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fs/fcntl.c
16.7 KB
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/* * 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> |
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#include <linux/fdtable.h> |
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#include <linux/capability.h> |
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#include <linux/dnotify.h> |
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#include <linux/slab.h> #include <linux/module.h> |
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#include <linux/pipe_fs_i.h> |
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#include <linux/security.h> #include <linux/ptrace.h> |
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#include <linux/signal.h> |
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#include <linux/rcupdate.h> |
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#include <linux/pid_namespace.h> |
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#include <linux/user_namespace.h> |
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#include <linux/shmem_fs.h> |
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#include <asm/poll.h> #include <asm/siginfo.h> #include <asm/uaccess.h> |
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#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME) |
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static int setfl(int fd, struct file * filp, unsigned long arg) { |
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struct inode * inode = file_inode(filp); |
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int error = 0; |
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/* * 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)) |
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return -EPERM; /* O_NOATIME can only be set by the owner or superuser */ if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME)) |
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if (!inode_owner_or_capable(inode)) |
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return -EPERM; /* required for strict SunOS emulation */ if (O_NONBLOCK != O_NDELAY) if (arg & O_NDELAY) arg |= O_NONBLOCK; |
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/* Pipe packetized mode is controlled by O_DIRECT flag */ if (!S_ISFIFO(filp->f_inode->i_mode) && (arg & O_DIRECT)) { |
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if (!filp->f_mapping || !filp->f_mapping->a_ops || !filp->f_mapping->a_ops->direct_IO) return -EINVAL; } |
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if (filp->f_op->check_flags) |
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error = filp->f_op->check_flags(arg); if (error) return error; |
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/* |
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* ->fasync() is responsible for setting the FASYNC bit. |
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*/ |
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if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) { |
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error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0); if (error < 0) goto out; |
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if (error > 0) error = 0; |
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} |
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spin_lock(&filp->f_lock); |
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filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); |
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spin_unlock(&filp->f_lock); |
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|
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out: |
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return error; } |
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static void f_modown(struct file *filp, struct pid *pid, enum pid_type type, |
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int force) |
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{ |
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write_lock_irq(&filp->f_owner.lock); |
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if (force || !filp->f_owner.pid) { |
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put_pid(filp->f_owner.pid); filp->f_owner.pid = get_pid(pid); filp->f_owner.pid_type = type; |
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if (pid) { const struct cred *cred = current_cred(); filp->f_owner.uid = cred->uid; filp->f_owner.euid = cred->euid; } |
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} |
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write_unlock_irq(&filp->f_owner.lock); |
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} |
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void __f_setown(struct file *filp, struct pid *pid, enum pid_type type, |
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int force) |
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{ |
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security_file_set_fowner(filp); |
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f_modown(filp, pid, type, force); |
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} |
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EXPORT_SYMBOL(__f_setown); |
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|
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void f_setown(struct file *filp, unsigned long arg, int force) |
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{ enum pid_type type; struct pid *pid; int who = arg; |
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type = PIDTYPE_PID; if (who < 0) { type = PIDTYPE_PGID; who = -who; } rcu_read_lock(); |
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pid = find_vpid(who); |
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__f_setown(filp, pid, type, force); |
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rcu_read_unlock(); |
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} |
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EXPORT_SYMBOL(f_setown); void f_delown(struct file *filp) { |
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f_modown(filp, NULL, PIDTYPE_PID, 1); |
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} pid_t f_getown(struct file *filp) { pid_t pid; |
