From 8d9117009dd690f647a66912f429c96335069907 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 13 May 2025 13:23:31 +0200 Subject: [PATCH] fuse: don't allow signals to interrupt getdents copying When getting the directory contents, the entries are first fetched to a kernel buffer, then they are copied to userspace with dir_emit(). This second phase is non-blocking as long as the userspace buffer is not paged out, making it interruptible makes zero sense. Overload d_type as flags, since it only uses 4 bits from 32. Reviewed-by: Bernd Schubert Signed-off-by: Miklos Szeredi Link: https://lore.kernel.org/20250513112335.1473177-1-mszeredi@redhat.com Signed-off-by: Christian Brauner --- fs/fuse/readdir.c | 4 ++-- fs/readdir.c | 18 +++++++++++++++--- include/linux/fs.h | 3 +++ 3 files changed, 20 insertions(+), 5 deletions(-) diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c index 17ce9636a2b1..edcd6f18a8a8 100644 --- a/fs/fuse/readdir.c +++ b/fs/fuse/readdir.c @@ -120,7 +120,7 @@ static bool fuse_emit(struct file *file, struct dir_context *ctx, fuse_add_dirent_to_cache(file, dirent, ctx->pos); return dir_emit(ctx, dirent->name, dirent->namelen, dirent->ino, - dirent->type); + dirent->type | FILLDIR_FLAG_NOINTR); } static int parse_dirfile(char *buf, size_t nbytes, struct file *file, @@ -419,7 +419,7 @@ static enum fuse_parse_result fuse_parse_cache(struct fuse_file *ff, if (ff->readdir.pos == ctx->pos) { res = FOUND_SOME; if (!dir_emit(ctx, dirent->name, dirent->namelen, - dirent->ino, dirent->type)) + dirent->ino, dirent->type | FILLDIR_FLAG_NOINTR)) return FOUND_ALL; ctx->pos = dirent->off; } diff --git a/fs/readdir.c b/fs/readdir.c index 0038efda417b..857d402bc531 100644 --- a/fs/readdir.c +++ b/fs/readdir.c @@ -266,6 +266,10 @@ static bool filldir(struct dir_context *ctx, const char *name, int namlen, int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2, sizeof(long)); int prev_reclen; + unsigned int flags = d_type; + + BUILD_BUG_ON(FILLDIR_FLAG_NOINTR & S_DT_MASK); + d_type &= S_DT_MASK; buf->error = verify_dirent_name(name, namlen); if (unlikely(buf->error)) @@ -279,7 +283,7 @@ static bool filldir(struct dir_context *ctx, const char *name, int namlen, return false; } prev_reclen = buf->prev_reclen; - if (prev_reclen && signal_pending(current)) + if (!(flags & FILLDIR_FLAG_NOINTR) && prev_reclen && signal_pending(current)) return false; dirent = buf->current_dir; prev = (void __user *) dirent - prev_reclen; @@ -351,6 +355,10 @@ static bool filldir64(struct dir_context *ctx, const char *name, int namlen, int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1, sizeof(u64)); int prev_reclen; + unsigned int flags = d_type; + + BUILD_BUG_ON(FILLDIR_FLAG_NOINTR & S_DT_MASK); + d_type &= S_DT_MASK; buf->error = verify_dirent_name(name, namlen); if (unlikely(buf->error)) @@ -359,7 +367,7 @@ static bool filldir64(struct dir_context *ctx, const char *name, int namlen, if (reclen > buf->count) return false; prev_reclen = buf->prev_reclen; - if (prev_reclen && signal_pending(current)) + if (!(flags & FILLDIR_FLAG_NOINTR) && prev_reclen && signal_pending(current)) return false; dirent = buf->current_dir; prev = (void __user *)dirent - prev_reclen; @@ -513,6 +521,10 @@ static bool compat_filldir(struct dir_context *ctx, const char *name, int namlen int reclen = ALIGN(offsetof(struct compat_linux_dirent, d_name) + namlen + 2, sizeof(compat_long_t)); int prev_reclen; + unsigned int flags = d_type; + + BUILD_BUG_ON(FILLDIR_FLAG_NOINTR & S_DT_MASK); + d_type &= S_DT_MASK; buf->error = verify_dirent_name(name, namlen); if (unlikely(buf->error)) @@ -526,7 +538,7 @@ static bool compat_filldir(struct dir_context *ctx, const char *name, int namlen return false; } prev_reclen = buf->prev_reclen; - if (prev_reclen && signal_pending(current)) + if (!(flags & FILLDIR_FLAG_NOINTR) && prev_reclen && signal_pending(current)) return false; dirent = buf->current_dir; prev = (void __user *) dirent - prev_reclen; diff --git a/include/linux/fs.h b/include/linux/fs.h index cf7208500cee..c8b5af17060e 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2073,6 +2073,9 @@ struct dir_context { loff_t pos; }; +/* If OR-ed with d_type, pending signals are not checked */ +#define FILLDIR_FLAG_NOINTR 0x1000 + /* * These flags let !MMU mmap() govern direct device mapping vs immediate * copying more easily for MAP_PRIVATE, especially for ROM filesystems. -- 2.25.1