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synced 2024-11-11 12:28:41 +08:00
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>
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ad47bd7252
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c3c073f808
@ -2791,6 +2791,13 @@ static long tty_compat_ioctl(struct file *file, unsigned int cmd,
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}
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#endif
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static int this_tty(const void *t, struct file *file, unsigned fd)
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{
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if (likely(file->f_op->read != tty_read))
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return 0;
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return file_tty(file) != t ? 0 : fd + 1;
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}
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/*
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* This implements the "Secure Attention Key" --- the idea is to
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* prevent trojan horses by killing all processes associated with this
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@ -2818,8 +2825,6 @@ void __do_SAK(struct tty_struct *tty)
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struct task_struct *g, *p;
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struct pid *session;
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int i;
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struct file *filp;
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struct fdtable *fdt;
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if (!tty)
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return;
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@ -2849,27 +2854,12 @@ void __do_SAK(struct tty_struct *tty)
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continue;
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}
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task_lock(p);
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if (p->files) {
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/*
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* We don't take a ref to the file, so we must
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* hold ->file_lock instead.
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*/
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spin_lock(&p->files->file_lock);
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fdt = files_fdtable(p->files);
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for (i = 0; i < fdt->max_fds; i++) {
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filp = fcheck_files(p->files, i);
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if (!filp)
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continue;
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if (filp->f_op->read == tty_read &&
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file_tty(filp) == tty) {
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printk(KERN_NOTICE "SAK: killed process %d"
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" (%s): fd#%d opened to the tty\n",
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task_pid_nr(p), p->comm, i);
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force_sig(SIGKILL, p);
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break;
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}
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}
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spin_unlock(&p->files->file_lock);
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i = iterate_fd(p->files, 0, this_tty, tty);
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if (i != 0) {
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printk(KERN_NOTICE "SAK: killed process %d"
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" (%s): fd#%d opened to the tty\n",
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task_pid_nr(p), p->comm, i - 1);
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force_sig(SIGKILL, p);
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}
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task_unlock(p);
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} while_each_thread(g, p);
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21
fs/file.c
21
fs/file.c
@ -979,3 +979,24 @@ int f_dupfd(unsigned int from, struct file *file, unsigned flags)
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}
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return err;
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}
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int iterate_fd(struct files_struct *files, unsigned n,
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int (*f)(const void *, struct file *, unsigned),
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const void *p)
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{
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struct fdtable *fdt;
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struct file *file;
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int res = 0;
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if (!files)
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return 0;
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spin_lock(&files->file_lock);
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fdt = files_fdtable(files);
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while (!res && n < fdt->max_fds) {
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file = rcu_dereference_check_fdtable(files, fdt->fd[n++]);
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if (file)
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res = f(p, file, n);
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}
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spin_unlock(&files->file_lock);
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return res;
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}
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EXPORT_SYMBOL(iterate_fd);
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@ -98,6 +98,9 @@ void reset_files_struct(struct files_struct *);
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int unshare_files(struct files_struct **);
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struct files_struct *dup_fd(struct files_struct *, int *);
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void do_close_on_exec(struct files_struct *);
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int iterate_fd(struct files_struct *, unsigned,
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int (*)(const void *, struct file *, unsigned),
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const void *);
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extern int __alloc_fd(struct files_struct *files,
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unsigned start, unsigned end, unsigned flags);
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@ -272,38 +272,24 @@ out_free_devname:
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return ret;
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}
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static int update_netprio(const void *v, struct file *file, unsigned n)
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{
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int err;
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struct socket *sock = sock_from_file(file, &err);
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if (sock)
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sock->sk->sk_cgrp_prioidx = (u32)(unsigned long)v;
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return 0;
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}
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void net_prio_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
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{
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struct task_struct *p;
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void *v;
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cgroup_taskset_for_each(p, cgrp, tset) {
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unsigned int fd;
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struct fdtable *fdt;
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struct files_struct *files;
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task_lock(p);
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files = p->files;
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if (!files) {
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task_unlock(p);
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continue;
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}
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spin_lock(&files->file_lock);
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fdt = files_fdtable(files);
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for (fd = 0; fd < fdt->max_fds; fd++) {
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struct file *file;
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struct socket *sock;
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int err;
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file = fcheck_files(files, fd);
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if (!file)
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continue;
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sock = sock_from_file(file, &err);
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if (sock)
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sock_update_netprioidx(sock->sk, p);
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}
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spin_unlock(&files->file_lock);
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v = (void *)(unsigned long)task_netprioidx(p);
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iterate_fd(p->files, 0, update_netprio, v);
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task_unlock(p);
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}
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}
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@ -2088,15 +2088,19 @@ static int selinux_bprm_secureexec(struct linux_binprm *bprm)
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return (atsecure || cap_bprm_secureexec(bprm));
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}
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static int match_file(const void *p, struct file *file, unsigned fd)
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{
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return file_has_perm(p, file, file_to_av(file)) ? fd + 1 : 0;
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}
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/* Derived from fs/exec.c:flush_old_files. */
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static inline void flush_unauthorized_files(const struct cred *cred,
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struct files_struct *files)
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{
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struct file *file, *devnull = NULL;
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struct tty_struct *tty;
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struct fdtable *fdt;
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long j = -1;
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int drop_tty = 0;
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unsigned n;
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tty = get_current_tty();
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if (tty) {
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@ -2123,41 +2127,24 @@ static inline void flush_unauthorized_files(const struct cred *cred,
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no_tty();
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/* Revalidate access to inherited open files. */
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spin_lock(&files->file_lock);
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for (;;) {
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unsigned long set, i;
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j++;
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i = j * BITS_PER_LONG;
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fdt = files_fdtable(files);
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if (i >= fdt->max_fds)
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break;
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set = fdt->open_fds[j];
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if (!set)
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continue;
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spin_unlock(&files->file_lock);
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for ( ; set ; i++, set >>= 1) {
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if (!(set & 1))
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continue;
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file = fget(i);
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if (!file)
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continue;
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if (file_has_perm(cred, file, file_to_av(file))) {
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if (devnull) {
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get_file(devnull);
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} else {
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devnull = dentry_open(&selinux_null,
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O_RDWR, cred);
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if (IS_ERR(devnull))
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devnull = NULL;
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}
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replace_fd(i, devnull, 0);
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}
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fput(file);
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}
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spin_lock(&files->file_lock);
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n = iterate_fd(files, 0, match_file, cred);
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if (!n) /* none found? */
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return;
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devnull = dentry_open(&selinux_null, O_RDWR, cred);
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if (!IS_ERR(devnull)) {
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/* replace all the matching ones with this */
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do {
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get_file(devnull);
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replace_fd(n - 1, devnull, 0);
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} while ((n = iterate_fd(files, n, match_file, cred)) != 0);
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fput(devnull);
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} else {
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/* just close all the matching ones */
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do {
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replace_fd(n - 1, NULL, 0);
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} while ((n = iterate_fd(files, n, match_file, cred)) != 0);
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}
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spin_unlock(&files->file_lock);
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}
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/*
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