diff options
Diffstat (limited to 'fs/open.c')
| -rw-r--r-- | fs/open.c | 147 |
1 files changed, 113 insertions, 34 deletions
diff --git a/fs/open.c b/fs/open.c index b62f5c0923a8..8cdb2b675867 100644 --- a/fs/open.c +++ b/fs/open.c @@ -955,48 +955,84 @@ struct file *open_with_fake_path(const struct path *path, int flags, } EXPORT_SYMBOL(open_with_fake_path); -static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op) +#define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE)) +#define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC) + +static 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; +} + +static inline int build_open_flags(const struct open_how *how, + struct open_flags *op) { + int flags = how->flags; int lookup_flags = 0; int acc_mode = ACC_MODE(flags); + /* Must never be set by userspace */ + flags &= ~(FMODE_NONOTIFY | O_CLOEXEC); + /* - * Clear out all open flags we don't know about so that we don't report - * them in fcntl(F_GETFD) or similar interfaces. + * 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. */ - flags &= VALID_OPEN_FLAGS; + if (flags & ~VALID_OPEN_FLAGS) + return -EINVAL; + if (how->resolve & ~VALID_RESOLVE_FLAGS) + return -EINVAL; - if (flags & (O_CREAT | __O_TMPFILE)) - op->mode = (mode & S_IALLUGO) | S_IFREG; - else + /* 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; - - /* Must never be set by userspace */ - flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC; + } /* - * 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. + * In order to ensure programs get explicit errors when trying to use + * O_TMPFILE on old kernels, O_TMPFILE is implemented such that it + * looks like (O_DIRECTORY|O_RDWR & ~O_CREAT) to old kernels. But we + * have to require userspace to explicitly set it. */ - if (flags & __O_SYNC) - flags |= O_DSYNC; - if (flags & __O_TMPFILE) { if ((flags & O_TMPFILE_MASK) != O_TMPFILE) return -EINVAL; if (!(acc_mode & MAY_WRITE)) return -EINVAL; - } else if (flags & O_PATH) { - /* - * If we have O_PATH in the open flag. Then we - * cannot have anything other than the below set of flags - */ - flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH; + } + 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; + op->open_flag = flags; /* O_TRUNC implies we need access checks for write permissions */ @@ -1022,6 +1058,18 @@ static inline int build_open_flags(int flags, umode_t mode, struct open_flags *o lookup_flags |= LOOKUP_DIRECTORY; if (!(flags & O_NOFOLLOW)) lookup_flags |= LOOKUP_FOLLOW; + + 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; + op->lookup_flags = lookup_flags; return 0; } @@ -1040,8 +1088,11 @@ static inline int build_open_flags(int flags, umode_t mode, struct open_flags *o struct file *file_open_name(struct filename *name, int flags, umode_t mode) { struct open_flags op; - int err = build_open_flags(flags, mode, &op); - return err ? ERR_PTR(err) : do_filp_open(AT_FDCWD, name, &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_filp_open(AT_FDCWD, name, &op); } /** @@ -1072,17 +1123,19 @@ struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt, const char *filename, int flags, umode_t mode) { struct open_flags op; - int err = build_open_flags(flags, mode, &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(dentry, mnt, filename, &op); } EXPORT_SYMBOL(file_open_root); -long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode) +static long do_sys_openat2(int dfd, const char __user *filename, + struct open_how *how) { struct open_flags op; - int fd = build_open_flags(flags, mode, &op); + int fd = build_open_flags(how, &op); struct filename *tmp; if (fd) @@ -1092,7 +1145,7 @@ long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode) if (IS_ERR(tmp)) return PTR_ERR(tmp); - fd = get_unused_fd_flags(flags); + fd = get_unused_fd_flags(how->flags); if (fd >= 0) { struct file *f = do_filp_open(dfd, tmp, &op); if (IS_ERR(f)) { @@ -1107,12 +1160,16 @@ long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode) return fd; } -SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode) +long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode) { - if (force_o_largefile()) - flags |= O_LARGEFILE; + struct open_how how = build_open_how(flags, mode); + return do_sys_openat2(dfd, filename, &how); +} - return do_sys_open(AT_FDCWD, filename, flags, mode); + +SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode) +{ + return ksys_open(filename, flags, mode); } SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, @@ -1120,10 +1177,32 @@ SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, { 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; + + err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize); + if (err) + return err; + + /* 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 |