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read_lock(&filp->f_owner.lock); |
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pid = pid_vnr(filp->f_owner.pid); |
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if (filp->f_owner.pid_type == PIDTYPE_PGID) pid = -pid; |
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read_unlock(&filp->f_owner.lock); |
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return pid; |
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} |
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static int f_setown_ex(struct file *filp, unsigned long arg) { |
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struct f_owner_ex __user *owner_p = (void __user *)arg; |
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struct f_owner_ex owner; struct pid *pid; int type; int ret; ret = copy_from_user(&owner, owner_p, sizeof(owner)); if (ret) |
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return -EFAULT; |
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switch (owner.type) { case F_OWNER_TID: type = PIDTYPE_MAX; break; case F_OWNER_PID: type = PIDTYPE_PID; break; |
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case F_OWNER_PGRP: |
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type = PIDTYPE_PGID; break; default: return -EINVAL; } rcu_read_lock(); pid = find_vpid(owner.pid); if (owner.pid && !pid) ret = -ESRCH; else |
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__f_setown(filp, pid, type, 1); |
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rcu_read_unlock(); return ret; } static int f_getown_ex(struct file *filp, unsigned long arg) { |
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struct f_owner_ex __user *owner_p = (void __user *)arg; |
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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: |
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owner.type = F_OWNER_PGRP; |
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break; default: WARN_ON(1); ret = -EINVAL; break; } read_unlock(&filp->f_owner.lock); |
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if (!ret) { |
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ret = copy_to_user(owner_p, &owner, sizeof(owner)); |
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if (ret) ret = -EFAULT; } |
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return ret; } |
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#ifdef CONFIG_CHECKPOINT_RESTORE static int f_getowner_uids(struct file *filp, unsigned long arg) { struct user_namespace *user_ns = current_user_ns(); |
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uid_t __user *dst = (void __user *)arg; |
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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 |
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static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, struct file *filp) { long err = -EINVAL; switch (cmd) { case F_DUPFD: |
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err = f_dupfd(arg, filp, 0); break; |
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case F_DUPFD_CLOEXEC: |
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err = f_dupfd(arg, filp, O_CLOEXEC); |
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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; |
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#if BITS_PER_LONG != 32 /* 32-bit arches must use fcntl64() */ |
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case F_OFD_GETLK: |
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#endif |
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case F_GETLK: |
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err = fcntl_getlk(filp, cmd, (struct flock __user *) arg); |
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break; |
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#if BITS_PER_LONG != 32 /* 32-bit arches must use fcntl64() */ |
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case F_OFD_SETLK: case F_OFD_SETLKW: |
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#endif /* Fallthrough */ |
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case F_SETLK: case F_SETLKW: |
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err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg); |
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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. */ |
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err = f_getown(filp); |
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force_successful_syscall_return(); break; case F_SETOWN: |
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f_setown(filp, arg, 1); err = 0; |
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break; |
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case F_GETOWN_EX: err = f_getown_ex(filp, arg); break; case F_SETOWN_EX: err = f_setown_ex(filp, arg); break; |
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case F_GETOWNER_UIDS: err = f_getowner_uids(filp, arg); break; |
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case F_GETSIG: err = filp->f_owner.signum; break; case F_SETSIG: /* arg == 0 restores default behaviour. */ |
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if (!valid_signal(arg)) { |
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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; |
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case F_SETPIPE_SZ: case F_GETPIPE_SZ: err = pipe_fcntl(filp, cmd, arg); break; |
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case F_ADD_SEALS: case F_GET_SEALS: err = shmem_fcntl(filp, cmd, arg); break; |
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default: break; } return err; } |
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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; } |
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SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg) |
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{ |
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struct fd f = fdget_raw(fd); |
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long err = -EBADF; |
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if (!f.file) |
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goto out; |
