cregit-Linux how code gets into the kernel

Release 4.18 fs/stat.c

Directory: fs
// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/stat.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/export.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/highuid.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/security.h>
#include <linux/cred.h>
#include <linux/syscalls.h>
#include <linux/pagemap.h>
#include <linux/compat.h>

#include <linux/uaccess.h>
#include <asm/unistd.h>

/**
 * generic_fillattr - Fill in the basic attributes from the inode struct
 * @inode: Inode to use as the source
 * @stat: Where to fill in the attributes
 *
 * Fill in the basic attributes in the kstat structure from data that's to be
 * found on the VFS inode structure.  This is the default if no getattr inode
 * operation is supplied.
 */

void generic_fillattr(struct inode *inode, struct kstat *stat) { stat->dev = inode->i_sb->s_dev; stat->ino = inode->i_ino; stat->mode = inode->i_mode; stat->nlink = inode->i_nlink; stat->uid = inode->i_uid; stat->gid = inode->i_gid; stat->rdev = inode->i_rdev; stat->size = i_size_read(inode); stat->atime = inode->i_atime; stat->mtime = inode->i_mtime; stat->ctime = inode->i_ctime; stat->blksize = i_blocksize(inode); stat->blocks = inode->i_blocks; if (IS_NOATIME(inode)) stat->result_mask &= ~STATX_ATIME; if (IS_AUTOMOUNT(inode)) stat->attributes |= STATX_ATTR_AUTOMOUNT; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro5436.00%220.00%
Linus Torvalds (pre-git)5335.33%440.00%
David Howells2718.00%110.00%
Linus Torvalds106.67%110.00%
Fabian Frederick32.00%110.00%
Andries E. Brouwer32.00%110.00%
Total150100.00%10100.00%

EXPORT_SYMBOL(generic_fillattr); /** * vfs_getattr_nosec - getattr without security checks * @path: file to get attributes from * @stat: structure to return attributes in * @request_mask: STATX_xxx flags indicating what the caller wants * @query_flags: Query mode (KSTAT_QUERY_FLAGS) * * Get attributes without calling security_inode_getattr. * * Currently the only caller other than vfs_getattr is internal to the * filehandle lookup code, which uses only the inode number and returns no * attributes to any user. Any other code probably wants vfs_getattr. */
int vfs_getattr_nosec(const struct path *path, struct kstat *stat, u32 request_mask, unsigned int query_flags) { struct inode *inode = d_backing_inode(path->dentry); memset(stat, 0, sizeof(*stat)); stat->result_mask |= STATX_BASIC_STATS; request_mask &= STATX_ALL; query_flags &= KSTAT_QUERY_FLAGS; if (inode->i_op->getattr) return inode->i_op->getattr(path, stat, request_mask, query_flags); generic_fillattr(inode, stat); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro4546.88%228.57%
David Howells4243.75%228.57%
Linus Torvalds (pre-git)88.33%228.57%
J. Bruce Fields11.04%114.29%
Total96100.00%7100.00%

EXPORT_SYMBOL(vfs_getattr_nosec); /* * vfs_getattr - Get the enhanced basic attributes of a file * @path: The file of interest * @stat: Where to return the statistics * @request_mask: STATX_xxx flags indicating what the caller wants * @query_flags: Query mode (KSTAT_QUERY_FLAGS) * * Ask the filesystem for a file's attributes. The caller must indicate in * request_mask and query_flags to indicate what they want. * * If the file is remote, the filesystem can be forced to update the attributes * from the backing store by passing AT_STATX_FORCE_SYNC in query_flags or can * suppress the update by passing AT_STATX_DONT_SYNC. * * Bits must have been set in request_mask to indicate which attributes the * caller wants retrieving. Any such attribute not requested may be returned * anyway, but the value may be approximate, and, if remote, may not have been * synchronised with the server. * * 0 will be returned on success, and a -ve error code if unsuccessful. */
int vfs_getattr(const struct path *path, struct kstat *stat, u32 request_mask, unsigned int query_flags) { int retval; retval = security_inode_getattr(path); if (retval) return retval; return vfs_getattr_nosec(path, stat, request_mask, query_flags); }

