diff options
| -rw-r--r-- | doc/guix.texi | 34 | ||||
| -rw-r--r-- | guix/scripts/environment.scm | 122 | ||||
| -rw-r--r-- | tests/guix-environment-container.sh | 11 |
3 files changed, 138 insertions, 29 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index 826f924d22..d35ce0e26b 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -7286,10 +7286,11 @@ Attempt to build for @var{system}---e.g., @code{i686-linux}. @cindex container Run @var{command} within an isolated container. The current working directory outside the container is mapped inside the container. -Additionally, a dummy home directory is created that matches the current -user's home directory, and @file{/etc/passwd} is configured accordingly. -The spawned process runs as the current user outside the container, but -has root privileges in the context of the container. +Additionally, unless overridden with @code{--user}, a dummy home +directory is created that matches the current user's home directory, and +@file{/etc/passwd} is configured accordingly. The spawned process runs +as the current user outside the container, but has root privileges in +the context of the container. @item --network @itemx -N @@ -7313,6 +7314,31 @@ example, the @code{fontconfig} package inspects @code{--link-profile} allows these programs to behave as expected within the environment. +@item --user=@var{user} +@itemx -u @var{user} +For containers, use the username @var{user} in place of the current +user. The generated @file{/etc/passwd} entry within the container will +contain the name @var{user}; the home directory will be +@file{/home/USER}; and no user GECOS data will be copied. @var{user} +need not exist on the system. + +Additionally, any shared or exposed path (see @code{--share} and +@code{--expose} respectively) whose target is within the current user's +home directory will be remapped relative to @file{/home/USER}; this +includes the automatic mapping of the current working directory. + +@example +# will expose paths as /home/foo/wd, /home/foo/test, and /home/foo/target +cd $HOME/wd +guix environment --container --user=foo \ + --expose=$HOME/test \ + --expose=/tmp/target=$HOME/target +@end example + +While this will limit the leaking of user identity through home paths +and each of the user fields, this is only one useful component of a +broader privacy/anonymity solution---not one in and of itself. + @item --expose=@var{source}[=@var{target}] For containers, expose the file system @var{source} from the host system as the read-only file system @var{target} within the container. If diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm index 5c7d83881c..4f88c513c0 100644 --- a/guix/scripts/environment.scm +++ b/guix/scripts/environment.scm @@ -164,6 +164,10 @@ COMMAND or an interactive shell in that environment.\n")) -P, --link-profile link environment profile to ~/.guix-profile within an isolated container")) (display (G_ " + -u, --user=USER instead of copying the name and home of the current + user into an isolated container, use the name USER + with home directory /home/USER")) + (display (G_ " --share=SPEC for containers, share writable host file system according to SPEC")) (display (G_ " @@ -250,6 +254,10 @@ COMMAND or an interactive shell in that environment.\n")) (option '(#\P "link-profile") #f #f (lambda (opt name arg result) (alist-cons 'link-profile? #t result))) + (option '(#\u "user") #t #f + (lambda (opt name arg result) + (alist-cons 'user arg + (alist-delete 'user result eq?)))) (option '("share") #t #f (lambda (opt name arg result) (alist-cons 'file-system-mapping @@ -410,43 +418,50 @@ environment variables are cleared before setting the new ones." (pid (match (waitpid pid) ((_ . status) status))))) -(define* (launch-environment/container #:key command bash user-mappings +(define* (launch-environment/container #:key command bash user user-mappings profile paths link-profile? network?) "Run COMMAND within a container that features the software in PROFILE. Environment variables are set according to PATHS, a list of native search paths. The global shell is BASH, a file name for a GNU Bash binary in the store. When NETWORK?, access to the host system network is permitted. USER-MAPPINGS, a list of file system mappings, contains the user-specified -host file systems to mount inside the container. LINK-PROFILE? creates a -symbolic link from ~/.guix-profile to the environment profile." +host file systems to mount inside the container. If USER is not #f, each +target of USER-MAPPINGS will be re-written relative to '/home/USER', and USER +will be used for the passwd entry. LINK-PROFILE? creates a symbolic link from +~/.guix-profile to the environment profile." (mlet %store-monad ((reqs (inputs->requisites (list (direct-store-path bash) profile)))) (return (let* ((cwd (getcwd)) - (passwd (getpwuid (getuid))) + (home (getenv "HOME")) + (passwd (mock-passwd (getpwuid (getuid)) + user + bash)) (home-dir (passwd:dir passwd)) ;; Bind-mount all requisite store items, user-specified mappings, ;; /bin/sh, the current working directory, and possibly networking ;; configuration files within the container. (mappings - (append user-mappings - ;; Current working directory. - (list (file-system-mapping - (source cwd) - (target cwd) - (writable? #t))) - ;; When in Rome, do as Nix build.cc does: Automagically - ;; map common network configuration files. - (if network? - %network-file-mappings - '()) - ;; Mappings for the union closure of all inputs. - (map (lambda (dir) - (file-system-mapping - (source dir) - (target dir) - (writable? #f))) - reqs))) + (override-user-mappings + user home + (append user-mappings + ;; Current working directory. + (list (file-system-mapping + (source cwd) + (target cwd) + (writable? #t))) + ;; When in Rome, do as Nix build.cc does: Automagically + ;; map common network configuration files. + (if network? + %network-file-mappings + '()) + ;; Mappings for the union closure of all inputs. + (map (lambda (dir) + (file-system-mapping + (source dir) + (target dir) + (writable? #f))) + reqs)))) (file-systems (append %container-file-systems (map file-system-mapping->bind-mount mappings)))) @@ -467,8 +482,7 @@ symbolic link from ~/.guix-profile to the environment profile." ;; The same variables as in Nix's 'build.cc'. '("TMPDIR" "TEMPDIR" "TMP" "TEMP")) - ;; Create a dummy home directory under the same name as on the - ;; host. + ;; Create a dummy home directory. (mkdir-p home-dir) (setenv "HOME" home-dir) @@ -495,7 +509,7 @@ symbolic link from ~/.guix-profile to the environment profile." ;; For convenience, start in the user's current working ;; directory rather than the root directory. - (chdir cwd) + (chdir (override-user-dir user home cwd)) (primitive-exit/status ;; A container's environment is already purified, so no need to @@ -505,6 +519,60 @@ symbolic link from ~/.guix-profile to the environment profile." (delq 'net %namespaces) ; share host network %namespaces))))))) +(define (mock-passwd passwd user-override shell) + "Generate mock information for '/etc/passwd'. If USER-OVERRIDE is not '#f', +it is expected to be a string representing the mock username; it will produce +a user of that name, with a home directory of '/home/USER-OVERRIDE', and no +GECOS field. If USER-OVERRIDE is '#f', data will be inherited from PASSWD. +In either case, the shadow password and UID/GID are cleared, since the user +runs as root within the container. SHELL will always be used in place of the +shell in PASSWD. + +The resulting vector is suitable for use with Guile's POSIX user procedures. + +See passwd(5) for more information each of the fields." + (if user-override + (vector + user-override + "x" "0" "0" ;; no shadow, user is now root + "" ;; no personal information + (user-override-home user-override) + shell) + (vector + (passwd:name passwd) + "x" "0" "0" ;; no shadow, user is now root + (passwd:gecos passwd) + (passwd:dir passwd) + shell))) + +(define (user-override-home user) + "Return home directory for override user USER." + (string-append "/home/" user)) + +(define (override-user-mappings user home mappings) + "If a username USER is provided, rewrite each HOME prefix in file system +mappings MAPPINGS to a home directory determined by 'override-user-dir'; +otherwise, return MAPPINGS." + (if (not user) + mappings + (map (lambda (mapping) + (let ((target (file-system-mapping-target mapping))) + (if (string-prefix? home target) + (file-system-mapping + (source (file-system-mapping-source mapping)) + (target (override-user-dir user home target)) + (writable? (file-system-mapping-writable? mapping))) + mapping))) + mappings))) + +(define (override-user-dir user home dir) + "If username USER is provided, overwrite string prefix HOME in DIR with a +directory determined by 'user-override-home'; otherwise, return DIR." + (if (and user (string-prefix? home dir)) + (string-append (user-override-home user) + (substring dir (string-length home))) + dir)) + (define (link-environment profile home-dir) "Create a symbolic link from HOME-DIR/.guix-profile to PROFILE." (let ((profile-dir (string-append home-dir "/.guix-profile"))) @@ -592,6 +660,7 @@ message if any test fails." (container? (assoc-ref opts 'container?)) (link-prof? (assoc-ref opts 'link-profile?)) (network? (assoc-ref opts 'network?)) + (user (assoc-ref opts 'user)) (bootstrap? (assoc-ref opts 'bootstrap?)) (system (assoc-ref opts 'system)) (command (or (assoc-ref opts 'exec) @@ -626,6 +695,8 @@ message if any test fails." (when (and (not container?) link-prof?) (leave (G_ "'--link-profile' cannot be used without '--container'~%"))) + (when (and (not container?) user) + (leave (G_ "'--user' cannot be used without '--container'~%"))) (with-store store (set-build-options-from-command-line store opts) @@ -673,6 +744,7 @@ message if any test fails." "/bin/sh")))) (launch-environment/container #:command command #:bash bash-binary + #:user user #:user-mappings mappings #:profile profile #:paths paths diff --git a/tests/guix-environment-container.sh b/tests/guix-environment-container.sh index df40ce03e0..a2da9a0773 100644 --- a/tests/guix-environment-container.sh +++ b/tests/guix-environment-container.sh @@ -109,6 +109,17 @@ rm $tmpdir/mounts -- guile -c "$linktest" ) +# Test that user can be mocked. +usertest='(exit (and (string=? (getenv "HOME") "/home/foognu") + (string=? (passwd:name (getpwuid 0)) "foognu") + (file-exists? "/home/foognu/umock")))' +touch "$tmpdir/umock" +HOME="$tmpdir" guix environment --bootstrap --container --user=foognu \ + --ad-hoc guile-bootstrap --pure \ + --share="$tmpdir/umock" \ + -- guile -c "$usertest" + + # Check the exit code. abnormal_exit_code=" |