git-compat-util: avoid failing dir ownership checks if running privileged

bdc77d1d685 (Add a function to determine whether a path is owned by the
current user, 2022-03-02) checks for the effective uid of the running
process using geteuid() but didn't account for cases where that user was
root (because git was invoked through sudo or a compatible tool) and the
original uid that repository trusted for its config was no longer known,
therefore failing the following otherwise safe call:

  guy@renard ~/Software/uncrustify $ sudo git describe --always --dirty
  [sudo] password for guy:
  fatal: unsafe repository ('/home/guy/Software/uncrustify' is owned by someone else)

Attempt to detect those cases by using the environment variables that
those tools create to keep track of the original user id, and do the
ownership check using that instead.

This assumes the environment the user is running on after going
privileged can't be tampered with, and also adds code to restrict that
the new behavior only applies if running as root, therefore keeping the
most common case, which runs unprivileged, from changing, but because of
that, it will miss cases where sudo (or an equivalent) was used to change
to another unprivileged user or where the equivalent tool used to raise
privileges didn't track the original id in a sudo compatible way.

Because of compatibility with sudo, the code assumes that uid_t is an
unsigned integer type (which is not required by the standard) but is used
that way in their codebase to generate SUDO_UID.  In systems where uid_t
is signed, sudo might be also patched to NOT be unsigned and that might
be able to trigger an edge case and a bug (as described in the code), but
it is considered unlikely to happen and even if it does, the code would
just mostly fail safely, so there was no attempt either to detect it or
prevent it by the code, which is something that might change in the future,
based on expected user feedback.

