From ee97cd872d08b8623076f2a63ffb872d0884411a Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Tue, 21 Aug 2012 12:26:45 -0400
Subject: switch flush_unauthorized_files() to replace_fd()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 security/selinux/hooks.c | 47 +++++++++++++++--------------------------------
 1 file changed, 15 insertions(+), 32 deletions(-)

(limited to 'security')

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 6c77f63c759..00b50113642 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2126,8 +2126,6 @@ static inline void flush_unauthorized_files(const struct cred *cred,
 	spin_lock(&files->file_lock);
 	for (;;) {
 		unsigned long set, i;
-		int fd;
-
 		j++;
 		i = j * BITS_PER_LONG;
 		fdt = files_fdtable(files);
@@ -2138,38 +2136,23 @@ static inline void flush_unauthorized_files(const struct cred *cred,
 			continue;
 		spin_unlock(&files->file_lock);
 		for ( ; set ; i++, set >>= 1) {
-			if (set & 1) {
-				file = fget(i);
-				if (!file)
-					continue;
-				if (file_has_perm(cred,
-						  file,
-						  file_to_av(file))) {
-					sys_close(i);
-					fd = get_unused_fd();
-					if (fd != i) {
-						if (fd >= 0)
-							put_unused_fd(fd);
-						fput(file);
-						continue;
-					}
-					if (devnull) {
-						get_file(devnull);
-					} else {
-						devnull = dentry_open(
-							&selinux_null,
-							O_RDWR, cred);
-						if (IS_ERR(devnull)) {
-							devnull = NULL;
-							put_unused_fd(fd);
-							fput(file);
-							continue;
-						}
-					}
-					fd_install(fd, devnull);
+			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;
 				}
-				fput(file);
+				replace_fd(i, devnull, 0);
 			}
+			fput(file);
 		}
 		spin_lock(&files->file_lock);
 
-- 
cgit v1.2.3


From c3c073f808b22dfae15ef8412b6f7b998644139a Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Tue, 21 Aug 2012 22:32:06 -0400
Subject: 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>
---
 drivers/tty/tty_io.c      | 36 +++++++++++-------------------
 fs/file.c                 | 21 +++++++++++++++++
 include/linux/fdtable.h   |  3 +++
 net/core/netprio_cgroup.c | 38 ++++++++++---------------------
 security/selinux/hooks.c  | 57 ++++++++++++++++++-----------------------------
 5 files changed, 71 insertions(+), 84 deletions(-)

(limited to 'security')

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index b425c79675a..71d95cfbabe 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2791,6 +2791,13 @@ static long tty_compat_ioctl(struct file *file, unsigned int cmd,
 }
 #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 @@ void __do_SAK(struct tty_struct *tty)
 	struct task_struct *g, *p;
 	struct pid *session;
 	int		i;
-	struct file	*filp;
-	struct fdtable *fdt;
 
 	if (!tty)
 		return;
@@ -2849,27 +2854,12 @@ void __do_SAK(struct tty_struct *tty)
 			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 967bd0dadbe..e6e41812258 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -979,3 +979,24 @@ int f_dupfd(unsigned int from, struct file *file, unsigned flags)
 	}
 	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 de2b71caa0f..fb7dacae052 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -98,6 +98,9 @@ void reset_files_struct(struct files_struct *);
 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 c75e3f9d060..5ffd084c6a8 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c
@@ -272,38 +272,24 @@ out_free_devname:
 	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 00b50113642..4dfbcea10eb 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2088,15 +2088,19 @@ static int selinux_bprm_secureexec(struct linux_binprm *bprm)
 	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 @@ static inline void flush_unauthorized_files(const struct cred *cred,
 		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);
 }
 
 /*
-- 
cgit v1.2.3


From cb0942b81249798e15c3f04eee2946ef543e8115 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Mon, 27 Aug 2012 14:48:26 -0400
Subject: make get_file() return its argument

simplifies a bunch of callers...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/ia64/kernel/perfmon.c         | 4 +---
 drivers/base/dma-buf.c             | 3 +--
 drivers/staging/omapdrm/omap_gem.c | 3 +--
 drivers/tty/tty_io.c               | 9 +++------
 fs/autofs4/waitq.c                 | 3 +--
 fs/fuse/dev.c                      | 3 +--
 fs/nfsd/nfs4state.c                | 3 +--
 fs/proc/base.c                     | 3 +--
 fs/select.c                        | 3 +--
 include/linux/fs.h                 | 6 +++++-
 mm/fremap.c                        | 3 +--
 mm/mmap.c                          | 3 +--
 mm/nommu.c                         | 6 ++----
 net/compat.c                       | 3 +--
 net/core/scm.c                     | 3 +--
 security/selinux/hooks.c           | 3 +--
 16 files changed, 23 insertions(+), 38 deletions(-)

