Directly suppress automount on the following:
[l]stat
[l]getxattr
[l]setxattr
[l]listxattr
[l]removexattr
name_to_handle_at
fstatat
statfs
utimes
But provide an AT_AUTOMOUNT_FOLLOW path where possible to override that
behaviour.
This changes the behaviour back to before the in-VFS automount patches were
applied, thus, for example, preventing stat() from causing automounting, but
allows it to be overridden where possible.
However, what about the following:
umount
faccessat
fchmodat, chmod
fchownat, lchown, chown
Should these or should these not cause automounting?
It's possible that with these additions, the whole decision point in
follow_automount() can be reduced to just a check of LOOKUP_NO_AUTOMOUNT.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---
fs/fhandle.c | 2 +-
fs/stat.c | 8 ++++----
fs/statfs.c | 3 ++-
fs/utimes.c | 10 +++++++---
fs/xattr.c | 20 ++++++++++++--------
include/linux/fcntl.h | 1 +
6 files changed, 27 insertions(+), 17 deletions(-)
diff --git a/fs/fhandle.c b/fs/fhandle.c
index 6b08864..bc0f327 100644
--- a/fs/fhandle.c
+++ b/fs/fhandle.c
@@ -92,7 +92,7 @@ SYSCALL_DEFINE5(name_to_handle_at, int, dfd, const char __user *, name,
int, flag)
{
struct path path;
- int lookup_flags;
+ int lookup_flags = LOOKUP_NO_AUTOMOUNT;
int err;
if ((flag & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
diff --git a/fs/stat.c b/fs/stat.c
index ba5316f..e39b489 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -73,16 +73,16 @@ int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
{
struct path path;
int error = -EINVAL;
- int lookup_flags = 0;
+ int lookup_flags = LOOKUP_NO_AUTOMOUNT;
if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
- AT_EMPTY_PATH)) != 0)
+ AT_EMPTY_PATH | AT_AUTOMOUNT_FOLLOW)) != 0)
goto out;
if (!(flag & AT_SYMLINK_NOFOLLOW))
lookup_flags |= LOOKUP_FOLLOW;
- if (flag & AT_NO_AUTOMOUNT)
- lookup_flags |= LOOKUP_NO_AUTOMOUNT;
+ if (!(flag & AT_AUTOMOUNT_FOLLOW))
+ lookup_flags &= ~LOOKUP_NO_AUTOMOUNT;
if (flag & AT_EMPTY_PATH)
lookup_flags |= LOOKUP_EMPTY;
diff --git a/fs/statfs.c b/fs/statfs.c
index 8244924..fe64701 100644
--- a/fs/statfs.c
+++ b/fs/statfs.c
@@ -76,7 +76,8 @@ EXPORT_SYMBOL(vfs_statfs);
int user_statfs(const char __user *pathname, struct kstatfs *st)
{
struct path path;
- int error = user_path(pathname, &path);
+ int error = user_path_at(AT_FDCWD, pathname, LOOKUP_NO_AUTOMOUNT,
+ &path);
if (!error) {
error = vfs_statfs(&path, st);
path_put(&path);
diff --git a/fs/utimes.c b/fs/utimes.c
index ba653f3..e9bf196 100644
--- a/fs/utimes.c
+++ b/fs/utimes.c
@@ -136,13 +136,15 @@ long do_utimes(int dfd, const char __user *filename, struct timespec *times,
goto out;
}
- if (flags & ~AT_SYMLINK_NOFOLLOW)
+ if (flags & ~(AT_SYMLINK_NOFOLLOW |
+ AT_NO_AUTOMOUNT | AT_AUTOMOUNT_FOLLOW))
goto out;
if (filename == NULL && dfd != AT_FDCWD) {
struct file *file;
- if (flags & AT_SYMLINK_NOFOLLOW)
+ if (flags & (AT_SYMLINK_NOFOLLOW |
+ AT_NO_AUTOMOUNT | AT_AUTOMOUNT_FOLLOW))
goto out;
file = fget(dfd);
@@ -154,10 +156,12 @@ long do_utimes(int dfd, const char __user *filename, struct timespec *times,
fput(file);
} else {
struct path path;
- int lookup_flags = 0;
