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-rw-r--r--fs/namespace.c54
-rw-r--r--fs/pnode.c6
-rw-r--r--fs/pnode.h1
-rw-r--r--fs/proc/root.c4
-rw-r--r--fs/sysfs/mount.c4
-rw-r--r--include/linux/fs_struct.h2
-rw-r--r--include/linux/mount.h2
-rw-r--r--include/linux/user_namespace.h4
-rw-r--r--ipc/mqueue.c12
-rw-r--r--kernel/pid_namespace.c3
-rw-r--r--kernel/user.c2
-rw-r--r--kernel/user_namespace.c11
-rw-r--r--net/core/scm.c4
-rw-r--r--security/yama/yama_lsm.c4
14 files changed, 105 insertions, 8 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index 50ca17d3cb4..d581e45c0a9 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -798,6 +798,10 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
}
mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~MNT_WRITE_HOLD;
+ /* Don't allow unprivileged users to change mount flags */
+ if ((flag & CL_UNPRIVILEGED) && (mnt->mnt.mnt_flags & MNT_READONLY))
+ mnt->mnt.mnt_flags |= MNT_LOCK_READONLY;
+
atomic_inc(&sb->s_active);
mnt->mnt.mnt_sb = sb;
mnt->mnt.mnt_root = dget(root);
@@ -1713,6 +1717,9 @@ static int change_mount_flags(struct vfsmount *mnt, int ms_flags)
if (readonly_request == __mnt_is_readonly(mnt))
return 0;
+ if (mnt->mnt_flags & MNT_LOCK_READONLY)
+ return -EPERM;
+
if (readonly_request)
error = mnt_make_readonly(real_mount(mnt));
else
@@ -2339,7 +2346,7 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
/* First pass: copy the tree topology */
copy_flags = CL_COPY_ALL | CL_EXPIRE;
if (user_ns != mnt_ns->user_ns)
- copy_flags |= CL_SHARED_TO_SLAVE;
+ copy_flags |= CL_SHARED_TO_SLAVE | CL_UNPRIVILEGED;
new = copy_tree(old, old->mnt.mnt_root, copy_flags);
if (IS_ERR(new)) {
up_write(&namespace_sem);
@@ -2732,6 +2739,51 @@ bool our_mnt(struct vfsmount *mnt)
return check_mnt(real_mount(mnt));
}
+bool current_chrooted(void)
+{
+ /* Does the current process have a non-standard root */
+ struct path ns_root;
+ struct path fs_root;
+ bool chrooted;
+
+ /* Find the namespace root */
+ ns_root.mnt = &current->nsproxy->mnt_ns->root->mnt;
+ ns_root.dentry = ns_root.mnt->mnt_root;
+ path_get(&ns_root);
+ while (d_mountpoint(ns_root.dentry) && follow_down_one(&ns_root))
+ ;
+
+ get_fs_root(current->fs, &fs_root);
+
+ chrooted = !path_equal(&fs_root, &ns_root);
+
+ path_put(&fs_root);
+ path_put(&ns_root);
+
+ return chrooted;
+}
+
+void update_mnt_policy(struct user_namespace *userns)
+{
+ struct mnt_namespace *ns = current->nsproxy->mnt_ns;
+ struct mount *mnt;
+
+ down_read(&namespace_sem);
+ list_for_each_entry(mnt, &ns->list, mnt_list) {
+ switch (mnt->mnt.mnt_sb->s_magic) {
+ case SYSFS_MAGIC:
+ userns->may_mount_sysfs = true;
+ break;
+ case PROC_SUPER_MAGIC:
+ userns->may_mount_proc = true;
+ break;
+ }
+ if (userns->may_mount_sysfs && userns->may_mount_proc)
+ break;
+ }
+ up_read(&namespace_sem);
+}
+
static void *mntns_get(struct task_struct *task)
{
struct mnt_namespace *ns = NULL;
diff --git a/fs/pnode.c b/fs/pnode.c
index 3e000a51ac0..8b29d2164da 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -9,6 +9,7 @@
#include <linux/mnt_namespace.h>
#include <linux/mount.h>
#include <linux/fs.h>
+#include <linux/nsproxy.h>
#include "internal.h"
#include "pnode.h"
@@ -220,6 +221,7 @@ static struct mount *get_source(struct mount *dest,
int propagate_mnt(struct mount *dest_mnt, struct dentry *dest_dentry,
struct mount *source_mnt, struct list_head *tree_list)
{
+ struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns;
struct mount *m, *child;
int ret = 0;
struct mount *prev_dest_mnt = dest_mnt;
