From 3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 2 Sep 2026 15:31:14 -0700 Subject: treewide: refresh kmalloc_obj() conversions This is another run of the Coccinelle script for converting kmalloc() family of allocations to kmalloc_obj() via the existing rules in scripts/coccinelle/api/kmalloc_objs.cocci This catches both the set of kmalloc() uses added since the first kmalloc_obj() conversions in v7.0 and adds a large group missed in the first pass due to Coccinelle not interacting well with the cleanup.h scoped_...() family of macros[1]. I worked around this with spatch's "--macro-file" argument to a file with all the scoped_...() macros mapped to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control flow indicator I could find. Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc, riscv, and s390 with no new warnings. Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1] Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2] Signed-off-by: Kees Cook --- fs/open.c | 1634 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 1634 insertions(+) create mode 100644 fs/open.c (limited to 'fs/open.c') diff --git a/fs/open.c b/fs/open.c new file mode 100644 index 000000000..6b1c14e68 --- /dev/null +++ b/fs/open.c @@ -0,0 +1,1634 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/fs/open.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "internal.h" + +int do_truncate(struct mnt_idmap *idmap, struct dentry *dentry, + loff_t length, unsigned int time_attrs, struct file *filp) +{ + int ret; + struct iattr newattrs; + + /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */ + if (length < 0) + return -EINVAL; + + newattrs.ia_size = length; + newattrs.ia_valid = ATTR_SIZE | time_attrs; + if (filp) { + newattrs.ia_file = filp; + newattrs.ia_valid |= ATTR_FILE; + } + + /* Remove suid, sgid, and file capabilities on truncate too */ + ret = dentry_needs_remove_privs(idmap, dentry); + if (ret < 0) + return ret; + if (ret) + newattrs.ia_valid |= ret | ATTR_FORCE; + + ret = inode_lock_killable(dentry->d_inode); + if (ret) + return ret; + + /* Note any delegations or leases have already been broken: */ + ret = notify_change(idmap, dentry, &newattrs, NULL); + inode_unlock(dentry->d_inode); + return ret; +} + +int vfs_truncate(const struct path *path, loff_t length) +{ + struct mnt_idmap *idmap; + struct inode *inode; + int error; + + inode = path->dentry->d_inode; + + /* For directories it's -EISDIR, for other non-regulars - -EINVAL */ + if (S_ISDIR(inode->i_mode)) + return -EISDIR; + if (!S_ISREG(inode->i_mode)) + return -EINVAL; + + idmap = mnt_idmap(path->mnt); + error = inode_permission(idmap, inode, MAY_WRITE); + if (error) + return error; + + error = fsnotify_truncate_perm(path, length); + if (error) + return error; + + error = mnt_want_write(path->mnt); + if (error) + return error; + + error = -EPERM; + if (IS_APPEND(inode)) + goto mnt_drop_write_and_out; + + error = get_write_access(inode); + if (error) + goto mnt_drop_write_and_out; + + /* + * Make sure that there are no leases. get_write_access() protects + * against the truncate racing with a lease-granting setlease(). + */ + error = break_lease(inode, O_WRONLY); + if (error) + goto put_write_and_out; + + error = security_path_truncate(path); + if (!error) + error = do_truncate(idmap, path->dentry, length, 0, NULL); + +put_write_and_out: + put_write_access(inode); +mnt_drop_write_and_out: + mnt_drop_write(path->mnt); + + return error; +} +EXPORT_SYMBOL_GPL(vfs_truncate); + +int ksys_truncate(const char __user *pathname, loff_t length) +{ + unsigned int lookup_flags = LOOKUP_FOLLOW; + struct path path; + int error; + + if (length < 0) /* sorry, but loff_t says... */ + return -EINVAL; + + CLASS(filename, name)(pathname); +retry: + error = filename_lookup(AT_FDCWD, name, lookup_flags, &path, NULL); + if (!error) { + error = vfs_truncate(&path, length); + path_put(&path); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } + } + return error; +} + +SYSCALL_DEFINE2(truncate, const char __user *, path, long, length) +{ + return ksys_truncate(path, length); +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length) +{ + return ksys_truncate(path, length); +} +#endif + +int do_ftruncate(struct file *file, loff_t length, unsigned int flags) +{ + struct dentry *dentry = file->f_path.dentry; + struct inode *inode = dentry->d_inode; + int error; + + if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE)) + return -EINVAL; + + /* + * Cannot ftruncate over 2^31 bytes without large file support, either + * through opening with O_LARGEFILE or by using ftruncate64(). + */ + if (length > MAX_NON_LFS && + !(file->f_flags & O_LARGEFILE) && !