// SPDX-License-Identifier: GPL-2.0/* * linux/fs/seq_file.c * * helper functions for making synthetic files from sequences of records. * initial implementation -- AV, Oct 2001. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/cache.h>#include <linux/fs.h>#include <linux/export.h>#include <linux/hex.h>#include <linux/seq_file.h>#include <linux/vmalloc.h>#include <linux/slab.h>#include <linux/cred.h>#include <linux/mm.h>#include <linux/printk.h>#include <linux/string_helpers.h>#include <linux/uio.h> #include <linux/uaccess.h>#include <asm/page.h> static struct kmem_cache *seq_file_cache __ro_after_init; static void seq_set_overflow(struct seq_file *m){ m->count = m->size;} static void *seq_buf_alloc(unsigned long size){ if (unlikely(size > MAX_RW_COUNT)) return NULL; return kvmalloc(size, GFP_KERNEL_ACCOUNT);} /** * seq_open - initialize sequential file * @file: file we initialize * @op: method table describing the sequence * * seq_open() sets @file, associating it with a sequence described * by @op. @op->start() sets the iterator up and returns the first * element of sequence. @op->stop() shuts it down. @op->next() * returns the next element of sequence. @op->show() prints element * into the buffer. In case of error ->start() and ->next() return * ERR_PTR(error). In the end of sequence they return %NULL. ->show() * returns 0 in case of success and negative number in case of error. * Returning SEQ_SKIP means "discard this element and move on". * Note: seq_open() will allocate a struct seq_file and store its * pointer in @file->private_data. This pointer should not be modified. */int seq_open(struct file *file, const struct seq_operations *op){ struct seq_file *p; WARN_ON(file->private_data); p = kmem_cache_zalloc(seq_file_cache, GFP_KERNEL); if (!p) return -ENOMEM; file->private_data = p; mutex_init(&p->lock); p->op = op; // No refcounting: the lifetime of 'p' is constrained // to the lifetime of the file. p->file = file; /* * seq_files support lseek() and pread(). They do not implement * write() at all, but we clear FMODE_PWRITE here for historical * reasons. * * If a client of seq_files a) implements file.write() and b) wishes to * support pwrite() then that client will need to implement its own * file.open() which calls seq_open() and then sets FMODE_PWRITE. */ file->f_mode &= ~FMODE_PWRITE; return 0;}EXPORT_SYMBOL(seq_open); static int traverse(struct seq_file *m, loff_t offset){ loff_t pos = 0; int error = 0; void *p; m->index = 0; m->count = m->from = 0; if (!offset) return 0; if (!m->buf) { m->buf = seq_buf_alloc(m->size = PAGE_SIZE); if (!m->buf) return -ENOMEM; } p = m->op->start(m, &m->index); while (p) { error = PTR_ERR(p); if (IS_ERR(p)) break; error = m->op->show(m, p); if (error < 0) break; if (unlikely(error)) { error = 0; m->count = 0; } if (seq_has_overflowed(m)) goto Eoverflow; p = m->op->next(m, p, &m->index); if (pos + m->count > offset) { m->from = offset - pos; m->count -= m->from; break; } pos += m->count; m->count = 0; if (pos == offset) break; } m->op->stop(m, p); return error; Eoverflow: m->op->stop(m, p); kvfree(m->buf); m->count = 0; m->buf = seq_buf_alloc(m->size <<= 1); return !m->buf ? -ENOMEM : -EAGAIN;} /** * seq_read - ->read() method for sequential files. * @file: the file to read from * @buf: the buffer to read to * @size: the maximum number of bytes to read * @ppos: the current position in the file * * Ready-made ->f_op->read() */ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos){ struct iovec iov = { .iov_base = buf, .iov_len = size}; struct kiocb kiocb; struct iov_iter iter; ssize_t ret; init_sync_kiocb(&kiocb, file); iov_iter_init(&iter, ITER_DEST, &iov, 