From 40b60cc1dbed3ab3f742177374300f3ba87eb550 Mon Sep 17 00:00:00 2001 From: Szabolcs Nagy Date: Fri, 21 Oct 2022 12:38:26 +0100 Subject: [PATCH] cheri: elf: Fix segment mapping permissions Ensure mmap returns pointers with RWX permission covering all segments. These pointers later get restricted to RX and RW permission. --- elf/dl-map-segments.h | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/elf/dl-map-segments.h b/elf/dl-map-segments.h index ce51585ce4..e25fb579df 100644 --- a/elf/dl-map-segments.h +++ b/elf/dl-map-segments.h @@ -22,6 +22,13 @@ # include #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)