Reported-by: Guy Maurel <guy.j@maurel.de>
Helped-by: SZEDER Gábor <szeder.dev@gmail.com>
Helped-by: Randall Becker <rsbecker@nexbridge.com>
Helped-by: Phillip Wood <phillip.wood123@gmail.com>
Suggested-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
3 files changed
tree: 6c9397e6d261cd4c96e51d596a2afb75f03d5ea3
  1. .github/
  2. block-sha1/
  3. builtin/
  4. ci/
  5. compat/
  6. contrib/
  7. Documentation/
  8. ewah/
  9. git-gui/
  10. gitk-git/
  11. gitweb/
  12. mergetools/
  13. negotiator/
  14. perl/
  15. po/
  16. ppc/
  17. refs/
  18. sha1dc/
  19. sha256/
  20. t/
  21. templates/
  22. trace2/
  23. vcs-svn/
  24. xdiff/
  25. .cirrus.yml
  26. .clang-format
  27. .editorconfig
  28. .gitattributes
  29. .gitignore
  30. .gitmodules
  31. .mailmap
  32. .travis.yml
  33. .tsan-suppressions
  34. abspath.c
  35. aclocal.m4
  36. add-interactive.c
  37. add-interactive.h
  38. add-patch.c
  39. advice.c
  40. advice.h
  41. alias.c
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  43. alloc.c
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  45. apply.c
  46. apply.h
  47. archive-tar.c
  48. archive-zip.c
  49. archive.c
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  51. attr.c
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  53. banned.h
  54. base85.c
  55. bisect.c
  56. bisect.h
  57. blame.c
  58. blame.h
  59. blob.c
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  61. bloom.c
  62. bloom.h
  63. branch.c
  64. branch.h
  65. builtin.h
  66. bulk-checkin.c
  67. bulk-checkin.h
  68. bundle.c
  69. bundle.h
  70. cache-tree.c
  71. cache-tree.h
  72. cache.h
  73. chdir-notify.c
  74. chdir-notify.h
  75. check-builtins.sh
  76. check_bindir
  77. checkout.c
  78. checkout.h
  79. CODE_OF_CONDUCT.md
  80. color.c
  81. color.h
  82. column.c
  83. column.h
  84. combine-diff.c
  85. command-list.txt
  86. commit-graph.c
  87. commit-graph.h
  88. commit-reach.c
  89. commit-reach.h
  90. commit-slab-decl.h
  91. commit-slab-impl.h
  92. commit-slab.h
  93. commit.c
  94. commit.h
  95. common-main.c
  96. config.c
  97. config.h
  98. config.mak.dev
  99. config.mak.in
  100. config.mak.uname
  101. configure.ac
  102. connect.c
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  106. convert.c
  107. convert.h
  108. copy.c
  109. COPYING
  110. credential.c
  111. credential.h
  112. csum-file.c
  113. csum-file.h
  114. ctype.c
  115. daemon.c
  116. date.c
  117. decorate.c
  118. decorate.h
  119. delta-islands.c
  120. delta-islands.h
  121. delta.h
  122. detect-compiler
  123. diff-delta.c
  124. diff-lib.c
  125. diff-no-index.c
  126. diff.c
  127. diff.h
  128. diffcore-break.c
  129. diffcore-delta.c
  130. diffcore-order.c
  131. diffcore-pickaxe.c
  132. diffcore-rename.c
  133. diffcore.h
  134. dir-iterator.c
  135. dir-iterator.h
  136. dir.c
  137. dir.h
  138. editor.c
  139. entry.c
  140. environment.c
  141. exec-cmd.c
  142. exec-cmd.h
  143. fetch-negotiator.c
  144. fetch-negotiator.h
  145. fetch-pack.c
  146. fetch-pack.h
  147. fmt-merge-msg.c
  148. fmt-merge-msg.h
  149. fsck.c
  150. fsck.h
  151. fsmonitor.c
  152. fsmonitor.h
  153. fuzz-commit-graph.c
  154. fuzz-pack-headers.c
  155. fuzz-pack-idx.c
  156. generate-cmdlist.sh
  157. generate-configlist.sh
  158. gettext.c
  159. gettext.h
  160. git-add--interactive.perl
  161. git-archimport.perl
  162. git-bisect.sh
  163. git-compat-util.h
  164. git-cvsexportcommit.perl
  165. git-cvsimport.perl
  166. git-cvsserver.perl
  167. git-difftool--helper.sh
  168. git-filter-branch.sh
  169. git-instaweb.sh
  170. git-merge-octopus.sh
  171. git-merge-one-file.sh
  172. git-merge-resolve.sh
  173. git-mergetool--lib.sh
  174. git-mergetool.sh
  175. git-p4.py
  176. git-quiltimport.sh
  177. git-rebase--preserve-merges.sh
  178. git-request-pull.sh
  179. git-send-email.perl
  180. git-sh-i18n.sh
  181. git-sh-setup.sh
  182. git-submodule.sh
  183. git-svn.perl
  184. GIT-VERSION-GEN
  185. git-web--browse.sh
  186. git.c
  187. git.rc
  188. gpg-interface.c
  189. gpg-interface.h
  190. graph.c
  191. graph.h
  192. grep.c
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  194. hash.h
  195. hashmap.c
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  197. help.c
  198. help.h
  199. hex.c
  200. http-backend.c
  201. http-fetch.c
  202. http-push.c
  203. http-walker.c
  204. http.c
  205. http.h
  206. ident.c
  207. imap-send.c
  208. INSTALL
  209. iterator.h
  210. json-writer.c
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  212. khash.h
  213. kwset.c
  214. kwset.h
  215. levenshtein.c
  216. levenshtein.h
  217. LGPL-2.1
  218. line-log.c
  219. line-log.h
  220. line-range.c
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  222. linear-assignment.c
  223. linear-assignment.h
  224. list-objects-filter-options.c
  225. list-objects-filter-options.h
  226. list-objects-filter.c
  227. list-objects-filter.h
  228. list-objects.c
  229. list-objects.h
  230. list.h
  231. ll-merge.c
  232. ll-merge.h
  233. lockfile.c
  234. lockfile.h
  235. log-tree.c
  236. log-tree.h
  237. ls-refs.c
  238. ls-refs.h
  239. mailinfo.c
  240. mailinfo.h
  241. mailmap.c
  242. mailmap.h
  243. Makefile
  244. match-trees.c
  245. mem-pool.c
  246. mem-pool.h
  247. merge-blobs.c
  248. merge-blobs.h
  249. merge-ort-wrappers.c
  250. merge-ort-wrappers.h
  251. merge-ort.c
  252. merge-ort.h
  253. merge-recursive.c
  254. merge-recursive.h
  255. merge.c
  256. mergesort.c
  257. mergesort.h
  258. midx.c
  259. midx.h