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if (unlikely(f.file->f_mode & FMODE_PATH)) { |
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if (!check_fcntl_cmd(cmd)) goto out1; |
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} |
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err = security_file_fcntl(f.file, cmd, arg); |
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if (!err) |
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err = do_fcntl(fd, cmd, arg, f.file); |
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out1: |
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fdput(f); |
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out: return err; } #if BITS_PER_LONG == 32 |
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SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, unsigned long, arg) |
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{ |
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struct fd f = fdget_raw(fd); |
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long err = -EBADF; |
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|
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if (!f.file) |
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goto out; |
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if (unlikely(f.file->f_mode & FMODE_PATH)) { |
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if (!check_fcntl_cmd(cmd)) goto out1; |
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} |
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err = security_file_fcntl(f.file, cmd, arg); |
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if (err) goto out1; |
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switch (cmd) { |
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case F_GETLK64: |
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case F_OFD_GETLK: |
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err = fcntl_getlk64(f.file, cmd, (struct flock64 __user *) arg); break; case F_SETLK64: case F_SETLKW64: |
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case F_OFD_SETLK: case F_OFD_SETLKW: |
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err = fcntl_setlk64(fd, f.file, cmd, (struct flock64 __user *) arg); break; default: err = do_fcntl(fd, cmd, arg, f.file); break; |
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} |
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out1: |
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fdput(f); |
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out: return err; } #endif /* Table to convert sigio signal codes into poll band bitmaps */ |
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static const long band_table[NSIGPOLL] = { |
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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) { |
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const struct cred *cred; int ret; rcu_read_lock(); cred = __task_cred(p); |
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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)) && |
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!security_file_send_sigiotask(p, fown, sig)); rcu_read_unlock(); return ret; |
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} static void send_sigio_to_task(struct task_struct *p, |
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struct fown_struct *fown, |
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int fd, int reason, int group) |
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{ |
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/* * 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)) |
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return; |
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switch (signum) { |
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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 */ |
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si.si_signo = signum; |
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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. */ |
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BUG_ON((reason & __SI_MASK) != __SI_POLL); |
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if (reason - POLL_IN >= NSIGPOLL) si.si_band = ~0L; else si.si_band = band_table[reason - POLL_IN]; si.si_fd = fd; |
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if (!do_send_sig_info(signum, &si, p, group)) |
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break; /* fall-through: fall back on the old plain SIGIO signal */ case 0: |
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do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, group); |
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} } void send_sigio(struct fown_struct *fown, int fd, int band) { struct task_struct *p; |
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enum pid_type type; struct pid *pid; |
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int group = 1; |
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read_lock(&fown->lock); |
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|
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type = fown->pid_type; |
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if (type == PIDTYPE_MAX) { group = 0; type = PIDTYPE_PID; } |
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pid = fown->pid; if (!pid) goto out_unlock_fown; read_lock(&tasklist_lock); |
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do_each_pid_task(pid, type, p) { |
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send_sigio_to_task(p, fown, fd, band, group); |
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} while_each_pid_task(pid, type, p); |
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read_unlock(&tasklist_lock); out_unlock_fown: read_unlock(&fown->lock); } static void send_sigurg_to_task(struct task_struct *p, |
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struct fown_struct *fown, int group) |
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{ if (sigio_perm(p, fown, SIGURG)) |
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do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, group); |
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} int send_sigurg(struct fown_struct *fown) { struct task_struct *p; |
