Print error if chdir, setgroups, setuid, or setgid failed

4 files changed, 100 insertions, 66 deletions

diff --git a/src/common.nim b/src/common.nim
index c42cb82..2b9651a 100644
--- a/src/common.nim
+++ b/src/common.nim
@@ -236,22 +236,29 @@ proc bisectVersion(repoPath: string, debug: bool, firstCommit: Option[string],
         discard close(1)
         discard close(2)
 
-      dropPrivileges()
-      execResult(args)))
+      if dropPrivileges():
+        execResult(args)
+      else:
+        quit(1)))
 
   let (workFirstCommit, checkFirst) = if firstCommit.isSome:
       (firstCommit, false)
     else:
       (forkWaitRedirect(() => (block:
-        dropPrivileges()
-        execResult(gitCmd, "-C", repoPath,
-          "rev-list", "--max-parents=0", "@")))
+        if dropPrivileges():
+          execResult(gitCmd, "-C", repoPath,
+            "rev-list", "--max-parents=0", "@")
+        else:
+          quit(1)))
         .output.optLast, true)
 
   let (realLastThreeCommits, _) = forkWaitRedirect(() => (block:
-    dropPrivileges()
-    execResult(gitCmd, "-C", repoPath,
-      "rev-list", "--max-count=3", "@")))
+    if dropPrivileges():
+      execResult(gitCmd, "-C", repoPath,
+        "rev-list", "--max-count=3", "@")
+    else:
+      quit(1)))
+
   let index = workFirstCommit.map(c => realLastThreeCommits.find(c)).get(-1)
   let lastThreeCommits = if index >= 0:
       realLastThreeCommits[0 .. index]
@@ -266,9 +273,11 @@ proc bisectVersion(repoPath: string, debug: bool, firstCommit: Option[string],
       none(string)
     else:
       let foundVersion = forkWaitRedirect(() => (block:
-        dropPrivileges()
-        execResult(pkgLibDir & "/bisect",
-          compareMethod, repoPath & "/" & gitSubdir, version)))
+        if dropPrivileges():
+          execResult(pkgLibDir & "/bisect",
+            compareMethod, repoPath & "/" & gitSubdir, version)
+        else:
+          quit(1)))
         .output.optFirst
 
       let checkout2Code = forkExecWithoutOutput(gitCmd, "-C", repoPath,
@@ -308,9 +317,11 @@ proc bisectVersion(repoPath: string, debug: bool, firstCommit: Option[string],
         "bisect", "run", pkgLibDir & "/bisect", compareMethod, gitSubdir, version)
 
       let commit = forkWaitRedirect(() => (block:
-        dropPrivileges()
-        execResult(gitCmd, "-C", repoPath,
-          "rev-list", "--max-count=1", "refs/bisect/bad")))
+        if dropPrivileges():
+          execResult(gitCmd, "-C", repoPath,
+            "rev-list", "--max-count=1", "refs/bisect/bad")
+        else:
+          quit(1)))
         .output.optFirst
 
       discard forkExecWithoutOutput(gitCmd, "-C", repoPath,
@@ -330,9 +341,10 @@ proc bisectVersion(repoPath: string, debug: bool, firstCommit: Option[string],
 
 proc obtainSrcInfo*(path: string): string =
   let (output, code) = forkWaitRedirect(() => (block:
-    discard chdir(path)
-    dropPrivileges()
-    execResult(makePkgCmd, "--printsrcinfo")))
+    if dropPrivileges() and chdir(path) == 0:
+      execResult(makePkgCmd, "--printsrcinfo")
+    else:
+      quit(1)))
 
   if code == 0:
     output.foldl(a & b & "\n", "")
@@ -368,10 +380,12 @@ proc obtainBuildPkgInfosInternal(config: Config, bases: seq[LookupBaseGroup],
         removeDirQuiet(repoPath)
 
         if forkWait(() => (block:
-          dropPrivileges()
-          execResult(gitCmd, "-C", config.tmpRoot,
-            "clone", "-q", git.url, "-b", git.branch,
-            "--single-branch", base))) == 0:
+          if dropPrivileges():
+            execResult(gitCmd, "-C", config.tmpRoot,
+              "clone", "-q", git.url, "-b", git.branch,
+              "--single-branch", base)
+          else:
+            quit(1))) == 0:
           let commit = bisectVersion(repoPath, config.debug, none(string),
             "source", git.path, version)
 
