view tests/test-audit-path.t @ 46607:e9901d01d135

revlog: add a mechanism to verify expected file position before appending

If someone uses `hg debuglocks`, or some non-hg process writes to the .hg
directory without respecting the locks, or if the repo's on a networked
filesystem, it's possible for the revlog code to write out corrupted data.

The form of this corruption can vary depending on what data was written and how
that happened. We are in the "networked filesystem" case (though I've had users
also do this to themselves with the "`hg debuglocks`" scenario), and most often
see this with the changelog. What ends up happening is we produce two items
(let's call them rev1 and rev2) in the .i file that have the same linkrev,
baserev, and offset into the .d file, while the data in the .d file is appended
properly. rev2's compressed_size is accurate for rev2, but when we go to
decompress the data in the .d file, we use the offset that's recorded in the
index file, which is the same as rev1, and attempt to decompress
rev2.compressed_size bytes of rev1's data. This usually does not succeed. :)

When using inline data, this also fails, though I haven't investigated why too
closely. This shows up as a "patch decode" error. I believe what's happening
there is that we're basically ignoring the offset field, getting the data
properly, but since baserev != rev, it thinks this is a delta based on rev
(instead of a full text) and can't actually apply it as such.

For now, I'm going to make this an optional component and default it to entirely
off. I may increase the default severity of this in the future, once I've
enabled it for my users and we gain more experience with it. Luckily, most of my
users have a versioned filesystem and can roll back to before the corruption has
been written, it's just a hassle to do so and not everyone knows how (so it's a
support burden). Users on other filesystems will not have that luxury, and this
can cause them to have a corrupted repository that they are unlikely to know how
to resolve, and they'll see this as a data-loss event. Refusing to create the
corruption is a much better user experience.

This mechanism is not perfect. There may be false-negatives (racy writes that
are not detected). There should not be any false-positives (non-racy writes that
are detected as such). This is not a mechanism that makes putting a repo on a
networked filesystem "safe" or "supported", just *less* likely to cause
corruption.

Differential Revision: https://phab.mercurial-scm.org/D9952

The simple store doesn't escape paths robustly and can't store paths
with periods, etc. So much of this test fails with it.
#require no-reposimplestore

  $ hg init

audit of .hg

  $ hg add .hg/00changelog.i
  abort: path contains illegal component: .hg/00changelog.i
  [255]

#if symlink

Symlinks

  $ mkdir a
  $ echo a > a/a
  $ hg ci -Ama
  adding a/a
  $ ln -s a b
  $ echo b > a/b
  $ hg add b/b
  abort: path 'b/b' traverses symbolic link 'b'
  [255]
  $ hg add b

should still fail - maybe

  $ hg add b/b
  abort: path 'b/b' traverses symbolic link 'b'
  [255]

  $ hg commit -m 'add symlink b'


Test symlink traversing when accessing history:
-----------------------------------------------

(build a changeset where the path exists as a directory)

  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mkdir b
  $ echo c > b/a
  $ hg add b/a
  $ hg ci -m 'add directory b'
  created new head

Test that hg cat does not do anything wrong the working copy has 'b' as directory

  $ hg cat b/a
  c
  $ hg cat -r "desc(directory)" b/a
  c
  $ hg cat -r "desc(symlink)" b/a
  b/a: no such file in rev bc151a1f53bd
  [1]

Test that hg cat does not do anything wrong the working copy has 'b' as a symlink (issue4749)

  $ hg up 'desc(symlink)'
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg cat b/a
  b/a: no such file in rev bc151a1f53bd
  [1]
  $ hg cat -r "desc(directory)" b/a
  c
  $ hg cat -r "desc(symlink)" b/a
  b/a: no such file in rev bc151a1f53bd
  [1]

#endif


unbundle tampered bundle

  $ hg init target
  $ cd target
  $ hg unbundle "$TESTDIR/bundles/tampered.hg"
  adding changesets
  adding manifests
  adding file changes
  added 5 changesets with 6 changes to 6 files (+4 heads)
  new changesets b7da9bf6b037:fc1393d727bc (5 drafts)
  (run 'hg heads' to see heads, 'hg merge' to merge)

attack .hg/test

  $ hg manifest -r0
  .hg/test
  $ hg update -Cr0
  abort: path contains illegal component: .hg/test
  [255]

attack foo/.hg/test

  $ hg manifest -r1
  foo/.hg/test
  $ hg update -Cr1
  abort: path 'foo/.hg/test' is inside nested repo 'foo'
  [255]

attack back/test where back symlinks to ..

