| Message ID | 20231110151928.2667204-1-wozizhi@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [next,V3] proc: support file->f_pos checking in mem_lseek | expand |
On Fri, Nov 10, 2023 at 11:19:28PM +0800, Zizhi Wo wrote: > From: WoZ1zh1 <wozizhi@huawei.com> > > In mem_lseek, file->f_pos may overflow. And it's not a problem that > mem_open set file mode with FMODE_UNSIGNED_OFFSET(memory_lseek). However, > another file use mem_lseek do lseek can have not FMODE_UNSIGNED_OFFSET > (kpageflags_proc_ops/proc_pagemap_operations...), so in order to prevent > file->f_pos updated to an abnormal number, fix it by checking overflow and > FMODE_UNSIGNED_OFFSET. 1) How is that different from the previous version? 2) Would FMODE_UNSIGNED_OFFSET be wrong for those files? If not, why not?
On 11/10, Zizhi Wo wrote: > > From: WoZ1zh1 <wozizhi@huawei.com> > > In mem_lseek, file->f_pos may overflow. And it's not a problem that > mem_open set file mode with FMODE_UNSIGNED_OFFSET(memory_lseek). However, > another file use mem_lseek do lseek can have not FMODE_UNSIGNED_OFFSET > (kpageflags_proc_ops/proc_pagemap_operations...), so in order to prevent > file->f_pos updated to an abnormal number, fix it by checking overflow and > FMODE_UNSIGNED_OFFSET. I am wondering if we can do something like the patch below instead... but I agree that the "proc_lseek == mem_lseek" in proc_reg_open() looks ugly. Oleg. diff --git a/fs/proc/inode.c b/fs/proc/inode.c index 532dc9d240f7..af7e6b1e17fe 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -496,6 +496,8 @@ static int proc_reg_open(struct inode *inode, struct file *file) if (!pde->proc_ops->proc_lseek) file->f_mode &= ~FMODE_LSEEK; + else if (pde->proc_ops->proc_lseek == mem_lseek) + file->f_mode |= FMODE_UNSIGNED_OFFSET; if (pde_is_permanent(pde)) { open = pde->proc_ops->proc_open; diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 3dd5be96691b..729b28ad1a96 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1748,7 +1748,9 @@ static int pagemap_open(struct inode *inode, struct file *file) mm = proc_mem_open(inode, PTRACE_MODE_READ); if (IS_ERR(mm)) return PTR_ERR(mm); + file->private_data = mm; + file->f_mode |= FMODE_UNSIGNED_OFFSET; return 0; }
diff --git a/fs/proc/base.c b/fs/proc/base.c index dd31e3b6bf77..20f5fcf6b73e 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -903,18 +903,33 @@ static ssize_t mem_write(struct file *file, const char __user *buf, loff_t mem_lseek(struct file *file, loff_t offset, int orig) { + loff_t ret = 0; + + spin_lock(&file->f_lock); switch (orig) { - case 0: - file->f_pos = offset; - break; - case 1: - file->f_pos += offset; + case SEEK_CUR: + offset += file->f_pos; + fallthrough; + case SEEK_SET: + /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */ + if ((unsigned long long)offset >= -MAX_ERRNO) + ret = -EOVERFLOW; break; default: - return -EINVAL; + ret = -EINVAL; } - force_successful_syscall_return(); - return file->f_pos; + if (!ret) { + if (offset < 0 && !(unsigned_offsets(file))) { + ret = -EINVAL; + } else { + file->f_pos = offset; + ret = file->f_pos; + force_successful_syscall_return(); + } + } + + spin_unlock(&file->f_lock); + return ret; } static int mem_release(struct inode *inode, struct file *file) diff --git a/fs/read_write.c b/fs/read_write.c index 4771701c896b..2f456d5a1df5 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -34,11 +34,6 @@ const struct file_operations generic_ro_fops = { EXPORT_SYMBOL(generic_ro_fops); -static inline bool unsigned_offsets(struct file *file) -{ - return file->f_mode & FMODE_UNSIGNED_OFFSET; -} - /** * vfs_setpos - update the file offset for lseek * @file: file structure in question diff --git a/include/linux/fs.h b/include/linux/fs.h index 98b7a7a8c42e..dde0756d2350 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2994,7 +2994,10 @@ extern ssize_t iter_file_splice_write(struct pipe_inode_info *, extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, loff_t *opos, size_t len, unsigned int flags); - +static inline bool unsigned_offsets(struct file *file) +{ + return file->f_mode & FMODE_UNSIGNED_OFFSET; +} extern void file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping); extern loff_t noop_llseek(struct file *file, loff_t offset, int whence);