@@ -380,9 +394,11 @@ proc obtainBuildPkgInfosInternal(config: Config, bases: seq[LookupBaseGroup],
             (newSeq[PackageInfo](), none(string))
           else:
             discard forkWait(() => (block:
-              dropPrivileges()
-              execResult(gitCmd, "-C", repoPath,
-                "checkout", "-q", commit.unsafeGet)))
+              if dropPrivileges():
+                execResult(gitCmd, "-C", repoPath,
+                  "checkout", "-q", commit.unsafeGet)
+              else:
+                quit(1)))
 
             let srcInfo = obtainSrcInfo(repoPath & "/" & git.path)
             let pkgInfos = parseSrcInfo(repo, srcInfo, config.arch,
@@ -439,8 +455,10 @@ proc cloneAurRepo*(config: Config, basePackages: seq[PackageInfo]): (int, Option
     raise newException(SystemError, "invalid clone call")
   else:
     let cloneCode = forkWait(() => (block:
-      dropPrivileges()
-      execResult(gitCmd, "-C", config.tmpRoot,
-        "clone", "-q", basePackages[0].gitUrl, "--single-branch", base)))
+      if dropPrivileges():
+        execResult(gitCmd, "-C", config.tmpRoot,
+          "clone", "-q", basePackages[0].gitUrl, "--single-branch", base)
+      else:
+        quit(1)))
 
     (cloneCode, none(string))
diff --git a/src/feature/syncinstall.nim b/src/feature/syncinstall.nim
index 94bb886..4fa5eaa 100644
--- a/src/feature/syncinstall.nim
+++ b/src/feature/syncinstall.nim
@@ -240,6 +240,17 @@ proc printUnsatisfied(config: Config,
               trp("unable to satisfy dependency '%s' required by %s\n") %
               [$reference, pkgInfo.name])
 
+template dropPrivilegesAndChdir(path: Option[string], body: untyped): int =
+  if dropPrivileges():
+    if path.isNone or chdir(path.unsafeGet) == 0:
+      body
+    else:
+      printError(config.color, tr"chdir failed: $#" % [path.unsafeGet])
+      quit(1)
+  else:
+    printError(config.color, tr"failed to drop privileges")
+    quit(1)
+
 proc editLoop(config: Config, base: string, repoPath: string, gitSubdir: Option[string],
   defaultYes: bool, noconfirm: bool): char =
   proc editFileLoop(file: string): char =
@@ -266,25 +277,25 @@ proc editLoop(config: Config, base: string, repoPath: string, gitSubdir: Option[
       if editor.strip.len == 0:
         'n'
       else:
-        discard forkWait(proc: int =
-          discard chdir(buildPath(repoPath, gitSubdir))
-          dropPrivileges()
-          execResult(bashCmd, "-c", """$1 "$2"""", "bash", editor, file))
+        discard forkWait(() => (block:
+          let buildPath = buildPath(repoPath, gitSubdir)
+          dropPrivilegesAndChdir(some(buildPath)):
+            execResult(bashCmd, "-c", """$1 "$2"""", "bash", editor, file)))
         editFileLoop(file)
     else:
       res
 
   let rawFiles = if gitSubdir.isSome:
       forkWaitRedirect(() => (block:
-        dropPrivileges()
-        execResult(gitCmd, "-C", repoPath, "ls-tree", "-r", "--name-only", "@",
-          gitSubdir.unsafeGet & "/")))
+        dropPrivilegesAndChdir(none(string)):
+          execResult(gitCmd, "-C", repoPath, "ls-tree", "-r", "--name-only", "@",
+            gitSubdir.unsafeGet & "/")))
         .output
         .map(s => s[gitSubdir.unsafeGet.len + 1 .. ^1])
     else:
       forkWaitRedirect(() => (block:
-        dropPrivileges()
-        execResult(gitCmd, "-C", repoPath, "ls-tree", "-r", "--name-only", "@")))
+        dropPrivilegesAndChdir(none(string)):
+          execResult(gitCmd, "-C", repoPath, "ls-tree", "-r", "--name-only", "@")))
         .output
 
   let files = ("PKGBUILD" & rawFiles.filter(x => x != ".SRCINFO")).deduplicate
@@ -338,20 +349,18 @@ proc buildLoop(config: Config, pkgInfos: seq[PackageInfo], noconfirm: bool,
     let envExt = getEnv("PKGEXT")
     let confExt = if envExt.len == 0:
         forkWaitRedirect(() => (block:
-          dropPrivileges()
-          execResult(bashCmd, "-c",
-            "source \"$@\" && echo \"$PKGEXT\"",
-            "bash", workConfFile)))
+          dropPrivilegesAndChdir(none(string)):
+            execResult(bashCmd, "-c",
+              "source \"$@\" && echo \"$PKGEXT\"",
+              "bash", workConfFile)))
           .output.optFirst.get("")
       else:
         envExt
 
     let (buildCode, interrupted) = catchInterrupt():
       forkWait(proc: int =
-        if chdir(buildPath) == 0:
-          discard cunsetenv("MAKEPKG_CONF")
-          dropPrivileges()
-
+        discard cunsetenv("MAKEPKG_CONF")
+        dropPrivilegesAndChdir(some(buildPath)):
           if not noextract:
             removeDirQuiet(buildPath & "src")
 
