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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 11:19:37 +00:00
![Kees Cook](/assets/img/avatar_default.png)
The kmalloc() function has a 2-factor argument form, kmalloc_array(). This patch replaces cases of: kmalloc(a * b, gfp) with: kmalloc_array(a * b, gfp) as well as handling cases of: kmalloc(a * b * c, gfp) with: kmalloc(array3_size(a, b, c), gfp) as it's slightly less ugly than: kmalloc_array(array_size(a, b), c, gfp) This does, however, attempt to ignore constant size factors like: kmalloc(4 * 1024, gfp) though any constants defined via macros get caught up in the conversion. Any factors with a sizeof() of "unsigned char", "char", and "u8" were dropped, since they're redundant. The tools/ directory was manually excluded, since it has its own implementation of kmalloc(). The Coccinelle script used for this was: // Fix redundant parens around sizeof(). @@ type TYPE; expression THING, E; @@ ( kmalloc( - (sizeof(TYPE)) * E + sizeof(TYPE) * E , ...) | kmalloc( - (sizeof(THING)) * E + sizeof(THING) * E , ...) ) // Drop single-byte sizes and redundant parens. @@ expression COUNT; typedef u8; typedef __u8; @@ ( kmalloc( - sizeof(u8) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(__u8) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(char) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(unsigned char) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(u8) * COUNT + COUNT , ...) | kmalloc( - sizeof(__u8) * COUNT + COUNT , ...) | kmalloc( - sizeof(char) * COUNT + COUNT , ...) | kmalloc( - sizeof(unsigned char) * COUNT + COUNT , ...) ) // 2-factor product with sizeof(type/expression) and identifier or constant. @@ type TYPE; expression THING; identifier COUNT_ID; constant COUNT_CONST; @@ ( - kmalloc + kmalloc_array ( - sizeof(TYPE) * (COUNT_ID) + COUNT_ID, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * COUNT_ID + COUNT_ID, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * (COUNT_CONST) + COUNT_CONST, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * COUNT_CONST + COUNT_CONST, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * (COUNT_ID) + COUNT_ID, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * COUNT_ID + COUNT_ID, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * (COUNT_CONST) + COUNT_CONST, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * COUNT_CONST + COUNT_CONST, sizeof(THING) , ...) ) // 2-factor product, only identifiers. @@ identifier SIZE, COUNT; @@ - kmalloc + kmalloc_array ( - SIZE * COUNT + COUNT, SIZE , ...) // 3-factor product with 1 sizeof(type) or sizeof(expression), with // redundant parens removed. @@ expression THING; identifier STRIDE, COUNT; type TYPE; @@ ( kmalloc( - sizeof(TYPE) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(TYPE) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(TYPE) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(TYPE) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(THING) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kmalloc( - sizeof(THING) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kmalloc( - sizeof(THING) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kmalloc( - sizeof(THING) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) ) // 3-factor product with 2 sizeof(variable), with redundant parens removed. @@ expression THING1, THING2; identifier COUNT; type TYPE1, TYPE2; @@ ( kmalloc( - sizeof(TYPE1) * sizeof(TYPE2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kmalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kmalloc( - sizeof(THING1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kmalloc( - sizeof(THING1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kmalloc( - sizeof(TYPE1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) | kmalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) ) // 3-factor product, only identifiers, with redundant parens removed. @@ identifier STRIDE, SIZE, COUNT; @@ ( kmalloc( - (COUNT) * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - (COUNT) * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - (COUNT) * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - (COUNT) * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) ) // Any remaining multi-factor products, first at least 3-factor products, // when they're not all constants... @@ expression E1, E2, E3; constant C1, C2, C3; @@ ( kmalloc(C1 * C2 * C3, ...) | kmalloc( - (E1) * E2 * E3 + array3_size(E1, E2, E3) , ...) | kmalloc( - (E1) * (E2) * E3 + array3_size(E1, E2, E3) , ...) | kmalloc( - (E1) * (E2) * (E3) + array3_size(E1, E2, E3) , ...) | kmalloc( - E1 * E2 * E3 + array3_size(E1, E2, E3) , ...) ) // And then all remaining 2 factors products when they're not all constants, // keeping sizeof() as the second factor argument. @@ expression THING, E1, E2; type TYPE; constant C1, C2, C3; @@ ( kmalloc(sizeof(THING) * C2, ...) | kmalloc(sizeof(TYPE) * C2, ...) | kmalloc(C1 * C2 * C3, ...) | kmalloc(C1 * C2, ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * (E2) + E2, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * E2 + E2, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * (E2) + E2, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * E2 + E2, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - (E1) * E2 + E1, E2 , ...) | - kmalloc + kmalloc_array ( - (E1) * (E2) + E1, E2 , ...) | - kmalloc + kmalloc_array ( - E1 * E2 + E1, E2 , ...) ) Signed-off-by: Kees Cook <keescook@chromium.org>
1331 lines
33 KiB
C
1331 lines
33 KiB
C
/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*/
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#include <linux/export.h>
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#include <linux/nsproxy.h>
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#include <linux/slab.h>
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#include <linux/sched/signal.h>
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#include <linux/user_namespace.h>
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#include <linux/proc_ns.h>
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#include <linux/highuid.h>
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#include <linux/cred.h>
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#include <linux/securebits.h>
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#include <linux/keyctl.h>
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#include <linux/key-type.h>
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#include <keys/user-type.h>
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#include <linux/seq_file.h>
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#include <linux/fs.h>
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#include <linux/uaccess.h>
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#include <linux/ctype.h>
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#include <linux/projid.h>
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#include <linux/fs_struct.h>
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#include <linux/bsearch.h>
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#include <linux/sort.h>
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static struct kmem_cache *user_ns_cachep __read_mostly;
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static DEFINE_MUTEX(userns_state_mutex);
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static bool new_idmap_permitted(const struct file *file,
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struct user_namespace *ns, int cap_setid,
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struct uid_gid_map *map);
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static void free_user_ns(struct work_struct *work);
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static struct ucounts *inc_user_namespaces(struct user_namespace *ns, kuid_t uid)
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{
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return inc_ucount(ns, uid, UCOUNT_USER_NAMESPACES);
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}
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static void dec_user_namespaces(struct ucounts *ucounts)
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{
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return dec_ucount(ucounts, UCOUNT_USER_NAMESPACES);
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}
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static void set_cred_user_ns(struct cred *cred, struct user_namespace *user_ns)
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{
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/* Start with the same capabilities as init but useless for doing
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* anything as the capabilities are bound to the new user namespace.