(flags & FTRUNCATE_LFS)) + return -EINVAL; + + /* Check IS_APPEND on real upper inode */ + if (IS_APPEND(file_inode(file))) + return -EPERM; + + error = security_file_truncate(file); + if (error) + return error; + + error = fsnotify_truncate_perm(&file->f_path, length); + if (error) + return error; + + scoped_guard(super_write, inode->i_sb) + return do_truncate(file_mnt_idmap(file), dentry, length, + ATTR_MTIME | ATTR_CTIME, file); +} + +int ksys_ftruncate(unsigned int fd, loff_t length, unsigned int flags) +{ + if (length < 0) + return -EINVAL; + CLASS(fd, f)(fd); + if (fd_empty(f)) + return -EBADF; + + return do_ftruncate(fd_file(f), length, flags); +} + +SYSCALL_DEFINE2(ftruncate, unsigned int, fd, off_t, length) +{ + return ksys_ftruncate(fd, length, 0); +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_off_t, length) +{ + return ksys_ftruncate(fd, length, 0); +} +#endif + +/* LFS versions of truncate are only needed on 32 bit machines */ +#if BITS_PER_LONG == 32 +SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length) +{ + return ksys_truncate(path, length); +} + +SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length) +{ + return ksys_ftruncate(fd, length, FTRUNCATE_LFS); +} +#endif /* BITS_PER_LONG == 32 */ + +#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_TRUNCATE64) +COMPAT_SYSCALL_DEFINE3(truncate64, const char __user *, pathname, + compat_arg_u64_dual(length)) +{ + return ksys_truncate(pathname, compat_arg_u64_glue(length)); +} +#endif + +#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FTRUNCATE64) +COMPAT_SYSCALL_DEFINE3(ftruncate64, unsigned int, fd, + compat_arg_u64_dual(length)) +{ + return ksys_ftruncate(fd, compat_arg_u64_glue(length), FTRUNCATE_LFS); +} +#endif + +int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len) +{ + struct inode *inode = file_inode(file); + int ret; + loff_t sum; + + if (offset < 0 || len <= 0) + return -EINVAL; + + if (mode & ~(FALLOC_FL_MODE_MASK | FALLOC_FL_KEEP_SIZE)) + return -EOPNOTSUPP; + + /* + * Modes are exclusive, even if that is not obvious from the encoding + * as bit masks and the mix with the flag in the same namespace. + * + * To make things even more complicated, FALLOC_FL_ALLOCATE_RANGE is + * encoded as no bit set. + */ + switch (mode & FALLOC_FL_MODE_MASK) { + case FALLOC_FL_ALLOCATE_RANGE: + case FALLOC_FL_UNSHARE_RANGE: + case FALLOC_FL_ZERO_RANGE: + break; + case FALLOC_FL_PUNCH_HOLE: + if (!(mode & FALLOC_FL_KEEP_SIZE)) + return -EOPNOTSUPP; + break; + case FALLOC_FL_COLLAPSE_RANGE: + case FALLOC_FL_INSERT_RANGE: + case FALLOC_FL_WRITE_ZEROES: + if (mode & FALLOC_FL_KEEP_SIZE) + return -EOPNOTSUPP; + break; + default: + return -EOPNOTSUPP; + } + + if (!(file->f_mode & FMODE_WRITE)) + return -EBADF; + + /* + * On append-only files only space preallocation is supported. + */ + if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode)) + return -EPERM; + + if (IS_IMMUTABLE(inode)) + return -EPERM; + + /* + * We cannot allow any fallocate operation on an active swapfile + */ + if (IS_SWAPFILE(inode)) + return -ETXTBSY; + + /* + * Revalidate the write permissions, in case security policy has + * changed since the files were opened. + */ + ret = security_file_permission(file, MAY_WRITE); + if (ret) + return ret; + + ret = fsnotify_file_area_perm(file, MAY_WRITE, &offset, len); + if (ret) + return ret; + + if (S_ISFIFO(inode->i_mode)) + return -ESPIPE; + + if (S_ISDIR(inode->i_mode)) + return -EISDIR; + + if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) + return -ENODEV; + + /* Check for wraparound */ + if (check_add_overflow(offset, len, &sum)) + return -EFBIG; + + if (sum > inode->i_sb->s_maxbytes) + return -EFBIG; + + if (!file->f_op->fallocate) + return -EOPNOTSUPP; + + file_start_write(file); + ret = file->f_op->fallocate(file, mode, offset, len); + + /* + * Create inotify and fanotify events. + * + * To keep the logic simple always create events if fallocate succeeds. + * This implies that events are even created if the file size remains + * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE. + */ + if (ret == 0) + fsnotify_modify(file); + + file_end_write(file); + return ret; +} +EXPORT_SYMBOL_GPL(vfs_fallocate); + +int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len) +{ + CLASS(fd, f)(fd); + + if (fd_empty(f)) + return -EBADF; + + return vfs_fallocate(fd_file(f), mode, offset, len); +} + +SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len) +{ + return ksys_fallocate(fd, mode, offset, len); +} + +#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FALLOCATE) +COMPAT_SYSCALL_DEFINE6(fallocate, int, fd, int, mode, compat_arg_u64_dual(offset), + compat_arg_u64_dual(len)) +{ + return ksys_fallocate(fd, mode, compat_arg_u64_glue(offset), + compat_arg_u64_glue(len)); +} +#endif + +/* + * access() needs to use the real uid/gid, not the effective uid/gid. + * We do this by temporarily clearing all FS-related capabilities and + * switching the fsuid/fsgid around to the real ones. + * + * Creating new credentials is expensive, so we try to skip doing it, + * which we can if the result would match what we already got. + */ +static bool access_need_override_creds(int flags) +{ + const struct cred *cred; + + if (flags & AT_EACCESS) + return false; + + cred = current_cred(); + if (!uid_eq(cred->fsuid, cred->uid) || + !gid_eq(cred->fsgid, cred->gid)) + return true; + + if (!issecure(SECURE_NO_SETUID_FIXUP)) { + kuid_t root_uid = make_kuid(cred->user_ns, 0); + if (!uid_eq(cred->uid, root_uid)) { + if (!cap_isclear(cred->cap_effective)) + return true; + } else { + if (!cap_isidentical(cred->cap_effective, + cred->cap_permitted)) + return true; + } + } + + return false; +} + +static const struct cred *access_override_creds(void) +{ + struct cred *override_cred; + + override_cred = prepare_creds(); + if (!override_cred) + return NULL; + + /* + * XXX access_need_override_creds performs checks in hopes of skipping + * this work. Make sure it stays in sync if making any changes in this + * routine. + */ + + override_cred->fsuid = override_cred->uid; + override_cred->fsgid = override_cred->gid; + + if (!issecure(SECURE_NO_SETUID_FIXUP)) { + /* Clear the capabilities if we switch to a non-root user */ + kuid_t root_uid = make_kuid(override_cred->user_ns, 0); + if (!uid_eq(override_cred->uid, root_uid)) + cap_clear(override_cred->cap_effective); + else + override_cred->cap_effective = + override_cred->cap_permitted; + } + + /* + * The new set of credentials can *only* be used in + * task-synchronous circumstances, and does not need + * RCU freeing, unless somebody then takes a separate + * reference to it. + * + * NOTE! This is _only_ true because this credential + * is used purely for override_creds() that installs + * it as the subjective cred. Other threads will be + * accessing ->real_cred, not the subjective cred. + * + * If somebody _does_ make a copy of this (using the + * 'get_current_cred()' function), that will clear the + * non_rcu field, because now that other user may be + * expecting RCU freeing. But normal thread-synchronous + * cred accesses will keep things non-racy to avoid RCU + * freeing. + */ + override_cred->non_rcu = 1; + return override_creds(override_cred); +} + +static int do_faccessat(int dfd, const char __user *filename, int mode, int flags) +{ + struct path path; + struct inode *inode; + int res; + unsigned int lookup_flags = LOOKUP_FOLLOW; + const struct cred *old_cred = NULL; + + if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */ + return -EINVAL; + + if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) + return -EINVAL; + + if (flags & AT_SYMLINK_NOFOLLOW) + lookup_flags &= ~LOOKUP_FOLLOW; + + if (access_need_override_creds(flags)) { + old_cred = access_override_creds(); + if (!old_cred) + return -ENOMEM; + } + + CLASS(filename_uflags, name)(filename, flags); +retry: + res = filename_lookup(dfd, name, lookup_flags, &path, NULL); + if (res) + goto out; + + inode = d_backing_inode(path.dentry); + + if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) { + /* + * MAY_EXEC on regular files is denied if the fs is mounted + * with the "noexec" flag. + */ + res = -EACCES; + if (path_noexec(&path)) + goto out_path_release; + } + + res = inode_permission(mnt_idmap(path.mnt), inode, mode | MAY_ACCESS); + /* SuS v2 requires we report a read only fs too */ + if (res || !(mode & S_IWOTH) || special_file(inode->i_mode)) + goto out_path_release; + /* + * This is a rare case where using __mnt_is_readonly() + * is OK without a mnt_want/drop_write() pair. Since + * no actual write to the fs is performed here, we do + * not need to telegraph to that to anyone. + * + * By doing this, we accept that this access is + * inherently racy and know that the fs may change + * state before we even see this result. + */ + if (__mnt_is_readonly(path.mnt)) + res = -EROFS; + +out_path_release: + path_put(&path); + if (retry_estale(res, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } +out: + if (old_cred) + put_cred(revert_creds(old_cred)); + + return res; +} + +SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode) +{ + return do_faccessat(dfd, filename, mode, 0); +} + +SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode, + int, flags) +{ + return do_faccessat(dfd, filename, mode, flags); +} + +SYSCALL_DEFINE2(access, const char __user *, filename, int, mode) +{ + return do_faccessat(AT_FDCWD, filename, mode, 0); +} + +SYSCALL_DEFINE1(chdir, const char __user *, filename) +{ + struct path path; + int error; + unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY; + CLASS(filename, name)(filename); +retry: + error = filename_lookup(AT_FDCWD, name, lookup_flags, &path, NULL); + if (!error) { + error = path_permission(&path, MAY_EXEC | MAY_CHDIR); + if (!error) + set_fs_pwd(current->fs, &path); + path_put(&path); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } + } + return error; +} + +SYSCALL_DEFINE1(fchdir, unsigned int, fd) +{ + int error; + + if ((int)fd == FD_FAILFS_ROOT) + return failfs_current_chdir(); + + CLASS(fd_raw, f)(fd); + if (fd_empty(f)) + return -EBADF; + + if (!d_can_lookup(fd_file(f)->f_path.dentry)) + return -ENOTDIR; + + error = file_permission(fd_file(f), MAY_EXEC | MAY_CHDIR); + if (!error) + set_fs_pwd(current->fs, &fd_file(f)->f_path); + return error; +} + +SYSCALL_DEFINE1(chroot, const char __user *, filename) +{ + struct path path; + int error; + unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY; + CLASS(filename, name)(filename); +retry: + error = filename_lookup(AT_FDCWD, name, lookup_flags, &path, NULL); + if (error) + return error; + + error = path_permission(&path, MAY_EXEC | MAY_CHDIR); + if (error) + goto dput_and_out; + + error = -EPERM; + if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT)) + goto dput_and_out; + error = security_path_chroot(&path); + if (!error) + set_fs_root(current->fs, &path); +dput_and_out: + path_put(&path); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } + return error; +} + +SYSCALL_DEFINE2(fchroot, int, fd, unsigned int, flags) +{ + struct path path; + int error; + + if (flags) + return -EINVAL; + + if (fd == FD_FAILFS_ROOT) { + if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT)) { + if (!task_no_new_privs(current)) + return -EPERM; + /* A shared fs_struct lets a sibling exec setuid past the check above. */ + if (current->fs->users != 1) + return -EINVAL; + /* Moving the root to failfs lifts the old root's ".." barrier. */ + if (current_chrooted()) + return -EPERM; + } + failfs_get_root(&path); + } else { + CLASS(fd_raw, f)(fd); + if (fd_empty(f)) + return -EBADF; + + if (!d_can_lookup(fd_file(f)->f_path.dentry)) + return -ENOTDIR; + + error = file_permission(fd_file(f), MAY_EXEC | MAY_CHDIR); + if (error) + return error; + + if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT)) + return -EPERM; + + path = fd_file(f)->f_path; + path_get(&path); + } + + error = security_path_chroot(&path); + if (!error) + set_fs_root(current->fs, &path); + path_put(&path); + return error; +} + +int chmod_common(const struct path *path, umode_t mode) +{ + struct inode *inode = path->dentry->d_inode; + struct delegated_inode delegated_inode = { }; + struct iattr newattrs; + int error; + + error = mnt_want_write(path->mnt); + if (error) + return error; +retry_deleg: + error = inode_lock_killable(inode); + if (error) + goto out_mnt_unlock; + error = security_path_chmod(path, mode); + if (error) + goto out_unlock; + newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); + newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; + error = notify_change(mnt_idmap(path->mnt), path->dentry, + &newattrs, &delegated_inode); +out_unlock: + inode_unlock(inode); + if (is_delegated(&delegated_inode)) { + error = break_deleg_wait(&delegated_inode); + if (!error) + goto retry_deleg; + } +out_mnt_unlock: + mnt_drop_write(path->mnt); + return error; +} + +int vfs_fchmod(struct file *file, umode_t mode) +{ + audit_file(file); + return chmod_common(&file->f_path, mode); +} + +SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode) +{ + CLASS(fd, f)(fd); + + if (fd_empty(f)) + return -EBADF; + + return vfs_fchmod(fd_file(f), mode); +} + +static int do_fchmodat(int dfd, const char __user *filename, umode_t mode, + unsigned int flags) +{ + struct path path; + int error; + unsigned int lookup_flags; + + if (unlikely(flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))) + return -EINVAL; + + lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW; + CLASS(filename_uflags, name)(filename, flags); +retry: + error = filename_lookup(dfd, name, lookup_flags, &path, NULL); + if (!error) { + error = chmod_common(&path, mode); + path_put(&path); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } + } + return error; +} + +SYSCALL_DEFINE4(fchmodat2, int, dfd, const char __user *, filename, + umode_t, mode, unsigned int, flags) +{ + return do_fchmodat(dfd, filename, mode, flags); +} + +SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, + umode_t, mode) +{ + return do_fchmodat(dfd, filename, mode, 0); +} + +SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode) +{ + return do_fchmodat(AT_FDCWD, filename, mode, 0); +} + +/* + * Check whether @kuid is valid and if so generate and set vfsuid_t in + * ia_vfsuid. + * + * Return: true if @kuid is valid, false if not. + */ +static inline bool setattr_vfsuid(struct iattr *attr, kuid_t kuid) +{ + if (!uid_valid(kuid)) + return false; + attr->ia_valid |= ATTR_UID; + attr->ia_vfsuid = VFSUIDT_INIT(kuid); + return true; +} + +/* + * Check whether @kgid is valid and if so generate and set vfsgid_t in + * ia_vfsgid. + * + * Return: true if @kgid is valid, false if not. + */ +static inline bool setattr_vfsgid(struct iattr *attr, kgid_t kgid) +{ + if (!gid_valid(kgid)) + return false; + attr->ia_valid |= ATTR_GID; + attr->ia_vfsgid = VFSGIDT_INIT(kgid); + return true; +} + +int chown_common(const struct path *path, uid_t user, gid_t group) +{ + struct mnt_idmap *idmap; + struct user_namespace *fs_userns; + struct inode *inode = path->dentry->d_inode; + struct delegated_inode delegated_inode = { }; + int error; + struct iattr newattrs; + kuid_t uid; + kgid_t gid; + + uid = make_kuid(current_user_ns(), user); + gid = make_kgid(current_user_ns(), group); + + idmap = mnt_idmap(path->mnt); + fs_userns = i_user_ns(inode); + +retry_deleg: + newattrs.ia_vfsuid = INVALID_VFSUID; + newattrs.ia_vfsgid = INVALID_VFSGID; + newattrs.ia_valid = ATTR_CTIME; + if ((user != (uid_t)-1) && !setattr_vfsuid(&newattrs, uid)) + return -EINVAL; + if ((group != (gid_t)-1) && !setattr_vfsgid(&newattrs, gid)) + return -EINVAL; + error = inode_lock_killable(inode); + if (error) + return error; + if (!S_ISDIR(inode->i_mode)) + newattrs.ia_valid |= ATTR_KILL_SUID | ATTR_KILL_PRIV | + setattr_should_drop_sgid(idmap, inode); + /* Continue to send actual fs values, not the mount values. */ + error = security_path_chown( + path, + from_vfsuid(idmap, fs_userns, newattrs.ia_vfsuid), + from_vfsgid(idmap, fs_userns, newattrs.ia_vfsgid)); + if (!error) + error = notify_change(idmap, path->dentry, &newattrs, + &delegated_inode); + inode_unlock(inode); + if (is_delegated(&delegated_inode)) { + error = break_deleg_wait(&delegated_inode); + if (!error) + goto retry_deleg; + } + return