diff options
Diffstat (limited to 'security/commoncap.c')
| -rw-r--r-- | security/commoncap.c | 108 |
1 files changed, 88 insertions, 20 deletions
diff --git a/security/commoncap.c b/security/commoncap.c index 78598be45f10..28f4d25480df 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -303,17 +303,25 @@ int cap_inode_need_killpriv(struct dentry *dentry) /** * cap_inode_killpriv - Erase the security markings on an inode - * @dentry: The inode/dentry to alter + * + * @mnt_userns: user namespace of the mount the inode was found from + * @dentry: The inode/dentry to alter * * Erase the privilege-enhancing security markings on an inode. * + * If the inode has been found through an idmapped mount the user namespace of + * the vfsmount must be passed through @mnt_userns. This function will then + * take care to map the inode according to @mnt_userns before checking + * permissions. On non-idmapped mounts or if permission checking is to be + * performed on the raw inode simply passs init_user_ns. + * * Returns 0 if successful, -ve on error. */ -int cap_inode_killpriv(struct dentry *dentry) +int cap_inode_killpriv(struct user_namespace *mnt_userns, struct dentry *dentry) { int error; - error = __vfs_removexattr(dentry, XATTR_NAME_CAPS); + error = __vfs_removexattr(mnt_userns, dentry, XATTR_NAME_CAPS); if (error == -EOPNOTSUPP) error = 0; return error; @@ -366,7 +374,8 @@ static bool is_v3header(size_t size, const struct vfs_cap_data *cap) * by the integrity subsystem, which really wants the unconverted values - * so that's good. */ -int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer, +int cap_inode_getsecurity(struct user_namespace *mnt_userns, + struct inode *inode, const char *name, void **buffer, bool alloc) { int size, ret; @@ -387,8 +396,8 @@ int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer, return -EINVAL; size = sizeof(struct vfs_ns_cap_data); - ret = (int) vfs_getxattr_alloc(dentry, XATTR_NAME_CAPS, - &tmpbuf, size, GFP_NOFS); + ret = (int)vfs_getxattr_alloc(mnt_userns, dentry, XATTR_NAME_CAPS, + &tmpbuf, size, GFP_NOFS); dput(dentry); if (ret < 0) @@ -408,6 +417,9 @@ int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer, kroot = make_kuid(fs_ns, root); + /* If this is an idmapped mount shift the kuid. */ + kroot = kuid_into_mnt(mnt_userns, kroot); + /* If the root kuid maps to a valid uid in current ns, then return * this as a nscap. */ mappedroot = from_kuid(current_user_ns(), kroot); @@ -469,16 +481,33 @@ out_free: return size; } +/** + * rootid_from_xattr - translate root uid of vfs caps + * + * @value: vfs caps value which may be modified by this function + * @size: size of @ivalue + * @task_ns: user namespace of the caller + * @mnt_userns: user namespace of the mount the inode was found from + * + * If the inode has been found through an idmapped mount the user namespace of + * the vfsmount must be passed through @mnt_userns. This function will then + * take care to map the inode according to @mnt_userns before checking + * permissions. On non-idmapped mounts or if permission checking is to be + * performed on the raw inode simply passs init_user_ns. + */ static kuid_t rootid_from_xattr(const void *value, size_t size, - struct user_namespace *task_ns) + struct user_namespace *task_ns, + struct user_namespace *mnt_userns) { const struct vfs_ns_cap_data *nscap = value; + kuid_t rootkid; uid_t rootid = 0; if (size == XATTR_CAPS_SZ_3) rootid = le32_to_cpu(nscap->rootid); - return make_kuid(task_ns, rootid); + rootkid = make_kuid(task_ns, rootid); + return kuid_from_mnt(mnt_userns, rootkid); } static bool validheader(size_t size, const struct vfs_cap_data *cap) @@ -486,13 +515,27 @@ static bool validheader(size_t size, const struct vfs_cap_data *cap) return is_v2header(size, cap) || is_v3header(size, cap); } -/* +/** + * cap_convert_nscap - check vfs caps + * + * @mnt_userns: user namespace of the mount the inode was found from + * @dentry: used to retrieve inode to check permissions on + * @ivalue: vfs caps value which may be modified by this function + * @size: size of @ivalue + * * User requested a write of security.capability. If needed, update the * xattr to change from v2 to v3, or to fixup the v3 rootid. * + * If the inode has been found through an idmapped mount the user namespace of + * the vfsmount must be passed through @mnt_userns. This function will then + * take care to map the inode according