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*/
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cred->securebits = SECUREBITS_DEFAULT;
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cred->cap_inheritable = CAP_EMPTY_SET;
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cred->cap_permitted = CAP_FULL_SET;
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cred->cap_effective = CAP_FULL_SET;
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cred->cap_ambient = CAP_EMPTY_SET;
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cred->cap_bset = CAP_FULL_SET;
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#ifdef CONFIG_KEYS
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key_put(cred->request_key_auth);
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cred->request_key_auth = NULL;
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#endif
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/* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */
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cred->user_ns = user_ns;
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}
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/*
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* Create a new user namespace, deriving the creator from the user in the
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* passed credentials, and replacing that user with the new root user for the
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* new namespace.
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*
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* This is called by copy_creds(), which will finish setting the target task's
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* credentials.
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*/
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int create_user_ns(struct cred *new)
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{
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struct user_namespace *ns, *parent_ns = new->user_ns;
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kuid_t owner = new->euid;
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kgid_t group = new->egid;
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struct ucounts *ucounts;
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int ret, i;
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ret = -ENOSPC;
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if (parent_ns->level > 32)
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goto fail;
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ucounts = inc_user_namespaces(parent_ns, owner);
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if (!ucounts)
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goto fail;
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/*
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* Verify that we can not violate the policy of which files
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* may be accessed that is specified by the root directory,
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* by verifing that the root directory is at the root of the
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* mount namespace which allows all files to be accessed.
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*/
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ret = -EPERM;
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if (current_chrooted())
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goto fail_dec;
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/* The creator needs a mapping in the parent user namespace
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* or else we won't be able to reasonably tell userspace who
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* created a user_namespace.
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*/
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ret = -EPERM;
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if (!kuid_has_mapping(parent_ns, owner) ||
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!kgid_has_mapping(parent_ns, group))
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goto fail_dec;
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ret = -ENOMEM;
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ns = kmem_cache_zalloc(user_ns_cachep, GFP_KERNEL);
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if (!ns)
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goto fail_dec;
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ret = ns_alloc_inum(&ns->ns);
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if (ret)
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goto fail_free;
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ns->ns.ops = &userns_operations;
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atomic_set(&ns->count, 1);
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/* Leave the new->user_ns reference with the new user namespace. */
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ns->parent = parent_ns;
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ns->level = parent_ns->level + 1;
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ns->owner = owner;
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ns->group = group;
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INIT_WORK(&ns->work, free_user_ns);
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for (i = 0; i < UCOUNT_COUNTS; i++) {
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ns->ucount_max[i] = INT_MAX;
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}
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ns->ucounts = ucounts;
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/* Inherit USERNS_SETGROUPS_ALLOWED from our parent */
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mutex_lock(&userns_state_mutex);
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ns->flags = parent_ns->flags;
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mutex_unlock(&userns_state_mutex);
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#ifdef CONFIG_PERSISTENT_KEYRINGS
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init_rwsem(&ns->persistent_keyring_register_sem);
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#endif
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ret = -ENOMEM;
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if (!setup_userns_sysctls(ns))
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goto fail_keyring;
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set_cred_user_ns(new, ns);
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return 0;
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fail_keyring:
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#ifdef CONFIG_PERSISTENT_KEYRINGS
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key_put(ns->persistent_keyring_register);
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#endif
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ns_free_inum(&ns->ns);
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fail_free:
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kmem_cache_free(user_ns_cachep, ns);
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fail_dec:
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dec_user_namespaces(ucounts);
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fail:
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return ret;
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}
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int unshare_userns(unsigned long unshare_flags, struct cred **new_cred)
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{
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struct cred *cred;
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int err = -ENOMEM;
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if (!(unshare_flags & CLONE_NEWUSER))
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return 0;
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cred = prepare_creds();
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if (cred) {
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err = create_user_ns(cred);
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if (err)
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put_cred(cred);
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else
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*new_cred = cred;
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}
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return err;
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}
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static void free_user_ns(struct work_struct *work)
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{
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struct user_namespace *parent, *ns =
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container_of(work, struct user_namespace, work);
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do {
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struct ucounts *ucounts = ns->ucounts;
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parent = ns->parent;
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if (ns->gid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) {
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kfree(ns->gid_map.forward);
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kfree(ns->gid_map.reverse);
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}
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if (ns->uid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) {
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kfree(ns->uid_map.forward);
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kfree(ns->uid_map.reverse);
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}
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if (ns->projid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) {
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kfree(ns->projid_map.forward);
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kfree(ns->projid_map.reverse);
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}
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retire_userns_sysctls(ns);
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#ifdef CONFIG_PERSISTENT_KEYRINGS
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key_put(ns->persistent_keyring_register);
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#endif
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ns_free_inum(&ns->ns);
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kmem_cache_free(user_ns_cachep, ns);
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dec_user_namespaces(ucounts);
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ns = parent;
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} while (atomic_dec_and_test(&parent->count));
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}
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void __put_user_ns(struct user_namespace *ns)
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{
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schedule_work(&ns->work);
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}
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EXPORT_SYMBOL(__put_user_ns);
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/**
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* idmap_key struct holds the information necessary to find an idmapping in a
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* sorted idmap array. It is passed to cmp_map_id() as first argument.
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*/
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struct idmap_key {
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bool map_up; /* true -> id from kid; false -> kid from id */
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u32 id; /* id to find */
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u32 count; /* == 0 unless used with map_id_range_down() */
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};
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/**
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* cmp_map_id - Function to be passed to bsearch() to find the requested
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* idmapping. Expects struct idmap_key to be passed via @k.
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*/
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static int cmp_map_id(const void *k, const void *e)
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{
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u32 first, last, id2;
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const struct idmap_key *key = k;
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const struct uid_gid_extent *el = e;
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id2 = key->id + key->count - 1;
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/* handle map_id_{down,up}() */
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if (key->map_up)
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first = el->lower_first;
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else
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first = el->first;
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last = first + el->count - 1;
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if (key->id >= first && key->id <= last &&
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(id2 >= first && id2 <= last))
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return 0;
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if (key->id < first || id2 < first)
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return -1;
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return 1;
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}
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/**
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* map_id_range_down_max - Find idmap via binary search in ordered idmap array.
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* Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS.