(limited to 'security')

diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c
index 79826c13b8b..ff5d4e4c373 100644
--- a/arch/ia64/kernel/perfmon.c
+++ b/arch/ia64/kernel/perfmon.c
@@ -2306,7 +2306,7 @@ pfm_smpl_buffer_alloc(struct task_struct *task, struct file *filp, pfm_context_t
 	 * partially initialize the vma for the sampling buffer
 	 */
 	vma->vm_mm	     = mm;
-	vma->vm_file	     = filp;
+	vma->vm_file	     = get_file(filp);
 	vma->vm_flags	     = VM_READ| VM_MAYREAD |VM_RESERVED;
 	vma->vm_page_prot    = PAGE_READONLY; /* XXX may need to change */
 
@@ -2345,8 +2345,6 @@ pfm_smpl_buffer_alloc(struct task_struct *task, struct file *filp, pfm_context_t
 		goto error;
 	}
 
-	get_file(filp);
-
 	/*
 	 * now insert the vma in the vm list for the process, must be
 	 * done with mmap lock held
diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index c30f3e1d0ef..460e22dee36 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -460,8 +460,7 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
 	if (vma->vm_file)
 		fput(vma->vm_file);
 
-	vma->vm_file = dmabuf->file;
-	get_file(vma->vm_file);
+	vma->vm_file = get_file(dmabuf->file);
 
 	vma->vm_pgoff = pgoff;
 
diff --git a/drivers/staging/omapdrm/omap_gem.c b/drivers/staging/omapdrm/omap_gem.c
index 3a0d035a9e0..2a6bb7f9ee6 100644
--- a/drivers/staging/omapdrm/omap_gem.c
+++ b/drivers/staging/omapdrm/omap_gem.c
@@ -566,9 +566,8 @@ int omap_gem_mmap_obj(struct drm_gem_object *obj,
 		 * in particular in the case of mmap'd dmabufs)
 		 */
 		fput(vma->vm_file);
-		get_file(obj->filp);
 		vma->vm_pgoff = 0;
-		vma->vm_file  = obj->filp;
+		vma->vm_file  = get_file(obj->filp);
 
 		vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 	}
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 71d95cfbabe..c7561f29d89 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1163,10 +1163,8 @@ ssize_t redirected_tty_write(struct file *file, const char __user *buf,
 	struct file *p = NULL;
 
 	spin_lock(&redirect_lock);
-	if (redirect) {
-		get_file(redirect);
-		p = redirect;
-	}
+	if (redirect)
+		p = get_file(redirect);
 	spin_unlock(&redirect_lock);
 
 	if (p) {
@@ -2246,8 +2244,7 @@ static int tioccons(struct file *file)
 		spin_unlock(&redirect_lock);
 		return -EBUSY;
 	}
-	get_file(file);
-	redirect = file;
+	redirect = get_file(file);
 	spin_unlock(&redirect_lock);
 	return 0;
 }
diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index da8876d38a7..dce436e595c 100644
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -175,8 +175,7 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
 		return;
 	}
 
-	pipe = sbi->pipe;
-	get_file(pipe);
+	pipe = get_file(sbi->pipe);
 
 	mutex_unlock(&sbi->wq_mutex);
 
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index f4246cfc8d8..8c23fa7a91e 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -148,8 +148,7 @@ static struct fuse_req *get_reserved_req(struct fuse_conn *fc,
 		if (ff->reserved_req) {
 			req = ff->reserved_req;
 			ff->reserved_req = NULL;
-			get_file(file);
-			req->stolen_file = file;
+			req->stolen_file = get_file(file);
 		}
 		spin_unlock(&fc->lock);
 	} while (!req);
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index cc894eda385..48a1bad3733 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2837,8 +2837,7 @@ static int nfs4_setlease(struct nfs4_delegation *dp, int flag)
 		return -ENOMEM;
 	}
 	fp->fi_lease = fl;
-	fp->fi_deleg_file = fl->fl_file;
-	get_file(fp->fi_deleg_file);
+	fp->fi_deleg_file = get_file(fl->fl_file);
 	atomic_set(&fp->fi_delegees, 1);
 	list_add(&dp->dl_perfile, &fp->fi_delegations);
 	return 0;
diff --git a/fs/proc/base.c b/fs/proc/base.c
index b55c3bb298e..f1e8438d21b 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1979,8 +1979,7 @@ proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
 				if (++pos <= filp->f_pos)
 					continue;
 
