| Message ID | 20230323085226.1432550-13-konstantin.meskhidze@huawei.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | Network support for Landlock | expand |
On 23/03/2023 09:52, 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@huawei.com> > --- > > Changes since v9: > * Deletes ports converting. > * Minor fixes. > > Changes since v8: > * Convert ports to __be16. > * Minor fixes. > > Changes since v7: > * Removes network support if ABI < 4. > * Removes network support if not set by a user. > > 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 | 130 +++++++++++++++++++++++++++++++---- > 1 file changed, 118 insertions(+), 12 deletions(-) > > diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c > index e2056c8b902c..b8f00e4dba95 100644 > --- a/samples/landlock/sandboxer.c > +++ b/samples/landlock/sandboxer.c > @@ -8,6 +8,7 @@ > */ > > #define _GNU_SOURCE > +#include <arpa/inet.h> > #include <errno.h> > #include <fcntl.h> > #include <linux/landlock.h> > @@ -51,6 +52,8 @@ 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 +74,20 @@ 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 +98,8 @@ 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 +160,47 @@ 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, .allowed_access = allowed_access, > + .port = 0, > + }; > + > + env_port_name = getenv(env_var); > + if (!env_port_name) { > + return 0; > + } > + 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; This previous line can now be removed. > + 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 \"%lld\": %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 ( \ > @@ -166,39 +224,58 @@ static int populate_ruleset(const char *const env_var, const int ruleset_fd, > > /* clang-format on */ > > -#define LANDLOCK_ABI_LAST 3 > +#define LANDLOCK_ABI_LAST 4 > > 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; > + > struct landlock_ruleset_attr ruleset_attr = { > .handled_access_fs = access_fs_rw, > + .handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP | > + LANDLOCK_ACCESS_NET_CONNECT_TCP, > }; > > 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\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]); > fprintf(stderr, > "This sandboxer can use Landlock features " > "up to ABI version %d.\n", > @@ -255,7 +332,12 @@ int main(const int argc, char *const argv[], char *const *const envp) > case 2: > /* Removes LANDLOCK_ACCESS_FS_TRUNCATE for ABI < 3 */ > ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_TRUNCATE; > - > + __attribute__((fallthrough)); > + case 3: > + /* Removes network support for ABI < 4 */ > + ruleset_attr.handled_access_net &= > + ~(LANDLOCK_ACCESS_NET_BIND_TCP | > + LANDLOCK_ACCESS_NET_CONNECT_TCP); > fprintf(stderr, > "Hint: You should update the running kernel " > "to leverage Landlock features " > @@ -274,18 +356,42 @@ int main(const int argc, char *const argv[], char *const *const envp) > access_fs_ro &= ruleset_attr.handled_access_fs; > access_fs_rw &= ruleset_attr.handled_access_fs; > > + /* Removes bind access attribute if not supported by a user. */ > + env_port_name = getenv(ENV_TCP_BIND_NAME); > + if (!env_port_name) { > + ruleset_attr.handled_access_net &= > + ~LANDLOCK_ACCESS_NET_BIND_TCP; > + } > + /* Removes connect access attribute if not supported by a user. */ > + env_port_name = getenv(ENV_TCP_CONNECT_NAME); > + if (!env_port_name) { > + ruleset_attr.handled_access_net &= > + ~LANDLOCK_ACCESS_NET_CONNECT_TCP; > + } > + > ruleset_fd = > landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0); > if (ruleset_fd < 0) { > 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(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) { > + > + if (populate_ruleset_net(ENV_TCP_BIND_NAME, ruleset_fd, > + LANDLOCK_ACCESS_NET_BIND_TCP)) { > goto err_close_ruleset; > } > + 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)) { > perror("Failed to restrict privileges"); > goto err_close_ruleset; > -- > 2.25.1 >
4/16/2023 7:13 PM, Mickaël Salaün пишет: > > On 23/03/2023 09:52, 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@huawei.com> >> --- >> >> Changes since v9: >> * Deletes ports converting. >> * Minor fixes. >> >> Changes since v8: >> * Convert ports to __be16. >> * Minor fixes. >> >> Changes since v7: >> * Removes network support if ABI < 4. >> * Removes network support if not set by a user. >> >> 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 | 130 +++++++++++++++++++++++++++++++---- >> 1 file changed, 118 insertions(+), 12 deletions(-) >> >> diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c >> index e2056c8b902c..b8f00e4dba95 100644 >> --- a/samples/landlock/sandboxer.c >> +++ b/samples/landlock/sandboxer.c >> @@ -8,6 +8,7 @@ >> */ >> >> #define _GNU_SOURCE >> +#include <arpa/inet.h> >> #include <errno.h> >> #include <fcntl.h> >> #include <linux/landlock.h> >> @@ -51,6 +52,8 @@ 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 +74,20 @@ 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 +98,8 @@ 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 +160,47 @@ 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, > > .allowed_access = allowed_access, Got it. > >> + .port = 0, >> + }; >> + >> + env_port_name = getenv(env_var); >> + if (!env_port_name) { >> + return 0; >> + } >> + 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; > > This previous line can now be removed. Ok. Thanks for the tip. > > >> + 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 \"%lld\": %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 ( \ >> @@ -166,39 +224,58 @@ static int populate_ruleset(const char *const env_var, const int ruleset_fd, >> >> /* clang-format on */ >> >> -#define LANDLOCK_ABI_LAST 3 >> +#define LANDLOCK_ABI_LAST 4 >> >> 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; >> + >> struct landlock_ruleset_attr ruleset_attr = { >> .handled_access_fs = access_fs_rw, >> + .handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP | >> + LANDLOCK_ACCESS_NET_CONNECT_TCP, >> }; >> >> 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\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]); >> fprintf(stderr, >> "This sandboxer can use Landlock features " >> "up to ABI version %d.