@@ -361,9 +370,7 @@ proc buildLoop(config: Config, pkgInfos: seq[PackageInfo], noconfirm: bool,
           ]
 
           execResult(@[makepkgCmd, "--config", workConfFile, "-f"] &
-            optional.filter(o => o.cond).map(o => o.arg))
-        else:
-          quit(1))
+            optional.filter(o => o.cond).map(o => o.arg)))
 
     discard unlink(workConfFile)
 
@@ -450,9 +457,8 @@ proc buildFromSources(config: Config, commonArgs: seq[Argument],
       printColon(config.color, tr"Running pre-build command...")
 
       let code = forkWait(() => (block:
-        discard chdir(buildPath(repoPath, gitSubdir))
-        dropPrivileges()
-        execResult(bashCmd, "-c", config.preBuildCommand.unsafeGet)))
+        dropPrivilegesAndChdir(some(buildPath(repoPath, gitSubdir))):
+          execResult(bashCmd, "-c", config.preBuildCommand.unsafeGet)))
 
       if code != 0 and printColonUserChoice(config.color,
         tr"Command failed, continue?", ['y', 'n'], 'n', 'n',
@@ -665,8 +671,8 @@ proc handleInstall(args: seq[Argument], config: Config, upgradeCount: int,
                       discard open("/dev/null")
                       discard close(2)
                       discard open("/dev/null")
-                      dropPrivileges()
-                      execResult(gpgCmd, "--list-keys", pgpKeys[index]))) == 0:
+                      dropPrivilegesAndChdir(none(string)):
+                        execResult(gpgCmd, "--list-keys", pgpKeys[index]))) == 0:
                       keysLoop(index + 1, skipKeys)
                     else:
                       let res = if skipKeys:
@@ -684,14 +690,14 @@ proc handleInstall(args: seq[Argument], config: Config, upgradeCount: int,
                         keysLoop(index, newSkipKeys)
                       elif res == 'y' or newSkipKeys:
                         let importCode = forkWait(() => (block:
-                          dropPrivileges()
-                          if config.pgpKeyserver.isSome:
-                            forkWait(() => execResult(gpgCmd,
-                              "--keyserver", config.pgpKeyserver.unsafeGet,
-                              "--recv-keys", pgpKeys[index]))
-                          else:
-                            forkWait(() => execResult(gpgCmd,
-                              "--recv-keys", pgpKeys[index]))))
+                          dropPrivilegesAndChdir(none(string)):
+                            if config.pgpKeyserver.isSome:
+                              forkWait(() => execResult(gpgCmd,
+                                "--keyserver", config.pgpKeyserver.unsafeGet,
+                                "--recv-keys", pgpKeys[index]))
+                            else:
+                              forkWait(() => execResult(gpgCmd,
+                                "--recv-keys", pgpKeys[index]))))
 
                         if importCode == 0 or newSkipKeys or noconfirm:
                           keysLoop(index + 1, newSkipKeys)
diff --git a/src/pacman.nim b/src/pacman.nim
index 05abf51..58bf42b 100644
--- a/src/pacman.nim
+++ b/src/pacman.nim
@@ -356,8 +356,10 @@ proc obtainPacmanConfig*(args: seq[Argument]): PacmanConfig =
     x <- y.split(',')), string].toSet
 
   let hasKeyserver = forkWaitRedirect(() => (block:
-    dropPrivileges()
-    execResult(gpgConfCmd, "--list-options", "gpg")))
+    if dropPrivileges():
+      execResult(gpgConfCmd, "--list-options", "gpg")
+    else:
+      quit(1)))
     .output
     .filter(s => s.len > 10 and s[0 .. 9] == "keyserver:" and not (s[^2] == ':'))
     .len > 0
diff --git a/src/utils.nim b/src/utils.nim
index 7cbf184..b480ce9 100644
--- a/src/utils.nim
+++ b/src/utils.nim
@@ -253,13 +253,17 @@ except:
 proc canDropPrivileges*(): bool =
   initialUser.isSome
 
-proc dropPrivileges*() =
+proc dropPrivileges*(): bool =
   if initialUser.isSome:
     let user = initialUser.unsafeGet
     var groups = user.groups.map(x => x.cint)
-    discard setgroups(user.groups.len, addr(groups[0]));
-    discard setgid((Gid) user.gid)
-    discard setuid((Uid) user.uid)
+
+    if setgroups(user.groups.len, addr(groups[0])) < 0:
+      return false
+    if setgid((Gid) user.gid) != 0:
+      return false
+    if setuid((Uid) user.uid) != 0:
+      return false
 
     template replaceExisting(name: string, value: string) =
       if cgetenv(name) != nil:
@@ -277,6 +281,10 @@ proc dropPrivileges*() =
     discard cunsetenv("SUDO_GID")
     discard cunsetenv("PKEXEC_UID")
 
+    return true
+  else:
+    return true
+
 var intSigact: SigAction
 intSigact.sa_handler = SIG_DFL
 discard sigaction(SIGINT, intSigact)