lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <132e8423-adf5-3343-8a09-2d09719ff262@huawei.com> Date: Sat, 10 Sep 2022 23:59:58 +0300 From: "Konstantin Meskhidze (A)" <konstantin.meskhidze@...wei.com> To: Mickaël Salaün <mic@...ikod.net> CC: <willemdebruijn.kernel@...il.com>, <gnoack3000@...il.com>, <linux-security-module@...r.kernel.org>, <netdev@...r.kernel.org>, <netfilter-devel@...r.kernel.org>, <anton.sirazetdinov@...wei.com> Subject: Re: [PATCH v7 17/18] samples/landlock: add network demo 9/6/2022 11:10 AM, Mickaël Salaün пишет: > > On 29/08/2022 19:04, Konstantin Meskhidze wrote: >> This commit adds network demo. It's possible to allow a sandboxer to >> bind/connect to a list of particular ports restricting network >> actions to the rest of ports. >> >> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com> >> --- >> >> Changes since v6: >> * Removes network support if ABI < 3. >> >> Changes since v5: >> * Makes network ports sandboxing optional. >> * Fixes some logic errors. >> * Formats code with clang-format-14. >> >> Changes since v4: >> * Adds ENV_TCP_BIND_NAME "LL_TCP_BIND" and >> ENV_TCP_CONNECT_NAME "LL_TCP_CONNECT" variables >> to insert TCP ports. >> * Renames populate_ruleset() to populate_ruleset_fs(). >> * Adds populate_ruleset_net() and parse_port_num() helpers. >> * Refactors main() to support network sandboxing. >> >> --- >> samples/landlock/sandboxer.c | 123 +++++++++++++++++++++++++++++++---- >> 1 file changed, 112 insertions(+), 11 deletions(-) >> >> diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c >> index 771b6b10d519..7f88067534df 100644 >> --- a/samples/landlock/sandboxer.c >> +++ b/samples/landlock/sandboxer.c >> @@ -51,6 +51,8 @@ static inline int landlock_restrict_self(const int ruleset_fd, >> >> #define ENV_FS_RO_NAME "LL_FS_RO" >> #define ENV_FS_RW_NAME "LL_FS_RW" >> +#define ENV_TCP_BIND_NAME "LL_TCP_BIND" >> +#define ENV_TCP_CONNECT_NAME "LL_TCP_CONNECT" >> #define ENV_PATH_TOKEN ":" >> >> static int parse_path(char *env_path, const char ***const path_list) >> @@ -71,6 +73,20 @@ static int parse_path(char *env_path, const char ***const path_list) >> return num_paths; >> } >> >> +static int parse_port_num(char *env_port) >> +{ >> + int i, num_ports = 0; >> + >> + if (env_port) { >> + num_ports++; >> + for (i = 0; env_port[i]; i++) { >> + if (env_port[i] == ENV_PATH_TOKEN[0]) >> + num_ports++; >> + } >> + } >> + return num_ports; >> +} >> + >> /* clang-format off */ >> >> #define ACCESS_FILE ( \ >> @@ -81,8 +97,8 @@ static int parse_path(char *env_path, const char ***const path_list) >> >> /* clang-format on */ >> >> -static int populate_ruleset(const char *const env_var, const int ruleset_fd, >> - const __u64 allowed_access) >> +static int populate_ruleset_fs(const char *const env_var, const int ruleset_fd, >> + const __u64 allowed_access) >> { >> int num_paths, i, ret = 1; >> char *env_path_name; >> @@ -143,6 +159,48 @@ static int populate_ruleset(const char *const env_var, const int ruleset_fd, >> return ret; >> } >> >> +static int populate_ruleset_net(const char *const env_var, const int ruleset_fd, >> + const __u64 allowed_access) >> +{ >> + int num_ports, i, ret = 1; >> + char *env_port_name; >> + struct landlock_net_service_attr net_service = { >> + .allowed_access = 0, >> + .port = 0, >> + }; >> + >> + env_port_name = getenv(env_var); >> + if (!env_port_name) { >> + ret = 0; >> + goto out_free_name; >> + } >> + env_port_name = strdup(env_port_name); >> + unsetenv(env_var); >> + num_ports = parse_port_num(env_port_name); >> + >> + if (num_ports == 1 && (strtok(env_port_name, ENV_PATH_TOKEN) == NULL)) { >> + ret = 0; >> + goto out_free_name; >> + } >> + >> + for (i = 0; i < num_ports; i++) { >> + net_service.allowed_access = allowed_access; >> + net_service.port = atoi(strsep(&env_port_name, ENV_PATH_TOKEN)); >> + if (landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_SERVICE, >> + &net_service, 0)) { >> + fprintf(stderr, >> + "Failed to update the ruleset with port \"%d\": %s\n", >> + net_service.port, strerror(errno)); >> + goto out_free_name; >> + } >> + } >> + ret = 0; >> + >> +out_free_name: >> + free(env_port_name); >> + return ret; >> +} >> + >> /* clang-format off */ >> >> #define ACCESS_FS_ROUGHLY_READ ( \ >> @@ -171,32 +229,50 @@ int main(const int argc, char *const argv[], char *const *const envp) >> const char *cmd_path; >> char *const *cmd_argv; >> int ruleset_fd, abi; >> + char *env_port_name; >> __u64 access_fs_ro = ACCESS_FS_ROUGHLY_READ, >> - access_fs_rw = ACCESS_FS_ROUGHLY_READ | ACCESS_FS_ROUGHLY_WRITE; >> + access_fs_rw = ACCESS_FS_ROUGHLY_READ | ACCESS_FS_ROUGHLY_WRITE, >> + access_net_tcp = 0; >> struct landlock_ruleset_attr ruleset_attr = { >> .handled_access_fs = access_fs_rw, >> + .handled_access_net = access_net_tcp, > > Please follow the same logic as for handled_access_fs: by default > handles all accesses, then remove the ones that are not supported by the > kernel, then remove the ones that are not explicitly set by users (by > checking env_port_name). > So at the beginning there will be full network ruleset attribute supported: .handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP | LANDLOCK_ACCESS_NET_CONNECT_TCP; Correct? > >> }; >> >> if (argc < 2) { >> fprintf(stderr, >> - "usage: %s=\"...\" %s=\"...\" %s <cmd> [args]...\n\n", >> - ENV_FS_RO_NAME, ENV_FS_RW_NAME, argv[0]); >> + "usage: %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\"%s " >> + "<cmd> [args]...\n\n", >> + ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME, >> + ENV_TCP_CONNECT_NAME, argv[0]); >> fprintf(stderr, >> "Launch a command in a restricted environment.\n\n"); >> - fprintf(stderr, "Environment variables containing paths, " >> - "each separated by a colon:\n"); >> + fprintf(stderr, >> + "Environment variables containing paths and ports " >> + "each separated by a colon:\n"); >> fprintf(stderr, >> "* %s: list of paths allowed to be used in a read-only way.\n", >> ENV_FS_RO_NAME); >> fprintf(stderr, >> - "* %s: list of paths allowed to be used in a read-write way.\n", >> + "* %s: list of paths allowed to be used in a read-write way.\n\n", >> ENV_FS_RW_NAME); >> + fprintf(stderr, >> + "Environment variables containing ports are optional " >> + "and could be skipped.\n"); >> + fprintf(stderr, >> + "* %s: list of ports allowed to bind (server).\n", >> + ENV_TCP_BIND_NAME); >> + fprintf(stderr, >> + "* %s: list of ports allowed to connect (client).\n", >> + ENV_TCP_CONNECT_NAME); >> fprintf(stderr, >> "\nexample:\n" >> "%s=\"/bin:/lib:/usr:/proc:/etc:/dev/urandom\" " >> "%s=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" " >> + "%s=\"9418\" " >> + "%s=\"80:443\" " >> "%s bash -i\n", >> - ENV_FS_RO_NAME, ENV_FS_RW_NAME, argv[0]); >> + ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME, >> + ENV_TCP_CONNECT_NAME, argv[0]); >> return 1; >> } >> >> @@ -224,15 +300,32 @@ int main(const int argc, char *const argv[], char *const *const envp) >> } >> return 1; >> } >> + >> + /* Adds optionally network bind() support. */ >> + env_port_name = getenv(ENV_TCP_BIND_NAME); >> + if (env_port_name) { >> + access_net_tcp |= LANDLOCK_ACCESS_NET_BIND_TCP; >> + } >> + /* Adds optionally network connect() support. */ >> + env_port_name = getenv(ENV_TCP_CONNECT_NAME); >> + if (env_port_name) { >> + access_net_tcp |= LANDLOCK_ACCESS_NET_CONNECT_TCP; >> + } >> + ruleset_attr.handled_access_net = access_net_tcp; >> + >> /* Best-effort security. */ >> switch (abi) { >> case 1: >> /* Removes LANDLOCK_ACCESS_FS_REFER for ABI < 2 */ >> ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_REFER; >> + /* Removes network support for ABI < 2 */ >> + ruleset_attr.handled_access_net = 0; > > Same issue as for the documentation. So I need to add refactored code into documentation? > > >> __attribute__((fallthrough)); >> case 2: >> /* Removes LANDLOCK_ACCESS_FS_TRUNCATE for ABI < 3 */ >> ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_TRUNCATE; >> + /* Removes network support for ABI < 3 */ >> + ruleset_attr.handled_access_net = 0; >> } >> access_fs_ro &= ruleset_attr.handled_access_fs; >> access_fs_rw &= ruleset_attr.handled_access_fs; >> @@ -243,10 +336,18 @@ int main(const int argc, char *const argv[], char *const *const envp) >> perror("Failed to create a ruleset"); >> return 1; >> } >> - if (populate_ruleset(ENV_FS_RO_NAME, ruleset_fd, access_fs_ro)) { >> + if (populate_ruleset_fs(ENV_FS_RO_NAME, ruleset_fd, access_fs_ro)) { >> + goto err_close_ruleset; >> + } >> + if (populate_ruleset_fs(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) { >> + goto err_close_ruleset; >> + } >> + if (populate_ruleset_net(ENV_TCP_BIND_NAME, ruleset_fd, >> + LANDLOCK_ACCESS_NET_BIND_TCP)) { >> goto err_close_ruleset; >> } >> - if (populate_ruleset(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) { >> + if (populate_ruleset_net(ENV_TCP_CONNECT_NAME, ruleset_fd, >> + LANDLOCK_ACCESS_NET_CONNECT_TCP)) { >> goto err_close_ruleset; >> } >> if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) { >> -- >> 2.25.1 >> > .
Powered by blists - more mailing lists