1, size); kiocb.ki_pos = *ppos; ret = seq_read_iter(&kiocb, &iter); *ppos = kiocb.ki_pos; return ret;}EXPORT_SYMBOL(seq_read); /* * Ready-made ->f_op->read_iter() */ssize_t seq_read_iter(struct kiocb *iocb, struct iov_iter *iter){ struct seq_file *m = iocb->ki_filp->private_data; size_t copied = 0; size_t n; void *p; int err = 0; if (!iov_iter_count(iter)) return 0; mutex_lock(&m->lock); /* * if request is to read from zero offset, reset iterator to first * record as it might have been already advanced by previous requests */ if (iocb->ki_pos == 0) { m->index = 0; m->count = 0; } /* Don't assume ki_pos is where we left it */ if (unlikely(iocb->ki_pos != m->read_pos)) { while ((err = traverse(m, iocb->ki_pos)) == -EAGAIN) ; if (err) { /* With prejudice... */ m->read_pos = 0; m->index = 0; m->count = 0; goto Done; } else { m->read_pos = iocb->ki_pos; } } /* grab buffer if we didn't have one */ if (!m->buf) { m->buf = seq_buf_alloc(m->size = PAGE_SIZE); if (!m->buf) goto Enomem; } // something left in the buffer - copy it out first if (m->count) { n = copy_to_iter(m->buf + m->from, m->count, iter); m->count -= n; m->from += n; copied += n; if (m->count) // hadn't managed to copy everything goto Done; } // get a non-empty record in the buffer m->from = 0; p = m->op->start(m, &m->index); while (1) { err = PTR_ERR(p); if (!p || IS_ERR(p)) // EOF or an error break; err = m->op->show(m, p); if (err < 0) // hard error break; if (unlikely(err)) // ->show() says "skip it" m->count = 0; if (unlikely(!m->count)) { // empty record p = m->op->next(m, p, &m->index); continue; } if (!seq_has_overflowed(m)) // got it goto Fill; // need a bigger buffer m->op->stop(m, p); kvfree(m->buf); m->count = 0; m->buf = seq_buf_alloc(m->size <<= 1); if (!m->buf) goto Enomem; p = m->op->start(m, &m->index); } // EOF or an error m->op->stop(m, p); m->count = 0; goto Done;Fill: // one non-empty record is in the buffer; if they want more, // try to fit more in, but in any case we need to advance // the iterator once for every record shown. while (1) { size_t offs = m->count; loff_t pos = m->index; p = m->op->next(m, p, &m->index); if (pos == m->index) { pr_info_ratelimited("buggy .next function %ps did not update position index\n", m->op->next); m->index++; } if (!p || IS_ERR(p)) // no next record for us break; if (m->count >= iov_iter_count(iter)) break; err = m->op->show(m, p); if (err > 0) { // ->show() says "skip it" m->count = offs; } else if (err || seq_has_overflowed(m)) { m->count = offs; break; } } m->op->stop(m, p); n = copy_to_iter(m->buf, m->count, iter); copied += n; m->count -= n; m->from = n;Done: if (unlikely(!copied)) { copied = m->count ? -EFAULT : err; } else { iocb->ki_pos += copied; m->read_pos += copied; } mutex_unlock(&m->lock); return copied;Enomem: err = -ENOMEM; goto Done;}EXPORT_SYMBOL(seq_read_iter); /** * seq_lseek - ->llseek() method for sequential files. * @file: the file in question * @offset: new position * @whence: 0 for absolute, 1 for relative position * * Ready-made ->f_op->llseek() */loff_t seq_lseek(struct file *file, loff_t offset, int whence){ struct seq_file *m = file->private_data; loff_t retval = -EINVAL; mutex_lock(&m->lock); switch (whence) { case SEEK_CUR: offset += file->f_pos; fallthrough; case SEEK_SET: if (offset < 0) break; retval = offset; if (offset != m->read_pos) { while ((retval = traverse(m, offset)) == -EAGAIN) ; if (retval) { /* with extreme prejudice... */ file->f_pos = 0; m->read_pos = 0; m->index = 0; m->count = 0; } else { m->read_pos = offset; retval = file->f_pos = offset; } } else { file->f_pos = offset; } } mutex_unlock(&m->lock); return