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*/
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static struct uid_gid_extent *
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map_id_range_down_max(unsigned extents, struct uid_gid_map *map, u32 id, u32 count)
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{
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struct idmap_key key;
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key.map_up = false;
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key.count = count;
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key.id = id;
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return bsearch(&key, map->forward, extents,
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sizeof(struct uid_gid_extent), cmp_map_id);
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}
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/**
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* map_id_range_down_base - Find idmap via binary search in static extent array.
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* Can only be called if number of mappings is equal or less than
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* UID_GID_MAP_MAX_BASE_EXTENTS.
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*/
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static struct uid_gid_extent *
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map_id_range_down_base(unsigned extents, struct uid_gid_map *map, u32 id, u32 count)
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{
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unsigned idx;
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u32 first, last, id2;
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id2 = id + count - 1;
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/* Find the matching extent */
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for (idx = 0; idx < extents; idx++) {
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first = map->extent[idx].first;
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last = first + map->extent[idx].count - 1;
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if (id >= first && id <= last &&
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(id2 >= first && id2 <= last))
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return &map->extent[idx];
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}
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return NULL;
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}
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static u32 map_id_range_down(struct uid_gid_map *map, u32 id, u32 count)
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{
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struct uid_gid_extent *extent;
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unsigned extents = map->nr_extents;
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smp_rmb();
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if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
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extent = map_id_range_down_base(extents, map, id, count);
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else
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extent = map_id_range_down_max(extents, map, id, count);
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/* Map the id or note failure */
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if (extent)
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id = (id - extent->first) + extent->lower_first;
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else
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id = (u32) -1;
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return id;
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}
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static u32 map_id_down(struct uid_gid_map *map, u32 id)
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{
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return map_id_range_down(map, id, 1);
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}
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/**
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* map_id_up_base - Find idmap via binary search in static extent array.
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* Can only be called if number of mappings is equal or less than
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* UID_GID_MAP_MAX_BASE_EXTENTS.
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*/
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static struct uid_gid_extent *
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map_id_up_base(unsigned extents, struct uid_gid_map *map, u32 id)
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{
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unsigned idx;
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u32 first, last;
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/* Find the matching extent */
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for (idx = 0; idx < extents; idx++) {
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first = map->extent[idx].lower_first;
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last = first + map->extent[idx].count - 1;
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if (id >= first && id <= last)
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return &map->extent[idx];
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}
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return NULL;
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}
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/**
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* map_id_up_max - Find idmap via binary search in ordered idmap array.
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* Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS.
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*/
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static struct uid_gid_extent *
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map_id_up_max(unsigned extents, struct uid_gid_map *map, u32 id)
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{
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struct idmap_key key;
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key.map_up = true;
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key.count = 1;
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key.id = id;
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return bsearch(&key, map->reverse, extents,
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sizeof(struct uid_gid_extent), cmp_map_id);
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}
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static u32 map_id_up(struct uid_gid_map *map, u32 id)
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{
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struct uid_gid_extent *extent;
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unsigned extents = map->nr_extents;
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smp_rmb();
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if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
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extent = map_id_up_base(extents, map, id);
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else
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extent = map_id_up_max(extents, map, id);
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/* Map the id or note failure */
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if (extent)
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id = (id - extent->lower_first) + extent->first;
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else
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id = (u32) -1;
|
|
|
|
return id;
|
|
}
|
|
|
|
/**
|
|
* make_kuid - Map a user-namespace uid pair into a kuid.
|
|
* @ns: User namespace that the uid is in
|
|
* @uid: User identifier
|
|
*
|
|
* Maps a user-namespace uid pair into a kernel internal kuid,
|
|
* and returns that kuid.
|
|
*
|
|
* When there is no mapping defined for the user-namespace uid
|
|
* pair INVALID_UID is returned. Callers are expected to test
|
|
* for and handle INVALID_UID being returned. INVALID_UID
|
|
* may be tested for using uid_valid().
|
|
*/
|
|
kuid_t make_kuid(struct user_namespace *ns, uid_t uid)
|
|
{
|
|
/* Map the uid to a global kernel uid */
|
|
return KUIDT_INIT(map_id_down(&ns->uid_map, uid));
|
|
}
|
|
EXPORT_SYMBOL(make_kuid);
|
|
|
|
/**
|
|
* from_kuid - Create a uid from a kuid user-namespace pair.
|
|
* @targ: The user namespace we want a uid in.
|
|
* @kuid: The kernel internal uid to start with.
|
|
*
|
|
* Map @kuid into the user-namespace specified by @targ and
|
|
* return the resulting uid.
|
|
*
|
|
* There is always a mapping into the initial user_namespace.
|
|
*
|
|
* If @kuid has no mapping in @targ (uid_t)-1 is returned.
|
|
*/
|
|
uid_t from_kuid(struct user_namespace *targ, kuid_t kuid)
|
|
{
|
|
/* Map the uid from a global kernel uid */
|
|
return map_id_up(&targ->uid_map, __kuid_val(kuid));
|
|
}
|
|
EXPORT_SYMBOL(from_kuid);
|
|
|
|
/**
|
|
* from_kuid_munged - Create a uid from a kuid user-namespace pair.
|
|
* @targ: The user namespace we want a uid in.
|
|
* @kuid: The kernel internal uid to start with.
|
|
*
|
|
* Map @kuid into the user-namespace specified by @targ and
|
|
* return the resulting uid.
|
|
*
|
|
* There is always a mapping into the initial user_namespace.
|
|
*
|
|
* Unlike from_kuid from_kuid_munged never fails and always
|
|
* returns a valid uid. This makes from_kuid_munged appropriate
|
|
* for use in syscalls like stat and getuid where failing the
|
|
* system call and failing to provide a valid uid are not an
|
|
* options.
|
|
*
|
|
* If @kuid has no mapping in @targ overflowuid is returned.
|
|
*/
|
|
uid_t from_kuid_munged(struct user_namespace *targ, kuid_t kuid)
|
|
{
|
|
uid_t uid;
|
|
uid = from_kuid(targ, kuid);
|
|
|
|
if (uid == (uid_t) -1)
|
|
uid = overflowuid;
|
|
return uid;
|
|
}
|
|
EXPORT_SYMBOL(from_kuid_munged);
|
|
|
|
/**
|
|
* make_kgid - Map a user-namespace gid pair into a kgid.
|
|
* @ns: User namespace that the gid is in
|
|
* @gid: group identifier
|
|
*
|
|
* Maps a user-namespace gid pair into a kernel internal kgid,
|
|
* and returns that kgid.
