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fs/mmap: Return EACCES for incompatible file descriptors

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This commit is contained in:
Gustavo Henrique Nihei 2021-03-12 19:03:52 -03:00 committed by Xiang Xiao
parent fb7a5b86ca
commit c80cdf06c2
1 changed files with 30 additions and 0 deletions
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30
fs/mmap/fs_mmap.c
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@ -29,6 +29,7 @@
#include <sys/ioctl.h> #include <sys/ioctl.h>
#include <stdint.h> #include <stdint.h>
#include <errno.h> #include <errno.h>
#include <fcntl.h>
#include <debug.h> #include <debug.h>
#include <nuttx/kmalloc.h> #include <nuttx/kmalloc.h>
@ -95,6 +96,10 @@
* On success, mmap() returns a pointer to the mapped area. On error, the * On success, mmap() returns a pointer to the mapped area. On error, the
* value MAP_FAILED is returned, and errno is set appropriately. * value MAP_FAILED is returned, and errno is set appropriately.
* *
* EACCES
* The fd argument is not open for read, regardless of the
* protection specified, or fd is not open for write and PROT_WRITE
* was specified for a MAP_SHARED type mapping.
* ENOSYS * ENOSYS
* Returned if any of the unsupported mmap() features are attempted * Returned if any of the unsupported mmap() features are attempted
* EBADF * EBADF
@ -114,6 +119,7 @@ FAR void *mmap(FAR void *start, size_t length, int prot, int flags,
int fd, off_t offset) int fd, off_t offset)
{ {
FAR void *addr; FAR void *addr;
FAR struct file *filep;
int ret; int ret;
/* Since only a tiny subset of mmap() functionality, we have to verify many /* Since only a tiny subset of mmap() functionality, we have to verify many
@ -154,6 +160,30 @@ FAR void *mmap(FAR void *start, size_t length, int prot, int flags,
} }
#endif /* CONFIG_DEBUG_FEATURES */ #endif /* CONFIG_DEBUG_FEATURES */
if (fs_getfilep(fd, &filep) < 0)
{
ferr("ERROR: Invalid file descriptor, fd=%d\n", fd);
ret = -EBADF;
goto errout;
}
if ((filep->f_oflags & O_WROK) == 0 && prot == PROT_WRITE &&
(flags & MAP_SHARED) != 0)
{
ferr("ERROR: Unsupported options for read-only file descriptor,"
"fd=%d prot=%x flags=%04x\n", fd, prot, flags);
ret = -EACCES;
goto errout;
}
if ((filep->f_oflags & O_RDOK) == 0)
{
ferr("ERROR: File descriptor does not have read permission,"
"fd=%d\n", fd);
ret = -EACCES;
goto errout;
}
/* Check if we are just be asked to allocate memory, i.e., MAP_ANONYMOUS /* Check if we are just be asked to allocate memory, i.e., MAP_ANONYMOUS
* set meaning that the memory is not backed up from a file. The file * set meaning that the memory is not backed up from a file. The file
* descriptor should be -1 (or refer to opened /dev/zero) in this case. * descriptor should be -1 (or refer to opened /dev/zero) in this case.