprm) +{ + struct dentry *dentry; + int rc = 0; + __le32 v1caps[XATTR_CAPS_SZ]; + 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, &v1caps, + XATTR_CAPS_SZ); + if (rc == -ENODATA || rc == -EOPNOTSUPP) { + /* no data, that's ok */ + rc = 0; + goto out; + } + if (rc < 0) + goto out; + + rc = cap_from_disk(v1caps, 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) { - /* Copied from fs/exec.c:prepare_binprm. */ + int ret; - /* We don't have VFS support for capabilities yet */ - cap_clear (bprm->cap_inheritable); - cap_clear (bprm->cap_permitted); - cap_clear (bprm->cap_effective); + 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 @@ -131,9 +248,10 @@ int cap_bprm_set_security (struct linux_binprm *bprm) cap_set_full (bprm->cap_permitted); } if (bprm->e_uid == 0) - cap_set_full (bprm->cap_effective); + bprm->cap_effective = true; } - return 0; + + return ret; } void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe) @@ -149,6 +267,7 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe) 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)) { @@ -170,8 +289,8 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe) * capability rules */ if (!is_init(current)) { current->cap_permitted = new_permitted; - current->cap_effective = - cap_intersect (new_permitted, bprm->cap_effective); + current->cap_effective = bprm->cap_effective ? + new_permitted : 0; } /* AUD: Audit candidate if current->cap_effective is set */ @@ -181,11 +300,15 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe) 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. */ + 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); } @@ -193,7 +316,11 @@ int cap_bprm_secureexec (struct linux_binprm *bprm) int cap_inode_setxattr(struct dentry *dentry, char *name, void *value, size_t size, int flags) { - if (!strncmp(name, XATTR_SECURITY_PREFIX, + 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; @@ -202,7 +329,11 @@ int cap_inode_setxattr(struct dentry *dentry, char *name, void *value, int cap_inode_removexattr(struct dentry *dentry, char *name) { - if (!strncmp(name, XATTR_SECURITY_PREFIX, + 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; @@ -299,6 +430,83 @@ int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid, 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; @@ -336,6 +544,10 @@ 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); |