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-rw-r--r--fs/fcntl.c37
-rw-r--r--fs/file_table.c53
-rw-r--r--fs/namei.c2
-rw-r--r--fs/open.c35
-rw-r--r--include/asm-generic/fcntl.h4
-rw-r--r--include/linux/file.h2
-rw-r--r--include/linux/fs.h3
7 files changed, 119 insertions, 17 deletions
diff --git a/fs/fcntl.c b/fs/fcntl.c
index cb1026181bdc..6c82e5bac039 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -131,7 +131,7 @@ SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd)
SYSCALL_DEFINE1(dup, unsigned int, fildes)
{
int ret = -EBADF;
- struct file *file = fget(fildes);
+ struct file *file = fget_raw(fildes);
if (file) {
ret = get_unused_fd();
@@ -426,15 +426,35 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
return err;
}
+static int check_fcntl_cmd(unsigned cmd)
+{
+ switch (cmd) {
+ case F_DUPFD:
+ case F_DUPFD_CLOEXEC:
+ case F_GETFD:
+ case F_SETFD:
+ case F_GETFL:
+ return 1;
+ }
+ return 0;
+}
+
SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
{
struct file *filp;
long err = -EBADF;
- filp = fget(fd);
+ filp = fget_raw(fd);
if (!filp)
goto out;
+ if (unlikely(filp->f_mode & FMODE_PATH)) {
+ if (!check_fcntl_cmd(cmd)) {
+ fput(filp);
+ goto out;
+ }
+ }
+
err = security_file_fcntl(filp, cmd, arg);
if (err) {
fput(filp);
@@ -456,10 +476,17 @@ SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
long err;
err = -EBADF;
- filp = fget(fd);
+ filp = fget_raw(fd);
if (!filp)
goto out;
+ if (unlikely(filp->f_mode & FMODE_PATH)) {
+ if (!check_fcntl_cmd(cmd)) {
+ fput(filp);
+ goto out;
+ }
+ }
+
err = security_file_fcntl(filp, cmd, arg);
if (err) {
fput(filp);
@@ -808,14 +835,14 @@ static int __init fcntl_init(void)
* Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
* is defined as O_NONBLOCK on some platforms and not on others.
*/
- BUILD_BUG_ON(18 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
+ BUILD_BUG_ON(19 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
O_RDONLY | O_WRONLY | O_RDWR |
O_CREAT | O_EXCL | O_NOCTTY |
O_TRUNC | O_APPEND | /* O_NONBLOCK | */
__O_SYNC | O_DSYNC | FASYNC |
O_DIRECT | O_LARGEFILE | O_DIRECTORY |
O_NOFOLLOW | O_NOATIME | O_CLOEXEC |
- __FMODE_EXEC
+ __FMODE_EXEC | O_PATH
));
fasync_cache = kmem_cache_create("fasync_cache",
diff --git a/fs/file_table.c b/fs/file_table.c
index eb36b6b17e26..3c16e1ca163e 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -276,11 +276,10 @@ struct file *fget(unsigned int fd)
rcu_read_lock();
file = fcheck_files(files, fd);
if (file) {
- if (!atomic_long_inc_not_zero(&file->f_count)) {
- /* File object ref couldn't be taken */
- rcu_read_unlock();
- return NULL;
- }
+ /* File object ref couldn't be taken */
+ if (file->f_mode & FMODE_PATH ||
+ !atomic_long_inc_not_zero(&file->f_count))
+ file = NULL;
}
rcu_read_unlock();
@@ -289,6 +288,23 @@ struct file *fget(unsigned int fd)
EXPORT_SYMBOL(fget);
+struct file *fget_raw(unsigned int fd)
+{
+ struct file *file;
+ struct files_struct *files = current->files;
+
+ rcu_read_lock();
+ file = fcheck_files(files, fd);
+ if (file) {
+ /* File object ref couldn't be taken */
+ if (!atomic_long_inc_not_zero(&file->f_count))
+ file = NULL;
+ }
+ rcu_read_unlock();
+
+ return file;
+}
+
/*
* Lightweight file lookup - no refcnt increment if fd table isn't shared.