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enum pid_type type; struct pid *pid; |
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int group = 1; |
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int ret = 0; |
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read_lock(&fown->lock); |
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|
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type = fown->pid_type; |
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if (type == PIDTYPE_MAX) { group = 0; type = PIDTYPE_PID; } |
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pid = fown->pid; if (!pid) goto out_unlock_fown; ret = 1; read_lock(&tasklist_lock); |
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do_each_pid_task(pid, type, p) { |
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527 |
send_sigurg_to_task(p, fown, group); |
609d7fa95
|
528 |
} while_each_pid_task(pid, type, p); |
1da177e4c
|
529 530 531 532 533 |
read_unlock(&tasklist_lock); out_unlock_fown: read_unlock(&fown->lock); return ret; } |
989a29792
|
534 |
static DEFINE_SPINLOCK(fasync_lock); |
e18b890bb
|
535 |
static struct kmem_cache *fasync_cache __read_mostly; |
1da177e4c
|
536 |
|
989a29792
|
537 538 539 540 541 |
static void fasync_free_rcu(struct rcu_head *head) { kmem_cache_free(fasync_cache, container_of(head, struct fasync_struct, fa_rcu)); } |
1da177e4c
|
542 |
/* |
53281b6d3
|
543 544 545 546 547 548 549 |
* 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". * |
1da177e4c
|
550 |
*/ |
f7347ce4e
|
551 |
int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) |
1da177e4c
|
552 553 |
{ struct fasync_struct *fa, **fp; |
1da177e4c
|
554 |
int result = 0; |
53281b6d3
|
555 |
spin_lock(&filp->f_lock); |
989a29792
|
556 |
spin_lock(&fasync_lock); |
53281b6d3
|
557 558 559 |
for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { if (fa->fa_file != filp) continue; |
989a29792
|
560 561 562 563 |
spin_lock_irq(&fa->fa_lock); fa->fa_file = NULL; spin_unlock_irq(&fa->fa_lock); |
53281b6d3
|
564 |
*fp = fa->fa_next; |
989a29792
|
565 |
call_rcu(&fa->fa_rcu, fasync_free_rcu); |
53281b6d3
|
566 567 568 |
filp->f_flags &= ~FASYNC; result = 1; break; |
1da177e4c
|
569 |
} |
989a29792
|
570 |
spin_unlock(&fasync_lock); |
53281b6d3
|
571 572 573 |
spin_unlock(&filp->f_lock); return result; } |
f7347ce4e
|
574 575 576 577 |
struct fasync_struct *fasync_alloc(void) { return kmem_cache_alloc(fasync_cache, GFP_KERNEL); } |
53281b6d3
|
578 |
/* |
f7347ce4e
|
579 580 581 |
* 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. |
53281b6d3
|
582 |
*/ |
f7347ce4e
|
583 |
void fasync_free(struct fasync_struct *new) |
53281b6d3
|
584 |
{ |
f7347ce4e
|
585 586 |
kmem_cache_free(fasync_cache, new); } |
53281b6d3
|
587 |
|
f7347ce4e
|
588 589 590 |
/* * Insert a new entry into the fasync list. Return the pointer to the * old one if we didn't use the new one. |
55f335a88
|
591 592 593 |
* * NOTE! It is very important that the FASYNC flag always * match the state "is the filp on a fasync list". |
f7347ce4e
|
594 595 596 597 |
*/ struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new) { struct fasync_struct *fa, **fp; |
4a6a44996
|
598 |
|
4a6a44996
|
599 |
spin_lock(&filp->f_lock); |
989a29792
|
600 |
spin_lock(&fasync_lock); |
1da177e4c
|
601 |
for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { |
53281b6d3
|
602 603 |
if (fa->fa_file != filp) continue; |
989a29792
|
604 605 |
spin_lock_irq(&fa->fa_lock); |
53281b6d3
|
606 |
fa->fa_fd = fd; |
989a29792
|
607 |
spin_unlock_irq(&fa->fa_lock); |
53281b6d3
|
608 |
goto out; |
1da177e4c
|
609 |
} |
989a29792
|
610 |
spin_lock_init(&new->fa_lock); |
53281b6d3
|
611 612 613 614 |
new->magic = FASYNC_MAGIC; new->fa_file = filp; new->fa_fd = fd; new->fa_next = *fapp; |
989a29792
|
615 |
rcu_assign_pointer(*fapp, new); |
53281b6d3
|
616 |
filp->f_flags |= FASYNC; |
1da177e4c
|
617 |
out: |
989a29792
|
618 |
spin_unlock(&fasync_lock); |
4a6a44996
|
619 |
spin_unlock(&filp->f_lock); |
f7347ce4e
|
620 621 622 623 624 625 |
return fa; } /* * Add a fasync entry. Return negative on error, positive if * added, and zero if did nothing but change an existing one. |
f7347ce4e
|
626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 |
*/ 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; |
1da177e4c
|
648 |
} |
53281b6d3
|
649 650 651 652 653 654 655 656 657 658 659 660 |
/* * 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); } |
1da177e4c
|
661 |
EXPORT_SYMBOL(fasync_helper); |
989a29792
|
662 663 664 665 |
/* * rcu_read_lock() is held */ static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band) |
1da177e4c
|
666 667 |
{ while (fa) { |
989a29792
|
668 |
struct fown_struct *fown; |
f4985dc71
|
669 |
unsigned long flags; |
1da177e4c
|
670 671 672 673 674 675 |
if (fa->magic != FASYNC_MAGIC) { printk(KERN_ERR "kill_fasync: bad magic number in " "fasync_struct! "); return; } |
f4985dc71
|
676 |
spin_lock_irqsave(&fa->fa_lock, flags); |
989a29792
|
677 678 679 680 681 682 683 684 |
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); } |
f4985dc71
|
685 |
spin_unlock_irqrestore(&fa->fa_lock, flags); |
989a29792
|
686 |
fa = rcu_dereference(fa->fa_next); |
1da177e4c
|
687 688 |
} } |
1da177e4c
|
689 690 691 692 693 694 |
void kill_fasync(struct fasync_struct **fp, int sig, int band) { /* First a quick test without locking: usually * the list is empty. */ if (*fp) { |
989a29792
|
695 696 697 |
rcu_read_lock(); kill_fasync_rcu(rcu_dereference(*fp), sig, band); rcu_read_unlock(); |
1da177e4c
|
698 699 700 |
} } EXPORT_SYMBOL(kill_fasync); |
454eedb89
|
701 |
static int __init fcntl_init(void) |
1da177e4c
|
702 |
{ |
3ab04d5cf
|
703 704 705 706 707 |
/* * 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. */ |
75069f2b5
|
708 |
BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32( |
454eedb89
|
709 710 |
O_RDONLY | O_WRONLY | O_RDWR | O_CREAT | O_EXCL | O_NOCTTY | |
3ab04d5cf
|
711 |
O_TRUNC | O_APPEND | /* O_NONBLOCK | */ |
454eedb89
|
712 713 714 |
__O_SYNC | O_DSYNC | FASYNC | O_DIRECT | O_LARGEFILE | O_DIRECTORY | O_NOFOLLOW | O_NOATIME | O_CLOEXEC | |
75069f2b5
|
715 716 |
__FMODE_EXEC | O_PATH | __O_TMPFILE | __FMODE_NONOTIFY |
454eedb89
|
717 |
)); |
1da177e4c
|
718 |
fasync_cache = kmem_cache_create("fasync_cache", |
20c2df83d
|
719 |
sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL); |
1da177e4c
|
720 721 |
return 0; } |
454eedb89
|
722 |
module_init(fcntl_init) |