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Ignore the error from pipespace_new when creating a pipe.

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It can fail if pipe map is exhausted (as a result of too many pipes created),
but it is not fatal and could be provoked by unprivileged users. The only
consequence is worse performance with given pipe.

Reported by:	ivoras
Suggested by:	kib
MFC after:	1 week
This commit is contained in:
Mateusz Guzik 2014-05-02 00:52:13 +00:00
parent 7d567ed66f
commit 183870cf75
3 changed files with 21 additions and 32 deletions
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4
sys/fs/fifofs/fifo_vnops.c
View File

@ -146,9 +146,7 @@ fifo_open(ap)
if (fp == NULL || (ap->a_mode & FEXEC) != 0)
return (EINVAL);
if ((fip = vp->v_fifoinfo) == NULL) {
error = pipe_named_ctor(&fpipe, td);
if (error != 0)
return (error);
pipe_named_ctor(&fpipe, td);
fip = malloc(sizeof(*fip), M_VNODE, M_WAITOK);
fip->fi_pipe = fpipe;
fpipe->pipe_wgen = fip->fi_readers = fip->fi_writers = 0;

47
sys/kern/sys_pipe.c
View File

@ -221,8 +221,8 @@ SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
static void pipeinit(void *dummy __unused);
static void pipeclose(struct pipe *cpipe);
static void pipe_free_kmem(struct pipe *cpipe);
static int pipe_create(struct pipe *pipe, int backing);
static int pipe_paircreate(struct thread *td, struct pipepair **p_pp);
static void pipe_create(struct pipe *pipe, int backing);
static void pipe_paircreate(struct thread *td, struct pipepair **p_pp);
static __inline int pipelock(struct pipe *cpipe, int catch);
static __inline void pipeunlock(struct pipe *cpipe);
#ifndef PIPE_NODIRECT
@ -331,12 +331,11 @@ pipe_zone_fini(void *mem, int size)
mtx_destroy(&pp->pp_mtx);
}
static int
static void
pipe_paircreate(struct thread *td, struct pipepair **p_pp)
{
struct pipepair *pp;
struct pipe *rpipe, *wpipe;
int error;
*p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK);
#ifdef MAC
@ -355,30 +354,21 @@ pipe_paircreate(struct thread *td, struct pipepair **p_pp)
knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
/* Only the forward direction pipe is backed by default */
if ((error = pipe_create(rpipe, 1)) != 0 ||
(error = pipe_create(wpipe, 0)) != 0) {
pipeclose(rpipe);
pipeclose(wpipe);
return (error);
}
pipe_create(rpipe, 1);
pipe_create(wpipe, 0);
rpipe->pipe_state |= PIPE_DIRECTOK;
wpipe->pipe_state |= PIPE_DIRECTOK;
return (0);
}
int
void
pipe_named_ctor(struct pipe **ppipe, struct thread *td)
{
struct pipepair *pp;
int error;
error = pipe_paircreate(td, &pp);
if (error != 0)
return (error);
pipe_paircreate(td, &pp);
pp->pp_rpipe.pipe_state |= PIPE_NAMED;
*ppipe = &pp->pp_rpipe;
return (0);
}
void
@ -419,9 +409,7 @@ kern_pipe2(struct thread *td, int fildes[2], int flags)
int fd, fflags, error;
fdp = td->td_proc->p_fd;
error = pipe_paircreate(td, &pp);
if (error != 0)
return (error);
pipe_paircreate(td, &pp);
rpipe = &pp->pp_rpipe;
wpipe = &pp->pp_wpipe;
error = falloc(td, &rf, &fd, flags);
@ -642,24 +630,27 @@ pipeselwakeup(cpipe)
* Initialize and allocate VM and memory for pipe. The structure
* will start out zero'd from the ctor, so we just manage the kmem.
*/
static int
static void
pipe_create(pipe, backing)
struct pipe *pipe;
int backing;
{
int error;
if (backing) {
/*
* Note that these functions can fail if pipe map is exhausted
* (as a result of too many pipes created), but we ignore the
* error as it is not fatal and could be provoked by
* unprivileged users. The only consequence is worse performance
* with given pipe.
*/
if (amountpipekva > maxpipekva / 2)
error = pipespace_new(pipe, SMALL_PIPE_SIZE);
(void)pipespace_new(pipe, SMALL_PIPE_SIZE);
else
error = pipespace_new(pipe, PIPE_SIZE);
} else {
/* If we're not backing this pipe, no need to do anything. */
error = 0;
(void)pipespace_new(pipe, PIPE_SIZE);
}
pipe->pipe_ino = -1;
return (error);
}
/* ARGSUSED */

2
sys/sys/pipe.h
View File

@ -142,6 +142,6 @@ struct pipepair {
#define PIPE_LOCK_ASSERT(pipe, type) mtx_assert(PIPE_MTX(pipe), (type))
void pipe_dtor(struct pipe *dpipe);
int pipe_named_ctor(struct pipe **ppipe, struct thread *td);
void pipe_named_ctor(struct pipe **ppipe, struct thread *td);
void pipeselwakeup(struct pipe *cpipe);
#endif /* !_SYS_PIPE_H_ */