nuageinit: fix TOCTOU in addsshkey, adddoas, addsudo
Replace check-then-create patterns with direct creation: - addsshkey: check what exists before creation, use mkdir_p() for .ssh directory, handle errors with warnmsg() instead of assert(). Apply chmod/chown only on newly created files/directories. - adddoas: same pattern for doas.conf and the etc directory. - addsudo: same pattern for the sudoers file and sudoers.d directory. All three functions now use warnmsg() for error handling instead of returning nil,err or using assert().
This commit is contained in:
Baptiste Daroussin
+52
-40
@@ -349,25 +349,33 @@ local function addgroup(grp)
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end
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local function addsshkey(homedir, key)
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local chownak = false
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local chowndotssh = false
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local root = os.getenv("NUAGE_FAKE_ROOTDIR")
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if root then
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homedir = root .. "/" .. homedir
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end
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local ak_path = homedir .. "/.ssh/authorized_keys"
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local dotssh_path = homedir .. "/.ssh"
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local dirattrs = lfs.attributes(ak_path)
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if dirattrs == nil then
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chownak = true
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dirattrs = lfs.attributes(dotssh_path)
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if dirattrs == nil then
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assert(lfs.mkdir(dotssh_path))
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chowndotssh = true
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dirattrs = lfs.attributes(homedir)
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-- Check what already exists before creating anything
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local ak_exists = lfs.attributes(ak_path) ~= nil
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local dotssh_exists = lfs.attributes(dotssh_path) ~= nil
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-- Ensure .ssh directory exists
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if not dotssh_exists then
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local r, err = mkdir_p(dotssh_path)
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if not r then
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warnmsg("cannot create " .. dotssh_path .. ": " .. err)
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return
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end
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end
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-- Get homedir attributes for ownership
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local dirattrs = lfs.attributes(homedir)
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if not dirattrs then
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warnmsg("cannot get attributes for " .. homedir)
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return
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end
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local f = io.open(ak_path, "a")
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if not f then
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warnmsg("impossible to open " .. ak_path)
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@@ -375,19 +383,19 @@ local function addsshkey(homedir, key)
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end
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f:write(key .. "\n")
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f:close()
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if chownak then
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-- Set permissions and ownership on newly created files/dirs
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if not ak_exists then
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chmod(ak_path, "0600")
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chown(ak_path, dirattrs.uid, dirattrs.gid)
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end
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if chowndotssh then
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if not dotssh_exists then
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chmod(dotssh_path, "0700")
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chown(dotssh_path, dirattrs.uid, dirattrs.gid)
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end
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end
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local function adddoas(pwd)
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local chmodetcdir = false
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local chmoddoasconf = false
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local root = os.getenv("NUAGE_FAKE_ROOTDIR")
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local localbase = getlocalbase()
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local etcdir = localbase .. "/etc"
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@@ -395,18 +403,19 @@ local function adddoas(pwd)
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etcdir= root .. etcdir
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end
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local doasconf = etcdir .. "/doas.conf"
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local doasconf_attr = lfs.attributes(doasconf)
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if doasconf_attr == nil then
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chmoddoasconf = true
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local dirattrs = lfs.attributes(etcdir)
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if dirattrs == nil then
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local r, err = mkdir_p(etcdir)
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if not r then
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return nil, err .. " (creating " .. etcdir .. ")"
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end
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chmodetcdir = true
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local doasconf_exists = lfs.attributes(doasconf) ~= nil
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local etcdir_exists = lfs.attributes(etcdir) ~= nil
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-- Ensure etc directory exists
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if not etcdir_exists then
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local r, err = mkdir_p(etcdir)
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if not r then
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warnmsg("cannot create " .. etcdir .. ": " .. err)
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return
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end
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end
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local f = io.open(doasconf, "a")
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if not f then
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warnmsg("impossible to open " .. doasconf)
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@@ -424,17 +433,17 @@ local function adddoas(pwd)
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end
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end
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f:close()
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if chmoddoasconf then
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-- Set permissions on newly created files/dirs
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if not doasconf_exists then
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chmod(doasconf, "0640")
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end
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if chmodetcdir then
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if not etcdir_exists then
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chmod(etcdir, "0755")
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end
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end
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local function addsudo(pwd)
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local chmodsudoersd = false
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local chmodsudoers = false
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local root = os.getenv("NUAGE_FAKE_ROOTDIR")
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local localbase = getlocalbase()
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local sudoers_dir = localbase .. "/etc/sudoers.d"
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@@ -442,18 +451,19 @@ local function addsudo(pwd)
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sudoers_dir= root .. sudoers_dir
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end
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local sudoers = sudoers_dir .. "/90-nuageinit-users"
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local sudoers_attr = lfs.attributes(sudoers)
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if sudoers_attr == nil then
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chmodsudoers = true
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local dirattrs = lfs.attributes(sudoers_dir)
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if dirattrs == nil then
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local r, err = mkdir_p(sudoers_dir)
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if not r then
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return nil, err .. " (creating " .. sudoers_dir .. ")"
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end
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chmodsudoersd = true
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local sudoers_exists = lfs.attributes(sudoers) ~= nil
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local sudoers_dir_exists = lfs.attributes(sudoers_dir) ~= nil
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-- Ensure sudoers.d directory exists
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if not sudoers_dir_exists then
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local r, err = mkdir_p(sudoers_dir)
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if not r then
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warnmsg("cannot create " .. sudoers_dir .. ": " .. err)
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return
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end
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end
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local f = io.open(sudoers, "a")
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if not f then
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warnmsg("impossible to open " .. sudoers)
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@@ -467,10 +477,12 @@ local function addsudo(pwd)
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end
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end
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f:close()
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if chmodsudoers then
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-- Set permissions on newly created files/dirs
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if not sudoers_exists then
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chmod(sudoers, "0440")
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end
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if chmodsudoersd then
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if not sudoers_dir_exists then
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chmod(sudoers_dir, "0750")
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end
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end
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