  $ hg manifest -r2
  back
  back/test
#if symlink
  $ hg update -Cr2
  abort: path 'back/test' traverses symbolic link 'back'
  [255]
#else
('back' will be a file and cause some other system specific error)
  $ hg update -Cr2
  abort: $TESTTMP/target/back/test: $ENOTDIR$
  [255]
#endif

attack ../test

  $ hg manifest -r3
  ../test
  $ mkdir ../test
  $ echo data > ../test/file
  $ hg update -Cr3
  abort: path contains illegal component: ../test
  [255]
  $ cat ../test/file
  data

attack /tmp/test

  $ hg manifest -r4
  /tmp/test
  $ hg update -Cr4
  abort: path contains illegal component: /tmp/test
  [255]

  $ cd ..

Test symlink traversal on merge:
--------------------------------

#if symlink

set up symlink hell

  $ mkdir merge-symlink-out
  $ hg init merge-symlink
  $ cd merge-symlink
  $ touch base
  $ hg commit -qAm base
  $ ln -s ../merge-symlink-out a
  $ hg commit -qAm 'symlink a -> ../merge-symlink-out'
  $ hg up -q 0
  $ mkdir a
  $ touch a/poisoned
  $ hg commit -qAm 'file a/poisoned'
  $ hg log -G -T '{rev}: {desc}\n'
  @  2: file a/poisoned
  |
  | o  1: symlink a -> ../merge-symlink-out
  |/
  o  0: base
  

try trivial merge

  $ hg up -qC 1
  $ hg merge 2
  abort: path 'a/poisoned' traverses symbolic link 'a'
  [255]

try rebase onto other revision: cache of audited paths should be discarded,
and the rebase should fail (issue5628)

  $ hg up -qC 2
  $ hg rebase -s 2 -d 1 --config extensions.rebase=
  rebasing 2:e73c21d6b244 tip "file a/poisoned"
  abort: path 'a/poisoned' traverses symbolic link 'a'
  [255]
  $ ls ../merge-symlink-out

  $ cd ..

Test symlink traversal on update:
---------------------------------

  $ mkdir update-symlink-out
  $ hg init update-symlink
  $ cd update-symlink
  $ ln -s ../update-symlink-out a
  $ hg commit -qAm 'symlink a -> ../update-symlink-out'
  $ hg rm a
  $ mkdir a && touch a/b
  $ hg ci -qAm 'file a/b' a/b
  $ hg up -qC 0
  $ hg rm a
  $ mkdir a && touch a/c
  $ hg ci -qAm 'rm a, file a/c'
  $ hg log -G -T '{rev}: {desc}\n'
  @  2: rm a, file a/c
  |
  | o  1: file a/b
  |/
  o  0: symlink a -> ../update-symlink-out
  

try linear update where symlink already exists:

  $ hg up -qC 0
  $ hg up 1
  abort: path 'a/b' traverses symbolic link 'a'
  [255]

try linear update including symlinked directory and its content: paths are
audited first by calculateupdates(), where no symlink is created so both
'a' and 'a/b' are taken as good paths. still applyupdates() should fail.

  $ hg up -qC null
  $ hg up 1
  abort: path 'a/b' traverses symbolic link 'a'
  [255]
  $ ls ../update-symlink-out

try branch update replacing directory with symlink, and its content: the
path 'a' is audited as a directory first, which should be audited again as
a symlink.

  $ rm -f a
  $ hg up -qC 2
  $ hg up 1
  abort: path 'a/b' traverses symbolic link 'a'
  [255]
  $ ls ../update-symlink-out

  $ cd ..

#endif