error; +} + +int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group, + int flag) +{ + struct path path; + int error; + int lookup_flags; + + if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0) + return -EINVAL; + + lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW; + CLASS(filename_uflags, name)(filename, flag); +retry: + error = filename_lookup(dfd, name, lookup_flags, &path, NULL); + if (!error) { + error = mnt_want_write(path.mnt); + if (!error) { + error = chown_common(&path, user, group); + mnt_drop_write(path.mnt); + } + path_put(&path); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } + } + return error; +} + +SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user, + gid_t, group, int, flag) +{ + return do_fchownat(dfd, filename, user, group, flag); +} + +SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group) +{ + return do_fchownat(AT_FDCWD, filename, user, group, 0); +} + +SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group) +{ + return do_fchownat(AT_FDCWD, filename, user, group, + AT_SYMLINK_NOFOLLOW); +} + +int vfs_fchown(struct file *file, uid_t user, gid_t group) +{ + int error; + + error = mnt_want_write_file(file); + if (error) + return error; + audit_file(file); + error = chown_common(&file->f_path, user, group); + mnt_drop_write_file(file); + return error; +} + +int ksys_fchown(unsigned int fd, uid_t user, gid_t group) +{ + CLASS(fd, f)(fd); + + if (fd_empty(f)) + return -EBADF; + + return vfs_fchown(fd_file(f), user, group); +} + +SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group) +{ + return ksys_fchown(fd, user, group); +} + +static inline int file_get_write_access(struct file *f) +{ + int error; + + error = get_write_access(f->f_inode); + if (unlikely(error)) + return error; + error = mnt_get_write_access(f->f_path.mnt); + if (unlikely(error)) + goto cleanup_inode; + if (unlikely(f->f_mode & FMODE_BACKING)) { + error = mnt_get_write_access(backing_file_user_path(f)->mnt); + if (unlikely(error)) + goto cleanup_mnt; + } + return 0; + +cleanup_mnt: + mnt_put_write_access(f->f_path.mnt); +cleanup_inode: + put_write_access(f->f_inode); + return error; +} + +static int do_dentry_open(struct file *f, + int (*open)(struct inode *, struct file *)) +{ + static const struct file_operations empty_fops = {}; + struct inode *inode = f->f_path.dentry->d_inode; + int error; + + path_get(&f->f_path); + f->f_inode = inode; + f->f_mapping = inode->i_mapping; + f->f_wb_err = filemap_sample_wb_err(f->f_mapping); + f->f_sb_err = file_sample_sb_err(f); + + if (unlikely(f->f_flags & O_PATH)) { + f->f_mode = FMODE_PATH | FMODE_OPENED; + file_set_fsnotify_mode(f, FMODE_NONOTIFY); + f->f_op = &empty_fops; + return 0; + } + + if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) { + i_readcount_inc(inode); + } else if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) { + error = file_get_write_access(f); + if (unlikely(error)) + goto cleanup_file; + f->f_mode |= FMODE_WRITER; + } + + /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */ + if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)) + f->f_mode |= FMODE_ATOMIC_POS; + + f->f_op = fops_get(inode->i_fop); + if (WARN_ON(!f->f_op)) { + error = -ENODEV; + goto cleanup_all; + } + + error = security_file_open(f); + if (unlikely(error)) + goto cleanup_all; + + /* + * Call fsnotify open permission hook and set FMODE_NONOTIFY_* bits + * according to existing permission watches. + * If FMODE_NONOTIFY mode was already set for an fanotify fd or for a + * pseudo file, this call will not change the mode. + */ + error = fsnotify_open_perm_and_set_mode(f); + if (unlikely(error)) + goto cleanup_all; + + error = break_lease(file_inode(f), f->f_flags); + if (unlikely(error)) + goto cleanup_all; + + /* normally all 3 are set; ->open() can clear them if needed */ + f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE; + if (!open) + open = f->f_op->open; + if (open) { + error = open(inode, f); + if (error) + goto cleanup_all; + } + f->f_mode |= FMODE_OPENED; + if ((f->f_mode & FMODE_READ) && + likely(f->f_op->read || f->f_op->read_iter)) + f->f_mode |= FMODE_CAN_READ; + if ((f->f_mode & FMODE_WRITE) && + likely(f->f_op->write || f->f_op->write_iter)) + f->f_mode |= FMODE_CAN_WRITE; + if ((f->f_mode & FMODE_LSEEK) && !f->f_op->llseek) + f->f_mode &= ~FMODE_LSEEK; + if (f->f_mapping->a_ops && f->f_mapping->a_ops->direct_IO) + f->f_mode |= FMODE_CAN_ODIRECT; + + f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC | __O_REGULAR); + f->f_iocb_flags = iocb_flags(f); + + file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping); + + if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT)) + return -EINVAL; + + return 0; + +cleanup_all: + if (WARN_ON_ONCE(error > 0)) + error = -EINVAL; + fops_put(f->f_op); + put_file_access(f); +cleanup_file: + path_put(&f->f_path); + f->__f_path.mnt = NULL; + f->__f_path.dentry = NULL; + f->f_inode = NULL; + return error; +} + +/** + * finish_open - finish opening a file + * @file: file pointer + * @dentry: pointer to dentry + * @open: open callback + * + * This can be used to finish opening a file passed to i_op->atomic_open(). + * + * If the open callback is set to NULL, then the standard f_op->open() + * filesystem callback is