diff options
Diffstat (limited to 'kernel/user_namespace.c')
| -rw-r--r-- | kernel/user_namespace.c | 80 |
1 files changed, 73 insertions, 7 deletions
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index af612945a4d0..ef82d401dde8 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -85,7 +85,7 @@ int create_user_ns(struct cred *new) /* * Verify that we can not violate the policy of which files * may be accessed that is specified by the root directory, - * by verifing that the root directory is at the root of the + * by verifying that the root directory is at the root of the * mount namespace which allows all files to be accessed. */ ret = -EPERM; @@ -106,6 +106,7 @@ int create_user_ns(struct cred *new) if (!ns) goto fail_dec; + ns->parent_could_setfcap = cap_raised(new->cap_effective, CAP_SETFCAP); ret = ns_alloc_inum(&ns->ns); if (ret) goto fail_free; @@ -118,9 +119,13 @@ int create_user_ns(struct cred *new) ns->owner = owner; ns->group = group; INIT_WORK(&ns->work, free_user_ns); - for (i = 0; i < UCOUNT_COUNTS; i++) { + for (i = 0; i < MAX_PER_NAMESPACE_UCOUNTS; i++) { ns->ucount_max[i] = INT_MAX; } + set_rlimit_ucount_max(ns, UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC)); + set_rlimit_ucount_max(ns, UCOUNT_RLIMIT_MSGQUEUE, rlimit(RLIMIT_MSGQUEUE)); + set_rlimit_ucount_max(ns, UCOUNT_RLIMIT_SIGPENDING, rlimit(RLIMIT_SIGPENDING)); + set_rlimit_ucount_max(ns, UCOUNT_RLIMIT_MEMLOCK, rlimit(RLIMIT_MEMLOCK)); ns->ucounts = ucounts; /* Inherit USERNS_SETGROUPS_ALLOWED from our parent */ @@ -841,6 +846,60 @@ static int sort_idmaps(struct uid_gid_map *map) return 0; } +/** + * verify_root_map() - check the uid 0 mapping + * @file: idmapping file + * @map_ns: user namespace of the target process + * @new_map: requested idmap + * + * If a process requests mapping parent uid 0 into the new ns, verify that the + * process writing the map had the CAP_SETFCAP capability as the target process + * will be able to write fscaps that are valid in ancestor user namespaces. + * + * Return: true if the mapping is allowed, false if not. + */ +static bool verify_root_map(const struct file *file, + struct user_namespace *map_ns, + struct uid_gid_map *new_map) +{ + int idx; + const struct user_namespace *file_ns = file->f_cred->user_ns; + struct uid_gid_extent *extent0 = NULL; + + for (idx = 0; idx < new_map->nr_extents; idx++) { + if (new_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) + extent0 = &new_map->extent[idx]; + else + extent0 = &new_map->forward[idx]; + if (extent0->lower_first == 0) + break; + + extent0 = NULL; + } + + if (!extent0) + return true; + + if (map_ns == file_ns) { + /* The process unshared its ns and is writing to its own + * /proc/self/uid_map. User already has full capabilites in + * the new namespace. Verify that the parent had CAP_SETFCAP + * when it unshared. + * */ + if (!file_ns->parent_could_setfcap) + return false; + } else { + /* Process p1 is writing to uid_map of p2, who is in a child + * user namespace to p1's. Verify that the opener of the map + * file has CAP_SETFCAP against the parent of the new map + * namespace */ + if (!file_ns_capable(file, map_ns->parent, CAP_SETFCAP)) + return false; + } + + return true; +} + static ssize_t map_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos, int cap_setid, @@ -848,7 +907,7 @@ static ssize_t map_write(struct file *file, const char __user *buf, struct uid_gid_map *parent_map) { struct seq_file *seq = file->private_data; - struct user_namespace *ns = seq->private; + struct user_namespace *map_ns = seq->private; struct uid_gid_map new_map; unsigned idx; struct uid_gid_extent extent; @@ -895,7 +954,7 @@ static ssize_t map_write(struct file *file, const char __user *buf, /* * Adjusting namespace settings requires capabilities on the target. */ - if (cap_valid(cap_setid) && !file_ns_capable(file, ns, CAP_SYS_ADMIN)) + if (cap_valid(cap_setid) && !file_ns_capable(file, map_ns, CAP_SYS_ADMIN)) goto out; /* Parse the user data */ @@ -959,13 +1018,13 @@ static ssize_t map_write(struct file *file, const char __user *buf, goto out; ret = -EINVAL; } - /* Be very certaint the new map actually exists */ + /* Be very certain the new map actually exists */ if (new_map.nr_extents == 0) goto out; ret = -EPERM; /* Validate the user is allowed to use user id's mapped to. */ - if (!new_idmap_permitted(file, ns, cap_setid, &new_map)) + if (!new_idmap_permitted(file, map_ns, cap_setid, &new_map)) goto out; ret = -EPERM; @@ -1086,6 +1145,10 @@ static bool new_idmap_permitted(const struct file *file, struct uid_gid_map *new_map) { const struct cred *cred = file->f_cred; + + if (cap_setid == CAP_SETUID && !verify_root_map(file, ns, new_map)) + return false; + /* Don't allow mappings that would allow anything that wouldn't * be allowed without the establishment of unprivileged mappings. */ @@ -1110,7 +1173,7 @@ static bool new_idmap_permitted(const struct file *file, /* Allow the specified ids if we have the appropriate capability * (CAP_SETUID or CAP_SETGID) over the parent user namespace. - * And the opener of the id file also had the approprpiate capability. + * And the opener of the id file also has the appropriate capability. */ if (ns_capable(ns->parent, cap_setid) && file_ns_capable(file, ns->parent, cap_setid)) @@ -1281,6 +1344,9 @@ static int userns_install(struct nsset *nsset, struct ns_common *ns) put_user_ns(cred->user_ns); set_cred_user_ns(cred, get_user_ns(user_ns)); + if (set_cred_ucounts(cred) < 0) + return -EINVAL; + return 0; } |