diff options
| -rw-r--r-- | fs/file.c | 65 | ||||
| -rw-r--r-- | fs/open.c | 5 | ||||
| -rw-r--r-- | include/linux/fdtable.h | 8 | ||||
| -rw-r--r-- | include/uapi/linux/close_range.h | 9 | ||||
| -rw-r--r-- | kernel/fork.c | 11 |
5 files changed, 79 insertions, 19 deletions
diff --git a/fs/file.c b/fs/file.c index 1b8ff05e8311..340bc9569f9d 100644 --- a/fs/file.c +++ b/fs/file.c @@ -19,6 +19,7 @@ #include <linux/bitops.h> #include <linux/spinlock.h> #include <linux/rcupdate.h> +#include <linux/close_range.h> unsigned int sysctl_nr_open __read_mostly = 1024*1024; unsigned int sysctl_nr_open_min = BITS_PER_LONG; @@ -265,12 +266,22 @@ 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; @@ -297,7 +308,7 @@ 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. @@ -328,7 +339,7 @@ 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); @@ -665,32 +676,72 @@ EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ * This closes a range of file descriptors. All file descriptors * from @fd up to and including @max_fd are closed. */ -int __close_range(struct files_struct *files, unsigned fd, unsigned max_fd) +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(files)->max_fds; + 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(files, fd++); + file = pick_file(cur_fds, fd++); if (!file) continue; - filp_close(file, files); + 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; } diff --git a/fs/open.c b/fs/open.c index 073ea3c45347..5e62f18adc5b 100644 --- a/fs/open.c +++ b/fs/open.c @@ -1324,10 +1324,7 @@ SYSCALL_DEFINE1(close, unsigned int, fd) SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd, unsigned int, flags) { - if (flags) - return -EINVAL; - - return __close_range(current->files, fd, max_fd); + return __close_range(fd, max_fd, flags); } /* diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h index fcd07181a365..a32bf47c593e 100644 --- a/include/linux/fdtable.h +++ b/include/linux/fdtable.h @@ -22,6 +22,7 @@ * as this is the granularity returned by copy_fdset(). */ #define NR_OPEN_DEFAULT BITS_PER_LONG +#define NR_OPEN_MAX ~0U struct fdtable { unsigned int max_fds; @@ -109,7 +110,7 @@ struct files_struct *get_files_struct(struct task_struct *); void put_files_struct(struct files_struct *fs); void reset_files_struct(struct files_struct *); int unshare_files(struct files_struct **); -struct files_struct *dup_fd(struct files_struct *, int *) __latent_entropy; +struct files_struct *dup_fd(struct files_struct *, unsigned, int *) __latent_entropy; void do_close_on_exec(struct files_struct *); int iterate_fd(struct files_struct *, unsigned, int (*)(const void *, struct file *, unsigned), @@ -121,9 +122,10 @@ extern void __fd_install(struct files_struct *files, unsigned int fd, struct file *file); extern int __close_fd(struct files_struct *files, unsigned int fd); -extern int __close_range(struct files_struct *files, unsigned int fd, - unsigned int max_fd); +extern int __close_range(unsigned int fd, unsigned int max_fd, unsigned int flags); extern int __close_fd_get_file(unsigned int fd, struct file **res); +extern int unshare_fd(unsigned long unshare_flags, unsigned int max_fds, + struct files_struct **new_fdp); extern struct kmem_cache *files_cachep; diff --git a/include/uapi/linux/close_range.h b/include/uapi/linux/close_range.h new file mode 100644 index 000000000000..6928a9fdee3c --- /dev/null +++ b/include/uapi/linux/close_range.h @@ -0,0 +1,9 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef _UAPI_LINUX_CLOSE_RANGE_H +#define _UAPI_LINUX_CLOSE_RANGE_H + +/* Unshare the file descriptor table before closing file descriptors. */ +#define CLOSE_RANGE_UNSHARE (1U << 1) + +#endif /* _UAPI_LINUX_CLOSE_RANGE_H */ + diff --git a/kernel/fork.c b/kernel/fork.c index 142b23645d82..8948121c8454 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1474,7 +1474,7 @@ static int copy_files(unsigned long clone_flags, struct task_struct *tsk) goto out; } - newf = dup_fd(oldf, &error); + newf = dup_fd(oldf, NR_OPEN_MAX, &error); if (!newf) goto out; @@ -2907,14 +2907,15 @@ static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) /* * Unshare file descriptor table if it is being shared */ -static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) +int unshare_fd(unsigned long unshare_flags, unsigned int max_fds, + struct files_struct **new_fdp) { struct files_struct *fd = current->files; int error = 0; if ((unshare_flags & CLONE_FILES) && (fd && atomic_read(&fd->count) > 1)) { - *new_fdp = dup_fd(fd, &error); + *new_fdp = dup_fd(fd, max_fds, &error); if (!*new_fdp) return error; } @@ -2974,7 +2975,7 @@ int ksys_unshare(unsigned long unshare_flags) err = unshare_fs(unshare_flags, &new_fs); if (err) goto bad_unshare_out; - err = unshare_fd(unshare_flags, &new_fd); + err = unshare_fd(unshare_flags, NR_OPEN_MAX, &new_fd); if (err) goto bad_unshare_cleanup_fs; err = unshare_userns(unshare_flags, &new_cred); @@ -3063,7 +3064,7 @@ int unshare_files(struct files_struct **displaced) struct files_struct *copy = NULL; int error; - error = unshare_fd(CLONE_FILES, ©); + error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, ©); if (error || !copy) { *displaced = NULL; return error; |