Contributors

PersonTokensPropCommitsCommitProp
J. Bruce Fields4076.92%150.00%
David Howells1223.08%150.00%
Total52100.00%2100.00%

EXPORT_SYMBOL(vfs_getattr); /** * vfs_statx_fd - Get the enhanced basic attributes by file descriptor * @fd: The file descriptor referring to the file of interest * @stat: The result structure to fill in. * @request_mask: STATX_xxx flags indicating what the caller wants * @query_flags: Query mode (KSTAT_QUERY_FLAGS) * * This function is a wrapper around vfs_getattr(). The main difference is * that it uses a file descriptor to determine the file location. * * 0 will be returned on success, and a -ve error code if unsuccessful. */
int vfs_statx_fd(unsigned int fd, struct kstat *stat, u32 request_mask, unsigned int query_flags) { struct fd f; int error = -EBADF; if (query_flags & ~KSTAT_QUERY_FLAGS) return -EINVAL; f = fdget_raw(fd); if (f.file) { error = vfs_getattr(&f.file->f_path, stat, request_mask, query_flags); fdput(f); } return error; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)2934.94%642.86%
Eric Biggers1821.69%17.14%
Al Viro1214.46%428.57%
David Howells1214.46%17.14%
Christoph Hellwig1113.25%17.14%
Ulrich Drepper11.20%17.14%
Total83100.00%14100.00%

EXPORT_SYMBOL(vfs_statx_fd); /** * vfs_statx - Get basic and extra attributes by filename * @dfd: A file descriptor representing the base dir for a relative filename * @filename: The name of the file of interest * @flags: Flags to control the query * @stat: The result structure to fill in. * @request_mask: STATX_xxx flags indicating what the caller wants * * This function is a wrapper around vfs_getattr(). The main difference is * that it uses a filename and base directory to determine the file location. * Additionally, the use of AT_SYMLINK_NOFOLLOW in flags will prevent a symlink * at the given name from being referenced. * * 0 will be returned on success, and a -ve error code if unsuccessful. */
int vfs_statx(int dfd, const char __user *filename, int flags, struct kstat *stat, u32 request_mask) { struct path path; int error = -EINVAL; unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT; if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT | AT_EMPTY_PATH | KSTAT_QUERY_FLAGS)) != 0) return -EINVAL; if (flags & AT_SYMLINK_NOFOLLOW) lookup_flags &= ~LOOKUP_FOLLOW; if (flags & AT_NO_AUTOMOUNT) lookup_flags &= ~LOOKUP_AUTOMOUNT; if (flags & AT_EMPTY_PATH) lookup_flags |= LOOKUP_EMPTY; retry: error = user_path_at(dfd, filename, lookup_flags, &path); if (error) goto out; error = vfs_getattr(&path, stat, request_mask, flags); path_put(&path); if (retry_estale(error, lookup_flags)) { lookup_flags |= LOOKUP_REVAL; goto retry; } out: return error; }

Contributors

PersonTokensPropCommitsCommitProp
David Howells4326.22%315.79%
Christoph Hellwig3420.73%15.26%
Linus Torvalds (pre-git)2917.68%526.32%
Al Viro2716.46%526.32%
Jeff Layton2112.80%15.26%
Ulrich Drepper63.66%15.26%
Jan Blunck31.83%210.53%
Linus Torvalds10.61%15.26%
Total164100.00%19100.00%