+ int lookup_flags = LOOKUP_NO_AUTOMOUNT;
if (!(flags & AT_SYMLINK_NOFOLLOW))
lookup_flags |= LOOKUP_FOLLOW;
+ if (flags & AT_AUTOMOUNT_FOLLOW)
+ lookup_flags &= ~LOOKUP_NO_AUTOMOUNT;
error = user_path_at(dfd, filename, lookup_flags, &path);
if (error)
diff --git a/fs/xattr.c b/fs/xattr.c
index f060663..7c462ae 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -290,7 +290,8 @@ SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
struct path path;
int error;
- error = user_path(pathname, &path);
+ error = user_path_at(AT_FDCWD, pathname,
+ LOOKUP_FOLLOW | LOOKUP_NO_AUTOMOUNT, &path);
if (error)
return error;
error = mnt_want_write(path.mnt);
@@ -309,7 +310,7 @@ SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
struct path path;
int error;
- error = user_lpath(pathname, &path);
+ error = user_path_at(AT_FDCWD, pathname, LOOKUP_NO_AUTOMOUNT, &path);
if (error)
return error;
error = mnt_want_write(path.mnt);
@@ -386,7 +387,8 @@ SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
struct path path;
ssize_t error;
- error = user_path(pathname, &path);
+ error = user_path_at(AT_FDCWD, pathname,
+ LOOKUP_FOLLOW | LOOKUP_NO_AUTOMOUNT, &path);
if (error)
return error;
error = getxattr(path.dentry, name, value, size);
@@ -400,7 +402,7 @@ SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
struct path path;
ssize_t error;
- error = user_lpath(pathname, &path);
+ error = user_path_at(AT_FDCWD, pathname, LOOKUP_NO_AUTOMOUNT, &path);
if (error)
return error;
error = getxattr(path.dentry, name, value, size);
@@ -459,7 +461,8 @@ SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
struct path path;
ssize_t error;
- error = user_path(pathname, &path);
+ error = user_path_at(AT_FDCWD, pathname,
+ LOOKUP_FOLLOW | LOOKUP_NO_AUTOMOUNT, &path);
if (error)
return error;
error = listxattr(path.dentry, list, size);
@@ -473,7 +476,7 @@ SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
struct path path;
ssize_t error;
- error = user_lpath(pathname, &path);
+ error = user_path_at(AT_FDCWD, pathname, LOOKUP_NO_AUTOMOUNT, &path);
if (error)
return error;
error = listxattr(path.dentry, list, size);
@@ -519,7 +522,8 @@ SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
struct path path;
int error;
- error = user_path(pathname, &path);
+ error = user_path_at(AT_FDCWD, pathname,
+ LOOKUP_FOLLOW | LOOKUP_NO_AUTOMOUNT, &path);
if (error)
return error;
error = mnt_want_write(path.mnt);
@@ -537,7 +541,7 @@ SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
struct path path;
int error;
- error = user_lpath(pathname, &path);
+ error = user_path_at(AT_FDCWD, pathname, LOOKUP_NO_AUTOMOUNT, &path);
if (error)
return error;
error = mnt_want_write(path.mnt);
diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h
index f550f89..768fb66 100644
--- a/include/linux/fcntl.h
+++ b/include/linux/fcntl.h
@@ -47,6 +47,7 @@
#define AT_SYMLINK_FOLLOW 0x400 /* Follow symbolic links. */
#define AT_NO_AUTOMOUNT 0x800 /* Suppress terminal automount traversal */
#define AT_EMPTY_PATH 0x1000 /* Allow empty relative pathname */
+#define AT_AUTOMOUNT_FOLLOW 0x2000 /* Follow terminal automounts */
#ifdef __KERNEL__
--
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