substituted. + * + * NB: the dentry reference is _not_ consumed. If, for example, the dentry is + * the return value of d_splice_alias(), then the caller needs to perform dput() + * on it after finish_open(). + * + * Returns zero on success or -errno if the open failed. + */ +int finish_open(struct file *file, struct dentry *dentry, + int (*open)(struct inode *, struct file *)) +{ + BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */ + + file->__f_path.dentry = dentry; + return do_dentry_open(file, open); +} +EXPORT_SYMBOL(finish_open); + +/** + * finish_no_open - finish ->atomic_open() without opening the file + * + * @file: file pointer + * @dentry: dentry, ERR_PTR(-E...) or NULL (as returned from ->lookup()) + * + * This can be used to set the result of a lookup in ->atomic_open(). + * + * NB: unlike finish_open() this function does consume the dentry reference and + * the caller need not dput() it. + * + * Returns 0 or -E..., which must be the return value of ->atomic_open() after + * having called this function. + */ +int finish_no_open(struct file *file, struct dentry *dentry) +{ + if (IS_ERR(dentry)) + return PTR_ERR(dentry); + file->__f_path.dentry = dentry; + return 0; +} +EXPORT_SYMBOL(finish_no_open); + +char *file_path(struct file *filp, char *buf, int buflen) +{ + return d_path(&filp->f_path, buf, buflen); +} +EXPORT_SYMBOL(file_path); + +/** + * vfs_open - open the file at the given path + * @path: path to open + * @file: newly allocated file with f_flag initialized + */ +int vfs_open(const struct path *path, struct file *file) +{ + int ret; + + file->__f_path = *path; + ret = do_dentry_open(file, NULL); + if (!ret) { + /* + * Once we return a file with FMODE_OPENED, __fput() will call + * fsnotify_close(), so we need fsnotify_open() here for + * symmetry. + */ + fsnotify_open(file); + } + return ret; +} + +struct file *dentry_open(const struct path *path, int flags, + const struct cred *cred) +{ + int error; + struct file *f; + + /* We must always pass in a valid mount pointer. */ + BUG_ON(!path->mnt); + + f = alloc_empty_file(flags, cred); + if (!IS_ERR(f)) { + error = vfs_open(path, f); + if (error) { + fput(f); + f = ERR_PTR(error); + } + } + return f; +} +EXPORT_SYMBOL(dentry_open); + +struct file *dentry_open_nonotify(const struct path *path, int flags, + const struct cred *cred) +{ + struct file *f = alloc_empty_file(flags, cred); + if (!IS_ERR(f)) { + int error; + + file_set_fsnotify_mode(f, FMODE_NONOTIFY); + error = vfs_open(path, f); + if (error) { + fput(f); + f = ERR_PTR(error); + } + } + return f; +} + +/** + * kernel_file_open - open a file for kernel internal use + * @path: path of the file to open + * @flags: open flags + * @cred: credentials for open + * + * Open a file for use by in-kernel consumers. The file is not accounted + * against nr_files and must not be installed into the file descriptor + * table. + * + * Return: Opened file on success, an error pointer on failure. + */ +struct file *kernel_file_open(const struct path *path, int flags, + const struct cred *cred) +{ + struct file *f; + int error; + + f = alloc_empty_file_noaccount(flags, cred); + if (IS_ERR(f)) + return f; + + error = vfs_open(path, f); + if (error) { + fput(f); + return ERR_PTR(error); + } + return f; +} +EXPORT_SYMBOL_GPL(kernel_file_open); + +#define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE)) +#define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC | O_EMPTYPATH) + +inline struct open_how build_open_how(int flags, umode_t mode) +{ + struct open_how how = { + .flags = flags & VALID_OPEN_FLAGS, + .mode = mode & S_IALLUGO, + }; + + /* O_PATH beats everything else. */ + if (how.flags & O_PATH) + how.flags &= O_PATH_FLAGS; + /* Modes should only be set for create-like flags. */ + if (!WILL_CREATE(how.flags)) + how.mode = 0; + return how; +} + +inline int build_open_flags(const struct open_how *how, struct open_flags *op) +{ + u64 flags = how->flags; + u64 strip = O_CLOEXEC; + int lookup_flags = 0; + int acc_mode = ACC_MODE(flags); + + BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS), + "VALID_OPEN_FLAGS must fit in 32 bits"); + /* The whole point: OPENAT2_REGULAR must be unrepresentable in int. */ + BUILD_BUG_ON_MSG(!upper_32_bits(OPENAT2_REGULAR), + "OPENAT2_REGULAR must live in the upper 32 bits of open_how::flags"); + /* Prevent a future bit collision between UAPI and internal carrier. */ + BUILD_BUG_ON_MSG(OPENAT2_REGULAR & VALID_OPEN_FLAGS, + "OPENAT2_REGULAR must not alias any open()/openat() flag"); + BUILD_BUG_ON_MSG(__O_REGULAR & VALID_OPENAT2_FLAGS, + "__O_REGULAR must not alias any user-visible flag"); + + /* + * Strip flags that aren't relevant in determining struct open_flags. + */ + flags &= ~strip; + + /* + * Older syscalls implicitly clear all of the invalid flags or argument + * values before calling build_open_flags(), but openat2(2) checks all + * of its arguments. + */ + if (flags & ~VALID_OPENAT2_FLAGS) + return -EINVAL; + if (how->resolve & ~VALID_RESOLVE_FLAGS) + return -EINVAL; + + /* Scoping flags are mutually exclusive. */ + if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT)) + return -EINVAL; + + /* Deal with the mode. */ + if (WILL_CREATE(flags)) { + if (how->mode & ~S_IALLUGO) + return -EINVAL; + op->mode = how->mode | S_IFREG; + } else { + if (how->mode != 0) + return -EINVAL; + op->mode = 0; + } + + /* + * Block bugs where O_DIRECTORY | O_CREAT created regular files. + * Note, that blocking O_DIRECTORY | O_CREAT here also protects + * O_TMPFILE below which requires O_DIRECTORY being raised. + */ + if ((flags & (O_DIRECTORY | O_CREAT)) == (O_DIRECTORY | O_CREAT)) + return -EINVAL; + + /* Now handle the creative implementation of O_TMPFILE. */ + if (flags & __O_TMPFILE) { + /* + * In order to ensure programs get explicit errors when trying + * to use O_TMPFILE on old kernels we enforce that O_DIRECTORY + * is raised alongside __O_TMPFILE. + */ + if (!