retval;}EXPORT_SYMBOL(seq_lseek); /** * seq_release - free the structures associated with sequential file. * @inode: its inode * @file: file in question * * Frees the structures associated with sequential file; can be used * as ->f_op->release() if you don't have private data to destroy. */int seq_release(struct inode *inode, struct file *file){ struct seq_file *m = file->private_data; kvfree(m->buf); kmem_cache_free(seq_file_cache, m); return 0;}EXPORT_SYMBOL(seq_release); /** * seq_escape_mem - print data into buffer, escaping some characters * @m: target buffer * @src: source buffer * @len: size of source buffer * @flags: flags to pass to string_escape_mem() * @esc: set of characters that need escaping * * Puts data into buffer, replacing each occurrence of character from * given class (defined by @flags and @esc) with printable escaped sequence. * * Use seq_has_overflowed() to check for errors. */void seq_escape_mem(struct seq_file *m, const char *src, size_t len, unsigned int flags, const char *esc){ char *buf; size_t size = seq_get_buf(m, &buf); int ret; ret = string_escape_mem(src, len, buf, size, flags, esc); seq_commit(m, ret < size ? ret : -1);}EXPORT_SYMBOL(seq_escape_mem); void seq_vprintf(struct seq_file *m, const char *f, va_list args){ int len; if (m->count < m->size) { len = vsnprintf(m->buf + m->count, m->size - m->count, f, args); if (m->count + len < m->size) { m->count += len; return; } } seq_set_overflow(m);}EXPORT_SYMBOL(seq_vprintf); void seq_printf(struct seq_file *m, const char *f, ...){ va_list args; va_start(args, f); seq_vprintf(m, f, args); va_end(args);}EXPORT_SYMBOL(seq_printf); #ifdef CONFIG_BINARY_PRINTFvoid seq_bprintf(struct seq_file *m, const char *f, const u32 *binary){ int len; if (m->count < m->size) { len = bstr_printf(m->buf + m->count, m->size - m->count, f, binary); if (m->count + len < m->size) { m->count += len; return; } } seq_set_overflow(m);}EXPORT_SYMBOL(seq_bprintf);#endif /* CONFIG_BINARY_PRINTF */ /** * mangle_path - mangle and copy path to buffer beginning * @s: buffer start * @p: beginning of path in above buffer * @esc: set of characters that need escaping * * Copy the path from @p to @s, replacing each occurrence of character from * @esc with usual octal escape. * Returns pointer past last written character in @s, or NULL in case of * failure. */char *mangle_path(char *s, const char *p, const char *esc){ while (s <= p) { char c = *p++; if (!c) { return s; } else if (!strchr(esc, c)) { *s++ = c; } else if (s + 4 > p) { break; } else { *s++ = '\\'; *s++ = '0' + ((c & 0300) >> 6); *s++ = '0' + ((c & 070) >> 3); *s++ = '0' + (c & 07); } } return NULL;}EXPORT_SYMBOL(mangle_path); /** * seq_path - seq_file interface to print a pathname * @m: the seq_file handle * @path: the struct path to print * @esc: set of characters to escape in the output * * return the absolute path of 'path', as represented by the * dentry / mnt pair in the path parameter. */int seq_path(struct seq_file *m, const struct path *path, const char *esc){ char *buf; size_t size = seq_get_buf(m, &buf); int res = -1; if (size) { char *p = d_path(path, buf, size); if (!IS_ERR(p)) { char *end = mangle_path(buf, p, esc); if (end) res = end - buf; } } seq_commit(m, res); return res;}EXPORT_SYMBOL(seq_path); /** * seq_file_path - seq_file interface to print a pathname of a file * @m: the seq_file handle * @file: the struct file to print * @esc: set of characters to escape in the output * * return the absolute path to the file. */int seq_file_path(struct seq_file *m, struct file *file, const char *esc){Lines 1–500 of 1144. 