diff options
Diffstat (limited to 'kernel/fs/fcntl.c')
| -rw-r--r-- | kernel/fs/fcntl.c | 759 |
1 files changed, 759 insertions, 0 deletions
diff --git a/kernel/fs/fcntl.c b/kernel/fs/fcntl.c new file mode 100644 index 000000000..ee85cd4e1 --- /dev/null +++ b/kernel/fs/fcntl.c @@ -0,0 +1,759 @@ +/* + * linux/fs/fcntl.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +#include <linux/syscalls.h> +#include <linux/init.h> +#include <linux/mm.h> +#include <linux/fs.h> +#include <linux/file.h> +#include <linux/fdtable.h> +#include <linux/capability.h> +#include <linux/dnotify.h> +#include <linux/slab.h> +#include <linux/module.h> +#include <linux/pipe_fs_i.h> +#include <linux/security.h> +#include <linux/ptrace.h> +#include <linux/signal.h> +#include <linux/rcupdate.h> +#include <linux/pid_namespace.h> +#include <linux/user_namespace.h> +#include <linux/shmem_fs.h> + +#include <asm/poll.h> +#include <asm/siginfo.h> +#include <asm/uaccess.h> + +#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME) + +static int setfl(int fd, struct file * filp, unsigned long arg) +{ + struct inode * inode = file_inode(filp); + int error = 0; + + /* + * O_APPEND cannot be cleared if the file is marked as append-only + * and the file is open for write. + */ + if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode)) + return -EPERM; + + /* O_NOATIME can only be set by the owner or superuser */ + if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME)) + if (!inode_owner_or_capable(inode)) + return -EPERM; + + /* required for strict SunOS emulation */ + if (O_NONBLOCK != O_NDELAY) + if (arg & O_NDELAY) + arg |= O_NONBLOCK; + + if (arg & O_DIRECT) { + if (!filp->f_mapping || !filp->f_mapping->a_ops || + !filp->f_mapping->a_ops->direct_IO) + return -EINVAL; + } + + if (filp->f_op->check_flags) + error = filp->f_op->check_flags(arg); + if (error) + return error; + + /* + * ->fasync() is responsible for setting the FASYNC bit. + */ + if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) { + error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0); + if (error < 0) + goto out; + if (error > 0) + error = 0; + } + spin_lock(&filp->f_lock); + filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); + spin_unlock(&filp->f_lock); + + out: + return error; +} + +static void f_modown(struct file *filp, struct pid *pid, enum pid_type type, + int force) +{ + write_lock_irq(&filp->f_owner.lock); + if (force || !filp->f_owner.pid) { + put_pid(filp->f_owner.pid); + filp->f_owner.pid = get_pid(pid); + filp->f_owner.pid_type = type; + + if (pid) { + const struct cred *cred = current_cred(); + filp->f_owner.uid = cred->uid; + filp->f_owner.euid = cred->euid; + } + } + write_unlock_irq(&filp->f_owner.lock); +} + +void __f_setown(struct file *filp, struct pid *pid, enum pid_type type, + int force) +{ + security_file_set_fowner(filp); + f_modown(filp, pid, type, force); +} +EXPORT_SYMBOL(__f_setown); + +void f_setown(struct file *filp, unsigned long arg, int force) +{ + enum pid_type type; + struct pid *pid; + int who = arg; + type = PIDTYPE_PID; + if (who < 0) { + type = PIDTYPE_PGID; + who = -who; + } + rcu_read_lock(); + pid = find_vpid(who); + __f_setown(filp, pid, type, force); + rcu_read_unlock(); +} +EXPORT_SYMBOL(f_setown); + +void f_delown(struct file *filp) +{ + f_modown(filp, NULL, PIDTYPE_PID, 1); +} + +pid_t f_getown(struct file *filp) +{ + pid_t pid; + read_lock(&filp->f_owner.lock); + pid = pid_vnr(filp->f_owner.pid); + if (filp->f_owner.pid_type == PIDTYPE_PGID) + pid = -pid; + read_unlock(&filp->f_owner.lock); + return pid; +} + +static int f_setown_ex(struct file *filp, unsigned long arg) +{ + struct f_owner_ex __user *owner_p = (void __user *)arg; + struct f_owner_ex owner; + struct pid *pid; + int type; + int ret; + + ret = copy_from_user(&owner, owner_p, sizeof(owner)); + if (ret) + return -EFAULT; + + switch (owner.type) { + case F_OWNER_TID: + type = PIDTYPE_MAX; + break; + + case F_OWNER_PID: + type = PIDTYPE_PID; + break; + + case F_OWNER_PGRP: + type = PIDTYPE_PGID; + break; + + default: + return -EINVAL; + } + + rcu_read_lock(); + pid = find_vpid(owner.pid); + if (owner.pid && !pid) + ret = -ESRCH; + else + __f_setown(filp, pid, type, 1); + rcu_read_unlock(); + + return ret; +} + +static int f_getown_ex(struct file *filp, unsigned long arg) +{ + struct f_owner_ex __user *owner_p = (void __user *)arg; + struct f_owner_ex owner; + int ret = 0; + + read_lock(&filp->f_owner.lock); + owner.pid = pid_vnr(filp->f_owner.pid); + switch (filp->f_owner.pid_type) { + case PIDTYPE_MAX: + owner.type = F_OWNER_TID; + break; + + case PIDTYPE_PID: + owner.type = F_OWNER_PID; + break; + + case PIDTYPE_PGID: + owner.type = F_OWNER_PGRP; + break; + + default: + WARN_ON(1); + ret = -EINVAL; + break; + } + read_unlock(&filp->f_owner.lock); + + if (!ret) { + ret = copy_to_user(owner_p, &owner, sizeof(owner)); + if (ret) + ret = -EFAULT; + } + return ret; +} + +#ifdef CONFIG_CHECKPOINT_RESTORE +static int f_getowner_uids(struct file *filp, unsigned long arg) +{ + struct user_namespace *user_ns = current_user_ns(); + uid_t __user *dst = (void __user *)arg; + uid_t src[2]; + int err; + + read_lock(&filp->f_owner.lock); + src[0] = from_kuid(user_ns, filp->f_owner.uid); + src[1] = from_kuid(user_ns, filp->f_owner.euid); + read_unlock(&filp->f_owner.lock); + + err = put_user(src[0], &dst[0]); + err |= put_user(src[1], &dst[1]); + + return err; +} +#else +static int f_getowner_uids(struct file *filp, unsigned long arg) +{ + return -EINVAL; +} +#endif + +static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, + struct file *filp) +{ + long err = -EINVAL; + + switch (cmd) { + case F_DUPFD: + err = f_dupfd(arg, filp, 0); + break; + case F_DUPFD_CLOEXEC: + err = f_dupfd(arg, filp, O_CLOEXEC); + break; + case F_GETFD: + err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; + break; + case F_SETFD: + err = 0; + set_close_on_exec(fd, arg & FD_CLOEXEC); + break; + case F_GETFL: + err = filp->f_flags; + break; + case F_SETFL: + err = setfl(fd, filp, arg); + break; +#if BITS_PER_LONG != 32 + /* 32-bit arches must use fcntl64() */ + case F_OFD_GETLK: +#endif + case F_GETLK: + err = fcntl_getlk(filp, cmd, (struct flock __user *) arg); + break; +#if BITS_PER_LONG != 32 + /* 32-bit arches must use fcntl64() */ + case F_OFD_SETLK: + case F_OFD_SETLKW: +#endif + /* Fallthrough */ + case F_SETLK: + case F_SETLKW: + err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg); + break; + case F_GETOWN: + /* + * XXX If f_owner is a process group, the + * negative return value will get converted + * into an error. Oops. If we keep the + * current syscall conventions, the only way + * to fix this will be in libc. + */ + err = f_getown(filp); + force_successful_syscall_return(); + break; + case F_SETOWN: + f_setown(filp, arg, 1); + err = 0; + break; + case F_GETOWN_EX: + err = f_getown_ex(filp, arg); + break; + case F_SETOWN_EX: + err = f_setown_ex(filp, arg); + break; + case F_GETOWNER_UIDS: + err = f_getowner_uids(filp, arg); + break; + case F_GETSIG: + err = filp->f_owner.signum; + break; + case F_SETSIG: + /* arg == 0 restores default behaviour. */ + if (!valid_signal(arg)) { + break; + } + err = 0; + filp->f_owner.signum = arg; + break; + case F_GETLEASE: + err = fcntl_getlease(filp); + break; + case F_SETLEASE: + err = fcntl_setlease(fd, filp, arg); + break; + case F_NOTIFY: + err = fcntl_dirnotify(fd, filp, arg); + break; + case F_SETPIPE_SZ: + case F_GETPIPE_SZ: + err = pipe_fcntl(filp, cmd, arg); + break; + case F_ADD_SEALS: + case F_GET_SEALS: + err = shmem_fcntl(filp, cmd, arg); + break; + default: + break; + } + return err; +} + +static int check_fcntl_cmd(unsigned cmd) +{ + switch (cmd) { + case F_DUPFD: + case F_DUPFD_CLOEXEC: + case F_GETFD: + case F_SETFD: + case F_GETFL: + return 1; + } + return 0; +} + +SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg) +{ + struct fd f = fdget_raw(fd); + long err = -EBADF; + + if (!f.file) + goto out; + + if (unlikely(f.file->f_mode & FMODE_PATH)) { + if (!check_fcntl_cmd(cmd)) + goto out1; + } + + err = security_file_fcntl(f.file, cmd, arg); + if (!err) + err = do_fcntl(fd, cmd, arg, f.file); + +out1: + fdput(f); +out: + return err; +} + +#if BITS_PER_LONG == 32 +SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, + unsigned long, arg) +{ + struct fd f = fdget_raw(fd); + long err = -EBADF; + + if (!f.file) + goto out; + + if (unlikely(f.file->f_mode & FMODE_PATH)) { + if (!check_fcntl_cmd(cmd)) + goto out1; + } + + err = security_file_fcntl(f.file, cmd, arg); + if (err) + goto out1; + + switch (cmd) { + case F_GETLK64: + case F_OFD_GETLK: + err = fcntl_getlk64(f.file, cmd, (struct flock64 __user *) arg); + break; + case F_SETLK64: + case F_SETLKW64: + case F_OFD_SETLK: + case F_OFD_SETLKW: + err = fcntl_setlk64(fd, f.file, cmd, + (struct flock64 __user *) arg); + break; + default: + err = do_fcntl(fd, cmd, arg, f.file); + break; + } +out1: + fdput(f); +out: + return err; +} +#endif + +/* Table to convert sigio signal codes into poll band bitmaps */ + +static const long band_table[NSIGPOLL] = { + POLLIN | POLLRDNORM, /* POLL_IN */ + POLLOUT | POLLWRNORM | POLLWRBAND, /* POLL_OUT */ + POLLIN | POLLRDNORM | POLLMSG, /* POLL_MSG */ + POLLERR, /* POLL_ERR */ + POLLPRI | POLLRDBAND, /* POLL_PRI */ + POLLHUP | POLLERR /* POLL_HUP */ +}; + +static inline int sigio_perm(struct task_struct *p, + struct fown_struct *fown, int sig) +{ + const struct cred *cred; + int ret; + + rcu_read_lock(); + cred = __task_cred(p); + ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) || + uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) || + uid_eq(fown->uid, cred->suid) || uid_eq(fown->uid, cred->uid)) && + !security_file_send_sigiotask(p, fown, sig)); + rcu_read_unlock(); + return ret; +} + +static void send_sigio_to_task(struct task_struct *p, + struct fown_struct *fown, + int fd, int reason, int group) +{ + /* + * F_SETSIG can change ->signum lockless in parallel, make + * sure we read it once and use the same value throughout. + */ + int signum = ACCESS_ONCE(fown->signum); + + if (!sigio_perm(p, fown, signum)) + return; + + switch (signum) { + siginfo_t si; + default: + /* Queue a rt signal with the appropriate fd as its + value. We use SI_SIGIO as the source, not + SI_KERNEL, since kernel signals always get + delivered even if we can't queue. Failure to + queue in this case _should_ be reported; we fall + back to SIGIO in that case. --sct */ + si.si_signo = signum; + si.si_errno = 0; + si.si_code = reason; + /* Make sure we are called with one of the POLL_* + reasons, otherwise we could leak kernel stack into + userspace. */ + BUG_ON((reason & __SI_MASK) != __SI_POLL); + if (reason - POLL_IN >= NSIGPOLL) + si.si_band = ~0L; + else + si.si_band = band_table[reason - POLL_IN]; + si.si_fd = fd; + if (!do_send_sig_info(signum, &si, p, group)) + break; + /* fall-through: fall back on the old plain SIGIO signal */ + case 0: + do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, group); + } +} + +void send_sigio(struct fown_struct *fown, int fd, int band) +{ + struct task_struct *p; + enum pid_type type; + struct pid *pid; + int group = 1; + + read_lock(&fown->lock); + + type = fown->pid_type; + if (type == PIDTYPE_MAX) { + group = 0; + type = PIDTYPE_PID; + } + + pid = fown->pid; + if (!pid) + goto out_unlock_fown; + + read_lock(&tasklist_lock); + do_each_pid_task(pid, type, p) { + send_sigio_to_task(p, fown, fd, band, group); + } while_each_pid_task(pid, type, p); + read_unlock(&tasklist_lock); + out_unlock_fown: + read_unlock(&fown->lock); +} + +static void send_sigurg_to_task(struct task_struct *p, + struct fown_struct *fown, int group) +{ + if (sigio_perm(p, fown, SIGURG)) + do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, group); +} + +int send_sigurg(struct fown_struct *fown) +{ + struct task_struct *p; + enum pid_type type; + struct pid *pid; + int group = 1; + int ret = 0; + + read_lock(&fown->lock); + + type = fown->pid_type; + if (type == PIDTYPE_MAX) { + group = 0; + type = PIDTYPE_PID; + } + + pid = fown->pid; + if (!pid) + goto out_unlock_fown; + + ret = 1; + + read_lock(&tasklist_lock); + do_each_pid_task(pid, type, p) { + send_sigurg_to_task(p, fown, group); + } while_each_pid_task(pid, type, p); + read_unlock(&tasklist_lock); + out_unlock_fown: + read_unlock(&fown->lock); + return ret; +} + +static DEFINE_SPINLOCK(fasync_lock); +static struct kmem_cache *fasync_cache __read_mostly; + +static void fasync_free_rcu(struct rcu_head *head) +{ + kmem_cache_free(fasync_cache, + container_of(head, struct fasync_struct, fa_rcu)); +} + +/* + * Remove a fasync entry. If successfully removed, return + * positive and clear the FASYNC flag. If no entry exists, + * do nothing and return 0. + * + * NOTE! It is very important that the FASYNC flag always + * match the state "is the filp on a fasync list". + * + */ +int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) +{ + struct fasync_struct *fa, **fp; + int result = 0; + + spin_lock(&filp->f_lock); + spin_lock(&fasync_lock); + for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { + if (fa->fa_file != filp) + continue; + + spin_lock_irq(&fa->fa_lock); + fa->fa_file = NULL; + spin_unlock_irq(&fa->fa_lock); + + *fp = fa->fa_next; + call_rcu(&fa->fa_rcu, fasync_free_rcu); + filp->f_flags &= ~FASYNC; + result = 1; + break; + } + spin_unlock(&fasync_lock); + spin_unlock(&filp->f_lock); + return result; +} + +struct fasync_struct *fasync_alloc(void) +{ + return kmem_cache_alloc(fasync_cache, GFP_KERNEL); +} + +/* + * NOTE! This can be used only for unused fasync entries: + * entries that actually got inserted on the fasync list + * need to be released by rcu - see fasync_remove_entry. + */ +void fasync_free(struct fasync_struct *new) +{ + kmem_cache_free(fasync_cache, new); +} + +/* + * Insert a new entry into the fasync list. Return the pointer to the + * old one if we didn't use the new one. + * + * NOTE! It is very important that