|
|
*
|
|
* When there is no mapping defined for the user-namespace gid
|
|
* pair INVALID_GID is returned. Callers are expected to test
|
|
* for and handle INVALID_GID being returned. INVALID_GID may be
|
|
* tested for using gid_valid().
|
|
*/
|
|
kgid_t make_kgid(struct user_namespace *ns, gid_t gid)
|
|
{
|
|
/* Map the gid to a global kernel gid */
|
|
return KGIDT_INIT(map_id_down(&ns->gid_map, gid));
|
|
}
|
|
EXPORT_SYMBOL(make_kgid);
|
|
|
|
/**
|
|
* from_kgid - Create a gid from a kgid user-namespace pair.
|
|
* @targ: The user namespace we want a gid in.
|
|
* @kgid: The kernel internal gid to start with.
|
|
*
|
|
* Map @kgid into the user-namespace specified by @targ and
|
|
* return the resulting gid.
|
|
*
|
|
* There is always a mapping into the initial user_namespace.
|
|
*
|
|
* If @kgid has no mapping in @targ (gid_t)-1 is returned.
|
|
*/
|
|
gid_t from_kgid(struct user_namespace *targ, kgid_t kgid)
|
|
{
|
|
/* Map the gid from a global kernel gid */
|
|
return map_id_up(&targ->gid_map, __kgid_val(kgid));
|
|
}
|
|
EXPORT_SYMBOL(from_kgid);
|
|
|
|
/**
|
|
* from_kgid_munged - Create a gid from a kgid user-namespace pair.
|
|
* @targ: The user namespace we want a gid in.
|
|
* @kgid: The kernel internal gid to start with.
|
|
*
|
|
* Map @kgid into the user-namespace specified by @targ and
|
|
* return the resulting gid.
|
|
*
|
|
* There is always a mapping into the initial user_namespace.
|
|
*
|
|
* Unlike from_kgid from_kgid_munged never fails and always
|
|
* returns a valid gid. This makes from_kgid_munged appropriate
|
|
* for use in syscalls like stat and getgid where failing the
|
|
* system call and failing to provide a valid gid are not options.
|
|
*
|
|
* If @kgid has no mapping in @targ overflowgid is returned.
|
|
*/
|
|
gid_t from_kgid_munged(struct user_namespace *targ, kgid_t kgid)
|
|
{
|
|
gid_t gid;
|
|
gid = from_kgid(targ, kgid);
|
|
|
|
if (gid == (gid_t) -1)
|
|
gid = overflowgid;
|
|
return gid;
|
|
}
|
|
EXPORT_SYMBOL(from_kgid_munged);
|
|
|
|
/**
|
|
* make_kprojid - Map a user-namespace projid pair into a kprojid.
|
|
* @ns: User namespace that the projid is in
|
|
* @projid: Project identifier
|
|
*
|
|
* Maps a user-namespace uid pair into a kernel internal kuid,
|
|
* and returns that kuid.
|
|
*
|
|
* When there is no mapping defined for the user-namespace projid
|
|
* pair INVALID_PROJID is returned. Callers are expected to test
|
|
* for and handle handle INVALID_PROJID being returned. INVALID_PROJID
|
|
* may be tested for using projid_valid().
|
|
*/
|
|
kprojid_t make_kprojid(struct user_namespace *ns, projid_t projid)
|
|
{
|
|
/* Map the uid to a global kernel uid */
|
|
return KPROJIDT_INIT(map_id_down(&ns->projid_map, projid));
|
|
}
|
|
EXPORT_SYMBOL(make_kprojid);
|
|
|
|
/**
|
|
* from_kprojid - Create a projid from a kprojid user-namespace pair.
|
|
* @targ: The user namespace we want a projid in.
|
|
* @kprojid: The kernel internal project identifier to start with.
|
|
*
|
|
* Map @kprojid into the user-namespace specified by @targ and
|
|
* return the resulting projid.
|
|
*
|
|
* There is always a mapping into the initial user_namespace.
|
|
*
|
|
* If @kprojid has no mapping in @targ (projid_t)-1 is returned.
|
|
*/
|
|
projid_t from_kprojid(struct user_namespace *targ, kprojid_t kprojid)
|
|
{
|
|
/* Map the uid from a global kernel uid */
|
|
return map_id_up(&targ->projid_map, __kprojid_val(kprojid));
|
|
}
|
|
EXPORT_SYMBOL(from_kprojid);
|
|
|
|
/**
|
|
* from_kprojid_munged - Create a projiid from a kprojid user-namespace pair.
|
|
* @targ: The user namespace we want a projid in.
|
|
* @kprojid: The kernel internal projid to start with.
|
|
*
|
|
* Map @kprojid into the user-namespace specified by @targ and
|
|
* return the resulting projid.
|
|
*
|
|
* There is always a mapping into the initial user_namespace.
|
|
*
|
|
* Unlike from_kprojid from_kprojid_munged never fails and always
|
|
* returns a valid projid. This makes from_kprojid_munged
|
|
* appropriate for use in syscalls like stat and where
|
|
* failing the system call and failing to provide a valid projid are
|
|
* not an options.
|
|
*
|
|
* If @kprojid has no mapping in @targ OVERFLOW_PROJID is returned.
