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-rw-r--r--fs/exec.c10
-rw-r--r--fs/libfs.c2
-rw-r--r--fs/namespace.c33
-rw-r--r--fs/nsfs.c10
-rw-r--r--fs/open.c2
-rw-r--r--fs/proc/root.c2
-rw-r--r--fs/sysfs/mount.c4
-rw-r--r--include/linux/fs.h3
-rw-r--r--kernel/fork.c36
-rw-r--r--kernel/sys.c3
-rw-r--r--kernel/user_namespace.c4
-rw-r--r--mm/mmap.c4
-rw-r--r--mm/nommu.c2
-rw-r--r--security/security.c2
14 files changed, 83 insertions, 34 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 1977c2a553ac..b06623a9347f 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -98,6 +98,12 @@ static inline void put_binfmt(struct linux_binfmt * fmt)
module_put(fmt->module);
}
+bool path_noexec(const struct path *path)
+{
+ return (path->mnt->mnt_flags & MNT_NOEXEC) ||
+ (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
+}
+
#ifdef CONFIG_USELIB
/*
* Note that a shared library must be both readable and executable due to
@@ -132,7 +138,7 @@ SYSCALL_DEFINE1(uselib, const char __user *, library)
goto exit;
error = -EACCES;
- if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
+ if (path_noexec(&file->f_path))
goto exit;
fsnotify_open(file);
@@ -777,7 +783,7 @@ static struct file *do_open_execat(int fd, struct filename *name, int flags)
if (!S_ISREG(file_inode(file)->i_mode))
goto exit;
- if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
+ if (path_noexec(&file->f_path))
goto exit;
err = deny_write_access(file);
diff --git a/fs/libfs.c b/fs/libfs.c
index 102edfd39000..c7cbfb092e94 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1185,7 +1185,7 @@ void make_empty_dir_inode(struct inode *inode)
inode->i_uid = GLOBAL_ROOT_UID;
inode->i_gid = GLOBAL_ROOT_GID;
inode->i_rdev = 0;
- inode->i_size = 2;
+ inode->i_size = 0;
inode->i_blkbits = PAGE_SHIFT;
inode->i_blocks = 0;
diff --git a/fs/namespace.c b/fs/namespace.c
index 2b8aa15fd6df..0570729c87fd 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3218,6 +3218,8 @@ static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags)
down_read(&namespace_sem);
list_for_each_entry(mnt, &ns->list, mnt_list) {
struct mount *child;
+ int mnt_flags;
+
if (mnt->mnt.mnt_sb->s_type != type)
continue;
@@ -3227,17 +3229,30 @@ static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags)
if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root)
continue;
+ /* Read the mount flags and filter out flags that
+ * may safely be ignored.
+ */
+ mnt_flags = mnt->mnt.mnt_flags;
+ if (mnt->mnt.mnt_sb->s_iflags & SB_I_NOEXEC)
+ mnt_flags &= ~(MNT_LOCK_NOSUID | MNT_LOCK_NOEXEC);
+
/* Verify the mount flags are equal to or more permissive
* than the proposed new mount.
