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.
The prot argument shall be PROT_NONE (no permissions at all) or the bitwise or of one or more of the following values:
- PROT_READ
-
The pages can be read.
- PROT_WRITE
-
The pages can be written.
- PROT_EXEC
-
The pages can be executed.
In addition to these standard protection flags, the FreeBSD implementation of mprotect() provides the ability to set the maximum protection of a region (which prevents mprotect from adding to the permissions later). This is accomplished by bitwise or'ing one or more PROT_ values wrapped in the PROT_MAX() macro into the prot argument.
RETURN VALUES
The mprotect() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.
ERRORS
The mprotect() system call will fail if:
- [EACCES]
-
The calling process was not allowed to change the protection to the value specified by the prot argument.
- [EINVAL]
-
The virtual address range specified by the addr and len arguments is not valid.
- [EINVAL]
-
The prot argument contains unhandled bits.
- [ENOTSUP]
-
The prot argument contains permissions which are not a subset of the specified maximum permissions.
SEE ALSO
HISTORY
The mprotect() system call was first documented in 4.2BSD and first appeared in 4.4BSD.
The PROT_MAX functionality was introduced in FreeBSD 13.