the FASYNC flag always + * match the state "is the filp on a fasync list". + */ +struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new) +{ + struct fasync_struct *fa, **fp; + + spin_lock(&filp->f_lock); + spin_lock(&fasync_lock); + for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { + if (fa->fa_file != filp) + continue; + + spin_lock_irq(&fa->fa_lock); + fa->fa_fd = fd; + spin_unlock_irq(&fa->fa_lock); + goto out; + } + + spin_lock_init(&new->fa_lock); + new->magic = FASYNC_MAGIC; + new->fa_file = filp; + new->fa_fd = fd; + new->fa_next = *fapp; + rcu_assign_pointer(*fapp, new); + filp->f_flags |= FASYNC; + +out: + spin_unlock(&fasync_lock); + spin_unlock(&filp->f_lock); + return fa; +} + +/* + * Add a fasync entry. Return negative on error, positive if + * added, and zero if did nothing but change an existing one. + */ +static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp) +{ + struct fasync_struct *new; + + new = fasync_alloc(); + if (!new) + return -ENOMEM; + + /* + * fasync_insert_entry() returns the old (update) entry if + * it existed. + * + * So free the (unused) new entry and return 0 to let the + * caller know that we didn't add any new fasync entries. + */ + if (fasync_insert_entry(fd, filp, fapp, new)) { + fasync_free(new); + return 0; + } + + return 1; +} + +/* + * fasync_helper() is used by almost all character device drivers + * to set up the fasync queue, and for regular files by the file + * lease code. It returns negative on error, 0 if it did no changes + * and positive if it added/deleted the entry. + */ +int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) +{ + if (!on) + return fasync_remove_entry(filp, fapp); + return fasync_add_entry(fd, filp, fapp); +} + +EXPORT_SYMBOL(fasync_helper); + +/* + * rcu_read_lock() is held + */ +static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band) +{ + while (fa) { + struct fown_struct *fown; + unsigned long flags; + + if (fa->magic != FASYNC_MAGIC) { + printk(KERN_ERR "kill_fasync: bad magic number in " + "fasync_struct!\n"); + return; + } + spin_lock_irqsave(&fa->fa_lock, flags); + if (fa->fa_file) { + fown = &fa->fa_file->f_owner; + /* Don't send SIGURG to processes which have not set a + queued signum: SIGURG has its own default signalling + mechanism. */ + if (!(sig == SIGURG && fown->signum == 0)) + send_sigio(fown, fa->fa_fd, band); + } + spin_unlock_irqrestore(&fa->fa_lock, flags); + fa = rcu_dereference(fa->fa_next); + } +} + +void kill_fasync(struct fasync_struct **fp, int sig, int band) +{ + /* First a quick test without locking: usually + * the list is empty. + */ + if (*fp) { + rcu_read_lock(); + kill_fasync_rcu(rcu_dereference(*fp), sig, band); + rcu_read_unlock(); + } +} +EXPORT_SYMBOL(kill_fasync); + +static int __init fcntl_init(void) +{ + /* + * Please add new bits here to ensure allocation uniqueness. + * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY + * is defined as O_NONBLOCK on some platforms and not on others. + */ + BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32( + O_RDONLY | O_WRONLY | O_RDWR | + O_CREAT | O_EXCL | O_NOCTTY | + O_TRUNC | O_APPEND | /* O_NONBLOCK | */ + __O_SYNC | O_DSYNC | FASYNC | + O_DIRECT | O_LARGEFILE | O_DIRECTORY | + O_NOFOLLOW | O_NOATIME | O_CLOEXEC | + __FMODE_EXEC | O_PATH | __O_TMPFILE | + __FMODE_NONOTIFY + )); + + fasync_cache = kmem_cache_create("fasync_cache", + sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL); + return 0; +} + +module_init(fcntl_init) |