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// SPDX-License-Identifier: GPL-2.0 /* * linux/fs/seq_file.c * * helper functions for making synthetic files from sequences of records. * initial implementation -- AV, Oct 2001. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/cache.h> #include <linux/fs.h> #include <linux/export.h> #include <linux/hex.h> #include <linux/seq_file.h> #include <linux/vmalloc.h> #include <linux/slab.h> #include <linux/cred.h> #include <linux/mm.h> #include <linux/printk.h> #include <linux/string_helpers.h> #include <linux/uio.h> #include <linux/uaccess.h> #include <asm/page.h> static struct kmem_cache *seq_file_cache __ro_after_init; static void seq_set_overflow(struct seq_file *m) { m->count = m->size; } static void *seq_buf_alloc(unsigned long size) { if (unlikely(size > MAX_RW_COUNT)) return NULL; return kvmalloc(size, GFP_KERNEL_ACCOUNT); } /** * seq_open - initialize sequential file * @file: file we initialize * @op: method table describing the sequence * * seq_open() sets @file, associating it with a sequence described * by @op. @op->start() sets the iterator up and returns the first * element of sequence. @op->stop() shuts it down. @op->next() * returns the next element of sequence. @op->show() prints element * into the buffer. In case of error ->start() and ->next() return * ERR_PTR(error). In the end of sequence they return %NULL. ->show() * returns 0 in case of success and negative number in case of error. * Returning SEQ_SKIP means "discard this element and move on". * Note: seq_open() will allocate a struct seq_file and store its * pointer in @file->private_data. This pointer should not be modified. */ int seq_open(struct file *file, const struct seq_operations *op) { struct seq_file *p; WARN_ON(file->private_data); p = kmem_cache_zalloc(seq_file_cache, GFP_KERNEL); if (!p) return -ENOMEM; file->private_data = p; mutex_init(&p->lock); p->op = op; // No refcounting: the lifetime of 'p' is constrained // to the lifetime of the file. p->file = file; /* * seq_files support lseek() and pread(). They do not implement * write() at all, but we clear FMODE_PWRITE here for historical * reasons. * * If a client of seq_files a) implements file.write() and b) wishes to * support pwrite() then that client will need to implement its own * file.open() which calls seq_open() and then sets FMODE_PWRITE. */ file->f_mode &= ~FMODE_PWRITE; return 0; } EXPORT_SYMBOL(seq_open); static int traverse(struct seq_file *m, loff_t offset) { loff_t pos = 0; int error = 0; void *p; m->index = 0; m->count = m->from = 0; if (!offset) return 0; if (!m->buf) { m->buf = seq_buf_alloc(m->size = PAGE_SIZE); if (!m->buf) return -ENOMEM; } p = m->op->start(m, &m->index); while (p) { error = PTR_ERR(p); if (IS_ERR(p)) break; error = m->op->show(m, p); if (error < 0) break; if (unlikely(error)) { error = 0; m->count = 0; } if (seq_has_overflowed(m)) goto Eoverflow; p = m->op->next(m, p, &m->index); if (pos + m->count > offset) { m->from = offset - pos; m->count -= m->from; break; } pos += m->count; m->count = 0; if (pos == offset) break; } m->op->stop(m, p); return error; Eoverflow: m->op->stop(m, p); kvfree(m->buf); m->count = 0; m->buf = seq_buf_alloc(m->size <<= 1); return !m->buf ? -ENOMEM : -EAGAIN; } /** * seq_read - ->read() method for sequential files. * @file: the file to read from * @buf: the buffer to read to * @size: the maximum number of bytes to read * @ppos: the current position in the file * * Ready-made ->f_op->read() */ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) { struct iovec iov = { .iov_base = buf, .iov_len = size}; struct kiocb kiocb; struct iov_iter iter; ssize_t