common: use ptrace if yama blocked process_vm_readv/writev #280
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Having sysctl kernel.yama.ptrace_scope=1, one may only call ptrace attach on direct descendants. The same restriction is also checked for `process_vm_readv`/`writev` and certain procfs files. However, if an intermediate parent process already exited, we could end up with a grandchild that we're still ptracing but isn't our descendant, so we can't use the `process_vm` functions anymore -> `EPERM`. We already had a fallback here for `EFAULT`, to just use `ptrace` memory access, so use the same fallback after `EPERM` too. Fixes dyninst#274.
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Did Jenkins actually test this? I found testsuite-build #97, but it doesn't look like it ran anything. Anyway, I'm not worried about it -- I think this change has very low risk. |
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It did, but it failed to aggregate; the results look clean. May as well merge the proccontrol fixes in whatever order is best, Josh; they should help clean things up for the other testing we're doing on parsing fixes etc. |
wrwilliams
approved these changes
Nov 30, 2016
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Ok, thanks! They're all touching distinct lines, so I'll just merge them in submission order. |
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Having sysctl kernel.yama.ptrace_scope=1, one may only call ptrace
attach on direct descendants. The same restriction is also checked for
process_vm_readv/writevand certain procfs files. However, if anintermediate parent process already exited, we could end up with a
grandchild that we're still ptracing but isn't our descendant, so we
can't use the
process_vmfunctions anymore ->EPERM.We already had a fallback here for
EFAULT, to just useptracememoryaccess, so use the same fallback after
EPERMtoo.Fixes #274.