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Make handling of mmap()'s prot argument more strict.

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- Make the system call fail if prot contains bits other than read, write
  and exec.
- Similar to OpenBSD's W^X, don't allow write and exec to be set at the
  same time. I'd like to see for now what happens if we enforce this
  policy unconditionally. If it turns out that this is far too strict,
  we'll loosen this requirement.
This commit is contained in:
ed 2016-02-23 09:22:00 +00:00
parent e53b711aeb
commit 247b18c729
1 changed files with 27 additions and 9 deletions
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36
sys/compat/cloudabi/cloudabi_mem.c
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@ -35,18 +35,26 @@ __FBSDID("$FreeBSD$");
/* Converts CloudABI's memory protection flags to FreeBSD's. */
static int
convert_mprot(cloudabi_mprot_t in)
convert_mprot(cloudabi_mprot_t in, int *out)
{
int out;
out = 0;
/* Unknown protection flags. */
if ((in & ~(CLOUDABI_PROT_EXEC | CLOUDABI_PROT_WRITE |
CLOUDABI_PROT_READ)) != 0)
return (ENOTSUP);
/* W^X: Write and exec cannot be enabled at the same time. */
if ((in & (CLOUDABI_PROT_EXEC | CLOUDABI_PROT_WRITE)) ==
(CLOUDABI_PROT_EXEC | CLOUDABI_PROT_WRITE))
return (ENOTSUP);
*out = 0;
if (in & CLOUDABI_PROT_EXEC)
out |= PROT_EXEC;
*out |= PROT_EXEC;
if (in & CLOUDABI_PROT_WRITE)
out |= PROT_WRITE;
*out |= PROT_WRITE;
if (in & CLOUDABI_PROT_READ)
out |= PROT_READ;
return (out);
*out |= PROT_READ;
return (0);
}
int
@ -98,10 +106,10 @@ cloudabi_sys_mem_map(struct thread *td, struct cloudabi_sys_mem_map_args *uap)
struct mmap_args mmap_args = {
.addr = uap->addr,
.len = uap->len,
.prot = convert_mprot(uap->prot),
.fd = uap->fd,
.pos = uap->off
};
int error;
/* Translate flags. */
if (uap->flags & CLOUDABI_MAP_ANON)
@ -113,6 +121,11 @@ cloudabi_sys_mem_map(struct thread *td, struct cloudabi_sys_mem_map_args *uap)
if (uap->flags & CLOUDABI_MAP_SHARED)
mmap_args.flags |= MAP_SHARED;
/* Translate protection. */
error = convert_mprot(uap->prot, &mmap_args.prot);
if (error != 0)
return (error);
return (sys_mmap(td, &mmap_args));
}
@ -123,8 +136,13 @@ cloudabi_sys_mem_protect(struct thread *td,
struct mprotect_args mprotect_args = {
.addr = uap->addr,
.len = uap->len,
.prot = convert_mprot(uap->prot),
};
int error;
/* Translate protection. */
error = convert_mprot(uap->prot, &mprotect_args.prot);
if (error != 0)
return (error);
return (sys_mprotect(td, &mprotect_args));
}