(flags & O_DIRECTORY)) + return -EINVAL; + if (!(acc_mode & MAY_WRITE)) + return -EINVAL; + } + /* + * Asking to open a directory and a regular file at the same time is + * contradictory. + */ + if ((flags & (O_DIRECTORY | OPENAT2_REGULAR)) == + (O_DIRECTORY | OPENAT2_REGULAR)) + return -EINVAL; + + if (flags & O_PATH) { + /* O_PATH only permits certain other flags to be set. */ + if (flags & ~O_PATH_FLAGS) + return -EINVAL; + acc_mode = 0; + } + + /* + * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only + * check for O_DSYNC if the need any syncing at all we enforce it's + * always set instead of having to deal with possibly weird behaviour + * for malicious applications setting only __O_SYNC. + */ + if (flags & __O_SYNC) + flags |= O_DSYNC; + + /* + * Translate the upper-32-bit UAPI bit OPENAT2_REGULAR into the + * kernel-internal lower-32-bit __O_REGULAR carrier so the bit + * survives the assignment to op->open_flag (an int) below and the + * subsequent flow through f->f_flags (unsigned int) and the + * i_op->atomic_open() callback (unsigned). do_dentry_open() strips + * __O_REGULAR before the file becomes visible to userspace. + */ + if (flags & OPENAT2_REGULAR) { + flags &= ~OPENAT2_REGULAR; + flags |= __O_REGULAR; + } + + op->open_flag = flags; + + /* O_TRUNC implies we need access checks for write permissions */ + if (flags & O_TRUNC) + acc_mode |= MAY_WRITE; + + /* Allow the LSM permission hook to distinguish append + access from general write access. */ + if (flags & O_APPEND) + acc_mode |= MAY_APPEND; + + op->acc_mode = acc_mode; + + op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN; + + if (flags & O_CREAT) { + op->intent |= LOOKUP_CREATE; + if (flags & O_EXCL) { + op->intent |= LOOKUP_EXCL; + flags |= O_NOFOLLOW; + } + } + + if (flags & O_DIRECTORY) + lookup_flags |= LOOKUP_DIRECTORY; + if (!(flags & O_NOFOLLOW)) + lookup_flags |= LOOKUP_FOLLOW; + if (flags & O_EMPTYPATH) + lookup_flags |= LOOKUP_EMPTY; + + if (how->resolve & RESOLVE_NO_XDEV) + lookup_flags |= LOOKUP_NO_XDEV; + if (how->resolve & RESOLVE_NO_MAGICLINKS) + lookup_flags |= LOOKUP_NO_MAGICLINKS; + if (how->resolve & RESOLVE_NO_SYMLINKS) + lookup_flags |= LOOKUP_NO_SYMLINKS; + if (how->resolve & RESOLVE_BENEATH) + lookup_flags |= LOOKUP_BENEATH; + if (how->resolve & RESOLVE_IN_ROOT) + lookup_flags |= LOOKUP_IN_ROOT; + if (how->resolve & RESOLVE_CACHED) { + /* Don't bother even trying for create/truncate/tmpfile open */ + if (flags & (O_TRUNC | O_CREAT | __O_TMPFILE)) + return -EAGAIN; + lookup_flags |= LOOKUP_CACHED; + } + + op->lookup_flags = lookup_flags; + return 0; +} + +/** + * file_open_name - open file and return file pointer + * + * @name: struct filename containing path to open + * @flags: open flags as per the open(2) second argument + * @mode: mode for the new file if O_CREAT is set, else ignored + * + * This is the helper to open a file from kernelspace if you really + * have to. But in generally you should not do this, so please move + * along, nothing to see here.. + */ +struct file *file_open_name(struct filename *name, int flags, umode_t mode) +{ + struct open_flags op; + struct open_how how = build_open_how(flags, mode); + int err = build_open_flags(&how, &op); + if (err) + return ERR_PTR(err); + return do_file_open(AT_FDCWD, name, &op); +} + +/** + * filp_open - open file and return file pointer + * + * @filename: path to open + * @flags: open flags as per the open(2) second argument + * @mode: mode for the new file if O_CREAT is set, else ignored + * + * This is the helper to open a file from kernelspace if you really + * have to. But in generally you should not do this, so please move + * along, nothing to see here.. + */ +struct file *filp_open(const char *filename, int flags, umode_t mode) +{ + CLASS(filename_kernel, name)(filename); + return file_open_name(name, flags, mode); +} +EXPORT_SYMBOL(filp_open); + +struct file *file_open_root(const struct path *root, + const char *filename, int flags, umode_t mode) +{ + struct open_flags op; + struct open_how how = build_open_how(flags, mode); + int err = build_open_flags(&how, &op); + if (err) + return ERR_PTR(err); + return do_file_open_root(root, filename, &op); +} +EXPORT_SYMBOL(file_open_root); + +static int do_sys_openat2(int dfd, const char __user *filename, + struct open_how *how) +{ + struct open_flags op; + int err = build_open_flags(how, &op); + if (unlikely(err)) + return err; + + CLASS(filename_flags, name)(filename, op.lookup_flags); + return FD_ADD(how->flags, do_file_open(dfd, name, &op)); +} + +int