|
|
*/
|
|
projid_t from_kprojid_munged(struct user_namespace *targ, kprojid_t kprojid)
|
|
{
|
|
projid_t projid;
|
|
projid = from_kprojid(targ, kprojid);
|
|
|
|
if (projid == (projid_t) -1)
|
|
projid = OVERFLOW_PROJID;
|
|
return projid;
|
|
}
|
|
EXPORT_SYMBOL(from_kprojid_munged);
|
|
|
|
|
|
static int uid_m_show(struct seq_file *seq, void *v)
|
|
{
|
|
struct user_namespace *ns = seq->private;
|
|
struct uid_gid_extent *extent = v;
|
|
struct user_namespace *lower_ns;
|
|
uid_t lower;
|
|
|
|
lower_ns = seq_user_ns(seq);
|
|
if ((lower_ns == ns) && lower_ns->parent)
|
|
lower_ns = lower_ns->parent;
|
|
|
|
lower = from_kuid(lower_ns, KUIDT_INIT(extent->lower_first));
|
|
|
|
seq_printf(seq, "%10u %10u %10u\n",
|
|
extent->first,
|
|
lower,
|
|
extent->count);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int gid_m_show(struct seq_file *seq, void *v)
|
|
{
|
|
struct user_namespace *ns = seq->private;
|
|
struct uid_gid_extent *extent = v;
|
|
struct user_namespace *lower_ns;
|
|
gid_t lower;
|
|
|
|
lower_ns = seq_user_ns(seq);
|
|
if ((lower_ns == ns) && lower_ns->parent)
|
|
lower_ns = lower_ns->parent;
|
|
|
|
lower = from_kgid(lower_ns, KGIDT_INIT(extent->lower_first));
|
|
|
|
seq_printf(seq, "%10u %10u %10u\n",
|
|
extent->first,
|
|
lower,
|
|
extent->count);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int projid_m_show(struct seq_file *seq, void *v)
|
|
{
|
|
struct user_namespace *ns = seq->private;
|
|
struct uid_gid_extent *extent = v;
|
|
struct user_namespace *lower_ns;
|
|
projid_t lower;
|
|
|
|
lower_ns = seq_user_ns(seq);
|
|
if ((lower_ns == ns) && lower_ns->parent)
|
|
lower_ns = lower_ns->parent;
|
|
|
|
lower = from_kprojid(lower_ns, KPROJIDT_INIT(extent->lower_first));
|
|
|
|
seq_printf(seq, "%10u %10u %10u\n",
|
|
extent->first,
|
|
lower,
|
|
extent->count);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void *m_start(struct seq_file *seq, loff_t *ppos,
|
|
struct uid_gid_map *map)
|
|
{
|
|
loff_t pos = *ppos;
|
|
unsigned extents = map->nr_extents;
|
|
smp_rmb();
|
|
|
|
if (pos >= extents)
|
|
return NULL;
|
|
|
|
if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
|
|
return &map->extent[pos];
|
|
|
|
return &map->forward[pos];
|
|
}
|
|
|
|
static void *uid_m_start(struct seq_file *seq, loff_t *ppos)
|
|
{
|
|
struct user_namespace *ns = seq->private;
|
|
|
|
return m_start(seq, ppos, &ns->uid_map);
|
|
}
|
|
|
|
static void *gid_m_start(struct seq_file *seq, loff_t *ppos)
|
|
{
|
|
struct user_namespace *ns = seq->private;
|
|
|
|
return m_start(seq, ppos, &ns->gid_map);
|
|
}
|
|
|
|
static void *projid_m_start(struct seq_file *seq, loff_t *ppos)
|
|
{
|
|
struct user_namespace *ns = seq->private;
|
|
|
|
return m_start(seq, ppos, &ns->projid_map);
|
|
}
|
|
|
|
static void *m_next(struct seq_file *seq, void *v, loff_t *pos)
|
|
{
|
|
(*pos)++;
|
|
return seq->op->start(seq, pos);
|
|
}
|
|
|
|
static void m_stop(struct seq_file *seq, void *v)
|
|
{
|
|
return;
|
|
}
|
|
|
|
const struct seq_operations proc_uid_seq_operations = {
|
|
.start = uid_m_start,
|
|
.stop = m_stop,
|
|
.next = m_next,
|
|
.show = uid_m_show,
|
|
};
|
|
|
|
const struct seq_operations proc_gid_seq_operations = {
|
|
.start = gid_m_start,
|
|
.stop = m_stop,
|
|
.next = m_next,
|
|
.show = gid_m_show,
|
|
};
|
|
|
|
const struct seq_operations proc_projid_seq_operations = {
|
|
.start = projid_m_start,
|
|
.stop = m_stop,
|
|
.next = m_next,
|
|
.show = projid_m_show,
|
|
};
|
|
|
|
static bool mappings_overlap(struct uid_gid_map *new_map,
|
|
struct uid_gid_extent *extent)
|
|
{
|
|
u32 upper_first, lower_first, upper_last, lower_last;
|
|
unsigned idx;
|
|
|
|
upper_first = extent->first;
|
|
lower_first = extent->lower_first;
|
|
upper_last = upper_first + extent->count - 1;
|
|
lower_last = lower_first + extent->count - 1;
|
|
|
|
for (idx = 0; idx < new_map->nr_extents; idx++) {
|
|
u32 prev_upper_first, prev_lower_first;
|
|
u32 prev_upper_last, prev_lower_last;
|
|
struct uid_gid_extent *prev;
|
|
|
|
if (new_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
|
|
prev = &new_map->extent[idx];
|
|
else
|
|
prev = &new_map->forward[idx];
|
|
|
|
prev_upper_first = prev->first;
|
|
prev_lower_first = prev->lower_first;
|
|
prev_upper_last = prev_upper_first + prev->count - 1;
|
|
prev_lower_last = prev_lower_first + prev->count - 1;
|
|
|
|
/* Does the upper range intersect a previous extent? */
|
|
if ((prev_upper_first <= upper_last) &&
|
|
(prev_upper_last >= upper_first))
|
|
return true;
|
|
|
|
/* Does the lower range intersect a previous extent? */
|
|
if ((prev_lower_first <= lower_last) &&
|
|
(prev_lower_last >= lower_first))
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* insert_extent - Safely insert a new idmap extent into struct uid_gid_map.
|
|
* Takes care to allocate a 4K block of memory if the number of mappings exceeds
|
|
* UID_GID_MAP_MAX_BASE_EXTENTS.
|
|
*/
|
|
static int insert_extent(struct uid_gid_map *map, struct uid_gid_extent *extent)
|
|
{
|
|
struct uid_gid_extent *dest;
|
|
|
|
if (map->nr_extents == UID_GID_MAP_MAX_BASE_EXTENTS) {
|
|
struct uid_gid_extent *forward;
|
|
|
|
/* Allocate memory for 340 mappings. */
|
|
forward = kmalloc_array(UID_GID_MAP_MAX_EXTENTS,
|
|
sizeof(struct uid_gid_extent),
|
|
GFP_KERNEL);
|
|
if (!forward)
|
|
return -ENOMEM;
|
|
|
|
/* Copy over memory. Only set up memory for the forward pointer.
|
|
* Defer the memory setup for the reverse pointer.