ret; init_sync_kiocb(&kiocb, file); iov_iter_init(&iter, ITER_DEST, &iov, 1, size); kiocb.ki_pos = *ppos; ret = seq_read_iter(&kiocb, &iter); *ppos = kiocb.ki_pos; return ret; } EXPORT_SYMBOL(seq_read); /* * Ready-made ->f_op->read_iter() */ ssize_t seq_read_iter(struct kiocb *iocb, struct iov_iter *iter) { struct seq_file *m = iocb->ki_filp->private_data; size_t copied = 0; size_t n; void *p; int err = 0; if (!iov_iter_count(iter)) return 0; mutex_lock(&m->lock); /* * if request is to read from zero offset, reset iterator to first * record as it might have been already advanced by previous requests */ if (iocb->ki_pos == 0) { m->index = 0; m->count = 0; } /* Don't assume ki_pos is where we left it */ if (unlikely(iocb->ki_pos != m->read_pos)) { while ((err = traverse(m, iocb->ki_pos)) == -EAGAIN) ; if (err) { /* With prejudice... */ m->read_pos = 0; m->index = 0; m->count = 0; goto Done; } else { m->read_pos = iocb->ki_pos; } } /* grab buffer if we didn't have one */ if (!m->buf) { m->buf = seq_buf_alloc(m->size = PAGE_SIZE); if (!m->buf) goto Enomem; } // something left in the buffer - copy it out first if (m->count) { n = copy_to_iter(m->buf + m->from, m->count, iter); m->count -= n; m->from += n; copied += n; if (m->count) // hadn't managed to copy everything goto Done; } // get a non-empty record in the buffer m->from = 0; p = m->op->start(m, &m->index); while (1) { err = PTR_ERR(p); if (!p || IS_ERR(p)) // EOF or an error break; err = m->op->show(m, p); if (err < 0) // hard error break; if (unlikely(err)) // ->show() says "skip it" m->count = 0; if (unlikely(!m->count)) { // empty record p = m->op->next(m, p, &m->index); continue; } if (!seq_has_overflowed(m)) // got it goto Fill; // need a bigger buffer m->op->stop(m, p); kvfree(m->buf); m->count = 0; m->buf = seq_buf_alloc(m->size <<= 1); if (!m->buf) goto Enomem; p = m->op->start(m, &m->index); } // EOF or an error m->op->stop(m, p); m->count = 0; goto Done; Fill: // one non-empty record is in the buffer; if they want more, // try to fit more in, but in any case we need to advance // the iterator once for every record shown. while (1) { size_t offs = m->count; loff_t pos = m->index; p = m->op->next(m, p, &m->index); if (pos == m->index) { pr_info_ratelimited("buggy .next function %ps did not update position index\n", m->op->next); m->index++; } if (!p || IS_ERR(p)) // no next record for us break; if (m->count >= iov_iter_count(iter)) break; err = m->op->show(m, p); if (err > 0) { // ->show() says "skip it" m->count = offs; } else if (err || seq_has_overflowed(m)) { m->count = offs; break; } } m->op->stop(m, p); n = copy_to_iter(m->buf, m->count, iter); copied += n; m->count -= n; m->from = n; Done: if (unlikely(!copied)) { copied = m->count ? -EFAULT : err; } else { iocb->ki_pos += copied; m->read_pos += copied; } mutex_unlock(&m->lock); return copied; Enomem: err = -ENOMEM; goto Done; } EXPORT_SYMBOL(seq_read_iter); /** * seq_lseek - ->llseek() method for sequential files. * @file: the file in question * @offset: new position * @whence: 0 for absolute, 1 for relative position * * Ready-made ->f_op->llseek() */ loff_t seq_lseek(struct file *file, loff_t offset, int whence) { struct seq_file *m = file->private_data; loff_t retval = -EINVAL; mutex_lock(&m->lock); switch (whence) { case SEEK_CUR: offset += file->f_pos; fallthrough; case SEEK_SET: if (offset < 0) break; retval = offset; if (offset != m->read_pos) { while ((retval = traverse(m, offset)) == -EAGAIN) ; if (retval) { /* with extreme prejudice... */ file->f_pos = 0; m->read_pos = 0; m->index = 0; m->count = 0; } else { m->read_pos = offset; retval = file->f_pos = offset; } } else { file->f_pos = offset; } } mutex_unlock(&m->lock); return retval; } EXPORT_SYMBOL(seq_lseek); /** * seq_release - free the structures associated with sequential file. * @inode: its inode * @file: file in question * * Frees the structures associated with sequential file; can be used * as ->f_op->release() if you don't have private data to destroy. */ int seq_release(struct inode *inode, struct file *file) { struct seq_file *m = file->private_data; kvfree(m->buf); kmem_cache_free(seq_file_cache, m); return 0; } EXPORT_SYMBOL(seq_release); /** * seq_escape_mem - print data into buffer, escaping some characters * @m: target buffer * @src: source buffer * @len: size of source buffer * @flags: flags to pass to string_escape_mem() * @esc: set of characters that need escaping * * Puts data into buffer, replacing each occurrence of character from * given class (defined by @flags and @esc) with printable escaped sequence. * * Use seq_has_overflowed() to check for errors. */ void seq_escape_mem(struct seq_file *m, const char *src, size_t len, unsigned int flags, const char *esc) { char *buf; size_t size = seq_get_buf(m, &buf); int ret; ret = string_escape_mem(src, len, buf, size, flags, esc); seq_commit(m, ret < size ? ret : -1); } EXPORT_SYMBOL(seq_escape_mem); void seq_vprintf(struct seq_file *m, const char *f, va_list args) { int len; if (m->count < m->size) { len = vsnprintf(m->buf + m->count, m->size - m->count, f, args); if (m->count + len < m->size) { m->count += len; return; } } seq_set_overflow(m); } EXPORT_SYMBOL(seq_vprintf); void seq_printf(struct seq_file *m, const char *f, ...) { va_list args; va_start(args, f); seq_vprintf(m, f, args); va_end(args); } EXPORT_SYMBOL(seq_printf); #ifdef CONFIG_BINARY_PRINTF void seq_bprintf(struct seq_file *m, const char *f, const u32 *binary) { int len; if (m->count < m->size) { len = bstr_printf(m->buf + m->count, m->size - m->count, f, binary); if (m->count + len < m->size) { m->count += len; return; } } seq_set_overflow(m); } EXPORT_SYMBOL(seq_bprintf); #endif /* CONFIG_BINARY_PRINTF */ /** * mangle_path - mangle and copy path to buffer beginning * @s: buffer start * @p: beginning of path in above buffer * @esc: set of characters that need escaping * * Copy the path from @p to @s, replacing each occurrence of character from * @esc with usual octal escape. * Returns pointer past last written character in @s, or NULL in case of * failure. */ char *mangle_path(char *s, const char *p, const char *esc) { while (s <= p) { char c = *p++; if (!c) { return s; } else if (!strchr(esc, c)) { *s++ = c; } else if (s + 4 > p) { break; } else { *s++ = '\\'; *s++ = '0' + ((c & 0300) >> 6); *s++ = '0' + ((c & 070) >> 3); *s++ = '0' + (c & 07); } } return NULL; } EXPORT_SYMBOL(mangle_path); /** * seq_path - seq_file interface to print a pathname * @m: the seq_file handle * @path: the struct path to print * @esc: set of characters to escape in the output * * return the absolute path of 'path', as represented by the * dentry / mnt pair in the path parameter. */ int seq_path(struct seq_file *m, const struct path *path, const char *esc) { char *buf; size_t size = seq_get_buf(m, &buf); int res = -1; if (size) { char *p = d_path(path, buf, size); if (!IS_ERR(p)) { char *end = mangle_path(buf, p, esc); if (end) res = end - buf; } } seq_commit(m, res); return res; } EXPORT_SYMBOL(seq_path); /** * seq_file_path - seq_file interface to print a pathname of a file * @m: the seq_file handle * @file: the struct file to print * @esc: set of characters to escape in the output * * return the absolute path to the file. */ int seq_file_path(struct seq_file *m, struct file *file, const char *esc) {