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| author | Frans Kaashoek <kaashoek@mit.edu> | 2022-08-12 13:22:10 -0400 |
|---|---|---|
| committer | Frans Kaashoek <kaashoek@mit.edu> | 2022-08-12 13:22:10 -0400 |
| commit | 899cc02660232092209a5db57b326ab7b49813dd (patch) | |
| tree | abde95c343fb06294fba1c30036a3d6564602693 | |
| parent | 8f58cc7df99e9f697ca3843886802ecab5cb8991 (diff) | |
| download | xv6-labs-899cc02660232092209a5db57b326ab7b49813dd.tar.gz xv6-labs-899cc02660232092209a5db57b326ab7b49813dd.tar.bz2 xv6-labs-899cc02660232092209a5db57b326ab7b49813dd.zip | |
Experiment with being more precise setting permissions for user pages.
Growing adds R|W pages (without X). Exec() marks the stack only R|W.
Probably could setup permissions for text and data better if we call
ld with --no-omagic instead of -N.
| -rw-r--r-- | kernel/defs.h | 2 | ||||
| -rw-r--r-- | kernel/exec.c | 4 | ||||
| -rw-r--r-- | kernel/proc.c | 2 | ||||
| -rw-r--r-- | kernel/vm.c | 4 |
4 files changed, 6 insertions, 6 deletions
diff --git a/kernel/defs.h b/kernel/defs.h index 62b9292..5cf2de2 100644 --- a/kernel/defs.h +++ b/kernel/defs.h @@ -160,7 +160,7 @@ void kvmmap(pagetable_t, uint64, uint64, uint64, int); int mappages(pagetable_t, uint64, uint64, uint64, int); pagetable_t uvmcreate(void); void uvmfirst(pagetable_t, uchar *, uint); -uint64 uvmalloc(pagetable_t, uint64, uint64); +uint64 uvmalloc(pagetable_t, uint64, uint64, int); uint64 uvmdealloc(pagetable_t, uint64, uint64); int uvmcopy(pagetable_t, pagetable_t, uint64); void uvmfree(pagetable_t, uint64); diff --git a/kernel/exec.c b/kernel/exec.c index 09b4bdc..3c468e1 100644 --- a/kernel/exec.c +++ b/kernel/exec.c @@ -49,7 +49,7 @@ exec(char *path, char **argv) if(ph.vaddr + ph.memsz < ph.vaddr) goto bad; uint64 sz1; - if((sz1 = uvmalloc(pagetable, sz, ph.vaddr + ph.memsz)) == 0) + if((sz1 = uvmalloc(pagetable, sz, ph.vaddr + ph.memsz, PTE_X|PTE_W)) == 0) goto bad; sz = sz1; if((ph.vaddr % PGSIZE) != 0) @@ -69,7 +69,7 @@ exec(char *path, char **argv) // Use the second as the user stack. sz = PGROUNDUP(sz); uint64 sz1; - if((sz1 = uvmalloc(pagetable, sz, sz + 2*PGSIZE)) == 0) + if((sz1 = uvmalloc(pagetable, sz, sz + 2*PGSIZE, PTE_W)) == 0) goto bad; sz = sz1; uvmclear(pagetable, sz-2*PGSIZE); diff --git a/kernel/proc.c b/kernel/proc.c index 580b3b6..0fa6a2c 100644 --- a/kernel/proc.c +++ b/kernel/proc.c @@ -264,7 +264,7 @@ growproc(int n) sz = p->sz; if(n > 0){ - if((sz = uvmalloc(p->pagetable, sz, sz + n)) == 0) { + if((sz = uvmalloc(p->pagetable, sz, sz + n, PTE_W)) == 0) { return -1; } } else if(n < 0){ diff --git a/kernel/vm.c b/kernel/vm.c index 3c6f295..284b72d 100644 --- a/kernel/vm.c +++ b/kernel/vm.c @@ -218,7 +218,7 @@ uvmfirst(pagetable_t pagetable, uchar *src, uint sz) // Allocate PTEs and physical memory to grow process from oldsz to // newsz, which need not be page aligned. Returns new size or 0 on error. uint64 -uvmalloc(pagetable_t pagetable, uint64 oldsz, uint64 newsz) +uvmalloc(pagetable_t pagetable, uint64 oldsz, uint64 newsz, int xperm) { char *mem; uint64 a; @@ -234,7 +234,7 @@ uvmalloc(pagetable_t pagetable, uint64 oldsz, uint64 newsz) return 0; } memset(mem, 0, PGSIZE); - if(mappages(pagetable, a, PGSIZE, (uint64)mem, PTE_W|PTE_X|PTE_R|PTE_U) != 0){ + if(mappages(pagetable, a, PGSIZE, (uint64)mem, PTE_R|PTE_U|xperm) != 0){ kfree(mem); uvmdealloc(pagetable, a, oldsz); return 0; |