do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode) +{ + struct open_how how = build_open_how(flags, mode); + return do_sys_openat2(dfd, filename, &how); +} + + +SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode) +{ + if (force_o_largefile()) + flags |= O_LARGEFILE; + return do_sys_open(AT_FDCWD, filename, flags, mode); +} + +SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, + umode_t, mode) +{ + if (force_o_largefile()) + flags |= O_LARGEFILE; + return do_sys_open(dfd, filename, flags, mode); +} + +SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename, + struct open_how __user *, how, size_t, usize) +{ + int err; + struct open_how tmp; + + BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0); + BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST); + + if (unlikely(usize < OPEN_HOW_SIZE_VER0)) + return -EINVAL; + if (unlikely(usize > PAGE_SIZE)) + return -E2BIG; + + err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize); + if (err) + return err; + + audit_openat2_how(&tmp); + + /* O_LARGEFILE is only allowed for non-O_PATH. */ + if (!(tmp.flags & O_PATH) && force_o_largefile()) + tmp.flags |= O_LARGEFILE; + + return do_sys_openat2(dfd, filename, &tmp); +} + +#ifdef CONFIG_COMPAT +/* + * Exactly like sys_open(), except that it doesn't set the + * O_LARGEFILE flag. + */ +COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode) +{ + return do_sys_open(AT_FDCWD, filename, flags, mode); +} + +/* + * Exactly like sys_openat(), except that it doesn't set the + * O_LARGEFILE flag. + */ +COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode) +{ + return do_sys_open(dfd, filename, flags, mode); +} +#endif + +#ifndef __alpha__ + +/* + * For backward compatibility? Maybe this should be moved + * into arch/i386 instead? + */ +SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode) +{ + int flags = O_CREAT | O_WRONLY | O_TRUNC; + + if (force_o_largefile()) + flags |= O_LARGEFILE; + return do_sys_open(AT_FDCWD, pathname, flags, mode); +} +#endif + +/* + * "id" is the POSIX thread ID. We use the + * files pointer for this.. + */ +static int filp_flush(struct file *filp, fl_owner_t id) +{ + int retval = 0; + + if (CHECK_DATA_CORRUPTION(file_count(filp) == 0, filp, + "VFS: Close: file count is 0 (f_op=%ps)", + filp->f_op)) { + return 0; + } + + if (filp->f_op->flush) + retval = filp->f_op->flush(filp, id); + + if (likely(!(filp->f_mode & FMODE_PATH))) { + dnotify_flush(filp, id); + locks_remove_posix(filp, id); + } + return retval; +} + +int filp_close(struct file *filp, fl_owner_t id) +{ + int retval; + + retval = filp_flush(filp, id); + fput_close(filp); + + return retval; +} +EXPORT_SYMBOL(filp_close); + +/* + * Careful here! We test whether the file pointer is NULL before + * releasing the fd. This ensures that one clone task can't release + * an fd while another clone is opening it. + */ +SYSCALL_DEFINE1(close, unsigned int, fd) +{ + int retval; + struct file *file; + + file = file_close_fd(fd); + if (!file) + return -EBADF; + + retval = filp_flush(file, current->files); + + /* + * We're returning to user space. Don't bother + * with any delayed fput() cases. + */ + fput_close_sync(file); + + if (likely(retval == 0)) + return 0; + + /* can't restart close syscall because file table entry was cleared */ + if (retval == -ERESTARTSYS || + retval == -ERESTARTNOINTR || + retval == -ERESTARTNOHAND || + retval == -ERESTART_RESTARTBLOCK) + retval = -EINTR; + + return retval; +} + +/* + * This routine simulates a hangup on the tty, to arrange that users + * are given clean terminals at login time. + */ +SYSCALL_DEFINE0(vhangup) +{ + if (capable(CAP_SYS_TTY_CONFIG)) { + tty_vhangup_self(); + return 0; + } + return -EPERM; +} + +/* + * Called when an inode is about to be open. + * We use this to disallow opening large files on 32bit systems if + * the caller didn't specify O_LARGEFILE. On 64bit systems we force + * on this flag in sys_open. + */ +int generic_file_open(struct inode * inode, struct file * filp) +{ + if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS) + return -EOVERFLOW; + return 0; +} + +EXPORT_SYMBOL(generic_file_open); + +/* + * This is used by subsystems that don't want seekable + * file descriptors. The function is not supposed to ever fail, the only + * reason it returns an 'int' and not 'void' is so that it can be plugged + * directly into file_operations structure. + */ +int nonseekable_open(struct inode *inode, struct file *filp) +{ + filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE); + return 0; +} + +EXPORT_SYMBOL(nonseekable_open); + +/* + * stream_open is used by subsystems that want stream-like file descriptors. + * Such file descriptors are not seekable and don't have notion of position + * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL). + * Contrary to file descriptors of other regular files, .read() and .write() + * can run simultaneously. + * + * stream_open never fails and is marked to return int so that it could be + * directly used as file_operations.open . + */ +int stream_open(struct inode *inode, struct file *filp) +{ + filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS); + filp->f_mode |= FMODE_STREAM; + return 0; +} + +EXPORT_SYMBOL(stream_open); -- cgit v1.3.1