new helper: iterate_fd()
iterates through the opened files in given descriptor table,
calling a supplied function; we stop once non-zero is returned.
Callback gets struct file *, descriptor number and const void *
argument passed to iterator. It is called with files->file_lock
held, so it is not allowed to block.
tty_io, netprio_cgroup and selinux flush_unauthorized_files()
converted to its use.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index b425c79..71d95cf 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2791,6 +2791,13 @@
}
#endif
+static int this_tty(const void *t, struct file *file, unsigned fd)
+{
+ if (likely(file->f_op->read != tty_read))
+ return 0;
+ return file_tty(file) != t ? 0 : fd + 1;
+}
+
/*
* This implements the "Secure Attention Key" --- the idea is to
* prevent trojan horses by killing all processes associated with this
@@ -2818,8 +2825,6 @@
struct task_struct *g, *p;
struct pid *session;
int i;
- struct file *filp;
- struct fdtable *fdt;
if (!tty)
return;
@@ -2849,27 +2854,12 @@
continue;
}
task_lock(p);
- if (p->files) {
- /*
- * We don't take a ref to the file, so we must
- * hold ->file_lock instead.
- */
- spin_lock(&p->files->file_lock);
- fdt = files_fdtable(p->files);
- for (i = 0; i < fdt->max_fds; i++) {
- filp = fcheck_files(p->files, i);
- if (!filp)
- continue;
- if (filp->f_op->read == tty_read &&
- file_tty(filp) == tty) {
- printk(KERN_NOTICE "SAK: killed process %d"
- " (%s): fd#%d opened to the tty\n",
- task_pid_nr(p), p->comm, i);
- force_sig(SIGKILL, p);
- break;
- }
- }
- spin_unlock(&p->files->file_lock);
+ i = iterate_fd(p->files, 0, this_tty, tty);
+ if (i != 0) {
+ printk(KERN_NOTICE "SAK: killed process %d"
+ " (%s): fd#%d opened to the tty\n",
+ task_pid_nr(p), p->comm, i - 1);
+ force_sig(SIGKILL, p);
}
task_unlock(p);
} while_each_thread(g, p);
diff --git a/fs/file.c b/fs/file.c
index 967bd0d..e6e4181 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -979,3 +979,24 @@
}
return err;
}
+
+int iterate_fd(struct files_struct *files, unsigned n,
+ int (*f)(const void *, struct file *, unsigned),
+ const void *p)
+{
+ struct fdtable *fdt;
+ struct file *file;
+ int res = 0;
+ if (!files)
+ return 0;
+ spin_lock(&files->file_lock);
+ fdt = files_fdtable(files);
+ while (!res && n < fdt->max_fds) {
+ file = rcu_dereference_check_fdtable(files, fdt->fd[n++]);
+ if (file)
+ res = f(p, file, n);
+ }
+ spin_unlock(&files->file_lock);
+ return res;
+}
+EXPORT_SYMBOL(iterate_fd);
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index de2b71c..fb7daca 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -98,6 +98,9 @@
int unshare_files(struct files_struct **);
struct files_struct *dup_fd(struct files_struct *, int *);
void do_close_on_exec(struct files_struct *);
+int iterate_fd(struct files_struct *, unsigned,
+ int (*)(const void *, struct file *, unsigned),
+ const void *);
extern int __alloc_fd(struct files_struct *files,
unsigned start, unsigned end, unsigned flags);
diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
index c75e3f9..5ffd084 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c
@@ -272,38 +272,24 @@
return ret;
}
+static int update_netprio(const void *v, struct file *file, unsigned n)
+{
+ int err;
+ struct socket *sock = sock_from_file(file, &err);
+ if (sock)
+ sock->sk->sk_cgrp_prioidx = (u32)(unsigned long)v;
+ return 0;
+}
+
void net_prio_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
{
struct task_struct *p;
+ void *v;
cgroup_taskset_for_each(p, cgrp, tset) {
- unsigned int fd;
- struct fdtable *fdt;
- struct files_struct *files;
-
task_lock(p);
- files = p->files;
- if (!files) {
- task_unlock(p);
- continue;
- }
-
- spin_lock(&files->file_lock);
- fdt = files_fdtable(files);
- for (fd = 0; fd < fdt->max_fds; fd++) {
- struct file *file;
- struct socket *sock;
- int err;
-
- file = fcheck_files(files, fd);
- if (!file)
- continue;
-
- sock = sock_from_file(file, &err);
- if (sock)
- sock_update_netprioidx(sock->sk, p);
- }
- spin_unlock(&files->file_lock);
+ v = (void *)(unsigned long)task_netprioidx(p);
+ iterate_fd(p->files, 0, update_netprio, v);
task_unlock(p);
}
}
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 00b5011..4dfbcea 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2088,15 +2088,19 @@
return (atsecure || cap_bprm_secureexec(bprm));
}
+static int match_file(const void *p, struct file *file, unsigned fd)
+{
+ return file_has_perm(p, file, file_to_av(file)) ? fd + 1 : 0;
+}
+
/* Derived from fs/exec.c:flush_old_files. */
static inline void flush_unauthorized_files(const struct cred *cred,
struct files_struct *files)
{
struct file *file, *devnull = NULL;
struct tty_struct *tty;
- struct fdtable *fdt;
- long j = -1;
int drop_tty = 0;
+ unsigned n;
tty = get_current_tty();
if (tty) {
@@ -2123,41 +2127,24 @@
no_tty();
/* Revalidate access to inherited open files. */
- spin_lock(&files->file_lock);
- for (;;) {
- unsigned long set, i;
- j++;
- i = j * BITS_PER_LONG;
- fdt = files_fdtable(files);
- if (i >= fdt->max_fds)
- break;
- set = fdt->open_fds[j];
- if (!set)
- continue;
- spin_unlock(&files->file_lock);
- for ( ; set ; i++, set >>= 1) {
- if (!(set & 1))
- continue;
- file = fget(i);
- if (!file)
- continue;
- if (file_has_perm(cred, file, file_to_av(file))) {
- if (devnull) {
- get_file(devnull);
- } else {
- devnull = dentry_open(&selinux_null,
- O_RDWR, cred);
- if (IS_ERR(devnull))
- devnull = NULL;
- }
- replace_fd(i, devnull, 0);
- }
- fput(file);
- }
- spin_lock(&files->file_lock);
+ n = iterate_fd(files, 0, match_file, cred);
+ if (!n) /* none found? */
+ return;
+ devnull = dentry_open(&selinux_null, O_RDWR, cred);
+ if (!IS_ERR(devnull)) {
+ /* replace all the matching ones with this */
+ do {
+ get_file(devnull);
+ replace_fd(n - 1, devnull, 0);
+ } while ((n = iterate_fd(files, n, match_file, cred)) != 0);
+ fput(devnull);
+ } else {
+ /* just close all the matching ones */
+ do {
+ replace_fd(n - 1, NULL, 0);
+ } while ((n = iterate_fd(files, n, match_file, cred)) != 0);
}
- spin_unlock(&files->file_lock);
}
/*