EXPORT_SYMBOL(vfs_statx); #ifdef __ARCH_WANT_OLD_STAT /* * For backward compatibility? Maybe this should be moved * into arch/i386 instead? */
static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf) { static int warncount = 5; struct __old_kernel_stat tmp; if (warncount > 0) { warncount--; printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n", current->comm); } else if (warncount < 0) { /* it's laughable, but... */ warncount = 0; } memset(&tmp, 0, sizeof(struct __old_kernel_stat)); tmp.st_dev = old_encode_dev(stat->dev); tmp.st_ino = stat->ino; if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino) return -EOVERFLOW; tmp.st_mode = stat->mode; tmp.st_nlink = stat->nlink; if (tmp.st_nlink != stat->nlink) return -EOVERFLOW; SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid)); SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid)); tmp.st_rdev = old_encode_dev(stat->rdev); #if BITS_PER_LONG == 32 if (stat->size > MAX_NON_LFS) return -EOVERFLOW; #endif tmp.st_size = stat->size; tmp.st_atime = stat->atime.tv_sec; tmp.st_mtime = stat->mtime.tv_sec; tmp.st_ctime = stat->ctime.tv_sec; return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro15857.66%210.53%
Linus Torvalds (pre-git)3512.77%1052.63%
David Howells2810.22%15.26%
Chris Wedgwood145.11%15.26%
Alan Cox145.11%15.26%
Andi Kleen124.38%210.53%
Eric W. Biedermann124.38%15.26%
Linus Torvalds10.36%15.26%
Total274100.00%19100.00%

SYSCALL_DEFINE2(stat, const char __user *, filename, struct __old_kernel_stat __user *, statbuf) { struct kstat stat; int error; error = vfs_stat(filename, &stat); if (error) return error; return cp_old_stat(&stat, statbuf); } SYSCALL_DEFINE2(lstat, const char __user *, filename, struct __old_kernel_stat __user *, statbuf) { struct kstat stat; int error; error = vfs_lstat(filename, &stat); if (error) return error; return cp_old_stat(&stat, statbuf); } SYSCALL_DEFINE2(fstat, unsigned int, fd, struct __old_kernel_stat __user *, statbuf) { struct kstat stat; int error = vfs_fstat(fd, &stat); if (!error) error = cp_old_stat(&stat, statbuf); return error; } #endif /* __ARCH_WANT_OLD_STAT */ #if BITS_PER_LONG == 32 # define choose_32_64(a,b) a #else # define choose_32_64(a,b) b #endif #define valid_dev(x) choose_32_64(old_valid_dev(x),true) #define encode_dev(x) choose_32_64(old_encode_dev,new_encode_dev)(x) #ifndef INIT_STRUCT_STAT_PADDING # define INIT_STRUCT_STAT_PADDING(st) memset(&st, 0, sizeof(st)) #endif
static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf) { struct stat tmp; if (!valid_dev(stat->dev) || !valid_dev(stat->rdev)) return -EOVERFLOW; #if BITS_PER_LONG == 32 if (stat->size > MAX_NON_LFS) return -EOVERFLOW; #endif INIT_STRUCT_STAT_PADDING(tmp); tmp.st_dev = encode_dev(stat->dev); tmp.st_ino = stat->ino; if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino) return -EOVERFLOW; tmp.st_mode = stat->mode; tmp.st_nlink = stat->nlink; if (tmp.st_nlink != stat->nlink) return -EOVERFLOW; SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid)); SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid)); tmp.st_rdev = encode_dev(stat->rdev); tmp.st_size = stat->size; tmp.st_atime = stat->atime.tv_sec; tmp.st_mtime = stat->mtime.tv_sec; tmp.st_ctime = stat->ctime.tv_sec; #ifdef STAT_HAVE_NSEC tmp.st_atime_nsec = stat->atime.tv_nsec; tmp.st_mtime_nsec = stat->mtime.tv_nsec; tmp.st_ctime_nsec = stat->ctime.tv_nsec; #endif tmp.st_blocks = stat->blocks; tmp.st_blksize = stat->blksize; return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro17558.92%215.38%
Andi Kleen4715.82%215.38%
David Howells289.43%17.69%
Linus Torvalds144.71%323.08%
Chris Wedgwood144.71%17.69%
Eric W. Biedermann124.04%17.69%
Linus Torvalds (pre-git)72.36%323.08%
Total297100.00%13100.00%

