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cheri: elf: Fix segment mapping permissions

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Ensure mmap returns pointers with RWX permission covering all segments.
These pointers later get restricted to RX and RW permission.
This commit is contained in:
Szabolcs Nagy 2022-10-21 12:38:26 +01:00
parent 44283b4f2f
commit 40b60cc1db
1 changed files with 13 additions and 4 deletions
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17
elf/dl-map-segments.h
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@ -22,6 +22,13 @@
# include <cheri_perms.h>
#endif
/* Allow RWX mprotect later, on CHERI this means RWX capability permission. */
#ifdef PROT_MAX
# define PROT_MAX_RWX PROT_MAX (PROT_READ | PROT_WRITE | PROT_EXEC)
#else
# define PROT_MAX_RWX 0
#endif
/* Map a segment and align it properly. */
static __always_inline elfptr_t
@ -29,7 +36,8 @@ _dl_map_segment (const struct loadcmd *c, ElfW(Addr) mappref,
const size_t maplength, int fd)
{
if (__glibc_likely (c->mapalign <= GLRO(dl_pagesize)))
return (elfptr_t) __mmap ((void *) mappref, maplength, c->prot,
return (elfptr_t) __mmap ((void *) mappref, maplength,
c->prot|PROT_MAX_RWX,
MAP_COPY|MAP_FILE, fd, c->mapoff);
/* If the segment alignment > the page size, allocate enough space to
@ -38,7 +46,7 @@ _dl_map_segment (const struct loadcmd *c, ElfW(Addr) mappref,
? (maplength + c->mapalign)
: (2 * c->mapalign));
elfptr_t map_start = (elfptr_t) __mmap ((void *) mappref, maplen,
PROT_NONE,
PROT_NONE|PROT_MAX_RWX,
MAP_ANONYMOUS|MAP_PRIVATE,
-1, 0);
if (__glibc_unlikely ((void *) map_start == MAP_FAILED))
@ -46,7 +54,7 @@ _dl_map_segment (const struct loadcmd *c, ElfW(Addr) mappref,
elfptr_t map_start_aligned = ALIGN_UP (map_start, c->mapalign);
map_start_aligned = (elfptr_t) __mmap ((void *) map_start_aligned,
maplength, c->prot,
maplength, c->prot|PROT_MAX_RWX,
MAP_COPY|MAP_FILE|MAP_FIXED,
fd, c->mapoff);
if (__glibc_unlikely ((void *) map_start_aligned == MAP_FAILED))
@ -137,7 +145,8 @@ _dl_map_segments (struct link_map *l, int fd,
else
{
/* Need a single capability to cover all load segments. */
void *p = __mmap ((void *) c->mapstart, maplength, c->prot,
void *p = __mmap ((void *) c->mapstart, maplength,
c->prot|PROT_MAX_RWX,
MAP_FIXED|MAP_COPY|MAP_FILE,
fd, c->mapoff);
if (p == MAP_FAILED)