@@ -237,6 +239,10 @@ int propagate_mnt(struct mount *dest_mnt, struct dentry *dest_dentry,
source = get_source(m, prev_dest_mnt, prev_src_mnt, &type);
+ /* Notice when we are propagating across user namespaces */
+ if (m->mnt_ns->user_ns != user_ns)
+ type |= CL_UNPRIVILEGED;
+
child = copy_tree(source, source->mnt.mnt_root, type);
if (IS_ERR(child)) {
ret = PTR_ERR(child);
diff --git a/fs/pnode.h b/fs/pnode.h
index 19b853a3445..a0493d5ebfb 100644
--- a/fs/pnode.h
+++ b/fs/pnode.h
@@ -23,6 +23,7 @@
#define CL_MAKE_SHARED 0x08
#define CL_PRIVATE 0x10
#define CL_SHARED_TO_SLAVE 0x20
+#define CL_UNPRIVILEGED 0x40
static inline void set_mnt_shared(struct mount *mnt)
{
diff --git a/fs/proc/root.c b/fs/proc/root.c
index c6e9fac26ba..9c7fab1d23f 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -16,6 +16,7 @@
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/bitops.h>
+#include <linux/user_namespace.h>
#include <linux/mount.h>
#include <linux/pid_namespace.h>
#include <linux/parser.h>
@@ -108,6 +109,9 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
} else {
ns = task_active_pid_ns(current);
options = data;
+
+ if (!current_user_ns()->may_mount_proc)
+ return ERR_PTR(-EPERM);
}
sb = sget(fs_type, proc_test_super, proc_set_super, flags, ns);
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 8d924b5ec73..afd83273e6c 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -19,6 +19,7 @@
#include <linux/module.h>
#include <linux/magic.h>
#include <linux/slab.h>
+#include <linux/user_namespace.h>
#include "sysfs.h"
@@ -111,6 +112,9 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
struct super_block *sb;
int error;
+ if (!(flags & MS_KERNMOUNT) && !current_user_ns()->may_mount_sysfs)
+ return ERR_PTR(-EPERM);
+
info = kzalloc(sizeof(*info), GFP_KERNEL);
if (!info)
return ERR_PTR(-ENOMEM);
diff --git a/include/linux/fs_struct.h b/include/linux/fs_struct.h
index 729eded4b24..2b93a9a5a1e 100644
--- a/include/linux/fs_struct.h
+++ b/include/linux/fs_struct.h
@@ -50,4 +50,6 @@ static inline void get_fs_root_and_pwd(struct fs_struct *fs, struct path *root,
spin_unlock(&fs->lock);
}
+extern bool current_chrooted(void);
+
#endif /* _LINUX_FS_STRUCT_H */
diff --git a/include/linux/mount.h b/include/linux/mount.h
index d7029f4a191..73005f9957e 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -47,6 +47,8 @@ struct mnt_namespace;
#define MNT_INTERNAL 0x4000
+#define MNT_LOCK_READONLY 0x400000
+
struct vfsmount {
struct dentry *mnt_root; /* root of the mounted tree */
struct super_block *mnt_sb; /* pointer to superblock */
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 4ce00932493..b6b215f13b4 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -26,6 +26,8 @@ struct user_namespace {
kuid_t owner;
kgid_t group;
unsigned int proc_inum;
+ bool may_mount_sysfs;
+ bool may_mount_proc;
};
extern struct user_namespace init_user_ns;
@@ -82,4 +84,6 @@ static inline void put_user_ns(struct user_namespace *ns)
#endif
+void update_mnt_policy(struct user_namespace *userns);
+
#endif /* _LINUX_USER_H */
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index 3953fda2e8b..e4e47f64744 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -330,8 +330,16 @@ static struct dentry *mqueue_mount(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data)
{
- if (!(flags & MS_KERNMOUNT))
- data = current->nsproxy->ipc_ns;
+ if (!(flags & MS_KERNMOUNT)) {
+ struct ipc_namespace *ns = current->nsproxy->ipc_ns;
+ /* Don't allow mounting unless the caller has CAP_SYS_ADMIN
+ * over the ipc namespace.