SYSCALL_DEFINE2(newstat, const char __user *, filename, struct stat __user *, statbuf) { struct kstat stat; int error = vfs_stat(filename, &stat); if (error) return error; return cp_new_stat(&stat, statbuf); } SYSCALL_DEFINE2(newlstat, const char __user *, filename, struct stat __user *, statbuf) { struct kstat stat; int error; error = vfs_lstat(filename, &stat); if (error) return error; return cp_new_stat(&stat, statbuf); } #if !defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_SYS_NEWFSTATAT) SYSCALL_DEFINE4(newfstatat, int, dfd, const char __user *, filename, struct stat __user *, statbuf, int, flag) { struct kstat stat; int error; error = vfs_fstatat(dfd, filename, &stat, flag); if (error) return error; return cp_new_stat(&stat, statbuf); } #endif SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf) { struct kstat stat; int error = vfs_fstat(fd, &stat); if (!error) error = cp_new_stat(&stat, statbuf); return error; }
static int do_readlinkat(int dfd, const char __user *pathname, char __user *buf, int bufsiz) { struct path path; int error; int empty = 0; unsigned int lookup_flags = LOOKUP_EMPTY; if (bufsiz <= 0) return -EINVAL; retry: error = user_path_at_empty(dfd, pathname, lookup_flags, &path, &empty); if (!error) { struct inode *inode = d_backing_inode(path.dentry); error = empty ? -ENOENT : -EINVAL; /* * AFS mountpoints allow readlink(2) but are not symlinks */ if (d_is_symlink(path.dentry) || inode->i_op->readlink) { error = security_inode_readlink(path.dentry); if (!error) { touch_atime(&path); error = vfs_readlink(path.dentry, buf, bufsiz); } } path_put(&path); if (retry_estale(error, lookup_flags)) { lookup_flags |= LOOKUP_REVAL; goto retry; } } return error; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)7340.78%939.13%
Jeff Layton2715.08%14.35%
Dominik Brodowski2111.73%14.35%
Andy Whitcroft147.82%14.35%
Jan Blunck95.03%28.70%
Miklos Szeredi95.03%14.35%
Stephen D. Smalley84.47%14.35%
Al Viro63.35%313.04%
Greg Kroah-Hartman63.35%28.70%
David Howells31.68%14.35%
Ulrich Drepper31.68%14.35%
Total179100.00%23100.00%

SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname, char __user *, buf, int, bufsiz) { return do_readlinkat(dfd, pathname, buf, bufsiz); } SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf, int, bufsiz) { return do_readlinkat(AT_FDCWD, path, buf, bufsiz); } /* ---------- LFS-64 ----------- */ #if defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_COMPAT_STAT64) #ifndef INIT_STRUCT_STAT64_PADDING # define INIT_STRUCT_STAT64_PADDING(st) memset(&st, 0, sizeof(st)) #endif
static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf) { struct stat64 tmp; INIT_STRUCT_STAT64_PADDING(tmp); #ifdef CONFIG_MIPS /* mips has weird padding, so we don't get 64 bits there */ tmp.st_dev = new_encode_dev(stat->dev); tmp.st_rdev = new_encode_dev(stat->rdev); #else tmp.st_dev = huge_encode_dev(stat->dev); tmp.st_rdev = huge_encode_dev(stat->rdev); #endif tmp.st_ino = stat->ino; if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino) return -EOVERFLOW; #ifdef STAT64_HAS_BROKEN_ST_INO tmp.__st_ino = stat->ino; #endif tmp.st_mode = stat->mode; tmp.st_nlink = stat->nlink; tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid); tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid); tmp.st_atime = stat->atime.tv_sec; tmp.st_atime_nsec = stat->atime.tv_nsec; tmp.st_mtime = stat->mtime.tv_sec; tmp.st_mtime_nsec = stat->mtime.tv_nsec; tmp.st_ctime = stat->ctime.tv_sec; tmp.st_ctime_nsec = stat->ctime.tv_nsec; tmp.st_size = stat->size; tmp.st_blocks = stat->blocks; tmp.st_blksize = stat->blksize; return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro10136.86%330.00%
Linus Torvalds (pre-git)9534.67%220.00%
Andi Kleen3613.14%110.00%
David Howells2810.22%110.00%
Eric W. Biedermann124.38%110.00%
Linus Torvalds20.73%220.00%
Total274100.00%10100.00%

