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fs: split receive_fd_replace from __receive_fd

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receive_fd_replace shares almost no code with the general case, so split
it out.  Also remove the "Bump the sock usage counts" comment from
both copies, as that is now what __receive_sock actually does.

[AV: ... and make the only user of receive_fd_replace() choose between
it and receive_fd() according to what userland had passed to it in
flags]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Christoph Hellwig 2021-03-25 09:22:09 +01:00 committed by Al Viro
parent a38fd87484
commit 42eb0d54c0
3 changed files with 35 additions and 32 deletions
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39
fs/file.c
View File

@ -1068,8 +1068,6 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags)
/** /**
* __receive_fd() - Install received file into file descriptor table * __receive_fd() - Install received file into file descriptor table
*
* @fd: fd to install into (if negative, a new fd will be allocated)
* @file: struct file that was received from another process * @file: struct file that was received from another process
* @ufd: __user pointer to write new fd number to * @ufd: __user pointer to write new fd number to
* @o_flags: the O_* flags to apply to the new fd entry * @o_flags: the O_* flags to apply to the new fd entry
@ -1083,7 +1081,7 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags)
* *
* Returns newly install fd or -ve on error. * Returns newly install fd or -ve on error.
*/ */
int __receive_fd(int fd, struct file *file, int __user *ufd, unsigned int o_flags) int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags)
{ {
int new_fd; int new_fd;
int error; int error;
@ -1092,32 +1090,33 @@ int __receive_fd(int fd, struct file *file, int __user *ufd, unsigned int o_flag
if (error) if (error)
return error; return error;
if (fd < 0) { new_fd = get_unused_fd_flags(o_flags);
new_fd = get_unused_fd_flags(o_flags); if (new_fd < 0)
if (new_fd < 0) return new_fd;
return new_fd;
} else {
new_fd = fd;
}
if (ufd) { if (ufd) {
error = put_user(new_fd, ufd); error = put_user(new_fd, ufd);
if (error) { if (error) {
if (fd < 0) put_unused_fd(new_fd);
put_unused_fd(new_fd);
return error; return error;
} }
} }
if (fd < 0) { fd_install(new_fd, get_file(file));
fd_install(new_fd, get_file(file)); __receive_sock(file);
} else { return new_fd;
error = replace_fd(new_fd, file, o_flags); }
if (error)
return error;
}
/* Bump the sock usage counts, if any. */ int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags)
{
int error;
error = security_file_receive(file);
if (error)
return error;
error = replace_fd(new_fd, file, o_flags);
if (error)
return error;
__receive_sock(file); __receive_sock(file);
return new_fd; return new_fd;
} }

11
include/linux/file.h
View File

@ -92,23 +92,20 @@ extern void put_unused_fd(unsigned int fd);
extern void fd_install(unsigned int fd, struct file *file); extern void fd_install(unsigned int fd, struct file *file);
extern int __receive_fd(int fd, struct file *file, int __user *ufd, extern int __receive_fd(struct file *file, int __user *ufd,
unsigned int o_flags); unsigned int o_flags);
static inline int receive_fd_user(struct file *file, int __user *ufd, static inline int receive_fd_user(struct file *file, int __user *ufd,
unsigned int o_flags) unsigned int o_flags)
{ {
if (ufd == NULL) if (ufd == NULL)
return -EFAULT; return -EFAULT;
return __receive_fd(-1, file, ufd, o_flags); return __receive_fd(file, ufd, o_flags);
} }
static inline int receive_fd(struct file *file, unsigned int o_flags) static inline int receive_fd(struct file *file, unsigned int o_flags)
{ {
return __receive_fd(-1, file, NULL, o_flags); return __receive_fd(file, NULL, o_flags);
}
static inline int receive_fd_replace(int fd, struct file *file, unsigned int o_flags)
{
return __receive_fd(fd, file, NULL, o_flags);
} }
int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags);
extern void flush_delayed_fput(void); extern void flush_delayed_fput(void);
extern void __fput_sync(struct file *); extern void __fput_sync(struct file *);

17
kernel/seccomp.c
View File

@ -119,8 +119,11 @@ struct seccomp_kaddfd {
int fd; int fd;
unsigned int flags; unsigned int flags;
/* To only be set on reply */ union {
int ret; bool setfd;
/* To only be set on reply */
int ret;
};
struct completion completion; struct completion completion;
struct list_head list; struct list_head list;
}; };
@ -1069,7 +1072,11 @@ static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd)
* that it has been handled. * that it has been handled.
*/ */
list_del_init(&addfd->list); list_del_init(&addfd->list);
addfd->ret = receive_fd_replace(addfd->fd, addfd->file, addfd->flags); if (!addfd->setfd)
addfd->ret = receive_fd(addfd->file, addfd->flags);
else
addfd->ret = receive_fd_replace(addfd->fd, addfd->file,
addfd->flags);
complete(&addfd->completion); complete(&addfd->completion);
} }
@ -1583,8 +1590,8 @@ static long seccomp_notify_addfd(struct seccomp_filter *filter,
return -EBADF; return -EBADF;
kaddfd.flags = addfd.newfd_flags; kaddfd.flags = addfd.newfd_flags;
kaddfd.fd = (addfd.flags & SECCOMP_ADDFD_FLAG_SETFD) ? kaddfd.setfd = addfd.flags & SECCOMP_ADDFD_FLAG_SETFD;
addfd.newfd : -1; kaddfd.fd = addfd.newfd;
init_completion(&kaddfd.completion); init_completion(&kaddfd.completion);
ret = mutex_lock_interruptible(&filter->notify_lock); ret = mutex_lock_interruptible(&filter->notify_lock);