diff options
Diffstat (limited to 'security/landlock/fs.c')
| -rw-r--r-- | security/landlock/fs.c | 114 |
1 files changed, 59 insertions, 55 deletions
diff --git a/security/landlock/fs.c b/security/landlock/fs.c index e31b97a9f175..71b9dc331aae 100644 --- a/security/landlock/fs.c +++ b/security/landlock/fs.c @@ -36,6 +36,7 @@ #include <uapi/linux/fiemap.h> #include <uapi/linux/landlock.h> +#include "access.h" #include "common.h" #include "cred.h" #include "fs.h" @@ -388,14 +389,6 @@ static bool is_nouser_or_private(const struct dentry *dentry) unlikely(IS_PRIVATE(d_backing_inode(dentry)))); } -static access_mask_t -get_handled_fs_accesses(const struct landlock_ruleset *const domain) -{ - /* Handles all initially denied by default access rights. */ - return landlock_union_access_masks(domain).fs | - LANDLOCK_ACCESS_FS_INITIALLY_DENIED; -} - static const struct access_masks any_fs = { .fs = ~0, }; @@ -572,6 +565,12 @@ static void test_no_more_access(struct kunit *const test) #undef NMA_TRUE #undef NMA_FALSE +static bool is_layer_masks_allowed( + layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]) +{ + return !memchr_inv(layer_masks, 0, sizeof(*layer_masks)); +} + /* * Removes @layer_masks accesses that are not requested. * @@ -589,7 +588,8 @@ scope_to_request(const access_mask_t access_request, for_each_clear_bit(access_bit, &access_req, ARRAY_SIZE(*layer_masks)) (*layer_masks)[access_bit] = 0; - return !memchr_inv(layer_masks, 0, sizeof(*layer_masks)); + + return is_layer_masks_allowed(layer_masks); } #ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST @@ -778,16 +778,21 @@ static bool is_access_to_paths_allowed( if (WARN_ON_ONCE(domain->num_layers < 1 || !layer_masks_parent1)) return false; + allowed_parent1 = is_layer_masks_allowed(layer_masks_parent1); + if (unlikely(layer_masks_parent2)) { if (WARN_ON_ONCE(!dentry_child1)) return false; + + allowed_parent2 = is_layer_masks_allowed(layer_masks_parent2); + /* * For a double request, first check for potential privilege * escalation by looking at domain handled accesses (which are * a superset of the meaningful requested accesses). */ access_masked_parent1 = access_masked_parent2 = - get_handled_fs_accesses(domain); + landlock_union_access_masks(domain).fs; is_dom_check = true; } else { if (WARN_ON_ONCE(dentry_child1 || dentry_child2)) @@ -847,15 +852,6 @@ static bool is_access_to_paths_allowed( child1_is_directory, layer_masks_parent2, layer_masks_child2, child2_is_directory))) { - allowed_parent1 = scope_to_request( - access_request_parent1, layer_masks_parent1); - allowed_parent2 = scope_to_request( - access_request_parent2, layer_masks_parent2); - - /* Stops when all accesses are granted. */ - if (allowed_parent1 && allowed_parent2) - break; - /* * Now, downgrades the remaining checks from domain * handled accesses to requested accesses. @@ -863,15 +859,32 @@ static bool is_access_to_paths_allowed( is_dom_check = false; access_masked_parent1 = access_request_parent1; access_masked_parent2 = access_request_parent2; + + allowed_parent1 = + allowed_parent1 || + scope_to_request(access_masked_parent1, + layer_masks_parent1); + allowed_parent2 = + allowed_parent2 || + scope_to_request(access_masked_parent2, + layer_masks_parent2); + + /* Stops when all accesses are granted. */ + if (allowed_parent1 && allowed_parent2) + break; } rule = find_rule(domain, walker_path.dentry); - allowed_parent1 = landlock_unmask_layers( - rule, access_masked_parent1, layer_masks_parent1, - ARRAY_SIZE(*layer_masks_parent1)); - allowed_parent2 = landlock_unmask_layers( - rule, access_masked_parent2, layer_masks_parent2, - ARRAY_SIZE(*layer_masks_parent2)); + allowed_parent1 = allowed_parent1 || + landlock_unmask_layers( + rule, access_masked_parent1, + layer_masks_parent1, + ARRAY_SIZE(*layer_masks_parent1)); + allowed_parent2 = allowed_parent2 || + landlock_unmask_layers( + rule, access_masked_parent2, + layer_masks_parent2, + ARRAY_SIZE(*layer_masks_parent2)); /* Stops when a rule from each layer grants access. */ if (allowed_parent1 && allowed_parent2) @@ -895,8 +908,10 @@ jump_up: * access to internal filesystems (e.g. nsfs, which is * reachable through /proc/<pid>/ns/<namespace>). */ - allowed_parent1 = allowed_parent2 = - !!(walker_path.mnt->mnt_flags & MNT_INTERNAL); + if (walker_path.mnt->mnt_flags & MNT_INTERNAL) { + allowed_parent1 = true; + allowed_parent2 = true; + } break; } parent_dentry = dget_parent(walker_path.dentry); @@ -908,39 +923,29 @@ jump_up: return allowed_parent1 && allowed_parent2; } -static int check_access_path(const struct landlock_ruleset *const domain, - const struct path *const path, - access_mask_t access_request) -{ - layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {}; - - access_request = landlock_init_layer_masks( - domain, access_request, &layer_masks, LANDLOCK_KEY_INODE); - if (is_access_to_paths_allowed(domain, path, access_request, - &layer_masks, NULL, 0, NULL, NULL)) - return 0; - return -EACCES; -} - static int current_check_access_path(const struct path *const path, - const access_mask_t access_request) + access_mask_t access_request) { const struct landlock_ruleset *const dom = get_current_fs_domain(); + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {}; if (!dom) return 0; - return check_access_path(dom, path, access_request); + + access_request = landlock_init_layer_masks( + dom, access_request, &layer_masks, LANDLOCK_KEY_INODE); + if (is_access_to_paths_allowed(dom, path, access_request, &layer_masks, + NULL, 0, NULL, NULL)) + return 0; + + return -EACCES; } -static access_mask_t get_mode_access(const umode_t mode) +static __attribute_const__ access_mask_t get_mode_access(const umode_t mode) { switch (mode & S_IFMT) { case S_IFLNK: return LANDLOCK_ACCESS_FS_MAKE_SYM; - case 0: - /* A zero mode translates to S_IFREG. */ - case S_IFREG: - return LANDLOCK_ACCESS_FS_MAKE_REG; case S_IFDIR: return LANDLOCK_ACCESS_FS_MAKE_DIR; case S_IFCHR: @@ -951,9 +956,12 @@ static access_mask_t get_mode_access(const umode_t mode) return LANDLOCK_ACCESS_FS_MAKE_FIFO; case S_IFSOCK: return LANDLOCK_ACCESS_FS_MAKE_SOCK; + case S_IFREG: + case 0: + /* A zero mode translates to S_IFREG. */ default: - WARN_ON_ONCE(1); - return 0; + /* Treats weird files as regular files. */ + return LANDLOCK_ACCESS_FS_MAKE_REG; } } @@ -1414,11 +1422,7 @@ static int hook_path_mknod(const struct path *const dir, struct dentry *const dentry, const umode_t mode, const unsigned int dev) { - const struct landlock_ruleset *const dom = get_current_fs_domain(); - - if (!dom) - return 0; - return check_access_path(dom, dir, get_mode_access(mode)); + return current_check_access_path(dir, get_mode_access(mode)); } static int hook_path_symlink(const struct path *const dir, |