*
@@ -313,6 +329,33 @@ struct file *fget_light(unsigned int fd, int *fput_needed)
*fput_needed = 0;
if (atomic_read(&files->count) == 1) {
file = fcheck_files(files, fd);
+ if (file && (file->f_mode & FMODE_PATH))
+ file = NULL;
+ } else {
+ rcu_read_lock();
+ file = fcheck_files(files, fd);
+ if (file) {
+ if (!(file->f_mode & FMODE_PATH) &&
+ atomic_long_inc_not_zero(&file->f_count))
+ *fput_needed = 1;
+ else
+ /* Didn't get the reference, someone's freed */
+ file = NULL;
+ }
+ rcu_read_unlock();
+ }
+
+ return file;
+}
+
+struct file *fget_raw_light(unsigned int fd, int *fput_needed)
+{
+ struct file *file;
+ struct files_struct *files = current->files;
+
+ *fput_needed = 0;
+ if (atomic_read(&files->count) == 1) {
+ file = fcheck_files(files, fd);
} else {
rcu_read_lock();
file = fcheck_files(files, fd);
diff --git a/fs/namei.c b/fs/namei.c
index 33be51a2ddb7..e1d9f90d9776 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1544,7 +1544,7 @@ static int path_init(int dfd, const char *name, unsigned int flags,
} else {
struct dentry *dentry;
- file = fget_light(dfd, &fput_needed);
+ file = fget_raw_light(dfd, &fput_needed);
retval = -EBADF;
if (!file)
goto out_fail;
diff --git a/fs/open.c b/fs/open.c
index 48afc5c139d2..14a51de01f54 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -669,11 +669,16 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
int (*open)(struct inode *, struct file *),
const struct cred *cred)
{
+ static const struct file_operations empty_fops = {};
struct inode *inode;
int error;
f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
FMODE_PREAD | FMODE_PWRITE;
+
+ if (unlikely(f->f_flags & O_PATH))
+ f->f_mode = FMODE_PATH;
+
inode = dentry->d_inode;
if (f->f_mode & FMODE_WRITE) {
error = __get_file_write_access(inode, mnt);
@@ -687,9 +692,15 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
f->f_path.dentry = dentry;
f->f_path.mnt = mnt;
f->f_pos = 0;
- f->f_op = fops_get(inode->i_fop);
file_sb_list_add(f, inode->i_sb);
+ if (unlikely(f->f_mode & FMODE_PATH)) {
+ f->f_op = &empty_fops;
+ return f;
+ }
+
+ f->f_op = fops_get(inode->i_fop);
+
error = security_dentry_open(f, cred);
if (error)
goto cleanup_all;
@@ -911,9 +922,18 @@ static inline int build_open_flags(int flags, int mode, struct open_flags *op)
if (flags & __O_SYNC)
flags |= O_DSYNC;
- op->open_flag = flags;
+ /*
+ * If we have O_PATH in the open flag. Then we
+ * cannot have anything other than the below set of flags
+ */
+ if (flags & O_PATH) {
+ flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
+ acc_mode = 0;
+ } else {
+ acc_mode = MAY_OPEN | ACC_MODE(flags);
+ }
- acc_mode = MAY_OPEN | ACC_MODE(flags);
+ op->open_flag = flags;
/* O_TRUNC implies we need access checks for write permissions */
if (flags & O_TRUNC)
@@ -926,7 +946,8 @@ static inline int build_open_flags(int flags, int mode, struct open_flags *op)
op->acc_mode = acc_mode;
- op->intent = LOOKUP_OPEN;
+ op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
+
if (flags & O_CREAT) {
op->intent |= LOOKUP_CREATE;
if (flags & O_EXCL)
@@ -1053,8 +1074,10 @@ int filp_close(struct file *filp, fl_owner_t id)
if (filp->f_op && filp->f_op->flush)
retval = filp->f_op->flush(filp, id);
- dnotify_flush(filp, id);
- locks_remove_posix(filp, id);
+ if (likely(!(filp->f_mode & FMODE_PATH))) {
+ dnotify_flush(filp, id);
+ locks_remove_posix(filp, id);
+ }
fput(filp);
return retval;
}
diff --git a/include/asm-generic/fcntl.h b/include/asm-generic/fcntl.h
index 0fc16e3f0bfc..84793c7025e2 100644
--- a/include/asm-generic/fcntl.h
+++ b/include/asm-generic/fcntl.h
@@ -80,6 +80,10 @@
#define O_SYNC (__O_SYNC|O_DSYNC)
#endif
+#ifndef O_PATH
+#define O_PATH 010000000
+#endif
+
#ifndef O_NDELAY
#define O_NDELAY O_NONBLOCK
#endif
diff --git a/include/linux/file.h b/include/linux/file.h
index e85baebf6279..21a79958541c 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -29,6 +29,8 @@ static inline void fput_light(struct file *file, int fput_needed)
extern struct file *fget(unsigned int fd);
extern struct file *fget_light(unsigned int fd, int *fput_needed);
+extern struct file *fget_raw(unsigned int fd);
+extern struct file *fget_raw_light(unsigned int fd, int *fput_needed);
extern void set_close_on_exec(unsigned int fd, int flag);
extern void put_filp(struct file *);
extern int alloc_fd(unsigned start, unsigned flags);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f2143e0942c2..13df14e2c42e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -102,6 +102,9 @@ struct inodes_stat_t {
/* File is huge (eg. /dev/kmem): treat loff_t as unsigned */
#define FMODE_UNSIGNED_OFFSET ((__force fmode_t)0x2000)
+/* File is opened with O_PATH; almost nothing can be done with it */
+#define FMODE_PATH ((__force fmode_t)0x4000)
+
/* File was opened by fanotify and shouldn't generate fanotify events */
#define FMODE_NONOTIFY ((__force fmode_t)0x1000000)
generated by cgit v1.2.3 (git 2.0.4) at 2024-11-04 04:26:47 +0000