diff options
Diffstat (limited to 'fs/file.c')
| -rw-r--r-- | fs/file.c | 189 |
1 files changed, 172 insertions, 17 deletions
diff --git a/fs/file.c b/fs/file.c index abb8b7081d7a..21c0893f2f1d 100644 --- a/fs/file.c +++ b/fs/file.c @@ -10,6 +10,7 @@ #include <linux/syscalls.h> #include <linux/export.h> #include <linux/fs.h> +#include <linux/kernel.h> #include <linux/mm.h> #include <linux/sched/signal.h> #include <linux/slab.h> @@ -18,6 +19,8 @@ #include <linux/bitops.h> #include <linux/spinlock.h> #include <linux/rcupdate.h> +#include <linux/close_range.h> +#include <net/sock.h> unsigned int sysctl_nr_open __read_mostly = 1024*1024; unsigned int sysctl_nr_open_min = BITS_PER_LONG; @@ -264,12 +267,22 @@ static unsigned int count_open_files(struct fdtable *fdt) return i; } +static unsigned int sane_fdtable_size(struct fdtable *fdt, unsigned int max_fds) +{ + unsigned int count; + + count = count_open_files(fdt); + if (max_fds < NR_OPEN_DEFAULT) + max_fds = NR_OPEN_DEFAULT; + return min(count, max_fds); +} + /* * Allocate a new files structure and copy contents from the * passed in files structure. * errorp will be valid only when the returned files_struct is NULL. */ -struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) +struct files_struct *dup_fd(struct files_struct *oldf, unsigned int max_fds, int *errorp) { struct files_struct *newf; struct file **old_fds, **new_fds; @@ -296,7 +309,7 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) spin_lock(&oldf->file_lock); old_fdt = files_fdtable(oldf); - open_files = count_open_files(old_fdt); + open_files = sane_fdtable_size(old_fdt, max_fds); /* * Check whether we need to allocate a larger fd array and fd set. @@ -327,7 +340,7 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) */ spin_lock(&oldf->file_lock); old_fdt = files_fdtable(oldf); - open_files = count_open_files(old_fdt); + open_files = sane_fdtable_size(old_fdt, max_fds); } copy_fd_bitmaps(new_fdt, old_fdt, open_files); @@ -613,6 +626,10 @@ void __fd_install(struct files_struct *files, unsigned int fd, rcu_read_unlock_sched(); } +/* + * This consumes the "file" refcount, so callers should treat it + * as if they had called fput(file). + */ void fd_install(unsigned int fd, struct file *file) { __fd_install(current->files, fd, file); @@ -620,12 +637,9 @@ void fd_install(unsigned int fd, struct file *file) EXPORT_SYMBOL(fd_install); -/* - * The same warnings as for __alloc_fd()/__fd_install() apply here... - */ -int __close_fd(struct files_struct *files, unsigned fd) +static struct file *pick_file(struct files_struct *files, unsigned fd) { - struct file *file; + struct file *file = NULL; struct fdtable *fdt; spin_lock(&files->file_lock); @@ -637,15 +651,105 @@ int __close_fd(struct files_struct *files, unsigned fd) goto out_unlock; rcu_assign_pointer(fdt->fd[fd], NULL); __put_unused_fd(files, fd); - spin_unlock(&files->file_lock); - return filp_close(file, files); out_unlock: spin_unlock(&files->file_lock); - return -EBADF; + return file; +} + +/* + * The same warnings as for __alloc_fd()/__fd_install() apply here... + */ +int __close_fd(struct files_struct *files, unsigned fd) +{ + struct file *file; + + file = pick_file(files, fd); + if (!file) + return -EBADF; + + return filp_close(file, files); } EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ +/** + * __close_range() - Close all file descriptors in a given range. + * + * @fd: starting file descriptor to close + * @max_fd: last file descriptor to close + * + * This closes a range of file descriptors. All file descriptors + * from @fd up to and including @max_fd are closed. + */ +int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) +{ + unsigned int cur_max; + struct task_struct *me = current; + struct files_struct *cur_fds = me->files, *fds = NULL; + + if (flags & ~CLOSE_RANGE_UNSHARE) + return -EINVAL; + + if (fd > max_fd) + return -EINVAL; + + rcu_read_lock(); + cur_max = files_fdtable(cur_fds)->max_fds; + rcu_read_unlock(); + + /* cap to last valid index into fdtable */ + cur_max--; + + if (flags & CLOSE_RANGE_UNSHARE) { + int ret; + unsigned int max_unshare_fds = NR_OPEN_MAX; + + /* + * If the requested range is greater than the current maximum, + * we're closing everything so only copy all file descriptors + * beneath the lowest file descriptor. + */ + if (max_fd >= cur_max) + max_unshare_fds = fd; + + ret = unshare_fd(CLONE_FILES, max_unshare_fds, &fds); + if (ret) + return ret; + + /* + * We used to share our file descriptor table, and have now + * created a private one, make sure we're using it below. + */ + if (fds) + swap(cur_fds, fds); + } + + max_fd = min(max_fd, cur_max); + while (fd <= max_fd) { + struct file *file; + + file = pick_file(cur_fds, fd++); + if (!file) + continue; + + filp_close(file, cur_fds); + cond_resched(); + } + + if (fds) { + /* + * We're done closing the files we were supposed to. Time to install + * the new file descriptor table and drop the old one. + */ + task_lock(me); + me->files = cur_fds; + task_unlock(me); + put_files_struct(fds); + } + + return 0; +} + /* * variant of __close_fd that gets a ref on the file for later fput. * The caller must ensure that filp_close() called on the file, and then @@ -931,6 +1035,62 @@ out_unlock: return err; } +/** + * __receive_fd() - Install received file into file descriptor table + * + * @fd: fd to install into (if negative, a new fd will be allocated) + * @file: struct file that was received from another process + * @ufd: __user pointer to write new fd number to + * @o_flags: the O_* flags to apply to the new fd entry + * + * Installs a received file into the file descriptor table, with appropriate + * checks and count updates. Optionally writes the fd number to userspace, if + * @ufd is non-NULL. + * + * This helper handles its own reference counting of the incoming + * struct file. + * + * Returns newly install fd or -ve on error. + */ +int __receive_fd(int fd, struct file *file, int __user *ufd, unsigned int o_flags) +{ + int new_fd; + int error; + + error = security_file_receive(file); + if (error) + return error; + + if (fd < 0) { + new_fd = get_unused_fd_flags(o_flags); + if (new_fd < 0) + return new_fd; + } else { + new_fd = fd; + } + + if (ufd) { + error = put_user(new_fd, ufd); + if (error) { + if (fd < 0) + put_unused_fd(new_fd); + return error; + } + } + + if (fd < 0) { + fd_install(new_fd, get_file(file)); + } else { + error = replace_fd(new_fd, file, o_flags); + if (error) + return error; + } + + /* Bump the sock usage counts, if any. */ + __receive_sock(file); + return new_fd; +} + static int ksys_dup3(unsigned int oldfd, unsigned int newfd, int flags) { int err = -EBADF; @@ -985,7 +1145,7 @@ SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd) return ksys_dup3(oldfd, newfd, 0); } -int ksys_dup(unsigned int fildes) +SYSCALL_DEFINE1(dup, unsigned int, fildes) { int ret = -EBADF; struct file *file = fget_raw(fildes); @@ -1000,11 +1160,6 @@ int ksys_dup(unsigned int fildes) return ret; } -SYSCALL_DEFINE1(dup, unsigned int, fildes) -{ - return ksys_dup(fildes); -} - int f_dupfd(unsigned int from, struct file *file, unsigned flags) { int err; |