|
|
*/
|
|
memcpy(forward, map->extent,
|
|
map->nr_extents * sizeof(map->extent[0]));
|
|
|
|
map->forward = forward;
|
|
map->reverse = NULL;
|
|
}
|
|
|
|
if (map->nr_extents < UID_GID_MAP_MAX_BASE_EXTENTS)
|
|
dest = &map->extent[map->nr_extents];
|
|
else
|
|
dest = &map->forward[map->nr_extents];
|
|
|
|
*dest = *extent;
|
|
map->nr_extents++;
|
|
return 0;
|
|
}
|
|
|
|
/* cmp function to sort() forward mappings */
|
|
static int cmp_extents_forward(const void *a, const void *b)
|
|
{
|
|
const struct uid_gid_extent *e1 = a;
|
|
const struct uid_gid_extent *e2 = b;
|
|
|
|
if (e1->first < e2->first)
|
|
return -1;
|
|
|
|
if (e1->first > e2->first)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* cmp function to sort() reverse mappings */
|
|
static int cmp_extents_reverse(const void *a, const void *b)
|
|
{
|
|
const struct uid_gid_extent *e1 = a;
|
|
const struct uid_gid_extent *e2 = b;
|
|
|
|
if (e1->lower_first < e2->lower_first)
|
|
return -1;
|
|
|
|
if (e1->lower_first > e2->lower_first)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* sort_idmaps - Sorts an array of idmap entries.
|
|
* Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS.
|
|
*/
|
|
static int sort_idmaps(struct uid_gid_map *map)
|
|
{
|
|
if (map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
|
|
return 0;
|
|
|
|
/* Sort forward array. */
|
|
sort(map->forward, map->nr_extents, sizeof(struct uid_gid_extent),
|
|
cmp_extents_forward, NULL);
|
|
|
|
/* Only copy the memory from forward we actually need. */
|
|
map->reverse = kmemdup(map->forward,
|
|
map->nr_extents * sizeof(struct uid_gid_extent),
|
|
GFP_KERNEL);
|
|
if (!map->reverse)
|
|
return -ENOMEM;
|
|
|
|
/* Sort reverse array. */
|
|
sort(map->reverse, map->nr_extents, sizeof(struct uid_gid_extent),
|
|
cmp_extents_reverse, NULL);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static ssize_t map_write(struct file *file, const char __user *buf,
|
|
size_t count, loff_t *ppos,
|
|
int cap_setid,
|
|
struct uid_gid_map *map,
|
|
struct uid_gid_map *parent_map)
|
|
{
|
|
struct seq_file *seq = file->private_data;
|
|
struct user_namespace *ns = seq->private;
|
|
struct uid_gid_map new_map;
|
|
unsigned idx;
|
|
struct uid_gid_extent extent;
|
|
char *kbuf = NULL, *pos, *next_line;
|
|
ssize_t ret = -EINVAL;
|
|
|
|
/*
|
|
* The userns_state_mutex serializes all writes to any given map.
|
|
*
|
|
* Any map is only ever written once.
|
|
*
|
|
* An id map fits within 1 cache line on most architectures.
|
|
*
|
|
* On read nothing needs to be done unless you are on an
|
|
* architecture with a crazy cache coherency model like alpha.
|
|
*
|
|
* There is a one time data dependency between reading the
|
|
* count of the extents and the values of the extents. The
|
|
* desired behavior is to see the values of the extents that
|
|
* were written before the count of the extents.
|
|
*
|
|
* To achieve this smp_wmb() is used on guarantee the write
|
|
* order and smp_rmb() is guaranteed that we don't have crazy
|
|
* architectures returning stale data.
|
|
*/
|
|
mutex_lock(&userns_state_mutex);
|
|
|
|
memset(&new_map, 0, sizeof(struct uid_gid_map));
|
|
|
|
ret = -EPERM;
|
|
/* Only allow one successful write to the map */
|
|
if (map->nr_extents != 0)
|
|
goto out;
|
|
|
|
/*
|
|
* Adjusting namespace settings requires capabilities on the target.
|
|
*/
|
|
if (cap_valid(cap_setid) && !file_ns_capable(file, ns, CAP_SYS_ADMIN))
|
|
goto out;
|
|
|
|
/* Only allow < page size writes at the beginning of the file */
|
|
ret = -EINVAL;
|
|
if ((*ppos != 0) || (count >= PAGE_SIZE))
|
|
goto out;
|
|
|
|
/* Slurp in the user data */
|
|
kbuf = memdup_user_nul(buf, count);
|
|
if (IS_ERR(kbuf)) {
|
|
ret = PTR_ERR(kbuf);
|
|
kbuf = NULL;
|
|
goto out;
|
|
}
|
|
|
|
/* Parse the user data */
|
|
ret = -EINVAL;
|
|
pos = kbuf;
|
|
for (; pos; pos = next_line) {
|
|
|
|
/* Find the end of line and ensure I don't look past it */
|
|
next_line = strchr(pos, '\n');
|
|
if (next_line) {
|
|
*next_line = '\0';
|
|
next_line++;
|
|
if (*next_line == '\0')
|
|
next_line = NULL;
|
|
}
|
|
|
|
pos = skip_spaces(pos);
|
|
extent.first = simple_strtoul(pos, &pos, 10);
|
|
if (!isspace(*pos))
|
|
goto out;
|
|
|
|
pos = skip_spaces(pos);
|
|
extent.lower_first = simple_strtoul(pos, &pos, 10);
|
|
if (!isspace(*pos))
|
|
goto out;
|
|
|
|
pos = skip_spaces(pos);
|
|
extent.count = simple_strtoul(pos, &pos, 10);
|
|
if (*pos && !isspace(*pos))
|
|
goto out;
|
|
|
|
/* Verify there is not trailing junk on the line */
|
|
pos = skip_spaces(pos);
|
|
if (*pos != '\0')
|
|
goto out;
|
|
|
|
/* Verify we have been given valid starting values */
|
|
if ((extent.first == (u32) -1) ||
|
|
(extent.lower_first == (u32) -1))
|
|
goto out;
|
|
|
|
/* Verify count is not zero and does not cause the
|
|
* extent to wrap
|
|
*/
|
|
if ((extent.first + extent.count) <= extent.first)
|
|
goto out;
|
|
if ((extent.lower_first + extent.count) <=
|
|
extent.lower_first)
|
|
goto out;
|
|
|
|
/* Do the ranges in extent overlap any previous extents? */
|
|
if (mappings_overlap(&new_map, &extent))
|
|
goto out;
|
|
|
|
if ((new_map.nr_extents + 1) == UID_GID_MAP_MAX_EXTENTS &&
|
|
(next_line != NULL))
|
|
goto out;
|
|
|
|
ret = insert_extent(&new_map, &extent);
|
|
if (ret < 0)
|
|
goto out;
|
|
ret = -EINVAL;
|
|
}
|
|
/* Be very certaint 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))
|
|
goto out;
|
|
|
|
ret = sort_idmaps(&new_map);
|
|
if (ret < 0)
|
|
goto out;
|
|
|
|
ret = -EPERM;
|
|
/* Map the lower ids from the parent user namespace to the
|
|
* kernel global id space.
