989d921f5d
I'm very pleased to announce the release of our new website and documentation using the new toolchain with Hugo and AsciiDoctor. To get more information about the new toolchain please read the FreeBSD Documentation Project Primer[1], Hugo docs[2] and AsciiDoctor docs[3]. Acknowledgment: Benedict Reuschling <bcr@> Glen Barber <gjb@> Hiroki Sato <hrs@> Li-Wen Hsu <lwhsu@> Sean Chittenden <seanc@> The FreeBSD Foundation [1] https://docs.FreeBSD.org/en/books/fdp-primer/ [2] https://gohugo.io/documentation/ [3] https://docs.asciidoctor.org/home/ Approved by: doceng, core
48 lines
1.5 KiB
Diff
48 lines
1.5 KiB
Diff
Index: sys/kern/kern_exec.c
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===================================================================
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--- sys/kern/kern_exec.c (revision 197682)
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+++ sys/kern/kern_exec.c (working copy)
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@@ -104,6 +104,13 @@
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SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW,
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&ps_arg_cache_limit, 0, "");
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+SYSCTL_DECL(_security_bsd);
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+
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+static int map_at_zero = 1;
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+TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero);
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+SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0,
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+ "Permit processes to map an object at virtual address 0.");
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+
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static int
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sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)
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{
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@@ -914,7 +921,7 @@
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int error;
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struct proc *p = imgp->proc;
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struct vmspace *vmspace = p->p_vmspace;
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- vm_offset_t stack_addr;
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+ vm_offset_t sv_minuser, stack_addr;
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vm_map_t map;
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imgp->vmspace_destroyed = 1;
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@@ -928,14 +935,18 @@
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* not disrupted
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*/
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map = &vmspace->vm_map;
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- if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv->sv_minuser &&
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+ if (map_at_zero)
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+ sv_minuser = sv->sv_minuser;
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+ else
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+ sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE);
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+ if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser &&
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vm_map_max(map) == sv->sv_maxuser) {
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shmexit(vmspace);
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pmap_remove_pages(vmspace_pmap(vmspace), vm_map_min(map),
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vm_map_max(map));
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vm_map_remove(map, vm_map_min(map), vm_map_max(map));
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} else {
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- vmspace_exec(p, sv->sv_minuser, sv->sv_maxuser);
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+ vmspace_exec(p, sv_minuser, sv->sv_maxuser);
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vmspace = p->p_vmspace;
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map = &vmspace->vm_map;
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}
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