+ */
+ if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
+ return ERR_PTR(-EPERM);
+
+ data = ns;
+ }
return mount_ns(fs_type, flags, data, mqueue_fill_super);
}
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index c1c3dc1c602..bea15bdf82b 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -181,6 +181,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
int nr;
int rc;
struct task_struct *task, *me = current;
+ int init_pids = thread_group_leader(me) ? 1 : 2;
/* Don't allow any more processes into the pid namespace */
disable_pid_allocation(pid_ns);
@@ -230,7 +231,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
*/
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
- if (pid_ns->nr_hashed == 1)
+ if (pid_ns->nr_hashed == init_pids)
break;
schedule();
}
diff --git a/kernel/user.c b/kernel/user.c
index e81978e8c03..8e635a18ab5 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -51,6 +51,8 @@ struct user_namespace init_user_ns = {
.owner = GLOBAL_ROOT_UID,
.group = GLOBAL_ROOT_GID,
.proc_inum = PROC_USER_INIT_INO,
+ .may_mount_sysfs = true,
+ .may_mount_proc = true,
};
EXPORT_SYMBOL_GPL(init_user_ns);
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index b14f4d34204..a54f26f82eb 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -61,6 +61,15 @@ int create_user_ns(struct cred *new)
kgid_t group = new->egid;
int ret;
+ /*
+ * 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
+ * mount namespace which allows all files to be accessed.
+ */
+ if (current_chrooted())
+ return -EPERM;
+
/* The creator needs a mapping in the parent user namespace
* or else we won't be able to reasonably tell userspace who
* created a user_namespace.
@@ -87,6 +96,8 @@ int create_user_ns(struct cred *new)
set_cred_user_ns(new, ns);
+ update_mnt_policy(ns);
+
return 0;
}
diff --git a/net/core/scm.c b/net/core/scm.c
index 905dcc6ad1e..2dc6cdaaae8 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -24,6 +24,7 @@
#include <linux/interrupt.h>
#include <linux/netdevice.h>
#include <linux/security.h>
+#include <linux/pid_namespace.h>
#include <linux/pid.h>
#include <linux/nsproxy.h>
#include <linux/slab.h>
@@ -52,7 +53,8 @@ static __inline__ int scm_check_creds(struct ucred *creds)
if (!uid_valid(uid) || !gid_valid(gid))
return -EINVAL;
- if ((creds->pid == task_tgid_vnr(current) || nsown_capable(CAP_SYS_ADMIN)) &&
+ if ((creds->pid == task_tgid_vnr(current) ||
+ ns_capable(current->nsproxy->pid_ns->user_ns, CAP_SYS_ADMIN)) &&
((uid_eq(uid, cred->uid) || uid_eq(uid, cred->euid) ||
uid_eq(uid, cred->suid)) || nsown_capable(CAP_SETUID)) &&
((gid_eq(gid, cred->gid) || gid_eq(gid, cred->egid) ||
diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 23414b93771..13c88fbcf03 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -347,10 +347,8 @@ int yama_ptrace_traceme(struct task_struct *parent)
/* Only disallow PTRACE_TRACEME on more aggressive settings. */
switch (ptrace_scope) {
case YAMA_SCOPE_CAPABILITY:
- rcu_read_lock();
- if (!ns_capable(__task_cred(parent)->user_ns, CAP_SYS_PTRACE))
+ if (!has_ns_capability(parent, current_user_ns(), CAP_SYS_PTRACE))
rc = -EPERM;
- rcu_read_unlock();
break;
case YAMA_SCOPE_NO_ATTACH:
rc = -EPERM;
generated by cgit v1.2.3-70-g09d2 (git 2.51.2) at 2025-11-04 14:21:20 +0000