*/
- if ((mnt->mnt.mnt_flags & MNT_LOCK_READONLY) &&
+ if ((mnt_flags & MNT_LOCK_READONLY) &&
!(new_flags & MNT_READONLY))
continue;
- if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) &&
+ if ((mnt_flags & MNT_LOCK_NODEV) &&
!(new_flags & MNT_NODEV))
continue;
- if ((mnt->mnt.mnt_flags & MNT_LOCK_ATIME) &&
- ((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK)))
+ if ((mnt_flags & MNT_LOCK_NOSUID) &&
+ !(new_flags & MNT_NOSUID))
+ continue;
+ if ((mnt_flags & MNT_LOCK_NOEXEC) &&
+ !(new_flags & MNT_NOEXEC))
+ continue;
+ if ((mnt_flags & MNT_LOCK_ATIME) &&
+ ((mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK)))
continue;
/* This mount is not fully visible if there are any
@@ -3247,16 +3262,18 @@ static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags)
list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) {
struct inode *inode = child->mnt_mountpoint->d_inode;
/* Only worry about locked mounts */
- if (!(mnt->mnt.mnt_flags & MNT_LOCKED))
+ if (!(mnt_flags & MNT_LOCKED))
continue;
/* Is the directory permanetly empty? */
if (!is_empty_dir_inode(inode))
goto next;
}
/* Preserve the locked attributes */
- *new_mnt_flags |= mnt->mnt.mnt_flags & (MNT_LOCK_READONLY | \
- MNT_LOCK_NODEV | \
- MNT_LOCK_ATIME);
+ *new_mnt_flags |= mnt_flags & (MNT_LOCK_READONLY | \
+ MNT_LOCK_NODEV | \
+ MNT_LOCK_NOSUID | \
+ MNT_LOCK_NOEXEC | \
+ MNT_LOCK_ATIME);
visible = true;
goto found;
next: ;
diff --git a/fs/nsfs.c b/fs/nsfs.c
index 99521e7c492b..e4905fbf3396 100644
--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -4,6 +4,7 @@
#include <linux/proc_ns.h>
#include <linux/magic.h>
#include <linux/ktime.h>
+#include <linux/seq_file.h>
static struct vfsmount *nsfs_mnt;
@@ -136,9 +137,18 @@ out_invalid:
return ERR_PTR(-EINVAL);
}
+static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)
+{
+ struct inode *inode = d_inode(dentry);
+ const struct proc_ns_operations *ns_ops = dentry->d_fsdata;
+
+ return seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino);
+}
+
static const struct super_operations nsfs_ops = {
.statfs = simple_statfs,
.evict_inode = nsfs_evict,
+ .show_path = nsfs_show_path,
};
static struct dentry *nsfs_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
diff --git a/fs/open.c b/fs/open.c
index e33dab287fa0..b6f1e96a7c0b 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -377,7 +377,7 @@ retry:
* with the "noexec" flag.
*/
res = -EACCES;
- if (path.mnt->mnt_flags & MNT_NOEXEC)
+ if (path_noexec(&path))
goto out_path_release;
}
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 68feb0f70e63..361ab4ee42fc 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -134,6 +134,8 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
}
sb->s_flags |= MS_ACTIVE;
+ /* User space would break if executables appear on proc */
+ sb->s_iflags |= SB_I_NOEXEC;
}
return dget(sb->s_root);
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 1c6ac6fcee9f..f3db82071cfb 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -40,6 +40,10 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
SYSFS_MAGIC, &new_sb, ns);
if (IS_ERR(root) || !new_sb)
kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
+ else if (new_sb)
+ /* Userspace would break if executables appear on sysfs */
+ root->d_sb->s_iflags |= SB_I_NOEXEC;
+
return root;
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 84b783f277f7..fbd780c33c5f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1260,6 +1260,7 @@ struct mm_struct;
/* sb->s_iflags */
#define SB_I_CGROUPWB 0x00000001 /* cgroup-aware writeback enabled */
+#define SB_I_NOEXEC 0x00000002 /* Ignore executables on this fs */
/* Possible states of 'frozen' field */
enum {
@@ -3041,4 +3042,6 @@ static inline bool dir_relax(struct inode *inode)
return !IS_DEADDIR(inode);
}
+extern bool path_noexec(const struct path *path);
+
#endif /* _LINUX_FS_H */
diff --git a/kernel/fork.c b/kernel/fork.c
index 0d93b4d0617b..2b1a61cddc19 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1280,10 +1280,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
/*
* If the new process will be in a different pid or user namespace
- * do not allow it to share a thread group or signal handlers or
- * parent with the forking task.
+ * do not allow it to share a thread group with the forking task.
*/
- if (clone_flags & CLONE_SIGHAND) {
+ if (clone_flags & CLONE_THREAD) {
if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
(task_active_pid_ns(current) !=
current->nsproxy->pid_ns_for_children))
@@ -1872,13 +1871,21 @@ static int check_unshare_flags(unsigned long unshare_flags)
CLONE_NEWUSER|CLONE_NEWPID))
return -EINVAL;
/*
- * Not implemented, but pretend it works if there is nothing to
- * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
- * needs to unshare vm.
+ * Not implemented, but pretend it works if there is nothing
+ * to unshare. Note that unsharing the address space or the
+ * signal handlers also need to unshare the signal queues (aka
+ * CLONE_THREAD).
