MPROTECT(2) | System Calls Manual | MPROTECT(2)

# NAME

`mprotect` —
control the protection of pages

# LIBRARY

Standard C Library (libc, -lc)

# SYNOPSIS

`#include <sys/mman.h>`

int
`mprotect`(void *addr, size_t len, int prot);

# DESCRIPTION

The `mprotect` system call changes the specified pages to have protection prot. Not all implementations will guarantee protection on a page basis; the granularity of protection changes may be as large as an entire region.

The protections (region accessibility) are specified in the prot argument by OR'ing the following values:

`PROT_EXEC`
  Pages may be executed.
`PROT_READ`
  Pages may be read.
`PROT_WRITE`
  Pages may be written.
`PROT_NONE`
  Placeholder when requesting no access permission.

# RETURN VALUES

Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.

# ERRORS

[`EACCES`]
  A memory protection violation occurred.

  The `PROT_EXEC` flag was attempted on pages which belong to a file system mounted with the `NOEXEC` flag.

  The new protection is less restrictive than the protection originally set with mmap(2).

  PaX mprotect restrictions prohibit the requested protection.

[`EINVAL`]
  An invalid memory range, or invalid parameters were provided.
[`ENOMEM`]
  A resource shortage occurred while internally calling uvm_map_protect(9).

# SEE ALSO

madvise(2), mincore(2), msync(2), munmap(2)

# HISTORY

The `mprotect` function first appeared in 4.4BSD.

April 27, 2017 | NetBSD 9.3