SYSCALL_DEFINE2(stat64, const char __user *, filename, struct stat64 __user *, statbuf) { struct kstat stat; int error = vfs_stat(filename, &stat); if (!error) error = cp_new_stat64(&stat, statbuf); return error; } SYSCALL_DEFINE2(lstat64, const char __user *, filename, struct stat64 __user *, statbuf) { struct kstat stat; int error = vfs_lstat(filename, &stat); if (!error) error = cp_new_stat64(&stat, statbuf); return error; } SYSCALL_DEFINE2(fstat64, unsigned long, fd, struct stat64 __user *, statbuf) { struct kstat stat; int error = vfs_fstat(fd, &stat); if (!error) error = cp_new_stat64(&stat, statbuf); return error; } SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename, struct stat64 __user *, statbuf, int, flag) { struct kstat stat; int error; error = vfs_fstatat(dfd, filename, &stat, flag); if (error) return error; return cp_new_stat64(&stat, statbuf); } #endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */
static noinline_for_stack int cp_statx(const struct kstat *stat, struct statx __user *buffer) { struct statx tmp; memset(&tmp, 0, sizeof(tmp)); tmp.stx_mask = stat->result_mask; tmp.stx_blksize = stat->blksize; tmp.stx_attributes = stat->attributes; tmp.stx_nlink = stat->nlink; tmp.stx_uid = from_kuid_munged(current_user_ns(), stat->uid); tmp.stx_gid = from_kgid_munged(current_user_ns(), stat->gid); tmp.stx_mode = stat->mode; tmp.stx_ino = stat->ino; tmp.stx_size = stat->size; tmp.stx_blocks = stat->blocks; tmp.stx_attributes_mask = stat->attributes_mask; tmp.stx_atime.tv_sec = stat->atime.tv_sec; tmp.stx_atime.tv_nsec = stat->atime.tv_nsec; tmp.stx_btime.tv_sec = stat->btime.tv_sec; tmp.stx_btime.tv_nsec = stat->btime.tv_nsec; tmp.stx_ctime.tv_sec = stat->ctime.tv_sec; tmp.stx_ctime.tv_nsec = stat->ctime.tv_nsec; tmp.stx_mtime.tv_sec = stat->mtime.tv_sec; tmp.stx_mtime.tv_nsec = stat->mtime.tv_nsec; tmp.stx_rdev_major = MAJOR(stat->rdev); tmp.stx_rdev_minor = MINOR(stat->rdev); tmp.stx_dev_major = MAJOR(stat->dev); tmp.stx_dev_minor = MINOR(stat->dev); return copy_to_user(buffer, &tmp, sizeof(tmp)) ? -EFAULT : 0; }

Contributors

PersonTokensPropCommitsCommitProp
Eric Biggers19666.44%133.33%
David Howells9933.56%266.67%
Total295100.00%3100.00%

/** * sys_statx - System call to get enhanced stats * @dfd: Base directory to pathwalk from *or* fd to stat. * @filename: File to stat or "" with AT_EMPTY_PATH * @flags: AT_* flags to control pathwalk. * @mask: Parts of statx struct actually required. * @buffer: Result buffer. * * Note that fstat() can be emulated by setting dfd to the fd of interest, * supplying "" as the filename and setting AT_EMPTY_PATH in the flags. */ SYSCALL_DEFINE5(statx, int, dfd, const char __user *, filename, unsigned, flags, unsigned int, mask, struct statx __user *, buffer) { struct kstat stat; int error; if (mask & STATX__RESERVED) return -EINVAL; if ((flags & AT_STATX_SYNC_TYPE) == AT_STATX_SYNC_TYPE) return -EINVAL; error = vfs_statx(dfd, filename, flags, &stat, mask); if (error) return error; return cp_statx(&stat, buffer); } #ifdef CONFIG_COMPAT
static int cp_compat_stat(struct kstat *stat, struct compat_stat __user *ubuf) { struct compat_stat tmp; if (!old_valid_dev(stat->dev) || !old_valid_dev(stat->rdev)) return -EOVERFLOW; memset(&tmp, 0, sizeof(tmp)); tmp.st_dev = old_encode_dev(stat->dev); tmp.st_ino = stat->ino; if (sizeof(tmp.st_ino)