\n", >> @@ -255,7 +332,12 @@ int main(const int argc, char *const argv[], char *const *const envp) >> case 2: >> /* Removes LANDLOCK_ACCESS_FS_TRUNCATE for ABI < 3 */ >> ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_TRUNCATE; >> - >> + __attribute__((fallthrough)); >> + case 3: >> + /* Removes network support for ABI < 4 */ >> + ruleset_attr.handled_access_net &= >> + ~(LANDLOCK_ACCESS_NET_BIND_TCP | >> + LANDLOCK_ACCESS_NET_CONNECT_TCP); >> fprintf(stderr, >> "Hint: You should update the running kernel " >> "to leverage Landlock features " >> @@ -274,18 +356,42 @@ int main(const int argc, char *const argv[], char *const *const envp) >> access_fs_ro &= ruleset_attr.handled_access_fs; >> access_fs_rw &= ruleset_attr.handled_access_fs; >> >> + /* Removes bind access attribute if not supported by a user. */ >> + env_port_name = getenv(ENV_TCP_BIND_NAME); >> + if (!env_port_name) { >> + ruleset_attr.handled_access_net &= >> + ~LANDLOCK_ACCESS_NET_BIND_TCP; >> + } >> + /* Removes connect access attribute if not supported by a user. */ >> + env_port_name = getenv(ENV_TCP_CONNECT_NAME); >> + if (!env_port_name) { >> + ruleset_attr.handled_access_net &= >> + ~LANDLOCK_ACCESS_NET_CONNECT_TCP; >> + } >> + >> ruleset_fd = >> landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0); >> if (ruleset_fd < 0) { >> 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(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) { >> + >> + if (populate_ruleset_net(ENV_TCP_BIND_NAME, ruleset_fd, >> + LANDLOCK_ACCESS_NET_BIND_TCP)) { >> goto err_close_ruleset; >> } >> + 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)) { >> perror("Failed to restrict privileges"); >> goto err_close_ruleset; >> -- >> 2.25.1 >> > .
diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c index e2056c8b902c..b8f00e4dba95 100644 --- a/samples/landlock/sandboxer.c +++ b/samples/landlock/sandboxer.c @@ -8,6 +8,7 @@ */ #define _GNU_SOURCE +#include <arpa/inet.h> #include <errno.h> #include <fcntl.h> #include <linux/landlock.h> @@ -51,6 +52,8 @@ 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 +74,20 @@ 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 +98,8 @@ 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 +160,47 @@ 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) { + return 0; + } + 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 \"%lld\": %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 ( \ @@ -166,39 +224,58 @@ static int populate_ruleset(const char *const env_var, const int ruleset_fd, /* clang-format on */ -#define LANDLOCK_ABI_LAST 3 +#define LANDLOCK_ABI_LAST 4 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; + struct landlock_ruleset_attr ruleset_attr = { .handled_access_fs = access_fs_rw, + .handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP | + LANDLOCK_ACCESS_NET_CONNECT_TCP, }; 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\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]); fprintf(stderr, "This sandboxer can use Landlock features " "up to ABI version %d.\n", @@ -255,7 +332,12 @@ int main(const int argc, char *const argv[], char *const *const envp) case 2: /* Removes LANDLOCK_ACCESS_FS_TRUNCATE for ABI < 3 */ ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_TRUNCATE; - + __attribute__((fallthrough)); + case 3: + /* Removes network support for ABI < 4 */ + ruleset_attr.handled_access_net &= + ~(LANDLOCK_ACCESS_NET_BIND_TCP | + LANDLOCK_ACCESS_NET_CONNECT_TCP); fprintf(stderr, "Hint: You should update the running kernel " "to leverage Landlock features " @@ -274,18 +356,42 @@ int main(const int argc, char *const argv[], char *const *const envp) access_fs_ro &= ruleset_attr.handled_access_fs; access_fs_rw &= ruleset_attr.handled_access_fs; + /* Removes bind access attribute if not supported by a user. */ + env_port_name = getenv(ENV_TCP_BIND_NAME); + if (!env_port_name) { + ruleset_attr.handled_access_net &= + ~LANDLOCK_ACCESS_NET_BIND_TCP; + } + /* Removes connect access attribute if not supported by a user. */ + env_port_name = getenv(ENV_TCP_CONNECT_NAME); + if (!env_port_name) { + ruleset_attr.handled_access_net &= + ~LANDLOCK_ACCESS_NET_CONNECT_TCP; + } + ruleset_fd = landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0); if (ruleset_fd < 0) { 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(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) { + + if (populate_ruleset_net(ENV_TCP_BIND_NAME, ruleset_fd, + LANDLOCK_ACCESS_NET_BIND_TCP)) { goto err_close_ruleset; } + 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)) { perror("Failed to restrict privileges"); goto err_close_ruleset;
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@huawei.com> --- Changes since v9: * Deletes ports converting. * Minor fixes. Changes since v8: * Convert ports to __be16. * Minor fixes. Changes since v7: * Removes network support if ABI < 4. * Removes network support if not set by a user. 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 | 130 +++++++++++++++++++++++++++++++---- 1 file changed, 118 insertions(+), 12 deletions(-) -- 2.25.1