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Make pipes in CloudABI work.

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Summary:
Pipes in CloudABI are unidirectional. The reason for this is that
CloudABI attempts to provide a uniform runtime environment across
different flavours of UNIX.

Instead of implementing a custom pipe that is unidirectional, we can
simply reuse Capsicum permission bits to support this. This is nice,
because CloudABI already attempts to restrict permission bits to
correspond with the operations that apply to a certain file descriptor.

Replace kern_pipe() and kern_pipe2() by a single kern_pipe() that takes
a pair of filecaps. These filecaps are passed to the newly introduced
falloc_caps() function that creates the descriptors with rights in
place.

Test Plan:
CloudABI pipes seem to be created with proper rights in place:

https://github.com/NuxiNL/cloudlibc/blob/master/src/libc/unistd/pipe_test.c#L44

Reviewers: jilles, mjg

Reviewed By: mjg

Subscribers: imp

Differential Revision: https://reviews.freebsd.org/D3236
This commit is contained in:
ed 2015-07-29 17:18:27 +00:00
parent 4072f1cf76
commit 2aaddce9ba
4 changed files with 27 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
sys/compat/cloudabi/cloudabi_fd.c
View File

@ -120,10 +120,24 @@ int
cloudabi_sys_fd_create2(struct thread *td,
struct cloudabi_sys_fd_create2_args *uap)
{
struct filecaps fcaps1 = {}, fcaps2 = {};
int fds[2];
int error;
switch (uap->type) {
case CLOUDABI_FILETYPE_FIFO:
/*
* CloudABI pipes are unidirectional. Restrict rights on
* the pipe to simulate this.
*/
cap_rights_init(&fcaps1.fc_rights, CAP_EVENT, CAP_FCNTL,
CAP_FSTAT, CAP_READ);
fcaps1.fc_fcntls = CAP_FCNTL_SETFL;
cap_rights_init(&fcaps2.fc_rights, CAP_EVENT, CAP_FCNTL,
CAP_FSTAT, CAP_WRITE);
fcaps2.fc_fcntls = CAP_FCNTL_SETFL;
error = kern_pipe(td, fds, 0, &fcaps1, &fcaps2);
break;
case CLOUDABI_FILETYPE_SOCKET_DGRAM:
error = kern_socketpair(td, AF_UNIX, SOCK_DGRAM, 0, fds);
break;

4
sys/compat/linux/linux_file.c
View File

@ -1582,7 +1582,7 @@ linux_pipe(struct thread *td, struct linux_pipe_args *args)
printf(ARGS(pipe, "*"));
#endif
error = kern_pipe2(td, fildes, 0);
error = kern_pipe(td, fildes, 0, NULL, NULL);
if (error)
return (error);
@ -1609,7 +1609,7 @@ linux_pipe2(struct thread *td, struct linux_pipe2_args *args)
flags |= O_NONBLOCK;
if ((args->flags & LINUX_O_CLOEXEC) != 0)
flags |= O_CLOEXEC;
error = kern_pipe2(td, fildes, flags);
error = kern_pipe(td, fildes, flags, NULL, NULL);
if (error)
return (error);

22
sys/kern/sys_pipe.c
View File

@ -397,14 +397,8 @@ pipe_dtor(struct pipe *dpipe)
* the zone pick up the pieces via pipeclose().
*/
int
kern_pipe(struct thread *td, int fildes[2])
{
return (kern_pipe2(td, fildes, 0));
}
int
kern_pipe2(struct thread *td, int fildes[2], int flags)
kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1,
struct filecaps *fcaps2)
{
struct file *rf, *wf;
struct pipe *rpipe, *wpipe;
@ -414,13 +408,13 @@ kern_pipe2(struct thread *td, int fildes[2], int flags)
pipe_paircreate(td, &pp);
rpipe = &pp->pp_rpipe;
wpipe = &pp->pp_wpipe;
error = falloc(td, &rf, &fd, flags);
error = falloc_caps(td, &rf, &fd, flags, fcaps1);
if (error) {
pipeclose(rpipe);
pipeclose(wpipe);
return (error);
}
/* An extra reference on `rf' has been held for us by falloc(). */
/* An extra reference on `rf' has been held for us by falloc_caps(). */
fildes[0] = fd;
fflags = FREAD | FWRITE;
@ -434,7 +428,7 @@ kern_pipe2(struct thread *td, int fildes[2], int flags)
* side while we are blocked trying to allocate the write side.
*/
finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops);
error = falloc(td, &wf, &fd, flags);
error = falloc_caps(td, &wf, &fd, flags, fcaps2);
if (error) {
fdclose(td, rf, fildes[0]);
fdrop(rf, td);
@ -442,7 +436,7 @@ kern_pipe2(struct thread *td, int fildes[2], int flags)
pipeclose(wpipe);
return (error);
}
/* An extra reference on `wf' has been held for us by falloc(). */
/* An extra reference on `wf' has been held for us by falloc_caps(). */
finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops);
fdrop(wf, td);
fildes[1] = fd;
@ -458,7 +452,7 @@ sys_pipe(struct thread *td, struct pipe_args *uap)
int error;
int fildes[2];
error = kern_pipe(td, fildes);
error = kern_pipe(td, fildes, 0, NULL, NULL);
if (error)
return (error);
@ -475,7 +469,7 @@ sys_pipe2(struct thread *td, struct pipe2_args *uap)
if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK))
return (EINVAL);
error = kern_pipe2(td, fildes, uap->flags);
error = kern_pipe(td, fildes, uap->flags, NULL, NULL);
if (error)
return (error);
error = copyout(fildes, uap->fildes, 2 * sizeof(int));

5
sys/sys/syscallsubr.h
View File

@ -35,6 +35,7 @@
#include <sys/mount.h>
struct file;
struct filecaps;
enum idtype;
struct itimerval;
struct image_args;
@ -150,8 +151,8 @@ int kern_openat(struct thread *td, int fd, char *path,
enum uio_seg pathseg, int flags, int mode);
int kern_pathconf(struct thread *td, char *path, enum uio_seg pathseg,
int name, u_long flags);
int kern_pipe(struct thread *td, int fildes[2]);
int kern_pipe2(struct thread *td, int fildes[2], int flags);
int kern_pipe(struct thread *td, int fildes[2], int flags,
struct filecaps *fcaps1, struct filecaps *fcaps2);
int kern_poll(struct thread *td, struct pollfd *fds, u_int nfds,
struct timespec *tsp, sigset_t *uset);
int kern_posix_fadvise(struct thread *td, int fd, off_t offset, off_t len,