*/
if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
- /* FIXME: get_task_mm() increments ->mm_users */
- if (atomic_read(&current->mm->mm_users) > 1)
+ if (!thread_group_empty(current))
+ return -EINVAL;
+ }
+ if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
+ if (atomic_read(&current->sighand->count) > 1)
+ return -EINVAL;
+ }
+ if (unshare_flags & CLONE_VM) {
+ if (!current_is_single_threaded())
return -EINVAL;
}
@@ -1942,21 +1949,22 @@ SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
int err;
/*
- * If unsharing a user namespace must also unshare the thread.
+ * If unsharing a user namespace must also unshare the thread group
+ * and unshare the filesystem root and working directories.
*/
if (unshare_flags & CLONE_NEWUSER)
unshare_flags |= CLONE_THREAD | CLONE_FS;
/*
- * If unsharing a thread from a thread group, must also unshare vm.
- */
- if (unshare_flags & CLONE_THREAD)
- unshare_flags |= CLONE_VM;
- /*
* If unsharing vm, must also unshare signal handlers.
*/
if (unshare_flags & CLONE_VM)
unshare_flags |= CLONE_SIGHAND;
/*
+ * If unsharing a signal handlers, must also unshare the signal queues.
+ */
+ if (unshare_flags & CLONE_SIGHAND)
+ unshare_flags |= CLONE_THREAD;
+ /*
* If unsharing namespace, must also unshare filesystem information.
*/
if (unshare_flags & CLONE_NEWNS)
diff --git a/kernel/sys.c b/kernel/sys.c
index 259fda25eb6b..fa2f2f671a5c 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1668,8 +1668,7 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
* overall picture.
*/
err = -EACCES;
- if (!S_ISREG(inode->i_mode) ||
- exe.file->f_path.mnt->mnt_flags & MNT_NOEXEC)
+ if (!S_ISREG(inode->i_mode) || path_noexec(&exe.file->f_path))
goto exit;
err = inode_permission(inode, MAY_EXEC);
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 4109f8320684..f65a0a06a8c0 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -976,8 +976,8 @@ static int userns_install(struct nsproxy *nsproxy, struct ns_common *ns)
if (user_ns == current_user_ns())
return -EINVAL;
- /* Threaded processes may not enter a different user namespace */
- if (atomic_read(&current->mm->mm_users) > 1)
+ /* Tasks that share a thread group must share a user namespace */
+ if (!thread_group_empty(current))
return -EINVAL;
if (current->fs->users != 1)
diff --git a/mm/mmap.c b/mm/mmap.c
index aa632ade2be7..f126923ce683 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1268,7 +1268,7 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
* mounted, in which case we dont add PROT_EXEC.)
*/
if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
- if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
+ if (!(file && path_noexec(&file->f_path)))
prot |= PROT_EXEC;
if (!(flags & MAP_FIXED))
@@ -1337,7 +1337,7 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
case MAP_PRIVATE:
if (!(file->f_mode & FMODE_READ))
return -EACCES;
- if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
+ if (path_noexec(&file->f_path)) {
if (vm_flags & VM_EXEC)
return -EPERM;
vm_flags &= ~VM_MAYEXEC;
diff --git a/mm/nommu.c b/mm/nommu.c
index 58ea3643b9e9..ce17abf087ff 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1035,7 +1035,7 @@ static int validate_mmap_request(struct file *file,
/* handle executable mappings and implied executable
* mappings */
- if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
+ if (path_noexec(&file->f_path)) {
if (prot & PROT_EXEC)
return -EPERM;
} else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
diff --git a/security/security.c b/security/security.c
index 994283624bdb..75b85fdc4e97 100644
--- a/security/security.c
+++ b/security/security.c
@@ -776,7 +776,7 @@ static inline unsigned long mmap_prot(struct file *file, unsigned long prot)
* ditto if it's not on noexec mount, except that on !MMU we need
* NOMMU_MAP_EXEC (== VM_MAYEXEC) in this case
*/
- if (!(file->f_path.mnt->mnt_flags & MNT_NOEXEC)) {
+ if (!path_noexec(&file->f_path)) {
#ifndef CONFIG_MMU
if (file->f_op->mmap_capabilities) {
unsigned caps = file->f_op->mmap_capabilities(file);
generated by cgit (git 2.34.1) at 2024-05-30 11:23:06 +0000