view tests/test-convert-hg-startrev.t @ 30766:d7bf7d2bd5ab

hgweb: support Content Security Policy

Content-Security-Policy (CSP) is a web security feature that allows
servers to declare what loaded content is allowed to do. For example,
a policy can prevent loading of images, JavaScript, CSS, etc unless
the source of that content is whitelisted (by hostname, URI scheme,
hashes of content, etc). It's a nifty security feature that provides
extra mitigation against some attacks, notably XSS.

Mitigation against these attacks is important for Mercurial because
hgweb renders repository data, which is commonly untrusted. While we
make attempts to escape things, etc, there's the possibility that
malicious data could be injected into the site content. If this happens
today, the full power of the web browser is available to that
malicious content. A restrictive CSP policy (defined by the server
operator and sent in an HTTP header which is outside the control of
malicious content), could restrict browser capabilities and mitigate
security problems posed by malicious data.

CSP works by emitting an HTTP header declaring the policy that browsers
should apply. Ideally, this header would be emitted by a layer above
Mercurial (likely the HTTP server doing the WSGI "proxying"). This
works for some CSP policies, but not all.

For example, policies to allow inline JavaScript may require setting
a "nonce" attribute on <script>. This attribute value must be unique
and non-guessable. And, the value must be present in the HTTP header
and the HTML body. This means that coordinating the value between
Mercurial and another HTTP server could be difficult: it is much
easier to generate and emit the nonce in a central location.

This commit introduces support for emitting a
Content-Security-Policy header from hgweb. A config option defines
the header value. If present, the header is emitted. A special
"%nonce%" syntax in the value triggers generation of a nonce and
inclusion in <script> elements in templates. The inclusion of a
nonce does not occur unless "%nonce%" is present. This makes this
commit completely backwards compatible and the feature opt-in.

The nonce is a type 4 UUID, which is the flavor that is randomly
generated. It has 122 random bits, which should be plenty to satisfy
the guarantees of a nonce.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > convert =
  > [convert]
  > hg.saverev = yes
  > EOF

  $ glog()
  > {
  >     hg -R "$1" log -G --template '{rev} "{desc}" files: {files}\n'
  > }

  $ hg init source
  $ cd source

  $ echo a > a
  $ echo b > b
  $ echo f > f
  $ hg ci -d '0 0' -qAm '0: add a b f'
  $ echo c > c
  $ hg move f d
  $ hg ci -d '1 0' -qAm '1: add c, move f to d'
  $ hg copy a e
  $ echo b >> b
  $ hg ci -d '2 0' -qAm '2: copy e from a, change b'
  $ hg up -C 0
  2 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ echo a >> a
  $ hg ci -d '3 0' -qAm '3: change a'
  $ hg merge
  merging a and e to e
  3 files updated, 1 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -d '4 0' -qAm '4: merge 2 and 3'
  $ echo a >> a
  $ hg ci -d '5 0' -qAm '5: change a'
  $ cd ..

Convert from null revision

  $ hg convert --config convert.hg.startrev=null source full
  initializing destination full repository
  scanning source...
  sorting...
  converting...
  5 0: add a b f
  4 1: add c, move f to d
  3 2: copy e from a, change b
  2 3: change a
  1 4: merge 2 and 3
  0 5: change a

  $ glog full
  o  5 "5: change a" files: a
  |
  o    4 "4: merge 2 and 3" files: e f
  |\
  | o  3 "3: change a" files: a
  | |
  o |  2 "2: copy e from a, change b" files: b e
  | |
  o |  1 "1: add c, move f to d" files: c d f
  |/
  o  0 "0: add a b f" files: a b f
  
  $ rm -Rf full

Convert from zero revision

  $ hg convert --config convert.hg.startrev=0 source full
  initializing destination full repository
  scanning source...
  sorting...
  converting...
  5 0: add a b f
  4 1: add c, move f to d
  3 2: copy e from a, change b
  2 3: change a
  1 4: merge 2 and 3
  0 5: change a

  $ glog full
  o  5 "5: change a" files: a
  |
  o    4 "4: merge 2 and 3" files: e f
  |\
  | o  3 "3: change a" files: a
  | |
  o |  2 "2: copy e from a, change b" files: b e
  | |
  o |  1 "1: add c, move f to d" files: c d f
  |/
  o  0 "0: add a b f" files: a b f
  
Convert from merge parent

  $ hg convert --config convert.hg.startrev=1 source conv1
  initializing destination conv1 repository
  scanning source...
  sorting...
  converting...
  3 1: add c, move f to d
  2 2: copy e from a, change b
  1 4: merge 2 and 3
  0 5: change a

  $ glog conv1
  o  3 "5: change a" files: a
  |
  o  2 "4: merge 2 and 3" files: a e
  |
  o  1 "2: copy e from a, change b" files: b e
  |
  o  0 "1: add c, move f to d" files: a b c d
  
  $ cd conv1
  $ hg up -q

Check copy preservation

  $ hg st -C --change 2 e
  M e
  $ hg st -C --change 1 e
  A e
    a
  $ hg st -C --change 0 a
  A a

(It seems like a bug in log that the following doesn't show rev 1.)

  $ hg log --follow --copies e
  changeset:   2:82bbac3d2cf4
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     4: merge 2 and 3
  
  changeset:   0:23c3be426dce
  user:        test
  date:        Thu Jan 01 00:00:01 1970 +0000
  summary:     1: add c, move f to d
  
Check copy removal on missing parent

  $ hg log --follow --copies d
  changeset:   0:23c3be426dce
  user:        test
  date:        Thu Jan 01 00:00:01 1970 +0000
  summary:     1: add c, move f to d
  
  $ hg cat -r tip a b
  a
  a
  a
  b
  b
  $ hg -q verify
  $ cd ..

Convert from merge

  $ hg convert --config convert.hg.startrev=4 source conv4
  initializing destination conv4 repository
  scanning source...
  sorting...
  converting...
  1 4: merge 2 and 3
  0 5: change a
  $ glog conv4
  o  1 "5: change a" files: a
  |
  o  0 "4: merge 2 and 3" files: a b c d e
  
  $ cd conv4
  $ hg up -C
  5 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg cat -r tip a b
  a
  a
  a
  b
  b
  $ hg -q verify
  $ cd ..

Convert from revset in convert.hg.revs

  $ hg convert --config convert.hg.revs='3:4+0' source revsetrepo
  initializing destination revsetrepo repository
  scanning source...
  sorting...
  converting...
  2 0: add a b f
  1 3: change a
  0 4: merge 2 and 3

  $ glog revsetrepo
  o  2 "4: merge 2 and 3" files: b c d e f
  |
  o  1 "3: change a" files: a
  |
  o  0 "0: add a b f" files: a b f
  
Convert from specified revs

  $ hg convert --rev 3 --rev 2 source multiplerevs
  initializing destination multiplerevs repository
  scanning source...
  sorting...
  converting...
  3 0: add a b f
  2 1: add c, move f to d
  1 2: copy e from a, change b
  0 3: change a
  $ glog multiplerevs
  o  3 "3: change a" files: a
  |
  | o  2 "2: copy e from a, change b" files: b e
  | |
  | o  1 "1: add c, move f to d" files: c d f
  |/
  o  0 "0: add a b f" files: a b f
  
Convert in multiple steps that doesn't overlap - the link to the parent is
preserved anyway

  $ hg convert --config convert.hg.revs=::1 source multistep
  initializing destination multistep repository
  scanning source...
  sorting...
  converting...
  1 0: add a b f
  0 1: add c, move f to d
  $ hg convert --config convert.hg.revs=2 source multistep
  scanning source...
  sorting...
  converting...
  0 2: copy e from a, change b
  $ glog multistep
  o  2 "2: copy e from a, change b" files: b e
  |
  o  1 "1: add c, move f to d" files: c d f
  |
  o  0 "0: add a b f" files: a b f