-				get_file(vma->vm_file);
-				info.file = vma->vm_file;
+				info.file = get_file(vma->vm_file);
 				info.len = snprintf(info.name,
 						sizeof(info.name), "%lx-%lx",
 						vma->vm_start, vma->vm_end);
diff --git a/fs/select.c b/fs/select.c
index db14c781335..ffdd16d6e69 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -220,8 +220,7 @@ static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
 	struct poll_table_entry *entry = poll_get_entry(pwq);
 	if (!entry)
 		return;
-	get_file(filp);
-	entry->filp = filp;
+	entry->filp = get_file(filp);
 	entry->wait_address = wait_address;
 	entry->key = p->_key;
 	init_waitqueue_func_entry(&entry->wait, pollwake);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index aa110476a95..de1db1c1208 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1074,7 +1074,11 @@ struct file_handle {
 	unsigned char f_handle[0];
 };
 
-#define get_file(x)	atomic_long_inc(&(x)->f_count)
+static inline struct file *get_file(struct file *f)
+{
+	atomic_long_inc(&f->f_count);
+	return f;
+}
 #define fput_atomic(x)	atomic_long_add_unless(&(x)->f_count, -1, 1)
 #define file_count(x)	atomic_long_read(&(x)->f_count)
 
diff --git a/mm/fremap.c b/mm/fremap.c
index 9ed4fd43246..048659c0c03 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -195,10 +195,9 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 		 */
 		if (mapping_cap_account_dirty(mapping)) {
 			unsigned long addr;
-			struct file *file = vma->vm_file;
+			struct file *file = get_file(vma->vm_file);
 
 			flags &= MAP_NONBLOCK;
-			get_file(file);
 			addr = mmap_region(file, start, size,
 					flags, vma->vm_flags, pgoff);
 			fput(file);
diff --git a/mm/mmap.c b/mm/mmap.c
index ae18a48e7e4..872441e8191 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1301,8 +1301,7 @@ munmap_back:
 				goto free_vma;
 			correct_wcount = 1;
 		}
-		vma->vm_file = file;
-		get_file(file);
+		vma->vm_file = get_file(file);
 		error = file->f_op->mmap(file, vma);
 		if (error)
 			goto unmap_and_free_vma;
diff --git a/mm/nommu.c b/mm/nommu.c
index d4b0c10872d..dee2ff89fd5 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1282,10 +1282,8 @@ unsigned long do_mmap_pgoff(struct file *file,
 	vma->vm_pgoff = pgoff;
 
 	if (file) {
-		region->vm_file = file;
-		get_file(file);
-		vma->vm_file = file;
-		get_file(file);
+		region->vm_file = get_file(file);
+		vma->vm_file = get_file(file);
 		if (vm_flags & VM_EXECUTABLE) {
 			added_exe_file_vma(current->mm);
 			vma->vm_mm = current->mm;
diff --git a/net/compat.c b/net/compat.c
index 74ed1d7a84a..79ae8848500 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -301,8 +301,7 @@ void scm_detach_fds_compat(struct msghdr *kmsg, struct scm_cookie *scm)
 			break;
 		}
 		/* Bump the usage count and install the file. */
-		get_file(fp[i]);
-		fd_install(new_fd, fp[i]);
+		fd_install(new_fd, get_file(fp[i]));
 	}
 
 	if (i > 0) {
diff --git a/net/core/scm.c b/net/core/scm.c
index 040cebeed45..b0098d25923 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -281,11 +281,10 @@ void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
 			break;
 		}
 		/* Bump the usage count and install the file. */
-		get_file(fp[i]);
 		sock = sock_from_file(fp[i], &err);
 		if (sock)
 			sock_update_netprioidx(sock->sk, current);
-		fd_install(new_fd, fp[i]);
+		fd_install(new_fd, get_file(fp[i]));
 	}
 
 	if (i > 0)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 4dfbcea10eb..651d8456611 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2135,8 +2135,7 @@ static inline void flush_unauthorized_files(const struct cred *cred,
 	if (!IS_ERR(devnull)) {
 		/* replace all the matching ones with this */
 		do {
-			get_file(devnull);
-			replace_fd(n - 1, devnull, 0);
+			replace_fd(n - 1, get_file(devnull), 0);
 		} while ((n = iterate_fd(files, n, match_file, cred)) != 0);
 		fput(devnull);
 	} else {
-- 
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