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author | dillon <dillon@FreeBSD.org> | 2002-12-16 19:24:43 +0000 |
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committer | dillon <dillon@FreeBSD.org> | 2002-12-16 19:24:43 +0000 |
commit | be3db49c80fb516ad39e2306c2dd94eb57f1fe16 (patch) | |
tree | 62395793dfc1ca744a98bca2261e363d7c975367 /sys | |
parent | 1696b05046d85a2bd2206eddc6e04c79ac567c2b (diff) | |
download | FreeBSD-src-be3db49c80fb516ad39e2306c2dd94eb57f1fe16.zip FreeBSD-src-be3db49c80fb516ad39e2306c2dd94eb57f1fe16.tar.gz |
Change the way ELF coredumps are handled. Instead of unconditionally
skipping read-only pages, which can result in valuable non-text-related
data not getting dumped, the ELF loader and the dynamic loader now mark
read-only text pages NOCORE and the coredump code only checks (primarily) for
complete inaccessibility of the page or NOCORE being set.
Certain applications which map large amounts of read-only data will
produce much larger cores. A new sysctl has been added,
debug.elf_legacy_coredump, which will revert to the old behavior.
This commit represents collaborative work by all parties involved.
The PR contains a program demonstrating the problem.
PR: kern/45994
Submitted by: "Peter Edwards" <pmedwards@eircom.net>, Archie Cobbs <archie@dellroad.org>
Reviewed by: jdp, dillon
MFC after: 7 days
Diffstat (limited to 'sys')
-rw-r--r-- | sys/kern/imgact_elf.c | 42 | ||||
-rw-r--r-- | sys/vm/vm.h | 1 |
2 files changed, 32 insertions, 11 deletions
diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c index 27bcfbe..44d4bf0 100644 --- a/sys/kern/imgact_elf.c +++ b/sys/kern/imgact_elf.c @@ -87,6 +87,9 @@ SYSCTL_INT(_debug, OID_AUTO, elf32_trace, CTLFLAG_RW, &elf_trace, 0, ""); #else SYSCTL_INT(_debug, OID_AUTO, elf64_trace, CTLFLAG_RW, &elf_trace, 0, ""); #endif +static int elf_legacy_coredump = 0; +SYSCTL_INT(_debug, OID_AUTO, elf_legacy_coredump, CTLFLAG_RW, + &elf_legacy_coredump, 0, ""); static Elf_Brandinfo *elf_brand_list[MAX_BRANDS]; extern int fallback_elf_brand; @@ -349,7 +352,7 @@ __elfN(load_section)(struct proc *p, struct vmspace *vmspace, { size_t map_len; vm_offset_t map_addr; - int error, rv; + int error, rv, cow; size_t copy_len; vm_offset_t file_addr; vm_offset_t data_buf = 0; @@ -392,6 +395,11 @@ __elfN(load_section)(struct proc *p, struct vmspace *vmspace, if (map_len != 0) { vm_object_reference(object); + + /* cow flags: don't dump readonly sections in core */ + cow = MAP_COPY_ON_WRITE | MAP_PREFAULT | + (prot & VM_PROT_WRITE ? 0 : MAP_DISABLE_COREDUMP); + rv = __elfN(map_insert)(&vmspace->vm_map, object, file_addr, /* file offset */ @@ -399,7 +407,7 @@ __elfN(load_section)(struct proc *p, struct vmspace *vmspace, map_addr + map_len,/* virtual end */ prot, VM_PROT_ALL, - MAP_COPY_ON_WRITE | MAP_PREFAULT); + cow); if (rv != KERN_SUCCESS) { vm_object_deallocate(object); return (EINVAL); @@ -1042,17 +1050,29 @@ each_writable_segment(p, func, closure) entry = entry->next) { vm_object_t obj; - if ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) || - (entry->protection & (VM_PROT_READ|VM_PROT_WRITE)) != - (VM_PROT_READ|VM_PROT_WRITE)) - continue; + /* + * Don't dump inaccessible mappings, deal with legacy + * coredump mode. + * + * Note that read-only segments related to the elf binary + * are marked MAP_ENTRY_NOCOREDUMP now so we no longer + * need to arbitrarily ignore such segments. + */ + if (elf_legacy_coredump) { + if ((entry->protection & VM_PROT_RW) != VM_PROT_RW) + continue; + } else { + if ((entry->protection & VM_PROT_ALL) == 0) + continue; + } /* - ** Dont include memory segment in the coredump if - ** MAP_NOCORE is set in mmap(2) or MADV_NOCORE in - ** madvise(2). - */ - if (entry->eflags & MAP_ENTRY_NOCOREDUMP) + * Dont include memory segment in the coredump if + * MAP_NOCORE is set in mmap(2) or MADV_NOCORE in + * madvise(2). Do not dump submaps (i.e. parts of the + * kernel map). + */ + if (entry->eflags & (MAP_ENTRY_NOCOREDUMP|MAP_ENTRY_IS_SUB_MAP)) continue; if ((obj = entry->object.vm_object) == NULL) diff --git a/sys/vm/vm.h b/sys/vm/vm.h index ffbcd48..55818ef 100644 --- a/sys/vm/vm.h +++ b/sys/vm/vm.h @@ -81,6 +81,7 @@ typedef u_char vm_prot_t; /* protection codes */ #define VM_PROT_OVERRIDE_WRITE ((vm_prot_t) 0x08) /* copy-on-write */ #define VM_PROT_ALL (VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE) +#define VM_PROT_RW (VM_PROT_READ|VM_PROT_WRITE) #define VM_PROT_DEFAULT VM_PROT_ALL union vm_map_object; |