  260. name-hash.c
  261. notes-cache.c
  262. notes-cache.h
  263. notes-merge.c
  264. notes-merge.h
  265. notes-utils.c
  266. notes-utils.h
  267. notes.c
  268. notes.h
  269. object-store.h
  270. object.c
  271. object.h
  272. oid-array.c
  273. oid-array.h
  274. oidmap.c
  275. oidmap.h
  276. oidset.c
  277. oidset.h
  278. pack-bitmap-write.c
  279. pack-bitmap.c
  280. pack-bitmap.h
  281. pack-check.c
  282. pack-objects.c
  283. pack-objects.h
  284. pack-revindex.c
  285. pack-revindex.h
  286. pack-write.c
  287. pack.h
  288. packfile.c
  289. packfile.h
  290. pager.c
  291. parse-options-cb.c
  292. parse-options.c
  293. parse-options.h
  294. patch-delta.c
  295. patch-ids.c
  296. patch-ids.h
  297. path.c
  298. path.h
  299. pathspec.c
  300. pathspec.h
  301. pkt-line.c
  302. pkt-line.h
  303. preload-index.c
  304. pretty.c
  305. pretty.h
  306. prio-queue.c
  307. prio-queue.h
  308. progress.c
  309. progress.h
  310. promisor-remote.c
  311. promisor-remote.h
  312. prompt.c
  313. prompt.h
  314. protocol.c
  315. protocol.h
  316. prune-packed.c
  317. prune-packed.h
  318. quote.c
  319. quote.h
  320. range-diff.c
  321. range-diff.h
  322. reachable.c
  323. reachable.h
  324. read-cache.c
  325. README.md
  326. rebase-interactive.c
  327. rebase-interactive.h
  328. rebase.c
  329. rebase.h
  330. ref-filter.c
  331. ref-filter.h
  332. reflog-walk.c
  333. reflog-walk.h
  334. refs.c
  335. refs.h
  336. refspec.c
  337. refspec.h
  338. remote-curl.c
  339. remote.c
  340. remote.h
  341. replace-object.c
  342. replace-object.h
  343. repo-settings.c
  344. repository.c
  345. repository.h
  346. rerere.c
  347. rerere.h
  348. reset.c
  349. reset.h
  350. resolve-undo.c
  351. resolve-undo.h
  352. revision.c
  353. revision.h
  354. run-command.c
  355. run-command.h
  356. send-pack.c
  357. send-pack.h
  358. sequencer.c
  359. sequencer.h
  360. serve.c
  361. serve.h
  362. server-info.c
  363. setup.c
  364. sh-i18n--envsubst.c
  365. sha1-file.c
  366. sha1-lookup.c
  367. sha1-lookup.h
  368. sha1-name.c
  369. sha1dc_git.c
  370. sha1dc_git.h
  371. shallow.c
  372. shallow.h
  373. shell.c
  374. shortlog.h
  375. sideband.c
  376. sideband.h
  377. sigchain.c
  378. sigchain.h
  379. split-index.c
  380. split-index.h
  381. stable-qsort.c
  382. strbuf.c
  383. strbuf.h
  384. streaming.c
  385. streaming.h
  386. string-list.c
  387. string-list.h
  388. strmap.c
  389. strmap.h
  390. strvec.c
  391. strvec.h
  392. sub-process.c
  393. sub-process.h
  394. submodule-config.c
  395. submodule-config.h
  396. submodule.c
  397. submodule.h
  398. symlinks.c
  399. tag.c
  400. tag.h
  401. tar.h
  402. tempfile.c
  403. tempfile.h
  404. thread-utils.c
  405. thread-utils.h
  406. tmp-objdir.c
  407. tmp-objdir.h
  408. trace.c
  409. trace.h
  410. trace2.c
  411. trace2.h
  412. trailer.c
  413. trailer.h
  414. transport-helper.c
  415. transport-internal.h
  416. transport.c
  417. transport.h
  418. tree-diff.c
  419. tree-walk.c
  420. tree-walk.h
  421. tree.c
  422. tree.h
  423. unicode-width.h
  424. unimplemented.sh
  425. unix-socket.c
  426. unix-socket.h
  427. unpack-trees.c
  428. unpack-trees.h
  429. upload-pack.c
  430. upload-pack.h
  431. url.c
  432. url.h
  433. urlmatch.c
  434. urlmatch.h
  435. usage.c
  436. userdiff.c
  437. userdiff.h
  438. utf8.c
  439. utf8.h
  440. varint.c
  441. varint.h
  442. version.c
  443. version.h
  444. versioncmp.c
  445. walker.c
  446. walker.h
  447. wildmatch.c
  448. wildmatch.h
  449. worktree.c
  450. worktree.h
  451. wrap-for-bin.sh
  452. wrapper.c
  453. write-or-die.c
  454. ws.c
  455. wt-status.c
  456. wt-status.h
  457. xdiff-interface.c
  458. xdiff-interface.h
  459. zlib.c
README.md

Build status

Git - fast, scalable, distributed revision control system

Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.

Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.

Please read the file INSTALL for installation instructions.

Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.

See Documentation/gittutorial.txt to get started, then see Documentation/giteveryday.txt for a useful minimum set of commands, and Documentation/git-<commandname>.txt for documentation of each command. If git has been correctly installed, then the tutorial can also be read with man gittutorial or git help tutorial, and the documentation of each command with man git-<commandname> or git help <commandname>.

CVS users may also want to read Documentation/gitcvs-migration.txt (man gitcvs-migration or git help cvs-migration if git is installed).

The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission). To subscribe to the list, send an email with just “subscribe git” in the body to majordomo@vger.kernel.org. The mailing list archives are available at https://lore.kernel.org/git/, http://marc.info/?l=git and other archival sites.

Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.

The maintainer frequently sends the “What's cooking” reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.

The name “git” was given by Linus Torvalds when he wrote the very first version. He described the tool as “the stupid content tracker” and the name as (depending on your mood):

  • random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of “get” may or may not be relevant.
  • stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
  • “global information tracker”: you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
  • “goddamn idiotic truckload of sh*t”: when it breaks