|
|
*/
|
|
for (idx = 0; idx < new_map.nr_extents; idx++) {
|
|
struct uid_gid_extent *e;
|
|
u32 lower_first;
|
|
|
|
if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
|
|
e = &new_map.extent[idx];
|
|
else
|
|
e = &new_map.forward[idx];
|
|
|
|
lower_first = map_id_range_down(parent_map,
|
|
e->lower_first,
|
|
e->count);
|
|
|
|
/* Fail if we can not map the specified extent to
|
|
* the kernel global id space.
|
|
*/
|
|
if (lower_first == (u32) -1)
|
|
goto out;
|
|
|
|
e->lower_first = lower_first;
|
|
}
|
|
|
|
/* Install the map */
|
|
if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) {
|
|
memcpy(map->extent, new_map.extent,
|
|
new_map.nr_extents * sizeof(new_map.extent[0]));
|
|
} else {
|
|
map->forward = new_map.forward;
|
|
map->reverse = new_map.reverse;
|
|
}
|
|
smp_wmb();
|
|
map->nr_extents = new_map.nr_extents;
|
|
|
|
*ppos = count;
|
|
ret = count;
|
|
out:
|
|
if (ret < 0 && new_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) {
|
|
kfree(new_map.forward);
|
|
kfree(new_map.reverse);
|
|
map->forward = NULL;
|
|
map->reverse = NULL;
|
|
map->nr_extents = 0;
|
|
}
|
|
|
|
mutex_unlock(&userns_state_mutex);
|
|
kfree(kbuf);
|
|
return ret;
|
|
}
|
|
|
|
ssize_t proc_uid_map_write(struct file *file, const char __user *buf,
|
|
size_t size, loff_t *ppos)
|
|
{
|
|
struct seq_file *seq = file->private_data;
|
|
struct user_namespace *ns = seq->private;
|
|
struct user_namespace *seq_ns = seq_user_ns(seq);
|
|
|
|
if (!ns->parent)
|
|
return -EPERM;
|
|
|
|
if ((seq_ns != ns) && (seq_ns != ns->parent))
|
|
return -EPERM;
|
|
|
|
return map_write(file, buf, size, ppos, CAP_SETUID,
|
|
&ns->uid_map, &ns->parent->uid_map);
|
|
}
|
|
|
|
ssize_t proc_gid_map_write(struct file *file, const char __user *buf,
|
|
size_t size, loff_t *ppos)
|
|
{
|
|
struct seq_file *seq = file->private_data;
|
|
struct user_namespace *ns = seq->private;
|
|
struct user_namespace *seq_ns = seq_user_ns(seq);
|
|
|
|
if (!ns->parent)
|
|
return -EPERM;
|
|
|
|
if ((seq_ns != ns) && (seq_ns != ns->parent))
|
|
return -EPERM;
|
|
|
|
return map_write(file, buf, size, ppos, CAP_SETGID,
|
|
&ns->gid_map, &ns->parent->gid_map);
|
|
}
|
|
|
|
ssize_t proc_projid_map_write(struct file *file, const char __user *buf,
|
|
size_t size, loff_t *ppos)
|
|
{
|
|
struct seq_file *seq = file->private_data;
|
|
struct user_namespace *ns = seq->private;
|
|
struct user_namespace *seq_ns = seq_user_ns(seq);
|
|
|
|
if (!ns->parent)
|
|
return -EPERM;
|
|
|
|
if ((seq_ns != ns) && (seq_ns != ns->parent))
|
|
return -EPERM;
|
|
|
|
/* Anyone can set any valid project id no capability needed */
|
|
return map_write(file, buf, size, ppos, -1,
|
|
&ns->projid_map, &ns->parent->projid_map);
|
|
}
|
|
|
|
static bool new_idmap_permitted(const struct file *file,
|
|
struct user_namespace *ns, int cap_setid,
|
|
struct uid_gid_map *new_map)
|
|
{
|
|
const struct cred *cred = file->f_cred;
|
|
/* Don't allow mappings that would allow anything that wouldn't
|
|
* be allowed without the establishment of unprivileged mappings.
|
|
*/
|
|
if ((new_map->nr_extents == 1) && (new_map->extent[0].count == 1) &&
|
|
uid_eq(ns->owner, cred->euid)) {
|
|
u32 id = new_map->extent[0].lower_first;
|
|
if (cap_setid == CAP_SETUID) {
|
|
kuid_t uid = make_kuid(ns->parent, id);
|
|
if (uid_eq(uid, cred->euid))
|
|
return true;
|
|
} else if (cap_setid == CAP_SETGID) {
|
|
kgid_t gid = make_kgid(ns->parent, id);
|
|
if (!(ns->flags & USERNS_SETGROUPS_ALLOWED) &&
|
|
gid_eq(gid, cred->egid))
|
|
return true;
|
|
}
|
|
}
|
|
|
|
/* Allow anyone to set a mapping that doesn't require privilege */
|
|
if (!cap_valid(cap_setid))
|
|
return true;
|
|
|
|
/* 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.
|
|
*/
|
|
if (ns_capable(ns->parent, cap_setid) &&
|
|
file_ns_capable(file, ns->parent, cap_setid))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
int proc_setgroups_show(struct seq_file *seq, void *v)
|
|
{
|
|
struct user_namespace *ns = seq->private;
|
|
unsigned long userns_flags = READ_ONCE(ns->flags);
|
|
|
|
seq_printf(seq, "%s\n",
|
|
(userns_flags & USERNS_SETGROUPS_ALLOWED) ?