to @mnt_userns before checking + * permissions. On non-idmapped mounts or if permission checking is to be + * performed on the raw inode simply passs init_user_ns. + * * If all is ok, we return the new size, on error return < 0. */ -int cap_convert_nscap(struct dentry *dentry, const void **ivalue, size_t size) +int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry, + const void **ivalue, size_t size) { struct vfs_ns_cap_data *nscap; uid_t nsrootid; @@ -509,14 +552,14 @@ int cap_convert_nscap(struct dentry *dentry, const void **ivalue, size_t size) return -EINVAL; if (!validheader(size, cap)) return -EINVAL; - if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP)) + if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP)) return -EPERM; - if (size == XATTR_CAPS_SZ_2) + if (size == XATTR_CAPS_SZ_2 && (mnt_userns == &init_user_ns)) if (ns_capable(inode->i_sb->s_user_ns, CAP_SETFCAP)) /* user is privileged, just write the v2 */ return size; - rootid = rootid_from_xattr(*ivalue, size, task_ns); + rootid = rootid_from_xattr(*ivalue, size, task_ns, mnt_userns); if (!uid_valid(rootid)) return -EINVAL; @@ -593,10 +636,24 @@ static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps, return *effective ? ret : 0; } -/* +/** + * get_vfs_caps_from_disk - retrieve vfs caps from disk + * + * @mnt_userns: user namespace of the mount the inode was found from + * @dentry: dentry from which @inode is retrieved + * @cpu_caps: vfs capabilities + * * Extract the on-exec-apply capability sets for an executable file. + * + * If the inode has been found through an idmapped mount the user namespace of + * the vfsmount must be passed through @mnt_userns. This function will then + * take care to map the inode according to @mnt_userns before checking + * permissions. On non-idmapped mounts or if permission checking is to be + * performed on the raw inode simply passs init_user_ns. */ -int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps) +int get_vfs_caps_from_disk(struct user_namespace *mnt_userns, + const struct dentry *dentry, + struct cpu_vfs_cap_data *cpu_caps) { struct inode *inode = d_backing_inode(dentry); __u32 magic_etc; @@ -652,6 +709,7 @@ int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data /* Limit the caps to the mounter of the filesystem * or the more limited uid specified in the xattr. */ + rootkuid = kuid_into_mnt(mnt_userns, rootkuid); if (!rootid_owns_currentns(rootkuid)) return -ENODATA; @@ -697,7 +755,8 @@ static int get_file_caps(struct linux_binprm *bprm, struct file *file, if (!current_in_userns(file->f_path.mnt->mnt_sb->s_user_ns)) return 0; - rc = get_vfs_caps_from_disk(file->f_path.dentry, &vcaps); + rc = get_vfs_caps_from_disk(file_mnt_user_ns(file), + file->f_path.dentry, &vcaps); if (rc < 0) { if (rc == -EINVAL) printk(KERN_NOTICE "Invalid argument reading file caps for %s\n", @@ -962,16 +1021,25 @@ int cap_inode_setxattr(struct dentry *dentry, const char *name, /** * cap_inode_removexattr - Determine whether an xattr may be removed - * @dentry: The inode/dentry being altered - * @name: The name of the xattr to be changed + * + * @mnt_userns: User namespace of the mount the inode was found from + * @dentry: The inode/dentry being altered + * @name: The name of the xattr to be changed * * Determine whether an xattr may be removed from an inode, returning 0 if * permission is granted, -ve if denied. * + * If the inode has been found through an idmapped mount the user namespace of + * the vfsmount must be passed through @mnt_userns. This function will then + * take care to map the inode according to @mnt_userns before checking + * permissions. On non-idmapped mounts or if permission checking is to be + * performed on the raw inode simply passs init_user_ns. + * * This is used to make sure security xattrs don't get removed by those who * aren't privileged to remove them. */ -int cap_inode_removexattr(struct dentry *dentry, const char *name) +int cap_inode_removexattr(struct user_namespace *mnt_userns, + struct dentry *dentry, const char *name) { struct user_namespace *user_ns = dentry->d_sb->s_user_ns; @@ -985,7 +1053,7 @@ int cap_inode_removexattr(struct dentry *dentry, const char *name) struct inode *inode = d_backing_inode(dentry); if (!inode) return -EINVAL; - if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP)) + if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP)) return -EPERM; return 0; } |