|
|
"allow" : "deny");
|
|
return 0;
|
|
}
|
|
|
|
ssize_t proc_setgroups_write(struct file *file, const char __user *buf,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
struct seq_file *seq = file->private_data;
|
|
struct user_namespace *ns = seq->private;
|
|
char kbuf[8], *pos;
|
|
bool setgroups_allowed;
|
|
ssize_t ret;
|
|
|
|
/* Only allow a very narrow range of strings to be written */
|
|
ret = -EINVAL;
|
|
if ((*ppos != 0) || (count >= sizeof(kbuf)))
|
|
goto out;
|
|
|
|
/* What was written? */
|
|
ret = -EFAULT;
|
|
if (copy_from_user(kbuf, buf, count))
|
|
goto out;
|
|
kbuf[count] = '\0';
|
|
pos = kbuf;
|
|
|
|
/* What is being requested? */
|
|
ret = -EINVAL;
|
|
if (strncmp(pos, "allow", 5) == 0) {
|
|
pos += 5;
|
|
setgroups_allowed = true;
|
|
}
|
|
else if (strncmp(pos, "deny", 4) == 0) {
|
|
pos += 4;
|
|
setgroups_allowed = false;
|
|
}
|
|
else
|
|
goto out;
|
|
|
|
/* Verify there is not trailing junk on the line */
|
|
pos = skip_spaces(pos);
|
|
if (*pos != '\0')
|
|
goto out;
|
|
|
|
ret = -EPERM;
|
|
mutex_lock(&userns_state_mutex);
|
|
if (setgroups_allowed) {
|
|
/* Enabling setgroups after setgroups has been disabled
|
|
* is not allowed.
|
|
*/
|
|
if (!(ns->flags & USERNS_SETGROUPS_ALLOWED))
|
|
goto out_unlock;
|
|
} else {
|
|
/* Permanently disabling setgroups after setgroups has
|
|
* been enabled by writing the gid_map is not allowed.
|
|
*/
|
|
if (ns->gid_map.nr_extents != 0)
|
|
goto out_unlock;
|
|
ns->flags &= ~USERNS_SETGROUPS_ALLOWED;
|
|
}
|
|
mutex_unlock(&userns_state_mutex);
|
|
|
|
/* Report a successful write */
|
|
*ppos = count;
|
|
ret = count;
|
|
out:
|
|
return ret;
|
|
out_unlock:
|
|
mutex_unlock(&userns_state_mutex);
|
|
goto out;
|
|
}
|
|
|
|
bool userns_may_setgroups(const struct user_namespace *ns)
|
|
{
|
|
bool allowed;
|
|
|
|
mutex_lock(&userns_state_mutex);
|
|
/* It is not safe to use setgroups until a gid mapping in
|
|
* the user namespace has been established.
|
|
*/
|
|
allowed = ns->gid_map.nr_extents != 0;
|
|
/* Is setgroups allowed? */
|
|
allowed = allowed && (ns->flags & USERNS_SETGROUPS_ALLOWED);
|
|
mutex_unlock(&userns_state_mutex);
|
|
|
|
return allowed;
|
|
}
|
|
|
|
/*
|
|
* Returns true if @child is the same namespace or a descendant of
|
|
* @ancestor.
|
|
*/
|
|
bool in_userns(const struct user_namespace *ancestor,
|
|
const struct user_namespace *child)
|
|
{
|
|
const struct user_namespace *ns;
|
|
for (ns = child; ns->level > ancestor->level; ns = ns->parent)
|
|
;
|
|
return (ns == ancestor);
|
|
}
|
|
|
|
bool current_in_userns(const struct user_namespace *target_ns)
|
|
{
|
|
return in_userns(target_ns, current_user_ns());
|
|
}
|
|
EXPORT_SYMBOL(current_in_userns);
|
|
|
|
static inline struct user_namespace *to_user_ns(struct ns_common *ns)
|
|
{
|
|
return container_of(ns, struct user_namespace, ns);
|
|
}
|
|
|
|
static struct ns_common *userns_get(struct task_struct *task)
|
|
{
|
|
struct user_namespace *user_ns;
|
|
|
|
rcu_read_lock();
|
|
user_ns = get_user_ns(__task_cred(task)->user_ns);
|
|
rcu_read_unlock();
|
|
|
|
return user_ns ? &user_ns->ns : NULL;
|
|
}
|
|
|
|
static void userns_put(struct ns_common *ns)
|
|
{
|
|
put_user_ns(to_user_ns(ns));
|
|
}
|
|
|
|
static int userns_install(struct nsproxy *nsproxy, struct ns_common *ns)
|
|
{
|
|
struct user_namespace *user_ns = to_user_ns(ns);
|
|
struct cred *cred;
|
|
|
|
/* Don't allow gaining capabilities by reentering
|
|
* the same user namespace.
|
|
*/
|
|
if (user_ns == current_user_ns())
|
|
return -EINVAL;
|
|
|
|
/* Tasks that share a thread group must share a user namespace */
|
|
if (!thread_group_empty(current))
|
|
return -EINVAL;
|
|
|
|
if (current->fs->users != 1)
|
|
return -EINVAL;
|
|
|
|
if (!ns_capable(user_ns, CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
cred = prepare_creds();
|
|
if (!cred)
|
|
return -ENOMEM;
|
|
|
|
put_user_ns(cred->user_ns);
|
|
set_cred_user_ns(cred, get_user_ns(user_ns));
|
|
|
|
return commit_creds(cred);
|
|
}
|
|
|
|
struct ns_common *ns_get_owner(struct ns_common *ns)
|
|
{
|
|
struct user_namespace *my_user_ns = current_user_ns();
|
|
struct user_namespace *owner, *p;
|
|
|
|
/* See if the owner is in the current user namespace */
|
|
owner = p = ns->ops->owner(ns);
|
|
for (;;) {
|
|
if (!p)
|
|
return ERR_PTR(-EPERM);
|
|
if (p == my_user_ns)
|
|
break;
|
|
p = p->parent;
|
|
}
|
|
|
|
return &get_user_ns(owner)->ns;
|
|
}
|
|
|
|
static struct user_namespace *userns_owner(struct ns_common *ns)
|
|
{
|
|
return to_user_ns(ns)->parent;
|
|
}
|
|
|
|
const struct proc_ns_operations userns_operations = {
|
|
.name = "user",
|
|
.type = CLONE_NEWUSER,
|
|
.get = userns_get,
|
|
.put = userns_put,
|
|
.install = userns_install,
|
|
.owner = userns_owner,
|
|
.get_parent = ns_get_owner,
|
|
};
|
|
|
|
static __init int user_namespaces_init(void)
|
|
{
|
|
user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC);
|
|
return 0;
|
|
}
|
|
subsys_initcall(user_namespaces_init);
|